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Sample records for virulence factor biogenesis

  1. Δ(1-pyrroline-5-carboxylate/glutamate biogenesis is required for fungal virulence and sporulation.

    Directory of Open Access Journals (Sweden)

    Ziting Yao

    Full Text Available Proline dehydrogenase (Prodh and Δ(1-pyrroline-5-carboxylate dehydrogenase (P5Cdh are two key enzymes in the cellular biogenesis of glutamate. Recombinant Prodh and P5Cdh proteins of the chestnut blight fungus Cryphonectria parasitica were investigated and showed activity in in vitro assays. Additionally, the C. parasitica Prodh and P5Cdh genes were able to complement the Saccharomyces cerevisiae put1 and put2 null mutants, respectively, to allow these proline auxotrophic yeast mutants to grow on media with proline as the sole source of nitrogen. Deletion of the Prodh gene in C. parasitica resulted in hypovirulence and a lower level of sporulation, whereas deletion of P5Cdh resulted in hypovirulence though no effect on sporulation; both Δprodh and Δp5cdh mutants were unable to grow on minimal medium with proline as the sole nitrogen source. In a wild-type strain, the intracellular level of proline and the activity of Prodh and P5Cdh increased after supplementation of exogenous proline, though the intracellular Δ(1-pyrroline-5-carboxylate (P5C content remained unchanged. Prodh and P5Cdh were both transcriptionally down-regulated in cells infected with hypovirus. The disruption of other genes with products involved in the conversion of arginine to ornithine, ornithine and glutamate to P5C, and P5C to proline in the cytosol did not appear to affect virulence; however, asexual sporulation was reduced in the Δpro1 and Δpro2 mutants. Taken together, our results showed that Prodh, P5Cdh and related mitochondrial functions are essential for virulence and that proline/glutamate pathway components may represent down-stream targets of hypovirus regulation in C. parasitica.

  2. Campylobacter virulence and survival factors.

    Science.gov (United States)

    Bolton, Declan J

    2015-06-01

    Despite over 30 years of research, campylobacteriosis is the most prevalent foodborne bacterial infection in many countries including in the European Union and the United States of America. However, relatively little is known about the virulence factors in Campylobacter or how an apparently fragile organism can survive in the food chain, often with enhanced pathogenicity. This review collates information on the virulence and survival determinants including motility, chemotaxis, adhesion, invasion, multidrug resistance, bile resistance and stress response factors. It discusses their function in transition through the food processing environment and human infection. In doing so it provides a fundamental understanding of Campylobacter, critical for improved diagnosis, surveillance and control. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. High-throughput identification of chemical inhibitors of E. coli Group 2 capsule biogenesis as anti-virulence agents.

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    Carlos C Goller

    Full Text Available Rising antibiotic resistance among Escherichia coli, the leading cause of urinary tract infections (UTIs, has placed a new focus on molecular pathogenesis studies, aiming to identify new therapeutic targets. Anti-virulence agents are attractive as chemotherapeutics to attenuate an organism during disease but not necessarily during benign commensalism, thus decreasing the stress on beneficial microbial communities and lessening the emergence of resistance. We and others have demonstrated that the K antigen capsule of E. coli is a preeminent virulence determinant during UTI and more invasive diseases. Components of assembly and export are highly conserved among the major K antigen capsular types associated with UTI-causing E. coli and are distinct from the capsule biogenesis machinery of many commensal E. coli, making these attractive therapeutic targets. We conducted a screen for anti-capsular small molecules and identified an agent designated "C7" that blocks the production of K1 and K5 capsules, unrelated polysaccharide types among the Group 2-3 capsules. Herein lies proof-of-concept that this screen may be implemented with larger chemical libraries to identify second-generation small-molecule inhibitors of capsule biogenesis. These inhibitors will lead to a better understanding of capsule biogenesis and may represent a new class of therapeutics.

  4. Structural Genomics of Bacterial Virulence Factors

    National Research Council Canada - National Science Library

    Liddington, Robert

    2004-01-01

    We are applying a comprehensive yet focused structural genomics approach to determine the atomic resolution crystal structures of key bacterial virulence factors from high priority bacterial pathogens...

  5. Virulence Factors of A Review

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    Bruna M. Roesler

    2014-07-01

    Full Text Available Helicobacter pylori is a spiral-shaped Gram-negative bacterium that colonizes the human stomach and can establish a long-term infection of the gastric mucosa, a condition that affects the relative risk of developing various clinical disorders of the upper gastrointestinal tract, such as chronic gastritis, peptic ulcer disease, mucosa-associated lymphoid tissue (MALT lymphoma, and gastric adenocarcinoma. H. pylori presents a high-level of genetic diversity, which can be an important factor in its adaptation to the host stomach and also for the clinical outcome of infection. There are important H. pylori virulence factors that, along with host characteristics and the external environment, have been associated with the different occurrences of diseases. This review is aimed to analyzing and summarizing the main of them and possible associations with the clinical outcome.

  6. The Rhodococcus equi virulence protein VapA disrupts endolysosome function and stimulates lysosome biogenesis

    OpenAIRE

    Rofe, Adam P; Davis, Luther J.; Whittingham, Jean L.; Latimer-Bowman, Elizabeth C; Wilkinson, Anthony J.; Pryor, Paul Robert

    2016-01-01

    Abstract Rhodococcus equi (R.?equi) is an important pulmonary pathogen in foals that often leads to the death of the horse. The bacterium harbors a virulence plasmid that encodes numerous virulence?associated proteins (Vaps) including VapA that is essential for intracellular survival inside macrophages. However, little is known about the precise function of VapA. Here, we demonstrate that VapA causes perturbation to late endocytic organelles with swollen endolysosome organelles having reduced...

  7. Virulence Factors IN Fungi OF Systemic Mycoses

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    KUROKAWA Cilmery Suemi

    1998-01-01

    Full Text Available Pathogenic fungi that cause systemic mycoses retain several factors which allow their growth in adverse conditions provided by the host, leading to the establishment of the parasitic relationship and contributing to disease development. These factors are known as virulence factors which favor the infection process and the pathogenesis of the mycoses. The present study evaluates the virulence factors of pathogenic fungi such as Blastomyces dermatitidis, Coccidioides immitis, Cryptococcus neoformans, Histoplasma capsulatum and Paracoccidioides brasiliensis in terms of thermotolerance, dimorphism, capsule or cell wall components as well as enzyme production. Virulence factors favor fungal adhesion, colonization, dissemination and the ability to survive in hostile environments and elude the immune response mechanisms of the host. Both the virulence factors presented by different fungi and the defense mechanisms provided by the host require action and interaction of complex processes whose knowledge allows a better understanding of the pathogenesis of systemic mycoses.

  8. Placeholder factors in ribosome biogenesis: please, pave my way

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    Francisco J. Espinar-Marchena

    2017-04-01

    Full Text Available The synthesis of cytoplasmic eukaryotic ribosomes is an extraordinarily energy-demanding cellular activity that occurs progressively from the nucleolus to the cytoplasm. In the nucleolus, precursor rRNAs associate with a myriad of trans-acting factors and some ribosomal proteins to form pre-ribosomal particles. These factors include snoRNPs, nucleases, ATPases, GTPases, RNA helicases, and a vast list of proteins with no predicted enzymatic activity. Their coordinate activity orchestrates in a spatiotemporal manner the modification and processing of precursor rRNAs, the rearrangement reactions required for the formation of productive RNA folding intermediates, the ordered assembly of the ribosomal proteins, and the export of pre-ribosomal particles to the cytoplasm; thus, providing speed, directionality and accuracy to the overall process of formation of translation-competent ribosomes. Here, we review a particular class of trans-acting factors known as “placeholders”. Placeholder factors temporarily bind selected ribosomal sites until these have achieved a structural context that is appropriate for exchanging the placeholder with another site-specific binding factor. By this strategy, placeholders sterically prevent premature recruitment of subsequently binding factors, premature formation of structures, avoid possible folding traps, and act as molecular clocks that supervise the correct progression of pre-ribosomal particles into functional ribosomal subunits. We summarize the current understanding of those factors that delay the assembly of distinct ribosomal proteins or subsequently bind key sites in pre-ribosomal particles. We also discuss recurrent examples of RNA-protein and protein-protein mimicry between rRNAs and/or factors, which have clear functional implications for the ribosome biogenesis pathway.

  9. A Glycosylphosphatidylinositol-Anchored Carbonic Anhydrase-Related Protein of Toxoplasma gondii Is Important for Rhoptry Biogenesis and Virulence.

    Science.gov (United States)

    Chasen, Nathan M; Asady, Beejan; Lemgruber, Leandro; Vommaro, Rossiane C; Kissinger, Jessica C; Coppens, Isabelle; Moreno, Silvia N J

    2017-01-01

    Carbonic anhydrase-related proteins (CARPs) have previously been described as catalytically inactive proteins closely related to α-carbonic anhydrases (α-CAs). These CARPs are found in animals (both vertebrates and invertebrates) and viruses as either independent proteins or domains of other proteins. We report here the identification of a new CARP (TgCA_RP) in the unicellular organism Toxoplasma gondii that is related to the recently described η-class CA found in Plasmodium falciparum. TgCA_RP is posttranslationally modified at its C terminus with a glycosylphosphatidylinositol anchor that is important for its localization in intracellular tachyzoites. The protein localizes throughout the rhoptry bulbs of mature tachyzoites and to the outer membrane of nascent rhoptries in dividing tachyzoites, as demonstrated by immunofluorescence and immunoelectron microscopy using specific antibodies. T. gondii mutant tachyzoites lacking TgCA_RP display a growth and invasion phenotype in vitro and have atypical rhoptry morphology. The mutants also exhibit reduced virulence in a mouse model. Our results show that TgCA_RP plays an important role in the biogenesis of rhoptries. IMPORTANCEToxoplasma gondii is an intracellular pathogen that infects humans and animals. The pathogenesis of T. gondii is linked to its lytic cycle, which starts when tachyzoites invade host cells and secrete proteins from specialized organelles. Once inside the host cell, the parasite creates a parasitophorous vacuole (PV) where it divides. Rhoptries are specialized secretory organelles that contain proteins, many of which are secreted during invasion. These proteins have important roles not only during the initial interaction between parasite and host but also in the formation of the PV and in the modification of the host cell. We report here the identification of a new T. gondii carbonic anhydrase-related protein (TgCA_RP), which localizes to rhoptries of mature tachyzoites. TgCA_RP is important

  10. Crucial roles of abscisic acid biogenesis in virulence of rice blast fungus Magnaporthe oryzae

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    Carla eSpence

    2015-12-01

    Full Text Available Rice suffers dramatic yield losses due to blast pathogen Magnaporthe oryzae. Pseudomonas chlororaphis EA105, a bacterium that was isolated from the rice rhizosphere, inhibits M. oryzae. It was shown previously that pre-treatment of rice with EA105 reduced the size of blast lesions through JA- and ETH-mediated ISR. ABA acts antagonistically towards SA, JA, and ETH signaling, to impede plant defense responses. EA105 may be reducing the virulence of M. oryzae by preventing the pathogen from up-regulating the key ABA biosynthetic gene NCED3 in rice roots, as well as a β-glucosidase likely involved in activating conjugated inactive forms of ABA. However, changes in total ABA concentrations were not apparent, provoking the question of whether ABA concentration is an indicator of ABA signaling and response. In the rice-M. oryzae interaction, ABA plays a dual role in disease severity by increasing plant susceptibility and accelerating pathogenesis in the fungus itself. ABA is biosynthesized by M. oryzae. Further, exogenous ABA increased spore germination and appressoria formation, distinct from other plant growth regulators. EA105, which inhibits appressoria formation, counteracted the virulence-promoting effects of ABA on M. oryzae. The role of endogenous fungal ABA in blast disease was confirmed through the inability of a knockout mutant impaired in ABA biosynthesis to form lesions on rice. Therefore, it appears that EA105 is invoking multiple strategies in its protection of rice from blast including direct mechanisms as well as those mediated through plant signaling. ABA is a molecule that is likely implicated in both tactics.

  11. Virulence factors of the Mycobacterium tuberculosis complex

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    Forrellad, Marina A.; Klepp, Laura I.; Gioffré, Andrea; Sabio y García, Julia; Morbidoni, Hector R.; Santangelo, María de la Paz; Cataldi, Angel A.; Bigi, Fabiana

    2013-01-01

    The Mycobacterium tuberculosis complex (MTBC) consists of closely related species that cause tuberculosis in both humans and animals. This illness, still today, remains to be one of the leading causes of morbidity and mortality throughout the world. The mycobacteria enter the host by air, and, once in the lungs, are phagocytated by macrophages. This may lead to the rapid elimination of the bacillus or to the triggering of an active tuberculosis infection. A large number of different virulence factors have evolved in MTBC members as a response to the host immune reaction. The aim of this review is to describe the bacterial genes/proteins that are essential for the virulence of MTBC species, and that have been demonstrated in an in vivo model of infection. Knowledge of MTBC virulence factors is essential for the development of new vaccines and drugs to help manage the disease toward an increasingly more tuberculosis-free world. PMID:23076359

  12. Helicobacter pylori virulence factors in gastric carcinogenesis

    OpenAIRE

    Wen, Sicheng; Moss, Steven F.

    2008-01-01

    Helicobacter pylori infection is the most important risk factor in the development of non-cardia gastric adenocarcinoma; host genetic variability and dietary co-factors also modulate risk. Because most H. pylori infections do not cause cancer, H. pylori heterogeneity has been investigated to identify possible virulence factors. The strongest candidates are genes within the cag (cytotoxin associated antigen) pathogenicity island, including the gene encoding the CagA protein, as well as polymor...

  13. The Splicing Factor Prp43p, a DEAH Box ATPase, Functions in Ribosome Biogenesis

    Science.gov (United States)

    Leeds, Nina B.; Small, Eliza C.; Hiley, Shawna L.; Hughes, Timothy R.; Staley, Jonathan P.

    2006-01-01

    Biogenesis of the small and large ribosomal subunits requires modification, processing, and folding of pre-rRNA to yield mature rRNA. Here, we report that efficient biogenesis of both small- and large-subunit rRNAs requires the DEAH box ATPase Prp43p, a pre-mRNA splicing factor. By steady-state analysis, a cold-sensitive prp43 mutant accumulates 35S pre-rRNA and depletes 20S, 27S, and 7S pre-rRNAs, precursors to the small- and large-subunit rRNAs. By pulse-chase analysis, the prp43 mutant is defective in the formation of 20S and 27S pre-rRNAs and in the accumulation of 18S and 25S mature rRNAs. Wild-type Prp43p immunoprecipitates pre-rRNAs and mature rRNAs, indicating a direct role in ribosome biogenesis. The Prp43p-Q423N mutant immunoprecipitates 27SA2 pre-rRNA threefold more efficiently than the wild type, suggesting a critical role for Prp43p at the earliest stages of large-subunit biogenesis. Consistent with an early role for Prp43p in ribosome biogenesis, Prp43p immunoprecipitates the majority of snoRNAs; further, compared to the wild type, the prp43 mutant generally immunoprecipitates the snoRNAs more efficiently. In the prp43 mutant, the snoRNA snR64 fails to methylate residue C2337 in 27S pre-rRNA, suggesting a role in snoRNA function. We propose that Prp43p promotes recycling of snoRNAs and biogenesis factors during pre-rRNA processing, similar to its recycling role in pre-mRNA splicing. The dual function for Prp43p in the cell raises the possibility that ribosome biogenesis and pre-mRNA splicing may be coordinately regulated. PMID:16382143

  14. Brucella spp. Virulence Factors and Immunity.

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    Byndloss, Mariana X; Tsolis, Renee M

    2016-01-01

    Brucellosis, caused by bacteria of the genus Brucella, is an important zoonotic infection that causes reproductive disease in domestic animals and chronic debilitating disease in humans. An intriguing aspect of Brucella infection is the ability of these bacteria to evade the host immune response, leading to pathogen persistence. Conversely, in the reproductive tract of infected animals, this stealthy pathogen is able to cause an acute severe inflammatory response. In this review, we discuss the different mechanisms used by Brucella to cause disease, with emphasis on its virulence factors and the dichotomy between chronic persistence and reproductive disease.

  15. Expression of virulence factors by Staphylococcus aureus grown in serum.

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    Oogai, Yuichi; Matsuo, Miki; Hashimoto, Masahito; Kato, Fuminori; Sugai, Motoyuki; Komatsuzawa, Hitoshi

    2011-11-01

    Staphylococcus aureus produces many virulence factors, including toxins, immune-modulatory factors, and exoenzymes. Previous studies involving the analysis of virulence expression were mainly performed by in vitro experiments using bacterial medium. However, when S. aureus infects a host, the bacterial growth conditions are quite different from those in a medium, which may be related to the different expression of virulence factors in the host. In this study, we investigated the expression of virulence factors in S. aureus grown in calf serum. The expression of many virulence factors, including hemolysins, enterotoxins, proteases, and iron acquisition factors, was significantly increased compared with that in bacterial medium. In addition, the expression of RNA III, a global regulon for virulence expression, was significantly increased. This effect was partially restored by the addition of 300 μM FeCl₃ into serum, suggesting that iron depletion is associated with the increased expression of virulence factors in serum. In chemically defined medium without iron, a similar effect was observed. In a mutant with agr inactivated grown in serum, the expression of RNA III, psm, and sec4 was not increased, while other factors were still induced in the mutant, suggesting that another regulatory factor(s) is involved. In addition, we found that serum albumin is a major factor for the capture of free iron to prevent the supply of iron to bacteria grown in serum. These results indicate that S. aureus expresses virulence factors in adaptation to the host environment.

  16. The Klebsiella pneumoniae YfgL (BamB) lipoprotein contributes to outer membrane protein biogenesis, type-1 fimbriae expression, anti-phagocytosis, and in vivo virulence.

    Science.gov (United States)

    Hsieh, Pei-Fang; Hsu, Chun-Ru; Chen, Chun-Tang; Lin, Tzu-Lung; Wang, Jin-Town

    2016-07-03

    Klebsiella pneumoniae is an opportunistic pathogen that causes several kinds of infections, including pneumonia, bacteremia, urinary tract infection and community-acquired pyogenic liver abscess (PLA). Adhesion is the critical first step in the infection process. Our previous work demonstrated that the transcellular translocation is exploited by K. pneumoniae strains to migrate from the gut flora into other tissues, resulting in systemic infections. However, the initial stages of K. pneumoniae infection remain unclear. In this study, we demonstrated that a K. pneumoniae strain deleted for yfgL (bamB) exhibited reduced adherence to and invasion of host cells; changed biogenesis of major β-barrel outer membrane proteins; decreased transcriptional expression of type-1 fimbriae; and increased susceptibility to vancomycin and erythromycin. The yfgL deletion mutant also had reduced ability to against neutrophil phagocytosis; exhibited decreased induction of host IL-6 production; and was profoundly attenuated for virulence in a K. pneumoniae model of bacteremia. Thus, the K. pneumoniae YfgL lipoprotein mediates in outer membrane proteins biogenesis and is crucial for anti-phagocytosis and survival in vivo. These data provide a new insight for K. pneumoniae attachment and such knowledge could facilitate preventive therapies or alternative therapies against K. pneumoniae.

  17. Detection of some virulence factors in Staphylococcus aureus ...

    African Journals Online (AJOL)

    USER

    2010-06-21

    Jun 21, 2010 ... present study was to detect some of the virulence factors in the S. aureus isolated from 360 mastitis milk samples in ... Key words: Bovine mastitis, Staphylococcus aureus, virulence factors, polymerase chain reaction (PCR), Iran. INTRODUCTION ..... staphylococcal hemolysins. Zentralbl Bakteriol Orig A.

  18. Analysis of ribosome biogenesis factor-modules in yeast cells depleted from pre-ribosomes.

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    Merl, Juliane; Jakob, Steffen; Ridinger, Katrin; Hierlmeier, Thomas; Deutzmann, Rainer; Milkereit, Philipp; Tschochner, Herbert

    2010-05-01

    Formation of eukaryotic ribosomes requires more than 150 biogenesis factors which transiently interact with the nascent ribosomal subunits. Previously, many pre-ribosomal intermediates could be distinguished by their protein composition and rRNA precursor (pre-rRNA) content. We purified complexes of ribosome biogenesis factors from yeast cells in which de novo synthesis of rRNA precursors was down-regulated by genetic means. We compared the protein composition of these largely pre-rRNA free assemblies with the one of analogous pre-ribosomal preparations by semi-quantitative mass spectrometry. The experimental setup minimizes the possibility that the analysed pre-rRNA free protein modules were derived from (partially) disrupted pre-ribosomal particles and provides thereby strong evidence for their pre-ribosome independent existence. In support of the validity of this approach (i) the predicted composition of the analysed protein modules was in agreement with previously described rRNA-free complexes and (ii) in most of the cases we could identify new candidate members of reported protein modules. An unexpected outcome of these analyses was that free large ribosomal subunits are associated with a specific set of ribosome biogenesis factors in cells where neo-production of nascent ribosomes was blocked. The data presented strengthen the idea that assembly of eukaryotic pre-ribosomal particles can result from transient association of distinct building blocks.

  19. Structural Genomics of Bacterial Virulence Factors

    Science.gov (United States)

    2006-05-01

    plant proteins. Its presence in the virulence-related pXO1 plasmid of Bacillus anthracis (pX01-01) as well as in several other pathogens makes it a...from several other bacilli; Enterococcus, Listeria , Lactococcus, Lactobacillus, or other Bacillus species. Function of proteins from this family is...virulence plasmids. Infect Immun 71: 2736-2743. Braun, L. and P. Cossart. 2000. Interactions between Listeria monocytogenes and host mammalian cells

  20. NEW VIRULENCE FACTORS OF STREPTOCOCCUS PNEUMONIAE

    NARCIS (Netherlands)

    Hermans, Peter Wilhelmus Maria; Bootsma, Jeanette Hester; Burghout, Pieter Jan; Kuipers, Oscar; Bijlsma, Johanna Jacoba Elisabeth; Kloosterman, Tomas Gerrit; Andersen, Christian O.

    2011-01-01

    The present invention provides proteins/genes, which are essential for survival, and consequently, for virulence of Streptococcus pneumoniae in vivo, and thus are ideal vaccine candidates for a vaccine preparation against pneumococcal infection. Further, also antibodies against said protein(s) are

  1. Expression Profiling of Ribosome Biogenesis Factors Reveals Nucleolin as a Novel Potential Marker to Predict Outcome in AML Patients.

    Science.gov (United States)

    Marcel, Virginie; Catez, Frédéric; Berger, Caroline M; Perrial, Emeline; Plesa, Adriana; Thomas, Xavier; Mattei, Eve; Hayette, Sandrine; Saintigny, Pierre; Bouvet, Philippe; Diaz, Jean-Jacques; Dumontet, Charles

    2017-01-01

    Acute myeloid leukemia (AML) is a heterogeneous disease. Prognosis is mainly influenced by patient age at diagnosis and cytogenetic alterations, two of the main factors currently used in AML patient risk stratification. However, additional criteria are required to improve the current risk classification and better adapt patient care. In neoplastic cells, ribosome biogenesis is increased to sustain the high proliferation rate and ribosome composition is altered to modulate specific gene expression driving tumorigenesis. Here, we investigated the usage of ribosome biogenesis factors as clinical markers in adult patients with AML. We showed that nucleoli, the nucleus compartments where ribosome production takes place, are modified in AML by analyzing a panel of AML and healthy donor cells using immunofluorescence staining. Using four AML series, including the TCGA dataset, altogether representing a total of about 270 samples, we showed that not all factors involved in ribosome biogenesis have clinical values although ribosome biogenesis is increased in AML. Interestingly, we identified the regulator of ribosome production nucleolin (NCL) as over-expressed in AML blasts. Moreover, we found in two series that high NCL mRNA expression level was associated with a poor overall survival, particular in elderly patients. Multivariate analyses taking into account age and cytogenetic risk indicated that NCL expression in blast cells is an independent marker of reduced survival. Our study identifies NCL as a potential novel prognostic factor in AML. Altogether, our results suggest that the ribosome biogenesis pathway may be of interest as clinical markers in AML.

  2. Expression Profiling of Ribosome Biogenesis Factors Reveals Nucleolin as a Novel Potential Marker to Predict Outcome in AML Patients.

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    Virginie Marcel

    Full Text Available Acute myeloid leukemia (AML is a heterogeneous disease. Prognosis is mainly influenced by patient age at diagnosis and cytogenetic alterations, two of the main factors currently used in AML patient risk stratification. However, additional criteria are required to improve the current risk classification and better adapt patient care. In neoplastic cells, ribosome biogenesis is increased to sustain the high proliferation rate and ribosome composition is altered to modulate specific gene expression driving tumorigenesis. Here, we investigated the usage of ribosome biogenesis factors as clinical markers in adult patients with AML. We showed that nucleoli, the nucleus compartments where ribosome production takes place, are modified in AML by analyzing a panel of AML and healthy donor cells using immunofluorescence staining. Using four AML series, including the TCGA dataset, altogether representing a total of about 270 samples, we showed that not all factors involved in ribosome biogenesis have clinical values although ribosome biogenesis is increased in AML. Interestingly, we identified the regulator of ribosome production nucleolin (NCL as over-expressed in AML blasts. Moreover, we found in two series that high NCL mRNA expression level was associated with a poor overall survival, particular in elderly patients. Multivariate analyses taking into account age and cytogenetic risk indicated that NCL expression in blast cells is an independent marker of reduced survival. Our study identifies NCL as a potential novel prognostic factor in AML. Altogether, our results suggest that the ribosome biogenesis pathway may be of interest as clinical markers in AML.

  3. Expression and functional characterization of the Agrobacterium VirB2 amino acid substitution variants in T-pilus biogenesis, virulence, and transient transformation efficiency.

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    Hung-Yi Wu

    Full Text Available Agrobacterium tumefaciens is a phytopathogenic bacterium that causes crown gall disease by transferring transferred DNA (T-DNA into the plant genome. The translocation process is mediated by the type IV secretion system (T4SS consisting of the VirD4 coupling protein and 11 VirB proteins (VirB1 to VirB11. All VirB proteins are required for the production of T-pilus, which consists of processed VirB2 (T-pilin and VirB5 as major and minor subunits, respectively. VirB2 is an essential component of T4SS, but the roles of VirB2 and the assembled T-pilus in Agrobacterium virulence and the T-DNA transfer process remain unknown. Here, we generated 34 VirB2 amino acid substitution variants to study the functions of VirB2 involved in VirB2 stability, extracellular VirB2/T-pilus production and virulence of A. tumefaciens. From the capacity for extracellular VirB2 production (ExB2+ or ExB2- and tumorigenesis on tomato stems (Vir+ or Vir-, the mutants could be classified into three groups: ExB2-/Vir-, ExB2-/Vir+, and ExB2+/Vir+. We also confirmed by electron microscopy that five ExB2-/Vir+ mutants exhibited a wild-type level of virulence with their deficiency in T-pilus formation. Interestingly, although the five T-pilus-/Vir+ uncoupling mutants retained a wild-type level of tumorigenesis efficiency on tomato stems and/or potato tuber discs, their transient transformation efficiency in Arabidopsis seedlings was highly attenuated. In conclusion, we have provided evidence for a role of T-pilus in Agrobacterium transformation process and have identified the domains and amino acid residues critical for VirB2 stability, T-pilus biogenesis, tumorigenesis, and transient transformation efficiency.

  4. Expression and Functional Characterization of the Agrobacterium VirB2 Amino Acid Substitution Variants in T-pilus Biogenesis, Virulence, and Transient Transformation Efficiency

    Science.gov (United States)

    Wu, Hung-Yi; Chen, Chao-Ying; Lai, Erh-Min

    2014-01-01

    Agrobacterium tumefaciens is a phytopathogenic bacterium that causes crown gall disease by transferring transferred DNA (T-DNA) into the plant genome. The translocation process is mediated by the type IV secretion system (T4SS) consisting of the VirD4 coupling protein and 11 VirB proteins (VirB1 to VirB11). All VirB proteins are required for the production of T-pilus, which consists of processed VirB2 (T-pilin) and VirB5 as major and minor subunits, respectively. VirB2 is an essential component of T4SS, but the roles of VirB2 and the assembled T-pilus in Agrobacterium virulence and the T-DNA transfer process remain unknown. Here, we generated 34 VirB2 amino acid substitution variants to study the functions of VirB2 involved in VirB2 stability, extracellular VirB2/T-pilus production and virulence of A. tumefaciens. From the capacity for extracellular VirB2 production (ExB2+ or ExB2−) and tumorigenesis on tomato stems (Vir+ or Vir−), the mutants could be classified into three groups: ExB2−/Vir−, ExB2−/Vir+, and ExB2+/Vir+. We also confirmed by electron microscopy that five ExB2−/Vir+ mutants exhibited a wild-type level of virulence with their deficiency in T-pilus formation. Interestingly, although the five T-pilus−/Vir+ uncoupling mutants retained a wild-type level of tumorigenesis efficiency on tomato stems and/or potato tuber discs, their transient transformation efficiency in Arabidopsis seedlings was highly attenuated. In conclusion, we have provided evidence for a role of T-pilus in Agrobacterium transformation process and have identified the domains and amino acid residues critical for VirB2 stability, T-pilus biogenesis, tumorigenesis, and transient transformation efficiency. PMID:24971727

  5. The association of virulence factors with genomic islands.

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    Shannan J Ho Sui

    2009-12-01

    Full Text Available It has been noted that many bacterial virulence factor genes are located within genomic islands (GIs; clusters of genes in a prokaryotic genome of probable horizontal origin. However, such studies have been limited to single genera or isolated observations. We have performed the first large-scale analysis of multiple diverse pathogens to examine this association. We additionally identified genes found predominantly in pathogens, but not non-pathogens, across multiple genera using 631 complete bacterial genomes, and we identified common trends in virulence for genes in GIs. Furthermore, we examined the relationship between GIs and clustered regularly interspaced palindromic repeats (CRISPRs proposed to confer resistance to phage.We show quantitatively that GIs disproportionately contain more virulence factors than the rest of a given genome (p<1E-40 using three GI datasets and that CRISPRs are also over-represented in GIs. Virulence factors in GIs and pathogen-associated virulence factors are enriched for proteins having more "offensive" functions, e.g. active invasion of the host, and are disproportionately components of type III/IV secretion systems or toxins. Numerous hypothetical pathogen-associated genes were identified, meriting further study.This is the first systematic analysis across diverse genera indicating that virulence factors are disproportionately associated with GIs. "Offensive" virulence factors, as opposed to host-interaction factors, may more often be a recently acquired trait (on an evolutionary time scale detected by GI analysis. Newly identified pathogen-associated genes warrant further study. We discuss the implications of these results, which cement the significant role of GIs in the evolution of many pathogens.

  6. A comparison of computational methods for identifying virulence factors.

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    Lu-Lu Zheng

    Full Text Available Bacterial pathogens continue to threaten public health worldwide today. Identification of bacterial virulence factors can help to find novel drug/vaccine targets against pathogenicity. It can also help to reveal the mechanisms of the related diseases at the molecular level. With the explosive growth in protein sequences generated in the postgenomic age, it is highly desired to develop computational methods for rapidly and effectively identifying virulence factors according to their sequence information alone. In this study, based on the protein-protein interaction networks from the STRING database, a novel network-based method was proposed for identifying the virulence factors in the proteomes of UPEC 536, UPEC CFT073, P. aeruginosa PAO1, L. pneumophila Philadelphia 1, C. jejuni NCTC 11168 and M. tuberculosis H37Rv. Evaluated on the same benchmark datasets derived from the aforementioned species, the identification accuracies achieved by the network-based method were around 0.9, significantly higher than those by the sequence-based methods such as BLAST, feature selection and VirulentPred. Further analysis showed that the functional associations such as the gene neighborhood and co-occurrence were the primary associations between these virulence factors in the STRING database. The high success rates indicate that the network-based method is quite promising. The novel approach holds high potential for identifying virulence factors in many other various organisms as well because it can be easily extended to identify the virulence factors in many other bacterial species, as long as the relevant significant statistical data are available for them.

  7. Prp43p Is a DEAH-Box Spliceosome Disassembly Factor Essential for Ribosome Biogenesis

    Science.gov (United States)

    Combs, D. Joshua; Nagel, Roland J.; Ares, Manuel; Stevens, Scott W.

    2006-01-01

    The known function of the DEXH/D-box protein Prp43p is the removal of the U2, U5, and U6 snRNPs from the postsplicing lariat-intron ribonucleoprotein complex. We demonstrate that affinity-purified Prp43p-associated material includes the expected spliceosomal components; however, we also identify several preribosomal complexes that are specifically purified with Prp43p. Conditional prp43 mutant alleles confer a 35S pre-rRNA processing defect, with subsequent depletion of 27S and 20S precursors. Upon a shift to a nonpermissive temperature, both large and small-ribosomal-subunit proteins accumulate in the nucleolus of prp43 mutants. Pulse-chase analysis demonstrates delayed kinetics of 35S, 27S, and 20S pre-rRNA processing with turnover of these intermediates. Microarray analysis of pre-mRNA splicing defects in prp43 mutants shows a very mild effect, similar to that of nonessential pre-mRNA splicing factors. Prp43p is the first DEXH/D-box protein shown to function in both RNA polymerase I and polymerase II transcript metabolism. Its essential function is in its newly characterized role in ribosome biogenesis of both ribosomal subunits, positioning Prp43p to regulate both pre-mRNA splicing and ribosome biogenesis. PMID:16382144

  8. [Virulence factors and pathophysiology of extraintestinal pathogenic Escherichia coli].

    Science.gov (United States)

    Bidet, P; Bonarcorsi, S; Bingen, E

    2012-11-01

    Extraintestinal pathogenic Escherichia coli (ExPEC) causing urinary tract infections, bacteraemia or meningitis are characterized by a particular genetic background (phylogenetic group B2 and D) and the presence, within genetic pathogenicity islands (PAI) or plasmids, of genes encoding virulence factors involved in adhesion to epithelia, crossing of the body barriers (digestive, kidney, bloodbrain), iron uptake and resistance to the immune system. Among the many virulence factors described, two are particularly linked with a pathophysiological process: type P pili PapGII adhesin is linked with acute pyelonephritis, in the absence of abnormal flow of urine, and the K1 capsule is linked with neonatal meningitis. However, if the adhesin PapGII appears as the key factor of pyelonephritis, such that its absence in strain causing the infection is predictive of malformation or a vesico-ureteral reflux, the meningeal virulence of E. coli can not be reduced to a single virulence factor, but results from a combination of factors unique to each clone, and an imbalance between the immune defenses of the host and bacterial virulence. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  9. Virulence Factors Associated with Enterococcus Faecalis Infective Endocarditis

    DEFF Research Database (Denmark)

    Madsen, Kristian T; Skov, Marianne N; Gill, Sabine

    2017-01-01

    been associated with E. faecalis infective endocarditis. Absence of these factors entailed attenuation of strains in both mixed- and mono-bacterial infection endocarditis models as well as in in vitro and ex vivo assays when compared to their virulence factor expressing parental strains. PATHOGENESIS......: The virulence factors promote a broad spectrum of events that together allow for disease development and progression. The infection is initiated through bacterial binding to ligands present at the site of infection after which the colonization can be accelerated through inter-bacterial attachment and modulation...

  10. Insights into mRNP biogenesis provided by new genetic interactions among export and transcription factors

    Directory of Open Access Journals (Sweden)

    Estruch Francisco

    2012-09-01

    Full Text Available Abstract Background The various steps of mRNP biogenesis (transcription, processing and export are interconnected. It has been shown that the transcription machinery plays a pivotal role in mRNP assembly, since several mRNA export factors are recruited during transcription and physically interact with components of the transcription machinery. Although the shuttling DEAD-box protein Dbp5p is concentrated on the cytoplasmic fibrils of the NPC, previous studies demonstrated that it interacts physically and genetically with factors involved in transcription initiation. Results We investigated the effect of mutations affecting various components of the transcription initiation apparatus on the phenotypes of mRNA export mutant strains. Our results show that growth and mRNA export defects of dbp5 and mex67 mutant strains can be suppressed by mutation of specific transcription initiation components, but suppression was not observed for mutants acting in the very first steps of the pre-initiation complex (PIC formation. Conclusions Our results indicate that mere reduction in the amount of mRNP produced is not sufficient to suppress the defects caused by a defective mRNA export factor. Suppression occurs only with mutants affecting events within a narrow window of the mRNP biogenesis process. We propose that reducing the speed with which transcription converts from initiation and promoter clearance to elongation may have a positive effect on mRNP formation by permitting more effective recruitment of partially-functional mRNP proteins to the nascent mRNP.

  11. A genome-wide screen for bacterial envelope biogenesis mutants identifies a novel factor involved in cell wall precursor metabolism.

    Directory of Open Access Journals (Sweden)

    Catherine Paradis-Bleau

    2014-01-01

    Full Text Available The cell envelope of Gram-negative bacteria is a formidable barrier that is difficult for antimicrobial drugs to penetrate. Thus, the list of treatments effective against these organisms is small and with the rise of new resistance mechanisms is shrinking rapidly. New therapies to treat Gram-negative bacterial infections are therefore sorely needed. This goal will be greatly aided by a detailed mechanistic understanding of envelope assembly. Although excellent progress in the identification of essential envelope biogenesis systems has been made in recent years, many aspects of the process remain to be elucidated. We therefore developed a simple, quantitative, and high-throughput assay for mutants with envelope biogenesis defects and used it to screen an ordered single-gene deletion library of Escherichia coli. The screen was robust and correctly identified numerous mutants known to be involved in envelope assembly. Importantly, the screen also implicated 102 genes of unknown function as encoding factors that likely impact envelope biogenesis. As a proof of principle, one of these factors, ElyC (YcbC, was characterized further and shown to play a critical role in the metabolism of the essential lipid carrier used for the biogenesis of cell wall and other bacterial surface polysaccharides. Further analysis of the function of ElyC and other hits identified in our screen is likely to uncover a wealth of new information about the biogenesis of the Gram-negative envelope and the vulnerabilities in the system suitable for drug targeting. Moreover, the screening assay described here should be readily adaptable to other organisms to study the biogenesis of different envelope architectures.

  12. Gallium induces the production of virulence factors in Pseudomonas aeruginosa.

    Science.gov (United States)

    García-Contreras, Rodolfo; Pérez-Eretza, Berenice; Lira-Silva, Elizabeth; Jasso-Chávez, Ricardo; Coria-Jiménez, Rafael; Rangel-Vega, Adrián; Maeda, Toshinari; Wood, Thomas K

    2014-02-01

    The novel antimicrobial gallium is a nonredox iron III analogue with bacteriostatic and bactericidal properties, effective for the treatment of Pseudomonas aeruginosa in vitro and in vivo in mouse and rabbit infection models. It interferes with iron metabolism, transport, and presumably its homeostasis. As gallium exerts its antimicrobial effects by competing with iron, we hypothesized that it ultimately will lead cells to an iron deficiency status. As iron deficiency promotes the expression of virulence factors in vitro and promotes the pathogenicity of P. aeruginosa in animal models, it is anticipated that treatment with gallium will also promote the production of virulence factors. To test this hypothesis, the reference strain PA14 and two clinical isolates from patients with cystic fibrosis were exposed to gallium, and their production of pyocyanin, rhamnolipids, elastase, alkaline protease, alginate, pyoverdine, and biofilm was determined. Gallium treatment induced the production of all the virulence factors tested in the three strains except for pyoverdine. In addition, as the Ga-induced virulence factors are quorum sensing controlled, co-administration of Ga and the quorum quencher brominated furanone C-30 was assayed, and it was found that C-30 alleviated growth inhibition from gallium. Hence, adding both C-30 and gallium may be more effective in the treatment of P. aeruginosa infections. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  13. Detection of some virulence factors in Staphylococcus aureus ...

    African Journals Online (AJOL)

    pathogens that can cause mastitis, Staphylococcus aureus is probably the most lethal agent because it causes chronic and deep infection in the mammary glands that is extremely difficult to be cured. The present study was to detect some of the virulence factors in the S. aureus isolated from 360 mastitis milk samples in ...

  14. A Strong Case for Viral Genetic Factors in HIV Virulence

    Directory of Open Access Journals (Sweden)

    Joshua T. Herbeck

    2011-03-01

    Full Text Available HIV infections show great variation in the rate of progression to disease, and the role of viral genetic factors in this variation had remained poorly characterized until recently. Now a series of four studies [1–4] published within a year has filled this important gap and has demonstrated a robust effect of the viral genotype on HIV virulence.

  15. Resistance and virulence factors of Escherichia coli isolated from chicken.

    Science.gov (United States)

    Pavlickova, Silvie; Dolezalova, Magda; Holko, Ivan

    2015-01-01

    Chicken meat has become an important part of the human diet and besides contamination by pathogenic Escherichia coli there is a risk of antibiotic resistance spreading via the food chain. The purpose of this study was to examine the prevalence of resistance against eight antibiotics and the presence of 14 virulence factors among 75 Escherichia coli strains isolated from chicken meat in the Czech Republic after classification into phylogenetic groups by the multiplex PCR method. More than half of strains belonged to A phylogroup, next frequently represented was B1 phylogroup, which suggests the commensal strains. The other strains were classified into phylogroups B2 and D, which had more virulence factors. Almost half of all E. coli strains were resistant to at least one of eight-tested antibiotics. A multidrug resistance was observed in 13% of strains. The most prevalent virulence genes were iucD, iss and tsh. None of genes encoding toxins was detected. Most of E. coli strains isolated from chicken meat can be considered as nonpathogenic on the basis of analysis of virulence factors, antibiotic resistance and phylogroups assignment. It can provide a useful tool for prediction of a potential risk from food contaminated by E. coli.

  16. Ribosome biogenesis and cancer.

    Science.gov (United States)

    Derenzini, Massimo; Montanaro, Lorenzo; Trerè, Davide

    2017-04-01

    There is growing evidence indicating that the human pathological conditions characterized by an up-regulated ribosome biogenesis are at an increased risk of cancer onset. At the basis of this relationship is the close interconnection between the ribosome biogenesis and cell proliferation. Cell proliferation-stimulating factors also stimulate ribosome production, while the ribosome biogenesis rate controls the cell cycle progression. The major tumour suppressor, the p53 protein, plays an important balancing role between the ribosome biogenesis rate and the cell progression through the cell cycle phases. The perturbation of ribosome biogenesis stabilizes and activates p53, with a consequent cell cycle arrest and/or apoptotic cell death, whereas an up-regulated ribosome production down-regulates p53 expression and activity, thus facilitating neoplastic transformation. In the present review we describe the interconnection between ribosome biogenesis and cell proliferation, while highlighting the mechanisms by which quantitative changes in ribosome biogenesis may induce cancer. Copyright © 2017 Elsevier GmbH. All rights reserved.

  17. The Central Metabolism Regulator EIIAGlc Switches Salmonella from Growth Arrest to Acute Virulence through Activation of Virulence Factor Secretion

    Directory of Open Access Journals (Sweden)

    Alain Mazé

    2014-06-01

    Full Text Available The ability of Salmonella to cause disease depends on metabolic activities and virulence factors. Here, we show that a key metabolic protein, EIIAGlc, is absolutely essential for acute infection, but not for Salmonella survival, in a mouse typhoid fever model. Surprisingly, phosphorylation-dependent EIIAGlc functions, including carbohydrate transport and activation of adenylate cyclase for global regulation, do not explain this virulence phenotype. Instead, biochemical studies, in vitro secretion and translocation assays, and in vivo genetic epistasis experiments suggest that EIIAGlc binds to the type three secretion system 2 (TTSS-2 involved in systemic virulence, stabilizes its cytoplasmic part including the crucial TTSS-2 ATPase, and activates virulence factor secretion. This unexpected role of EIIAGlc reveals a striking direct link between central Salmonella metabolism and a crucial virulence mechanism.

  18. Giant peroxisomes in a moss (Physcomitrella patens) peroxisomal biogenesis factor 11 mutant.

    Science.gov (United States)

    Kamisugi, Yasuko; Mitsuya, Shiro; El-Shami, Mahmoud; Knight, Celia D; Cuming, Andrew C; Baker, Alison

    2016-01-01

    Peroxisomal biogenesis factor 11 (PEX11) proteins are found in yeasts, mammals and plants, and play a role in peroxisome morphology and regulation of peroxisome division. The moss Physcomitrella patens has six PEX11 isoforms which fall into two subfamilies, similar to those found in monocots and dicots. We carried out targeted gene disruption of the Phypa_PEX11-1 gene and compared the morphological and cellular phenotypes of the wild-type and mutant strains. The mutant grew more slowly and the development of gametophores was retarded. Mutant chloronemal filaments contained large cellular structures which excluded all other cellular organelles. Expression of fluorescent reporter proteins revealed that the mutant strain had greatly enlarged peroxisomes up to 10 μm in diameter. Expression of a vacuolar membrane marker confirmed that the enlarged structures were not vacuoles, or peroxisomes sequestered within vacuoles as a result of pexophagy. Phypa_PEX11 targeted to peroxisome membranes could rescue the knock out phenotype and interacted with Fission1 on the peroxisome membrane. Moss PEX11 functions in peroxisome division similar to PEX11 in other organisms but the mutant phenotype is more extreme and environmentally determined, making P. patens a powerful system in which to address mechanisms of peroxisome proliferation and division. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  19. Inhibition of Cronobacter sakazakii Virulence Factors by Citral

    OpenAIRE

    Shi, Chao; Sun, Yi; Liu, Zhiyuan; Guo, Du; Sun, Huihui; Sun, Zheng; Chen, Shan; Zhang, Wenting; Wen, Qiwu; Peng, Xiaoli; Xia, Xiaodong

    2017-01-01

    Cronobacter sakazakii is a foodborne pathogen associated with fatal forms of necrotizing enterocolitis, meningitis and sepsis in neonates and infants. The aim of this study was to determine whether citral, a major component of lemongrass oil, could suppress putative virulence factors of C. sakazakii that contribute to infection. Sub-inhibitory concentrations of citral significantly decreased motility, quorum sensing, biofilm formation and endotoxin production. Citral substantially reduced the...

  20. Inhibition of Cronobacter sakazakii Virulence Factors by Citral.

    Science.gov (United States)

    Shi, Chao; Sun, Yi; Liu, Zhiyuan; Guo, Du; Sun, Huihui; Sun, Zheng; Chen, Shan; Zhang, Wenting; Wen, Qiwu; Peng, Xiaoli; Xia, Xiaodong

    2017-02-24

    Cronobacter sakazakii is a foodborne pathogen associated with fatal forms of necrotizing enterocolitis, meningitis and sepsis in neonates and infants. The aim of this study was to determine whether citral, a major component of lemongrass oil, could suppress putative virulence factors of C. sakazakii that contribute to infection. Sub-inhibitory concentrations of citral significantly decreased motility, quorum sensing, biofilm formation and endotoxin production. Citral substantially reduced the adhesion and invasion of C. sakazakii to Caco-2 cells and decreased bacterial survival and replication within the RAW 264.7 macrophage cells. Citral also repressed the expression of eighteen genes involved in the virulence. These findings suggest that citral has potential to be developed as an alternative or supplemental agent to mitigate the infections caused by C. sakazakii.

  1. Expression of bacterial Rho factor in yeast identifies new factors involved in the functional interplay between transcription and mRNP biogenesis.

    Science.gov (United States)

    Mosrin-Huaman, Christine; Honorine, Romy; Rahmouni, A Rachid

    2009-08-01

    In eukaryotic cells, the nascent pre-mRNA molecule is coated sequentially with a large set of processing and binding proteins that mediate its transformation into an export-competent ribonucleoprotein particle (mRNP) that is ready for translation in the cytoplasm. We have implemented an original assay that monitors the dynamic interplay between transcription and mRNP biogenesis and that allows the screening for new factors linking mRNA synthesis to translation in Saccharomyces cerevisiae. The assay is based on the perturbation of gene expression induced by the bacterial Rho factor, an RNA-dependent helicase/translocase that acts as a competitor at one or several steps of mRNP biogenesis in yeast. We show that the expression of Rho in yeast leads to a dose-dependent growth defect that stems from its action on RNA polymerase II-mediated transcription. Rho expression induces the production of aberrant transcripts that are degraded by the nuclear exosome. A screen for dosage suppressors of the Rho-induced growth defect identified several genes that are involved in the different steps of mRNP biogenesis and export, as well as other genes with both known functions in transcription regulation and unknown functions. Our results provide evidence for an extensive cross talk between transcription, mRNP biogenesis, and export. They also uncover new factors that potentially are involved in these interconnected events.

  2. [Main virulence factors of Listeria monocytogenes and its regulation].

    Science.gov (United States)

    Vera, Alejandra; González, Gerardo; Domínguez, Mariana; Bello, Helia

    2013-08-01

    Listeria monocytogenesis a facultative intracellular pathogen, ubiquitous and aetiological agent of listeriosis. The main way of acquisition is the consumption of contaminated food and can cause serious medical conditions such as septicemia, meningitis and gastroenteritis, especially in children, immunocompromised individuals and seniors and abortions in pregnant women. An increase in cases of listeriosis worldwide has been reported and it is estimated that its prevalence in developed countries is in the range of 2 to 15 cases per one million population. This microorganism is characterized for the transition from the environment into the eukaryotic cell. Several virulence factors have been involved in the intracellular cycle that are regulated, primarily, by the PrfA protein, which in turn is regulated by different mechanisms operating at the transcriptional, translational and post-translational levels. Additionally, other regulatory mechanisms have been described as sigma factor, system VirR/S and antisense RNA, but PrfA is the most important control mechanism and is required for the expression of essential virulence factors for the intracellular cycle.

  3. Tissue specific roles for the ribosome biogenesis factor Wdr43 in zebrafish development.

    Directory of Open Access Journals (Sweden)

    Chengtian Zhao

    2014-01-01

    Full Text Available During vertebrate craniofacial development, neural crest cells (NCCs contribute to most of the craniofacial pharyngeal skeleton. Defects in NCC specification, migration and differentiation resulting in malformations in the craniofacial complex are associated with human craniofacial disorders including Treacher-Collins Syndrome, caused by mutations in TCOF1. It has been hypothesized that perturbed ribosome biogenesis and resulting p53 mediated neuroepithelial apoptosis results in NCC hypoplasia in mouse Tcof1 mutants. However, the underlying mechanisms linking ribosome biogenesis and NCC development remain poorly understood. Here we report a new zebrafish mutant, fantome (fan, which harbors a point mutation and predicted premature stop codon in zebrafish wdr43, the ortholog to yeast UTP5. Although wdr43 mRNA is widely expressed during early zebrafish development, and its deficiency triggers early neural, eye, heart and pharyngeal arch defects, later defects appear fairly restricted to NCC derived craniofacial cartilages. Here we show that the C-terminus of Wdr43, which is absent in fan mutant protein, is both necessary and sufficient to mediate its nucleolar localization and protein interactions in metazoans. We demonstrate that Wdr43 functions in ribosome biogenesis, and that defects observed in fan mutants are mediated by a p53 dependent pathway. Finally, we show that proper localization of a variety of nucleolar proteins, including TCOF1, is dependent on that of WDR43. Together, our findings provide new insight into roles for Wdr43 in development, ribosome biogenesis, and also ribosomopathy-induced craniofacial phenotypes including Treacher-Collins Syndrome.

  4. Pathogenicity, Epidemiology and Virulence Factors of Salmonella species: A Review

    Directory of Open Access Journals (Sweden)

    Tamègnon Victorien DOUGNON

    2017-12-01

    Full Text Available Salmonella infections are major public health problems worldwide. The hereby review aimed to establish an overview on the pathogenicity, epidemiology and virulence factors of Salmonella spp. in the world. A systematic search was conducted online using the keywords ‘Salmonella’, ‘Salmonella spp.’, ‘Salmonella spp. Epidemiology’, ‘virulence factors of Salmonella spp. in the world’, ‘bacteria responsible for the contamination of meat products’, ‘non-typhoid salmonella’. These keywords were entered into databases such as PubMed and Google Scholar using mainly French language. The obtained articles were included based on the reliability of their source, the study area (usually Benin and Africa and the subject. The review revealed that Salmonella spp. is motile Gram-negative rod-shaped bacteria, of the family Enterobacteriaceae, currently counting more than 2,600 serovars. Human contamination occurs through the ingestion of contaminated water and food and can cause gastroenteritis or typhoid fever, which are two serious public health problems. A gene set constituting the pathogenicity islands determines the pathogenesis of Salmonella spp. The diagnosis is based on bacteriological, serological and molecular techniques. Salmonella infections are usually treated using antibiotics; however, emergence of antibiotic resistance in these microorganisms suggests that the anti-salmonella control should explore new sources such as medicinal plants

  5. Interrelationships between yeast ribosomal protein assembly events and transient ribosome biogenesis factors interactions in early pre-ribosomes.

    Science.gov (United States)

    Jakob, Steffen; Ohmayer, Uli; Neueder, Andreas; Hierlmeier, Thomas; Perez-Fernandez, Jorge; Hochmuth, Eduard; Deutzmann, Rainer; Griesenbeck, Joachim; Tschochner, Herbert; Milkereit, Philipp

    2012-01-01

    Early steps of eukaryotic ribosome biogenesis require a large set of ribosome biogenesis factors which transiently interact with nascent rRNA precursors (pre-rRNA). Most likely, concomitant with that initial contacts between ribosomal proteins (r-proteins) and ribosome precursors (pre-ribosomes) are established which are converted into robust interactions between pre-rRNA and r-proteins during the course of ribosome maturation. Here we analysed the interrelationship between r-protein assembly events and the transient interactions of ribosome biogenesis factors with early pre-ribosomal intermediates termed 90S pre-ribosomes or small ribosomal subunit (SSU) processome in yeast cells. We observed that components of the SSU processome UTP-A and UTP-B sub-modules were recruited to early pre-ribosomes independently of all tested r-proteins. On the other hand, groups of SSU processome components were identified whose association with early pre-ribosomes was affected by specific r-protein assembly events in the head-platform interface of the SSU. One of these components, Noc4p, appeared to be itself required for robust incorporation of r-proteins into the SSU head domain. Altogether, the data reveal an emerging network of specific interrelationships between local r-protein assembly events and the functional interactions of SSU processome components with early pre-ribosomes. They point towards some of these components being transient primary pre-rRNA in vivo binders and towards a role for others in coordinating the assembly of major SSU domains.

  6. Insulin-like growth factor 1 signaling is essential for mitochondrial biogenesis and mitophagy in cancer cells.

    Science.gov (United States)

    Lyons, Amy; Coleman, Michael; Riis, Sarah; Favre, Cedric; O'Flanagan, Ciara H; Zhdanov, Alexander V; Papkovsky, Dmitri B; Hursting, Stephen D; O'Connor, Rosemary

    2017-10-13

    Mitochondrial activity and metabolic reprogramming influence the phenotype of cancer cells and resistance to targeted therapy. We previously established that an insulin-like growth factor 1 (IGF-1)-inducible mitochondrial UTP carrier (PNC1/SLC25A33) promotes cell growth. This prompted us to investigate whether IGF signaling is essential for mitochondrial maintenance in cancer cells and whether this contributes to therapy resistance. Here we show that IGF-1 stimulates mitochondrial biogenesis in a range of cell lines. In MCF-7 and ZR75.1 breast cancer cells, IGF-1 induces peroxisome proliferator-activated receptor γ coactivator 1β (PGC-1β) and PGC-1α-related coactivator (PRC). Suppression of PGC-1β and PRC with siRNA reverses the effects of IGF-1 and disrupts mitochondrial morphology and membrane potential. IGF-1 also induced expression of the redox regulator nuclear factor-erythroid-derived 2-like 2 (NFE2L2 alias NRF-2). Of note, MCF-7 cells with acquired resistance to an IGF-1 receptor (IGF-1R) tyrosine kinase inhibitor exhibited reduced expression of PGC-1β, PRC, and mitochondrial biogenesis. Interestingly, these cells exhibited mitochondrial dysfunction, indicated by reactive oxygen species expression, reduced expression of the mitophagy mediators BNIP3 and BNIP3L, and impaired mitophagy. In agreement with this, IGF-1 robustly induced BNIP3 accumulation in mitochondria. Other active receptor tyrosine kinases could not compensate for reduced IGF-1R activity in mitochondrial protection, and MCF-7 cells with suppressed IGF-1R activity became highly dependent on glycolysis for survival. We conclude that IGF-1 signaling is essential for sustaining cancer cell viability by stimulating both mitochondrial biogenesis and turnover through BNIP3 induction. This core mitochondrial protective signal is likely to strongly influence responses to therapy and the phenotypic evolution of cancer. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  7. Liposomes as novel anti-infectives targeting bacterial virulence factors?

    Science.gov (United States)

    Azeredo da Silveira, Samareh; Perez, Antonio

    2015-05-01

    A recent report commissioned by Prime Minister David Cameron and chaired by former Goldman Sachs chief economist Jim O'Neill warns that the emergence, persistence and spread of antimicrobial resistance could lead to 10 million deaths per year and cause an economic burden as much as US$100 trillion by 2050. In the midst of this global crisis, unprecedented paths are being explored to combat bacterial infection. Virulence factors, and more particularly pore-forming toxins, play a key role in increasing morbidity and mortality caused by drug-resistant bacterial infections. Novel anti-infective liposomes specifically targeting and neutralizing these cytotoxic toxins are potential game-changers in the fight against deadly infections.

  8. Pasteurella multocida virulence factors: selection of fowl cholera-inducing and non-inducing strains.

    Science.gov (United States)

    Rhoades, K R; Rimler, R B

    1993-01-01

    Relatively little information is available on Pasteurella multocida virulence factors involved in producing fowl cholera. Because of the complex nature of bacterial pathogenesis, the recommended approach for ascertaining these factors is to compare biological attributes of high- and low-virulence strains. To permit use of this approach for fowl cholera, P. multocida strains of high and low virulence were identified. Turkey poults were exposed intrapharyngeally and intravenously (IV) to two antigenically and biochemically similar strains. Based on mortality, strain P-1059 was highly virulent and strain P-1062 was avirulent. Microbiological examination indicated that only the virulent strain infected the pharyngeal mucosa of intrapharyngeally exposed poults and survived and multiplied in IV-exposed poults. These findings indicate strain differences in those virulence factors concerned with the colonization and multiplication stages of disease development.

  9. The determination of Exserohilum turcicum virulence factors in Serbia

    Directory of Open Access Journals (Sweden)

    Lević Jelena

    2008-01-01

    Full Text Available The determination of Exserohilum turcicum virulence factors and resistance responses of three sets of maize inbred lines (four differential, eight isogenic and 22 commercial inbreeds to three isolates of this pathogen under greenhouse conditions were studied. The maize inbreeds were selected according to previous testing of resistance based on lesion types in 194 inbreeds under field conditions of plant inoculation with the E. turcicum race 0 (designated as the isolate MRI-Et. The standard procedure was applied to obtained isolates MRIZP-1747 and MRIZP-1416 from resistant and susceptible lesion types, respectively. These lesions were developed on the same leaf of a plant of the experimental hybrid no. 163/99 grown in a nursery at Zemun Polje during 1999. The third isolate (MRIZP-1435 was isolated from a leaf sample originating from the location of Srbobran in which the occurrence of northern corn leaf blight (NCLB, caused by Exserohilum turcicum, was intensive. Based upon virulence/avirulence of three isolates of E. turcicum on differential maize inbred lines, it was found out that the isolate MRIZP-1747 could be classified as race 0, whereas isolates MRIZP-1416 and MRIZP-1435 could be classified as race 1. These are the first results that confirm the presence of race 1 of E. turcicum in Serbia. Not including differential lines, 22 and six lines were resistant to race 0 and race 1, respectively, while eight and five lines were resistant and susceptible to both races, respectively. All isogenic lines not containing the Ht gene were susceptible to both races 0 and 1.

  10. From self sufficiency to dependence: mechanisms and factors important for autotransporter biogenesis.

    Science.gov (United States)

    Leyton, Denisse L; Rossiter, Amanda E; Henderson, Ian R

    2012-02-16

    Autotransporters are a superfamily of proteins that use the type V secretion pathway for their delivery to the surface of Gram-negative bacteria. At first glance, autotransporters look to contain all the functional elements required to promote their own secretion: an amino-terminal signal peptide to mediate translocation across the inner membrane, a central passenger domain that is the secreted functional moiety, and a channel-forming carboxyl terminus that facilitates passenger domain translocation across the outer membrane. However, recent discoveries of common structural themes, translocation intermediates and accessory interactions have challenged the perceived simplicity of autotransporter secretion. Here, we discuss how these studies have led to an improved understanding of the mechanisms responsible for autotransporter biogenesis.

  11. Cockayne syndrome protein A is a transcription factor of RNA polymerase I and stimulates ribosomal biogenesis and growth.

    Science.gov (United States)

    Koch, Sylvia; Garcia Gonzalez, Omar; Assfalg, Robin; Schelling, Adrian; Schäfer, Patrick; Scharffetter-Kochanek, Karin; Iben, Sebastian

    2014-01-01

    Mutations in the Cockayne syndrome A (CSA) protein account for 20% of Cockayne syndrome (CS) cases, a childhood disorder of premature aging and early death. Hitherto, CSA has exclusively been described as DNA repair factor of the transcription-coupled branch of nucleotide excision repair. Here we show a novel function of CSA as transcription factor of RNA polymerase I in the nucleolus. Knockdown of CSA reduces pre-rRNA synthesis by RNA polymerase I. CSA associates with RNA polymerase I and the active fraction of the rDNA and stimulates re-initiation of rDNA transcription by recruiting the Cockayne syndrome proteins TFIIH and CSB. Moreover, compared with CSA deficient parental CS cells, CSA transfected CS cells reveal significantly more rRNA with induced growth and enhanced global translation. A previously unknown global dysregulation of ribosomal biogenesis most likely contributes to the reduced growth and premature aging of CS patients.

  12. MicroRNAs upregulated during HIV infection target peroxisome biogenesis factors: Implications for virus biology, disease mechanisms and neuropathology.

    Directory of Open Access Journals (Sweden)

    Zaikun Xu

    2017-06-01

    Full Text Available HIV-associated neurocognitive disorders (HAND represent a spectrum neurological syndrome that affects up to 25% of patients with HIV/AIDS. Multiple pathogenic mechanisms contribute to the development of HAND symptoms including chronic neuroinflammation and neurodegeneration. Among the factors linked to development of HAND is altered expression of host cell microRNAs (miRNAs in brain. Here, we examined brain miRNA profiles among HIV/AIDS patients with and without HAND. Our analyses revealed differential expression of 17 miRNAs in brain tissue from HAND patients. A subset of the upregulated miRNAs (miR-500a-5p, miR-34c-3p, miR-93-3p and miR-381-3p, are predicted to target peroxisome biogenesis factors (PEX2, PEX7, PEX11B and PEX13. Expression of these miRNAs in transfected cells significantly decreased levels of peroxisomal proteins and concomitantly decreased peroxisome numbers or affected their morphology. The levels of miR-500a-5p, miR-34c-3p, miR-93-3p and miR-381-3p were not only elevated in the brains of HAND patients, but were also upregulated during HIV infection of primary macrophages. Moreover, concomitant loss of peroxisomal proteins was observed in HIV-infected macrophages as well as in brain tissue from HIV-infected patients. HIV-induced loss of peroxisomes was abrogated by blocking the functions of the upregulated miRNAs. Overall, these findings point to previously unrecognized miRNA expression patterns in the brains of HIV patients. Targeting peroxisomes by up-regulating miRNAs that repress peroxisome biogenesis factors may represent a novel mechanism by which HIV-1 subverts innate immune responses and/or causes neurocognitive dysfunction.

  13. Molecular characterization of virulence factors in Aeromonas hydrophila obtained from fish

    Directory of Open Access Journals (Sweden)

    Samira T.L. Oliveira

    2012-08-01

    Full Text Available Multiple factors can be involved in the virulence processes of Aeromonas hydrophila. The objective of the present paper was to verify the presence of aerolysin, hidrolipase, elastase and lipase virulence genes through the polymerase chain reaction (PCR in A. hydrophila isolates obtained from fish of the São Francisco River Valley, and to evaluate virulence according to the presence of these genes in Nile tilapia fingerlings. One hundred and fourteen isolates from the bacteria were used. DNA was heat extracted and PCR undertaken using specific primers described in the literature. For in vivo tests Nile tilapia fingerlings were used. From the PCR tests, negative isolates for all genes tested were selected, positive isolates for two genes (aerolysin and elastase and positive for the four genes tested. These were inoculated at a concentration of 10(8 UFC/ml into the tilapias, considered as treatments; another group of animals was used as control (with inoculation of saline solution. In all, 12 distinct standards regarding the presence of virulence factors in isolates from A. hydrophila, were observed. Of the 114 isolates analyzed, 100 (87.72% presented at least one of the virulence factors under study. The virulence factors were widely distributed among the A. hydrophila isolates. Aerolysin was the most frequent virulence factor present in the isolates analyzed. A. hydrophila led to the mortality of the Nile tilapia fingerlings, regardless of the absence or quantity of virulence genes tested.

  14. Amoebapore is an important virulence factor of Entamoeba histolytica

    Indian Academy of Sciences (India)

    We have previously demonstrated that inhibition of expression of amoebapore A (AP-A) by antisense RNA caused a marked decrease in the virulence of the parasite. A four-fold over-expression of AP-A was obtained with plasmid (pA7) which has the ap-a gene under the control of gene EhgLE-3-RP-L21. The virulence of ...

  15. Possible virulence factors of Aeromonas spp. from food and water.

    Science.gov (United States)

    Granum, P E; O'Sullivan, K; Tomás, J M; Ormen, O

    1998-06-01

    Thirty-one isolates of Aeromonas spp. from food and water in Norway were classified and tested for possible virulence factors including cytotoxins (tissue cultures, PCR), enterotoxins (PCR) and invasion ability (Caco-2 cells). Five different species were recorded, A. caviae (9/31), A. hydrophila (15/31), A. schubertii (3/31), A. trota (3/31) and A. veronii biovar veronii (1/31). One of the A. hydrophila strains was probably responsible for a small outbreak of food poisoning caused by ingestion of raw fermented fish. All the A. hydrophila strains produced and secreted cytotoxins at 37 degrees C, as well as two A. trota strains and the single A. veronii biovar veronii strain. In some cases increased cytotoxin secretion was observed under osmotic stress. The majority of the A. caviae strains which produced cytotoxins at 30 degrees C were unable to produce and/or secrete cytotoxins at 37 degrees C. One A. schubertii strain and one A. caviae strain were invasive.

  16. Biotypes and virulence factors of Gardnerella vaginalis isolated from cases of bacterial vaginosis.

    Science.gov (United States)

    Udayalaxmi, J; Bhat, G K; Kotigadde, S

    2011-01-01

    The present study was conducted to correlate the biotypes of Gardnerella vaginalis strains isolated from cases of bacterial vaginosis and their virulence factors. Thirty-two strains of G. vaginalis isolated from cases of bacterial vaginosis were biotyped. Adherence to vaginal epithelial cells, biofilm production, surface hydrophobicity, phospholipase C and protease activity were tested on these isolates. Biotype 1 was the most prevalent (8; 25%), followed by biotype 2 (7; 21.9%) and biotypes 5 and 8 (5; 15.6%). We did not find any statistical correlation between G. vaginalis biotypes and its virulence factors. Virulence factors expressed by G. vaginalis were not associated with a single biotype.

  17. Reconstruction of the metabolic network of Pseudomonas aeruginosa to interrogate virulence factor synthesis

    Science.gov (United States)

    Bartell, Jennifer A.; Blazier, Anna S.; Yen, Phillip; Thøgersen, Juliane C.; Jelsbak, Lars; Goldberg, Joanna B.; Papin, Jason A.

    2017-03-01

    Virulence-linked pathways in opportunistic pathogens are putative therapeutic targets that may be associated with less potential for resistance than targets in growth-essential pathways. However, efficacy of virulence-linked targets may be affected by the contribution of virulence-related genes to metabolism. We evaluate the complex interrelationships between growth and virulence-linked pathways using a genome-scale metabolic network reconstruction of Pseudomonas aeruginosa strain PA14 and an updated, expanded reconstruction of P. aeruginosa strain PAO1. The PA14 reconstruction accounts for the activity of 112 virulence-linked genes and virulence factor synthesis pathways that produce 17 unique compounds. We integrate eight published genome-scale mutant screens to validate gene essentiality predictions in rich media, contextualize intra-screen discrepancies and evaluate virulence-linked gene distribution across essentiality datasets. Computational screening further elucidates interconnectivity between inhibition of virulence factor synthesis and growth. Successful validation of selected gene perturbations using PA14 transposon mutants demonstrates the utility of model-driven screening of therapeutic targets.

  18. Clostridial pore-forming toxins: powerful virulence factors.

    Science.gov (United States)

    Popoff, Michel R

    2014-12-01

    Pore formation is a common mechanism of action for many bacterial toxins. More than one third of clostridial toxins are pore-forming toxins (PFTs) belonging to the β-PFT class. They are secreted as soluble monomers rich in β-strands, which recognize a specific receptor on target cells and assemble in oligomers. Then, they undergo a conformational change leading to the formation of a β-barrel, which inserts into the lipid bilayer forming functional pore. According to their structure, clostridial β-PFTs are divided into several families. Clostridial cholesterol-dependent cytolysins form large pores, which disrupt the plasma membrane integrity. They are potent virulence factors mainly involved in myonecrosis. Clostridial heptameric β-PFTs (aerolysin family and staphylococcal α-hemolysin family) induce small pores which trigger signaling cascades leading to different cell responses according to the cell types and toxins. They are mainly responsible for intestinal diseases, like necrotic enteritis, or systemic diseases/toxic shock from intestinal origin. Clostridial intracellularly active toxins exploit pore formation through the endosomal membrane to translocate the enzymatic component or domain into the cytosol. Single chain protein toxins, like botulinum and tetanus neurotoxins, use hydrophobic α-helices to form pores, whereas clostridial binary toxins encompass binding components, which are structurally and functionally related to β-PFTs, but which have acquired the specific activity to internalize their corresponding enzymatic components. Structural analysis suggests that β-PFTs and binding components share a common evolutionary origin. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Phospholipase A1: a novel virulence factor in Trypanosoma cruzi.

    Science.gov (United States)

    Belaunzarán, María Laura; Wilkowsky, Silvina Elizabeth; Lammel, Estela María; Giménez, Guadalupe; Bott, Emanuel; Barbieri, Manuel Alejandro; de Isola, Elvira Luisa Durante

    2013-02-01

    Phospholipase A1 (PLA1) has been described in the infective stages of Trypanosoma cruzi as a membrane-bound/secreted enzyme that significantly modified host cell lipid profile with generation of second lipid messengers and concomitant activation of protein kinase C. In the present work we determined higher levels of PLA1 expression in the infective amastigotes and trypomastigotes than in the non-infective epimastigotes of lethal RA strain. In addition, we found similar expression patterns but distinct PLA1 activity levels in bloodstream trypomastigotes from Cvd and RA (lethal) and K98 (non-lethal) T. cruzi strains, obtained at their corresponding parasitemia peaks. This fact was likely due to the presence of different levels of anti-T. cruzi PLA1 antibodies in sera of infected mice, that modulated the enzyme activity. Moreover, these antibodies significantly reduced in vitro parasite invasion indicating the participation of T. cruzi PLA1 in the early events of parasite-host cell interaction. We also demonstrated the presence of lysophospholipase activity in live infective stages that could account for self-protection against the toxic lysophospholipids generated by T. cruzi PLA1 action. At the genome level, we identified at least eight putative genes that codify for T. cruzi PLA1 with high amino acid sequence variability in their amino and carboxy-terminal regions; a putative PLA1 selected gene was cloned and expressed as a recombinant protein that possessed PLA1 activity. Collectively, the results presented here point out at T. cruzi PLA1 as a novel virulence factor implicated in parasite invasion. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Random T-DNA mutagenesis identifies a Cu-Zn-superoxide dismutase gene as a virulence factor of Sclerotinia sclerotiorum

    Science.gov (United States)

    Agrobacterium-mediated transformation (AMT) was used to identify potential virulence factors in Sclerotinia sclerotiorum. Screening AMT transformants identified two mutants showing significantly reduced virulence. The mutants showed similar growth rate, colony morphology, and sclerotial and oxalate ...

  1. Characteristics of the biologically active 35-kDa metalloprotease virulence factor from Listeria monocytogenes

    NARCIS (Netherlands)

    Coffey, A; van den Burg, B; Veltman, R; Abee, T

    Listeria monocytogenes, a facultative intracellular pathogen, synthesizes an extracellular protease which is responsible for the maturation of phosphatidylcholine phospholipase C (lecithinase), a virulence factor involved in cell-to-cell spread. This work describes the environmental parameters

  2. Global analysis of the impact of linezolid onto virulence factor production in S. aureus USA300

    NARCIS (Netherlands)

    Bonn, Florian; Pane-Farre, Jan; Schlueter, Rabea; Schaffer, Marc; Fuchs, Stephan; Bernhardt, Joerg; Riedel, Katharina; Otto, Andreas; Voelker, Uwe; van Dijl, Jan Maarten; Hecker, Michael; Maeder, Ulrike; Becher, Doerte

    The translation inhibitor linezolid is an antibiotic of last resort against Gram-positive pathogens including methicillin resistant strains of the nosocomial pathogen Staphylococcus aureus. Linezolid is reported to inhibit production of extracellular virulence factors, but the molecular cause is

  3. Communication between microorganisms as a basis for production of virulence factors.

    Science.gov (United States)

    Gospodarek, Eugenia; Bogiel, Tomasz; Zalas-Wiecek, Patrycja

    2009-01-01

    Quorum sensing (QS), or cell-to-cell communication in bacteria, is achieved through the production and subsequent response to the accumulation of extracellular signal molecules called autoinductors. The main role of QS is regulation of production of virulence factors in bacteria. Bacterial pathogenicity is often manifested by the expression of various cell-associated and secreted virulence factors, such as exoenzymes, toxins and biofilm. In bacteria, the expression of virulence factors is controlled coordinately by the global regulatory QS systems, which includes the AI-1/LuxIR-, AI-2/LuxS-, AI-3/QsC-, AIP/Agr-based systems. The regulation of production of virulence factors is extremely complex and many components influence it.

  4. Inactivation of staphylococcal virulence factors using a light-activated antimicrobial agent

    Directory of Open Access Journals (Sweden)

    Wilson Michael

    2009-10-01

    Full Text Available Abstract Background One of the limitations of antibiotic therapy is that even after successful killing of the infecting microorganism, virulence factors may still be present and cause significant damage to the host. Light-activated antimicrobials show potential for the treatment of topical infections; therefore if these agents can also inactivate microbial virulence factors, this would represent an advantage over conventional antibiotic therapy. Staphylococcus aureus produces a wide range of virulence factors that contribute to its success as a pathogen by facilitating colonisation and destruction of host tissues. Results In this study, the ability of the light-activated antimicrobial agent methylene blue in combination with laser light of 665 nm to inactivate staphylococcal virulence factors was assessed. A number of proteinaceous virulence factors were exposed to laser light in the presence of methylene blue and their biological activities re-determined. The activities of V8 protease, α-haemolysin and sphingomyelinase were shown to be inhibited in a dose-dependent manner by exposure to laser light in the presence of methylene blue. Conclusion These results suggest that photodynamic therapy could reduce the harmful impact of preformed virulence factors on the host.

  5. Long-distance delivery of bacterial virulence factors by Pseudomonas aeruginosa outer membrane vesicles.

    Directory of Open Access Journals (Sweden)

    Jennifer M Bomberger

    2009-04-01

    Full Text Available Bacteria use a variety of secreted virulence factors to manipulate host cells, thereby causing significant morbidity and mortality. We report a mechanism for the long-distance delivery of multiple bacterial virulence factors, simultaneously and directly into the host cell cytoplasm, thus obviating the need for direct interaction of the pathogen with the host cell to cause cytotoxicity. We show that outer membrane-derived vesicles (OMV secreted by the opportunistic human pathogen Pseudomonas aeruginosa deliver multiple virulence factors, including beta-lactamase, alkaline phosphatase, hemolytic phospholipase C, and Cif, directly into the host cytoplasm via fusion of OMV with lipid rafts in the host plasma membrane. These virulence factors enter the cytoplasm of the host cell via N-WASP-mediated actin trafficking, where they rapidly distribute to specific subcellular locations to affect host cell biology. We propose that secreted virulence factors are not released individually as naked proteins into the surrounding milieu where they may randomly contact the surface of the host cell, but instead bacterial derived OMV deliver multiple virulence factors simultaneously and directly into the host cell cytoplasm in a coordinated manner.

  6. Plant-derived antimicrobials reduce Listeria monocytogenes virulence factors in vitro, and down-regulate expression of virulence genes.

    Science.gov (United States)

    Upadhyay, Abhinav; Johny, Anup Kollanoor; Amalaradjou, Mary Anne Roshni; Ananda Baskaran, Sangeetha; Kim, Kwang Sik; Venkitanarayanan, Kumar

    2012-06-15

    Listeria monocytogenes (LM) is a major foodborne pathogen causing septicemia, meningitis and death in humans. LM infection is preceded by its attachment to and invasion of human intestinal epithelium followed by systemic spread. The major virulence factors in LM include motility, hemolysin and lecithinase production. Reducing LM attachment to and invasion of host tissue and production of virulence factors could potentially control listeriosis in humans. This study investigated the efficacy of sub-inhibitory concentrations (SICs, concentrations not inhibiting bacterial growth) of three, generally regarded as safe (GRAS)-status, plant-derived antimicrobial compounds in reducing LM attachment to and invasion of human colon adenocarcinoma (Caco-2) and human brain microvascular endothelial cells (HBMEC). Additionally, the effect of these compounds on the aforementioned LM virulence factors was studied. The compounds and their respective SICs used relative to their MICs were trans-cinnamaldehyde (TC 0.50mM, 0.75mM with the MIC of 0.90mM), carvacrol (CR 0.50mM, 0.65mM with the MIC of 0.75mM), and thymol (TY 0.33mM, 0.50mM with the MIC of 0.60mM). All three-plant antimicrobials reduced LM adhesion to and invasion of Caco-2 and HBMEC (p3.0 folds compared to controls (p<0.05). Results suggest that TC, CR, and TY could potentially be used to control LM infection; however, in vivo studies are necessary to validate these results. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. [Investigation of some virulence factors in Trichosporon spp. strains].

    Science.gov (United States)

    Demir, Feyza; Kuştimur, Semra

    2014-10-01

    The frequency of fungal infections have increased recently in parallel to prolonged survival of patients with chronical infections, common use of the broad-spectrum antibiotics and cytotoxic drugs and surgical interventions. Fungi such as Trichosporon, Fusarium and Geotrichum that were previously evaluated as contaminant/colonization, become important causes of morbidity and mortality especially in neutropenic patients. The aim of this study was to investigate the presence of virulence factors such as acid proteinase, phospholipase, esterase, coagulase and hemolytic activity among Trichosporon species. A total of 40 Trichosporon strains, of them 24 (60%) were T.asahii, 6 (15%) were T.inkin and 10 (25%) were the other species (one of each of T.aquatile, T.asteroides, T.coremiiforme, T.cutaneum, T.dermatis, T.faecale, T.japonicum, T.montevideense, T.mucoides, T.ovoides) were included in the study. Identification of the isolates was performed according to microscopic morphology (blastospores, arthrospores, pseudohyphae and true hyphae) on corn meal agar media, and carbohydrate assimilation patterns (API ID32C; bioMérieux, France). Secretory acid proteinase, phospholipase and esterase activities of the strains were evaluated by 1% bovine serum albumin containing agar, by egg yolk containing solid medium, and by Tween 80 containing solid medium, respectively. Hemolytic activity of the isolates were evaluated by 5-10% sheep blood Sabouraud dextrose agar. Coagulase enzyme activity was determined by using human and rabbit plasma. In our study, all of the 40 Trichosporon spp. strains were found negative in terms of acid proteinase and phospholipase enzyme activity, however all were positive for esterase enzyme activity. Hemolytic enzyme activity were identified in a total of 15 (37.5%) strains, being "+++" in three strains (2 T.asahii, 1 T.japonicum), and "++" in 12 isolates (9 T.asahii, 1 T.inkin, 1 T.asteroides, 1 T.mentevideense). Although 11 of those 15 positive

  8. Virulence Factors Associated with Pediatric Shigellosis in Brazilian Amazon

    Directory of Open Access Journals (Sweden)

    Carolinie Batista Nobre da Cruz

    2014-01-01

    Full Text Available Shigellosis is a global human health problem and the incidence is highest among children. In the present work, main Shigella virulence genes was examined by PCR and compared to symptoms of pediatric shigellosis. Thirty Shigella isolates were identified from an etiologic study at which 1,339 children ranging 0–10 years old were enrolled. S. flexneri was the most frequent species reaching 60.0% of isolates, 22.2% were S. sonnei, and 6.6% were both S. dysenteriae and S. boydii. All Shigella infected children had diarrhea, but not all were accompanied by others symptoms of bacillary dysentery. Among major virulence genes, the PCR typing revealed ipaBCD was present in all isolates, followed by IpaH7.8, set-1A, set-1B, sen/ospD3, virF, and invE. The pathogenic potential of the ShET-1B subunit was observed in relation to dehydration (P<0.001 and ShET-2 related to the intestinal injury (P=0.033 evidenced by the presence of bloody diarrhea. Our results show associations among symptoms of shigellosis and virulence genes of clinical isolates of Shigella spp.

  9. Frequency distribution of virulence factors in uropathogenic Escherichia coli isolated from Kermanshah in 2011-2012.

    Science.gov (United States)

    Mohajeri, Parviz; Khademi, Hosna; Ebrahimi, Roya; Farahani, Abbas; Rezaei, Mansour

    2014-07-01

    Uropathogenic Escherichia coli (UPEC) can cause urinary tract infection (UTI). To prevent urine flow lavage, UPEC has acquired several virulence factors called adhesins. These adhesins are expressed and controlled by different genes. This study was aimed to determine some of the most important genes that control virulence factors of UPEC (pyelonephritis associated pili [pap], S fimbrial adhesion [sfa] and A fimbrial adhesion [afa] genes), which code for adhesins and phenotypic factors. In total, 205 UPEC isolates from in- and out-patients with UTI were obtained. Polymerase chain reaction was used for gene amplification. One drop of bacterial suspension, one of red blood cells and one of peripheral blood smear were mixed for hemagglutination (HA). Formation of a clump was considered to be positive. Bacteria were grown on blood agar to determine hemolysis. Surface hydrophobicity was determined using the SAT test. Frequencies of pap, afa and sfa were 42 (20.5%), 17 (8.3%) and 44 (21.5%), respectively. Frequencies of HA, hemolysis and hydrophobicity were 138 (67.3%), 56 (27.3%) and 39 (19%), respectively. Among HA-positive bacteria, 103 (74.6%) were mannose resistant. Our results highlight higher frequency of HA than that of other virulence factors, indicating a crucial role of this virulence factor in UPEC. We concluded that major differences exist in the prevalence of virulence factors among different UPEC isolated from different countries. The association observed between pathogenicity and virulence factors may promote UPEC survival and growth within the urinary tract. Detecting these genes as the primary controllers of UPEC virulence factors may aid in better management of related infections.

  10. Punicalagin Inhibits Salmonella Virulence Factors and Has Anti-Quorum-Sensing Potential

    OpenAIRE

    Li, Guanghui; Yan, Chunhong; Xu, Yunfeng; Feng, Yuqing; Wu, Qian; Lv, Xiaoying; Yang, Baowei; Wang, Xin; Xia, Xiaodong

    2014-01-01

    Punicalagin, an essential component of pomegranate rind, has been demonstrated to possess antimicrobial activity against several food-borne pathogens, but its activity on the virulence of pathogens and its anti-quorum-sensing (anti-QS) potential have been rarely reported. This study investigated the efficacy of subinhibitory concentrations of punicalagin on Salmonella virulence factors and QS systems. A broth microdilution method was used to determine the MICs of punicalagin for 10 Salmonella...

  11. Mitochondrial biogenesis in brown adipose tissue is associated with differential expression of transcription regulatory factors

    Czech Academy of Sciences Publication Activity Database

    Villena, J. A.; Carmona, M. C.; Rodriguez de la Concepción, M.; Rossmeisl, Martin; Vinas, O.; Mampel, T.; Iglesias, R.; Giralt, M.; Villarroya, F.

    2002-01-01

    Roč. 59, č. 11 (2002), s. 1934-1944 ISSN 1420-682X Grant - others:Ministerio de Ciencia y Tecnología(ES) PM98.0188 Institutional research plan: CEZ:AV0Z5011922 Keywords : brown adipose tissue * mitochondria * transcription factors Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 5.259, year: 2002

  12. Evaluation of phytochemicals from medicinal plants of Myrtaceae family on virulence factor production by Pseudomonas aeruginosa.

    Science.gov (United States)

    Musthafa, Khadar Syed; Sianglum, Wipawadee; Saising, Jongkon; Lethongkam, Sakkarin; Voravuthikunchai, Supayang Piyawan

    2017-05-01

    Virulence factors regulated by quorum sensing (QS) play a critical role in the pathogenesis of an opportunistic human pathogen, Pseudomonas aeruginosa in causing infections to the host. Hence, in the present work, the anti-virulence potential of the medicinal plant extracts and their derived phytochemicals from Myrtaceae family was evaluated against P. aeruginosa. In the preliminary screening of the tested medicinal plant extracts, Syzygium jambos and Syzygium antisepticum demonstrated a maximum inhibition in QS-dependent violacein pigment production by Chromobacterium violaceum DMST 21761. These extracts demonstrated an inhibitory activity over a virulence factor, pyoverdin, production by P. aeruginosa ATCC 27853. Gas chromatography-mass spectrometric (GC-MS) analysis revealed the presence of 23 and 12 phytochemicals from the extracts of S. jambos and S. antisepticum respectively. Three top-ranking phytochemicals, including phytol, ethyl linoleate and methyl linolenate, selected on the basis of docking score in molecular docking studies lowered virulence factors such as pyoverdin production, protease and haemolytic activities of P. aeruginosa to a significant level. In addition, the phytochemicals reduced rhamnolipid production by the organism. The work demonstrated an importance of plant-derived compounds as anti-virulence drugs to conquer P. aeruginosa virulence towards the host. © 2017 APMIS. Published by John Wiley & Sons Ltd.

  13. Identification of O-mannosylated Virulence Factors in Ustilago maydis

    Science.gov (United States)

    Fernández-Álvarez, Alfonso; Marín-Menguiano, Miriam; Lanver, Daniel; Jiménez-Martín, Alberto; Elías-Villalobos, Alberto; Pérez-Pulido, Antonio J.; Kahmann, Regine; Ibeas, José I.

    2012-01-01

    The O-mannosyltransferase Pmt4 has emerged as crucial for fungal virulence in the animal pathogens Candida albicans or Cryptococcus neoformans as well as in the phytopathogenic fungus Ustilago maydis. Pmt4 O-mannosylates specific target proteins at the Endoplasmic Reticulum. Therefore a deficient O-mannosylation of these target proteins must be responsible for the loss of pathogenicity in pmt4 mutants. Taking advantage of the characteristics described for Pmt4 substrates in Saccharomyces cerevisiae, we performed a proteome-wide bioinformatic approach to identify putative Pmt4 targets in the corn smut fungus U. maydis and validated Pmt4-mediated glycosylation of candidate proteins by electrophoretic mobility shift assays. We found that the signalling mucin Msb2, which regulates appressorium differentiation upstream of the pathogenicity-related MAP kinase cascade, is O-mannosylated by Pmt4. The epistatic relationship of pmt4 and msb2 showed that both are likely to act in the same pathway. Furthermore, constitutive activation of the MAP kinase cascade restored appressorium development in pmt4 mutants, suggesting that during the initial phase of infection the failure to O-mannosylate Msb2 is responsible for the virulence defect of pmt4 mutants. On the other hand we demonstrate that during later stages of pathogenic development Pmt4 affects virulence independently of Msb2, probably by modifying secreted effector proteins. Pit1, a protein required for fungal spreading inside the infected leaf, was also identified as a Pmt4 target. Thus, O-mannosylation of different target proteins affects various stages of pathogenic development in U. maydis. PMID:22416226

  14. Identification of O-mannosylated virulence factors in Ustilago maydis.

    Directory of Open Access Journals (Sweden)

    Alfonso Fernández-Álvarez

    Full Text Available The O-mannosyltransferase Pmt4 has emerged as crucial for fungal virulence in the animal pathogens Candida albicans or Cryptococcus neoformans as well as in the phytopathogenic fungus Ustilago maydis. Pmt4 O-mannosylates specific target proteins at the Endoplasmic Reticulum. Therefore a deficient O-mannosylation of these target proteins must be responsible for the loss of pathogenicity in pmt4 mutants. Taking advantage of the characteristics described for Pmt4 substrates in Saccharomyces cerevisiae, we performed a proteome-wide bioinformatic approach to identify putative Pmt4 targets in the corn smut fungus U. maydis and validated Pmt4-mediated glycosylation of candidate proteins by electrophoretic mobility shift assays. We found that the signalling mucin Msb2, which regulates appressorium differentiation upstream of the pathogenicity-related MAP kinase cascade, is O-mannosylated by Pmt4. The epistatic relationship of pmt4 and msb2 showed that both are likely to act in the same pathway. Furthermore, constitutive activation of the MAP kinase cascade restored appressorium development in pmt4 mutants, suggesting that during the initial phase of infection the failure to O-mannosylate Msb2 is responsible for the virulence defect of pmt4 mutants. On the other hand we demonstrate that during later stages of pathogenic development Pmt4 affects virulence independently of Msb2, probably by modifying secreted effector proteins. Pit1, a protein required for fungal spreading inside the infected leaf, was also identified as a Pmt4 target. Thus, O-mannosylation of different target proteins affects various stages of pathogenic development in U. maydis.

  15. How Do the Virulence Factors of Shigella Work Together to Cause Disease?

    Science.gov (United States)

    Mattock, Emily; Blocker, Ariel J

    2017-01-01

    Shigella is the major cause of bacillary dysentery world-wide. It is divided into four species, named S. flexneri, S. sonnei, S. dysenteriae, and S. boydii, which are distinct genomically and in their ability to cause disease. Shigellosis, the clinical presentation of Shigella infection, is characterized by watery diarrhea, abdominal cramps, and fever. Shigella's ability to cause disease has been attributed to virulence factors, which are encoded on chromosomal pathogenicity islands and the virulence plasmid. However, information on these virulence factors is not often brought together to create a detailed picture of infection, and how this translates into shigellosis symptoms. Firstly, Shigella secretes virulence factors that induce severe inflammation and mediate enterotoxic effects on the colon, producing the classic watery diarrhea seen early in infection. Secondly, Shigella injects virulence effectors into epithelial cells via its Type III Secretion System to subvert the host cell structure and function. This allows invasion of epithelial cells, establishing a replicative niche, and causes erratic destruction of the colonic epithelium. Thirdly, Shigella produces effectors to down-regulate inflammation and the innate immune response. This promotes infection and limits the adaptive immune response, causing the host to remain partially susceptible to re-infection. Combinations of these virulence factors may contribute to the different symptoms and infection capabilities of the diverse Shigella species, in addition to distinct transmission patterns. Further investigation of the dominant species causing disease, using whole-genome sequencing and genotyping, will allow comparison and identification of crucial virulence factors and may contribute to the production of a pan-Shigella vaccine.

  16. Virulence Factors Associated with Pediatric Shigellosis in Brazilian Amazon

    Science.gov (United States)

    da Cruz, Carolinie Batista Nobre; de Souza, Maria Carolina Scheffer; Serra, Paula Taquita; Santos, Ivanildes; Balieiro, Antonio; Pieri, Fabio Alessandro; Nogueira, Paulo Afonso; Orlandi, Patrícia Puccinelli

    2014-01-01

    Shigellosis is a global human health problem and the incidence is highest among children. In the present work, main Shigella virulence genes was examined by PCR and compared to symptoms of pediatric shigellosis. Thirty Shigella isolates were identified from an etiologic study at which 1,339 children ranging 0–10 years old were enrolled. S. flexneri was the most frequent species reaching 60.0% of isolates, 22.2% were S. sonnei, and 6.6% were both S. dysenteriae and S. boydii. All Shigella infected children had diarrhea, but not all were accompanied by others symptoms of bacillary dysentery. Among major virulence genes, the PCR typing revealed ipaBCD was present in all isolates, followed by IpaH7.8, set-1A, set-1B, sen/ospD3, virF, and invE. The pathogenic potential of the ShET-1B subunit was observed in relation to dehydration (P Shigella spp. PMID:24877110

  17. Characterization of putative virulence factors of Serratia marcescens strain SEN for pathogenesis in Spodoptera litura.

    Science.gov (United States)

    Aggarwal, Chetana; Paul, Sangeeta; Tripathi, Vishwas; Paul, Bishwajeet; Khan, Md Aslam

    2017-02-01

    Two Serratia marcescens strains, SEN and ICC-4, isolated from diseased insect cadavers were observed to differ considerably in their virulence towards Spodoptera litura. The present study was aimed to characterize the possible virulence factors present in the virulent Serratia marcescens strain SEN. Both the S. marcescens strains were evaluated for the presence of various lytic enzymes such as chitinase, lipase, protease and phospholipase. The virulent S. marcescens strain SEN was observed to possess considerably higher activity of chitinase and protease enzymes; activity of phospholipase enzyme was also higher. Although, all the three toxin genes shlA, phlA and swr could be detected in both the S. marcescens strains, there was a higher expression of these genes in the virulent strain SEN. S. marcescens strain ICC-4 showed greater reduction in overall growth yield in the post-exponential phase in the presence of midgut juice and hemolymph of S. litura larvae, as compared to S. marcescens strain SEN. Proliferation of the S. marcescens strain SEN was also considerably higher in foregut, midgut and hemolymph of S. litura larvae, as compared to strain ICC-4. Peritrophic membrane treated with broth culture of the S. marcescens strain SEN showed higher damage as compared to strain ICC-4. The peritrophic membrane of larvae fed on diet treated with the virulent strain showed considerable damage while the peritrophic membrane of larvae fed on diet treated with the non-virulent strain showed no damage. This is the first report documenting the fate of ingested S. marcescens in S. litura gut and the relative expression of toxin genes from two S. marcescens strains differing in their virulence towards S. litura. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. The ribosome biogenesis factor Nol11 is required for optimal rDNA transcription and craniofacial development in Xenopus.

    Directory of Open Access Journals (Sweden)

    John N Griffin

    2015-03-01

    Full Text Available The production of ribosomes is ubiquitous and fundamental to life. As such, it is surprising that defects in ribosome biogenesis underlie a growing number of symptomatically distinct inherited disorders, collectively called ribosomopathies. We previously determined that the nucleolar protein, NOL11, is essential for optimal pre-rRNA transcription and processing in human tissue culture cells. However, the role of NOL11 in the development of a multicellular organism remains unknown. Here, we reveal a critical function for NOL11 in vertebrate ribosome biogenesis and craniofacial development. Nol11 is strongly expressed in the developing cranial neural crest (CNC of both amphibians and mammals, and knockdown of Xenopus nol11 results in impaired pre-rRNA transcription and processing, increased apoptosis, and abnormal development of the craniofacial cartilages. Inhibition of p53 rescues this skeletal phenotype, but not the underlying ribosome biogenesis defect, demonstrating an evolutionarily conserved control mechanism through which ribosome-impaired craniofacial cells are removed. Excessive activation of this mechanism impairs craniofacial development. Together, our findings reveal a novel requirement for Nol11 in craniofacial development, present the first frog model of a ribosomopathy, and provide further insight into the clinically important relationship between specific ribosome biogenesis proteins and craniofacial cell survival.

  19. Hypoxia Reduces the Pathogenicity of Pseudomonas aeruginosa by Decreasing the Expression of Multiple Virulence Factors.

    Science.gov (United States)

    Schaible, Bettina; Rodriguez, Javier; Garcia, Amaya; von Kriegsheim, Alexander; McClean, Siobhán; Hickey, Caitríona; Keogh, Ciara E; Brown, Eric; Schaffer, Kirsten; Broquet, Alexis; Taylor, Cormac T

    2017-05-01

    Our understanding of how the course of opportunistic bacterial infection is influenced by the microenvironment is limited. We demonstrate that the pathogenicity of Pseudomonas aeruginosa strains derived from acute clinical infections is higher than that of strains derived from chronic infections, where tissues are hypoxic. Exposure to hypoxia attenuated the pathogenicity of strains from acute (but not chronic) infections, implicating a role for hypoxia in regulating bacterial virulence. Mass spectrometric analysis of the secretome of P. aeruginosa derived from an acute infection revealed hypoxia-induced repression of multiple virulence factors independent of altered bacterial growth. Pseudomonas aeruginosa lacking the Pseudomonas prolyl-hydroxylase domain-containing protein, which has been implicated in bacterial oxygen sensing, displays reduced virulence factor expression. Furthermore, pharmacological hydroxylase inhibition reduces virulence factor expression and pathogenicity in a murine model of pneumonia. We hypothesize that hypoxia reduces P. aeruginosa virulence at least in part through the regulation of bacterial hydroxylases. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

  20. Stationary phase-specific virulence factor overproduction by a lasR mutant of Pseudomonas aeruginosa.

    Directory of Open Access Journals (Sweden)

    Matthew T Cabeen

    Full Text Available Secreted virulence factors of the human pathogen Pseudomonas aeruginosa are often under quorum sensing control. Cells lacking the quorum-sensing regulator LasR show reduced virulence factor production under typical laboratory conditions and are hypo-virulent in short-term animal infection models, yet lasR mutants are frequently associated with long-term infection in cystic fibrosis patients. Here, I show that in stationary-phase or slow-growth conditions, lasR cells continuously and strongly produce the important virulence factor pyocyanin while wild-type cells do not. Pyocyanin overproduction by lasR cells is permitted by loss of repression by RsaL, a LasR-dependent negative regulator. lasR cells also contribute pyocyanin in mixed cultures, even under "cheating" conditions where they depend on their wild-type neighbors for nutrients. Finally, some clinical P. aeruginosa isolates with lasR mutations can overproduce pyocyanin in the laboratory. These results imply that slow-growing clinical populations of lasR cells in chronic infections may contribute to virulence by producing pyocyanin under conditions where lasR⁺ cells do not.

  1. Stationary Phase-Specific Virulence Factor Overproduction by a lasR Mutant of Pseudomonas aeruginosa

    Science.gov (United States)

    Cabeen, Matthew T.

    2014-01-01

    Secreted virulence factors of the human pathogen Pseudomonas aeruginosa are often under quorum sensing control. Cells lacking the quorum-sensing regulator LasR show reduced virulence factor production under typical laboratory conditions and are hypo-virulent in short-term animal infection models, yet lasR mutants are frequently associated with long-term infection in cystic fibrosis patients. Here, I show that in stationary-phase or slow-growth conditions, lasR cells continuously and strongly produce the important virulence factor pyocyanin while wild-type cells do not. Pyocyanin overproduction by lasR cells is permitted by loss of repression by RsaL, a LasR-dependent negative regulator. lasR cells also contribute pyocyanin in mixed cultures, even under “cheating” conditions where they depend on their wild-type neighbors for nutrients. Finally, some clinical P. aeruginosa isolates with lasR mutations can overproduce pyocyanin in the laboratory. These results imply that slow-growing clinical populations of lasR cells in chronic infections may contribute to virulence by producing pyocyanin under conditions where lasR+ cells do not. PMID:24533146

  2. Effect of Negative Pressure on Proliferation, Virulence Factor Secretion, Biofilm Formation, and Virulence-Regulated Gene Expression of Pseudomonas aeruginosa In Vitro

    Directory of Open Access Journals (Sweden)

    Guo-Qi Wang

    2016-01-01

    Full Text Available Objective. To investigate the effect of negative pressure conditions induced by NPWT on P. aeruginosa. Methods. P. aeruginosa was cultured in a Luria–Bertani medium at negative pressure of −125 mmHg for 24 h in the experimental group and at atmospheric pressure in the control group. The diameters of the colonies of P. aeruginosa were measured after 24 h. ELISA kit, orcinol method, and elastin-Congo red assay were used to quantify the virulence factors. Biofilm formation was observed by staining with Alexa Fluor® 647 conjugate of concanavalin A (Con A. Virulence-regulated genes were determined by quantitative RT-PCR. Results. As compared with the control group, growth of P. aeruginosa was inhibited by negative pressure. The colony size under negative pressure was significantly smaller in the experimental group than that in the controls (p<0.01. Besides, reductions in the total amount of virulence factors were observed in the negative pressure group, including exotoxin A, rhamnolipid, and elastase. RT-PCR results revealed a significant inhibition in the expression level of virulence-regulated genes. Conclusion. Negative pressure could significantly inhibit the growth of P. aeruginosa. It led to a decrease in the virulence factor secretion, biofilm formation, and a reduction in the expression level of virulence-regulated genes.

  3. The red pigment prodigiosin is not an essential virulence factor in entomopathogenic Serratia marcescens.

    Science.gov (United States)

    Zhou, Wei; Li, JingHua; Chen, Jie; Liu, XiaoYuan; Xiang, TingTing; Zhang, Lin; Wan, YongJi

    2016-05-01

    Although pigments produced by pathogenic microbes are generally hypothesized as essential virulence factors, the role of red pigment prodigiosin in the pathogenesis of entomopathogenic Serratia marcescens is not clear. In this study, we analyzed the pathogenicity of different pigmented S. marcescens strains and their non-pigmented mutants in silkworms. Each pigmented strain and the corresponding non-pigmented mutants showed very similar LD50 value (statistically no difference), but caused very different symptom (color of the dead larva). Our results clearly indicated that the red pigment prodigiosin is not an essential virulence factor in entomopathogenic S. marcescens. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Virulence Factors of Enterococcus faecium and Enterococcus faecalis Strains Isolated from Humans and Pets

    OpenAIRE

    GÜLHAN, Timur; AKSAKAL, Abdulbaki; EKİN, İsmail Hakkı; SAVAŞAN, Serap; BOYNUKARA, Banur

    2006-01-01

    The virulence factors of 146 Enterococcus faecium and 32 Enterococcus faecalis strains isolated from faecal samples of humans, dogs, and cats were investigated. In total, 178 strains were examined by gelatinase (GelE), aggregation substance (AS), cytolysin, and slide haemagglutination tests. The results of detected virulence factors of E. faecium and E. faecalis strains were: GelE: 17.1% vs. 37.5%; AS: 13% vs. 12.5%; cytolysin: 7.5% vs. 12.5%; haemagglutination activities with rabbit erythroc...

  5. Frequency of virulence factors in Helicobacter pylori-infected patients with gastritis.

    Science.gov (United States)

    Salimzadeh, Loghman; Bagheri, Nader; Zamanzad, Behnam; Azadegan-Dehkordi, Fatemeh; Rahimian, Ghorbanali; Hashemzadeh-Chaleshtori, Morteza; Rafieian-Kopaei, Mahmoud; Sanei, Mohammad Hossein; Shirzad, Hedayatollah

    2015-03-01

    The outcome of Helicobacter pylori infection has been related to specific virulence-associated bacterial genotypes. The vacuolating cytotoxin (vacA), cagA gene, oipA and babA2 gene are important virulence factor involving gastric diseases. The objective of this study was to assess the relationship between virulence factors of H. pylori and histopathological findings. Gastroduodenoscopy was performed in 436 dyspeptic patients. Antrum biopsy was obtained for detection of H. pylori, virulence factors and for histopathological assessment. The polymerase chain reaction was used to detect virulence factors of H. pylori using specific primers. vacA genotypes in patients infected with H. pylori were associated with cagA, iceA1 and iceA2. In the patients with H. pylori infection there was a significant relationship between cagA positivity and neutrophil activity (P = 0.004) and chronic inflammation (P = 0.013) and with H. pylori density (P = 0.034). Neutrophil infiltration was found to be more severe in the s1 group than in the s2 group (P = 0.042). Also was a significant relationship between oipA positivity and neutrophil activity (P = 0.004) and with H. pylori density (P = 0.018). No significant relationships were observed between other vacA genotypes and histopathological parameters. H. pylori strains showing cagA, vacA s1 and oipA positivity are associated with more severe gastritis in some histological features but virulence factors of H. pylori do not appear to determine the overall pattern of gastritis. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. [Antibiotic resistance and virulence factors in clinical Salmonella enterica isolates].

    Science.gov (United States)

    de Toro, María; Seral, Cristina; Rojo-Bezares, Beatriz; Torres, Carmen; Castillo, F Javier; Sáenz, Yolanda

    2014-01-01

    The increase of Salmonella enterica isolates multi-resistant to different antibiotics, including β-lactams and fluoroquinolones, is a problem of clinical importance. The dissemination of Salmonella Typhimurium resistant to ampicillin (AMP)-chloramphenicol (CHL)-streptomycin (STR)-sulphonamides and (SUL)-tetracycline (TET), that harbour the Salmonella Genomic Island type 1 (SGI1), and the acquisition of transferable genetic material have favoured the multi-resistance in this genus. A total of 114 clinical S.enterica isolates were studied (period 2009-2010). The susceptibility to 20 antibiotics was determined by disc diffusion and microdilution. The antimicrobial resistance mechanisms and the integrons were analysed by PCR, and sequencing in the AMP(R) isolates. In all the blaPSE-1-positive isolates, the clonal relationship was determined by PFGE, as well as the presence of SGI1 and 29 virulence genes by PCR. Eighteen different serotypes were found among the 114 isolates studied, Typhimurium (61%) and Enteritidis (16%) being the most prevalent. High percentages of resistance to SUL (68%), TET (58%), AMP (55%) and STR (46%) were observed. The great majority (92%) of 63 AMP(R) isolates were multi-resistant, with the AMP-STR-TET-SUL phenotype (19 isolates) being the most frequent one and associated with the blaTEM-1b+strA-strB+tet(B)+sul2 genotype. Class 1 integrons (7 different structures) were observed in 48% AMP(R) isolates, highlighting the blaOXA-1+aadA1 structure (8 isolates), one empty integron and non-classical integrons (5 isolates). The blaPSE-1 gene was detected inside the classical SGI1 structure in 13 clonally-related isolates that showed the same virulence profile. The high percentage of multi-resistant S.enterica isolates, especially associated to S.Typhimurium, to the AMP, STR, TET and SUL phenotype, and to the blaTEM-1b+strA-strB+tet(B)+sul2 genotype, shows an important risk of possible failures in the treatment of serious infections caused by this

  7. Catheter-related infections caused by Pseudomonas aeruginosa: virulence factors involved and their relationships.

    Science.gov (United States)

    Olejnickova, Katerina; Hola, Veronika; Ruzicka, Filip

    2014-11-01

    The nosocomial pathogen Pseudomonas aeruginosa is equipped with a large arsenal of cell-associated and secreted virulence factors which enhance its invasive potential. The complex relationships among virulence determinants have hitherto not been fully elucidated. In the present study, 175 catheter-related isolates were observed for the presence of selected virulence factors, namely extracellular enzymes and siderophore production, biofilm formation, resistance to antibiotics, and motility. A high percentage of the strains produced most of the tested virulence factors. A positive correlation was identified between the production of several exoproducts, and also between the formation of both types of biofilm. An opposite trend was observed between the two types of biofilm and the production of siderophores. Whereas the relationship between the submerged biofilm production (i.e. the biofilm formed on the solid surface below the water level) and the siderophore secretion was negative, the production of air-liquid interface (A-L) biofilm (i.e. the biofilm floating on the surface of the cultivation medium) and the siderophore secretion were positively correlated. All correlations were statistically significant at the level P = 0.05 with the correlation coefficient γ ≥ 0.50. Our results suggest that: (1) the co-production of the lytic enzymes and siderophores can play an important role in the pathogenesis of the catheter-related infections and should be taken into account when the virulence potential is assessed; (2) biofilm-positive strains are capable of forming both submerged and non-attached A-L biofilms; and (3) the different micro-environment in the submerged biofilm and A-L biofilm layers have opposite consequences for the production of other virulence factors. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  8. Effect of photodynamic therapy on the virulence factors of Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Maria eBartolomeu

    2016-03-01

    Full Text Available Staphylococcus aureus is a gram-positive bacterium who integrates the human microbiota. Nevertheless, these bacteria can be pathogenic to the humans. Due to the increasing occurrence of antibiotic-resistant S. aureus strains, new approaches to control this pathogen are necessary. The antimicrobial photodynamic inactivation (PDI process is based in the combined use of light, oxygen and an intermediary agent (a photosensitizer. These three components interact to generate cytotoxic reactive oxygen species that irreversibly damage vital constituents of the microbial cells and ultimately lead to cell death. Although PDI is being shown to be a promising alternative to the antibiotic approach for the inactivation of pathogenic microorganisms, information on effects of photosensitization on particular virulence factors is strikingly scarce. The objective of this work was to evaluate the effect of PDI on virulence factors of S. aureus and to assess the potential development of resistance of this bacterium as well as the recovery of the expression of the virulence factors after successive PDI cycles. For this, the photosensitizer 5,10,15,20-tetrakis(1-methylpyridinium-4-ylporphyrin tetra-iodide (Tetra-Py+-Me and six strains of S. aureus (one reference strain, one strain with 1 enterotoxin, two strains with 3 enterotoxins and two strains methicillin resistant (MRSA – one with 5 enterotoxins and the other without enterotoxins were used. The effect of photosensitization on catalase activity, beta hemolysis, lipases, thermonuclease, enterotoxins, coagulase production and resistance/susceptibility to methicillin was tested. To assess the development of resistance after successive cycles of treatment, three strains of S. aureus (ATCC 6538, 2065 MA and SA 3 MRSA were used. The surviving colonies of a first cycle of PDI were collected from the solid medium and subjected to further nine consecutive cycles of PDI. The results indicate that the expression of some

  9. Ecto-5'-nucleotidase: a candidate virulence factor in Streptococcus sanguinis experimental endocarditis.

    Directory of Open Access Journals (Sweden)

    Jingyuan Fan

    Full Text Available Streptococcus sanguinis is the most common cause of infective endocarditis (IE. Since the molecular basis of virulence of this oral commensal bacterium remains unclear, we searched the genome of S. sanguinis for previously unidentified virulence factors. We identified a cell surface ecto-5'-nucleotidase (Nt5e, as a candidate virulence factor. By colorimetric phosphate assay, we showed that S. sanguinis Nt5e can hydrolyze extracellular adenosine triphosphate to generate adenosine. Moreover, a nt5e deletion mutant showed significantly shorter lag time (P<0.05 to onset of platelet aggregation than the wild-type strain, without affecting platelet-bacterial adhesion in vitro (P=0.98. In the absence of nt5e, S. sanguinis caused IE (4 d in a rabbit model with significantly decreased mass of vegetations (P<0.01 and recovered bacterial loads (log(10CFU, P=0.01, suggesting that Nt5e contributes to the virulence of S. sanguinis in vivo. As a virulence factor, Nt5e may function by (i hydrolyzing ATP, a pro-inflammatory molecule, and generating adenosine, an immunosuppressive molecule to inhibit phagocytic monocytes/macrophages associated with valvular vegetations. (ii Nt5e-mediated inhibition of platelet aggregation could also delay presentation of platelet microbicidal proteins to infecting bacteria on heart valves. Both plausible Nt5e-dependent mechanisms would promote survival of infecting S. sanguinis. In conclusion, we now show for the first time that streptococcal Nt5e modulates S. sanguinis-induced platelet aggregation and may contribute to the virulence of streptococci in experimental IE.

  10. Detection of alpha-toxin and other virulence factors in biofilms of staphylococcus aureus on polystyrene and a human epidermalmodel

    NARCIS (Netherlands)

    P.M. den Reijer (Martijn); J.A. Haisma (Janneke); N. Lemmens-den Toom (Nicole); J. Willemse (José); R.A. Koning; J.A.A. Demmers (Jeroen); D.H. Dekkers (Dick); E.J. Rijkers; A. El Ghalbzouri (Abdoelwaheb); P.H. Nibbering (Peter); W.J.B. van Wamel (Willem)

    2016-01-01

    textabstractBackground & Aim: The ability of Staphylococcus aureus to successfully colonize (a)biotic surfaces may be explained by biofilm formation and the actions of virulence factors. The aim of the present study was to establish the presence of 52 proteins, including virulence factors such as

  11. Identification of novel secreted virulence factors from Xylella fastidiosa using a TRV expression system

    Science.gov (United States)

    Xylella fastidiosa is a bacterium that causes leaf scorch diseases of agriculturally important crops including grapevines and almonds. Little is known about virulence factors that are necessary for X. fastidiosa to grow and cause disease in the xylem vessels of a plant host. Any protein secreted by ...

  12. Study of Some Virulence Factors of E. Coli from Diarrheic Sheep ...

    African Journals Online (AJOL)

    The aim of this was study was to investigate some virulence factors of E. coli from diarrheic sheep and goats. E. coli was isolated at highest percentage from diarrheic sheep at age ranging from 1 to 6 months and highest percentage from diarrheic goats aged from 7 to 12 month. E. coli isolated from diarrheic sheep gave ...

  13. Dynamics of E.coli virulence factors in dairy cow herds

    Science.gov (United States)

    Background. Dairy farms are known reservoirs of entero-pathogenic E. coli (EPEC). EPEC, or the virulence factors associated with pathogenicity, have been detected in manure, milk, and the farm environment. However, it is unclear which farm compartments are reservoirs contributing to EPEC persistence...

  14. Molecular characterization of Candida in the oral cavity and factors involved in biofilm formation and virulence

    NARCIS (Netherlands)

    Kraneveld, E.A.

    2014-01-01

    The research described in this thesis addresses current issues related to oral Candida infections. Interactions of Candida with the oral microbiome were characterized and factors involved in biofilm formation and virulence were studied. All in all, the work described in this thesis contributes

  15. Hemolysin as a Virulence Factor for Systemic Infection with Isolates of Mycobacterium avium Complex

    Science.gov (United States)

    Maslow, Joel N.; Dawson, David; Carlin, Elizabeth A.; Holland, Steven M.

    1999-01-01

    Isolates of the Mycobacterium avium complex were examined for hemolysin expression. Only invasive isolates of M. avium were observed to be hemolytic (P < 0.001), with activity the greatest for isolates of serovars 4 and 8. Thus, M. avium hemolysin appears to represent a virulence factor necessary for invasive disease. PMID:9889239

  16. 53 review article a review of the virulence factors of pathogenic fungi

    African Journals Online (AJOL)

    boaz

    Melanin is produced by a number of pathogenic fungi, and protects against harsh conditions such as UV radiation, increased temperature and ROS. The ability to obtain Iron (Fe) from the storage or transport forms in the host is also a virulence factor and calcineurin acts as a sensor for pathogenic fungi. Key words: Fungi ...

  17. A review of the virulence factors of pathogenic fungi | Iyalla | African ...

    African Journals Online (AJOL)

    Melanin is produced by a number of pathogenic fungi, and protects against harsh conditions such as UV radiation, increased temperature and ROS. The ability to obtain Iron (Fe) from the storage or transport forms in the host is also a virulence factor and calcineurin acts as a sensor for pathogenic fungi. Keywords: Fungi ...

  18. Staphylococcus aureus clonal dynamics and virulence factors in children with atopic dermatitis

    DEFF Research Database (Denmark)

    Lomholt, Hans; Andersen, Klaus Ejner; Kilian, Mogens

    2005-01-01

    , toxins, and were assigned to agr groups. S. aureus colonization patterns ranged from rare colonization over transient colonization to persistent colonization by a single clone or a dynamic exchange of up to five clones. Production of no single virulence factor including superantigens and toxins...

  19. Molecular detection of virulence factors among food and clinical Enterococcus faecalis strains in South Brazil

    Directory of Open Access Journals (Sweden)

    A.W. Medeiros

    2014-01-01

    Full Text Available The present report aimed to perform a molecular epidemiological survey by investigating the presence of virulence factors in E. faecalis isolated from different human clinical (n = 57 and food samples (n = 55 in Porto Alegre, Brazil, collected from 2006 to 2009. In addition, the ability to form biofilm in vitro on polystyrene and the β-haemolytic and gelatinase activities were determined. Clinical strains presented a higher prevalence of aggregation substance (agg, enterococcal surface protein (esp and cytolysin (cylA genes when compared with food isolates. The esp gene was found only in clinical strains. On the other hand, the gelatinase (gelE and adherence factor (ace genes had similar prevalence among the strains, showing the widespread occurrence of these virulence factors among food and clinical E. faecalis strains in South Brazil. More than three virulence factor genes were detected in 77.2% and 18.2% of clinical and food strains, respectively. Gelatinase and β-haemolysin activities were not associated with the presence of gelE and cylA genes. The ability to produce biofilm was detected in 100% of clinical and 94.6% of food isolates, and clinical strains were more able to form biofilm than the food isolates (Student's t-test, p < 0.01. Results from the statistical analysis showed significant associations between strong biofilm formation and ace (p = 0.015 and gelE (p = 0.007 genes in clinical strains. In conclusion, our data indicate that E. faecalis strains isolated from clinical and food samples possess distinctive patterns of virulence factors, with a larger number of genes that encode virulence factors detected in clinical strains.

  20. Novel Burkholderia mallei Virulence Factors Linked to Specific Host-Pathogen Protein Interactions*

    Science.gov (United States)

    Memišević, Vesna; Zavaljevski, Nela; Pieper, Rembert; Rajagopala, Seesandra V.; Kwon, Keehwan; Townsend, Katherine; Yu, Chenggang; Yu, Xueping; DeShazer, David; Reifman, Jaques; Wallqvist, Anders

    2013-01-01

    Burkholderia mallei is an infectious intracellular pathogen whose virulence and resistance to antibiotics makes it a potential bioterrorism agent. Given its genetic origin as a commensal soil organism, it is equipped with an extensive and varied set of adapted mechanisms to cope with and modulate host-cell environments. One essential virulence mechanism constitutes the specialized secretion systems that are designed to penetrate host-cell membranes and insert pathogen proteins directly into the host cell's cytosol. However, the secretion systems' proteins and, in particular, their host targets are largely uncharacterized. Here, we used a combined in silico, in vitro, and in vivo approach to identify B. mallei proteins required for pathogenicity. We used bioinformatics tools, including orthology detection and ab initio predictions of secretion system proteins, as well as published experimental Burkholderia data to initially select a small number of proteins as putative virulence factors. We then used yeast two-hybrid assays against normalized whole human and whole murine proteome libraries to detect and identify interactions among each of these bacterial proteins and host proteins. Analysis of such interactions provided both verification of known virulence factors and identification of three new putative virulence proteins. We successfully created insertion mutants for each of these three proteins using the virulent B. mallei ATCC 23344 strain. We exposed BALB/c mice to mutant strains and the wild-type strain in an aerosol challenge model using lethal B. mallei doses. In each set of experiments, mice exposed to mutant strains survived for the 21-day duration of the experiment, whereas mice exposed to the wild-type strain rapidly died. Given their in vivo role in pathogenicity, and based on the yeast two-hybrid interaction data, these results point to the importance of these pathogen proteins in modulating host ubiquitination pathways, phagosomal escape, and actin

  1. AhrC and Eep are biofilm infection-associated virulence factors in Enterococcus faecalis.

    Science.gov (United States)

    Frank, Kristi L; Guiton, Pascale S; Barnes, Aaron M T; Manias, Dawn A; Chuang-Smith, Olivia N; Kohler, Petra L; Spaulding, Adam R; Hultgren, Scott J; Schlievert, Patrick M; Dunny, Gary M

    2013-05-01

    Enterococcus faecalis is part of the human intestinal microbiome and is a prominent cause of health care-associated infections. The pathogenesis of many E. faecalis infections, including endocarditis and catheter-associated urinary tract infection (CAUTI), is related to the ability of clinical isolates to form biofilms. To identify chromosomal genetic determinants responsible for E. faecalis biofilm-mediated infection, we used a rabbit model of endocarditis to test strains with transposon insertions or in-frame deletions in biofilm-associated loci: ahrC, argR, atlA, opuBC, pyrC, recN, and sepF. Only the ahrC mutant was significantly attenuated in endocarditis. We demonstrate that the transcriptional regulator AhrC and the protease Eep, which we showed previously to be an endocarditis virulence factor, are also required for full virulence in murine CAUTI. Therefore, AhrC and Eep can be classified as enterococcal biofilm-associated virulence factors. Loss of ahrC caused defects in early attachment and accumulation of biofilm biomass. Characterization of ahrC transcription revealed that the temporal expression of this locus observed in wild-type cells promotes initiation of early biofilm formation and the establishment of endocarditis. This is the first report of AhrC serving as a virulence factor in any bacterial species.

  2. Genome-wide screen of Pseudomonas aeruginosa In Saccharomyces cerevisiae identifies new virulence factors

    Directory of Open Access Journals (Sweden)

    Rafat eZrieq

    2015-11-01

    Full Text Available Pseudomonas aeruginosa is a human opportunistic pathogen that causes mortality in cystic fibrosis and immunocompromised patients. While many virulence factors of this pathogen have already been identified, several remain to be discovered. In this respect we set an unprecedented genome-wide screen of a P. aeruginosa expression library based on a yeast growth phenotype. 51 candidates were selected in a three-round screening process. The robustness of the screen was validated by the selection of three well known secreted proteins including one demonstrated virulence factor, the protease LepA. Further in silico sorting of the 51 candidates highlighted three potential new Pseudomonas effector candidates (Pec. By testing the cytotoxicity of wild type P. aeruginosa vs pec mutants towards macrophages and the virulence in the Caenorhabditis elegans model, we demonstrated that the three selected Pecs are novel virulence factors of P. aeruginosa. Additional cellular localization experiments in the host revealed specific localization for Pec1 and Pec2 that could inform about their respective functions.

  3. Presence of virulence factors in Enterococcus faecalis and Enterococcus faecium susceptible and resistant to vancomycin

    Directory of Open Access Journals (Sweden)

    Carolina Baldisserotto Comerlato

    2013-08-01

    Full Text Available Despite the increasing importance of Enterococcus as opportunistic pathogens, their virulence factors are still poorly understood. This study determines the frequency of virulence factors in clinical and commensal Enterococcus isolates from inpatients in Porto Alegre, Brazil. Fifty Enterococcus isolates were analysed and the presence of the gelE, asa1 and esp genes was determined. Gelatinase activity and biofilm formation were also tested. The clonal relationships among the isolates were evaluated using pulsed-field gel electrophoresis. The asa1, gelE and esp genes were identified in 38%, 60% and 76% of all isolates, respectively. The first two genes were more prevalent in Enterococcus faecalis than in Enterococcus faecium, as was biofilm formation, which was associated with gelE and asa1 genes, but not with the esp gene. The presence of gelE and the activity of gelatinase were not fully concordant. No relationship was observed among any virulence factors and specific subclones of E. faecalis or E. faecium resistant to vancomycin. In conclusion, E. faecalis and E. faecium isolates showed significantly different patterns of virulence determinants. Neither the source of isolation nor the clonal relationship or vancomycin resistance influenced their distribution.

  4. Effect of subinhibitory concentrations of chlorogenic acid on reducing the virulence factor production by Staphylococcus aureus.

    Science.gov (United States)

    Li, Guanghui; Qiao, Mingyu; Guo, Yan; Wang, Xin; Xu, Yunfeng; Xia, Xiaodong

    2014-09-01

    Chlorogenic acid (CA) has been reported to inhibit several pathogens, but the influence of subinhibitory concentrations of CA on virulence expression of pathogens has not been fully elucidated. The aim of this study was to explore the effect of CA on the virulence factor production of Staphylococcus aureus. The minimum inhibitory concentration (MIC) of CA against S. aureus was determined using a broth microdilution method. Hemolysin assays, coagulase titer assays, adherence to solid-phase fibrinogen assays, Western blot, and real-time reverse transcriptase-polymerase chain reaction were performed to evaluate the effect of subinhibitory concentrations of CA on the virulence factors of S. aureus. MIC of CA against S. aureus ATCC29213 was found to be 2.56 mg/mL. At subinhibitory concentrations, CA significantly inhibited the hemolysis and dose-dependently decreased coagulase titer. Reduced binding to fibrinogen and decreased production of SEA were observed with treatment of CA at concentrations ranging from 1/16MIC to 1/2MIC. CA markedly inhibited the expression of hla, sea, and agr genes in S. aureus. These data demonstrate that the virulence expression of S. aureus could be reduced by CA and suggest that CA could be potentially developed as a supplemental strategy to control S. aureus infection and to prevent staphylococcal food poisoning.

  5. Sequence Analysis of Hypothetical Proteins from 26695 to Identify Potential Virulence Factors

    Directory of Open Access Journals (Sweden)

    Ahmad Abu Turab Naqvi

    2016-09-01

    Full Text Available Helicobacter pylori is a Gram-negative bacteria that is responsible for gastritis in human. Its spiral flagellated body helps in locomotion and colonization in the host environment. It is capable of living in the highly acidic environment of the stomach with the help of acid adaptive genes. The genome of H. pylori 26695 strain contains 1,555 coding genes that encode 1,445 proteins. Out of these, 340 proteins are characterized as hypothetical proteins (HP. This study involves extensive analysis of the HPs using an established pipeline which comprises various bioinformatics tools and databases to find out probable functions of the HPs and identification of virulence factors. After extensive analysis of all the 340 HPs, we found that 104 HPs are showing characteristic similarities with the proteins with known functions. Thus, on the basis of such similarities, we assigned probable functions to 104 HPs with high confidence and precision. All the predicted HPs contain representative members of diverse functional classes of proteins such as enzymes, transporters, binding proteins, regulatory proteins, proteins involved in cellular processes and other proteins with miscellaneous functions. Therefore, we classified 104 HPs into aforementioned functional groups. During the virulence factors analysis of the HPs, we found 11 HPs are showing significant virulence. The identification of virulence proteins with the help their predicted functions may pave the way for drug target estimation and development of effective drug to counter the activity of that protein.

  6. Characterization of virulence factors and clonal diversity of Enterococcus faecalis isolates from treated dental root canals.

    Science.gov (United States)

    Zoletti, Gustavo O; Pereira, Eliezer M; Schuenck, Ricardo P; Teixeira, Lúcia M; Siqueira, José F; dos Santos, Kátia Regina N

    2011-01-01

    The high prevalence of Enterococcus faecalis in root canal treated teeth with post-treatment disease, as evidenced by both molecular and traditional culturing methods, suggests that this species may be a key player in endodontic treatment failure. This study aimed to detect virulence factors by phenotypic and western blotting tests, and virulence genes by PCR from 20 clinical strains of E. faecalis isolated from treated root canals of teeth with (10) or without (10) apical periodontitis. Moreover, genomic diversity of these strains was assessed by pulsed-field gel electrophoresis (PFGE) and rep-PCR. All 20 strains presented the gelE gene (gelatinase), but 10 of them did not hydrolyze gelatin. Seven of the 10 gelatinase-producing isolates were recovered from root canals with lesions, which suggests a role for this virulence factor in the pathogenesis of post-treatment disease. The esp gene was expressed only in cases where gelatinase production was negative. The other virulence genes were found in 90% (efaA and ace genes), 45% (agg gene) and 95% (cpd gene) of the E. faecalis isolates. As for PFGE and rep-PCR, no specific clonal type of E. faecalis was found in association with teeth with or without disease, revealing the interindividual clonal diversity of endodontic infections. Copyright © 2010 Institut Pasteur. Published by Elsevier SAS. All rights reserved.

  7. The Clinical Correlations of Helicobacter pylori Virulence Factors and Chronic Spontaneous Urticaria

    Directory of Open Access Journals (Sweden)

    Yi-Chun Chiu

    2013-01-01

    Full Text Available Background and Study Aims. The association between Helicobacter pylori (H. pylori and chronic spontaneous urticaria (CSU remains controversial. This study explored the role of H. pylori in CSU among different virulent genotypes patients. Patients and Methods. Patients infected by H. pylori were sorted into two groups as group A (with CSU and group B (without CSU. The tissue materials were taken via endoscopy for polymerase chain reaction study to determine virulence factors. After H. pylori eradication therapy, the eradication rate and response of urticaria were evaluated by using C13-UBT and a three-point scale (complete remission, partial remission, or no improvement. Results. The results were comparable between patients of groups A and B in terms of H. pylori infection rates and eradication rate. Longitudinal follow-up of 23.5 months showed complete remission of urticaria in 63.6% but no improvement in 36.4% of the patients after H. pylori eradication. H. pylori infected patients with different virulence factors such as cytotoxin-associated gene A, vacuolating cytotoxin gene A signal region and middle region have similar remission rates for CSU. Conclusions. Current study suggests that H. pylori may play a role in the development and disease course of CSU but may be irrelevant to different virulent genotypes.

  8. Chemical Inhibition of Kynureninase Reduces Pseudomonas aeruginosa Quorum Sensing and Virulence Factor Expression.

    Science.gov (United States)

    Kasper, Stephen H; Bonocora, Richard P; Wade, Joseph T; Musah, Rabi Ann; Cady, Nathaniel C

    2016-04-15

    The opportunistic pathogen Pseudomonas aeruginosa utilizes multiple quorum sensing (QS) pathways to coordinate an arsenal of virulence factors. We previously identified several cysteine-based compounds inspired by natural products from the plant Petiveria alliacea which are capable of antagonizing multiple QS circuits as well as reducing P. aeruginosa biofilm formation. To understand the global effects of such compounds on virulence factor production and elucidate their mechanism of action, RNA-seq transcriptomic analysis was performed on P. aeruginosa PAO1 exposed to S-phenyl-l-cysteine sulfoxide, the most potent inhibitor from the prior study. Exposure to this inhibitor down-regulated expression of several QS-regulated virulence operons (e.g., phenazine biosynthesis, type VI secretion systems). Interestingly, many genes that were differentially regulated pertain to the related metabolic pathways that yield precursors of pyochelin, tricarboxylic acid cycle intermediates, phenazines, and Pseudomonas quinolone signal (PQS). Activation of the MexT-regulon was also indicated, including the multidrug efflux pump encoded by mexEF-oprN, which has previously been shown to inhibit QS and pathogenicity. Deeper investigation of the metabolites involved in these systems revealed that S-phenyl-l-cysteine sulfoxide has structural similarity to kynurenine, a precursor of anthranilate, which is critical for P. aeruginosa virulence. By supplementing exogenous anthranilate, the QS-inhibitory effect was reversed. Finally, it was shown that S-phenyl-l-cysteine sulfoxide competitively inhibits P. aeruginosa kynureninase (KynU) activity in vitro and reduces PQS production in vivo. The kynurenine pathway has been implicated in P. aeruginosa QS and virulence factor expression; however, this is the first study to show that targeted inhibition of KynU affects P. aeruginosa gene expression and QS, suggesting a potential antivirulence strategy.

  9. Biogenesis of Enterococcis faecium biofilms

    NARCIS (Netherlands)

    Paganelli, F.L.

    2015-01-01

    Nosocomial infections caused by Enterococcus faecium have rapidly increased worldwide and treatment options become more limited. The presence of antibiotic resistance genes and virulence factors in pathogenic E. faecium contribute to difficult-to-treat infections, frequently biofilm mediated, such

  10. Weapons of mass destruction: virulence factors of the global killer enterotoxigenic Escherichia coli.

    Science.gov (United States)

    Turner, Susan M; Scott-Tucker, Anthony; Cooper, Lisa M; Henderson, Ian R

    2006-10-01

    Enterotoxigenic Escherichia coli (ETEC) is the most common cause of food and water-borne E. coli-mediated human diarrhoea worldwide. The incidence in developing countries is estimated at 650 million cases per year, resulting in 800 000 deaths, primarily in children under the age of five. ETEC is also the most common cause of diarrhoea among travellers, including the military, from industrialized nations to less developed countries. In addition, ETEC is a major pathogen of animals, being responsible for scours in cattle and neonatal and postweaning diarrhoea in pigs and resulting in significant financial losses. Studies on the pathogenesis of ETEC infections have concentrated on the plasmid-encoded heat-stable and heat-labile enterotoxins and on the plasmid-encoded antigenically variable colonization factors. Relatively little work has been carried out on chromosomally encoded virulence factors. Here, we review the known virulence factors of ETEC and highlight the future for combating this major disease.

  11. Helicobacter pylori infection: An overview of bacterial virulence factors and pathogenesis

    Directory of Open Access Journals (Sweden)

    Cheng-Yen Kao

    2016-02-01

    Full Text Available Helicobacter pylori pathogenesis and disease outcomes are mediated by a complex interplay between bacterial virulence factors, host, and environmental factors. After H. pylori enters the host stomach, four steps are critical for bacteria to establish successful colonization, persistent infection, and disease pathogenesis: (1 Survival in the acidic stomach; (2 movement toward epithelium cells by flagella-mediated motility; (3 attachment to host cells by adhesins/receptors interaction; (4 causing tissue damage by toxin release. Over the past 20 years, the understanding of H. pylori pathogenesis has been improved by studies focusing on the host and bacterial factors through epidemiology researches and molecular mechanism investigations. These include studies identifying the roles of novel virulence factors and their association with different disease outcomes, especially the bacterial adhesins, cag pathogenicity island, and vacuolating cytotoxin. Recently, the development of large-scale screening methods, including proteomic, and transcriptomic tools, has been used to determine the complex gene regulatory networks in H. pylori. In addition, a more available complete genomic database of H. pylori strains isolated from patients with different gastrointestinal diseases worldwide is helpful to characterize this bacterium. This review highlights the key findings of H. pylori virulence factors reported over the past 20 years.

  12. Helicobacter pylori and Its Virulence Factors' Effect on Serum Oxidative DNA Damages in Adults With Dyspepsia

    Directory of Open Access Journals (Sweden)

    Heshmat Shahi

    2016-12-01

    Full Text Available Helicobacter Pylori infection is a common gastrointestinal infection that can cause pathological effects, increase oxidative stress and induce an inflammatory response in gastric mucosa. Inflammatory aspects may prompt the production of radical oxygen substance (ROS which may damage cells and release 8-hydroxydyoxyguanosine (8-OHdG to serum. In this study, we evaluate the prevalence of H. pylori virulence factors and the association between serum level of 8-OHdG, H. pylori infection, and its various virulence factors. The presence of H. pylori and prevalence of cagA, babA and oipA genes in samples were determined by rapid urease test (RUT, histopathological exam (HE and polymerase chain reaction (PCR and oxidative DNA damage situation were assessed by using serum level of 8-OHdG. There was not any direct relation between H. pylori negative and H. pylori oipA+specimens by 8-OHdG serum level (P>0.05. In all clinical observations, the presence of cagA and oipA genes was common. There was a statistical relationship between the presence of cagA, babA factors, and high serum level of 8-OHdG (P<0.05. The presence of cagA and babA virulence factors may be associated with increased serum 8-OHdG in dyspeptic patients and may induce the damage to gastric cells.

  13. Helicobacter pylori and Its Virulence Factors' Effect on Serum Oxidative DNA Damages in Adults With Dyspepsia.

    Science.gov (United States)

    Shahi, Heshmat; Bahreiny, Rasoul; Reiisi, Somayeh

    2016-11-01

    Helicobacter Pylori infection is a common gastrointestinal infection that can cause pathological effects, increase oxidative stress and induce an inflammatory response in gastric mucosa. Inflammatory aspects may prompt the production of radical oxygen substance (ROS) which may damage cells and release 8-hydroxydyoxyguanosine (8-OHdG) to serum. In this study, we evaluate the prevalence of H. pylori virulence factors and the association between serum level of 8-OHdG, H. pylori infection, and its various virulence factors. The presence of H. pylori and prevalence of cagA, babA and oipA genes in samples were determined by rapid urease test (RUT), histopathological exam (HE) and polymerase chain reaction (PCR) and oxidative DNA damage situation were assessed by using serum level of 8-OHdG. There was not any direct relation between H. pylori negative and H. pylori oipA+specimens by 8-OHdG serum level (P>0.05). In all clinical observations, the presence of cagA and oipA genes was common. There was a statistical relationship between the presence of cagA, babA factors, and high serum level of 8-OHdG (P<0.05). The presence of cagA and babA virulence factors may be associated with increased serum 8-OHdG in dyspeptic patients and may induce the damage to gastric cells.

  14. Arcanobacterium pyogenes: Virulence factors, importance in mastitis etiology and therapeutic (impossibilities

    Directory of Open Access Journals (Sweden)

    Milanov Dubravka

    2011-01-01

    Full Text Available Arcanobacterium pyogenes is an opportunistic pathogen, a causative agent of suppurative infections of organs and tissues in economically important livestock species. Most frequently this bacteria is isolated from inflamed lung lesions in pigs and cattle, in samples of uterine mucus of cows with endometritis and milk from cows with clinical mastitis. A. pyogenes possesses a number of virulence factors: cholesterol-dependent cytolysin (pyolysin, two neuraminidases, several proteases, extracellular matrix-binding proteins, DNases, fimbriae. The virulence factors are well studied in laboratory conditions, but the role of these factors in the pathogenesis of A. pyogenes infections remains to be elucidated. Lately, the ability of A. pyogenes to form biofilm in vivo has also been implicated as a virulence factor and a possible cause of therapeutic failure. Despite the fact that A. pyogenes milk isolates in cows with mastitis in vitro are very sensitive to β-lactam drugs and tetracycline, experience has shown that therapy is usually ineffective, prognosis is poor and the affected quarter is lost for milk production.

  15. The RNA-Binding Chaperone Hfq Is an Important Global Regulator of Gene Expression in Pasteurella multocida and Plays a Crucial Role in Production of a Number of Virulence Factors, Including Hyaluronic Acid Capsule

    National Research Council Canada - National Science Library

    Mégroz, Marianne; Kleifeld, Oded; Wright, Amy; Powell, David; Harrison, Paul; Adler, Ben; Harper, Marina; Boyce, John D

    2016-01-01

    .... multocida virulence factors have been identified, including capsule, lipopolysaccharide (LPS), and filamentous hemagglutinin, but little is known about how the expression of these virulence factors is regulated...

  16. Imaging mass spectrometry and genome mining reveal highly antifungal virulence factor of mushroom soft rot pathogen.

    Science.gov (United States)

    Graupner, Katharina; Scherlach, Kirstin; Bretschneider, Tom; Lackner, Gerald; Roth, Martin; Gross, Harald; Hertweck, Christian

    2012-12-21

    Caught in the act: imaging mass spectrometry of a button mushroom infected with the soft rot pathogen Janthinobacterium agaricidamnosum in conjunction with genome mining revealed jagaricin as a highly antifungal virulence factor that is not produced under standard cultivation conditions. The structure of jagaricin was rigorously elucidated by a combination of physicochemical analyses, chemical derivatization, and bioinformatics. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. ANTIBIOTICS RESISTANCE AND PUTATIVE VIRULENCE FACTORS OF AEROMONAS HYDROPHILA ISOLATED FROM ESTUARY

    OpenAIRE

    Olumide Adedokun Odeyemi; Ahmad Asmat; Gires Usup

    2012-01-01

    This study aim to investigate antibiotics resistance profile and putative virulence factors of Aeromonas hydrophila isolated from estuary. Bacteria used for this study were isolated from water and sediment samples obtained from Sungai Melayu, Johor, Malaysia. Serially diluted 100 µL water and 1g sediment were inoculated on modified Rimler - Shott (mRS) agar. Colonies with distinct cultural characteristics were picked for further studies. Isolates were tested for biofilm productions, protease ...

  18. Candida Species From Eye Infections: Drug Susceptibility, Virulence Factors, and Molecular Characterization.

    Science.gov (United States)

    Ranjith, Konduri; Sontam, Bhavani; Sharma, Savitri; Joseph, Joveeta; Chathoth, Kanchana N; Sama, Kalyana C; Murthy, Somasheila I; Shivaji, Sisinthy

    2017-08-01

    To determine the type of Candida species in ocular infections and to investigate the relationship of antifungal susceptibility profile to virulence factors. Fifty isolates of yeast-like fungi from patients with keratitis, endophthalmitis, and orbital cellulitis were identified by Vitek-2 compact system and DNA sequencing of ITS1-5.8S-ITS2 regions of the rRNA gene, followed by phylogenetic analysis for phenotypic and genotypic identification, respectively. Minimum inhibitory concentration of six antifungal drugs was determined by E test/microbroth dilution methods. Phenotypic and genotypic methods were used to determine the virulence factors. Phylogenetic analysis showed the clustering of all isolates into eight distinct groups with a major cluster formed Candida parapsilosis (n = 21), which was the most common species by both Vitek 2 and DNA sequencing. Using χ2 test no significant difference was noted between the techniques except that Vitek 2 did not identify C. viswanathii, C. orthopsilosis, and two non-Candida genera. Of 43 tested Candida isolates high susceptibility to amphotericin B (39/43, 90.6%) and natamycin (43/43, 100%) was noted. While none of the isolates produced coagulase, all produced esterase and catalase. The potential to form biofilm was detected in 23/43 (53.4%) isolates. Distribution of virulence factors by heat map analysis showed difference in metabolic activity of biofilm producers from nonbiofilm producers. Identified by Vitek 2 and DNA sequencing methods C. parapsilosis was the most common species associated with eye infections. Irrespective of the virulence factors elaborated, the Candida isolates were susceptible to commonly used antifungal drugs such as amphotericin B and natamycin.

  19. Cold Plasma Inactivation of Bacterial Biofilms and Reduction of Quorum Sensing Regulated Virulence Factors.

    Directory of Open Access Journals (Sweden)

    Dana Ziuzina

    Full Text Available The main objectives of this work were to investigate the effect of atmospheric cold plasma (ACP against a range of microbial biofilms commonly implicated in foodborne and healthcare associated human infections and against P. aeruginosa quorum sensing (QS-regulated virulence factors, such as pyocyanin, elastase (Las B and biofilm formation capacity post-ACP treatment. The effect of processing factors, namely treatment time and mode of plasma exposure on antimicrobial activity of ACP were also examined. Antibiofilm activity was assessed for E. coli, L. monocytogenes and S. aureus in terms of reduction of culturability and retention of metabolic activity using colony count and XTT assays, respectively. All samples were treated 'inpack' using sealed polypropylene containers with a high voltage dielectric barrier discharge ACP generated at 80 kV for 0, 60, 120 and 300 s and a post treatment storage time of 24 h. According to colony counts, ACP treatment for 60 s reduced populations of E. coli to undetectable levels, whereas 300 s was necessary to significantly reduce populations of L. monocytogenes and S. aureus biofilms. The results obtained from XTT assay indicated possible induction of viable but non culturable state of bacteria. With respect to P. aeruginosa QS-related virulence factors, the production of pyocyanin was significantly inhibited after short treatment times, but reduction of elastase was notable only after 300 s and no reduction in actual biofilm formation was achieved post-ACP treatment. Importantly, reduction of virulence factors was associated with reduction of the cytotoxic effects of the bacterial supernatant on CHO-K1 cells, regardless of mode and duration of treatment. The results of this study point to ACP technology as an effective strategy for inactivation of established biofilms and may play an important role in attenuation of virulence of pathogenic bacteria. Further investigation is warranted to propose direct evidence

  20. Distribution and dynamics of epidemic and pandemic Vibrio parahaemolyticus virulence factors

    Directory of Open Access Journals (Sweden)

    Daniela eCeccarelli

    2013-12-01

    Full Text Available Vibrio parahaemolyticus, autochthonous to estuarine, marine, and coastal environments throughout the world, is the causative agent of food-borne gastroenteritis. More than 80 serotypes have been described worldwide, based on antigenic properties of the somatic (O and capsular (K antigens. Serovar O3:K6 emerged in India in 1996 and subsequently was isolated worldwide, leading to the conclusion that the first V. parahaemolyticus pandemic had taken place. Most strains of V. parahaemolyticus isolated from the environment or seafood, in contrast to clinical strains, do not produce a thermostable direct hemolysin (TDH and/or a TDH-related hemolysin (TRH. Type 3 secretion systems (T3SSs, needle-like apparatuses able to deliver bacterial effectors into host cytoplasm, were identified as triggering cytotoxicity and enterotoxicity. Type 6 secretion systems (T6SS predicted to be involved in intracellular trafficking and vesicular transport appear to play a role in V. parahaemolyticus virulence. Recent advances in V. parahaemolyticus genomics identified several pathogenicity islands (VpaIs located on either chromosome in both epidemic and pandemic strains and comprising additional colonization factors, such as restriction-modification complexes, chemotaxis proteins, classical bacterial surface virulence factors, and putative colicins. Furthermore, studies indicate strains lacking toxins and genomic regions associated with pathogenicity may also be pathogenic, suggesting other important virulence factors remain to be identified. The unique repertoire of virulence factors identified to date, their occurrence and distribution in both epidemic and pandemic strains worldwide are described, with the aim of highlighting the complexity of V. parahaemolyticus pathogenicity as well as its dynamic genome.

  1. Virulence factors and antibiotic resistance in children with Helicobacter pylori gastritis.

    Science.gov (United States)

    Karabiber, Hamza; Selimoglu, Mukadder A; Otlu, Baris; Yildirim, Ozge; Ozer, Ali

    2014-05-01

    There are limited data regarding the pattern of Helicobacter pylori (Hp) antibiotic resistance and virulence factors in children. Evaluation of prevalence of drug resistance and virulence-factor genotype in children with Hp gastritis and to investigate whether there is any relation between drug resistance and genotype were our aims in this study. Ninety-eight children with polymerase chain reaction-positive Hp gastritis were included. Antimicrobial susceptibility was tested by disc diffusion method and polymerase chain reaction assays were used for the determination of virulence factors. The resistance rates to clarithromycin, metronidazole, and amoxicillin were 23.5%, 11.7%, and 3.9%, respectively. All strains carried vacA genotype, and 51%, 70.4%, 49%, 34.7%, and 25.5% were cagA-, cagE-, babA2-, iceA1-, and iceA2-positive, respectively. Of those 98 specimens, 81.6%, 19.4%, 38.8%, and 63.3% carried vacAs1, vacAs2, vacAm1, and vacAm2, respectively. Dominant vacA type was s1am2 (32.7%), followed by s1am1 (14.3%) and s2m2 (12.2%). Significant rates of clarithromycin resistance were observed in cagE-, iceA1-, babA2-, and vacAs1c-positive groups. In those with metronidazole resistance, vacAs1 and vacAs1c were more common (P < 0.05). The cagE-positive and vacA s1a/m2 genotypes, which are correlated with increased antibiotic resistance, were predominant in our population. In countries where Hp infection is prevalent, studies focusing on virulence factors and antibiotic susceptibility may provide anticipation of the prognosis and may be helpful to reduce morbidity and mortality.

  2. Virulence factors and biofilm production by isolates of Bacteroides fragilis recovered from dog intestinal tracts

    Directory of Open Access Journals (Sweden)

    Ana Catarina M. Reis

    2014-06-01

    Full Text Available Bacteroides fragilis colonizes dog guts both as a commensal and as an opportunistic pathogen. This study aims to evaluate virulence factors of 13 B. fragilis strains isolated from dog intestinal tracts and their ability for biofilm formation. Capsules were detected in all the evaluated strains. A total of 61.5% of all strains were biofilm producers. These attributes most likely play an important role in B. fragilis persistent colonization in the gut.

  3. Comparative genomics and transcriptomics of Escherichia coli isolates carrying virulence factors of both enteropathogenic and enterotoxigenic E. coli.

    Science.gov (United States)

    Hazen, Tracy H; Michalski, Jane; Luo, Qingwei; Shetty, Amol C; Daugherty, Sean C; Fleckenstein, James M; Rasko, David A

    2017-06-14

    Escherichia coli that are capable of causing human disease are often classified into pathogenic variants (pathovars) based on their virulence gene content. However, disease-associated hybrid E. coli, containing unique combinations of multiple canonical virulence factors have also been described. Such was the case of the E. coli O104:H4 outbreak in 2011, which caused significant morbidity and mortality. Among the pathovars of diarrheagenic E. coli that cause significant human disease are the enteropathogenic E. coli (EPEC) and enterotoxigenic E. coli (ETEC). In the current study we use comparative genomics, transcriptomics, and functional studies to characterize isolates that contain virulence factors of both EPEC and ETEC. Based on phylogenomic analysis, these hybrid isolates are more genomically-related to EPEC, but appear to have acquired ETEC virulence genes. Global transcriptional analysis using RNA sequencing, demonstrated that the EPEC and ETEC virulence genes of these hybrid isolates were differentially-expressed under virulence-inducing laboratory conditions, similar to reference isolates. Immunoblot assays further verified that the virulence gene products were produced and that the T3SS effector EspB of EPEC, and heat-labile toxin of ETEC were secreted. These findings document the existence and virulence potential of an E. coli pathovar hybrid that blurs the distinction between E. coli pathovars.

  4. Capsules, toxins and AtxA as virulence factors of emerging Bacillus cereus biovar anthracis.

    Directory of Open Access Journals (Sweden)

    Christophe Brézillon

    2015-04-01

    Full Text Available Emerging B. cereus strains that cause anthrax-like disease have been isolated in Cameroon (CA strain and Côte d'Ivoire (CI strain. These strains are unusual, because their genomic characterisation shows that they belong to the B. cereus species, although they harbour two plasmids, pBCXO1 and pBCXO2, that are highly similar to the pXO1 and pXO2 plasmids of B. anthracis that encode the toxins and the polyglutamate capsule respectively. The virulence factors implicated in the pathogenicity of these B. cereus bv anthracis strains remain to be characterised. We tested their virulence by cutaneous and intranasal delivery in mice and guinea pigs; they were as virulent as wild-type B. anthracis. Unlike as described for pXO2-cured B. anthracis, the CA strain cured of the pBCXO2 plasmid was still highly virulent, showing the existence of other virulence factors. Indeed, these strains concomitantly expressed a hyaluronic acid (HA capsule and the B. anthracis polyglutamate (PDGA capsule. The HA capsule was encoded by the hasACB operon on pBCXO1, and its expression was regulated by the global transcription regulator AtxA, which controls anthrax toxins and PDGA capsule in B. anthracis. Thus, the HA and PDGA capsules and toxins were co-regulated by AtxA. We explored the respective effect of the virulence factors on colonisation and dissemination of CA within its host by constructing bioluminescent mutants. Expression of the HA capsule by itself led to local multiplication and, during intranasal infection, to local dissemination to the adjacent brain tissue. Co-expression of either toxins or PDGA capsule with HA capsule enabled systemic dissemination, thus providing a clear evolutionary advantage. Protection against infection by B. cereus bv anthracis required the same vaccination formulation as that used against B. anthracis. Thus, these strains, at the frontier between B. anthracis and B. cereus, provide insight into how the monomorphic B. anthracis may have

  5. Capsules, Toxins and AtxA as Virulence Factors of Emerging Bacillus cereus Biovar anthracis

    Science.gov (United States)

    Corre, Jean-Philippe; Lander, Angelika; Franz, Tatjana; Monot, Marc; Couture-Tosi, Evelyne; Jouvion, Gregory; Leendertz, Fabian H.; Grunow, Roland; Mock, Michèle E.; Klee, Silke R.; Goossens, Pierre L.

    2015-01-01

    Emerging B. cereus strains that cause anthrax-like disease have been isolated in Cameroon (CA strain) and Côte d’Ivoire (CI strain). These strains are unusual, because their genomic characterisation shows that they belong to the B. cereus species, although they harbour two plasmids, pBCXO1 and pBCXO2, that are highly similar to the pXO1 and pXO2 plasmids of B. anthracis that encode the toxins and the polyglutamate capsule respectively. The virulence factors implicated in the pathogenicity of these B. cereus bv anthracis strains remain to be characterised. We tested their virulence by cutaneous and intranasal delivery in mice and guinea pigs; they were as virulent as wild-type B. anthracis. Unlike as described for pXO2-cured B. anthracis, the CA strain cured of the pBCXO2 plasmid was still highly virulent, showing the existence of other virulence factors. Indeed, these strains concomitantly expressed a hyaluronic acid (HA) capsule and the B. anthracis polyglutamate (PDGA) capsule. The HA capsule was encoded by the hasACB operon on pBCXO1, and its expression was regulated by the global transcription regulator AtxA, which controls anthrax toxins and PDGA capsule in B. anthracis. Thus, the HA and PDGA capsules and toxins were co-regulated by AtxA. We explored the respective effect of the virulence factors on colonisation and dissemination of CA within its host by constructing bioluminescent mutants. Expression of the HA capsule by itself led to local multiplication and, during intranasal infection, to local dissemination to the adjacent brain tissue. Co-expression of either toxins or PDGA capsule with HA capsule enabled systemic dissemination, thus providing a clear evolutionary advantage. Protection against infection by B. cereus bv anthracis required the same vaccination formulation as that used against B. anthracis. Thus, these strains, at the frontier between B. anthracis and B. cereus, provide insight into how the monomorphic B. anthracis may have emerged. PMID

  6. Capsules, toxins and AtxA as virulence factors of emerging Bacillus cereus biovar anthracis.

    Science.gov (United States)

    Brézillon, Christophe; Haustant, Michel; Dupke, Susann; Corre, Jean-Philippe; Lander, Angelika; Franz, Tatjana; Monot, Marc; Couture-Tosi, Evelyne; Jouvion, Gregory; Leendertz, Fabian H; Grunow, Roland; Mock, Michèle E; Klee, Silke R; Goossens, Pierre L

    2015-04-01

    Emerging B. cereus strains that cause anthrax-like disease have been isolated in Cameroon (CA strain) and Côte d'Ivoire (CI strain). These strains are unusual, because their genomic characterisation shows that they belong to the B. cereus species, although they harbour two plasmids, pBCXO1 and pBCXO2, that are highly similar to the pXO1 and pXO2 plasmids of B. anthracis that encode the toxins and the polyglutamate capsule respectively. The virulence factors implicated in the pathogenicity of these B. cereus bv anthracis strains remain to be characterised. We tested their virulence by cutaneous and intranasal delivery in mice and guinea pigs; they were as virulent as wild-type B. anthracis. Unlike as described for pXO2-cured B. anthracis, the CA strain cured of the pBCXO2 plasmid was still highly virulent, showing the existence of other virulence factors. Indeed, these strains concomitantly expressed a hyaluronic acid (HA) capsule and the B. anthracis polyglutamate (PDGA) capsule. The HA capsule was encoded by the hasACB operon on pBCXO1, and its expression was regulated by the global transcription regulator AtxA, which controls anthrax toxins and PDGA capsule in B. anthracis. Thus, the HA and PDGA capsules and toxins were co-regulated by AtxA. We explored the respective effect of the virulence factors on colonisation and dissemination of CA within its host by constructing bioluminescent mutants. Expression of the HA capsule by itself led to local multiplication and, during intranasal infection, to local dissemination to the adjacent brain tissue. Co-expression of either toxins or PDGA capsule with HA capsule enabled systemic dissemination, thus providing a clear evolutionary advantage. Protection against infection by B. cereus bv anthracis required the same vaccination formulation as that used against B. anthracis. Thus, these strains, at the frontier between B. anthracis and B. cereus, provide insight into how the monomorphic B. anthracis may have emerged.

  7. Relationship of Virulence Factors and Clinical Features in Keratitis Caused by Pseudomonas aeruginosa.

    Science.gov (United States)

    Oka, Naoko; Suzuki, Takashi; Ishikawa, Eri; Yamaguchi, Satoshi; Hayashi, Naoki; Gotoh, Naomasa; Ohashi, Yuichi

    2015-10-01

    To examine bacterial virulence factors in Pseudomonas aeruginosa isolates from contact lens (CL) wearers and non-CL wearers with P. aeruginosa keratitis, and to investigate relationships between virulence factors and clinical features of keratitis. The study involved 25 subjects including 18 CL and 7 non-CL-related P. aeruginosa keratitis patients. Slit-lamp photographs of all subjects were captured, and the focus occupancy ratio (FOR) was defined as the total focus area/entire cornea area, using image processing software. Twenty-five clinical P. aeruginosa isolates from keratitis were assessed for protease production, elastase production, biofilm formation, bacterial swimming and swarming motility, cell surface hydrophobicity, and genes encoding the type III secretion system (TTSS) effectors (ExoU and ExoS). Ring abscess was found in 9 of 18 CL-related P. aeruginosa keratitis cases (CL[+] ring[+] group) but not in another 9 cases (CL[+] ring[-] group). Expression or prevalence of virulence factors in P. aeruginosa isolates from the CL(+) ring(+) group, CL(+) ring(-) group, and CL(-) group were compared. The FOR for CL(+) ring(+) or CL(-) was higher than for CL(+) ring(-) (P keratitis.

  8. Cytolethal distending toxin as virulence factor, protective antigen, and target for vaccine development

    Directory of Open Access Journals (Sweden)

    Lagergård T

    2012-12-01

    Full Text Available Teresa Lagergård,1 Jerry Keith21Institute of Biomedicine, Department of Microbiology and Immunology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden; 2Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD, NIH, Bethesda, MD, USAAbstract: This review explores the cytolethal distending toxin (CDT as a virulence factor, protective antigen, and a vaccine candidate in diseases caused by the following bacterial pathogens: Haemophilus ducreyi (HdCDT, Aggregatibacter actinomycetemcomitans, Campylobacter jejuni, and Helicobacter hepaticus. The review highlights some of the important evidence indicating that CDT is not only a commonly invoked virulence factor involved in pathogenesis of infection caused by these bacteria, but is also a protective antigen, such that specific antibodies will neutralize cell damage caused by the toxin. This justifies the development of toxoids as vaccine candidates. The first immunogenic toxoid was produced by formaldehyde treatment of HdCDT and has been used to study the involvement of antibodies in protection against infection and its use as a future vaccine component. The development of such toxoid vaccines may facilitate the studies of protection and immunoprophylaxis in diseases caused by CDT-producing bacteria.Keywords: cytolethal distending toxin, virulence factor, protective antigen, Haemophilus ducreyi, Aggregatibacter actinomycetemcomitans, Campylobacter jejuni, toxoid vaccine

  9. Virulence factors in Proteus bacteria from biofilm communities of catheter-associated urinary tract infections.

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    Hola, Veronika; Peroutkova, Tereza; Ruzicka, Filip

    2012-07-01

    More than 40% of nosocomial infections are those of the urinary tract, most of these occurring in catheterized patients. Bacterial colonization of the urinary tract and catheters results not only in infection, but also various complications, such as blockage of catheters with crystalline deposits of bacterial origin, generation of gravels and pyelonephritis. The diversity of the biofilm microbial community increases with duration of catheter emplacement. One of the most important pathogens in this regard is Proteus mirabilis. The aims of this study were to identify and assess particular virulence factors present in catheter-associated urinary tract infection (CAUTI) isolates, their correlation and linkages: three types of motility (swarming, swimming and twitching), the ability to swarm over urinary catheters, biofilm production in two types of media, urease production and adherence of bacterial cells to various types of urinary tract catheters. We examined 102 CAUTI isolates and 50 isolates taken from stool samples of healthy people. Among the microorganisms isolated from urinary catheters, significant differences were found in biofilm-forming ability and the swarming motility. In comparison with the control group, the microorganisms isolated from urinary catheters showed a wider spectrum of virulence factors. The virulence factors (twitching motility, swimming motility, swarming over various types of catheters and biofilm formation) were also more intensively expressed. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  10. Induction of virulence factors in Giardia duodenalis independent of host attachment

    Science.gov (United States)

    Emery, Samantha J.; Mirzaei, Mehdi; Vuong, Daniel; Pascovici, Dana; Chick, Joel M.; Lacey, Ernest; Haynes, Paul A.

    2016-01-01

    Giardia duodenalis is responsible for the majority of parasitic gastroenteritis in humans worldwide. Host-parasite interaction models in vitro provide insights into disease and virulence and help us to understand pathogenesis. Using HT-29 intestinal epithelial cells (IEC) as a model we have demonstrated that initial sensitisation by host secretions reduces proclivity for trophozoite attachment, while inducing virulence factors. Host soluble factors triggered up-regulation of membrane and secreted proteins, including Tenascins, Cathepsin-B precursor, cystatin, and numerous Variant-specific Surface Proteins (VSPs). By comparison, host-cell attached trophozoites up-regulated intracellular pathways for ubiquitination, reactive oxygen species (ROS) detoxification and production of pyridoxal phosphate (PLP). We reason that these results demonstrate early pathogenesis in Giardia involves two independent host-parasite interactions. Motile trophozoites respond to soluble secreted signals, which deter attachment and induce expression of virulence factors. Trophozoites attached to host cells, in contrast, respond by up-regulating intracellular pathways involved in clearance of ROS, thus anticipating the host defence response. PMID:26867958

  11. Porphyromonas gingivalis Uses Specific Domain Rearrangements and Allelic Exchange to Generate Diversity in Surface Virulence Factors

    Science.gov (United States)

    Dashper, Stuart G.; Mitchell, Helen L.; Seers, Christine A.; Gladman, Simon L.; Seemann, Torsten; Bulach, Dieter M.; Chandry, P. Scott; Cross, Keith J.; Cleal, Steven M.; Reynolds, Eric C.

    2017-01-01

    Porphyromonas gingivalis is a keystone pathogen of chronic periodontitis. The virulence of P. gingivalis is reported to be strain related and there are currently a number of strain typing schemes based on variation in capsular polysaccharide, the major and minor fimbriae and adhesin domains of Lys-gingipain (Kgp), amongst other surface proteins. P. gingivalis can exchange chromosomal DNA between strains by natural competence and conjugation. The aim of this study was to determine the genetic variability of P. gingivalis strains sourced from international locations over a 25-year period and to determine if variability in surface virulence factors has a phylogenetic basis. Whole genome sequencing was performed on 13 strains and comparison made to 10 previously sequenced strains. A single nucleotide polymorphism-based phylogenetic analysis demonstrated a shallow tri-lobed phylogeny. There was a high level of reticulation in the phylogenetic network, demonstrating extensive horizontal gene transfer between the strains. Two highly conserved variants of the catalytic domain of the major virulence factor the Kgp proteinase (KgpcatI and KgpcatII) were found. There were three variants of the fourth Kgp C-terminal cleaved adhesin domain. Specific variants of the cell surface proteins FimA, FimCDE, MfaI, RagAB, Tpr, and PrtT were also identified. The occurrence of all these variants in the P. gingivalis strains formed a mosaic that was not related to the SNP-based phylogeny. In conclusion P. gingivalis uses domain rearrangements and genetic exchange to generate diversity in specific surface virulence factors. PMID:28184216

  12. Detection of Methicillin Resistance and Various Virulence Factors in Staphylococcus aureus Strains Isolated from Nasal Carriers

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    Hatice Türk Dağı

    2015-06-01

    Full Text Available Background: Staphylococus aureus can be found as a commensal on skin and nasal flora or it may cause local and invasive infections. S. aureus has a large number of virulence factors. Aims: To investigate the methicillin resistance and frequency of various virulence factors in S. aureus nasal isolates. Study Design: Descriptive study. Methods: Nasal samples collected from university students were cultured in media. S. aureus was identified by conventional methods and the Staphyloslide latex test (Becton Dickinson, Sparks, USA. Antibiotic susceptibility tests were conducted, and the methicillin resistance was determined. The mecA, nuc, pvl and staphylococcal toxin genes were examined by polymerase chain reaction (PCR. Results: S. aureus was isolated in 104 of 600 (17.3% nasal samples. In total, 101 (97.1% S. aureus isolates were methicillin-sensitive and the remaining 3 (2.9% were methicillin-resistant. Furthermore, all but five isolates carried at least one staphylococcal enterotoxin gene, with seg being predominant. The tst and eta genes were determined in 29 (27.9%, and 3 (2.9% isolates, respectively. None of the S. aureus isolates harbored see, etb, and pvl genes. Conclusion: A moderate rate of S. aureus carriage and low frequency of MRSA were detected in healthy students. S. aureus isolates had a high prevalence of staphylococcal enterotoxin genes and the tst gene. In this study, a large number of virulence factors were examined in S. aureus nasal isolates, and the data obtained from this study can be used for monitoring the prevalence of virulence genes in S. aureus strains isolated from nasal carriers.

  13. Genome sequence of the endosymbiont Rickettsia peacockii and comparison with virulent Rickettsia rickettsii: identification of virulence factors.

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    Roderick F Felsheim

    2009-12-01

    Full Text Available Rickettsia peacockii, also known as the East Side Agent, is a non-pathogenic obligate intracellular bacterium found as an endosymbiont in Dermacentor andersoni ticks in the western USA and Canada. Its presence in ticks is correlated with reduced prevalence of Rickettsia rickettsii, the agent of Rocky Mountain Spotted Fever. It has been proposed that a virulent SFG rickettsia underwent changes to become the East Side Agent. We determined the genome sequence of R. peacockii and provide a comparison to a closely related virulent R. rickettsii. The presence of 42 chromosomal copies of the ISRpe1 transposon in the genome of R. peacockii is associated with a lack of synteny with the genome of R. rickettsii and numerous deletions via recombination between transposon copies. The plasmid contains a number of genes from distantly related organisms, such as part of the glycosylation island of Pseudomonas aeruginosa. Genes deleted or mutated in R. peacockii which may relate to loss of virulence include those coding for an ankyrin repeat containing protein, DsbA, RickA, protease II, OmpA, ScaI, and a putative phosphoethanolamine transferase. The gene coding for the ankyrin repeat containing protein is especially implicated as it is mutated in R. rickettsii strain Iowa, which has attenuated virulence. Presence of numerous copies of the ISRpe1 transposon, likely acquired by lateral transfer from a Cardinium species, are associated with extensive genomic reorganization and deletions. The deletion and mutation of genes possibly involved in loss of virulence have been identified by this genomic comparison. It also illustrates that the introduction of a transposon into the genome can have varied effects; either correlating with an increase in pathogenicity as in Francisella tularensis or a loss of pathogenicity as in R. peacockii and the recombination enabled by multiple transposon copies can cause significant deletions in some genomes while not in others.

  14. COORDINATED VIRULENCE FACTORS OF ZOONOTIC PATHOGEN Salmonella Typhimurium ASSOCIATED WITH SYSTEMIC DISEASE

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    Ermin Schadich

    2013-08-01

    Full Text Available  The pivotal virulence factors of foodborne zoonotic pathogen Salmonella enterica serotype Typhimurium associated with pathogenesis of systemic disease of humans and mice are the effectors of type three secretion systems. They are encoded by genes located on two different gene clusters named Salmonella pathogenicity island 1 and 2 (SPI-1 and SPI-2 and Salmonella plasmid virulence locus whose expressions are coordinated by regulatory networks in spatial and temporal manners. Secretion of the SPI-1 effectors required for bacterial internalization into specific compartments called Salmonella- containing vacuole (SCV of infected intestinal epithelial cells, is induced by environmental conditions via Hil transcription factors network. Secretion of SPI-2 and plasmid effectors required for bacterial survival inside of the SCVs of these cells and subsequently infected phagocytic cells, systemic spread, immunosuppression and cytotoxicity, is coordinated by broader regulatory network with the two response regulators, SsrB and SlyA, as the terminal regulators that integrate multiple environmental signals. Key words: Salmonella Typhimurium, effectors, virulence, systemic disease

  15. Plant Growth-Promoting Genes can Switch to be Virulence Factors via Horizontal Gene Transfer.

    Science.gov (United States)

    Stritzler, Margarita; Soto, Gabriela; Ayub, Nicolás

    2018-02-23

    There are increasing evidences that horizontal gene transfer (HGT) is a critical mechanism of bacterial evolution, while its complete impact remains unclear. A main constraint of HGT effects on microbial evolution seems to be the conservation of the function of the horizontally transferred genes. From this perspective, inflexible nomenclature and functionality criteria have been established for some mobile genetic elements such as pathogenic and symbiotic islands. Adhesion is a universal prerequisite for both beneficial and pathogenic plant-microbe interactions, and thus, adhesion systems (e.g., the Lap cluster) are candidates to have a dual function depending on the genomic background. In this study, we showed that the virulent factor Lap of the phytopathogen Erwinia carotovora SCRI1043, which is located within a genomic island, was acquired by HGT and probably derived from Pseudomonas. The transformation of the phytopathogen Erwinia pyrifoliae Ep1/96 with the beneficial factor Lap from the plant growth-promoting bacterium Pseudomonas fluorescens Pf-5 significantly increased its natural virulence, experimentally recapitulating the beneficial-to-virulence functional switch of the Lap cluster via HGT. To our knowledge, this is the first report of a functional switch of an individual gene or a cluster of genes mediated by HGT.

  16. Variable virulence factors in Burkholderia pseudomallei (melioidosis associated with human disease.

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    Derek S Sarovich

    Full Text Available Burkholderia pseudomallei is a Gram-negative environmental bacterium that causes melioidosis, a potentially life-threatening infectious disease affecting mammals, including humans. Melioidosis symptoms are both protean and diverse, ranging from mild, localized skin infections to more severe and often fatal presentations including pneumonia, septic shock with multiple internal abscesses and occasionally neurological involvement. Several ubiquitous virulence determinants in B. pseudomallei have already been discovered. However, the molecular basis for differential pathogenesis has, until now, remained elusive. Using clinical data from 556 Australian melioidosis cases spanning more than 20 years, we identified a Burkholderia mallei-like actin polymerization bimA(Bm gene that is strongly associated with neurological disease. We also report that a filamentous hemagglutinin gene, fhaB3, is associated with positive blood cultures but is negatively correlated with localized skin lesions without sepsis. We show, for the first time, that variably present virulence factors play an important role in the pathogenesis of melioidosis. Collectively, our study provides a framework for assessing other non-ubiquitous bacterial virulence factors and their association with disease, such as candidate loci identified from large-scale microbial genome-wide association studies.

  17. Proteases from Entamoeba spp. and Pathogenic Free-Living Amoebae as Virulence Factors.

    Science.gov (United States)

    Serrano-Luna, Jesús; Piña-Vázquez, Carolina; Reyes-López, Magda; Ortiz-Estrada, Guillermo; de la Garza, Mireya

    2013-01-01

    The standard reference for pathogenic and nonpathogenic amoebae is the human parasite Entamoeba histolytica; a direct correlation between virulence and protease expression has been demonstrated for this amoeba. Traditionally, proteases are considered virulence factors, including those that produce cytopathic effects in the host or that have been implicated in manipulating the immune response. Here, we expand the scope to other amoebae, including less-pathogenic Entamoeba species and highly pathogenic free-living amoebae. In this paper, proteases that affect mucin, extracellular matrix, immune system components, and diverse tissues and cells are included, based on studies in amoebic cultures and animal models. We also include proteases used by amoebae to degrade iron-containing proteins because iron scavenger capacity is currently considered a virulence factor for pathogens. In addition, proteases that have a role in adhesion and encystation, which are essential for establishing and transmitting infection, are discussed. The study of proteases and their specific inhibitors is relevant to the search for new therapeutic targets and to increase the power of drugs used to treat the diseases caused by these complex microorganisms.

  18. Variable virulence factors in Burkholderia pseudomallei (melioidosis) associated with human disease.

    Science.gov (United States)

    Sarovich, Derek S; Price, Erin P; Webb, Jessica R; Ward, Linda M; Voutsinos, Marcos Y; Tuanyok, Apichai; Mayo, Mark; Kaestli, Mirjam; Currie, Bart J

    2014-01-01

    Burkholderia pseudomallei is a Gram-negative environmental bacterium that causes melioidosis, a potentially life-threatening infectious disease affecting mammals, including humans. Melioidosis symptoms are both protean and diverse, ranging from mild, localized skin infections to more severe and often fatal presentations including pneumonia, septic shock with multiple internal abscesses and occasionally neurological involvement. Several ubiquitous virulence determinants in B. pseudomallei have already been discovered. However, the molecular basis for differential pathogenesis has, until now, remained elusive. Using clinical data from 556 Australian melioidosis cases spanning more than 20 years, we identified a Burkholderia mallei-like actin polymerization bimA(Bm) gene that is strongly associated with neurological disease. We also report that a filamentous hemagglutinin gene, fhaB3, is associated with positive blood cultures but is negatively correlated with localized skin lesions without sepsis. We show, for the first time, that variably present virulence factors play an important role in the pathogenesis of melioidosis. Collectively, our study provides a framework for assessing other non-ubiquitous bacterial virulence factors and their association with disease, such as candidate loci identified from large-scale microbial genome-wide association studies.

  19. Proteases from Entamoeba spp. and Pathogenic Free-Living Amoebae as Virulence Factors

    Science.gov (United States)

    Serrano-Luna, Jesús; Piña-Vázquez, Carolina; Reyes-López, Magda; Ortiz-Estrada, Guillermo

    2013-01-01

    The standard reference for pathogenic and nonpathogenic amoebae is the human parasite Entamoeba histolytica; a direct correlation between virulence and protease expression has been demonstrated for this amoeba. Traditionally, proteases are considered virulence factors, including those that produce cytopathic effects in the host or that have been implicated in manipulating the immune response. Here, we expand the scope to other amoebae, including less-pathogenic Entamoeba species and highly pathogenic free-living amoebae. In this paper, proteases that affect mucin, extracellular matrix, immune system components, and diverse tissues and cells are included, based on studies in amoebic cultures and animal models. We also include proteases used by amoebae to degrade iron-containing proteins because iron scavenger capacity is currently considered a virulence factor for pathogens. In addition, proteases that have a role in adhesion and encystation, which are essential for establishing and transmitting infection, are discussed. The study of proteases and their specific inhibitors is relevant to the search for new therapeutic targets and to increase the power of drugs used to treat the diseases caused by these complex microorganisms. PMID:23476670

  20. Functional association between the Helicobacter pylori virulence factors VacA and CagA.

    Science.gov (United States)

    Argent, Richard H; Thomas, Rachael J; Letley, Darren P; Rittig, Michael G; Hardie, Kim R; Atherton, John C

    2008-02-01

    The Helicobacter pylori virulence factors CagA and VacA are implicated in the development of gastroduodenal diseases. Most strains possessing CagA also possess the more virulent vacuolating form of VacA. This study assessed the significance of possession of both virulence factors in terms of their effect on gastric epithelial cells, using a set of minimally passaged, isogenic VacA, CagA and CagE mutants in H. pylori strains 60190 and 84-183. The cagA and cagE mutants were found to significantly increase VacA-induced vacuolation of epithelial cells, and the vacA mutants significantly increased CagA-induced cellular elongations, compared with wild-type strains, indicating that CagA reduces vacuolation and VacA reduces hummingbird formation. Although epithelial cells incubated with the wild-type H. pylori strains may display both vacuolation and hummingbird formation, it was found that (i) hummingbird length was significantly reduced in vacuolated cells compared with those without vacuolation; (ii) the number of vacuoles was significantly reduced in vacuolated cells with hummingbird formation compared with those without hummingbirds; and (iii) cells displaying extensive vacuolation did not subsequently form hummingbirds and vice versa. VacA did not affect the phosphorylation of CagA. These data show that VacA and CagA downregulate each other's effects on epithelial cells, potentially allowing H. pylori interaction with cells whilst avoiding excessive cellular damage.

  1. Identification and Structural Basis of Binding to Host Lung Glycogen by Streptococcal Virulence Factors

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    Lammerts van Bueren,A.; Higgins, M.; Wang, D.; Burke, R.; Boraston, A.

    2007-01-01

    The ability of pathogenic bacteria to recognize host glycans is often essential to their virulence. Here we report structure-function studies of previously uncharacterized glycogen-binding modules in the surface-anchored pullulanases from Streptococcus pneumoniae (SpuA) and Streptococcus pyogenes (PulA). Multivalent binding to glycogen leads to a strong interaction with alveolar type II cells in mouse lung tissue. X-ray crystal structures of the binding modules reveal a novel fusion of tandem modules into single, bivalent functional domains. In addition to indicating a structural basis for multivalent attachment, the structure of the SpuA modules in complex with carbohydrate provides insight into the molecular basis for glycogen specificity. This report provides the first evidence that intracellular lung glycogen may be a novel target of pathogenic streptococci and thus provides a rationale for the identification of the streptococcal {alpha}-glucan-metabolizing machinery as virulence factors.

  2. Extracellular Vesicles from Trypanosoma brucei Mediate Virulence Factor Transfer and Cause Host Anemia.

    Science.gov (United States)

    Szempruch, Anthony J; Sykes, Steven E; Kieft, Rudo; Dennison, Lauren; Becker, Allison C; Gartrell, Anzio; Martin, William J; Nakayasu, Ernesto S; Almeida, Igor C; Hajduk, Stephen L; Harrington, John M

    2016-01-14

    Intercellular communication between parasites and with host cells provides mechanisms for parasite development, immune evasion, and disease pathology. Bloodstream African trypanosomes produce membranous nanotubes that originate from the flagellar membrane and disassociate into free extracellular vesicles (EVs). Trypanosome EVs contain several flagellar proteins that contribute to virulence, and Trypanosoma brucei rhodesiense EVs contain the serum resistance-associated protein (SRA) necessary for human infectivity. T. b. rhodesiense EVs transfer SRA to non-human infectious trypanosomes, allowing evasion of human innate immunity. Trypanosome EVs can also fuse with mammalian erythrocytes, resulting in rapid erythrocyte clearance and anemia. These data indicate that trypanosome EVs are organelles mediating non-hereditary virulence factor transfer and causing host erythrocyte remodeling, inducing anemia. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Flavone reduces the production of virulence factors, staphyloxanthin and α-hemolysin, in Staphylococcus aureus.

    Science.gov (United States)

    Lee, Jin-Hyung; Park, Joo-Hyeon; Cho, Moo Hwan; Lee, Jintae

    2012-12-01

    Staphylococcus aureus is a leading cause of nosocomial infections due to its resistance to diverse antibiotics. This bacterium produces a large number of extracellular virulence factors that are closely associated with specific diseases. In this study, diverse plant flavonoids were investigated to identify a novel anti-virulence compound against two S. aureus strains. Flavone, a backbone compound of flavonoids, at subinhibitory concentration (50 μg/mL), markedly reduced the production of staphyloxanthin and α-hemolysin. This staphyloxanthin reduction rendered the S. aureus cells 100 times more vulnerable to hydrogen peroxide in the presence of flavone. In addition, flavone significantly decreased the hemolysis of human red blood by S. aureus, and the transcriptional level of α-hemolysin gene hla and a global regulator gene sae in S. aureus cells. This finding supported the usefulness of flavone as a potential antivirulence agent against antibiotic-resistant S. aureus.

  4. Staphylococcus aureus Hijacks a Skin Commensal to Intensify Its Virulence: Immunization Targeting β-Hemolysin and CAMP Factor

    OpenAIRE

    Lo, Chih-Wei; Lai, Yiu-Kay; Liu, Yu-Tsueng; Gallo, Richard L.; Huang, Chun-Ming

    2010-01-01

    The need for a new anti-Staphylococcus aureus therapy that can effectively cripple bacterial infection, neutralize secretory virulence factors, and lower the risk of creating bacterial resistance is undisputed. Here, we propose what is, to our knowledge, a previously unreported infectious mechanism by which S. aureus may commandeer Propionibacterium acnes, a key member of the human skin microbiome, to spread its invasion and highlight two secretory virulence factors (S. aureus β-hemolysin and...

  5. Clustered, regularly interspaced short palindromic repeat (CRISPR) diversity and virulence factor distribution in avian Escherichia coli.

    Science.gov (United States)

    Fu, Qiang; Su, Zhixin; Cheng, Yuqiang; Wang, Zhaofei; Li, Shiyu; Wang, Heng'an; Sun, Jianhe; Yan, Yaxian

    In order to investigate the diverse characteristics of clustered, regularly interspaced short palindromic repeat (CRISPR) arrays and the distribution of virulence factor genes in avian Escherichia coli, 80 E. coli isolates obtained from chickens with avian pathogenic E. coli (APEC) or avian fecal commensal E. coli (AFEC) were identified. Using the multiplex polymerase chain reaction (PCR), five genes were subjected to phylogenetic typing and examined for CRISPR arrays to study genetic relatedness among the strains. The strains were further analyzed for CRISPR loci and virulence factor genes to determine a possible association between their CRISPR elements and their potential virulence. The strains were divided into five phylogenetic groups: A, B1, B2, D and E. It was confirmed that two types of CRISPR arrays, CRISPR1 and CRISPR2, which contain up to 246 distinct spacers, were amplified in most of the strains. Further classification of the isolates was achieved by sorting them into nine CRISPR clusters based on their spacer profiles, which indicates a candidate typing method for E. coli. Several significant differences in invasion-associated gene distribution were found between the APEC isolates and the AFEC isolates. Our results identified the distribution of 11 virulence genes and CRISPR diversity in 80 strains. It was demonstrated that, with the exception of iucD and aslA, there was no sharp demarcation in the gene distribution between the pathogenic (APEC) and commensal (AFEC) strains, while the total number of indicated CRISPR spacers may have a positive correlation with the potential pathogenicity of the E. coli isolates. Copyright © 2016. Published by Elsevier Masson SAS.

  6. Network analysis of S. aureus response to ramoplanin reveals modules for virulence factors and resistance mechanisms and characteristic novel genes.

    Science.gov (United States)

    Subramanian, Devika; Natarajan, Jeyakumar

    2015-12-10

    Staphylococcus aureus is a major human pathogen and ramoplanin is an antimicrobial attributed for effective treatment. The goal of this study was to examine the transcriptomic profiles of ramoplanin sensitive and resistant S. aureus to identify putative modules responsible for virulence and resistance-mechanisms and its characteristic novel genes. The dysregulated genes were used to reconstruct protein functional association networks for virulence-factors and resistance-mechanisms individually. Strong link between metabolic-pathways and development of virulence/resistance is suggested. We identified 15 putative modules of virulence factors. Six hypothetical genes were annotated with novel virulence activity among which SACOL0281 was discovered to be an essential virulence factor EsaD. The roles of MazEF toxin-antitoxin system, SACOL0202/SACOL0201 two-component system and that of amino-sugar and nucleotide-sugar metabolism in virulence are also suggested. In addition, 14 putative modules of resistance mechanisms including modules of ribosomal protein-coding genes and metabolic pathways such as biotin-synthesis, TCA-cycle, riboflavin-biosynthesis, peptidoglycan-biosynthesis etc. are also indicated. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Adhesion and virulence factor properties of Enterococci isolated from clinical samples in Iran

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    Hossein Samadi Kafil

    2013-01-01

    Full Text Available Introduction: Enterococci rank among leading causes of nosocomial bacteremia, urinary tract infections and community acquired endocarditis. The aim of the present study was to investigate the presence of virulence factors in Enterococci strains isolated from clinical samples in Iranian Educational hospitals. Methodology: Presence of aggregation substance (asa, extracellular surface protein (esp, Enterococcus faecalis antigen A (efaA, adhesin of collagen from E. faecalis (ace, endocarditis and biofilm-associated pilli (ebp as colonization factors and cytolysin (cyl, gelatinase (gel and hyaloronidase (hyl as secretary factors were investigated in isolates. A total of 201 clinical isolates of Enterococci were collected in 2009-2010 from eight educational hospitals. After deoxyribonucleic acid extraction, they were examined for presence of virulence factors by polymerase chain reaction. Results: E. faecalis and Enterococcus faecium were isolated from 56.9% to 43.1%, respectively. Resistance to vancomycin and gentamicin were 33.8% and 83.9% in E. faecium isolates and 16.3% and 88.1% in E. faecalis isolates respectively. Colonization factors were found to be more prevalent in E. faecalis isolates and almost all isolates of E. faecalis had ace, ebp and efaA genes. Esp gene had a higher rate of distribution in Enterococci isolates (75.1% in this study compared with previous studies. One of E. faecalis isolates contained hyl gene, but 38.8% of E. faecium isolates had it. Mutual exclusive were present between hyl and efaA in all E. faecium isolates and 69.7% of E. faecium hyl - positive isolates were esp positive. Conclusion: According to these results, virulence genes were more prevalent in E. faecalis isolates and E. faecalis had more potential pathogenesis for initiating an infection; however because of E. faeciums higher antibiotic resistance, we have been facing higher E. faecium infections in hospitalized patients.

  8. Loss of Lipid Virulence Factors Reduces the Efficacy of the BCG Vaccine

    Science.gov (United States)

    Tran, Vanessa; Ahn, Sang Kyun; Ng, Mark; Li, Ming; Liu, Jun

    2016-01-01

    Bacille Calmette-Guérin (BCG), an attenuated strain of Mycobacterium bovis, is the only vaccine available for tuberculosis (TB) control. BCG comprises a number of substrains that exhibit genetic and biochemical differences. Whether and how these differences affect BCG efficacy remain unknown. Compared to other BCG strains, BCG-Japan, -Moreau, and -Glaxo are defective in the production of phthiocerol dimycocerosates (PDIMs) and phenolic glycolipids (PGLs), two lipid virulence factors. To determine if the loss of PDIMs/PGLs affects BCG efficacy, we constructed a PDIM/PGL-deficient strain of BCG-Pasteur by deleting fadD28, and compared virulence, immunogenicity, and protective efficacy in animal models. SCID mouse infection experiments showed that ∆fadD28 was more attenuated than wild type (WT). The ∆fadD28 and WT strains induced equivalent levels of antigen specific IFN-γ by CD4+ and CD8+ T cells; however, ∆fadD28 was less effective against Mycobacterium tuberculosis challenge in both BALB/c mice and guinea pigs. These results indicate that the loss of PIDMs/PGLs reduces the virulence and protective efficacy of BCG. Since the loss of PDIMs/PGLs occurs naturally in a subset of BCG strains, it also suggests that these strains may have been over-attenuated, which compromises their effectiveness. Our finding has important implications for current BCG programs and future vaccine development. PMID:27357109

  9. Paenibacillus larvae enolase as a virulence factor in honeybee larvae infection.

    Science.gov (United States)

    Antúnez, Karina; Anido, Matilde; Arredondo, Daniela; Evans, Jay D; Zunino, Pablo

    2011-01-10

    Paenibacillus larvae is a gram-positive spore-forming bacteria, causative agent of American Foulbrood (AFB), a severe disease affecting larvae of the honeybee Apis mellifera. In an attempt to detect potential virulence factors secreted by P. larvae, we identified an enolase among different secreted proteins. Although this protein is a cytosolic enzyme involved in glycolytic pathways, it has been related to virulence. The aim of the present work was to evaluate its role during the infection of honeybee larvae. Toxicity assays showed that enolase was highly toxic and immunogenic to honeybee larvae. Its production was detected inside P. larvae vegetative cells, on the surface of P. larvae spores and secreted to the external growth medium. P. larvae enolase production was also confirmed in vivo, during the infection of honeybee larvae. This protein was able to hydrolyze milk proteins as described for P. larvae, suggesting that could be involved in larval degradation, maybe through the plasmin(ogen) system. These results suggest that P. larvae enolase may have a role in virulence and could contribute to a general insight about insect-pathogen interaction mechanisms. Copyright © 2010 Elsevier B.V. All rights reserved.

  10. FNR Regulates the Expression of Important Virulence Factors Contributing to the Pathogenicity of Avian Pathogenic Escherichia coli.

    Science.gov (United States)

    Barbieri, Nicolle L; Vande Vorde, Jessica A; Baker, Alison R; Horn, Fabiana; Li, Ganwu; Logue, Catherine M; Nolan, Lisa K

    2017-01-01

    Avian pathogenic Escherichia coli (APEC) is the etiologic agent of colibacillosis, an important cause of morbidity and mortality in poultry. Though, many virulence factors associated with APEC pathogenicity are known, their regulation remains unclear. FNR (fumarate and nitrate reduction) is a well-known global regulator that works as an oxygen sensor and has previously been described as a virulence regulator in bacterial pathogens. The goal of this study was to examine the role of FNR in the regulation of APEC virulence factors, such as Type I fimbriae, and processes such as adherence and invasion, type VI secretion, survival during oxidative stress, and growth in iron-restricted environments. To accomplish this goal, APEC O1, a well-characterized, highly virulent, and fully sequenced strain of APEC harboring multiple virulence mechanisms, some of which are plasmid-linked, was compared to its FNR mutant for expression of various virulence traits. Deletion of FNR was found to affect APEC O1's adherence, invasion and expression of ompT, a plasmid-encoded outer membrane protein, type I fimbriae, and aatA, encoding an autotransporter. Indeed, the fnr- mutant showed an 8-fold reduction in expression of type I fimbriae and a highly significant (P APEC O1's growth in iron-deficient media and survival during oxidative stress with the mutant showing a 4-fold decrease in tolerance to oxidative stress, as compared to the wild type. Thus, our results suggest that FNR functions as an important regulator of APEC virulence.

  11. Punicalagin inhibits Salmonella virulence factors and has anti-quorum-sensing potential.

    Science.gov (United States)

    Li, Guanghui; Yan, Chunhong; Xu, Yunfeng; Feng, Yuqing; Wu, Qian; Lv, Xiaoying; Yang, Baowei; Wang, Xin; Xia, Xiaodong

    2014-10-01

    Punicalagin, an essential component of pomegranate rind, has been demonstrated to possess antimicrobial activity against several food-borne pathogens, but its activity on the virulence of pathogens and its anti-quorum-sensing (anti-QS) potential have been rarely reported. This study investigated the efficacy of subinhibitory concentrations of punicalagin on Salmonella virulence factors and QS systems. A broth microdilution method was used to determine the MICs of punicalagin for 10 Salmonella strains. Motility assay and quantitative reverse transcription (RT)-PCR were performed to evaluate the effects of punicalagin on the virulence attributes and QS-related genes of Salmonella. The MICs of punicalagin for several Salmonella strains ranged from 250 to 1,000 μg/ml. Motility assays showed that punicalagin, at 1/16× MIC and 1/32× MIC, significantly decreased bacterial swimming and swarming motility, which corresponded to downregulation of the motility-related genes (fliA, fliY, fljB, flhC, and fimD) in RT-PCR assays. RT-PCR also revealed that punicalagin downregulated the expression of most of the selected genes involved in Salmonella virulence. Moreover, a QS inhibition assay indicated that punicalagin dose dependently inhibited the production of violacein by Chromobacterium violaceum and repressed the expression of QS-related genes (sdiA and srgE) in Salmonella. In addition, punicalagin significantly reduced Salmonella invasion of colonic cells (Ppunicalagin has the potential to be developed as an alternative or supplemental agent for prevention of Salmonella infection. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  12. Molecular adaptation of a plant-bacterium outer membrane protease towards plague virulence factor Pla.

    Science.gov (United States)

    Haiko, Johanna; Laakkonen, Liisa; Westerlund-Wikström, Benita; Korhonen, Timo K

    2011-02-11

    Omptins are a family of outer membrane proteases that have spread by horizontal gene transfer in Gram-negative bacteria that infect vertebrates or plants. Despite structural similarity, the molecular functions of omptins differ in a manner that reflects the life style of their host bacteria. To simulate the molecular adaptation of omptins, we applied site-specific mutagenesis to make Epo of the plant pathogenic Erwinia pyrifoliae exhibit virulence-associated functions of its close homolog, the plasminogen activator Pla of Yersinia pestis. We addressed three virulence-associated functions exhibited by Pla, i.e., proteolytic activation of plasminogen, proteolytic degradation of serine protease inhibitors, and invasion into human cells. Pla and Epo expressed in Escherichia coli are both functional endopeptidases and cleave human serine protease inhibitors, but Epo failed to activate plasminogen and to mediate invasion into a human endothelial-like cell line. Swapping of ten amino acid residues at two surface loops of Pla and Epo introduced plasminogen activation capacity in Epo and inactivated the function in Pla. We also compared the structure of Pla and the modeled structure of Epo to analyze the structural variations that could rationalize the different proteolytic activities. Epo-expressing bacteria managed to invade human cells only after all extramembranous residues that differ between Pla and Epo and the first transmembrane β-strand had been changed. We describe molecular adaptation of a protease from an environmental setting towards a virulence factor detrimental for humans. Our results stress the evolvability of bacterial β-barrel surface structures and the environment as a source of progenitor virulence molecules of human pathogens.

  13. Molecular adaptation of a plant-bacterium outer membrane protease towards plague virulence factor Pla

    Directory of Open Access Journals (Sweden)

    Westerlund-Wikström Benita

    2011-02-01

    Full Text Available Abstract Background Omptins are a family of outer membrane proteases that have spread by horizontal gene transfer in Gram-negative bacteria that infect vertebrates or plants. Despite structural similarity, the molecular functions of omptins differ in a manner that reflects the life style of their host bacteria. To simulate the molecular adaptation of omptins, we applied site-specific mutagenesis to make Epo of the plant pathogenic Erwinia pyrifoliae exhibit virulence-associated functions of its close homolog, the plasminogen activator Pla of Yersinia pestis. We addressed three virulence-associated functions exhibited by Pla, i.e., proteolytic activation of plasminogen, proteolytic degradation of serine protease inhibitors, and invasion into human cells. Results Pla and Epo expressed in Escherichia coli are both functional endopeptidases and cleave human serine protease inhibitors, but Epo failed to activate plasminogen and to mediate invasion into a human endothelial-like cell line. Swapping of ten amino acid residues at two surface loops of Pla and Epo introduced plasminogen activation capacity in Epo and inactivated the function in Pla. We also compared the structure of Pla and the modeled structure of Epo to analyze the structural variations that could rationalize the different proteolytic activities. Epo-expressing bacteria managed to invade human cells only after all extramembranous residues that differ between Pla and Epo and the first transmembrane β-strand had been changed. Conclusions We describe molecular adaptation of a protease from an environmental setting towards a virulence factor detrimental for humans. Our results stress the evolvability of bacterial β-barrel surface structures and the environment as a source of progenitor virulence molecules of human pathogens.

  14. Virulence factors and antibiotic susceptibility in enterococci isolated from oral mucosal and deep infections

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    Gunnar Dahlén

    2012-02-01

    Full Text Available This study evaluates the presence of virulence factors and antibiotic susceptibility among enterococcal isolates from oral mucosal and deep infections. Forty-three enterococcal strains from oral mucosal lesions and 18 from deep infections were isolated from 830 samples that were sent during 2 years to Oral Microbiology, University of Gothenburg, for analysis. The 61 strains were identified by 16S rDNA, and characterized by the presence of the virulence genes efa A (endocarditis gene, gel E (gelatinase gene, ace (collagen binding antigen gene, asa (aggregation substance gene, cyl A (cytolysin activator gene and esp (surface adhesin gene, tested for the production of bacteriocins and presence of plasmids. MIC determination was performed using the E-test method against the most commonly used antibiotics in dentistry, for example, penicillin V, amoxicillin and clindamycin. Vancomycin was included in order to detect vancomycin-resistant enterococci (VRE strains. Sixty strains were identified as Enterococcus faecalis and one as Enterococcus faecium. All the virulence genes were detected in more than 93.3% (efa A and esp of the E. faecalis strains, while the presence of phenotypic characteristics was much lower (gelatinase 10% and hemolysin 16.7%. Forty-six strains produced bacteriocins and one to six plasmids were detected in half of the isolates. Enterococcal strains from oral infections had a high virulence capacity, showed bacteriocin production and had numerous plasmids. They were generally susceptible to ampicillins but were resistant to clindamycin, commonly used in dentistry, and no VRE-strain was found.

  15. The Vibrio cholerae RND efflux systems impact virulence factor production and adaptive responses via periplasmic sensor proteins.

    Science.gov (United States)

    Bina, X Renee; Howard, Mondraya F; Taylor-Mulneix, Dawn L; Ante, Vanessa M; Kunkle, Dillon E; Bina, James E

    2018-01-01

    Resistance-nodulation-division (RND) efflux systems are ubiquitous transporters in Gram-negative bacteria that are essential for antibiotic resistance. The RND efflux systems also contribute to diverse phenotypes independent of antimicrobial resistance, but the mechanism by which they affect most of these phenotypes is unclear. This is the case in Vibrio cholerae where the RND systems function in antimicrobial resistance and virulence factor production. Herein, we investigated the linkage between RND efflux and V. cholerae virulence. RNA sequencing revealed that the loss of RND efflux affected the activation state of periplasmic sensing systems including the virulence regulator ToxR. Activation of ToxR in an RND null mutant resulted in ToxR-dependent transcription of the LysR-family regulator leuO. Increased leuO transcription resulted in the repression of the ToxR virulence regulon and attenuated virulence factor production. Consistent with this, leuO deletion restored virulence factor production in an RND-null mutant, but not its ability to colonize infant mice; suggesting that RND efflux was epistatic to virulence factor production for colonization. The periplasmic sensing domain of ToxR was required for the induction of leuO transcription in the RND null mutant, suggesting that ToxR responded to metabolites that accumulated in the periplasm. Our results suggest that ToxR represses virulence factor production in response to metabolites that are normally effluxed from the cell by the RND transporters. We propose that impaired RND efflux results in periplasmic metabolite accumulation, which then activates periplasmic sensors including ToxR and two-component regulatory systems to initiate the expression of adaptive responses.

  16. Functional and Structural Properties of a Novel Protein and Virulence Factor (sHIP) in Streptococcus pyogenes

    DEFF Research Database (Denmark)

    Wisniewska, Magdalena; Happonen, Lotta; Kahn, Fredrik

    2014-01-01

    Streptococcus pyogenes is a significant bacterial pathogen in the human population. The importance of virulence factors for the survival and colonization of S. pyogenes is well established, and many of these factors are exposed to the extracellular environment enabling bacterial interactions...... with the host. In the present study we quantitatively analyzed and compared S. pyogenes proteins in the growth medium of a strain that is virulent to mice, with a non-virulent strain. Particularly one of these proteins was present at significantly higher levels in stationary growth medium from the virulent......), and the name sHIP (streptococcal Histidine-rich glycoprotein Interacting Protein) is therefore proposed. HRG has antibacterial activity, and when challenged by HRG, sHIP was found to rescue S. pyogenes bacteria. This and the finding that patients with invasive S. pyogenes infection respond with antibody...

  17. Virulence factors of fluconazole-susceptible and fluconazole-resistant Candida albicans after antimicrobial photodynamic therapy.

    Science.gov (United States)

    Alves, Fernanda; de Oliveira Mima, Ewerton Garcia; Passador, Renata Caroline Polato; Bagnato, Vanderlei Salvador; Jorge, Janaína Habib; Pavarina, Ana Cláudia

    2017-05-01

    This study evaluated the effects of antimicrobial photodynamic therapy (aPDT) mediated by Photodithazine® (PDZ) and LED light on the virulence factors of fluconazole-susceptible (CaS) and fluconazole-resistant (CaR) Candida albicans. Standardized suspensions of strains were prepared (10 7 ), and after 48 h of biofilm formation, these strains were incubated with PDZ (100 mg/L) for 20 min and exposed to LED light (660 nm, 37.5 J/cm 2 ). Additional samples were treated with PDZ or light only, and the control consisted of biofilms that received no treatment. After aPDT, the cells were recovered and the virulence factors were evaluated. To analyze the capacity of adhesion, cells were recovered after aPDT and submitted to the adhesion process in the bottom of a 96-well plate. After this, metabolic activity tests (XTT assay) and cell viability (colony forming units per milliliter, CFU/mL) were applied. To evaluate the biofilm-forming ability after aPDT, the cells recovered were submitted to biofilm formation procedures, and the biofilm formed was evaluated by XTT, CFU/mL, and total biomass (crystal violet) tests. Lastly, the capacity for synthesizing protease and phospholipase enzymes after aPDT was evaluated by fluorimetric tests. Data were analyzed by two- or three-way ANOVA tests (p ≤ 0.05). It was verified that aPDT reduced the viability of both strains, fluconazole-susceptible and fluconazole-resistant C. albicans. It was also observed that the CaR strain had lower susceptibility to the aPDT when compared with the CaS strain. However, regarding the virulence factors evaluated, it was demonstrated that aPDT did not alter the adherence and biofilm formation ability and enzymatic production.

  18. The Role of the Multiple Banded Antigen of Ureaplasma parvum in Intra-Amniotic Infection: Major Virulence Factor or Decoy?

    OpenAIRE

    Dando, Samantha J.; Nitsos, Ilias; Kallapur, Suhas G.; Newnham, John P.; Polglase, Graeme R.; Pillow, J. Jane; Jobe, Alan H.; Timms, Peter; Knox, Christine L.

    2012-01-01

    The multiple banded antigen (MBA) is a predicted virulence factor of Ureaplasma species. Antigenic variation of the MBA is a potential mechanism by which ureaplasmas avoid immune recognition and cause chronic infections of the upper genital tract of pregnant women. We tested whether the MBA is involved in the pathogenesis of intra-amniotic infection and chorioamnionitis by injecting virulent or avirulent-derived ureaplasma clones (expressing single MBA variants) into the amniotic fluid of pre...

  19. Porphyromonas gingivalis virulence factors involved in subversion of leukocytes and microbial dysbiosis

    Science.gov (United States)

    Zenobia, Camille; Hajishengallis, George

    2015-01-01

    The oral bacterium Porphyromonas gingivalis has special nutrient requirements due to its asaccharolytic nature subsisting on small peptides cleaved from host proteins. Using proteases and other virulence factors, P. gingivalis thrives as a component of a polymicrobial community in nutritionally favorable inflammatory environments. In this regard, P. gingivalis has a number of strategies that subvert the host immune response in ways that promote its colonization and facilitate the outgrowth of the surrounding microbial community. The focus of this review is to discuss at the molecular level how P. gingivalis subverts leukocytes to create a favorable environment for a select community of bacteria that, in turn, adversely affects the periodontal tissues. PMID:25654623

  20. Functional metagenomics of spacecraft assembly cleanrooms: Presence of virulence factors associated with human pathogens.

    Directory of Open Access Journals (Sweden)

    Mina Bashir

    2016-09-01

    Full Text Available Strict planetary protection practices are implemented during spacecraft assembly to prevent inadvertent transfer of earth microorganisms to other planetary bodies. Therefore, spacecraft are assembled in cleanrooms, which undergo strict cleaning and decontamination procedures to reduce total microbial bioburden. We wanted to evaluate if these practices selectively favor survival and growth of hardy microorganisms, such as pathogens. Three geographically distinct cleanrooms were sampled during the assembly of three NASA spacecraft: The Lockheed Martin Aeronautics’ Multiple Testing Facility during DAWN, the Kennedy Space Center’s Payload Hazardous Servicing Facility (KSC-PHSF during Phoenix, and the Jet Propulsion Laboratory’s Spacecraft Assembly Facility during Mars Science Laboratory. Sample sets were collected from the KSC-PHSF cleanroom at three time points: before arrival of the Phoenix spacecraft, during the assembly and testing of the Phoenix spacecraft, and after removal of the spacecraft from the KSC-PHSF facility. All samples were subjected to metagenomic shotgun sequencing on an Illumina HiSeq 2500 platform. Strict decontamination procedures had a greater impact on microbial communities than sampling location Samples collected during spacecraft assembly were dominated by Acinetobacter spp. We found pathogens and potential virulence factors, which determine pathogenicity in all the samples tested during this study. Though the relative abundance of pathogens was lowest during the Phoenix assembly, potential virulence factors were higher during assembly compared to before and after assembly, indicating a survival advantage. Decreased phylogenetic and pathogenic diversity indicates that decontamination and preventative measures were effective against the majority of microorganisms and well implemented, however, pathogen abundance still increased over time. Four potential pathogens, Acinetobacter baumannii, Acinetobacter lwoffii

  1. The fimbrial protein FlfA from Gallibacterium anatis is a virulence factor and vaccine candidate

    DEFF Research Database (Denmark)

    Bager, Ragnhild Jørgensen; Nesta, Barbara; Pors, Susanne Elisabeth

    2013-01-01

    The Gram-negative bacterium Gallibacterium anatis is a major cause of salpingitis and peritonitis in egg-laying chickens, leading to decreased egg production worldwide. Widespread multidrug resistance largely prevents treatment of this organism using traditional antimicrobial agents, while antige......-independent vaccine candidate This is the first study describing a fimbrial subunit protein of G. anatis with a clear potential as a vaccine antigen....... antigenic diversity hampers disease prevention by classical vaccines. Thus, insight into its pathogenesis and knowledge about important virulence factors is urgently required. A key event during the colonization and invasion of mucosal surfaces is adherence, and recently, at least three F17-like fimbrial...

  2. Iron regulation of the major virulence factors in the AIDS-associated pathogen Cryptococcus neoformans.

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    Won Hee Jung

    2006-11-01

    Full Text Available Iron overload is known to exacerbate many infectious diseases, and conversely, iron withholding is an important defense strategy for mammalian hosts. Iron is a critical cue for Cryptococcus neoformans because the fungus senses iron to regulate elaboration of the polysaccharide capsule that is the major virulence factor during infection. Excess iron exacerbates experimental cryptococcosis and the prevalence of this disease in Sub-Saharan Africa has been associated with nutritional and genetic aspects of iron loading in the background of the HIV/AIDS epidemic. We demonstrate that the iron-responsive transcription factor Cir1 in Cr. neoformans controls the regulon of genes for iron acquisition such that cir1 mutants are "blind" to changes in external iron levels. Cir1 also controls the known major virulence factors of the pathogen including the capsule, the formation of the anti-oxidant melanin in the cell wall, and the ability to grow at host body temperature. Thus, the fungus is remarkably tuned to perceive iron as part of the disease process, as confirmed by the avirulence of the cir1 mutant; this characteristic of the pathogen may provide opportunities for antifungal treatment.

  3. Differential regulation of type I interferon and epidermal growth factor pathways by a human Respirovirus virulence factor.

    Directory of Open Access Journals (Sweden)

    Grégory Caignard

    2009-09-01

    Full Text Available A number of paramyxoviruses are responsible for acute respiratory infections in children, elderly and immuno-compromised individuals, resulting in airway inflammation and exacerbation of chronic diseases like asthma. To understand the molecular pathogenesis of these infections, we searched for cellular targets of the virulence protein C of human parainfluenza virus type 3 (hPIV3-C. We found that hPIV3-C interacts directly through its C-terminal domain with STAT1 and GRB2, whereas C proteins from measles or Nipah viruses failed to do so. Binding to STAT1 explains the previously reported capacity of hPIV3-C to block type I interferon signaling, but the interaction with GRB2 was unexpected. This adaptor protein bridges Epidermal Growth Factor (EGF receptor to MAPK/ERK pathway, a signaling cascade recently found to be involved in airway inflammatory response. We report that either hPIV3 infection or transient expression of hPIV3-C both increase cellular response to EGF, as assessed by Elk1 transactivation and phosphorylation levels of ERK1/2, 40S ribosomal subunit protein S6 and translation initiation factor 4E (eIF4E. Furthermore, inhibition of MAPK/ERK pathway with U0126 prevented viral protein expression in infected cells. Altogether, our data provide molecular basis to explain the role of hPIV3-C as a virulence factor and determinant of pathogenesis and demonstrate that Paramyxoviridae have evolved a single virulence factor to block type I interferon signaling and to boost simultaneous cellular response to growth factors.

  4. Mp1p Is a Virulence Factor in Talaromyces (Penicillium marneffei.

    Directory of Open Access Journals (Sweden)

    Patrick C Y Woo

    2016-08-01

    Full Text Available Talaromyces marneffei is an opportunistic dimorphic fungus prevalent in Southeast Asia. We previously demonstrated that Mp1p is an immunogenic surface and secretory mannoprotein of T. marneffei. Since Mp1p is a surface protein that can generate protective immunity, we hypothesized that Mp1p and/or its homologs are virulence factors.We examined the pathogenic roles of Mp1p and its homologs in a mouse model. All mice died 21 and 30 days after challenge with wild-type T. marneffei PM1 and MP1 complemented mutant respectively. None of the mice died 60 days after challenge with MP1 knockout mutant (P<0.0001. Seventy percent of mice died 60 days after challenge with MP1 knockdown mutant (P<0.0001. All mice died after challenge with MPLP1 to MPLP13 knockdown mutants, suggesting that only Mp1p plays a significant role in virulence. The mean fungal loads of PM1 and MP1 complemented mutant in the liver, lung, kidney and spleen were significantly higher than those of the MP1 knockout mutant. Similarly, the mean load of PM1 in the liver, lung and spleen were significantly higher than that of the MP1 knockdown mutant. Histopathological studies showed an abundance of yeast in the kidney, spleen, liver and lung with more marked hepatic and splenic necrosis in mice challenged with PM1 compared to MP1 knockout and MP1 knockdown mutants. Likewise, a higher abundance of yeast was observed in the liver and spleen of mice challenged with MP1 complemented mutant compared to MP1 knockout mutant. PM1 and MP1 complemented mutant survived significantly better than MP1 knockout mutant in macrophages at 48 hours (P<0.01 post-infection. The mean fungal counts of Pichia pastoris GS115-MP1 in the liver (P<0.001 and spleen (P<0.05 of mice were significantly higher than those of GS115 at 24 hours post-challenge.Mp1p is a key virulence factor of T. marneffei. Mp1p mediates virulence by improving the survival of T. marneffei in macrophages.

  5. Role of Uropathogenic Escherichia coli Virulence Factors in Development of Urinary Tract Infection and Kidney Damage

    Directory of Open Access Journals (Sweden)

    Justyna Bien

    2012-01-01

    Full Text Available Uropathogenic Escherichia coli (UPEC is a causative agent in the vast majority of urinary tract infections (UTIs, including cystitis and pyelonephritis, and infectious complications, which may result in acute renal failure in healthy individuals as well as in renal transplant patients. UPEC expresses a multitude of virulence factors to break the inertia of the mucosal barrier. In response to the breach by UPEC into the normally sterile urinary tract, host inflammatory responses are triggered leading to cytokine production, neutrophil influx, and the exfoliation of infected bladder epithelial cells. Several signaling pathways activated during UPEC infection, including the pathways known to activate the innate immune response, interact with calcium-dependent signaling pathways. Some UPEC isolates, however, might possess strategies to delay or suppress the activation of components of the innate host response in the urinary tract. Studies published in the recent past provide new information regarding how virulence factors of uropathogenic E. coli are involved in activation of the innate host response. Despite numerous host defense mechanisms, UPEC can persist within the urinary tract and may serve as a reservoir for recurrent infections and serious complications. Presentation of the molecular details of these events is essential for development of successful strategies for prevention of human UTIs and urological complications associated with UTIs.

  6. Virulence factors and strategies of Leptopilina spp.: selective responses in Drosophila hosts.

    Science.gov (United States)

    Lee, Mark J; Kalamarz, Marta E; Paddibhatla, Indira; Small, Chiyedza; Rajwani, Roma; Govind, Shubha

    2009-01-01

    To ensure survival, parasitic wasps of Drosophila have evolved strategies to optimize host development to their advantage. They also produce virulence factors that allow them to overcome or evade host defense. Wasp infection provokes cellular and humoral defense reactions, resulting in alteration in gene expression of the host. The activation of these reactions is controlled by conserved mechanisms shared by other invertebrate and vertebrate animals. Application of genomics and bioinformatics approaches is beginning to reveal comparative host gene expression changes after infection by different parasitic wasps. We analyze this comparison in the context of host physiology and immune cells, as well as the biology of the venom factors that wasps introduce into their hosts during oviposition. We compare virulence strategies of Leptopilina boulardi and L. heterotoma, in relation to genome-wide changes in gene expression in the fly hosts after infection. This analysis highlights fundamental differences in the changes that the host undergoes in its immune and general physiology in response to the two parasitic wasps. Such a comparative approach has the potential of revealing mechanisms governing the evolution of pathogenicity and how it impacts host range.

  7. Group A streptococcal puerperal sepsis: initial characterization of virulence factors in association with clinical parameters.

    Science.gov (United States)

    Byrne, Janice L B; Aagaard-Tillery, Kjersti M; Johnson, Jason L; Wright, Larry J; Silver, Robert M

    2009-10-01

    Group A beta-hemolytic streptococcus (GAS) is an uncommon but potentially fatal source of postpartum infection. Pathogenesis in invasive GAS infections has been linked to bacterial virulence factors. In this study, we sought to provide an initial description of potential virulence factors in association with puerperal morbidity by virtue of specific M-protein type antigens. Women with confirmed GAS puerperal infection in the Salt Lake City region were prospectively identified over a 6-year interval (1991-1997). From this cohort, GAS isolates were analyzed with respect to M-serotype and presence of genes encoding the Streptococcal Pyogenic Exotoxins A and B (SPE-A and SPE-B). Bacterial isolates from 18 subjects with GAS puerperal infection underwent M-serotyping and PCR-based genotyping for the speA and speB genes. Among these, 8/18 subjects manifest criteria of severe disease. All 18 isolate strains expressed speB; 6/18 isolates expressed speA. Of the M-serotypes, 8/8 severe disease isolates expressed M-types 1 (N=3) or 28 (N=5). Pulse-field gel electrophoresis did not indicate an outbreak strain among similar isolates. We conclude that in this initial characterization, morbidity among women with GAS puerperal infection is associated with M-types 1 and 28, but not speB genotype.

  8. Purification and Phytotoxic Analysis of Botrytis cinerea Virulence Factors: New Avenues for Crop Protection

    Directory of Open Access Journals (Sweden)

    Maria R. Davis

    2012-07-01

    Full Text Available Botrytis cinerea is a necrotrophic fungus infecting over 230 plant species worldwide. This highly adaptable pathogen can afflict agricultural products from seed to storage, causing significant economic losses and instability in the food supply. Small protein virulence factors secreted by B. cinerea during infection play an important role in initiation and spread of disease. BcSnod1 was found to be abundantly expressed upon exposure to media containing strawberry extract. From sequence similarity, BcSnod2 was also identified and both were recognized as members of the Ceratoplatanin family of small phytotoxic proteins. Recombinant BcSnod1 was shown to have a phytotoxic effect and play an important role in pathogenicity while the role of BcSnod2 remains less clear. Both bacterial and yeast production systems are reported, though the bacterial protein is less toxic and mostly unfolded relative to that made in yeast. Compared to BcSnod1, recombinant bacterial BcSnod2 shows similar, but delayed phytotoxicity on tomato leaves. Further studies of these critical virulence factors and their inhibition promise to provide new avenues for crop protection.

  9. Virulence factors in environmental and clinical Vibrio cholerae from endemic areas in Kenya

    Directory of Open Access Journals (Sweden)

    Racheal W. Kimani

    2014-04-01

    Full Text Available Background: Since 1971, Kenya has had repeated cholera outbreaks. However, the cause of seasonal epidemics of cholera is not fully understood and neither are the factors that drive epidemics, both in Kenya and globally.Objectives: The objectives of the study were to determine the environmental reservoirs of V. cholerae during an interepidemic period in Kenya and to characterise their virulence factors.Methods: One hundred (50 clinical, 50 environmental samples were tested for V. cholerae isolates using both simplex and multiplex polymerase chain reaction.Results: Both sediments and algae from fishing and landing bays yielded isolates of V. cholerae. Clinical strains were characterised along with the environmental strains for comparison. All clinical strains harboured ctxA, tcpA (El Tor, ompU, zot, ace, toxR, hylA (El Tor and tcpI genes. Prevalence for virulence genes in environmental strains was hylA (El Tor (10%, toxR (24%, zot (22%, ctxA (12%,tcpI (8%, hylA (26% and tcpA (12%.Conclusion: The study sites, including landing bays and beaches, contained environmental V. cholerae, suggesting that these may be reservoirs for frequent epidemics. Improved hygiene and fish-handling techniques will be important in reducing the persistence of reservoirs.

  10. Role of Uropathogenic Escherichia coli Virulence Factors in Development of Urinary Tract Infection and Kidney Damage

    Science.gov (United States)

    Bien, Justyna; Sokolova, Olga; Bozko, Przemyslaw

    2012-01-01

    Uropathogenic Escherichia coli (UPEC) is a causative agent in the vast majority of urinary tract infections (UTIs), including cystitis and pyelonephritis, and infectious complications, which may result in acute renal failure in healthy individuals as well as in renal transplant patients. UPEC expresses a multitude of virulence factors to break the inertia of the mucosal barrier. In response to the breach by UPEC into the normally sterile urinary tract, host inflammatory responses are triggered leading to cytokine production, neutrophil influx, and the exfoliation of infected bladder epithelial cells. Several signaling pathways activated during UPEC infection, including the pathways known to activate the innate immune response, interact with calcium-dependent signaling pathways. Some UPEC isolates, however, might possess strategies to delay or suppress the activation of components of the innate host response in the urinary tract. Studies published in the recent past provide new information regarding how virulence factors of uropathogenic E. coli are involved in activation of the innate host response. Despite numerous host defense mechanisms, UPEC can persist within the urinary tract and may serve as a reservoir for recurrent infections and serious complications. Presentation of the molecular details of these events is essential for development of successful strategies for prevention of human UTIs and urological complications associated with UTIs. PMID:22506110

  11. Relevance of Helicobacter pylori virulence factors for vaccine development Relevancia de los factores de virulencia de helicobacter pylori para el desarrollo de vacunas

    OpenAIRE

    Luz del Carmen Hernández-Hernández; Eduardo César Lazcano-Ponce; Yolanda López-Vidal; Germán Rubén Aguilar-Gutiérrez

    2009-01-01

    Helicobacter pylori infection increases the risk for a wide spectrum of clinical outcomes, ranging from peptic ulcer disease to gastric cancer. However, the infection induces gastric and duodenal ulceration or gastric cancer in only a minority of infected subjects because H. pylori strains are genetically diverse and express different virulence factors. Individuals infected with strains that express these virulence factors probably develop severe diseases such as gastric cancer. Nevertheless,...

  12. Comparative Genomics of Mycoplasma bovis Strains Reveals That Decreased Virulence with Increasing Passages Might Correlate with Potential Virulence-Related Factors

    Directory of Open Access Journals (Sweden)

    Muhammad A. Rasheed

    2017-05-01

    Full Text Available Mycoplasma bovis is an important cause of bovine respiratory disease worldwide. To understand its virulence mechanisms, we sequenced three attenuated M. bovis strains, P115, P150, and P180, which were passaged in vitro 115, 150, and 180 times, respectively, and exhibited progressively decreasing virulence. Comparative genomics was performed among the wild-type M. bovis HB0801 (P1 strain and the P115, P150, and P180 strains, and one 14.2-kb deleted region covering 14 genes was detected in the passaged strains. Additionally, 46 non-sense single-nucleotide polymorphisms and indels were detected, which confirmed that more passages result in more mutations. A subsequent collective bioinformatics analysis of paralogs, metabolic pathways, protein-protein interactions, secretory proteins, functionally conserved domains, and virulence-related factors identified 11 genes that likely contributed to the increased attenuation in the passaged strains. These genes encode ascorbate-specific phosphotransferase system enzyme IIB and IIA components, enolase, L-lactate dehydrogenase, pyruvate kinase, glycerol, and multiple sugar ATP-binding cassette transporters, ATP binding proteins, NADH dehydrogenase, phosphate acetyltransferase, transketolase, and a variable surface protein. Fifteen genes were shown to be enriched in 15 metabolic pathways, and they included the aforementioned genes encoding pyruvate kinase, transketolase, enolase, and L-lactate dehydrogenase. Hydrogen peroxide (H2O2 production in M. bovis strains representing seven passages from P1 to P180 decreased progressively with increasing numbers of passages and increased attenuation. However, eight mutants specific to eight individual genes within the 14.2-kb deleted region did not exhibit altered H2O2 production. These results enrich the M. bovis genomics database, and they increase our understanding of the mechanisms underlying M. bovis virulence.

  13. When ribosomes go bad: diseases of ribosome biogenesis.

    Science.gov (United States)

    Freed, Emily F; Bleichert, Franziska; Dutca, Laura M; Baserga, Susan J

    2010-03-01

    Ribosomes are vital for cell growth and survival. Until recently, it was believed that mutations in ribosomes or ribosome biogenesis factors would be lethal, due to the essential nature of these complexes. However, in the last few decades, a number of diseases of ribosome biogenesis have been discovered. It remains a challenge in the field to elucidate the molecular mechanisms underlying them.

  14. crRNA biogenesis

    NARCIS (Netherlands)

    Charpentier, E.; Oost, van der J.; White, M.

    2013-01-01

    Mature crRNAs are key elements in CRISPR-Cas defense against genome invaders. These short RNAs are composed of unique repeat/spacer sequences that guide the Cas protein(s) to the cognate invading nucleic acids for their destruction. The biogenesis of mature crRNAs involves highly precise processing

  15. Staphylococcal Panton-Valentine leucocidin as a major virulence factor associated to furuncles.

    Directory of Open Access Journals (Sweden)

    Lamine Baba-Moussa

    Full Text Available Panton-Valentine Leucocidin (PVL, one of the β-barrel pore-forming staphylococcal leucotoxins, is known to be associated to furuncles and some severe community pneumonia. However, it is still uncertain how many other virulence factors are also associated to furuncles and what the risk factors of furuncles are in immuno-compromised status of patients, especially the HIV (+ patients. In this paper, we use antigen immunoprecipitation and multiplex PCR approach to determine the presence of 19 toxins, 8 adhesion factors and the PFGE profiles associated to furuncles in three independent patient study groups of S. aureus (SA isolates collected from the Cayenne General Hospital (French Guiana. The patient groups were made of: 16 isolates from HIV (- patients, 9 from HIV (+ patients suffering from furuncles, and 30 control isolates from patients with diverse secondary infected dermatitis. Our data reveals that the majority (96% of SA strains isolated from HIV patient-derived furuncles significantly produced PVL (p<10(-7, whereas only 10% of SA strains produced this toxin in secondary infected dermatosis. A high prevalence of LukE-LukD-producing isolates (56 to 78% was recorded in patient groups. Genes encoding clumping factor B, collagen- and laminin-binding proteins (clfB, cna, lbp, respectively were markedly frequent (30 to 55%, without being associated to a specific group. Pulse field gel electrophoresis evidenced 24 overall pulsotypes, whereas the 25 PVL-producing isolates were distributed into 15 non clonal fingerprints. These pulsotypes were not specific PVL-producing isolates. PVL appears to be the major virulence factor associated to furuncles in Europe and in South America regardless of the immune status of the HIV patients.

  16. Antimicrobial activity, antibiotic susceptibility and virulence factors of Lactic Acid Bacteria of aquatic origin intended for use as probiotics in aquaculture

    National Research Council Canada - National Science Library

    Muñoz-Atienza, Estefanía; Gómez-Sala, Beatriz; Araújo, Carlos; Campanero, Cristina; del Campo, Rosa; Hernández, Pablo E; Herranz, Carmen; Cintas, Luis M

    2013-01-01

    .... The objective of this work was to investigate the antimicrobial/bacteriocin activity against fish pathogens, the antibiotic susceptibility, and the prevalence of virulence factors and detrimental...

  17. The Role of Virulence Factors in the Pathogenicity of Colletotrichum sp.

    Science.gov (United States)

    Villa-Rivera, Maria G; Conejo-Saucedo, Ulises; Lara-Marquez, Alicia; Cano-Camacho, Horacio; Lopez-Romero, Everardo; Zavala-Paramo, Maria G

    2017-01-01

    The Colletotrichum genus has been considered as one of the top 10 fungal pathogens in molecular plant pathology based on their scientific and agrobiological importance. Although the genus contains species with different lifestyles, most of the Colletotrichum sp. are known by their hemibiotrophic strategy of infection/invasion causing anthracnose disease in many economically important crops. Hemibiotrophy includes two sequential stages of infection, biotrophy and necrotrophy, in a series of steps that involve the participation of different virulence factors. In this review, we present the current status of the knowledge of such factors reported in this genus and a list of related genes identified in Colletotrichum sp. genomes. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  18. Tissue tropisms in group A Streptococcus: what virulence factors distinguish pharyngitis from impetigo strains?

    Science.gov (United States)

    Bessen, Debra E

    2016-06-01

    Group A streptococci (GAS) are a common cause of pharyngitis and impetigo, and distinct throat strains and skin strains have been long recognized. This review aims to describe recent advances in molecular differences between throat and skin strains, and the pathogenic mechanisms used by virulence factors that may distinguish between these two groups. Recent findings include a new typing scheme for GAS strains based on sequence clusters of genes encoding the entire surface-exposed portion of M protein; correlations between emm-based typing schemes, clinical disease and surface adhesins; covalent bond formation mediated by GAS pili and other adhesins in binding to host ligands; a key role for superantigens in oropharyngeal infection via binding major histocompatibility complex class II antigen; and migration of GAS-specific Th17 cells from the upper respiratory tract to the brain, which may be relevant to autoimmune sequelae. The gap between molecular markers of disease (correlation) and virulence mechanisms (causation) in the establishment of tissue tropisms for GAS infection currently remains wide, but the gap also continues to narrow. Whole genome sequencing combined with mutant construction and improvements in animal models for oropharyngeal infection by GAS may help pave the way for new discoveries.

  19. Excess labile carbon promotes the expression of virulence factors in coral reef bacterioplankton

    KAUST Repository

    Cardenas, Anny

    2017-09-12

    Coastal pollution and algal cover are increasing on many coral reefs, resulting in higher dissolved organic carbon (DOC) concentrations. High DOC concentrations strongly affect microbial activity in reef waters and select for copiotrophic, often potentially virulent microbial populations. High DOC concentrations on coral reefs are also hypothesized to be a determinant for switching microbial lifestyles from commensal to pathogenic, thereby contributing to coral reef degradation, but evidence is missing. In this study, we conducted ex situ incubations to assess gene expression of planktonic microbial populations under elevated concentrations of naturally abundant monosaccharides (glucose, galactose, mannose, and xylose) in algal exudates and sewage inflows. We assembled 27 near-complete (>70%) microbial genomes through metagenomic sequencing and determined associated expression patterns through metatranscriptomic sequencing. Differential gene expression analysis revealed a shift in the central carbohydrate metabolism and the induction of metalloproteases, siderophores, and toxins in Alteromonas, Erythrobacter, Oceanicola, and Alcanivorax populations. Sugar-specific induction of virulence factors suggests a mechanistic link for the switch from a commensal to a pathogenic lifestyle, particularly relevant during increased algal cover and human-derived pollution on coral reefs. Although an explicit test remains to be performed, our data support the hypothesis that increased availability of specific sugars changes net microbial community activity in ways that increase the emergence and abundance of opportunistic pathogens, potentially contributing to coral reef degradation.

  20. The serine protease Pic as a virulence factor of atypical enteropathogenic Escherichia coli.

    Science.gov (United States)

    Abreu, Afonso G; Abe, Cecilia M; Nunes, Kamila O; Moraes, Claudia T P; Chavez-Dueñas, Lucia; Navarro-Garcia, Fernando; Barbosa, Angela S; Piazza, Roxane M F; Elias, Waldir P

    2016-01-01

    Autotransporter proteins (AT) are associated with bacterial virulence attributes. Originally identified in enteroaggregative Escherichia coli (EAEC), Shigella flexneri 2a and uropathogenic E. coli, the serine protease Pic is one of these AT. We have previously detected one atypical enteropathogenic E. coli strain (BA589) carrying the pic gene. In the present study, we characterized the biological activities of Pic produced by BA589 both in vitro and in vivo. Contrarily to other Pic-producers bacteria, pic in BA589 is located on a high molecular weight plasmid. PicBA589 was able to agglutinate rabbit erythrocytes, cleave mucin and degrade complement system molecules. BA589 was able to colonize mice intestines, and an intense mucus production was observed. The BA589Δpic mutant lost the capacity to colonize as well as the above-mentioned in vitro activities. Thus, Pic represents an additional virulence factor in aEPEC strain BA589, associated with adherence, colonization and evasion from the innate immune system.

  1. Virulence factors and clinical patterns of hypermucoviscous Klebsiella pneumoniae isolated from urine.

    Science.gov (United States)

    Kim, Youn Jeong; Kim, Sang Il; Kim, Yang Ree; Wie, Seong Heon; Lee, Hae Kyung; Kim, Soo-Young; Park, Yeon-Joon

    2017-03-01

    Klebsiella pneumoniae with hypermucoviscosity (HM) phenotype is generally more virulent than HM-negative strains. The aim of this study was to investigate the prevalence of HM phenotype among urinary isolates and to compare the virulence factors, antimicrobial susceptibility patterns and clinical characteristics of HM-positive and -negative K. pneumoniae isolated from urine of hospitalized patients. From June to October 2013, a total of 81 non-repetitive K. pneumoniae strains were isolated from urine. HM phenotype was determined by a string test. The K1 and K2 genotypes, the allS, kfu, rmpA, rmpA2 and wabG, aerobactin gene were detected by polymerase chain reaction. Of the 81 K. pneumoniae isolates, 12.3% produced a positive string test. The aerobactin (80.0%[8/10] vs. 15.5%[11/71], p = .0001), allS (40.0%[4/10] vs. 9.9%[7/71], p = .009), rmpA (70.0%[7/10] vs. 14.1%[10/71], p = .0001) and rmpA2 (60.0%[6/10] vs. 16.9%[12/71], p = .002) genes were more prevalent in HM positive than in HM negative strains. The K1 (20.0%[2/10) vs. 8.5%[6/71

  2. Effects of Rhodomyrtus tomentosa extract on virulence factors of Candida albicans and human neutrophil function.

    Science.gov (United States)

    Hmoteh, Jutharat; Musthafa, Khadar Syed; Voravuthikunchai, Supayang Piyawan

    2017-12-10

    Candida albicans has become a major problem of oral candidiasis due to increase in antibiotic resistance. Rhodomyrtus tomentosa, a medicinal plant possessing several phytochemical constituents, has been considered as a potential source of antimicrobial and immunomodulatory agents. The aim of this study was to investigate anti-virulence and immunostimulatory activity of R. tomentosa ethanolic leaf extract against C. albicans. The effects of the extract on C. albicans were assessed on germ tube production, adherence of the organisms to surfaces, and biofilm. In addition, the effects of the extract on phagocytosis and killing activity of neutrophils against the pathogen were investigated. Suppression of germ tube production following 30 min exposure to the extract at 256 μg/mL was significantly increased in comparison with that of the unexposed cells (p extract at 512-1024 μg/mL significantly reduced biofilm forming ability of the organisms up to 42.31-64.58% (p extract at 256 μg/mL was observed (p extract at 50 μg/mL significantly enhanced phagocytosis and killing activity of neutrophils against the organism, compared with the control (p extract displayed a dual mode of action, inhibiting virulence factors of C. albicans and enhancing neutrophil functions. Further pharmaceutical development of the extract might be useful as an alternative therapeutic agent against oral candidiasis. Copyright © 2017. Published by Elsevier Ltd.

  3. Acceleration of epithelial cell syndecan-1 shedding by anthrax hemolytic virulence factors

    Directory of Open Access Journals (Sweden)

    Chandhoke Vikas

    2006-02-01

    Full Text Available Abstract Background It has been recently reported that major pathogens Staphylococcus aureus and Pseudomonas aeruginosa accelerate a normal process of cell surface syndecan-1 (Synd1 ectodomain shedding as a mechanism of host damage due to the production of shedding-inducing virulence factors. We tested if acceleration of Synd1 shedding takes place in vitro upon treatment of epithelial cells with B. anthracis hemolysins, as well as in vivo during anthrax infection in mice. Results The isolated anthrax hemolytic proteins AnlB (sphingomyelinase and AnlO (cholesterol-binding pore-forming factor, as well as ClnA (B. cereus homolog of B. anthracis phosphatidyl choline-preferring phospholipase C cause accelerated shedding of Synd1 and E-cadherin from epithelial cells and compromise epithelial barrier integrity within a few hours. In comparison with hemolysins in a similar range of concentrations, anthrax lethal toxin (LT also accelerates shedding albeit at slower rate. Individual components of LT, lethal factor and protective antigen are inactive with regard to shedding. Inhibition experiments favor a hypothesis that activities of tested bacterial shedding inducers converge on the stimulation of cytoplasmic tyrosine kinases of the Syk family, ultimately leading to activation of cellular sheddase. Both LT and AnlO modulate ERK1/2 and p38 MAPK signaling pathways, while JNK pathway seems to be irrelevant to accelerated shedding. Accelerated shedding of Synd1 also takes place in DBA/2 mice challenged with Bacillus anthracis (Sterne spores. Elevated levels of shed ectodomain are readily detectable in circulation after 24 h. Conclusion The concerted acceleration of shedding by several virulence factors could represent a new pathogenic mechanism contributing to disruption of epithelial or endothelial integrity, hemorrhage, edema and abnormal cell signaling during anthrax infection.

  4. RpoN Regulates Virulence Factors of Pseudomonas aeruginosa via Modulating the PqsR Quorum Sensing Regulator

    Directory of Open Access Journals (Sweden)

    Zhao Cai

    2015-11-01

    Full Text Available The alternative sigma factor RpoN regulates many cell functions, such as motility, quorum sensing, and virulence in the opportunistic pathogen Pseudomonas aeruginosa (P. aeruginosa. P. aeruginosa often evolves rpoN-negative variants during the chronic infection in cystic fibrosis patients. It is unclear how RpoN interacts with other regulatory mechanisms to control virulence of P. aeruginosa. In this study, we show that RpoN modulates the function of PqsR, a quorum sensing receptor regulating production of virulence factors including the phenazine pyocyanin. The ∆rpoN mutant is able to synthesize 4-quinolone signal molecule HHQ but unable to activate PqsR and Pseudomonas quinolone signal (pqs quorum sensing. The ∆rpoN mutant produces minimal level of pyocyanin and is unable to produce the anti-staphylococcal agents. Providing pqsR in trans in the ∆rpoN mutant restores its pqs quorum sensing and virulence factor production to the wild-type level. Our study provides evidence that RpoN has a regulatory effect on P. aeruginosa virulence through modulating the function of the PqsR quorum sensing regulator.

  5. HCF153, a novel nuclear-encoded factor necessary during a post-translational step in biogenesis of the cytochrome bf complex.

    Science.gov (United States)

    Lennartz, Katja; Bossmann, Sabine; Westhoff, Peter; Bechtold, Nicole; Meierhoff, Karin

    2006-01-01

    We have isolated the nuclear photosynthetic mutant hcf153 which shows reduced accumulation of the cytochrome b(6)f complex. The levels and processing patterns of the RNAs encoding the cytochrome b(6)f subunits are unaltered in the mutant. In vivo protein labeling experiments and analysis of polysome association revealed normal synthesis of the large chloroplast-encoded cytochrome b(6)f subunits. The mutation resulted from a T-DNA insertion and the affected nuclear gene was cloned. HCF153 encodes a 15 kDa protein containing a chloroplast transit peptide. Sequence similarity searches revealed that the protein is restricted to higher plants. A HCF153-Protein A fusion construct introduced into hcf153 mutant plants was able to substitute the function of the wild-type protein. Fractionation of intact chloroplasts from these transgenic plants suggests that most or all of the fusion protein is tightly associated with the thylakoid membrane. Our data show that the identified factor is a novel protein that could be involved in a post-translational step during biogenesis of the cytochrome b(6)f complex. It is also possible that HCF153 is necessary for translation of one of the very small subunits of the cytochrome b(6)f complex.

  6. Staphylococcus aureus clonal dynamics and virulence factors in children with atopic dermatitis

    DEFF Research Database (Denmark)

    Lomholt, Hans Bredsted; Andersen, KE; Kilian, Mogens

    2005-01-01

    A prospective cohort study was undertaken to determine the clonal dynamics of Staphylococcus aureus colonization and infection during 1 y in children with atopic dermatitis, and to correlate specific clones, accessory gene regulator (agr) groups, and production of virulence factors with eczema...... activity. Eleven children were examined every 6 wk with swaps taken from active eczema, anterior nose, axillae and perineum, and scoring of eczema activity by severity scoring of atopic dermatitis (SCORAD). Individual S. aureus clonal types were identified and examined for production of superantigens...... SCORAD value. In 11 of 12 cases with two different clones co-colonizing a child the clones belonged to the same agr group. In conclusion, this limited group of children with atopic dermatitis showed highly variable colonization patterns of S. aureus, and communication between strains by use of agr...

  7. Cellular Effects of Pyocyanin, a Secreted Virulence Factor of Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Susan Hall

    2016-08-01

    Full Text Available Pyocyanin has recently emerged as an important virulence factor produced by Pseudomonas aeruginosa. The redox-active tricyclic zwitterion has been shown to have a number of potential effects on various organ systems in vitro, including the respiratory, cardiovascular, urological, and central nervous systems. It has been shown that a large number of the effects to these systems are via the formation of reactive oxygen species. The limitations of studies are, to date, focused on the localized effect of the release of pyocyanin (PCN. It has been postulated that, given its chemical properties, PCN is able to readily cross biological membranes, however studies have yet to be undertaken to evaluate this effect. This review highlights the possible manifestations of PCN exposure; however, most studies to date are in vitro. Further high quality in vivo studies are needed to fully assess the physiological manifestations of PCN exposure on the various body systems.

  8. Cellular Effects of Pyocyanin, a Secreted Virulence Factor of Pseudomonas aeruginosa.

    Science.gov (United States)

    Hall, Susan; McDermott, Catherine; Anoopkumar-Dukie, Shailendra; McFarland, Amelia J; Forbes, Amanda; Perkins, Anthony V; Davey, Andrew K; Chess-Williams, Russ; Kiefel, Milton J; Arora, Devinder; Grant, Gary D

    2016-08-09

    Pyocyanin has recently emerged as an important virulence factor produced by Pseudomonas aeruginosa. The redox-active tricyclic zwitterion has been shown to have a number of potential effects on various organ systems in vitro, including the respiratory, cardiovascular, urological, and central nervous systems. It has been shown that a large number of the effects to these systems are via the formation of reactive oxygen species. The limitations of studies are, to date, focused on the localized effect of the release of pyocyanin (PCN). It has been postulated that, given its chemical properties, PCN is able to readily cross biological membranes, however studies have yet to be undertaken to evaluate this effect. This review highlights the possible manifestations of PCN exposure; however, most studies to date are in vitro. Further high quality in vivo studies are needed to fully assess the physiological manifestations of PCN exposure on the various body systems.

  9. Phenazine virulence factor binding to extracellular DNA is important for Pseudomonas aeruginosa biofilm formation

    Science.gov (United States)

    Das, Theerthankar; Kutty, Samuel K.; Tavallaie, Roya; Ibugo, Amaye I.; Panchompoo, Janjira; Sehar, Shama; Aldous, Leigh; Yeung, Amanda W. S.; Thomas, Shane R.; Kumar, Naresh; Gooding, J. Justin; Manefield, Mike

    2015-01-01

    Bacterial resistance to conventional antibiotics necessitates the identification of novel leads for infection control. Interference with extracellular phenomena, such as quorum sensing, extracellular DNA integrity and redox active metabolite release, represents a new frontier to control human pathogens such as Pseudomonas aeruginosa and hence reduce mortality. Here we reveal that the extracellular redox active virulence factor pyocyanin produced by P. aeruginosa binds directly to the deoxyribose-phosphate backbone of DNA and intercalates with DNA nitrogenous base pair regions. Binding results in local perturbations of the DNA double helix structure and enhanced electron transfer along the nucleic acid polymer. Pyocyanin binding to DNA also increases DNA solution viscosity. In contrast, antioxidants interacting with DNA and pyocyanin decrease DNA solution viscosity. Biofilms deficient in pyocyanin production and biofilms lacking extracellular DNA show similar architecture indicating the interaction is important in P. aeruginosa biofilm formation. PMID:25669133

  10. Low distribution of genes encoding virulence factors in Shigella flexneri serotypes 1b clinical isolates from eastern Chinese populations.

    Science.gov (United States)

    Fan, Wenting; Qian, Huimin; Shang, Wenkang; Ying, Chen; Zhang, Xuedi; Cheng, Song; Gu, Bing; Ma, Ping

    2017-01-01

    The ability of Shigella to invade, colonize, and eventually kill host cells is influenced by many virulence factors. However, there is no analysis of related genes in Jiangsu Province of China so far. Shigella flexneri was collected from 13 cities of Jiangsu Province through the provincial Centers for Disease Control (CDC) for analysis of distribution of major virulence genes (ipaH, ipaBCD, ial, virF, virB, sigA, set1A, sepA, sat, pic, set1B and sen) detected by PCR technology. A total of 545 isolates received were confirmed as S. flexneri which belongs to 11 serotypes of S. flexneri, among which serotype 2a was the most predominant (n = 223, 40.9%). All isolates were positive for ipaH gene, followed by sat (94.1%), sigA (78.9%), set1B (78.0%), pic (77.6%), set1A (74.5%), virF (64.8%), sepA (63.5%), sen (56.9%), ipaBCD (50.5%), ial (47.0%) and virB (47.0%). The presence of virulence genes in different serotypes was distinct. The existence of virulence genes of serotype 1b was generally lower than other serotype-the positive rate for virulence genes was between 0.0 and 14.1% except for ipaH and sat. In addition, virulence genes also fluctuated in different regions and at different times in Jiangsu province. The result of analysis on the relationship between virulence genes of S. flexneri showed that the existence of virulence genes of Shigella could be well represented by multiplex PCR combination ipaH + ial + set1A, which had a high clinical value. The present study was designed to explore the prevalence of 12 S. flexneri-associated virulence genes. The data showed high diversity of virulence genes with regard to periods, regions and serotypes in Jiangsu Province of China.

  11. Virulence factors and genetic variability of Staphylococcus aureus strains isolated from raw sheep's milk cheese.

    Science.gov (United States)

    Spanu, Vincenzo; Spanu, Carlo; Virdis, Salvatore; Cossu, Francesca; Scarano, Christian; De Santis, Enrico Pietro Luigi

    2012-02-01

    Contamination of dairy products with Staphylococcus aureus can be of animal or human origin. The host pathogen relationship is an important factor determining genetic polymorphism of the strains and their potential virulence. The aim of the present study was to carry out an extensive characterization of virulence factors and to study the genetic variability of S. aureus strains isolated from raw ewe's milk cheese. A total of 100 S. aureus strains isolated from cheese samples produced in 10 artisan cheese factories were analyzed for the presence of enterotoxins (sea-see) and enterotoxins-like genes (seh, sek, sel, sem, seo, sep), leukocidins, exfoliatins, haemolysins, toxic shock syndrome toxin 1 (TSST-1) and the accessory gene regulator alleles (agr). Strains were also typed using pulsed-field gel electrophoresis (PFGE). AMOVA analysis carried out on PFGE and PCR data showed that the major component explaining genetic distance between strains was the dairy of origin. Of the total isolates 81% had a pathogenicity profile ascribable to "animal" biovar while 16% could be related to "human" biovar. The biovar allowed to estimate the most likely origin of the contamination. Minimum inhibitory concentrations (MICs) of nine antimicrobial agents and the presence of the corresponding genes coding for antibiotic resistance was also investigated. 18 strains carrying blaZ gene showed resistance to ampicillin and penicillin and 6 strains carrying tetM gene were resistant to tetracycline. The presence of mecA gene and methicillin resistance, typical of strains of human origin, was never detected. The results obtained in the present study confirm that S. aureus contamination in artisan cheese production is mainly of animal origin. Copyright © 2011. Published by Elsevier B.V.

  12. Subinhibitory concentrations of perilla oil affect the expression of secreted virulence factor genes in Staphylococcus aureus.

    Directory of Open Access Journals (Sweden)

    Jiazhang Qiu

    Full Text Available BACKGROUND: The pathogenicity of staphylococcus aureus is dependent largely upon its ability to secrete a number of virulence factors, therefore, anti-virulence strategy to combat S. aureus-mediated infections is now gaining great interest. It is widely recognized that some plant essential oils could affect the production of staphylococcal exotoxins when used at subinhibitory concentrations. Perilla [Perilla frutescens (L. Britton], a natural medicine found in eastern Asia, is primarily used as both a medicinal and culinary herb. Its essential oil (perilla oil has been previously demonstrated to be active against S. aureus. However, there are no data on the influence of perilla oil on the production of S. aureus exotoxins. METHODOLOGY/PRINCIPAL FINDINGS: A broth microdilution method was used to determine the minimum inhibitory concentrations (MICs of perilla oil against S. aureus strains. Hemolysis, tumour necrosis factor (TNF release, Western blot, and real-time RT-PCR assays were performed to evaluate the effects of subinhibitory concentrations of perilla oil on exotoxins production in S. aureus. The data presented here show that perilla oil dose-dependently decreased the production of α-toxin, enterotoxins A and B (the major staphylococcal enterotoxins, and toxic shock syndrome toxin 1 (TSST-1 in both methicillin-sensitive S. aureus (MSSA and methicillin-resistant S. aureus (MRSA. CONCLUSIONS/SIGNIFICANCE: The production of α-toxin, SEA, SEB, and TSST-1 in S. aureus was decreased by perilla oil. These data suggest that perilla oil may be useful for the treatment of S. aureus infections when used in combination with β-lactam antibiotics, which can increase exotoxins production by S. aureus at subinhibitory concentrations. Furthermore, perilla oil could be rationally applied in food systems as a novel food preservative both to inhibit the growth of S. aureus and to repress the production of exotoxins, particularly staphylococcal enterotoxins.

  13. Virulence factors genes of Staphylococcus spp. isolated from caprine subclinical mastitis.

    Science.gov (United States)

    Salaberry, Sandra Renata Sampaio; Saidenberg, André Becker Simões; Zuniga, Eveline; Melville, Priscilla Anne; Santos, Franklin Gerônimo Bispo; Guimarães, Ednaldo Carvalho; Gregori, Fábio; Benites, Nilson Roberti

    2015-08-01

    The aim of this study was to investigate genes involved in adhesion expression, biofilm formation, and enterotoxin production in isolates of Staphylococcus spp. from goats with subclinical mastitis and associate these results with the staphylococcal species. One hundred and twenty-four isolates were identified and polymerase chain reaction (PCR) was performed to detect the following genes: cna, ebpS, eno, fib, fnbA, fnbB, bap, sea, seb, sec, sed and see. The most commonly Staphylococcus species included S. epidermidis, S. lugdunensis, S. chromogenes, S. capitis ss capitis and S. intermedius. With the exception of fnbB, the genes were detected in different frequencies of occurrence in 86.3% of the Staphylococcus spp. isolates. Eno (73.2%) and bap (94.8%) were more frequently detected in coagulase-negative staphylococci (CNS); ebpS (76%), fib (90.9%) and fnbA (87%) were the most frequent genes in coagulase-positive staphylococci (CPS). Regarding enterotoxins, genes sed (28.2%) and see (24.2%) had a higher frequency of occurrence; sec gene was more frequently detected in CPS (58.8%). There was no association between the presence of the genes and the Staphylococcus species. Different virulence factors genes can be detected in caprine subclinical mastitis caused by CNS and CPS. The knowledge of the occurrence of these virulence factors is important for the development of effective control and prevention measures of subclinical mastitis caused by CNS and CPS in goats. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Phosphatidylserine externalization and procoagulant activation of erythrocytes induced by Pseudomonas aeruginosa virulence factor pyocyanin.

    Science.gov (United States)

    Qadri, Syed M; Donkor, David A; Bhakta, Varsha; Eltringham-Smith, Louise J; Dwivedi, Dhruva J; Moore, Jane C; Pepler, Laura; Ivetic, Nikola; Nazi, Ishac; Fox-Robichaud, Alison E; Liaw, Patricia C; Sheffield, William P

    2016-04-01

    The opportunistic pathogen Pseudomonas aeruginosa causes a wide range of infections in multiple hosts by releasing an arsenal of virulence factors such as pyocyanin. Despite numerous reports on the pleiotropic cellular targets of pyocyanin toxicity in vivo, its impact on erythrocytes remains elusive. Erythrocytes undergo an apoptosis-like cell death called eryptosis which is characterized by cell shrinkage and phosphatidylserine (PS) externalization; this process confers a procoagulant phenotype on erythrocytes as well as fosters their phagocytosis and subsequent clearance from the circulation. Herein, we demonstrate that P. aeruginosa pyocyanin-elicited PS exposure and cell shrinkage in erythrocyte while preserving the membrane integrity. Mechanistically, exposure of erythrocytes to pyocyanin showed increased cytosolic Ca(2+) activity as well as Ca(2+) -dependent proteolytic processing of μ-calpain. Pyocyanin further up-regulated erythrocyte ceramide abundance and triggered the production of reactive oxygen species. Pyocyanin-induced increased PS externalization in erythrocytes translated into enhanced prothrombin activation and fibrin generation in plasma. As judged by carboxyfluorescein succinimidyl-ester labelling, pyocyanin-treated erythrocytes were cleared faster from the murine circulation as compared to untreated erythrocytes. Furthermore, erythrocytes incubated in plasma from patients with P. aeruginosa sepsis showed increased PS exposure as compared to erythrocytes incubated in plasma from healthy donors. In conclusion, the present study discloses the eryptosis-inducing effect of the virulence factor pyocyanin, thereby shedding light on a potentially important mechanism in the systemic complications of P. aeruginosa infection. © 2016 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

  15. Effects of Pseudomonas aeruginosa virulence factor pyocyanin on human urothelial cell function and viability.

    Science.gov (United States)

    McDermott, Catherine; Chess-Williams, Russ; Grant, Gary D; Perkins, Anthony V; McFarland, Amelia J; Davey, Andrew K; Anoopkumar-Dukie, Shailendra

    2012-03-01

    We determined the effects of Pseudomonas aeruginosa virulence factor pyocyanin on human urothelial cell viability and function in vitro. RT4 urothelial cells were treated with pyocyanin (1 to 100 μM) for 24 hours. After exposure the treatment effects were measured according to certain end points, including changes in urothelial cell viability, reactive oxygen species formation, caspase-3 activity, basal and stimulated adenosine triphosphate release, SA-β-gal activity and detection of acidic vesicular organelles. The 24-hour pyocyanin treatment resulted in a concentration dependent decrease in cell viability at concentrations of 25 μM or greater, and increases in reactive oxygen species formation and caspase-3 activity at 25 μM or greater. Basal adenosine triphosphate release was significantly decreased at all tested pyocyanin concentrations while stimulated adenosine triphosphate release was significantly inhibited at pyocyanin concentrations of 12.5 μM or greater with no significant stimulated release at 100 μM. Pyocyanin treated RT4 cells showed morphological characteristics associated with cellular senescence, including SA-β-gal expression. This effect was not evident at 100 μM pyocyanin and may have been due to apoptotic cell death, as indicated by increased caspase-3 activity. An increase in acridine orange stained vesicular-like organelles was observed in RT4 urothelial cells after pyocyanin treatment. Exposure to pyocyanin alters urothelial cell viability, reactive oxygen species production and caspase-3 activity. Treatment also results in cellular senescence, which may affect the ability of urothelium to repair during infection. The virulence factor depressed stimulated adenosine triphosphate release, which to our knowledge is a novel finding with implications for awareness of bladder filling in patients with P. aeruginosa urinary tract infection. Copyright © 2012 American Urological Association Education and Research, Inc. Published by Elsevier

  16. The ability of virulence factor expression by Pseudomonas aeruginosa to predict clinical disease in hospitalized patients.

    Directory of Open Access Journals (Sweden)

    Michel Ledizet

    Full Text Available Pseudomonas aeruginosa is an opportunistic pathogen that frequently causes hospital acquired colonization and infection. Accurate identification of host and bacterial factors associated with infection could aid treatment decisions for patients with P. aeruginosa cultured from clinical sites.We identified a prospective cohort of 248 hospitalized patients with positive P. aeruginosa cultures. Clinical data were analyzed to determine whether an individual met predefined criteria for infection versus colonization. P. aeruginosa isolates were tested for the expression of multiple phenotypes previously associated with virulence in animal models and humans. Logistic regression models were constructed to determine the degree of association between host and bacterial factors with P. aeruginosa infection of the bloodstream, lung, soft tissue and urinary tract.One host factor (i.e. diabetes mellitus, and one bacterial factor, a Type 3 secretion system positive phenotype, were significantly associated with P. aeruginosa infection in our cohort. Subgroup analysis of patients with P. aeruginosa isolated from the urinary tract revealed that the presence of a urinary tract catheter or stent was an additional factor for P. aeruginosa infection.Among hospitalized patients with culture-documented P. aeruginosa, infection is more likely to be present in those with diabetes mellitus and those harboring a Type 3 secretion positive bacterial strain.

  17. Dynamics of Escherichia coli Virulence Factors in Dairy Herds and Farm Environments in a Longitudinal Study in the United States

    Science.gov (United States)

    Lambertini, Elisabetta; Karns, Jeffrey S.; Van Kessel, Jo Ann S.; Cao, Huilin; Schukken, Ynte H.; Wolfgang, David R.; Smith, Julia M.

    2015-01-01

    Pathogenic Escherichia coli or its associated virulence factors have been frequently detected in dairy cow manure, milk, and dairy farm environments. However, it is unclear what the long-term dynamics of E. coli virulence factors are and which farm compartments act as reservoirs. This study assessed the occurrence and dynamics of four E. coli virulence factors (eae, stx1, stx2, and the gamma allele of the tir gene [γ-tir]) on three U.S. dairy farms. Fecal, manure, water, feed, milk, and milk filter samples were collected from 2004 to 2012. Virulence factors were measured by postenrichment quantitative PCR (qPCR). All factors were detected in most compartments on all farms. Fecal and manure samples showed the highest prevalence, up to 53% for stx and 21% for γ-tir in fecal samples and up to 84% for stx and 44% for γ-tir in manure. Prevalence was low in milk (up to 1.9% for stx and 0.7% for γ-tir). However, 35% of milk filters were positive for stx and 20% were positive for γ-tir. All factors were detected in feed and water. Factor prevalence and levels, expressed as qPCR cycle threshold categories, fluctuated significantly over time, with no clear seasonal signal independent from year-to-year variability. Levels were correlated between fecal and manure samples, and in some cases autocorrelated, but not between manure and milk filters. Shiga toxins were nearly ubiquitous, and 10 to 18% of the lactating cows were potential shedders of E. coli O157 at least once during their time in the herds. E. coli virulence factors appear to persist in many areas of the farms and therefore contribute to transmission dynamics. PMID:25911478

  18. Phenotypic, antimicrobial susceptibility profile and virulence factors of Klebsiella pneumoniae isolated from buffalo and cow mastitic milk.

    Science.gov (United States)

    Osman, Kamelia M; Hassan, Hany M; Orabi, Ahmed; Abdelhafez, Ahmed S T

    2014-06-01

    Studies on the prevalence and virulence genes of Klebsiella mastitis pathogens in a buffalo population are undocumented. Also, the association of rmpA kfu, uge, magA, Aerobactin, K1 and K2 virulent factors with K. pneumoniae buffalo, and cow mastitis is unreported. The virulence of K. pneumoniae was evaluated through both phenotypic and molecular assays. In vivo virulence was assessed by the Vero cell cytotoxicity, suckling mouse assay and mice lethality test. Antimicrobial susceptibility was tested by disk diffusion method. The 45 K. pneumoniae isolates from buffalo (n = 10/232) and cow (n = 35/293) milk were isolated (45/525; 8.6%) and screened via PCR for seven virulence genes encoding uridine diphosphate galactose 4 epimerase encoding gene responsible for capsule and smooth lipopolysaccharide synthesis (uge), siderophores (kfu and aerobactin), protectines or invasins (rmpA and magA), and the capsule and hypermucoviscosity (K1 and K2). The most common virulence genes were rmpA, kfu, uge, and magA (77.8% each). Aerobactin and K1 genes were found at medium rates of 66.7% each and K2 (55.6%). The Vero cell cytotoxicity and LD (50) in mice were found in 100% of isolates. A multidrug resistance pattern was observed for 40% of the antimicrobials. The distribution of virulence profiles indicate a role of rmpA, kfu, uge, magA, Aerobactin, and K1 and K2 in pathogenicity of K. pneumoniae in udder infections and invasiveness, and constitutes a threat for vulnerable animals, even more if they are in combination with antibiotic resistance.

  19. Phenotypic, antimicrobial susceptibility profile and virulence factors of Klebsiella pneumoniae isolated from buffalo and cow mastitic milk

    Science.gov (United States)

    Osman, Kamelia M; Hassan, Hany M; Orabi, Ahmed; Abdelhafez, Ahmed S T

    2014-01-01

    Studies on the prevalence and virulence genes of Klebsiella mastitis pathogens in a buffalo population are undocumented. Also, the association of rmpA kfu, uge, magA, Aerobactin, K1 and K2 virulent factors with K. pneumoniae buffalo, and cow mastitis is unreported. The virulence of K. pneumoniae was evaluated through both phenotypic and molecular assays. In vivo virulence was assessed by the Vero cell cytotoxicity, suckling mouse assay and mice lethality test. Antimicrobial susceptibility was tested by disk diffusion method. The 45 K. pneumoniae isolates from buffalo (n = 10/232) and cow (n = 35/293) milk were isolated (45/525; 8.6%) and screened via PCR for seven virulence genes encoding uridine diphosphate galactose 4 epimerase encoding gene responsible for capsule and smooth lipopolysaccharide synthesis (uge), siderophores (kfu and aerobactin), protectines or invasins (rmpA and magA), and the capsule and hypermucoviscosity (K1 and K2). The most common virulence genes were rmpA, kfu, uge, and magA (77.8% each). Aerobactin and K1 genes were found at medium rates of 66.7% each and K2 (55.6%). The Vero cell cytotoxicity and LD (50) in mice were found in 100% of isolates. A multidrug resistance pattern was observed for 40% of the antimicrobials. The distribution of virulence profiles indicate a role of rmpA, kfu, uge, magA, Aerobactin, and K1 and K2 in pathogenicity of K. pneumoniae in udder infections and invasiveness, and constitutes a threat for vulnerable animals, even more if they are in combination with antibiotic resistance. PMID:24915048

  20. Virulence Attributes of Low-Virulence Organisms

    Directory of Open Access Journals (Sweden)

    Bryan Larsen

    1994-01-01

    virulence organisms present in the female lower genital tract, we are beginning to identify some of their virulence attributes. Examples from the work of our laboratory include the hemolysin of Gardnerella vaginalis and an immunosuppressive mycotoxin produced by Candida albicans. Demonstrating the coordinate expression (or other control mechanisms of virulence factors in these sometimes innocuous and sometimes inimical organisms represents the next frontier in the study of normal vaginal microbiology.

  1. Enterococcus Species in the Oral Cavity: Prevalence, Virulence Factors and Antimicrobial Susceptibility

    National Research Council Canada - National Science Library

    Komiyama, Edson Yukio; Lepesqueur, Laura Soares Souto; Yassuda, Cinthia Gomes; Samaranayake, Lakshman P; Parahitiyawa, Nipuna B; Balducci, Ivan; Koga-Ito, Cristiane Yumi

    2016-01-01

    .... faecalis isolates, in particular, were evaluated for virulence attributes such as their biofilm formation potential, and susceptibility to antimicrobials and an antiseptic, chlorhexidine gluconate...

  2. Differential compartmentalization of Streptococcus pyogenes virulence factors and host protein binding properties as a mechanism for host adaptation.

    Science.gov (United States)

    Kilsgård, Ola; Karlsson, Christofer; Malmström, Erik; Malmström, Johan

    2016-11-01

    Streptococcus pyogenes is an important human pathogen responsible for substantial morbidity and mortality worldwide. Although S. pyogenes is a strictly human pathogen with no other known animal reservoir, several murine infection models exist to explore different aspects of the bacterial pathogenesis. Inoculating mice with wild-type S. pyogenes strains can result in the generation of new bacterial phenotypes that are hypervirulent compared to the original inoculum. In this study, we used a serial mass spectrometry based proteomics strategy to investigate if these hypervirulent strains have an altered distribution of virulence proteins across the intracellular, surface associated and secreted bacterial compartments and if any change in compartmentalization can alter the protein-protein interaction network between bacteria and host proteins. Quantitative analysis of the S. pyogenes surface and secreted proteomes revealed that animal passaged strains are associated with significantly higher amount of virulence factors on the bacterial surface and in the media. This altered virulence factor compartmentalization results in increased binding of several mouse plasma proteins to the bacterial surface, a trend that was consistent for mouse plasma from several different mouse strains. In general, both the wild-type strain and animal passaged strain were capable of binding high amounts of human plasma proteins. However, compared to the non-passaged strains, the animal passaged strains displayed an increased ability to bind mouse plasma proteins, in particular for M protein binders, indicating that the increased affinity for mouse blood plasma proteins is a consequence of host adaptation of this pathogen to a new host. In conclusion, plotting the total amount of virulence factors against the total amount of plasma proteins associated to the bacterial surface could clearly separate out animal passaged strains from wild type strains indicating a virulence model that could

  3. Comparison of Antibiotic Resistance and Virulence Factors among Escherichia coli Isolated from Conventional and Free-Range Poultry

    Directory of Open Access Journals (Sweden)

    Vanessa L. Koga

    2015-01-01

    Full Text Available Microbiological contamination in commercial poultry production has caused concerns for human health because of both the presence of pathogenic microorganisms and the increase in antimicrobial resistance in bacterial strains that can cause treatment failure of human infections. The aim of our study was to analyze the profile of antimicrobial resistance and virulence factors of E. coli isolates from chicken carcasses obtained from different farming systems (conventional and free-range poultry. A total of 156 E. coli strains were isolated and characterized for genes encoding virulence factors described in extraintestinal pathogenic E. coli (ExPEC. Antimicrobial susceptibility testing was performed for 15 antimicrobials, and strains were confirmed as extended spectrum of β-lactamases- (ESBLs- producing E. coli by phenotypic and genotypic tests. The results indicated that strains from free-range poultry have fewer virulence factors than strains from conventional poultry. Strains from conventionally raised chickens had a higher frequency of antimicrobial resistance for all antibiotics tested and also exhibited genes encoding ESBL and AmpC, unlike free-range poultry isolates, which did not. Group 2 CTX-M and CIT were the most prevalent ESBL and AmpC genes, respectively. The farming systems of poultries can be related with the frequency of virulence factors and resistance to antimicrobials in bacteria.

  4. Carbon nanoparticles in lateral flow methods to detect genes encoding virulence factors of Shiga toxin-producing Escherichia coli

    NARCIS (Netherlands)

    Noguera, P.; Posthuma-Trumpie, G.A.; Tuil, van M.; Wal, van der F.J.; Boer, de A.; Moers, A.P.H.A.; Amerongen, van A.

    2011-01-01

    The use of carbon nanoparticles is shown for the detection and identification of different Shiga toxin-producing Escherichia coli virulence factors (vt1, vt2, eae and ehxA) and a 16S control (specific for E. coli) based on the use of lateral flow strips (nucleic acid lateral flow immunoassay,

  5. Genogrouping and incidence of virulence factors of Enterococcus faecalis in liver transplant patients differ from blood culture and fecal isolates

    NARCIS (Netherlands)

    Waar, K; Muscholl-Silberhorn, AB; Slooff, MJH; Harmsen, HJM; Degener, JE; Willems, Rob J. L.

    2002-01-01

    Enterococcus faecalis is a leading cause of infections in liver transplant patients. This study reviewed the incidence of virulence factors such as hemolysin, gelatinase, aggregation substances (asa1 and asa373), or the enterococcal surface protein (Esp) in isolates from liver transplant patients.

  6. Virulence Factors of Pseudomonas aeruginosa Induce Both the Unfolded Protein and Integrated Stress Responses in Airway Epithelial Cells

    NARCIS (Netherlands)

    van 't Wout, Emily F A; van Schadewijk, Annemarie; van Boxtel, Ria; Dalton, Lucy E; Clarke, Hanna J; Tommassen, J.P.M.; Marciniak, Stefan J; Hiemstra, Pieter S

    Pseudomonas aeruginosa infection can be disastrous in chronic lung diseases such as cystic fibrosis and chronic obstructive pulmonary disease. Its toxic effects are largely mediated by secreted virulence factors including pyocyanin, elastase and alkaline protease (AprA). Efficient functioning of the

  7. Prevalence, virulence factor genes and antibiotic resistance of Bacillus cereus sensu lato isolated from dairy farms and traditional dairy products

    DEFF Research Database (Denmark)

    Owusu-Kwarteng, James; Wuni, Alhassan; Akabanda, Fortune

    2017-01-01

    Background: B. cereus are of particular interest in food safety and public health because of their capacity to cause food spoilage and disease through the production of various toxins. The aim of this study was to determine the prevalence, virulence factor genes and antibiotic resistance profile...

  8. Revisiting the Escherichia coli polysaccharide capsule as a virulence factor during urinary tract infection: contribution to intracellular biofilm development.

    Science.gov (United States)

    Goller, Carlos C; Seed, Patrick C

    2010-01-01

    The treatment of urinary tract infections (UTIs) is becoming increasingly challenging as uropathogenic Escherichia coli (UPEC) becomes more resistant to the most widely prescribed oral antibiotics. The treatment of UTIs may also be complicated by the inherent lifestyle of UPEC in the urinary tract, revealed in recent studies demonstrating bacterial invasion into bladder epithelial cells, the formation of intracellular bacterial communities (IBCs; biofilm-like colonies in the host cell cytosol), and chronic intracellular persistence with subversion of normal immune surveillance. Identifying key targets in the pathogenesis of UTIs, including IBC formation, will be crucial to replenish the arsenal of treatments for UTIs. Focused on elucidating bacterial components that underpin the development of IBCs, Anderson et al. recently demonstrated a novel role for the K capsule polysaccharide in IBC formation. Without K capsule, intracellular UPEC failed to undergo normal IBC formation, the intracellular bacteria failed to preclude neutrophil infiltration, and UPEC did not undergo serial cycles of intracellular proliferation, resulting in attenuation of the infection. This study also demonstrated an interconnection between sialic acid homeostasis and IBC formation, demonstrating a unique role for this amino sugar in biofilm formation. This study provides evidence for an expanded role for K capsule in the intracellular and extracellular pathogenesis of UTI, and provides additional rationale for the development of small molecule inhibitors of capsule biogenesis as anti-virulence therapeutics.

  9. Examining the virulence of Candida albicans transcription factor mutants using Galleria mellonella and mouse infection models.

    Science.gov (United States)

    Amorim-Vaz, Sara; Delarze, Eric; Ischer, Françoise; Sanglard, Dominique; Coste, Alix T

    2015-01-01

    The aim of the present study was to identify Candida albicans transcription factors (TFs) involved in virulence. Although mice are considered the gold-standard model to study fungal virulence, mini-host infection models have been increasingly used. Here, barcoded TF mutants were first screened in mice by pools of strains and fungal burdens (FBs) quantified in kidneys. Mutants of unannotated genes which generated a kidney FB significantly different from that of wild-type were selected and individually examined in Galleria mellonella. In addition, mutants that could not be detected in mice were also tested in G. mellonella. Only 25% of these mutants displayed matching phenotypes in both hosts, highlighting a significant discrepancy between the two models. To address the basis of this difference (pool or host effects), a set of 19 mutants tested in G. mellonella were also injected individually into mice. Matching FB phenotypes were observed in 50% of the cases, highlighting the bias due to host effects. In contrast, 33.4% concordance was observed between pool and single strain infections in mice, thereby highlighting the bias introduced by the "pool effect." After filtering the results obtained from the two infection models, mutants for MBF1 and ZCF6 were selected. Independent marker-free mutants were subsequently tested in both hosts to validate previous results. The MBF1 mutant showed impaired infection in both models, while the ZCF6 mutant was only significant in mice infections. The two mutants showed no obvious in vitro phenotypes compared with the wild-type, indicating that these genes might be specifically involved in in vivo adapt.

  10. Examining the virulence of Candida albicans transcription factor mutants using Galleria mellonella and mouse infection models

    Directory of Open Access Journals (Sweden)

    Sara eAmorim-Vaz

    2015-05-01

    Full Text Available The aim of the present study was to identify C. albicans transcription factors (TF involved in virulence. Although mice are considered the gold-standard model to study fungal virulence, mini-host infection models have been increasingly used. Here, barcoded TF mutants were first screened in mice by pools of strains and fungal burdens quantified in kidneys. Mutants of unannotated genes which generated a kidney fungal burden significantly different from that of wild-type were selected and individually examined in G. mellonella. In addition, mutants that could not be detected in mice were also tested in G. mellonella. Only 25 % of these mutants displayed matching phenotypes in both hosts, highlighting a significant discrepancy between the two models. To address the basis of this difference (pool or host effects, a set of 19 mutants tested in G. mellonella were also injected individually into mice. Matching fungal burden phenotypes were observed in 50 % of the cases, highlighting the bias due to host effects. In contrast, 33.4 % concordance was observed between pool and single strain infections in mice, thereby highlighting the bias introduced by the pool effect. After filtering the results obtained from the two infection models, mutants for MBF1 and ZCF6 were selected. Independent marker-free mutants were subsequently tested in both hosts to validate previous results. The MBF1 mutant showed impaired infection in both models, while the ZCF6 mutant was only significant in mice infections. The two mutants showed no obvious in vitro phenotypes compared with the wild-type, indicating that these genes might be specifically involved in in vivo adaptation.

  11. Listeria monocytogenes virulence factor secretion: don’t leave the cell without a chaperone

    Directory of Open Access Journals (Sweden)

    Laty Adriella Cahoon

    2014-02-01

    Full Text Available In Gram-positive bacteria, the secretion of proteins requires translocation of polypeptides across the bacterial membrane into the highly charged environment of the membrane-cell wall interface. Here, proteins must be folded and often further delivered across the matrix of the cell wall. While many aspects of protein secretion have been well studied in Gram-negative bacteria, which possess both an inner and outer membrane, generally less attention has been given to the mechanics of protein secretion across the single cell membrane of Gram-positive bacteria. In this review, we focus on the role of a post-translocation secretion chaperone in Listeria monocytogenes known as PrsA2, and compare what is known regarding PrsA2 with PrsA homologues in other Gram-positive bacteria. PrsA2 is a member of a family of membrane-associated lipoproteins that contribute to the folding and stability of secreted proteins as they cross the bacterial membrane. PrsA2 contributes to the integrity of the L. monocytogenes cell wall as well as swimming motility and bacterial resistance to osmotic stress, however its most critical role may be its requirement for L. monocytogenes virulence and viability within host cells. A better understanding of the role of PrsA2 and PrsA-like homologues will provide insight into the dynamics of protein folding and stability in Gram-positive bacteria and may result in new strategies for optimizing protein secretion as well as inhibiting the production of virulence factors.

  12. Virulence factors and mechanisms of antimicrobial resistance in Shigella strains from periurban areas of Lima (Peru).

    Science.gov (United States)

    Lluque, Angela; Mosquito, Susan; Gomes, Cláudia; Riveros, Maribel; Durand, David; Tilley, Drake H; Bernal, María; Prada, Ana; Ochoa, Theresa J; Ruiz, Joaquim

    2015-01-01

    The study was aimed to describe the serotype, mechanisms of antimicrobial resistance, and virulence determinants in Shigella spp. isolated from Peruvian children. Eighty three Shigella spp. were serogrouped and serotyped being established the antibiotic susceptibility. The presence of 12 virulence factors (VF) and integrase 1 and 2, along with commonly found antibiotic resistance genes was established by PCR. S. flexneri was the most relevant serogroup (55 isolates, 66%), with serotype 2a most frequently detected (27 of 55, 49%), followed by S. boydii and S. sonnei at 12 isolates each (14%) and S. dysenteriae (four isolates, 5%). Fifty isolates (60%) were multi-drug resistant (MDR) including 100% of S. sonnei and 64% of S. flexneri. Resistance levels were high to trimethoprim-sulfamethoxazole (86%), tetracycline (74%), ampicillin (67%), and chloramphenicol (65%). Six isolates showed decreased azithromycin susceptibility. No isolate was resistant to nalidixic acid, ciprofloxacin, nitrofurantoin, or ceftriaxone. The most frequent resistance genes were sul2 (95%), tet(B) (92%), cat (80%), dfrA1 (47%), blaOXA-1like (40%), with intl1 and intl2 detected in 51 and 52% of the isolates, respectively. Thirty-one different VF profiles were observed, being the ipaH (100%), sen (77%), virA and icsA (75%) genes the most frequently found. Differences in the prevalence of VF were observed between species with S. flexneri isolates, particularly serotype 2a, possessing high numbers of VF. In conclusion, this study highlights the high heterogeneity of Shigella VF and resistance genes, and prevalence of MDR organisms within this geographic region. Copyright © 2015 Elsevier GmbH. All rights reserved.

  13. The RNA chaperone Hfq impacts growth, metabolism and production of virulence factors in Yersinia enterocolitica.

    Directory of Open Access Journals (Sweden)

    Tamara Kakoschke

    Full Text Available To adapt to changes in environmental conditions, bacteria regulate their gene expression at the transcriptional but also at the post-transcriptional level, e.g. by small RNAs (sRNAs which modulate mRNA stability and translation. The conserved RNA chaperone Hfq mediates the interaction of many sRNAs with their target mRNAs, thereby playing a global role in fine-tuning protein production. In this study, we investigated the significance of Hfq for the enteropathogen Yersina enterocolitica serotype O:8. Hfq facilitated optimal growth in complex and minimal media. Our comparative protein analysis of parental and hfq-negative strains suggested that Hfq promotes lipid metabolism and transport, cell redox homeostasis, mRNA translation and ATP synthesis, and negatively affects carbon and nitrogen metabolism, transport of siderophore and peptides and tRNA synthesis. Accordingly, biochemical tests indicated that Hfq represses ornithine decarboxylase activity, indole production and utilization of glucose, mannitol, inositol and 1,2-propanediol. Moreover, Hfq repressed production of the siderophore yersiniabactin and its outer membrane receptor FyuA. In contrast, hfq mutants exhibited reduced urease production. Finally, strains lacking hfq were more susceptible to acidic pH and oxidative stress. Unlike previous reports in other Gram-negative bacteria, Hfq was dispensable for type III secretion encoded by the virulence plasmid. Using a chromosomally encoded FLAG-tagged Hfq, we observed increased production of Hfq-FLAG in late exponential and stationary phases. Overall, Hfq has a profound effect on metabolism, resistance to stress and modulates the production of two virulence factors in Y. enterocolitica, namely urease and yersiniabactin.

  14. Comparative "-omics" in Mycoplasma pneumoniae Clinical Isolates Reveals Key Virulence Factors.

    Directory of Open Access Journals (Sweden)

    Maria Lluch-Senar

    Full Text Available The human respiratory tract pathogen M. pneumoniae is one of the best characterized minimal bacterium. Until now, two main groups of clinical isolates of this bacterium have been described (types 1 and 2, differing in the sequence of the P1 adhesin gene. Here, we have sequenced the genomes of 23 clinical isolates of M. pneumoniae. Studying SNPs, non-synonymous mutations, indels and genome rearrangements of these 23 strains and 4 previously sequenced ones, has revealed new subclasses in the two main groups, some of them being associated with the country of isolation. Integrative analysis of in vitro gene essentiality and mutation rates enabled the identification of several putative virulence factors and antigenic proteins; revealing recombination machinery, glycerol metabolism and peroxide production as possible factors in the genetics and physiology of these pathogenic strains. Additionally, the transcriptomes and proteomes of two representative strains, one from each of the two main groups, have been characterized to evaluate the impact of mutations on RNA and proteins levels. This study has revealed that type 2 strains show higher expression levels of CARDS toxin, a protein recently shown to be one of the major factors of inflammation. Thus, we propose that type 2 strains could be more toxigenic than type 1 strains of M. pneumoniae.

  15. Biogenesis of Enterococcis faecium biofilms

    OpenAIRE

    Paganelli, F.L.

    2015-01-01

    Nosocomial infections caused by Enterococcus faecium have rapidly increased worldwide and treatment options become more limited. The presence of antibiotic resistance genes and virulence factors in pathogenic E. faecium contribute to difficult-to-treat infections, frequently biofilm mediated, such as artificial-medical-device-associated infections. Biofilm is defined as a population of bacteria, encased in an extracellular matrix, attached to biotic surfaces, such as plants, animals and the h...

  16. Real-Time Characterization of Virulence Factor Expression in Yersinia pestis Using a Green Fluorescent Protein Reporter System

    Energy Technology Data Exchange (ETDEWEB)

    Forde, C; Rocco, J; Fitch, J P; McCutchen-Maloney, S

    2004-06-09

    A real-time reporter system was developed to monitor the thermal induction of virulence factors in Yersinia pestis. The reporter system consists of a plasmid in Y. pestis in which the expression of green fluorescent protein (GFP) is under the control of the promoters for six virulence factors, yopE, sycE, yopK, yopT, yscN, and lcrE/yopN, which are all components of the Type III secretion virulence mechanism of Y. pestis. Induction of the expression of these genes in vivo was determined by the increase in fluorescence intensity of GFP in real time. Basal expression levels observed for the Y. pestis promoters, expressed as percentages of the positive control with GFP under the control of the lac promoter, were: yopE (15%), sycE (15%), yopK (13%), yopT (4%), lcrE (3.3%) and yscN (0.8%). The yopE reporter showed the strongest gene induction following temperature transition from 26 C to 37 C. The induction levels of the other virulence factors, expressed as percentages of yopE induction, were: yopK (57%), sycE (9%), yscN (3%), lcrE (3%), and yopT (2%). The thermal induction of each of these promoter fusions was repressed by calcium, and the ratios of the initial rates of thermal induction without calcium supplementation compared to the rate with calcium supplementation were: yopE (11 fold), yscN (7 fold), yopK (6 fold), lcrE (3 fold), yopT (2 fold), and sycE (2 fold). This work demonstrates a novel approach to quantify gene induction and provides a method to rapidly determine the effects of external stimuli on expression of Y. pestis virulence factors in real time, in living cells.

  17. A response regulator promotes Francisella tularensis intramacrophage growth by repressing an anti-virulence factor.

    Science.gov (United States)

    Ramsey, Kathryn M; Dove, Simon L

    2016-08-01

    The orphan response regulator PmrA is essential for the intramacrophage growth and survival of Francisella tularensis. PmrA was thought to promote intramacrophage growth by binding directly to promoters on the Francisella Pathogenicity Island (FPI) and positively regulating the expression of FPI genes, which encode a Type VI secretion system required for intramacrophage growth. Using both ChIP-Seq and RNA-Seq we identify those regions of the F. tularensis chromosome occupied by PmrA and those genes that are regulated by PmrA. We find that PmrA associates with 252 distinct regions of the F. tularensis chromosome, but exerts regulatory effects at only a few of these locations. Rather than by functioning directly as an activator of FPI gene expression we present evidence that PmrA promotes intramacrophage growth by repressing the expression of a single target gene we refer to as priM (PmrA-repressed inhibitor of intramacrophage growth). Our findings thus indicate that the role of PmrA in facilitating intracellular growth is to repress a previously unknown anti-virulence factor. PriM is the first bacterially encoded factor to be described that can interfere with the intramacrophage growth and survival of F. tularensis. © 2016 John Wiley & Sons Ltd.

  18. [The role of persistence and virulence factors in microecological changes in a humans].

    Science.gov (United States)

    Usviatsov, B Ia; Khusnutdinova, L M; Parshuta, L I; Khanina, E A; Dolgov, V A; Porshina, O V

    2006-01-01

    The patterns of persistence and virulence factors expression in the representatives of human microbial biocenosis depends on a complex of the environmental conditions: influence of microbes-symbionts, biotope peculiarities, properties of microorganisms located within eukaryotes. Interactions of symbionts in pairs "indigen-indigen" isolated from mucous membrane of tonsils in healthy persons, did not lead to changes in expression of pathogenic properties. Interinfluence in pairs "pathogen-indigen" and "indigen-indigen", isolated from patients with chronic tonsilitis were accompanied by an increase of anti-lysozyme, hemolytic and lecithovitellase activities. Migration of strains of non-enzymatized gram-negative bacteria (NEYNB) from nasal into tympanic cavity in experimental acute purulent otitis is connected with an earlier increase of their number in the nasal cavity and the expression of anti-lysozyme activity. In acute and chronic pyoderma, expression of ALA is more marked in bacteria from a perifocal damage in contrast to focal damage of normal skin. In conditions of interaction between erythrocytes and staphylococcal clones with different levels of expression of pathogenic factors, differences were observed in dynamics of hemolytic and anti-hemoglobin activities.

  19. Plant peroxisomes: biogenesis and function.

    Science.gov (United States)

    Hu, Jianping; Baker, Alison; Bartel, Bonnie; Linka, Nicole; Mullen, Robert T; Reumann, Sigrun; Zolman, Bethany K

    2012-06-01

    Peroxisomes are eukaryotic organelles that are highly dynamic both in morphology and metabolism. Plant peroxisomes are involved in numerous processes, including primary and secondary metabolism, development, and responses to abiotic and biotic stresses. Considerable progress has been made in the identification of factors involved in peroxisomal biogenesis, revealing mechanisms that are both shared with and diverged from non-plant systems. Furthermore, recent advances have begun to reveal an unexpectedly large plant peroxisomal proteome and have increased our understanding of metabolic pathways in peroxisomes. Coordination of the biosynthesis, import, biochemical activity, and degradation of peroxisomal proteins allows for highly dynamic responses of peroxisomal metabolism to meet the needs of a plant. Knowledge gained from plant peroxisomal research will be instrumental to fully understanding the organelle's dynamic behavior and defining peroxisomal metabolic networks, thus allowing the development of molecular strategies for rational engineering of plant metabolism, biomass production, stress tolerance, and pathogen defense.

  20. Phenotypic Assays to Determine Virulence Factors of Uropathogenic Escherichia coli (UPEC) Isolates and their Correlation with Antibiotic Resistance Pattern.

    Science.gov (United States)

    Tabasi, Mohsen; Asadi Karam, Mohammad Reza; Habibi, Mehri; Yekaninejad, Mir Saeed; Bouzari, Saeid

    2015-08-01

    Urinary tract infection caused by uropathogenic Escherichia coli (UPEC) strains is one of the most important infections in the world. UPEC encode widespread virulence factors closely related with pathogenesis of the bacteria. The purpose of this study was to evaluate the presence of different phenotypic virulence markers in UPEC isolates and determine their correlation with antibiotic resistance pattern. UPEC isolates from patients with different clinical symptoms of UTI were collected and screened for biofilm and hemolysin production, mannose resistant, and mannose sensitive hemagglutination (MRHA and MSHA, respectively). In addition, antimicrobial resistance pattern and ESBL-producing isolates were recorded. Of the 156 UPEC isolates, biofilm and hemolysin formation was seen in 133 (85.3%) and 53 (34%) isolates, respectively. Moreover, 98 (62.8%) and 58 (37.2%) isolates showed the presence of Types 1 fimbriae (MSHA) and P fimbriae (MRHA), respectively. Our results also showed a relationship between biofilm formation in UPEC isolated from acute cystitis patients and recurrent UTI cases. Occurrence of UTI was dramatically correlated with the patients' profiles. We observed that the difference in antimicrobial susceptibilities of the biofilm and nonbiofilm former isolates was statistically significant. The UPEC isolates showed the highest resistance to ampicillin, tetracycline, amoxicillin, and cotrimoxazole. Moreover, 26.9% of isolates were ESBL producers. This study indicated that there is a relationship between the phenotypic virulence traits of the UPEC isolates, patients' profiles, and antibiotic resistance. Detection of the phenotypic virulence factors could help to improve understanding of pathogenesis of UPEC isolates and better medical intervention.

  1. Functional and Structural Properties of a Novel Protein and Virulence Factor (Protein sHIP) in Streptococcus pyogenes *

    Science.gov (United States)

    Wisniewska, Magdalena; Happonen, Lotta; Kahn, Fredrik; Varjosalo, Markku; Malmström, Lars; Rosenberger, George; Karlsson, Christofer; Cazzamali, Giuseppe; Pozdnyakova, Irina; Frick, Inga-Maria; Björck, Lars; Streicher, Werner; Malmström, Johan; Wikström, Mats

    2014-01-01

    Streptococcus pyogenes is a significant bacterial pathogen in the human population. The importance of virulence factors for the survival and colonization of S. pyogenes is well established, and many of these factors are exposed to the extracellular environment, enabling bacterial interactions with the host. In the present study, we quantitatively analyzed and compared S. pyogenes proteins in the growth medium of a strain that is virulent to mice with a non-virulent strain. Particularly, one of these proteins was present at significantly higher levels in stationary growth medium from the virulent strain. We determined the three-dimensional structure of the protein that showed a unique tetrameric organization composed of four helix-loop-helix motifs. Affinity pull-down mass spectrometry analysis in human plasma demonstrated that the protein interacts with histidine-rich glycoprotein (HRG), and the name sHIP (streptococcal histidine-rich glycoprotein-interacting protein) is therefore proposed. HRG has antibacterial activity, and when challenged by HRG, sHIP was found to rescue S. pyogenes bacteria. This and the finding that patients with invasive S. pyogenes infection respond with antibody production against sHIP suggest a role for the protein in S. pyogenes pathogenesis. PMID:24825900

  2. Functional and structural properties of a novel protein and virulence factor (Protein sHIP) in Streptococcus pyogenes.

    Science.gov (United States)

    Wisniewska, Magdalena; Happonen, Lotta; Kahn, Fredrik; Varjosalo, Markku; Malmström, Lars; Rosenberger, George; Karlsson, Christofer; Cazzamali, Giuseppe; Pozdnyakova, Irina; Frick, Inga-Maria; Björck, Lars; Streicher, Werner; Malmström, Johan; Wikström, Mats

    2014-06-27

    Streptococcus pyogenes is a significant bacterial pathogen in the human population. The importance of virulence factors for the survival and colonization of S. pyogenes is well established, and many of these factors are exposed to the extracellular environment, enabling bacterial interactions with the host. In the present study, we quantitatively analyzed and compared S. pyogenes proteins in the growth medium of a strain that is virulent to mice with a non-virulent strain. Particularly, one of these proteins was present at significantly higher levels in stationary growth medium from the virulent strain. We determined the three-dimensional structure of the protein that showed a unique tetrameric organization composed of four helix-loop-helix motifs. Affinity pull-down mass spectrometry analysis in human plasma demonstrated that the protein interacts with histidine-rich glycoprotein (HRG), and the name sHIP (streptococcal histidine-rich glycoprotein-interacting protein) is therefore proposed. HRG has antibacterial activity, and when challenged by HRG, sHIP was found to rescue S. pyogenes bacteria. This and the finding that patients with invasive S. pyogenes infection respond with antibody production against sHIP suggest a role for the protein in S. pyogenes pathogenesis. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  3. Posttranslational modification of mitochondrial transcription factor A in impaired mitochondria biogenesis: implications in diabetic retinopathy and metabolic memory phenomenon.

    Science.gov (United States)

    Santos, Julia M; Mishra, Manish; Kowluru, Renu A

    2014-04-01

    Mitochondrial transcription factor A (TFAM) is one of the key regulators of the transcription of mtDNA. In diabetes, despite increase in gene transcripts of TFAM, its protein levels in the mitochondria are decreased and mitochondria copy numbers become subnormal. The aim of this study is to investigate the mechanism(s) responsible for decreased mitochondrial TFAM in diabetes. Using retinal endothelial cells, we have investigated the effect of overexpression of cytosolic chaperone, Hsp70, and TFAM on glucose-induced decrease in mitochondrial TFAM levels, and the transcription of mtDNA-encoded genes, NADH dehydrogenase subunit 6 (ND6) and cytochrome b (Cytb). To investigate the role of posttranslational modifications in subnormal mitochondrial TFAM, ubiquitination of TFAM was assessed, and the results were confirmed in the retina from streptozotocin-induced diabetic rats. While overexpression of Hsp70 failed to prevent glucose-induced decrease in mitochondrial TFAM and transcripts of ND6 and Cytb, overexpression of TFAM ameliorated decrease in its mitochondrial protein levels and transcriptional activity. TFAM was ubiquitinated by high glucose, and PYR-41, an inhibitor of ubiquitination, prevented TFAM ubiquitination and restored the transcriptional activity. Similarly, TFAM was ubiquitinated in the retina from diabetic rats, and it continued to be modified after reinstitution of normal glycemia. Our results clearly imply that the ubiquitination of TFAM impedes its transport to the mitochondria resulting in subnormal mtDNA transcription and mitochondria dysfunction, and inhibition of ubiquitination restores mitochondrial homeostasis. Reversal of hyperglycemia does not provide any benefit to TFAM ubiquitination. Thus, strategies targeting posttranslational modification could provide an avenue to preserve mitochondrial homeostasis, and inhibit the development/progression of diabetic retinopathy. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. A trimeric lipoprotein assists in trimeric autotransporter biogenesis in enterobacteria.

    Science.gov (United States)

    Grin, Iwan; Hartmann, Marcus D; Sauer, Guido; Hernandez Alvarez, Birte; Schütz, Monika; Wagner, Samuel; Madlung, Johannes; Macek, Boris; Felipe-Lopez, Alfonso; Hensel, Michael; Lupas, Andrei; Linke, Dirk

    2014-03-14

    Trimeric autotransporter adhesins (TAAs) are important virulence factors of many Gram-negative bacterial pathogens. TAAs form fibrous, adhesive structures on the bacterial cell surface. Their N-terminal extracellular domains are exported through a C-terminal membrane pore; the insertion of the pore domain into the bacterial outer membrane follows the rules of β-barrel transmembrane protein biogenesis and is dependent on the essential Bam complex. We have recently described the full fiber structure of SadA, a TAA of unknown function in Salmonella and other enterobacteria. In this work, we describe the structure and function of SadB, a small inner membrane lipoprotein. The sadB gene is located in an operon with sadA; orthologous operons are only found in enterobacteria, whereas other TAAs are not typically associated with lipoproteins. Strikingly, SadB is also a trimer, and its co-expression with SadA has a direct influence on SadA structural integrity. This is the first report of a specific export factor of a TAA, suggesting that at least in some cases TAA autotransport is assisted by additional periplasmic proteins.

  5. A Trimeric Lipoprotein Assists in Trimeric Autotransporter Biogenesis in Enterobacteria*

    Science.gov (United States)

    Grin, Iwan; Hartmann, Marcus D.; Sauer, Guido; Hernandez Alvarez, Birte; Schütz, Monika; Wagner, Samuel; Madlung, Johannes; Macek, Boris; Felipe-Lopez, Alfonso; Hensel, Michael; Lupas, Andrei; Linke, Dirk

    2014-01-01

    Trimeric autotransporter adhesins (TAAs) are important virulence factors of many Gram-negative bacterial pathogens. TAAs form fibrous, adhesive structures on the bacterial cell surface. Their N-terminal extracellular domains are exported through a C-terminal membrane pore; the insertion of the pore domain into the bacterial outer membrane follows the rules of β-barrel transmembrane protein biogenesis and is dependent on the essential Bam complex. We have recently described the full fiber structure of SadA, a TAA of unknown function in Salmonella and other enterobacteria. In this work, we describe the structure and function of SadB, a small inner membrane lipoprotein. The sadB gene is located in an operon with sadA; orthologous operons are only found in enterobacteria, whereas other TAAs are not typically associated with lipoproteins. Strikingly, SadB is also a trimer, and its co-expression with SadA has a direct influence on SadA structural integrity. This is the first report of a specific export factor of a TAA, suggesting that at least in some cases TAA autotransport is assisted by additional periplasmic proteins. PMID:24369174

  6. Identification of New Virulence Factors and Vaccine Candidates for Yersinia pestis

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    Jourdan A. Andersson

    2017-10-01

    Full Text Available Earlier, we reported the identification of new virulence factors/mechanisms of Yersinia pestis using an in vivo signature-tagged mutagenesis (STM screening approach. From this screen, the role of rbsA, which encodes an ATP-binding protein of ribose transport system, and vasK, an essential component of the type VI secretion system (T6SS, were evaluated in mouse models of plague and confirmed to be important during Y. pestis infection. However, many of the identified genes from the screen remained uncharacterized. In this study, in-frame deletion mutants of ypo0815, ypo2884, ypo3614-3168 (cyoABCDE, and ypo1119-1120, identified from the STM screen, were generated. While ypo0815 codes for a general secretion pathway protein E (GspE of the T2SS, the ypo2884-encoded protein has homology to the βγ crystallin superfamily, cyoABCDE codes for the cytochrome o oxidase operon, and the ypo1119-1120 genes are within the Tol-Pal system which has multiple functions. Additionally, as our STM screen identified three T6SS-associated genes, and, based on in silico analysis, six T6SS clusters and multiple homologs of the T6SS effector hemolysin-coregulated protein (Hcp exist in Y. pestis CO92, we also targeted these T6SS clusters and effectors for generating deletion mutants. These deletion mutant strains exhibited varying levels of attenuation (up to 100%, in bubonic or pneumonic murine infection models. The attenuation could be further augmented by generation of combinatorial deletion mutants, namely ΔlppΔypo0815, ΔlppΔypo2884, ΔlppΔcyoABCDE, ΔvasKΔhcp6, and Δypo2720-2733Δhcp3. We earlier showed that deletion of the lpp gene, which encodes Braun lipoprotein (Lpp and activates Toll-like receptor-2, reduced virulence of Y. pestis CO92 in murine models of bubonic and pneumonic plague. The surviving mice infected with ΔlppΔcyoABCDE, ΔvasKΔhcp6, and Δypo2720-2733Δhcp3 mutant strains were 55–100% protected upon subsequent re-challenge with wild

  7. Dietary L-glutamine supplementation increases Pasteurella multocida burden and the expression of its major virulence factors in mice.

    Science.gov (United States)

    Ren, Wenkai; Liu, Shuping; Chen, Shuai; Zhang, Fengmei; Li, Nengzhang; Yin, Jie; Peng, Yuanyi; Wu, Li; Liu, Gang; Yin, Yulong; Wu, Guoyao

    2013-10-01

    This study was conducted to determine the effects of graded doses of L-glutamine supplementation on the replication and distribution of Pasteurella multocida, and the expression of its major virulence factors in mouse model. Mice were randomly assigned to the basal diet supplemented with 0, 0.5, 1.0 or 2.0 % glutamine. Pasteurella multocida burden was detected in the heart, liver, spleen, lung and kidney after 12 h of P. multocida infection. The expression of major virulence factors, toll-like receptors (TLRs), proinflammatory cytokines (interleukin-1 beta, interleukin-6, and tumor necrosis factor alpha) and anti-oxidative factors (GPX1 and CuZnSOD) was analyzed in the lung and spleen. Dietary 0.5 % glutamine supplementation has little significant effect on these parameters, compared to those with basal diet. However, results showed that a high dose of glutamine supplementation increased the P. multocida burden (P multocida burden and the expression of its major virulence factors, while affecting the functions of the lung and spleen.

  8. Virulence factors of Escherichia coli isolated from diarrheic calves Fatores de virulência de Escherichia coli isolada de bezerros com diarréia

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    E.C. Rigobelo

    2006-06-01

    Full Text Available One hundred seventy-three Escherichia coli strains isolated from calves from northwestern São Paulo State, having diarrhea were examined for the production of thermolabile (LT and thermostable (ST enterotoxins and for the presence of virulence factors associated with bovine colibacillosis. Eighty-five (49.1% of the E.coli strains produced toxins; 53 isolates were detected as producing STa toxin, and 9 also produced LT toxin. By PCR, 23 isolates were shown to harbor only the LT-II gene. Nine (5.2% isolates harbored Shiga toxin genes: four carried the stx2 gene, four the stx1 gene and one carried both. Three of the isolates showing stx1 also carried the eae gene. Among the E. coli isolates examined for susceptibility to 10 antimicrobial agents, resistance to cephalothin (46.1%, was most commonly observed, followed by resistances to tetracycline (45.7%, trimethoprim-sulfadiazine (43.3% and ampicilin (41.0%. All isolates showed resistance to at least two antimicrobial agents; multidrug resistance was quite frequently encountered. Results showed that bovine E. coli produces some toxins and virulence factors, some of which may be involved in human disease. The isolates showed a high level of resistance to antimicrobial agents constituting a public health concern.Cento e setenta e três cepas de Escherichia coli isoladas de bezerros com diarréia provenientes da região noroeste do estado de São Paulo foram examinadas para a produção de enterotoxinas termolábil (LT e termoestável (ST, e examinadas quanto à presença de fatores de virulência associados a colibacilose bovina. Oitenta e cinco (49,1% das cepas de E. coli produziram toxinas, 53 cepas foram detectadas como produtoras de toxina STa, e nove dessas cepas também produziam toxina LT. Foram identificadas pela reação em cadeia de polimerase 23 cepas portadoras do gene LT-II. Nove (5,2% das cepas apresentavam os genes de toxina Shiga: quatro o gene stx 2, quatro o gene stx 1 e uma cepa

  9. Leishmania exosomes and other virulence factors: Impact on innate immune response and macrophage functions.

    Science.gov (United States)

    Atayde, Vanessa Diniz; Hassani, Kasra; da Silva Lira Filho, Alonso; Borges, Andrezza Raposo; Adhikari, Anupam; Martel, Caroline; Olivier, Martin

    2016-11-01

    Leishmania parasites are the causative agents of the leishmaniases, a collection of vector-borne diseases that range from simple cutaneous to fatal visceral forms. Employing potent immune modulation mechanisms, Leishmania is able to render the host macrophage inactive and persist inside its phagolysosome. In the last few years, the role of exosomes in Leishmania-host interactions has been increasingly investigated. For instance, it was reported that Leishmania exosome release is augmented following temperature shift, a condition mimicking parasite's entry into its mammalian host. Leishmania exosomes were found to strongly affect macrophage cell signaling and functions, similarly to whole parasites. Importantly, these vesicles were shown to be pro-inflammatory, capable to recruit neutrophils at their inoculation site exacerbating the pathology. In this review, we provide the most recent insights on the role of exosomes and other virulence factors, especially the surface protease GP63, in Leishmania-host interactions, deepening our knowledge on leishmaniasis and paving the way for the development of new therapeutics. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Bacteriocin synthesis in uropathogenic and commensal Escherichia coli: colicin E1 is a potential virulence factor

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    Vališová Zuzana

    2010-11-01

    Full Text Available Abstract Background Bacteriocin production is an important characteristic of E. coli strains of human origin. To date, 26 colicin and 9 microcin types have been analyzed on a molecular level allowing molecular detection of the corresponding genes. The production incidence of 29 bacteriocin types and E. coli phylogroups were tested in a set of 361 E. coli strains isolated from human urinary tract infections (UTI and in 411 control strains isolated from feces of patients without bacterial gut infection. Results Production of 17 and 20 individual bacteriocin types was found in the UTI and control strains, respectively. Microcin H47 encoding determinants were found more often among UTI strains compared to controls (37.9% and 27.0% respectively, p = 0.02 and strains producing microcin H47 belonged predominantly to phylogroup B2 when compared to other bacteriocin producers (67.4% and 36.7%, respectively; p vice versa suggesting that pColE1 was independently associated with pColIa in UTI strains. Conclusion E. coli strains isolated from human urinary tract infections showed increased incidence of microcin H47 and colicin E1 production, respectively. Moreover, colicin E1 itself appears to be a potentially important virulence factor of certain uropathogenic E. coli strains.

  11. Evidence for positive selection in putative virulence factors within the Paracoccidioides brasiliensis species complex.

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    Daniel R Matute

    Full Text Available Paracoccidioides brasiliensis is a dimorphic fungus that is the causative agent of paracoccidioidomycosis, the most important prevalent systemic mycosis in Latin America. Recently, the existence of three genetically isolated groups in P. brasiliensis was demonstrated, enabling comparative studies of molecular evolution among P. brasiliensis lineages. Thirty-two gene sequences coding for putative virulence factors were analyzed to determine whether they were under positive selection. Our maximum likelihood-based approach yielded evidence for selection in 12 genes that are involved in different cellular processes. An in-depth analysis of four of these genes showed them to be either antigenic or involved in pathogenesis. Here, we present evidence indicating that several replacement mutations in gp43 are under positive balancing selection. The other three genes (fks, cdc42 and p27 show very little variation among the P. brasiliensis lineages and appear to be under positive directional selection. Our results are consistent with the more general observations that selective constraints are variable across the genome, and that even in the genes under positive selection, only a few sites are altered. We present our results within an evolutionary framework that may be applicable for studying adaptation and pathogenesis in P. brasiliensis and other pathogenic fungi.

  12. Immunochemical properties of Proteus penneri lipopolysaccharides--one of the major Proteus sp. virulence factors.

    Science.gov (United States)

    Palusiak, Agata

    2013-10-18

    Proteus penneri, like the other seven species from the genus, are Gram-negative, peritrichously flagellated rods capable of swarming growth on humid solid media. These bacteria are human opportunistic pathogens involved in many infections but they mainly affect the urinary tract of hospitalized, long-term catheterized patients. P. penneri rods produce a lot of virulence factors, among which the lipopolysaccharide seems to be the most interesting due to its structural and serological diversity. From the three LPS regions of P. penneri strains only the core region and O-specific polysaccharide (OPS) were structurally and serologically examined. P. penneri LPS core region is characterized by a common inner part representing the III glycoform and a diverse distal part (12 different structures). The P. penneri O-antigens contain sugar and non-sugar compounds and some of them rarely occur in nature. In both P. penneri LPS regions putative epitopes have been pointed out. Serospecificity of OPS allowed classifying many P. penneri isolates to different Proteus sp. O-serogroups, among which 12 contain P. penneri strains only. Copyright © 2013. Published by Elsevier Ltd.

  13. The effect of Zuccagnia punctata, an Argentine medicinal plant, on virulence factors from candida species.

    Science.gov (United States)

    Gabriela, Nuño; Rosa, Alberto María; Catiana, Zampini Iris; Soledad, Cuello; Mabel, Ordoñez Roxana; Esteban, Sayago Jorge; Veronica, Baroni; Daniel, Wunderlin; Ines, Isla María

    2014-07-01

    Zuccagnia punctata Cav. has been used as a traditional medicine in Argentina for the treatment of bacterial and fungal infections. In this study, we evaluated the ability of Z. punctata extract (ZpE) and compounds isolated from it to inhibit the growth and virulence factors of Candida species. ZpE showed inhibitory activity against planktonic cells of all assayed Candida species with MIC values of 400 microg/mL and with MFC values between 400 and 1,200 microg/mL. The principal identified compounds by HPLC-MS/MS and UV-VIS were chalcones (2',4'-dihydroxy-3'-methoxychalcone, 2',4'- dihydroxychalcone), flavones (galangin, 3,7-dihydroxyflavone and chrysin) and flavanones (naringenin, 7-hydroxyflavanone and pinocembrine). These compounds were more effective as inhibitors than the extracts upon biofilm formation as well as on preformed Candida biofilm and yeast germ tube formation. Furthermore, ZpE and chalcones are able to inhibit exoenzymes, which are responsible for the invasion mechanisms of the pathogens. All these effects could moderate colonization, thereby suppressing the pathogen invasive potential. Our results indicate that ZpE and chalcones could be used in antifungal therapy.

  14. The trans-sialidase, the major Trypanosoma cruzi virulence factor: Three decades of studies.

    Science.gov (United States)

    Freire-de-Lima, L; Fonseca, L M; Oeltmann, T; Mendonça-Previato, L; Previato, J O

    2015-11-01

    Chagas' disease is a potentially life-threatening disease caused by the protozoan parasite Trypanosoma cruzi. Since the description of Chagas'disease in 1909 extensive research has identified important events in the disease in order to understand the biochemical mechanism that modulates T. cruzi-host cell interactions and the ability of the parasite to ensure its survival in the infected host. Exactly 30 years ago, we presented evidence for the first time of a trans-sialidase activity in T. cruzi (T. cruzi-TS). This enzyme transfers sialic acid from the host glycoconjugates to the terminal β-galactopyranosyl residues of mucin-like molecules on the parasite's cell surface. Thenceforth, many articles have provided convincing data showing that T. cruzi-TS is able to govern relevant mechanisms involved in the parasite's survival in the mammalian host, such as invasion, escape from the phagolysosomal vacuole, differentiation, down-modulation of host immune responses, among others. The aim of this review is to cover the history of the discovery of T. cruzi-TS, as well as some well-documented biological effects encompassed by this parasite's virulence factor, an enzyme with potential attributes to become a drug target against Chagas disease. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. Myxoma virus M130R is a novel virulence factor required for lethal myxomatosis in rabbits.

    Science.gov (United States)

    Barrett, John W; Werden, Steven J; Wang, Fuan; McKillop, William M; Jimenez, June; Villeneuve, Danielle; McFadden, Grant; Dekaban, Gregory A

    2009-09-01

    Myxoma virus (MV) is a highly lethal, rabbit-specific poxvirus that induces a disease called myxomatosis in European rabbits. In an effort to understand the function of predicted immunomodulatory genes we have deleted various viral genes from MV and tested the ability of these knockout viruses to induce lethal myxomatosis. MV encodes a unique 15 kD cytoplasmic protein (M130R) that is expressed late (12h post infection) during infection. M130R is a non-essential gene for MV replication in rabbit, monkey or human cell lines. Construction of a targeted gene knockout virus (vMyx130KO) and infection of susceptible rabbits demonstrate that the M130R knockout virus is attenuated and that loss of M130R expression allows the rabbit host immune system to effectively respond to and control the lethal effects of MV. M130R expression is a bona fide poxviral virulence factor necessary for full and lethal development of myxomatosis.

  16. Effect of virulence factors on the photodynamic inactivation of Cryptococcus neoformans.

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    Renato A Prates

    Full Text Available Opportunistic fungal pathogens may cause an array of superficial infections or serious invasive infections, especially in immunocompromised patients. Cryptococcus neoformans is a pathogen causing cryptococcosis in HIV/AIDS patients, but treatment is limited due to the relative lack of potent antifungal agents. Photodynamic inactivation (PDI uses the combination of non-toxic dyes called photosensitizers and harmless visible light, which produces singlet oxygen and other reactive oxygen species that produce cell inactivation and death. We report the use of five structurally unrelated photosensitizers (methylene blue, Rose Bengal, selenium derivative of a Nile blue dye, a cationic fullerene and a conjugate between poly-L-lysine and chlorin(e6 combined with appropriate wavelengths of light to inactivate C. neoformans. Mutants lacking capsule and laccase, and culture conditions that favoured melanin production were used to probe the mechanisms of PDI and the effect of virulence factors. The presence of cell wall, laccase and melanin tended to protect against PDI, but the choice of the appropriate photosensitizers and dosimetry was able to overcome this resistance.

  17. Relationship between virulence factors, resistance to antibiotics and phylogenetic groups of uropathogenic Escherichia coli in two locations in Mexico.

    Science.gov (United States)

    Miranda-Estrada, Laura Iveth; Ruíz-Rosas, María; Molina-López, José; Parra-Rojas, Isela; González-Villalobos, Edgar; Castro-Alarcón, Natividad

    Escherichia coli is the major causative agent of urinary tract infections (UTI), and virulence factors are responsible for the severity of these emerging infections. The aim of this study was to evaluate the relationship between virulence determinants and antibiotic susceptibility with phylogenetic groups of E.coli isolates of UTI in two locations in Mexico. An analysis was performed on 50 isolates of E.coli from the centre of the country and 57 from a town in the southwest. The isolates were characterized by phenotype (serotyping assays, in vitro adhesion, biofilm formation, production of haemolysin, and antibiotic susceptibility) and genotype (phylogenetic groups and virulence genes). In the centre of the country location the phylogenetic group B2 (60%) and F (12%) were significantly more prevalent and had a higher frequency of genes, fimH (96%), iutA (66%), sat (36%), compared to the southwest location, where the group A (35%) and B1 (21%) were significantly predominant and had fewer virulence genes. About one-fifth (21.5%) of all isolates belonged to the O25-ST131 group. Haemolysin and biofilm producing strains were significantly higher in the southwest location. Resistance to ampicillin (92.5%), tetracycline (76.6%), and trimethoprim/sulfamethoxazole (70.1%) were the most common in both groups. The phylogenetic group, virulence factors, and antibiotic susceptibility of the E.coli that causes UTI in the community, varies significantly among the Mexican populations studied. Phylogenetic groups A and B1 may be multidrug resistant and have the ability to produce UTI. Copyright © 2016 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

  18. The NlpD lipoprotein is a novel Yersinia pestis virulence factor essential for the development of plague.

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    Avital Tidhar

    Full Text Available Yersinia pestis is the causative agent of plague. Previously we have isolated an attenuated Y. pestis transposon insertion mutant in which the pcm gene was disrupted. In the present study, we investigated the expression and the role of pcm locus genes in Y. pestis pathogenesis using a set of isogenic surE, pcm, nlpD and rpoS mutants of the fully virulent Kimberley53 strain. We show that in Y. pestis, nlpD expression is controlled from elements residing within the upstream genes surE and pcm. The NlpD lipoprotein is the only factor encoded from the pcm locus that is essential for Y. pestis virulence. A chromosomal deletion of the nlpD gene sequence resulted in a drastic reduction in virulence to an LD(50 of at least 10(7 cfu for subcutaneous and airway routes of infection. The mutant was unable to colonize mouse organs following infection. The filamented morphology of the nlpD mutant indicates that NlpD is involved in cell separation; however, deletion of nlpD did not affect in vitro growth rate. Trans-complementation experiments with the Y. pestis nlpD gene restored virulence and all other phenotypic defects. Finally, we demonstrated that subcutaneous administration of the nlpD mutant could protect animals against bubonic and primary pneumonic plague. Taken together, these results demonstrate that Y. pestis NlpD is a novel virulence factor essential for the development of bubonic and pneumonic plague. Further, the nlpD mutant is superior to the EV76 prototype live vaccine strain in immunogenicity and in conferring effective protective immunity. Thus it could serve as a basis for a very potent live vaccine against bubonic and pneumonic plague.

  19. Secretion of the chlamydial virulence factor CPAF requires the Sec-dependent pathway

    Science.gov (United States)

    Chen, Ding; Lei, Lei; Lu, Chunxue; Flores, Rhonda; DeLisa, Matthew P.; Roberts, Tucker C.; Romesberg, Floyd E.; Zhong, Guangming

    2010-01-01

    The chlamydial protease/proteasome-like activity factor (CPAF) is secreted into the host cytosol to degrade various host factors that benefit chlamydial intracellular survival. Although the full-length CPAF is predicted to contain a putative signal peptide at its N terminus, the secretion pathway of CPAF is still unknown. Here, we have provided experimental evidence that the N-terminal sequence covering the M1–G31 region was cleaved from CPAF during chlamydial infection. The CPAF N-terminal sequence, when expressed in a phoA gene fusion construct, was able to direct the export of the mature PhoA protein across the inner membrane of wild-type Escherichia coli. However, E. coli mutants deficient in SecB failed to support the CPAF signal-peptide-directed secretion of PhoA. Since native PhoA secretion was known to be independent of SecB, this SecB dependence must be rendered by the CPAF leader peptide. Furthermore, lack of SecY function also blocked the CPAF signal-peptide-directed secretion of PhoA. Most importantly, CPAF secretion into the host cell cytosol during chlamydial infection was selectively inhibited by an inhibitor specifically targeting type I signal peptidase but not by a type III secretion-system-specific inhibitor. Together, these observations have demonstrated that the chlamydial virulence factor CPAF relies on Sec-dependent transport for crossing the chlamydial inner membrane, which has provided essential information for further delineating the pathways of CPAF action and understanding chlamydial pathogenic mechanisms. PMID:20522495

  20. Transcription factor Amr1 induces melanin biosynthesis and suppresses virulence in Alternaria brassicicola.

    Science.gov (United States)

    Cho, Yangrae; Srivastava, Akhil; Ohm, Robin A; Lawrence, Christopher B; Wang, Koon-Hui; Grigoriev, Igor V; Marahatta, Sharadchandra P

    2012-01-01

    Alternaria brassicicola is a successful saprophyte and necrotrophic plant pathogen. Several A. brassicicola genes have been characterized as affecting pathogenesis of Brassica species. To study regulatory mechanisms of pathogenesis, we mined 421 genes in silico encoding putative transcription factors in a machine-annotated, draft genome sequence of A. brassicicola. In this study, targeted gene disruption mutants for 117 of the transcription factor genes were produced and screened. Three of these genes were associated with pathogenesis. Disruption mutants of one gene (AbPacC) were nonpathogenic and another gene (AbVf8) caused lesions less than half the diameter of wild-type lesions. Unexpectedly, mutants of the third gene, Amr1, caused lesions with a two-fold larger diameter than the wild type and complementation mutants. Amr1 is a homolog of Cmr1, a transcription factor that regulates melanin biosynthesis in several fungi. We created gene deletion mutants of Δamr1 and characterized their phenotypes. The Δamr1 mutants used pectin as a carbon source more efficiently than the wild type, were melanin-deficient, and more sensitive to UV light and glucanase digestion. The AMR1 protein was localized in the nuclei of hyphae and in highly melanized conidia during the late stage of plant pathogenesis. RNA-seq analysis revealed that three genes in the melanin biosynthesis pathway, along with the deleted Amr1 gene, were expressed at low levels in the mutants. In contrast, many hydrolytic enzyme-coding genes were expressed at higher levels in the mutants than in the wild type during pathogenesis. The results of this study suggested that a gene important for survival in nature negatively affected virulence, probably by a less efficient use of plant cell-wall materials. We speculate that the functions of the Amr1 gene are important to the success of A. brassicicola as a competitive saprophyte and plant parasite.

  1. Transcription factor Amr1 induces melanin biosynthesis and suppresses virulence in Alternaria brassicicola.

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    Yangrae Cho

    Full Text Available Alternaria brassicicola is a successful saprophyte and necrotrophic plant pathogen. Several A. brassicicola genes have been characterized as affecting pathogenesis of Brassica species. To study regulatory mechanisms of pathogenesis, we mined 421 genes in silico encoding putative transcription factors in a machine-annotated, draft genome sequence of A. brassicicola. In this study, targeted gene disruption mutants for 117 of the transcription factor genes were produced and screened. Three of these genes were associated with pathogenesis. Disruption mutants of one gene (AbPacC were nonpathogenic and another gene (AbVf8 caused lesions less than half the diameter of wild-type lesions. Unexpectedly, mutants of the third gene, Amr1, caused lesions with a two-fold larger diameter than the wild type and complementation mutants. Amr1 is a homolog of Cmr1, a transcription factor that regulates melanin biosynthesis in several fungi. We created gene deletion mutants of Δamr1 and characterized their phenotypes. The Δamr1 mutants used pectin as a carbon source more efficiently than the wild type, were melanin-deficient, and more sensitive to UV light and glucanase digestion. The AMR1 protein was localized in the nuclei of hyphae and in highly melanized conidia during the late stage of plant pathogenesis. RNA-seq analysis revealed that three genes in the melanin biosynthesis pathway, along with the deleted Amr1 gene, were expressed at low levels in the mutants. In contrast, many hydrolytic enzyme-coding genes were expressed at higher levels in the mutants than in the wild type during pathogenesis. The results of this study suggested that a gene important for survival in nature negatively affected virulence, probably by a less efficient use of plant cell-wall materials. We speculate that the functions of the Amr1 gene are important to the success of A. brassicicola as a competitive saprophyte and plant parasite.

  2. Transcription Factor Amr1 Induces Melanin Biosynthesis and Suppresses Virulence in Alternaria brassicicola

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    Cho, Yangrae; Srivastava, Akhil; Ohm, Robin A.; Lawrence, Christopher B.; Wang, Koon-Hui; Grigoriev, Igor V.; Marahatta, Sharadchandra P.

    2012-05-01

    Alternaria brassicicola is a successful saprophyte and necrotrophic plant pathogen. Several A. brassicicola genes have been characterized as affecting pathogenesis of Brassica species. To study regulatory mechanisms of pathogenesis, we mined 421 genes in silico encoding putative transcription factors in a machine-annotated, draft genome sequence of A. brassicicola. In this study, targeted gene disruption mutants for 117 of the transcription factor genes were produced and screened. Three of these genes were associated with pathogenesis. Disruption mutants of one gene (AbPacC) were nonpathogenic and another gene (AbVf8) caused lesions less than half the diameter of wild-type lesions. Unexpectedly, mutants of the third gene, Amr1, caused lesions with a two-fold larger diameter than the wild type and complementation mutants. Amr1 is a homolog of Cmr1, a transcription factor that regulates melanin biosynthesis in several fungi. We created gene deletion mutants of ?amr1 and characterized their phenotypes. The ?amr1 mutants used pectin as a carbon source more efficiently than the wild type, were melanin-deficient, and more sensitive to UV light and glucanase digestion. The AMR1 protein was localized in the nuclei of hyphae and in highly melanized conidia during the late stage of plant pathogenesis. RNA-seq analysis revealed that three genes in the melanin biosynthesis pathway, along with the deleted Amr1 gene, were expressed at low levels in the mutants. In contrast, many hydrolytic enzyme-coding genes were expressed at higher levels in the mutants than in the wild type during pathogenesis. The results of this study suggested that a gene important for survival in nature negatively affected virulence, probably by a less efficient use of plant cell-wall materials. We speculate that the functions of the Amr1 gene are important to the success of A. brassicicola as a competitive saprophyte and plant parasite.

  3. Unfolded Protein Response (UPR Regulator Cib1 Controls Expression of Genes Encoding Secreted Virulence Factors in Ustilago maydis.

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    Martin Hampel

    Full Text Available The unfolded protein response (UPR, a conserved eukaryotic signaling pathway to ensure protein homeostasis in the endoplasmic reticulum (ER, coordinates biotrophic development in the corn smut fungus Ustilago maydis. Exact timing of UPR activation is required for virulence and presumably connected to the elevated expression of secreted effector proteins during infection of the host plant Zea mays. In the baker's yeast Saccharomyces cerevisiae, expression of UPR target genes is induced upon binding of the central regulator Hac1 to unfolded protein response elements (UPREs in their promoters. While a role of the UPR in effector secretion has been described previously, we investigated a potential UPR-dependent regulation of genes encoding secreted effector proteins. In silico prediction of UPREs in promoter regions identified the previously characterized effector genes pit2 and tin1-1, as bona fide UPR target genes. Furthermore, direct binding of the Hac1-homolog Cib1 to the UPRE containing promoter fragments of both genes was confirmed by quantitative chromatin immunoprecipitation (qChIP analysis. Targeted deletion of the UPRE abolished Cib1-dependent expression of pit2 and significantly affected virulence. Furthermore, ER stress strongly increased Pit2 expression and secretion. This study expands the role of the UPR as a signal hub in fungal virulence and illustrates, how biotrophic fungi can coordinate cellular physiology, development and regulation of secreted virulence factors.

  4. Unfolded Protein Response (UPR) Regulator Cib1 Controls Expression of Genes Encoding Secreted Virulence Factors in Ustilago maydis.

    Science.gov (United States)

    Hampel, Martin; Jakobi, Mareike; Schmitz, Lara; Meyer, Ute; Finkernagel, Florian; Doehlemann, Gunther; Heimel, Kai

    2016-01-01

    The unfolded protein response (UPR), a conserved eukaryotic signaling pathway to ensure protein homeostasis in the endoplasmic reticulum (ER), coordinates biotrophic development in the corn smut fungus Ustilago maydis. Exact timing of UPR activation is required for virulence and presumably connected to the elevated expression of secreted effector proteins during infection of the host plant Zea mays. In the baker's yeast Saccharomyces cerevisiae, expression of UPR target genes is induced upon binding of the central regulator Hac1 to unfolded protein response elements (UPREs) in their promoters. While a role of the UPR in effector secretion has been described previously, we investigated a potential UPR-dependent regulation of genes encoding secreted effector proteins. In silico prediction of UPREs in promoter regions identified the previously characterized effector genes pit2 and tin1-1, as bona fide UPR target genes. Furthermore, direct binding of the Hac1-homolog Cib1 to the UPRE containing promoter fragments of both genes was confirmed by quantitative chromatin immunoprecipitation (qChIP) analysis. Targeted deletion of the UPRE abolished Cib1-dependent expression of pit2 and significantly affected virulence. Furthermore, ER stress strongly increased Pit2 expression and secretion. This study expands the role of the UPR as a signal hub in fungal virulence and illustrates, how biotrophic fungi can coordinate cellular physiology, development and regulation of secreted virulence factors.

  5. The Fish Pathogen Vibrio vulnificus Biotype 2: Epidemiology, Phylogeny, and Virulence Factors Involved in Warm-Water Vibriosis.

    Science.gov (United States)

    Amaro, Carmen; Sanjuán, Eva; Fouz, Belén; Pajuelo, David; Lee, Chung-Te; Hor, Lien-I; Barrera, Rodolfo

    2015-06-01

    Vibrio vulnificus biotype 2 is the etiological agent of warm-water vibriosis, a disease that affects eels and other teleosts, especially in fish farms. Biotype 2 is polyphyletic and probably emerged from aquatic bacteria by acquisition of a transferable virulence plasmid that encodes resistance to innate immunity of eels and other teleosts. Interestingly, biotype 2 comprises a zoonotic clonal complex designated as serovar E that has extended worldwide. One of the most interesting virulence factors produced by serovar E is RtxA13, a multifunctional protein that acts as a lethal factor for fish, an invasion factor for mice, and a survival factor outside the host. Two practically identical copies of rtxA13 are present in all biotype 2 strains regardless of the serovar, one in the virulence plasmid and the other in chromosome II. The plasmid also contains other genes involved in survival and growth in eel blood: vep07, a gene for an outer membrane (OM) lipoprotein involved in resistance to eel serum and vep20, a gene for an OM receptor specific for eel-transferrin and, probably, other related fish transferrins. All the three genes are highly conserved within biotype 2, which suggests that they are under a strong selective pressure. Interestingly, the three genes are related with transferable plasmids, which emphasizes the role of horizontal gene transfer in the evolution of V. vulnificus in nutrient-enriched aquatic environments, such as fish farms.

  6. Profiling antibody responses to infections by Chlamydia abortus enables identification of potential virulence factors and candidates for serodiagnosis.

    Directory of Open Access Journals (Sweden)

    Vera Forsbach-Birk

    Full Text Available Enzootic abortion of ewes (EAE due to infection with the obligate intracellular pathogen Chlamydia (C. abortus is an important zoonosis leading to considerable economic loss to agriculture worldwide. The pathogen can be transmitted to humans and may lead to serious infection in pregnant women. Knowledge about epidemiology, clinical course and transmission to humans is hampered by the lack of reliable diagnostic tools. Immunoreactive proteins, which are expressed in infected animals and humans, may serve as novel candidates for diagnostic marker proteins and represent putative virulence factors. In order to broaden the spectrum of immunogenic C. abortus proteins we applied 2D immunoblot analysis and screening of an expression library using human and animal sera. We have identified 48 immunoreactive proteins representing potential diagnostic markers and also putative virulence factors, such as CAB080 (homologue of the "macrophage infectivity potentiator", MIP, CAB167 (homologue of the "translocated actin recruitment protein", TARP, CAB712 (homologue of the "chlamydial protease-like activity factor", CPAF, CAB776 (homologue of the "Polymorphic membrane protein D", PmpD, and the "hypothetical proteins" CAB063, CAB408 and CAB821, which are predicted to be type III secreted. We selected two putative virulence factors for further characterization, i.e. CAB080 (cMIP and CAB063, and studied their expression profiles at transcript and protein levels. Analysis of the subcellular localization of both proteins throughout the developmental cycle revealed CAB063 being the first C. abortus protein shown to be translocated to the host cell nucleus.

  7. Two Nucleolar Proteins, GDP1 and OLI2, Function As Ribosome Biogenesis Factors and Are Preferentially Involved in Promotion of Leaf Cell Proliferation without Strongly Affecting Leaf Adaxial–Abaxial Patterning in Arabidopsis thaliana

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    Koji Kojima

    2018-01-01

    Full Text Available Leaf abaxial–adaxial patterning is dependent on the mutual repression of leaf polarity genes expressed either adaxially or abaxially. In Arabidopsis thaliana, this process is strongly affected by mutations in ribosomal protein genes and in ribosome biogenesis genes in a sensitized genetic background, such as asymmetric leaves2 (as2. Most ribosome-related mutants by themselves do not show leaf abaxialization, and one of their typical phenotypes is the formation of pointed rather than rounded leaves. In this study, we characterized two ribosome-related mutants to understand how ribosome biogenesis is linked to several aspects of leaf development. Previously, we isolated oligocellula2 (oli2 which exhibits the pointed-leaf phenotype and has a cell proliferation defect. OLI2 encodes a homolog of Nop2 in Saccharomyces cerevisiae, a ribosome biogenesis factor involved in pre-60S subunit maturation. In this study, we found another pointed-leaf mutant that carries a mutation in a gene encoding an uncharacterized protein with a G-patch domain. Similar to oli2, this mutant, named g-patch domain protein1 (gdp1, has a reduced number of leaf cells. In addition, gdp1 oli2 double mutants showed a strong genetic interaction such that they synergistically impaired cell proliferation in leaves and produced markedly larger cells. On the other hand, they showed additive phenotypes when combined with several known ribosomal protein mutants. Furthermore, these mutants have a defect in pre-rRNA processing. GDP1 and OLI2 are strongly expressed in tissues with high cell proliferation activity, and GDP1-GFP and GFP-OLI2 are localized in the nucleolus. These results suggest that OLI2 and GDP1 are involved in ribosome biogenesis. We then examined the effects of gdp1 and oli2 on adaxial–abaxial patterning by crossing them with as2. Interestingly, neither gdp1 nor oli2 strongly enhanced the leaf polarity defect of as2. Similar results were obtained with as2 gdp1 oli2

  8. Phage-mediated dissemination of virulence factors in pathogenic bacteria facilitated by antibiotic growth promoters in animals: a perspective.

    Science.gov (United States)

    Tamang, Migma Dorji; Sunwoo, Hoon; Jeon, Byeonghwa

    2017-11-29

    Addition of sub-therapeutic antibiotics to the feed of food-producing animals for growth promotion and disease prevention has become a common agricultural practice in many countries. The emergence of antibiotic-resistant pathogens is a looming concern associated with the use of antibiotic growth promoters (AGPs) around the world. In addition, some studies have shown that AGPs may not only affect antibiotic resistance but may also stimulate the dissemination of virulence factors via bacteriophages. Although only a few studies are currently available in the literature regarding this topic, in this article we endeavor to provide a perspective about how AGPs would impact the transmission of virulence factors by horizontal gene transfer via phages in a few pathogenic bacterial species significant to livestock production.

  9. The phytoplasmal virulence factor TENGU causes plant sterility by downregulating of the jasmonic acid and auxin pathways.

    Science.gov (United States)

    Minato, Nami; Himeno, Misako; Hoshi, Ayaka; Maejima, Kensaku; Komatsu, Ken; Takebayashi, Yumiko; Kasahara, Hiroyuki; Yusa, Akira; Yamaji, Yasuyuki; Oshima, Kenro; Kamiya, Yuji; Namba, Shigetou

    2014-12-10

    Despite plants infected by pathogens are often unable to produce offspring, it remains unclear how sterility is induced in host plants. In this study, we demonstrate that TENGU, a phytoplasmal virulence peptide known as a dwarfism inducer, acts as an inducer of sterility. Transgenic expression of TENGU induced both male and female sterility in Arabidopsis thaliana flowers similar to those observed in double knockout mutants of auxin response factor 6 (ARF6) and ARF8, which are known to regulate floral development in a jasmonic acid (JA)-dependent manner. Transcripts of ARF6 and ARF8 were significantly decreased in both tengu-transgenic and phytoplasma-infected plants. Furthermore, JA and auxin levels were actually decreased in tengu-transgenic buds, suggesting that TENGU reduces the endogenous levels of phytohormones by repressing ARF6 and ARF8, resulting in impaired flower maturation. TENGU is the first virulence factor with the effects on plant reproduction by perturbation of phytohormone signaling.

  10. Helicobacter pylori virulence factors affecting gastric proton pump expression and acid secretion.

    Science.gov (United States)

    Hammond, Charles E; Beeson, Craig; Suarez, Giovanni; Peek, Richard M; Backert, Steffen; Smolka, Adam J

    2015-08-01

    Acute Helicobacter pylori infection of gastric epithelial cells and human gastric biopsies represses H,K-ATPase α subunit (HKα) gene expression and inhibits acid secretion, causing transient hypochlorhydria and supporting gastric H. pylori colonization. Infection by H. pylori strains deficient in the cag pathogenicity island (cag PAI) genes cagL, cagE, or cagM, which do not transfer CagA into host cells or induce interleukin-8 secretion, does not inhibit HKα expression, nor does a cagA-deficient strain that induces IL-8. To test the hypothesis that virulence factors other than those mediating CagA translocation or IL-8 induction participate in HKα repression by activating NF-κB, AGS cells transfected with HKα promoter-Luc reporter constructs containing an intact or mutated NF-κB binding site were infected with wild-type H. pylori strain 7.13, isogenic mutants lacking cag PAI genes responsible for CagA translocation and/or IL-8 induction (cagA, cagζ, cagε, cagZ, and cagβ), or deficient in genes encoding two peptidoglycan hydrolases (slt and cagγ). H. pylori-induced AGS cell HKα promoter activities, translocated CagA, and IL-8 secretion were measured by luminometry, immunoblotting, and ELISA, respectively. Human gastric biopsy acid secretion was measured by microphysiometry. Taken together, the data showed that HKα repression is independent of IL-8 expression, and that CagA translocation together with H. pylori transglycosylases encoded by slt and cagγ participate in NF-κB-dependent HKα repression and acid inhibition. The findings are significant because H. pylori factors other than CagA and IL-8 secretion are now implicated in transient hypochlorhydria which facilitates gastric colonization and potential triggering of epithelial progression to neoplasia. Copyright © 2015 the American Physiological Society.

  11. Epoxide-mediated differential packaging of Cif and other virulence factors into outer membrane vesicles.

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    Ballok, Alicia E; Filkins, Laura M; Bomberger, Jennifer M; Stanton, Bruce A; O'Toole, George A

    2014-10-01

    Pseudomonas aeruginosa produces outer membrane vesicles (OMVs) that contain a number of secreted bacterial proteins, including phospholipases, alkaline phosphatase, and the CFTR inhibitory factor (Cif). Previously, Cif, an epoxide hydrolase, was shown to be regulated at the transcriptional level by epoxides, which serve as ligands of the repressor, CifR. Here, we tested whether epoxides have an effect on Cif levels in OMVs. We showed that growth of P. aeruginosa in the presence of specific epoxides but not a hydrolysis product increased Cif packaging into OMVs in a CifR-independent fashion. The outer membrane protein, OprF, was also increased under these conditions, but alkaline phosphatase activity was not significantly altered. Additionally, we demonstrated that OMV shape and density were affected by epoxide treatment, with two distinct vesicle fractions present when cells were treated with epibromohydrin (EBH), a model epoxide. Vesicles isolated from the two density fractions exhibited different protein profiles in Western blotting and silver staining. We have shown that a variety of clinically or host-relevant treatments, including antibiotics, also alter the proteins packaged in OMVs. Proteomic analysis of purified OMVs followed by an analysis of transposon mutant OMVs yielded mutants with altered vesicle packaging. Finally, epithelial cell cytotoxicity was reduced in the vesicles formed in the presence of EBH, suggesting that this epoxide alters the function of the OMVs. Our data support a model whereby clinically or host-relevant signals mediate differential packaging of virulence factors in OMVs, which results in functional consequences for host-pathogen interactions. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  12. Virulence factors, antibiotic resistance genes and genetic relatedness of commensal Escherichia coli isolates from dogs and their owners.

    Science.gov (United States)

    Derakhshandeh, Abdollah; Eraghi, Vida; Boroojeni, Azar Motamedi; Niaki, Malihe Akbarzadeh; Zare, Sahar; Naziri, Zahra

    2018-01-30

    Escherichia coli (E. coli) is a normal flora of gastrointestinal tracts of humans and warm-blooded animals including dogs that has close vicinity with humans. Because the inter-species transmission of E. coli between pets and human beings, within a household, obtaining more information about the epidemiology, genetics, virulence factors, and antibiotic resistance of E. coli from dogs and their owners will help to control the inter-species transmission and treatment of E. coli infections. In this study we characterize and compare the antibiotic resistance and virulence profiles of fecal E. coli isolates from dogs and their owners. A total of 149 commensal E. coli isolates comprised 62 isolates from dogs, 56 isolates from their owners and 31 isolates from humans with no pet as control were collected. Extracted DNA was assessed for the presence of antibiotic resistance genes cmlA (chloramphenicol), sulI (sulfamethoxazole), floR (florfenicol) and blaCTX-M1 (cefotaxime) and virulence genes (papA, ompT, hlyD, traT, tsh and cnf1). To determine the extent of genetic relatedness of isolates, RAPD-PCR was performed. sulI and traT genes were the most dominant resistance profile and the most prevalent virulence gene in all groups, respectively, while hlyD had the lowest frequency among investigated virulence genes. Based on RAPD-PCR analysis clonal sharing between dogs and their owners were observed in 2/28 (7.1%) potential within-household clone-sharing pairs. Allowing dog to lick on owner's face, dog sex (female dogs), dog's sexual status (intact dogs) and times of disposing the feces (≥twice a day) were associated with a higher percentage of RAPD profile similarity (P coli from dogs to their owners. But in two households, there were relationship between isolates from dogs and their owners. Copyright © 2018. Published by Elsevier Ltd.

  13. A novel line immunoassay based on recombinant virulence factors enables highly specific and sensitive serologic diagnosis of Helicobacter pylori infection.

    Science.gov (United States)

    Formichella, Luca; Romberg, Laura; Bolz, Christian; Vieth, Michael; Geppert, Michael; Göttner, Gereon; Nölting, Christina; Walter, Dirk; Schepp, Wolfgang; Schneider, Arne; Ulm, Kurt; Wolf, Petra; Busch, Dirk H; Soutschek, Erwin; Gerhard, Markus

    2013-11-01

    Helicobacter pylori colonizes half of the world's population, and infection can lead to ulcers, gastric cancer, and mucosa-associated lymphoid tissue (MALT) lymphoma. Serology is the only test applicable for large-scale, population-based screening, but current tests are hampered by a lack of sensitivity and/or specificity. Also, no serologic test allows the differentiation of type I and type II strains, which is important for predicting the clinical outcome. H. pylori virulence factors have been associated with disease, but direct assessment of virulence factors requires invasive methods to obtain gastric biopsy specimens. Our work aimed at the development of a highly sensitive and specific, noninvasive serologic test to detect immune responses to important H. pylori virulence factors. This line immunoassay system (recomLine) is based on recombinant proteins. For this assay, six highly immunogenic virulence factors (CagA, VacA, GroEL, gGT, HcpC, and UreA) were expressed in Escherichia coli, purified, and immobilized to nitrocellulose membranes to detect serological immune responses in patient's sera. For the validation of the line assay, a cohort of 500 patients was screened, of which 290 (58.0%) were H. pylori negative and 210 (42.0%) were positive by histology. The assay showed sensitivity and specificity of 97.6% and 96.2%, respectively, compared to histology. In direct comparison to lysate blotting and enzyme-linked immunosorbent assay (ELISA), the recomLine assay had increased discriminatory power. For the assessment of individual risk for gastrointestinal disease, the test must be validated in a larger and defined patient cohort. Taking the data together, the recomLine assay provides a valuable tool for the diagnosis of H. pylori infection.

  14. Virulence Factors of Pseudomonas aeruginosa Induce Both the Unfolded Protein and Integrated Stress Responses in Airway Epithelial Cells.

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    Emily F A van 't Wout

    2015-06-01

    Full Text Available Pseudomonas aeruginosa infection can be disastrous in chronic lung diseases such as cystic fibrosis and chronic obstructive pulmonary disease. Its toxic effects are largely mediated by secreted virulence factors including pyocyanin, elastase and alkaline protease (AprA. Efficient functioning of the endoplasmic reticulum (ER is crucial for cell survival and appropriate immune responses, while an excess of unfolded proteins within the ER leads to "ER stress" and activation of the "unfolded protein response" (UPR. Bacterial infection and Toll-like receptor activation trigger the UPR most likely due to the increased demand for protein folding of inflammatory mediators. In this study, we show that cell-free conditioned medium of the PAO1 strain of P. aeruginosa, containing secreted virulence factors, induces ER stress in primary bronchial epithelial cells as evidenced by splicing of XBP1 mRNA and induction of CHOP, GRP78 and GADD34 expression. Most aspects of the ER stress response were dependent on TAK1 and p38 MAPK, except for the induction of GADD34 mRNA. Using various mutant strains and purified virulence factors, we identified pyocyanin and AprA as inducers of ER stress. However, the induction of GADD34 was mediated by an ER stress-independent integrated stress response (ISR which was at least partly dependent on the iron-sensing eIF2α kinase HRI. Our data strongly suggest that this increased GADD34 expression served to protect against Pseudomonas-induced, iron-sensitive cell cytotoxicity. In summary, virulence factors from P. aeruginosa induce ER stress in airway epithelial cells and also trigger the ISR to improve cell survival of the host.

  15. Genomes and virulence factors of novel bacterial pathogens causing bleaching disease in the marine red alga Delisea pulchra.

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    Neil Fernandes

    Full Text Available Nautella sp. R11, a member of the marine Roseobacter clade, causes a bleaching disease in the temperate-marine red macroalga, Delisea pulchra. To begin to elucidate the molecular mechanisms underpinning the ability of Nautella sp. R11 to colonize, invade and induce bleaching of D. pulchra, we sequenced and analyzed its genome. The genome encodes several factors such as adhesion mechanisms, systems for the transport of algal metabolites, enzymes that confer resistance to oxidative stress, cytolysins, and global regulatory mechanisms that may allow for the switch of Nautella sp. R11 to a pathogenic lifestyle. Many virulence effectors common in phytopathogenic bacteria are also found in the R11 genome, such as the plant hormone indole acetic acid, cellulose fibrils, succinoglycan and nodulation protein L. Comparative genomics with non-pathogenic Roseobacter strains and a newly identified pathogen, Phaeobacter sp. LSS9, revealed a patchy distribution of putative virulence factors in all genomes, but also led to the identification of a quorum sensing (QS dependent transcriptional regulator that was unique to pathogenic Roseobacter strains. This observation supports the model that a combination of virulence factors and QS-dependent regulatory mechanisms enables indigenous members of the host alga's epiphytic microbial community to switch to a pathogenic lifestyle, especially under environmental conditions when innate host defence mechanisms are compromised.

  16. Inhibitory effect of Thymus vulgaris and Origanum vulgare essential oils on virulence factors of phytopathogenic Pseudomonas syringae strains.

    Science.gov (United States)

    Carezzano, M E; Sotelo, J P; Primo, E; Reinoso, E B; Paletti Rovey, M F; Demo, M S; Giordano, W F; Oliva, M de Las M

    2017-07-01

    Pseudomonas syringae is a phytopathogenic bacterium that causes lesions in leaves during the colonisation process. The damage is associated with production of many virulence factors, such as biofilm and phytotoxins. The essential oils of Thymus vulgaris (thyme) and Origanum vulgare (oregano) have been demonstrated to inhibit P. syringae. The aim of this study was to investigate the effects of T. vulgaris and O. vulgare essential oils on production of virulence factors of phytopathogenic P. syringae strains, including anti-biofilm and anti-toxins activities. The broth microdilution method was used for determination of MIC and biofilm inhibition assays. Coronatine, syringomycin and tabtoxin were pheno- and genotypically evaluated. Both oils showed good inhibitory activity against P. syringae, with MIC values from 1.43 to 11.5 mg·ml -1 for thyme and 5.8 to 11.6 mg·ml -1 for oregano. Biofilm formation, production of coronatine, syringomycin and tabtoxin were inhibited by thyme and oregano essential oil in most strains. The results presented here are promising, demonstrating the bactericidal activity and reduction of virulence factor production after treatment with thyme and oregano oil, providing insight into how they exert their antibacterial activity. These natural products could be considered in the future for the control of diseases caused by P. syringae. © 2017 German Botanical Society and The Royal Botanical Society of the Netherlands.

  17. Genomes and virulence factors of novel bacterial pathogens causing bleaching disease in the marine red alga Delisea pulchra.

    Science.gov (United States)

    Fernandes, Neil; Case, Rebecca J; Longford, Sharon R; Seyedsayamdost, Mohammad R; Steinberg, Peter D; Kjelleberg, Staffan; Thomas, Torsten

    2011-01-01

    Nautella sp. R11, a member of the marine Roseobacter clade, causes a bleaching disease in the temperate-marine red macroalga, Delisea pulchra. To begin to elucidate the molecular mechanisms underpinning the ability of Nautella sp. R11 to colonize, invade and induce bleaching of D. pulchra, we sequenced and analyzed its genome. The genome encodes several factors such as adhesion mechanisms, systems for the transport of algal metabolites, enzymes that confer resistance to oxidative stress, cytolysins, and global regulatory mechanisms that may allow for the switch of Nautella sp. R11 to a pathogenic lifestyle. Many virulence effectors common in phytopathogenic bacteria are also found in the R11 genome, such as the plant hormone indole acetic acid, cellulose fibrils, succinoglycan and nodulation protein L. Comparative genomics with non-pathogenic Roseobacter strains and a newly identified pathogen, Phaeobacter sp. LSS9, revealed a patchy distribution of putative virulence factors in all genomes, but also led to the identification of a quorum sensing (QS) dependent transcriptional regulator that was unique to pathogenic Roseobacter strains. This observation supports the model that a combination of virulence factors and QS-dependent regulatory mechanisms enables indigenous members of the host alga's epiphytic microbial community to switch to a pathogenic lifestyle, especially under environmental conditions when innate host defence mechanisms are compromised.

  18. The 50kDa metalloproteinase TvMP50 is a zinc-mediated Trichomonas vaginalis virulence factor.

    Science.gov (United States)

    Puente-Rivera, Jonathan; Villalpando, José Luis; Villalobos-Osnaya, Alma; Vázquez-Carrillo, Laura Isabel; León-Ávila, Gloria; Ponce-Regalado, María Dolores; López-Camarillo, César; Elizalde-Contreras, Jose Miguel; Ruiz-May, Eliel; Arroyo, Rossana; Alvarez-Sánchez, María Elizbeth

    2017-10-01

    Trichomonas vaginalis is a protozoan parasite that can adapt to the trichomonicidal Zn2+ concentrations of the male urogenital tract microenvironment. This adaptation is mediated by molecular mechanisms, including proteinase expression, that are regulated by cations such as Zn2+. Herein, we characterized the previously identified 50kDa metalloproteinase aminopeptidase P (M24 family) member TvMP50 as a new Zn2+-mediated parasite virulence factor. Quantitative RT-PCR and indirect immunofluorescence assays corroborated the positive regulation of both mp50 gene expression and native TvMP50 protein overexpression in the cytoplasm and secretion products of parasites grown in the presence of Zn2+. Furthermore, this active metalloproteinase was characterized as a new virulence factor by assaying cytotoxicity toward prostatic DU145 cell monolayers as well as the inhibition of parasite and secreted soluble protein proteolytic activity in the 50kDa proteolytic region by the specific metalloproteinase inhibitor 1,10-phenanthroline and the chelating agents EDTA and EGTA. Parasite and secreted soluble protein cytotoxicity toward DU145 cells were reduced by treatment with an α-rTvMP50 polyclonal antibody. Our results show that the metalloproteinase TvMP50 is a new virulence factor modulated by Zn2+, which is present during male trichomoniasis, possibly explaining T. vaginalis survival even within the adverse conditions of the male urogenital microenvironment. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. The effect of burdock leaf fraction on adhesion, biofilm formation, quorum sensing and virulence factors of Pseudomonas aeruginosa.

    Science.gov (United States)

    Lou, Z; Wang, H; Tang, Y; Chen, X

    2017-03-01

    This study aimed to evaluate the effect of a fraction of burdock (Arctium lappa L.) leaf on the initial adhesion, biofilm formation, quorum sensing and virulence factors of Pseudomonas aeruginosa. Antibiofilm activity of the burdock leaf fraction was studied by the method of crystal violet staining. When the concentration of the burdock leaf fraction was 2·0 mg ml -1 , the inhibition rates on biofilm formation of P. aeruginosa were 100%. The burdock leaf fraction was found to inhibit the formation of biofilm by reducing bacterial surface hydrophobicity, decreasing bacterial aggregation ability and inhibiting swarming motility. Interestingly, the burdock leaf fraction inhibited the secretion of quorum-sensing (QS) signalling molecule 3-oxo-C12-HSL and interfered quorum sensing. Moreover, the QS-regulated pyocyanin and elastase were also inhibited. Chemical composition analysis by UPLC-MS showed 11 active compounds in the burdock leaf fraction. The burdock leaf fraction significantly inhibited the formation of biofilm and quorum sensing, as well as significantly decreased the content of virulence factors. This study introduces a natural and effective bacterial biofilm inhibitor, which could also significantly decrease the content of virulence factors and the drug resistance of P. aeruginosa. © 2016 The Society for Applied Microbiology.

  20. Antipathogenic potential of Rhizophora spp. against the quorum sensing mediated virulence factors production in drug resistant Pseudomonas aeruginosa.

    Science.gov (United States)

    Annapoorani, Angusamy; Kalpana, Balaji; Musthafa, Khadar Syed; Pandian, Shunmugiah Karutha; Ravi, Arumugam Veera

    2013-08-15

    Quorum sensing (QS) is a process of cell-cell communication mechanism occurs between the bacterial cells through the secretary signal molecules. This QS mechanism has been shown to control over the expression of various genes responsible for the production of virulence factors in several bacterial pathogens. Hence, the present study was intended to evaluate the antipathogenic potential of mangrove trees of the genus Rhizophora against the QS dependent virulence factors production in Pseudomonas aeruginosa PAO1, clinical isolates CI-I (GU447237) and CI-II (GU447238). The methanol extract of Rhizophora apiculata and R. mucronata (1 mg/ml) showed significant inhibition against QS dependent virulence factors production such as LasA protease, LasB elastase, total protease, pyocyanin pigment production and biofilm formation in P. aeruginosa PAO1, CI-I and CI-II. This study for the first time, reports the quorum sensing inhibitory (QSI) potential of Rhizophora spp. against P. aeruginosa infections. Copyright © 2013 Elsevier GmbH. All rights reserved.

  1. Talaromyces marneffei Genomic, Transcriptomic, Proteomic and Metabolomic Studies Reveal Mechanisms for Environmental Adaptations and Virulence

    Directory of Open Access Journals (Sweden)

    Susanna K. P. Lau

    2017-06-01

    Full Text Available Talaromyces marneffei is a thermally dimorphic fungus causing systemic infections in patients positive for HIV or other immunocompromised statuses. Analysis of its ~28.9 Mb draft genome and additional transcriptomic, proteomic and metabolomic studies revealed mechanisms for environmental adaptations and virulence. Meiotic genes and genes for pheromone receptors, enzymes which process pheromones, and proteins involved in pheromone response pathway are present, indicating its possibility as a heterothallic fungus. Among the 14 Mp1p homologs, only Mp1p is a virulence factor binding a variety of host proteins, fatty acids and lipids. There are 23 polyketide synthase genes, one for melanin and two for mitorubrinic acid/mitorubrinol biosynthesis, which are virulence factors. Another polyketide synthase is for biogenesis of the diffusible red pigment, which consists of amino acid conjugates of monascorubin and rubropunctatin. Novel microRNA-like RNAs (milRNAs and processing proteins are present. The dicer protein, dcl-2, is required for biogenesis of two milRNAs, PM-milR-M1 and PM-milR-M2, which are more highly expressed in hyphal cells. Comparative transcriptomics showed that tandem repeat-containing genes were overexpressed in yeast phase, generating protein polymorphism among cells, evading host’s immunity. Comparative proteomics between yeast and hyphal cells revealed that glyceraldehyde-3-phosphate dehydrogenase, up-regulated in hyphal cells, is an adhesion factor for conidial attachment.

  2. In silico assessment of virulence factors in strains of Streptococcus oralis and Streptococcus mitis isolated from patients with Infective Endocarditis.

    Science.gov (United States)

    Rasmussen, Louise H; Højholt, Katrine; Dargis, Rimtas; Christensen, Jens Jørgen; Skovgaard, Ole; Justesen, Ulrik S; Rosenvinge, Flemming S; Moser, Claus; Lukjancenko, Oksana; Rasmussen, Simon; Nielsen, Xiaohui C

    2017-09-06

    Streptococcus oralis and Streptococcus mitis belong to the Mitis group, which are mostly commensals in the human oral cavity. Even though S. oralis and S. mitis are oral commensals, they can be opportunistic pathogens causing infective endocarditis. A recent taxonomic re-evaluation of the Mitis group has embedded the species Streptococcus tigurinus and Streptococcus dentisani into the species S. oralis as subspecies. In this study, the distribution of virulence factors that contribute to bacterial immune evasion, colonization and adhesion was assessed in clinical strains of S. oralis (subsp. oralis, subsp. tigurinus and subsp. dentisani) and S. mitis. Forty clinical S. oralis (subsp. oralis, subsp. dentisani and subsp. tigurinus) and S. mitis genomes were annotated with the pipeline PanFunPro and aligned against the VFDB database for assessment of virulence factors.Results/Key findings. Three homologues of pavA, psaA and lmb, encoding adhesion proteins, were present in all strains. Seven homologues of nanA, nanB, ply, lytA, lytB, lytC and iga, of importance regarding survival in blood and modulation of the human immune system, were variously present in the genomes. Few S. oralis subspecies specific differences were observed. iga homologues were identified in S. oralis subsp. oralis, whereas lytA homologues were identified in S. oralis subsp. oralis and subsp. tigurinus. Differences in the presence of virulence factors among the three S. oralis subspecies were observed. The virulence gene profiles of the 40 S. mitis and S. oralis (subsp. oralis, subsp. dentisani and subsp. tigurinus) contribute with important new knowledge regarding these species and new subspecies.

  3. Interdependence of environmental factors influencing reciprocal patterns of gene expression in virulent Borrelia burgdorferi.

    Science.gov (United States)

    Yang, X; Goldberg, M S; Popova, T G; Schoeler, G B; Wikel, S K; Hagman, K E; Norgard, M V

    2000-09-01

    The paradigm for differential antigen expression in Borrelia burgdorferi, the agent of Lyme disease, is the reciprocal expression of its outer surface (lipo)proteins (Osp) A and C; as B. burgdorferi transitions from its arthropod vector into mammalian tissue, ospC is upregulated, and ospA is downregulated. In the current study, using B. burgdorferi cultivated under varying conditions in BSK-H medium, we found that a decrease in pH, in conjunction with increases in temperature (e.g. 34 degrees C or 37 degrees C) and cell density, acted interdependently for the reciprocal expression of ospC and ospA. The lower pH (6.8), which induced the reciprocal expression of ospC and ospA in BSK-H medium, correlated with a drop in pH from 7.4 to 6.8 of tick midgut contents during tick feeding. In addition to ospC and ospA, other genes were found to be regulated in reciprocal fashion. Such genes were either ospC-like (e.g. ospF, mlp-8 and rpoS) (group I) or ospA-like (lp6.6 and p22) (group II); changes in expression occurred at the mRNA level. That the expression of rpoS, encoding a putative stress-related alternative sigma factor (sigma(s)), was ospC-like suggested that the expression of some of the group I genes may be controlled through sigma(s). The combined results prompt a model that allows for predicting the regulation of other B. burgdorferi genes that may be involved in spirochaete transmission, virulence or mammalian host immune responses.

  4. Phylogenetic relationships, virulence factors and Rep-PCR epidemiological analysis of E. coli from human sources

    Directory of Open Access Journals (Sweden)

    Simona Caroppo

    2010-06-01

    Full Text Available The potential of Escherichia coli to cause of extra-intestinal infections was studied on a group of 94 clinical isolates. In this work, 32 E. coli isolates from urinary tract infections, 25 from bacteraemia, 12 from low respiratory tract infections, and 25 from the normal commensal flora were characterized for the phylogenetic type, the virulence factors (VFs carriage and the Rep-PCR clonal composition.The B2 phylogenetic type was predominant among the urinary isolates (59%, the B2 and D strains among the haematic isolates (32% and 32%.The A phylogenetic type was predominant among the commensal and the respiratory isolates (52% and 58% respectively.The distribution of the B2 type strains among the urinary isolates and of the D type strains among the faecal isolates was suggesting a urinary-origin for the B2 phylogenetic type isolates found in the blood and a direct faecal derivation for the haematic isolates with D phylogenetic type.Twenty-nine VFs were analyzed.The B2 and D type strains carried a higher burden of VFs than the A and B1 phylogenetic type strains (average of VFs/strain = 8 vs 3. Some of the VFs were homogeneously distributed among the phylogenetic types (fimH, iutA, fyuA, traT. The PAI, papGII, ibeA, KpsMTIII were exclusive of B2 and D phylogenetic type strains, while sfa/foc, focG, cnf1, hlyA and rfc were exclusively observed among the B2 type strains.The clustering analysis by Rep-PCR distinguished two groups of strains, the first including 96.77% of B2 and D type strains, while the second encompassing 91,5% of A and B1 type strains.

  5. Determining the presence of periodontopathic virulence factors in short-term postmortem Alzheimer's disease brain tissue.

    Science.gov (United States)

    Poole, Sophie; Singhrao, Sim K; Kesavalu, Lakshmyya; Curtis, Michael A; Crean, StJohn

    2013-01-01

    The aim of this study was to establish a link between periodontal disease and Alzheimer's disease (AD) with a view to identifying the major periodontal disease bacteria (Treponema denticola, Tannerella forsythia, and Porphyromonas gingivalis) and/or bacterial components in brain tissue from 12 h postmortem delay. Our request matched 10 AD cases for tissue from Brains for Dementia Research alongside 10 non-AD age-related controls with similar or greater postmortem interval. We exposed SVGp12, an astrocyte cell line, to culture supernatant containing lipopolysaccharide (LPS) from the putative periodontal bacteria P. gingivalis. The challenged SVGp12 cells and cryosections from AD and control brains were immunolabeled and immunoblotted using a battery of antibodies including the anti-P. gingivalis-specific monoclonal antibody. Immunofluorescence labeling demonstrated the SVGp12 cell line was able to adsorb LPS from culture supernatant on its surface membrane; similar labeling was observed in four out of 10 AD cases. Immunoblotting demonstrated bands corresponding to LPS from P. gingivalis in the SVGp12 cell lysate and in the same four AD brain specimens which were positive when screened by immunofluorescence. All controls remained negative throughout while the same four cases were consistently positive for P. gingivalis LPS (p = 0.029). This study confirms that LPS from periodontal bacteria can access the AD brain during life as labeling in the corresponding controls, with equivalent/longer postmortem interval, was absent. Demonstration of a known chronic oral-pathogen-related virulence factor reaching the human brains suggests an inflammatory role in the existing AD pathology.

  6. Reduction of virulence factor pyocyanin production in multidrug-resistant Pseudomonas aeruginosa.

    Science.gov (United States)

    Fuse, Katsuhiro; Fujimura, Shigeru; Kikuchi, Toshiaki; Gomi, Kazunori; Iida, Yasuhiro; Nukiwa, Toshihiro; Watanabe, Akira

    2013-02-01

    Nosocomial infections caused by metallo-β-lactamase (MBL)-producing multidrug-resistant (MDR) Pseudomonas aeruginosa have become a worldwide problem. Pyocyanin, a representative pigment produced by P. aeruginosa, is the major virulence factor of this organismThe aim of this study was to investigate the pyocyanin-producing ability of MBL-producing MDR P. aeruginosa. A total of 50 clinical isolates of P. aeruginosa, including 20 MDR strains, were collected at 18 general hospitals in Japan. The chromaticity and luminosity produced by pyocyanin in each isolate were measured. The quantity of pyocyanin and the expression of the phzM and phzS genes coding a pyocyanin synthesis enzyme were measured. MDR strains showed a bright yellow-green, while non-MDR strains tended to show a dark blue-green. The quantities of pyocyanin in MBL-producing strains and non-producing strains were 0.015 ± 0.002 and 0.41 ± 0.10 μg, respectively. The expression of the phzM and phzS genes in the MDR strains was 11 and 14 %, respectively, of the expression in the non-MDR strains. When the MBL gene was transduced into P. aeruginosa and it acquired multidrug resistance, it was shown that the pyocyanin-producing ability decreased. The pathogenicity of MBL-producing MDR P. aeruginosa may be lower than that of non-MDR strains. These MBL-producing MDR strains may be less pathogenic than non-MDR strains. This may explain why MDR-P. aeruginosa is unlikely to cause infection but, rather, causes subclinical colonization only.

  7. ANTIBIOTICS RESISTANCE AND PUTATIVE VIRULENCE FACTORS OF AEROMONAS HYDROPHILA ISOLATED FROM ESTUARY

    Directory of Open Access Journals (Sweden)

    Olumide Adedokun Odeyemi

    2012-06-01

    Full Text Available This study aim to investigate antibiotics resistance profile and putative virulence factors of Aeromonas hydrophila isolated from estuary. Bacteria used for this study were isolated from water and sediment samples obtained from Sungai Melayu, Johor, Malaysia. Serially diluted 100 µL water and 1g sediment were inoculated on modified Rimler - Shott (mRS agar. Colonies with distinct cultural characteristics were picked for further studies. Isolates were tested for biofilm productions, protease enzyme and antibiotics resistance profile using agar well diffusion method against 10 commercial antibiotics. Congo Red Agar (CRA, Microplate and Standard Tube (ST methods were used for assessment of biofilm formation among the isolates while Skim Milk Agar was used for protease production. Sw.KMJ 3 and Sw.KMJ 9 produced black crystalline colonies on CRA. Six of the isolates were biofilm producers in ST method. Result of Microplate method, helped in grouping the isolates into weak (n = 8, moderate (n = 3 and strong producers (n = 4 at 540 nm wavelength. All the isolates were classified as weak ODc  ODi 0.1, moderate ODi = 0.1  0.12 and strong producers ODi  0.12 respectively at 540 nm wavelength. Antibiotics susceptibility test also revealed that all the isolates were resistant to between 6 and 10 antibiotics. Two isolates each were resistant to 6 (60 %, 7 (70 % and 9 (90 % antibiotics respectively. Eight of the isolates showed resistance to 8 (80 % antibiotics while only isolate Sw.KMJ-7 showed resistance to all the tested antibiotics. Sw.KMJ-3, Sw.KMJ-8 and Sw.KMJ-9 produced protease enzyme on SMA. The isolates were also found to be resistant to both antibiotics and heavy metals.

  8. Identification of Burkholderia cenocepacia strain H111 virulence factors using nonmammalian infection hosts

    DEFF Research Database (Denmark)

    Schwager, Stephan; Agnoli, Kirsty; Köthe, Manuela

    2013-01-01

    or siderophores. Instead, the mutants contained insertions in metabolic and regulatory genes. Mutants attenuated in virulence in the C. elegans infection model were also tested in the Drosophila melanogaster pricking model, and those also attenuated in this model were further tested in Galleria mellonella. Six...... of the 22 mutants were attenuated in D. melanogaster, and five of these were less pathogenic in the G. mellonella model. We show that genes encoding enzymes of the purine, pyrimidine, and shikimate biosynthesis pathways are critical for virulence in multiple host models of infection....

  9. Streptococcal collagen-like protein A and general stress protein 24 are immunomodulating virulence factors of group A Streptococcus.

    Science.gov (United States)

    Tsatsaronis, James A; Hollands, Andrew; Cole, Jason N; Maamary, Peter G; Gillen, Christine M; Ben Zakour, Nouri L; Kotb, Malak; Nizet, Victor; Beatson, Scott A; Walker, Mark J; Sanderson-Smith, Martina L

    2013-07-01

    In Western countries, invasive infections caused by M1T1 serotype group A Streptococcus (GAS) are epidemiologically linked to mutations in the control of virulence regulatory 2-component operon (covRS). In indigenous communities and developing countries, severe GAS disease is associated with genetically diverse non-M1T1 GAS serotypes. Hypervirulent M1T1 covRS mutant strains arise through selection by human polymorphonuclear cells for increased expression of GAS virulence factors such as the DNase Sda1, which promotes neutrophil resistance. The GAS bacteremia isolate NS88.2 (emm 98.1) is a covS mutant that exhibits a hypervirulent phenotype and neutrophil resistance yet lacks the phage-encoded Sda1. Here, we have employed a comprehensive systems biology (genomic, transcriptomic, and proteomic) approach to identify NS88.2 virulence determinants that enhance neutrophil resistance in the non-M1T1 GAS genetic background. Using this approach, we have identified streptococcal collagen-like protein A and general stress protein 24 proteins as NS88.2 determinants that contribute to survival in whole blood and neutrophil resistance in non-M1T1 GAS. This study has revealed new factors that contribute to GAS pathogenicity that may play important roles in resisting innate immune defenses and the development of human invasive infections.

  10. PoxA, yjeK, and elongation factor P coordinately modulate virulence and drug resistance in Salmonella enterica

    DEFF Research Database (Denmark)

    Navarre, William Wiley; Zou, S Betty; Roy, Hervé

    2010-01-01

    We report an interaction between poxA, encoding a paralog of lysyl tRNA-synthetase, and the closely linked yjeK gene, encoding a putative 2,3-beta-lysine aminomutase, that is critical for virulence and stress resistance in Salmonella enterica. Salmonella poxA and yjeK mutants share extensive...... phenotypic pleiotropy, including attenuated virulence in mice, an increased ability to respire under nutrient-limiting conditions, hypersusceptibility to a variety of diverse growth inhibitors, and altered expression of multiple proteins, including several encoded on the SPI-1 pathogenicity island. PoxA...... mediates posttranslational modification of bacterial elongation factor P (EF-P), analogous to the modification of the eukaryotic EF-P homolog, eIF5A, with hypusine. The modification of EF-P is a mechanism of regulation whereby PoxA acts as an aminoacyl-tRNA synthetase that attaches an amino acid...

  11. Putative virulence factors of the Aeromonas spp. isolated from food and environment in Abu Dhabi, United Arab Emirates.

    Science.gov (United States)

    Awan, Mohammad Bashir; Ahmed, M Maqbool; Bari, Abdul; Krovacek, Karel

    2006-07-01

    Thirty randomly selected Aeromonas isolates from food and the environment in Abu Dhabi, United Arab Emirates, were characterized for putative virulence determinants, such as production of cytotoxin, cytotonic toxin, and hemolysin and their capacity to adhere to and invade Henle 407 cells in vitro. Seventy percent of the tested isolates were cytotoxin producers, and 80% were hemolytic. Cytotoxin was produced by 6 of 7 A. hydrophila strains, 6 of 13 A. caviae strains, and 6 of 7 A. veronii bv. sobria strains, mostly from food sources. A. schubertii, A. jandaei, and A. trota also produced both cytotoxin and hemolysin. All of the 30 isolates tested adhered to Henle 407 cells, but none were able to invade the cells, as determined with the in vitro assay. However, no significant correlation of the presence of these putative virulence factors was found among these aeromonad food isolates.

  12. Unravelling the contribution of the Penicillium expansum PeSte12 transcription factor to virulence during apple fruit infection.

    Science.gov (United States)

    Sánchez-Torres, Paloma; Vilanova, Laura; Ballester, Ana Rosa; López-Pérez, Mario; Teixidó, Neus; Viñas, Inmaculada; Usall, Josep; González-Candelas, Luis; Torres, Rosario

    2018-02-01

    Blue mould disease caused by Penicillium expansum infection is one of the most important diseases of pome fruit accounting for important economic losses. In the present study, the PeSte12 transcription factor gene was identified, and deletant mutants were produced by gene replacement. Knockout mutants showed a significant decrease of virulence during apple fruit infection. Virulence was affected by the maturity stage of the fruit (immature, mature and over-mature), and disease severity was notably reduced when the apples were stored at 0 °C. The ΔPeSte12 mutants resulted defective in asexual reproduction, producing less conidia, but this characteristic did not correlate with differences in microscopic morphology. In addition, the ΔPeSte12 mutants produced higher quantity of hydrogen peroxide than the wild type strain. Gene expression analysis revealed that PeSte12 was induced over time during apple infection compared to axenic growth, particularly from 2 dpi, reinforcing its role in virulence. Analysis of transcriptional abundance of several genes in ΔPeSte12 mutants showed that in most of the evaluated genes, PeSte12 seemed to act as a negative regulator during axenic growth, as most of them exhibited an increasing expression pattern along the time period evaluated. The highest expression values corresponded to detoxification, ATPase activity, protein folding and basic metabolism. Gene expression analysis during apple infection showed that 3 out of 9 analysed genes were up regulated; thus, PeSte12 seemed to exert a positive control to particular type of aldolase. These results demonstrate the PeSte12 transcription factor could play an important role in P. expansum's virulence and asexual reproduction. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. The transcription factor BcLTF1 regulates virulence and light responses in the necrotrophic plant pathogen Botrytis cinerea.

    Directory of Open Access Journals (Sweden)

    Julia Schumacher

    2014-01-01

    Full Text Available Botrytis cinerea is the causal agent of gray mold diseases in a range of dicotyledonous plant species. The fungus can reproduce asexually by forming macroconidia for dispersal and sclerotia for survival; the latter also participate in sexual reproduction by bearing the apothecia after fertilization by microconidia. Light induces the differentiation of conidia and apothecia, while sclerotia are exclusively formed in the absence of light. The relevance of light for virulence of the fungus is not obvious, but infections are observed under natural illumination as well as in constant darkness. By a random mutagenesis approach, we identified a novel virulence-related gene encoding a GATA transcription factor (BcLTF1 for light-responsive TF1 with characterized homologues in Aspergillus nidulans (NsdD and Neurospora crassa (SUB-1. By deletion and over-expression of bcltf1, we confirmed the predicted role of the transcription factor in virulence, and discovered furthermore its functions in regulation of light-dependent differentiation, the equilibrium between production and scavenging of reactive oxygen species (ROS, and secondary metabolism. Microarray analyses revealed 293 light-responsive genes, and that the expression levels of the majority of these genes (66% are modulated by BcLTF1. In addition, the deletion of bcltf1 affects the expression of 1,539 genes irrespective of the light conditions, including the overexpression of known and so far uncharacterized secondary metabolism-related genes. Increased expression of genes encoding alternative respiration enzymes, such as the alternative oxidase (AOX, suggest a mitochondrial dysfunction in the absence of bcltf1. The hypersensitivity of Δbctlf1 mutants to exogenously applied oxidative stress--even in the absence of light--and the restoration of virulence and growth rates in continuous light by antioxidants, indicate that BcLTF1 is required to cope with oxidative stress that is caused either by

  14. The Transcription Factor BcLTF1 Regulates Virulence and Light Responses in the Necrotrophic Plant Pathogen Botrytis cinerea

    Science.gov (United States)

    Schumacher, Julia; Simon, Adeline; Cohrs, Kim Christopher; Viaud, Muriel; Tudzynski, Paul

    2014-01-01

    Botrytis cinerea is the causal agent of gray mold diseases in a range of dicotyledonous plant species. The fungus can reproduce asexually by forming macroconidia for dispersal and sclerotia for survival; the latter also participate in sexual reproduction by bearing the apothecia after fertilization by microconidia. Light induces the differentiation of conidia and apothecia, while sclerotia are exclusively formed in the absence of light. The relevance of light for virulence of the fungus is not obvious, but infections are observed under natural illumination as well as in constant darkness. By a random mutagenesis approach, we identified a novel virulence-related gene encoding a GATA transcription factor (BcLTF1 for light-responsive TF1) with characterized homologues in Aspergillus nidulans (NsdD) and Neurospora crassa (SUB-1). By deletion and over-expression of bcltf1, we confirmed the predicted role of the transcription factor in virulence, and discovered furthermore its functions in regulation of light-dependent differentiation, the equilibrium between production and scavenging of reactive oxygen species (ROS), and secondary metabolism. Microarray analyses revealed 293 light-responsive genes, and that the expression levels of the majority of these genes (66%) are modulated by BcLTF1. In addition, the deletion of bcltf1 affects the expression of 1,539 genes irrespective of the light conditions, including the overexpression of known and so far uncharacterized secondary metabolism-related genes. Increased expression of genes encoding alternative respiration enzymes, such as the alternative oxidase (AOX), suggest a mitochondrial dysfunction in the absence of bcltf1. The hypersensitivity of Δbctlf1 mutants to exogenously applied oxidative stress - even in the absence of light - and the restoration of virulence and growth rates in continuous light by antioxidants, indicate that BcLTF1 is required to cope with oxidative stress that is caused either by exposure to light

  15. Genotypes, Virulence Factors and Antimicrobial Resistance Genes of Staphylococcus aureus Isolated in Bovine Subclinical Mastitis from Eastern China

    Directory of Open Access Journals (Sweden)

    Javed Memon§, Yongchun Yang§, Jam Kashifa, Muhammad Yaqoob, Rehana Buriroa, Jamila Soomroa, Wang Liping and Fan Hongjie*

    2013-11-01

    Full Text Available This study was carried out to determine the genotypes, virulence factors and antimicrobial resistance traits of 34 Staphylococcus aureus isolated from subclinical mastitis in Eastern China. Minimal inhibitory concentration (MIC results showed resistance to erythromycin in all isolates. A high frequency of Methicillin resistant S. aureus (MRSA; 29% was observed and these isolates were also highly resistant to penicillin, oxacillin, oxytetracycline and chloramphenicol than methicillin sensitive S. aureus (MSSA isolates. Thirteen pathogenic factors and seven resistance genes including mecA and blaZ gene were checked through PCR. The spaX gene was found in all isolates, whereas cna, spaIg, nuc, clfA, fnbpB, hlA, hlB and seA were present in 35, 79, 85, 59, 35, 85, 71 and 38% isolates, respectively. Nine isolates carried a group of 8 different virulence genes. Moreover, macrolide resistance genes ermB and ermC were present in all isolates. High resistance rate against methicillin was found but no isolate was positive for mecA gene, whereas blaZ and tetK were detected in 82 and 56% isolates, respectively. Genes; fnbpA, seB, seC, seD, dfrK and tetM were not found in any isolate. The statistical association between phenotypic resistance and virulence genes showed, clfA, fnbpB, hlB and seA, were potentially associated with penicillin G, ciprofloxacin, methicillin, chloramphenicol, trimethoprim and oxytetracycline resistance (P≤0.05. REP-PCR based genotyping showed seven distinct genotypes (A-G prevalent in this region. This study reports the presence of multidrug resistant S. aureus in sub-clinical mastitis which were also highly virulent that could be a major obstacle in the treatment of mastitis in this region of China.

  16. Listeriolysin S Is a Streptolysin S-Like Virulence Factor That Targets Exclusively Prokaryotic Cells In Vivo

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    Juan J. Quereda

    2017-04-01

    Full Text Available Streptolysin S (SLS-like virulence factors from clinically relevant Gram-positive pathogens have been proposed to behave as potent cytotoxins, playing key roles in tissue infection. Listeriolysin S (LLS is an SLS-like hemolysin/bacteriocin present among Listeria monocytogenes strains responsible for human listeriosis outbreaks. As LLS cytotoxic activity has been associated with virulence, we investigated the LLS-specific contribution to host tissue infection. Surprisingly, we first show that LLS causes only weak red blood cell (RBC hemolysis in vitro and neither confers resistance to phagocytic killing nor favors survival of L. monocytogenes within the blood cells or in the extracellular space (in the plasma. We reveal that LLS does not elicit specific immune responses, is not cytotoxic for eukaryotic cells, and does not impact cell infection by L. monocytogenes. Using in vitro cell infection systems and a murine intravenous infection model, we actually demonstrate that LLS expression is undetectable during infection of cells and murine inner organs. Importantly, upon intravenous animal inoculation, L. monocytogenes is found in the gastrointestinal system, and only in this environment LLS expression is detected in vivo. Finally, we confirm that LLS production is associated with destruction of target bacteria. Our results demonstrate therefore that LLS does not contribute to L. monocytogenes tissue injury and virulence in inner host organs as previously reported. Moreover, we describe that LlsB, a putative posttranslational modification enzyme encoded in the LLS operon, is necessary for murine inner organ colonization. Overall, we demonstrate that LLS is the first SLS-like virulence factor targeting exclusively prokaryotic cells during in vivo infections.

  17. Elongation factor P mediates a novel post-transcriptional regulatory pathway critical for bacterial virulence

    DEFF Research Database (Denmark)

    Zou, S Betty; Roy, Hervé; Ibba, Michael

    2012-01-01

    of the pathogen to respond to external cues are typically attenuating. Here we discuss our recent discovery of a novel post-transcriptional regulatory pathway critical for Salmonella virulence and stress resistance. The enzymes PoxA and YjeK coordinately attach a unique beta-amino acid onto a highly conserved...

  18. Reconstruction of the metabolic network of Pseudomonas aeruginosa to interrogate virulence factor synthesis

    DEFF Research Database (Denmark)

    Bartell, Jennifer; Blazier, Anna S; Yen, Phillip

    2017-01-01

    to metabolism. We evaluate the complex interrelationships between growth and virulence-linked pathways using a genome-scale metabolic network reconstruction of Pseudomonas aeruginosa strain PA14 and an updated, expanded reconstruction of P. aeruginosa strain PAO1. The PA14 reconstruction accounts...

  19. The role of virulence factors in the outcome of staphylococcal peritonitis in CAPD patients

    Directory of Open Access Journals (Sweden)

    Caramori Jacqueline CT

    2009-12-01

    = 0.04 production were independent predictors of non-resolution. Conclusion Bacterial species and virulence factors rather than antibiotic resistance influence the outcome of staphylococcal peritonitis.

  20. The role of the multiple banded antigen of Ureaplasma parvum in intra-amniotic infection: major virulence factor or decoy?

    Directory of Open Access Journals (Sweden)

    Samantha J Dando

    Full Text Available The multiple banded antigen (MBA is a predicted virulence factor of Ureaplasma species. Antigenic variation of the MBA is a potential mechanism by which ureaplasmas avoid immune recognition and cause chronic infections of the upper genital tract of pregnant women. We tested whether the MBA is involved in the pathogenesis of intra-amniotic infection and chorioamnionitis by injecting virulent or avirulent-derived ureaplasma clones (expressing single MBA variants into the amniotic fluid of pregnant sheep. At 55 days of gestation pregnant ewes (n = 20 received intra-amniotic injections of virulent-derived or avirulent-derived U. parvum serovar 6 strains (2×10⁴ CFU, or 10B medium (n = 5. Amniotic fluid was collected every two weeks post-infection and fetal tissues were collected at the time of surgical delivery of the fetus (140 days of gestation. Whilst chronic colonisation was established in the amniotic fluid of animals infected with avirulent-derived and virulent-derived ureaplasmas, the severity of chorioamnionitis and fetal inflammation was not different between these groups (p>0.05. MBA size variants (32-170 kDa were generated in vivo in amniotic fluid samples from both the avirulent and virulent groups, whereas in vitro antibody selection experiments led to the emergence of MBA-negative escape variants in both strains. Anti-ureaplasma IgG antibodies were detected in the maternal serum of animals from the avirulent (40% and virulent (55% groups, and these antibodies correlated with increased IL-1β, IL-6 and IL-8 expression in chorioamnion tissue (p<0.05. We demonstrate that ureaplasmas are capable of MBA phase variation in vitro; however, ureaplasmas undergo MBA size variation in vivo, to potentially prevent eradication by the immune response. Size variation of the MBA did not correlate with the severity of chorioamnionitis. Nonetheless, the correlation between a maternal humoral response and the expression of chorioamnion

  1. The Role of the Multiple Banded Antigen of Ureaplasma parvum in Intra-Amniotic Infection: Major Virulence Factor or Decoy?

    Science.gov (United States)

    Dando, Samantha J.; Nitsos, Ilias; Kallapur, Suhas G.; Newnham, John P.; Polglase, Graeme R.; Pillow, J. Jane; Jobe, Alan H.; Timms, Peter; Knox, Christine L.

    2012-01-01

    The multiple banded antigen (MBA) is a predicted virulence factor of Ureaplasma species. Antigenic variation of the MBA is a potential mechanism by which ureaplasmas avoid immune recognition and cause chronic infections of the upper genital tract of pregnant women. We tested whether the MBA is involved in the pathogenesis of intra-amniotic infection and chorioamnionitis by injecting virulent or avirulent-derived ureaplasma clones (expressing single MBA variants) into the amniotic fluid of pregnant sheep. At 55 days of gestation pregnant ewes (n = 20) received intra-amniotic injections of virulent-derived or avirulent-derived U. parvum serovar 6 strains (2×104 CFU), or 10B medium (n = 5). Amniotic fluid was collected every two weeks post-infection and fetal tissues were collected at the time of surgical delivery of the fetus (140 days of gestation). Whilst chronic colonisation was established in the amniotic fluid of animals infected with avirulent-derived and virulent-derived ureaplasmas, the severity of chorioamnionitis and fetal inflammation was not different between these groups (p>0.05). MBA size variants (32–170 kDa) were generated in vivo in amniotic fluid samples from both the avirulent and virulent groups, whereas in vitro antibody selection experiments led to the emergence of MBA-negative escape variants in both strains. Anti-ureaplasma IgG antibodies were detected in the maternal serum of animals from the avirulent (40%) and virulent (55%) groups, and these antibodies correlated with increased IL-1β, IL-6 and IL-8 expression in chorioamnion tissue (p<0.05). We demonstrate that ureaplasmas are capable of MBA phase variation in vitro; however, ureaplasmas undergo MBA size variation in vivo, to potentially prevent eradication by the immune response. Size variation of the MBA did not correlate with the severity of chorioamnionitis. Nonetheless, the correlation between a maternal humoral response and the expression of chorioamnion cytokines is a

  2. The role of the multiple banded antigen of Ureaplasma parvum in intra-amniotic infection: major virulence factor or decoy?

    Science.gov (United States)

    Dando, Samantha J; Nitsos, Ilias; Kallapur, Suhas G; Newnham, John P; Polglase, Graeme R; Pillow, J Jane; Jobe, Alan H; Timms, Peter; Knox, Christine L

    2012-01-01

    The multiple banded antigen (MBA) is a predicted virulence factor of Ureaplasma species. Antigenic variation of the MBA is a potential mechanism by which ureaplasmas avoid immune recognition and cause chronic infections of the upper genital tract of pregnant women. We tested whether the MBA is involved in the pathogenesis of intra-amniotic infection and chorioamnionitis by injecting virulent or avirulent-derived ureaplasma clones (expressing single MBA variants) into the amniotic fluid of pregnant sheep. At 55 days of gestation pregnant ewes (n = 20) received intra-amniotic injections of virulent-derived or avirulent-derived U. parvum serovar 6 strains (2×10⁴ CFU), or 10B medium (n = 5). Amniotic fluid was collected every two weeks post-infection and fetal tissues were collected at the time of surgical delivery of the fetus (140 days of gestation). Whilst chronic colonisation was established in the amniotic fluid of animals infected with avirulent-derived and virulent-derived ureaplasmas, the severity of chorioamnionitis and fetal inflammation was not different between these groups (p>0.05). MBA size variants (32-170 kDa) were generated in vivo in amniotic fluid samples from both the avirulent and virulent groups, whereas in vitro antibody selection experiments led to the emergence of MBA-negative escape variants in both strains. Anti-ureaplasma IgG antibodies were detected in the maternal serum of animals from the avirulent (40%) and virulent (55%) groups, and these antibodies correlated with increased IL-1β, IL-6 and IL-8 expression in chorioamnion tissue (p<0.05). We demonstrate that ureaplasmas are capable of MBA phase variation in vitro; however, ureaplasmas undergo MBA size variation in vivo, to potentially prevent eradication by the immune response. Size variation of the MBA did not correlate with the severity of chorioamnionitis. Nonetheless, the correlation between a maternal humoral response and the expression of chorioamnion cytokines is a

  3. Multiple virulence factors regulated by quorum sensing may help in establishment and colonisation of urinary tract by Pseudomonas aeruginosa during experimental urinary tract infection

    Directory of Open Access Journals (Sweden)

    P Gupta

    2013-01-01

    Full Text Available Purpose: Damage caused by an organism during infection is attributed to production of virulence factors. Different virulence factors produced by the organism contribute to its pathogenicity, individually. During infectious conditions, role of virulence factors produced by the pathogen is different, depending upon the site of involvement. Pseudomonas aeruginosa is an opportunistic nosocomial pathogen known to cause infections of the respiratory tract, burn wound, urinary tract and eye. Importance of virulence factors produced by P. Aeruginosa during infections such as keratitis, burn wound and respiratory tract is known. The present study was designed to understand the importance of different virulence factors of P. aeruginosa in urinary tract infection in vivo. Materials and methods: An ascending urinary tract infection model was established in mice using standard parent strain PAO1 and its isogenic mutant, JP2. Mice were sacrificed at different time intervals and renal tissue homogenates were used for estimation of renal bacterial load and virulence factors. Results: Both parent and mutant strains were able to reach the renal tissue. PAO 1 PAO1was isolated from renal tissue till day 5 post-infection. However, the mutant strain was unable to colonise the renal tissue. Failure of mutant strain to colonise was attributed to its inability to produce protease, elastase and rhamnolipid. Conclusion: This study suggests that protease, elastase and rhamnolipid contribute to pathogenesis and survival of P. aeruginosa during urinary tract infection.

  4. Staphylococcus aureus hijacks a skin commensal to intensify its virulence: immunization targeting β-hemolysin and CAMP factor.

    Science.gov (United States)

    Lo, Chih-Wei; Lai, Yiu-Kay; Liu, Yu-Tsueng; Gallo, Richard L; Huang, Chun-Ming

    2011-02-01

    The need for a new anti-Staphylococcus aureus therapy that can effectively cripple bacterial infection, neutralize secretory virulence factors, and lower the risk of creating bacterial resistance is undisputed. Here, we propose what is, to our knowledge, a previously unreported infectious mechanism by which S. aureus may commandeer Propionibacterium acnes, a key member of the human skin microbiome, to spread its invasion and highlight two secretory virulence factors (S. aureus β-hemolysin and P. acnes CAMP (Christie, Atkins, Munch-Peterson) factor) as potential molecular targets for immunotherapy against S. aureus infection. Our data demonstrate that the hemolysis and cytolysis by S. aureus were noticeably augmented when S. aureus was grown with P. acnes. The augmentation was significantly abrogated when the P. acnes CAMP factor was neutralized or β-hemolysin of S. aureus was mutated. In addition, the hemolysis and cytolysis of recombinant β-hemolysin were markedly enhanced by recombinant CAMP factor. Furthermore, P. acnes exacerbated S. aureus-induced skin lesions in vivo. The combination of CAMP factor neutralization and β-hemolysin immunization cooperatively suppressed the skin lesions caused by coinfection of P. acnes and S. aureus. These observations suggest a previously unreported immunotherapy targeting the interaction of S. aureus with a skin commensal.

  5. Aquatic microbiota diversity in the culture of Nile tilapia (Oreochromis niloticus using bioflocs or periphyton: virulence factors and biofilm formation

    Directory of Open Access Journals (Sweden)

    Jéssica Lucinda Saldanha da Silva

    2016-08-01

    Full Text Available The following research isolated and identified the main bacterial groups present in the culture of juvenile Nile tilapia in the presence of bioflocs and/or periphyton. The strains were also tested for the production of exoenzymes, indicative of potential virulence factors, and ability to form biofilm. The water samples were taken from tilapia cultured in the presence of bioflocs (T1, in the presence of bioflocs and periphyton (T2, from traditional culture (T3 and from culture in the presence of periphyton (T4. In the growth and selection of the bacterial groups, pour plate method was used, along with the following media: Plate Count Agar (PCA - DIFCO, Aero Pseudo Selective Agar (GSP - Himedia and Nutrient Agar (AN - Merck. 46 strains were isolated in the following distribution: T1 (n = 12; T2 (n = 10; T3 (n = 14 and T4 (n = 10. Among the isolates, the most frequent genera were: Pseudomonas spp., Aeromonas spp., Staphylococcus spp., Bacillus spp., Mycobacterium spp., Micrococcus spp., and Corybacterium spp. Bacterial isolates in treatments T1 and T3 tested positive for five virulence profiles each, while those isolated from T2 and T4 for two and three virulence profiles, respectively. Treatments in bioflocs and periphyton (T2 or only periphyton (T4 yielded bacteria of less pathogenic potentials. In relation to the fish growth, T1 and T4 resulted in a higher final weight.

  6. Antibiotic resistance genes and virulence factors in Enterococcus faecium and Enterococcus faecalis from diseased farm animals: pigs, cattle and poultry.

    Science.gov (United States)

    Seputiene, V; Bogdaite, A; Ruzauskas, M; Suziedeliene, E

    2012-01-01

    Eighty enterococcal isolates (E. faecium, n = 38, E. faecalis, n = 42) from diseased farm animals (swine, cattle, poultry) in Lithuania have been studied for the prevalence of antibiotic resistance and for resistance and virulence genetic determinants. 86% of E. faecium and 71% of E. faecalis isolates were multidrug resistant (resistant to three or more unrelated antibiotics). Resistance to aminoglycosides, tetracycline and erythromycin was found most frequently in both species (61%, 69%) and was linked to aph(3')-IIIa, aac(6')-Ie-aph(2")-Ia, ant(6)-Ia (aminoglycoside resistance), tetM, tetL (tetracycline resistance), ermA, ermB (erythromycin resistance) gene combinations, which were supplemented with chloramphenicol resistance genes catA7, catA8 (E. faecalis) and catA9 (E. faecium). All E. faecalis isolates harboured genes coding for virulence factors agg, esp, fsr gelE alone or in combinations with the high prevalence of esp gene in isolates from cattle (63%) and pigs (79%). The origin-dependent incidence of agg gene variants prgB and asp1 was observed. The results indicate the existence of a large pool of potentially virulent and multidrug resistant E. faecalis in diseased farm animals posing risk to humans.

  7. Relationship between Escherichia coli virulence factors and postpartum metritis in dairy cows.

    Science.gov (United States)

    Kassé, F N; Fairbrother, J M; Dubuc, J

    2016-06-01

    The objectives of this study were to report the prevalence of Escherichia coli and Trueperella pyogenes in the uterus of postpartum dairy cows before the onset of postpartum metritis (PPM) and to quantify their association with subsequent occurrence of PPM, to quantify the association between the presence of genes encoding E. coli virulence factors (VF) and PPM, and to determine the accuracy of using early postpartum uterine bacteriology results (bacteria and VF) to identify cows at risk of PPM. A prospective cohort study was conducted on 3 commercial dairy farms. Uterine swabs were collected from 371 Holstein dairy cows (3 commercial herds) at 1 to 7d in milk and submitted to the laboratory for identification of E. coli, T. pyogenes, and E. coli VF. A total of 40 VF were tested using the radioactive probe hybridization method. Postpartum metritis was defined as the presence of a fetid watery red-brown uterine discharge, associated with fever (rectal temperature >39.5°C), and systemic signs of illness (dullness, reduced appetite, and milk production). Surveillance of PPM was done by trained farmers blinded to laboratory results and cows were followed until 21d in milk. Statistical analyses were conducted using 2×2 tables and mixed logistical regression models. Prevalences of E. coli, T. pyogenes, and PPM were 42, 34, and 15%, respectively. A total of 32 VF were found in E. coli isolates. Most prevalent VF were extraintestinal pathogenic genes such as fimH (89%), hlyE (87%), and iss (70%). Cows positive for intrauterine E. coli were 3.2 times more likely to have subsequent PPM compared with bacteriologically negative cows. Cows with VF hra1 in their uterus were 2.7 times more likely to have PPM than cows positive for E. coli and negative for hra1 and 5.9 times more likely than bacteriologically negative cows. Cows with VF kpsMTII in their uterus were 3.2 times more likely to have PPM than cows positive for E. coli and negative for kpsMTII and 6.2 times more likely

  8. Genomic Features of Environmental and Clinical Vibrio parahaemolyticus Isolates Lacking Recognized Virulence Factors Are Dissimilar

    Science.gov (United States)

    Petronella, N.; Chew Leung, C.; Pightling, A. W.; Banerjee, S. K.

    2015-01-01

    Vibrio parahaemolyticus is a bacterial pathogen that can cause illness after the consumption or handling of contaminated seafood. The primary virulence factors associated with V. parahaemolyticus illness are thermostable direct hemolysin (TDH) and Tdh-related hemolysin (TRH). However, clinical strains lacking tdh and trh have recently been isolated, and these clinical isolates are poorly understood. To help understand the emergence of clinical tdh- and trh-negative isolates, a genomic approach was used to comprehensively compare 4 clinical tdh- and trh-negative isolates with 16 environmental tdh- and trh-negative isolates and 34 clinical isolates positive for tdh or trh, or both, with the objective of identifying genomic features that are unique to clinical tdh- and trh-negative isolates. The prevalence of pathogenicity islands (PAIs) common to clinical isolates was thoroughly examined in each of the clinical tdh- and trh-negative isolates. The tdh PAI was not present in any clinical or environmental tdh- and trh-negative isolates. The trh PAI was not present in any environmental isolates; however, in clinical tdh- and trh-negative isolate 10-4238, the majority of the trh PAI including a partial trh1 gene was present, which resulted in reclassification of this isolate as a tdh-negative and trh-positive isolate. In the other clinical tdh- and trh-negative isolates, neither the trh gene nor the trh PAI was present. We identified 862 genes in clinical tdh- and trh-negative isolates but not in environmental tdh- and trh-negative isolates. Many of these genes are highly homologous to genes found in common enteric bacteria and included genes encoding a number of chemotaxis proteins and a novel putative type VI secretion system (T6SS) effector and immunity protein (T6SS1). The availability of genome sequences from clinical V. parahaemolyticus tdh- and trh-negative isolates and the comparative analysis may help provide an understanding of how this pathotype is able to

  9. Assessment of virulence factors, antibiotic resistance and amino-decarboxylase activity in Enterococcus faecium MXVK29 isolated from Mexican chorizo.

    Science.gov (United States)

    Alvarez-Cisneros, Y M; Fernández, F J; Sainz-Espuñez, T; Ponce-Alquicira, E

    2017-02-01

    Enterococcus faecium MXVK29 has the ability to produce an antimicrobial compound that belongs to Class IIa of the Klaenhammer classification, and could be used as part of a biopreservation technology through direct inoculation of the strain as a starter or protective culture. However, Enterococcus is considered as an opportunistic pathogen, hence, the purpose of this work was to study the food safety determinants of E. faecium MXVK29. The strain was sensitive to all of the antibiotics tested (penicillin, tetracycline, vancomycin, erythromycin, chloramphenicol, gentamicin, neomycin, kanamycin and netilmicin) and did not demonstrate histamine, cadaverine or putrescine formation. Furthermore, tyrosine-decarboxylase activity was detected by qualitative assays and PCR. Among the virulence factors analysed for the strain, only the genes encoding the sexual pheromone cCF10 precursor lipoprotein (ccf) and cell-wall adhesion (efaA fm ) were amplified. The presence of these genes has low impact on pathogenesis, as there are no other genes encoding for virulence factors, such as aggregation proteins. Therefore, Enterococcus faecium could be employed as part of a bioconservation method, because it does not produce risk factors for consumer's health; in addition, it could be used as part of the hurdle technology in foods. The use of molecular techniques has allowed, in recent years, to detect pathogenicity genes present in the genome of starter cultures used in food processing and preservation. The presence of these genes is undesirable, because horizontal transfer may occur with the natural biota of consumers. For this reason, it is important to analyse the presence of pathogenicity genes in such cultures. In this work, virulence factors and antibiotic resistance of Enterococcus faecium strain MXVK29, producing an antimicrobial compound with high antilisterial activity, were analysed. The results indicate that the strain is safe to be used in food processing as starter

  10. Shiga toxin-producing Escherichia coli isolated from chicken meat in Iran: serogroups, virulence factors, and antimicrobial resistance properties.

    Science.gov (United States)

    Momtaz, Hassan; Jamshidi, Alireza

    2013-05-01

    The aim of the current study was to determine the virulence factors, serogroups, and antibiotic resistance properties of Shiga toxin-producing Escherichia coli isolated from chicken meat samples. A total of 422 chicken meat samples were collected from 5 townships of Iran. Specimens were immediately transferred to the laboratory in a cooler with an ice pack. Samples were cultured, and the positive culture samples were analyzed by PCR assays. Finally, the antimicrobial susceptibility test was performed using the disk diffusion method in Mueller-Hinton agar. According to the results, out of 422 samples, 146 (34.59%) were confirmed to be E. coli positive and among E. coli-positive samples, 51 (34.93%) and 31 (21.23%) were from attaching and effacing E. coli (AEEC) and enterohemorrhagic E. coli (EHEC) subgroups, respectively. All of the EHEC-positive samples had all stx1, eaeA, and ehly virulence genes, whereas only 5 (9.80%) of AEEC subgroup had all stx1, stx2, and eaeA genes. As the data revealed, O157 was the most prevalent and O111 was the least prevalent strains in the Shiga toxin-producing E. coli (STEC) population. Among STEC strains, sulI and blaSHV had the highest and lowest incidence rate, respectively. There was a high resistance to tetracycline (76.82%), followed by chloramphenicol (73.17%) and nitrofurantoin (63.41%), but there was low resistance to cephalotine (7.31%) antibiotics in isolated strains. Results shows that the PCR technique has a high performance for detection of serogroups, virulence genes, and antibiotic resistance genes in STEC strains. This study is the first prevalence report of detection of virulence genes, serogroups, and antibiotic resistance properties of STEC strains isolated from chicken meat samples in Iran. Based on the results, chicken meat is one of the main sources of STEC strains and its virulence factors in Iran, so an accurate meat inspection would reduce disease outbreaks.

  11. Listeriolysin S Is a Streptolysin S-Like Virulence Factor That Targets Exclusively Prokaryotic CellsIn Vivo.

    Science.gov (United States)

    Quereda, Juan J; Nahori, Marie A; Meza-Torres, Jazmín; Sachse, Martin; Titos-Jiménez, Patricia; Gomez-Laguna, Jaime; Dussurget, Olivier; Cossart, Pascale; Pizarro-Cerdá, Javier

    2017-04-04

    Streptolysin S (SLS)-like virulence factors from clinically relevant Gram-positive pathogens have been proposed to behave as potent cytotoxins, playing key roles in tissue infection. Listeriolysin S (LLS) is an SLS-like hemolysin/bacteriocin present among Listeria monocytogenes strains responsible for human listeriosis outbreaks. As LLS cytotoxic activity has been associated with virulence, we investigated the LLS-specific contribution to host tissue infection. Surprisingly, we first show that LLS causes only weak red blood cell (RBC) hemolysis in vitro and neither confers resistance to phagocytic killing nor favors survival of L. monocytogenes within the blood cells or in the extracellular space (in the plasma). We reveal that LLS does not elicit specific immune responses, is not cytotoxic for eukaryotic cells, and does not impact cell infection by L. monocytogenes Using in vitro cell infection systems and a murine intravenous infection model, we actually demonstrate that LLS expression is undetectable during infection of cells and murine inner organs. Importantly, upon intravenous animal inoculation, L. monocytogenes is found in the gastrointestinal system, and only in this environment LLS expression is detected in vivo Finally, we confirm that LLS production is associated with destruction of target bacteria. Our results demonstrate therefore that LLS does not contribute to L. monocytogenes tissue injury and virulence in inner host organs as previously reported. Moreover, we describe that LlsB, a putative posttranslational modification enzyme encoded in the LLS operon, is necessary for murine inner organ colonization. Overall, we demonstrate that LLS is the first SLS-like virulence factor targeting exclusively prokaryotic cells during in vivo infections. IMPORTANCE The most severe human listeriosis outbreaks are caused by L. monocytogenes strains harboring listeriolysin S (LLS), previously described as a cytotoxin that plays a critical role in host inner

  12. Virulence Factors and Antibiotic Susceptibility of Staphylococcus aureus Isolates in Ready-to-Eat Foods: Detection of S. aureus Contamination and a High Prevalence of Virulence Genes

    Directory of Open Access Journals (Sweden)

    Suat Moi Puah

    2016-02-01

    Full Text Available Staphylococcus aureus is one of the leading causes of food poisoning. Its pathogenicity results from the possession of virulence genes that produce different toxins which result in self-limiting to severe illness often requiring hospitalization. In this study of 200 sushi and sashimi samples, S. aureus contamination was confirmed in 26% of the food samples. The S. aureus isolates were further characterized for virulence genes and antibiotic susceptibility. A high incidence of virulence genes was identified in 96.2% of the isolates and 20 different virulence gene profiles were confirmed. DNA amplification showed that 30.8% (16/52 of the S. aureus carried at least one SE gene which causes staphylococcal food poisoning. The most common enterotoxin gene was seg (11.5% and the egc cluster was detected in 5.8% of the isolates. A combination of hla and hld was the most prevalent coexistence virulence genes and accounted for 59.6% of all isolates. Antibiotic resistance studies showed tetracycline resistance to be the most common at 28.8% while multi-drug resistance was found to be low at 3.8%. In conclusion, the high rate of S. aureus in the sampled sushi and sashimi indicates the need for food safety guidelines.

  13. MarA, SoxS and Rob function as virulence factors in an Escherichia coli murine model of ascending pyelonephritis.

    Science.gov (United States)

    Casaz, Paul; Garrity-Ryan, Lynne K; McKenney, David; Jackson, Caroline; Levy, Stuart B; Tanaka, S Ken; Alekshun, Michael N

    2006-12-01

    MarA, SoxS and Rob are transcription factors belonging to the AraC family. While these proteins have been associated historically with control of multiple antibiotic resistance, and tolerance to oxidative stress agents and organic solvents, only a paucity of experimental data support a role in regulating virulence. Clinical Escherichia coli isolates, and isogenic strains lacking marA, soxS and rob, were studied in a murine model of ascending pyelonephritis, which is a clinically relevant model of urinary tract infection. Organisms lacking all three transcription factors (triple knockouts) were significantly less virulent than parental strains, and complementation studies demonstrated that the addition of marA, soxS and rob individually restored wild-type virulence in the triple-knockout strain. Deletion of soxS or rob alone was more detrimental than the removal of marA. Thus, all three proteins contribute to virulence in vivo.

  14. Can passage in Galleria mellonella activate virulence factors of Paracoccidioides brasiliensis as in the murine model?

    Science.gov (United States)

    Scorzoni, Liliana; de Paula E Silva, Ana Carolina Alves; de Oliveira, Haroldo Cesar; Marcos, Caroline Maria; Singulani, Junya de Lacorte; Fusco-Almeida, Ana Marisa; Mendes-Giannini, Maria José Soares

    2017-06-15

    Paracoccidioidomycosis (PCM) is a fungal disease restricted to Latin countries, and its etiologic agents derive from the Paracoccidioides genus. Attenuation or loss of virulence in Paracoccidioides spp. following successive subculturing has been described. However, virulence can be recovered by passage in mammalian host. In this study, the recovery of adhesion of P. brasiliensis through passage in mice was compared to that in the insect Galleria mellonella. Analysis of in vitro fungal-host cell interaction, gene expression of adhesins, and analysis of the survival curves revealed that Galleria mellonella is useful for the reactivation of P. brasiliensis adhesion. © The Author 2017. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. Automated 5 ' nuclease assay for detection of virulence factors in porcine Escherichia coli

    DEFF Research Database (Denmark)

    Frydendahl, K.; Imberechts, H.; Lehmann, S.

    2001-01-01

    (STa, STb, EAST1) and heat labile LT) enterotoxins and the verocytotoxin variant 2e (VT2e). To correctly identify false negative results, an endogenous internal control targeting the E. coil 16S rRNA gene was incorporated in each test tube. The assay was evaluated using a collection of E. coil...... reference strains which have previously been examined with phenotypical assays or DNA hybridization. Furthermore, the assay was evaluated by testing porcine E. coil field strains, previously characterized. The 5' nuclease assay correctly detected the presence of virulence genes in all reference strains....... When testing field strains there was generally excellent agreement with results obtained by laboratories in Belgium and Germany. In conclusion, the 5' nuclease assay developed is a fast and specific tool for detection of E. coli virulence genes in the veterinary diagnostic laboratory....

  16. 53 review article a review of the virulence factors of pathogenic fungi

    African Journals Online (AJOL)

    boaz

    such as UV radiation, increased temperature and ROS. The ability to ... aident à la survie des champignons et la persistance dans l'hôterésultant dans les dommages des tissus et la maladie. Cette ... également un facteur de virulence et la calcineurine agit en tant que capteur pour les champignons pathogènes. Mots clés: ...

  17. Fatores de virulência em linhagens de Escherichia coli isoladas de mastite bovina Virulence factors in Escherichia coli strains isolated from bovine mastitis

    Directory of Open Access Journals (Sweden)

    M.G. Ribeiro

    2006-10-01

    Full Text Available Avaliou-se a ocorrência de fatores de virulência e do sorotipo O157:H7 em 120 linhagens de Escherichia coli, isoladas de 80 casos de mastite clínica bovina e 40 de mastite subclínica. Verificou-se alfa-hemolisina em oito (6,7% linhagens, isoladas de cinco casos de mastite clínica e três de mastite subclínica e em nenhuma das estirpes detectou-se enteroemolisina. A presença de sideróforos foi encontrada em 11 (9,2% linhagens, sete de mastite clínica e quatro de subclínica. Em duas (1,7% estirpes isoladas de mastite subclínica, identificou-se enterotoxina STa. Observou-se efeito citopático em células vero compatível com a produção de verotoxina-VT em cinco (4,2% linhagens, duas de mastite clínica e três subclínicas. Em uma (0,8% linhagem isolada de mastite clínica, detectou-se efeito citopático compatível com o fator necrosante citotóxico. Nenhuma estirpe apresentou-se sorbitol-negativa no MacConkey-sorbitol, tampouco aglutinou com o sorotipo O157:H7. Os antimicrobianos mais efetivos foram polimixina B (97,5% e norfloxacina (95,8%. Observou-se multi-resistência a dois ou mais antimicrobianos em 24 (20% estirpes, principalmente com o uso de ampicilina e ceftiofur.The occurrence of different virulence factors and O157:H7 serotype investigation in 120 Escherichia coli strains isolated from clinical (80 cases and subclinical (40 cases bovine mastitis was evaluated. Alpha-haemolysin was detected in 8 (6.7% strains (5 clinical and 3 subclinical cases. None strain showed enterohaemolysin production. E. coli growth under iron restriction conditions (siderophores production was observed in 11 (9.2% strains (7 clinical and 4 subclinical cases. STa enterotoxin was detected in 2 (1.7% strains from subclinical cases. Cytotoxic effect in vero cells compatible with verotoxin-VT production was observed in 5 (4.2% strains (2 clinical and 3 subclinical cases. One strain (0.8% isolated from clinical mastitis showed cytophatic effect in vero

  18. VIRULANCE FACTOR OF Staphylococcus sp. ISOLATED FROM SUBCLINICAL MASTITIS IN ETTAWA GRADE GOAT’S MILK IN SLEMAN REGENCY -YOGYAKARTA

    Directory of Open Access Journals (Sweden)

    W. Suwito

    2014-09-01

    Full Text Available Stapphylococcus sp., is bacteria that caused subclinical mastitis in Ettawa Grade (EG goat. Thepurpose of this study was to determine virulance factor Stapphylococcus sp., which was isolated fromsubclinical mastitis EG goat’s milk in Sleman regency, Yogyakarta. A total of 7 isolate Stapphylococcussp., were isolated from subclinical mastitis EG goat’s milk were determinated by several virulancefactors such as haemolysin, clumping factor, and coagulase. Haemolysin was determinated by culture inblood agar plate and incubated in the temperature of 37°C for 24 hours. Clumping factor wasdeterminated by mixing the rabbit plasma with Stapphylococcus sp., in the glass objects. Coagulase wasdeterminated by mixing the rabbit plasma and broth culture of Stapphylococcus sp. After incubated inthe temperature of 37°C for 24 hours in tube, then the gel formation was observed. Haemolytic type ßwas yielded from 5 isolate Stapphylococcus sp., whereas 2 isolates were not haemolytic. Clumpingfactor and coagulase were produced from 2 isolate Stapphylococcus sp. This study showed that not all ofStapphylococcus sp., isolate causing subclinical mastitis in EG goat have virulance factor.

  19. Human extraintestinal pathogenic Escherichia coli strains differ in prevalence of virulence factors, phylogroups, and bacteriocin determinants.

    Science.gov (United States)

    Micenková, Lenka; Bosák, Juraj; Vrba, Martin; Ševčíková, Alena; Šmajs, David

    2016-09-20

    The study used a set of 407 human extraintestinal pathogenic E. coli strains (ExPEC) isolated from (1) skin and soft tissue infections, (2) respiratory infections, (3) intra-abdominal infections, and (4) genital smears. The set was tested for bacteriocin production, for prevalence of bacteriocin and virulence determinants, and for phylogenetic typing. Results obtained from the group of ExPEC strains were compared to data from our previously published analyses of 1283 fecal commensal E. coli strains. The frequency of bacteriocinogeny was significantly higher in the set of ExPEC strains (63.1 %), compared to fecal E. coli (54.2 %; p production of microcin M and lower production of microcin B17, colicin Ib, and Js was detected in the set of ExPEC strains. ExPEC strains had a significantly higher prevalence of phylogenetic group B2 (52.6 %) compared to fecal E. coli strains (38.3 %; p bacteriocin production, prevalence of several bacteriocin and virulence determinants, and prevalence of phylogenetic groups. Differences in these parameters were also identified within subgroups of ExPEC strains of diverse origin. While some microcin determinants (mM, mH47) were associated with virulent strains, other bacteriocin types (mB17, Ib, and Js) were associated with fecal flora.

  20. The Colletotrichum graminicola striatin orthologue Str1 is necessary for anastomosis and is a virulence factor.

    Science.gov (United States)

    Wang, Chih-Li; Shim, Won-Bo; Shaw, Brian D

    2016-08-01

    Striatin family proteins are key regulators in signalling pathways in fungi and animals. These scaffold proteins contain four conserved domains: a caveolin-binding domain, a coiled-coil motif and a calmodulin-binding domain at the N-terminus, and a WD-repeat domain at the C-terminus. Fungal striatin orthologues are associated with sexual development, hyphal growth and plant pathogenesis. In Fusarium verticillioides, the striatin orthologue Fsr1 promotes virulence in the maize stalk. The relationship between fungal striatins and pathogenicity remains largely unexplored. In this study, we demonstrate that the Colletotrichum graminicola striatin orthologue Str1 is required for full stalk rot and leaf blight virulence in maize. Pathogenicity assays show that the striatin mutant strain (Δstr1) produces functional appressoria, but infection and colonization are attenuated. Additional phenotypes of the Δstr1 mutant include reduced radial growth and compromised hyphal fusion. In comparison with the wild-type, Δstr1 also shows a defect in sexual development and produces fewer and shorter conidia. Together with the fact that F. verticillioides fsr1 can complement Δstr1, our results indicate that C. graminicola Str1 shares five phenotypes with striatin orthologues in other fungal species: hyphal growth, hyphal fusion, conidiation, sexual development and virulence. We propose that fungal striatins, like mammalian striatins, act as scaffolding molecules that cross-link multiple signal transduction pathways. © 2015 BSPP AND JOHN WILEY & SONS LTD.

  1. A DNA pooling based system to detect Escherichia coli virulence factors in fecal and wastewater samples

    Science.gov (United States)

    Luz María Chacón, J; Lizeth Taylor, C; Carmen Valiente, A; Irene Alvarado, P; Ximena Cortés, B

    2012-01-01

    The availability of a useful tool for simple and timely detection of the most important virulent varieties of Escherichia coli is indispensable. To this end, bacterial DNA pools which had previously been categorized were obtained from isolated colonies as well as selected in terms of utilized phenotype; the pools were assessed by two PCR Multiplex for the detection of virulent E. coli eaeA, bfpA, stx1, stx2, ipaH, ST, LT, and aatA genes, with the 16S gene used as DNA control. The system was validated with 66 fecal samples and 44 wastewater samples. At least one positive isolate was detected by a virulent gene among the 20 that were screened. The analysis of fecal samples from children younger than 6 years of age detected frequencies of 25% LT positive strains, 8.3% eae, 8.3% bfpA, 16.7% ipaH, as well as 12.5 % aatA and ST. On the other hand, wastewater samples revealed frequencies of 25.7% eaeA positive, 30.3% stx1, 15.1% LT and 19.7% aatA. This study is an initial step toward carrying out epidemiological field research that will reveal the presence of these bacterial varieties. PMID:24031959

  2. Inhibitory Effects of Chrysanthemum boreale Essential Oil on Biofilm Formation and Virulence Factor Expression of Streptococcus mutans

    Directory of Open Access Journals (Sweden)

    Beom-Su Kim

    2015-01-01

    Full Text Available The aim of the study was to evaluate the antibacterial activity of essential oil extracted from Chrysanthemum boreale (C. boreale on Streptococcus mutans (S. mutans. To investigate anticariogenic properties, and bacterial growth, acid production, biofilm formation, bacterial adherence of S. mutans were evaluated. Then gene expression of several virulence factors was also evaluated. C. boreale essential oil exhibited significant inhibition of bacterial growth, adherence capacity, and acid production of S. mutans at concentrations 0.1–0.5 mg/mL and 0.25–0.5 mg/mL, respectively. The safranin staining and scanning electron microscopy results showed that the biofilm formation was also inhibited. The result of live/dead staining showed the bactericidal effect. Furthermore, real-time PCR analysis showed that the gene expression of some virulence factors such as gtfB, gtfC, gtfD, gbpB, spaP, brpA, relA, and vicR of S. mutans was significantly decreased in a dose dependent manner. In GC and GC-MS analysis, seventy-two compounds were identified in the oil, representing 85.42% of the total oil. The major components were camphor (20.89%, β-caryophyllene (5.71%, α-thujone (5.46%, piperitone (5.27%, epi-sesquiphellandrene (5.16%, α-pinene (4.97%, 1,8-cineole (4.52%, β-pinene (4.45%, and camphene (4.19%. These results suggest that C. boreale essential oil may inhibit growth, adhesion, acid tolerance, and biofilm formation of S. mutans through the partial inhibition of several of these virulence factors.

  3. Inhibitory Effects of Chrysanthemum boreale Essential Oil on Biofilm Formation and Virulence Factor Expression of Streptococcus mutans.

    Science.gov (United States)

    Kim, Beom-Su; Park, Sun-Ju; Kim, Myung-Kon; Kim, Young-Hoi; Lee, Sang-Bong; Lee, Kwang-Hee; Choi, Na-Young; Lee, Young-Rae; Lee, Young-Eun; You, Yong-Ouk

    2015-01-01

    The aim of the study was to evaluate the antibacterial activity of essential oil extracted from Chrysanthemum boreale (C. boreale) on Streptococcus mutans (S. mutans). To investigate anticariogenic properties, and bacterial growth, acid production, biofilm formation, bacterial adherence of S. mutans were evaluated. Then gene expression of several virulence factors was also evaluated. C. boreale essential oil exhibited significant inhibition of bacterial growth, adherence capacity, and acid production of S. mutans at concentrations 0.1-0.5 mg/mL and 0.25-0.5 mg/mL, respectively. The safranin staining and scanning electron microscopy results showed that the biofilm formation was also inhibited. The result of live/dead staining showed the bactericidal effect. Furthermore, real-time PCR analysis showed that the gene expression of some virulence factors such as gtfB, gtfC, gtfD, gbpB, spaP, brpA, relA, and vicR of S. mutans was significantly decreased in a dose dependent manner. In GC and GC-MS analysis, seventy-two compounds were identified in the oil, representing 85.42% of the total oil. The major components were camphor (20.89%), β-caryophyllene (5.71%), α-thujone (5.46%), piperitone (5.27%), epi-sesquiphellandrene (5.16%), α-pinene (4.97%), 1,8-cineole (4.52%), β-pinene (4.45%), and camphene (4.19%). These results suggest that C. boreale essential oil may inhibit growth, adhesion, acid tolerance, and biofilm formation of S. mutans through the partial inhibition of several of these virulence factors.

  4. A Conserved Peptide Pattern from a Widespread Microbial Virulence Factor Triggers Pattern-Induced Immunity in Arabidopsis

    Science.gov (United States)

    Oome, Stan; Raaymakers, Tom M.; Van den Ackerveken, Guido; Nürnberger, Thorsten

    2014-01-01

    Microbe- or host damage-derived patterns mediate activation of pattern-triggered immunity (PTI) in plants. Microbial virulence factor (effector)-triggered immunity (ETI) constitutes a second layer of plant protection against microbial attack. Various necrosis and ethylene-inducing peptide 1 (Nep1)-like proteins (NLPs) produced by bacterial, oomycete and fungal microbes are phytotoxic virulence factors that exert immunogenic activities through phytotoxin-induced host cell damage. We here show that multiple cytotoxic NLPs also carry a pattern of 20 amino acid residues (nlp20) that triggers immunity-associated plant defenses and immunity to microbial infection in Arabidopsis thaliana and related plant species with similar characteristics as the prototype pattern, bacterial flagellin. Characteristic differences in flagellin and nlp20 plant responses exist however, as nlp20s fail to trigger extracellular alkalinization in Arabidopsis cell suspensions and seedling growth inhibition. Immunogenic nlp20 peptide motifs are frequently found in bacterial, oomycete and fungal NLPs. Such an unusually broad taxonomic distribution within three phylogenetic kingdoms is unprecedented among microbe-derived triggers of immune responses in either metazoans or plants. Our findings suggest that cytotoxic NLPs carrying immunogenic nlp20 motifs trigger PTI in two ways as typical patterns and by inflicting host cell damage. We further propose that conserved structures within a microbial virulence factor might have driven the emergence of a plant pattern recognition system mediating PTI. As this is reminiscent of the evolution of immune receptors mediating ETI, our findings support the idea that there is a continuum between PTI and ETI. PMID:25375108

  5. Leaf Extracts of Mangifera indica L. Inhibit Quorum Sensing – Regulated Production of Virulence Factors and Biofilm in Test Bacteria

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    Iqbal Ahmad

    2017-04-01

    Full Text Available Quorum sensing (QS is a global gene regulatory mechanism in bacteria for various traits including virulence factors. Disabling QS system with anti-infective agent is considered as a potential strategy to prevent bacterial infection. Mangifera indica L. (mango has been shown to possess various biological activities including anti-QS. This study investigates the efficacy of leaf extracts on QS-regulated virulence factors and biofilm formation in Gram negative pathogens. Mango leaf (ML extract was tested for QS inhibition and QS-regulated virulence factors using various indicator strains. It was further correlated with the biofilm inhibition and confirmed by electron microscopy. Phytochemical analysis was carried out using ultra performance liquid chromatography (UPLC and gas chromatography–mass spectrometry (GC-MS analysis. In vitro evaluation of anti-QS activity of ML extracts against Chromobacterium violaceum revealed promising dose-dependent interference in violacein production, by methanol extract. QS inhibitory activity is also demonstrated by reduction in elastase (76%, total protease (56%, pyocyanin (89%, chitinase (55%, exopolysaccharide production (58% and swarming motility (74% in Pseudomonas aeruginosa PAO1 at 800 μg/ml concentration. Biofilm formation by P. aeruginosa PAO1 and Aeromonas hydrophila WAF38 was reduced considerably (36–82% over control. The inhibition of biofilm was also observed by scanning electron microscopy. Moreover, ML extracts significantly reduced mortality of Caenorhabditis elegans pre-infected with PAO1 at the tested concentration. Phytochemical analysis of active extracts revealed very high content of phenolics in methanol extract and a total of 14 compounds were detected by GC-MS and UPLC. These findings suggest that phytochemicals from the ML could provide bioactive anti-infective and needs further investigation to isolate and uncover their therapeutic efficacy.

  6. In silico assessment of virulence factors in strains of Streptococcus oralis and Streptococcus mitis isolated from patients with Infective Endocarditis

    DEFF Research Database (Denmark)

    Rasmussen, Louise H.; Iversen, Katrine Højholt; Dargis, Rimtas

    2017-01-01

    Streptococcus oralis and Streptococcus mitis belong to the Mitis group, which are mostly commensals in the human oral cavity. Even though S. oralis and S. mitis are oral commensals, they can be opportunistic pathogens causing infective endocarditis. A recent taxonomic re-evaluation of the Mitis...... group has embedded the species Streptococcus tigurinus and Streptococcus dentisani into the species S. oralis as subspecies. In this study, the distribution of virulence factors that contribute to bacterial immune evasion, colonization and adhesion was assessed in clinical strains of S. oralis (subsp...

  7. Quorum sensing signals are produced by Aeromonas salmonicida and quorum sensing inhibitors can reduce production of a potential virulence factor

    DEFF Research Database (Denmark)

    Rasch, Maria; Kastbjerg, Vicky Gaedt; Bruhn, Jesper Bartholin

    2007-01-01

    of Aeromonas salmonicida strains. All 31 typical strains were AHL producers as were 21 of 26 atypical strains, but on a strain population basis, production of virulence factors such as protease, lipase, A-layer or pigment did not correlate with the production and accumulation of AHLs in the growth medium....... Pigment production was only observed in broth under highly aerated conditions. Quorum sensing inhibitors (QSIs) are compounds that specifically block QS systems without affecting bacterial growth and 2 such compounds, sulphur-containing AHL-analogues, reduced production of protease in a typical strain...

  8. Effect of antibiotic prophylaxis on Coagulase-negative Staphylococcus virulence factor profiles in patients undergoing cataract surgery.

    Science.gov (United States)

    López, Yolanda; Samudio, Margarita; Fariña, Norma; Castillo, Verónica; Abente, Sonia; Nentwich, Martin M; González-Britez, Nilsa; Laspina, Florentina; Carron, Agustín; Cibils, Diógenes; de Kaspar, Herminia Miño

    2017-08-01

    In this prospective study, multiplex polymerase chain reaction (PCR) was used to identify genes encoding virulence factors (ica, atlE and mecA) in Coagulase-negative Staphylococcus (CNS) isolates from the ocular microbiota of patients undergoing cataract surgery and to investigate possible changes in the CNS profile due to antibiotic prophylaxis. Between 09/2011 and 08/2013, patients undergoing cataract surgery were recruited at the Department of Ophthalmology, National University of Asuncion, Paraguay. In the eye to be operated on, patients received moxifloxacin 0.5 % eye drops four times at the day before surgery and a last drop 1 hour before surgery (T1). The other eye remained as control (T0). Conjunctival swabs were taken from both eyes 1 hour after the last drop. The presence of genes encoding biofilm formation (ica and atlE) and methicillin resistance (mecA) was detected by a multiplex PCR. Of the 162 patients (162 study eyes, 162 fellow eye as control group), 87 (53.7 %) eyes were positive for CNS at T0 yielding 96 CNS isolates; 70 eyes (43.2 %) were positive at T1 yielding 77 CNS isolates. For this study, 43 CNS isolates (44.8 %) from T0 and 45 (64.3 %) from T1 were used. Of the total isolates, 81.8 % (72/88) had at least one virulence factor gene (37/43 from T0 and 35/45 from T1) (p = 0.314). Simultaneous detection of ica and atlE genes was higher in T0 (58.0 %) than T1 (46.7 %), but the difference was not significant (p = 0.28). A high frequency of genes encoding virulence factors was observed in the coagulase-negative Staphylococcus isolates. The use of moxifloxacin did not significantly modify the CNS virulence factor profiles.

  9. S. aureus hemolysins, bi-component leukocidins and cytolytic peptides: a redundant arsenal of membrane-damaging virulence factors?

    Directory of Open Access Journals (Sweden)

    Francois eVandenesch

    2012-02-01

    Full Text Available One key aspect of S. aureus virulence lies in its ability to target the host cell membrane with a large number of membrane-damaging toxins and peptides. In this review, we describe the hemolysins, the bi-component leukocidins, which include the Panton Valentine Leukocidin, LukAB/GH, LukED and the cytolytic peptides (Phenol Soluble Modulins. While at first glance, all these factors might appear redundant, it is now clear that some of these factors play specific roles in certain S. aureus life stages and diseases or target specific cell types or species. Here, we present an update of the literature on toxins receptors and their cell type and species specificities. Furthermore, we review epidemiological studies and animal models illustrating a role of these membrane-damaging factors in various diseases. Finally, we emphasize the interplay of these factors with the host immune system and highlight all their non-lytic functions.

  10. The microRNA biogenesis machinery: regulation by steroid hormones and alterations in cancer.

    Science.gov (United States)

    González-Duarte, Ramiro José; Cázares-Ordoñez, Verna; Ávila-Chávez, Euclides

    2014-01-01

    MicroRNAs are a class of non-coding RNAs that regulate gene expression at the post-transcriptional level. The major proteins of the canonical microRNA biogenesis pathway in human are: Drosha, DGCR8, DDX5, DDX17, Exportin 5, Dicer and Argonaute 2. Recent studies suggest that gene expression of some canonical microRNA biogenesis components could be regulated by steroid hormones. Furthermore, various alterations in microRNA biogenesis have been associated with diseases like cancer. Due to the importance of microRNAs in cell physiology, the study of the factors that regulate or affect their biogenesis is critical.

  11. Inhibition of pyrimidine synthesis reverses viral virulence factor-mediated block of mRNA nuclear export.

    Science.gov (United States)

    Zhang, Liang; Das, Priyabrata; Schmolke, Mirco; Manicassamy, Balaji; Wang, Yaming; Deng, Xiaoyi; Cai, Ling; Tu, Benjamin P; Forst, Christian V; Roth, Michael G; Levy, David E; García-Sastre, Adolfo; de Brabander, Jef; Phillips, Margaret A; Fontoura, Beatriz M A

    2012-02-06

    The NS1 protein of influenza virus is a major virulence factor essential for virus replication, as it redirects the host cell to promote viral protein expression. NS1 inhibits cellular messenger ribonucleic acid (mRNA) processing and export, down-regulating host gene expression and enhancing viral gene expression. We report in this paper the identification of a nontoxic quinoline carboxylic acid that reverts the inhibition of mRNA nuclear export by NS1, in the absence or presence of the virus. This quinoline carboxylic acid directly inhibited dihydroorotate dehydrogenase (DHODH), a host enzyme required for de novo pyrimidine biosynthesis, and partially reduced pyrimidine levels. This effect induced NXF1 expression, which promoted mRNA nuclear export in the presence of NS1. The release of NS1-mediated mRNA export block by DHODH inhibition also occurred in the presence of vesicular stomatitis virus M (matrix) protein, another viral inhibitor of mRNA export. This reversal of mRNA export block allowed expression of antiviral factors. Thus, pyrimidines play a necessary role in the inhibition of mRNA nuclear export by virulence factors. © 2012 Zhang et al.

  12. Fatores de virulência presentes em amostras de Escherichia coli uropatogênicas - UPEC para suínos Virulence factors of uropathogenic Escherichia coli - UPEC strains for pigs

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    Benito Guimarães de Brito

    2004-04-01

    Full Text Available As infecções urinárias são freqüentes nos rebanhos suínos, sendo a principal causa de descarte e mortalidade de animais adultos. Apesar das características multifatoriais da doença o microrganismo freqüentemente isolado é a Escherichia coli. Vários fatores de virulência de Escherichia coli foram descritos em amostras uropatogênicas e permitem diferenciar cepas patogênicas de não patogênicas. Esta revisão tem por objetivo apresentar alguns tópicos relativos aos fatores de virulência presentes em amostras de E. coli uropatogênicas para suínos.Urinary tract infections occur frequently in pig herds urinary infection is the most significant cause of culling and mortality of adult animals. Despite the multifactorial nature of this condition, Escherichia coli is frequently isolated from diseased animals. Several virulence factors were described on uropathogenic strains and they can be used to distinguish isolates. The objective of the present review is to present some topics related to virulence factors present in swine uropathogenic E. coli strains.

  13. Genotypic Characterization of Virulence Factors in Escherichia coli Isolated from Patients with Acute Cystitis, Pyelonephritis and Asymptomatic Bacteriuria.

    Science.gov (United States)

    Tabasi, Mohsen; Karam, Mohammad Reza Asadi; Habibi, Mehri; Mostafavi, Ehsan; Bouzari, Saeid

    2016-12-01

    Urinary Tract Infections (UTIs) caused by Uropathogenic Escherichia coli (UPEC) are among the most common infections worldwide. It is well-documented that the pathogenesis of UPEC is mediated by the production of a wide variety of Virulence Factors (VFs). Thus, detection of these VFs and evaluation of their association with different clinical types of UTIs could help to understand the role of these factors in pathogenesis of UPEC isolates. To investigate the genotypic characteristics of UPEC isolates and to examine the relationship between VFs and different clinical symptoms of UTI. In this cross-sectional study conducted at Pasteur Institute of Iran, a total of 156 UPEC isolated from outpatients and inpatients (symptomatic and asymptomatic UTI patients) visiting general and private hospitals in Tehran, Iran between March 2014 and February 2015 were included. Among them, 49 patients experienced at least one episode of recurrent UTI. A Polymerase Chain Reaction (PCR) assay was developed to detect the presence of different VFs in the isolates. Moreover, Pulsed-Field Gel Electrophoresis (PFGE) was used to characterize clonal relationships among UPEC isolates. The prevalence of virulence genes ranged from 0% for cdtB to 100% for fimH. The papEF, hlyA and aer genes were found to be significantly more frequent in UPEC isolated from patients with pyelonephritis, while the afa gene, the only indicator of recurrent UTIs, was more prevalent in UPEC isolated from patients with cystitis. In the present study, 34 PFGE clonal groups were found in the UPEC genome. Our findings showed that from outpatients and patients with pyelonephritis, isolates were more virulent than those isolated from inpatients and cystitis patients, respectively. PFGE displayed a large diversity in the UPEC isolates that could be considered as an evolutionary strategy in the survival of the bacteria.

  14. Attenuation of quorum-sensing-dependent virulence factors and biofilm formation by medicinal plants against antibiotic resistant Pseudomonas aeruginosa

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    P. Sankar Ganesh

    2018-01-01

    Full Text Available Pseudomonas aeruginosa use small signaling molecules such as acyl homoserine lactones (AHLs, which play an important role in release virulence factors and toxin for further establishment of host infection. Thus, involving with the QS system would provide alternative ways of preventing the pathogenicity. In the present study, totally six medicinal plants (Terminalia bellerica, Celastrus paniculatus, Kingiodendron pinnatum, Schleichera oleosa, Melastoma malabathricum, Garcinia gummi-gutta were screened for anti-QS activity using biomonitor strain of Chromobacterium violaceum CV12472. The primary screening of antimicrobial activity of all the plant extracts have inhibited the growth of tested bacterial species. Of these at the sub-minimum inhibitory concentration the methanol extract of T. bellerica (0.0625–0.5 mg/ml has significantly inhibited violacein production (20.07–66.22% in C. violaceum (CV12472. Consequently, the extract of T. bellerica has reduced the production of pyocyanin, exopolysaccharide and biofilm formation in P. aeruginosa strains. Fluorescence and scanning electron microscopy analysis confirmed the reduction of biofilm formation in P. aeruginosa strains when treated with T. bellerica. GC–MS analysis showed the active compounds inhibited the production of virulence factors of P. aeruginosa. The results suggest the possible use of this T. bellerica as an anti-QS and anti-biofilm agent to control Pseudomonas infection. Interference of QS provides an important means for the inhibition of bacterial virulence and thus aids in treatment strategies.

  15. The Fungal bZIP Transcription Factor AtfB Controls Virulence-Associated Processes in Aspergillus parasiticus

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    Josephine Wee

    2017-09-01

    Full Text Available Fungal basic leucine zipper (bZIP transcription factors mediate responses to oxidative stress. The ability to regulate stress response pathways in Aspergillus spp. was postulated to be an important virulence-associated cellular process, because it helps establish infection in humans, plants, and animals. Previous studies have demonstrated that the fungal transcription factor AtfB encodes a protein that is associated with resistance to oxidative stress in asexual conidiospores, and AtfB binds to the promoters of several stress response genes. Here, we conducted a gene silencing of AtfB in Aspergillus parasiticus, a well-characterized fungal pathogen of plants, animals, and humans that produces the secondary metabolite and carcinogen aflatoxin, in order to determine the mechanisms by which AtfB contributes to virulence. We show that AtfB silencing results in a decrease in aflatoxin enzyme levels, the down-regulation of aflatoxin accumulation, and impaired conidiospore development in AtfB-silenced strains. This observation is supported by a decrease of AtfB protein levels, and the down-regulation of many genes in the aflatoxin cluster, as well as genes involved in secondary metabolism and conidiospore development. Global expression analysis (RNA Seq demonstrated that AtfB functionally links oxidative stress response pathways to a broader and novel subset of target genes involved in cellular defense, as well as in actin and cytoskeleton arrangement/transport. Thus, AtfB regulates the genes involved in development, stress response, and secondary metabolism in A. parasiticus. We propose that the bZIP regulatory circuit controlled by AtfB provides a large number of excellent cellular targets to reduce fungal virulence. More importantly, understanding key players that are crucial to initiate the cellular response to oxidative stress will enable better control over its detrimental impacts on humans.

  16. Occurrence Of Virulence Factors And Antimicrobial Resistance In Pasteurella Multocida Strains Isolated From Slaughter Cattle In Iran

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    Faham eKhamesipour

    2014-10-01

    Full Text Available A total of 30 Pasteurella multocida strains isolated from 333 pneumonic and apparently health slaughter cattle were examined for capsule biosynthesis genes and 23 virulence associated genes by polymerase chain reaction. The disc diffusion technique was used to determine antimicrobial resistance profiles among the isolates. Of the isolates, 23 belonged to capsular type A, 5 to capsular type D and two isolates were untypeable. The distribution of the capsular types in pneumonic lungs and in apparently health lungs was statistically similar. All virulence genes tested were detected among the isolates derived from pneumonic lungs; whereas isolates derived from apparently health lungs carried 16 of the 23 genes. The frequently detected genes among isolates from pneumonic lungs were exbD, hgbA, hgbB, ompA, ompH, oma87 and sodC; whereas tadD, toxA and pmHAS genes occurred less frequently. Most of the adhesins and superoxide dismutases; and all of the iron acquisition and protectin proteins occurred at significantly (p≤0.05 higher frequencies in isolates from pneumonic lungs. Isolates from apparently healthy lungs didn’t carry the following genes; hsf-1, hsf-2, tadD, toxA, nanB, nanH and pmHAS. One adhesion (hsf-1 and two iron acquisition (exbD and tonB genes occurred at significantly (p≤0.05 higher frequencies among capA isolates. All the P. multocida isolates were susceptible to ciprofloxacin, co-trimoxazole, doxycycline, enrofloxacin, nitrofurantoin and tetracyclines. Different proportions of the isolates were however resistant to ampicillin, amoxicillin, erythromycin, lincomycin, penicillin, rifampin, streptomycin and florfenicol. Our results reveal presence of virulence factors in P. multocida strains isolated from symptomatic and asymptomatic bovids. A higher frequency of the factors among isolates from symptomatic study animals may suggest their role in pathogenesis of P. multocida-associated bovine respiratory disease. The results further

  17. Sub-MICs of Carum copticum and Thymus vulgaris influence virulence factors and biofilm formation in Candida spp.

    Science.gov (United States)

    Khan, Mohd S A; Ahmad, Iqbal; Cameotra, Swaranjit S; Botha, Francien

    2014-09-15

    Emergence of drug-resistant strains of Candida and inefficiency of conventional antifungal therapy has necessitated the search for alternative and new antifungal agents. Inhibition of virulence and biofilm are the potential drug targets. In this study, the oils of Carum copticum, Thymus vulgaris and their major active compound thymol as revealed by Gas chromatography and gas chromatography-mass spectrometry (GC-GC/MS) analysis were tested for their inhibitory activity against growth to determine sub-MIC values against 27 drug-resistant strains of Candida spp. Brothmacrodilution method was used for determination of MIC of test oils against Candida strains. The spectrophotometric methods were used for detection and inhibition assays for virulence factors in Candida spp. Light and electron microscopy was performed to observe morphological effects of oils on biofilms. GC-GC/MS were used to evaluate the major active compounds of test oils. Virulence factors like proteinase and haemolysin were detected in 18 strains, both in solid and liquid media. A 70% of the test strains exhibited hydrophobicity and formed moderate to strong biofilms (OD280 0.5- > 1.0). Test oils exhibited MICs in the range of 45-360 μg.mL(-1) against the majority of test strains. All the oils at 0.25× and 0.5× MICs induced >70% reduction in the cell surface hydrophobicity, proteinase and haemolysin production. At 0.5× MIC, thymol and T. vulgaris were most inhibitory against biofilm formation. At sub-MICs electron microscopic studies revealed the deformity of complex structures of biofilms formed and cell membranes appeared to be the target site of these agents. Therefore, our findings have highlighted the concentration dependent activity of oils of C. copticum and T. vulgaris against virulence factors and biofilms in proteinase and haemolysin producing drug-resistant strains of Candida spp. The above activities of test oils are supposed to be mainly contributed due to their major active

  18. Hemolysin activities as virulence factor of Enterococcus faecalis isolated from saliva and periapical abscess (gene detection by PCR

    Directory of Open Access Journals (Sweden)

    Dewa Ayu N.P.A

    2013-03-01

    Full Text Available Background: Enterococcus faecalis is a normal flora of the oral cavity, commonly detected in saliva and persistence in endodontic infections. These bacteria have diverse survival and virulence factors. Hemolysin is one of the factor and still had unclear role as a virulence factor of the Enterococcus faecalis to survive in the root canal. Purpose: The purpose of this research was to analyze the presence and activity of hemolysin gene and its activity as a virulence factor isolated from saliva and root canals with periapical abscess. Yet by understanding one of the phenotypes characters which is hemolysin, it is expected a successful endodontic treatment can be provided with the persistent of Enterococcus faecalis bacteria. Methods: Method of the research starting with the identification of Enterococcus faecalis bacteria in isolated saliva and periapical abscess was done in the first part of the study. Then the phenotypes character of Enterococcus faecalis such as gene detection and expression of hemolysin in blood agar cultures of the 60 colonies samples were performed in the later part. Results: Not all of the colonies cultured were identified as Enterococcus faecalis. All positive detection on hemolysin gene showed hemolysin expresion in both isolated samples. However, there were samples with hemolysin expression eventough no hemolysin gene detected. Hemolysin expression detection in saliva was higher due to different activation phase of hemolysin in saliva. The study with just one primer could lead to the possibility of undetected hemolysin gene, eventough there were samples that did not have hemolysin gene. The proportion of hemolysin expression in root canals were less than saliva, this could be influenced by environmental factors. However, Hemolysin was considered as important virulence factor, particularly for disease therapy. Conclusion: The conclusion of this research was hemolysin gene discovered in clinical isolated saliva and root

  19. Differential Secretomics of Streptococcus pyogenes Reveals a Novel Peroxide Regulator (PerR)-regulated Extracellular Virulence Factor Mitogen Factor3 (MF3)*

    Science.gov (United States)

    Wen, Yao-Tseng; Tsou, Chih-Cheng; Kuo, Hsin-Tzu; Wang, Jie-Siou; Wu, Jiunn-Jong; Liao, Pao-Chi

    2011-01-01

    Streptococcus pyogenes is a human pathogen that causes various diseases. Numerous virulence factors secreted by S. pyogenes are involved in pathogenesis. The peroxide regulator (PerR) is associated with the peroxide resistance response and pathogenesis, but little is known about the regulation of the secretome involved in virulence. To investigate how PerR regulates the expression of the S. pyogenes secretome involved in virulence, a perR deficient mutant was used for comparative secretomic analysis with a wild-type strain. The conditioned medium containing secreted proteins of a wild-type strain and a perR deficient mutant at the stationary phase were collected for two-dimensional gel electrophoresis analysis, where protease inhibitors were applied to avoid the degradation of extracellular proteins. Differentially expressed protein spots were identified by liquid chromatography electrospray ionization tandem MS. More than 330 protein spots were detected on each gel. We identified 25 unique up-regulated proteins and 13 unique down-regulated proteins that were directly or indirectly controlled by the PerR regulator. Among these identified proteins, mitogen factor 3 (MF3), was selected to verify virulence and the expression of gene products. The data showed that MF3 protein levels in conditioned medium, as measured by immunoblot analysis, correlated well with protein levels determined by two-dimensional gel electrophoresis analysis. We also demonstrated that PerR bound to the promoter region of the mf3 gene. The result of an infection model showed that virulence was attenuated in the mf3 deficient mutant. Additional growth data of the wild-type strain and the mf3 deficient mutant suggested that MF3 played a role in digestion of exogenous DNA for promoting growth. To summarize, we conclude that PerR can positively regulate the expression of the secreted protein MF3 that contributes to the virulence in S. pyogenes. The analysis of the PerR-regulated secretome provided

  20. A Salmonella small non-coding RNA facilitates bacterial invasion and intracellular replication by modulating the expression of virulence factors.

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    Hao Gong

    2011-09-01

    Full Text Available Small non-coding RNAs (sRNAs that act as regulators of gene expression have been identified in all kingdoms of life, including microRNA (miRNA and small interfering RNA (siRNA in eukaryotic cells. Numerous sRNAs identified in Salmonella are encoded by genes located at Salmonella pathogenicity islands (SPIs that are commonly found in pathogenic strains. Whether these sRNAs are important for Salmonella pathogenesis and virulence in animals has not been reported. In this study, we provide the first direct evidence that a pathogenicity island-encoded sRNA, IsrM, is important for Salmonella invasion of epithelial cells, intracellular replication inside macrophages, and virulence and colonization in mice. IsrM RNA is expressed in vitro under conditions resembling those during infection in the gastrointestinal tract. Furthermore, IsrM is found to be differentially expressed in vivo, with higher expression in the ileum than in the spleen. IsrM targets the mRNAs coding for SopA, a SPI-1 effector, and HilE, a global regulator of the expression of SPI-1 proteins, which are major virulence factors essential for bacterial invasion. Mutations in IsrM result in disregulation of expression of HilE and SopA, as well as other SPI-1 genes whose expression is regulated by HilE. Salmonella with deletion of isrM is defective in bacteria invasion of epithelial cells and intracellular replication/survival in macrophages. Moreover, Salmonella with mutations in isrM is attenuated in killing animals and defective in growth in the ileum and spleen in mice. Our study has shown that IsrM sRNA functions as a pathogenicity island-encoded sRNA directly involved in Salmonella pathogenesis in animals. Our results also suggest that sRNAs may represent a distinct class of virulence factors that are important for bacterial infection in vivo.

  1. The Prevalence of Helicobacter pylori Virulence Factors in Bhutan, Vietnam, and Myanmar Is Related to Gastric Cancer Incidence.

    Science.gov (United States)

    Trang, Tran Thi Huyen; Shiota, Seiji; Matsuda, Miyuki; Binh, Tran Thanh; Suzuki, Rumiko; Vilaichone, Ratha-korn; Mahachai, Varocha; Tshering, Lotay; Dung, Ho D Q; Uchida, Tomohisa; Matsunari, Osamu; Myint, Thein; Khien, Vu Van; Yamaoka, Yoshio

    2015-01-01

    Gastric cancer is a significant health problem in Asia. Although the prevalence of Helicobacter pylori infection is similar in Bhutan, Vietnam, and Myanmar, the incidence of gastric cancer is highest in Bhutan, followed by Vietnam and Myanmar. We hypothesized that H. pylori virulence factors contribute to the differences. The status of cagA, vacA, jhp0562, and β-(1,3)galT(jhp0563) was examined in 371 H. pylori-infected patients from Bhutan, Vietnam, and Myanmar. Each virulence factor could not explain the difference of the incidence of gastric cancer. However, the prevalence of quadruple-positive for cagA, vacA s1, vacA m1, and jhp0562-positive/β-(1,3)galT-negative was significantly higher in Bhutan than in Vietnam and Myanmar and correlated with gastric cancer incidence. Moreover, gastritis-staging scores measured by histology of gastric mucosa were significantly higher in quadruple-positive strains. We suggest that the cagA, vacA s1, vacA m1, and jhp0562-positive/β-(1,3)galT-negative genotype may play a role in the development of gastric cancer.

  2. The Prevalence of Helicobacter pylori Virulence Factors in Bhutan, Vietnam, and Myanmar Is Related to Gastric Cancer Incidence

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    Tran Thi Huyen Trang

    2015-01-01

    Full Text Available Gastric cancer is a significant health problem in Asia. Although the prevalence of Helicobacter pylori infection is similar in Bhutan, Vietnam, and Myanmar, the incidence of gastric cancer is highest in Bhutan, followed by Vietnam and Myanmar. We hypothesized that H. pylori virulence factors contribute to the differences. The status of cagA, vacA, jhp0562, and β-(1,3galT(jhp0563 was examined in 371 H. pylori-infected patients from Bhutan, Vietnam, and Myanmar. Each virulence factor could not explain the difference of the incidence of gastric cancer. However, the prevalence of quadruple-positive for cagA, vacA s1, vacA m1, and jhp0562-positive/β-(1,3galT-negative was significantly higher in Bhutan than in Vietnam and Myanmar and correlated with gastric cancer incidence. Moreover, gastritis-staging scores measured by histology of gastric mucosa were significantly higher in quadruple-positive strains. We suggest that the cagA, vacA s1, vacA m1, and jhp0562-positive/β-(1,3galT-negative genotype may play a role in the development of gastric cancer.

  3. Deletion of znuA virulence factor attenuates Brucella abortus and confers protection against wild-type challenge.

    Science.gov (United States)

    Yang, Xinghong; Becker, Todd; Walters, Nancy; Pascual, David W

    2006-07-01

    znuA is known to be an important factor for survival and normal growth under low Zn(2+) concentrations for Escherichia coli, Haemophilus spp., Neisseria gonorrhoeae, and Pasteurella multocida. We hypothesized that the znuA gene present in Brucella melitensis 16 M would be similar to znuA in B. abortus and questioned whether it may also be an important factor for growth and virulence of Brucella abortus. Using the B. melitensis 16 M genome sequence, primers were designed to construct a B. abortus deletion mutant. A znuA knockout mutation in B. abortus 2308 (DeltaznuA) was constructed and found to be lethal in low-Zn(2+) medium. When used to infect macrophages, DeltaznuA B. abortus showed minimal growth. Further study with DeltaznuA B. abortus showed that its virulence in BALB/c mice was attenuated, and most of the bacteria were cleared from the spleen within 8 weeks. Protection studies confirmed the DeltaznuA mutant as a potential live vaccine, since protection against wild-type B. abortus 2308 challenge was as effective as that obtained with the RB51 or S19 vaccine strain.

  4. CRH Affects the Phenotypic Expression of Sepsis-Associated Virulence Factors by Streptococcus pneumoniae Serotype 1 In vitro

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    Colette G. Ngo Ndjom

    2017-06-01

    Full Text Available Sepsis is a life-threatening health condition caused by infectious pathogens of the respiratory tract, and accounts for 28–50% of annual deaths in the US alone. Current treatment regimen advocates the use of corticosteroids as adjunct treatment with antibiotics, for their broad inhibitory effect on the activity and production of pro-inflammatory mediators. However, despite their use, corticosteroids have not proven to be able to reverse the death incidence among septic patients. We have previously demonstrated the potential for neuroendocrine factors to directly influence Streptococcus pneumoniae virulence, which may in turn mediate disease outcome leading to sepsis and septic shock. The current study investigated the role of Corticotropin-releasing hormone (CRH in mediating key markers of pneumococcal virulence as important phenotypic determinants of sepsis and septic shock risks. In vitro cultures of serotype 1 pneumococcal strain with CRH promoted growth rate, increased capsule thickness and penicillin resistance, as well as induced pneumolysin gene expression. These results thus provide significant insights of CRH–pathogen interactions useful in understanding the underlying mechanisms of neuroendocrine factor's role in the onset of community acquired pneumonias (CAP, sepsis and septic shock.

  5. Effect of Cinnamon Oil on Quorum Sensing-Controlled Virulence Factors and Biofilm Formation in Pseudomonas aeruginosa.

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    Manmohit Kalia

    Full Text Available Quorum sensing (QS is a system of stimuli and responses in bacterial cells governed by their population density, through which they regulate genes that control virulence factors and biofilm formation. Despite considerable research on QS and the discovery of new antibiotics, QS-controlled biofilm formation by microorganisms in clinical settings has remained a problem because of nascent drug resistance, which requires screening of diverse compounds for anti-QS activities. Cinnamon is a dietary phytochemical that is traditionally used to remedy digestive problems and assorted contagions, which suggests that cinnamon might contain chemicals that can hinder the QS process. To test this hypothesis, the anti-QS activity of cinnamon oil against P. aeruginosa was tested, measured by the inhibition of biofilm formation and other QS-associated phenomena, including virulence factors such as pyocyanin, rhamnolipid, protease, alginate production, and swarming activity. To this end, multiple microscopy analyses, including light, scanning electron and confocal microscopy, revealed the ability of cinnamon oil to inhibit P. aeruginosa PAO1 biofilms and their accompanying extracellular polymeric substances. This work is the first to demonstrate that cinnamon oil can influence various QS-based phenomena in P. aeruginosa PAO1, including biofilm formation.

  6. Virulence factors of Actinobacillus pleuropneumoniae involved in colonization, persistence and induction of lesions in its porcine host.

    Science.gov (United States)

    Chiers, Koen; De Waele, Tine; Pasmans, Frank; Ducatelle, Richard; Haesebrouck, Freddy

    2010-01-01

    Actinobacillus pleuropneumoniae is the causative agent of porcine pleuropneumonia. The virulence factors of this microorganism involved in colonization and the induction of lung lesions have been thoroughly studied and some have been well characterized. A. pleuropneumoniae binds preferentially to cells of the lower respiratory tract in a process involving different adhesins and probably biofilm formation. Apx toxins and lipopolysaccharides exert pathogenic effects on several host cells, resulting in typical lung lesions. Lysis of host cells is essential for the bacterium to obtain nutrients from the environment and A. pleuropneumoniae has developed several uptake mechanisms for these nutrients. In addition to persistence in lung lesions, colonization of the upper respiratory tract--and of the tonsils in particular--may also be important for long-term persistent asymptomatic infection. Information on virulence factors involved in tonsillar and nasal cavity colonization and persistence is scarce, but it can be speculated that similar features as demonstrated for the lung may play a role. © The authors, published by INRA/EDP Sciences, 2010.

  7. Surface antigens and potential virulence factors from parasites detected by comparative genomics of perfect amino acid repeats

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    Adler Joël

    2007-12-01

    Full Text Available Abstract Background Many parasitic organisms, eukaryotes as well as bacteria, possess surface antigens with amino acid repeats. Making up the interface between host and pathogen such repetitive proteins may be virulence factors involved in immune evasion or cytoadherence. They find immunological applications in serodiagnostics and vaccine development. Here we use proteins which contain perfect repeats as a basis for comparative genomics between parasitic and free-living organisms. Results We have developed Reptile http://reptile.unibe.ch, a program for proteome-wide probabilistic description of perfect repeats in proteins. Parasite proteomes exhibited a large variance regarding the proportion of repeat-containing proteins. Interestingly, there was a good correlation between the percentage of highly repetitive proteins and mean protein length in parasite proteomes, but not at all in the proteomes of free-living eukaryotes. Reptile combined with programs for the prediction of transmembrane domains and GPI-anchoring resulted in an effective tool for in silico identification of potential surface antigens and virulence factors from parasites. Conclusion Systemic surveys for perfect amino acid repeats allowed basic comparisons between free-living and parasitic organisms that were directly applicable to predict proteins of serological and parasitological importance. An on-line tool is available at http://genomics.unibe.ch/dora.

  8. A polydnavirus ANK protein acts as virulence factor by disrupting the function of prothoracic gland steroidogenic cells.

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    Luca Valzania

    Full Text Available Polydnaviruses are obligate symbionts integrated as proviruses in the genome of some ichneumonoid wasps that parasitize lepidopteran larvae. Polydnavirus free viral particles, which are injected into the host at oviposition, express virulence factors that impair immunity and development. To date, most studies have focused on the molecular mechanisms underpinning immunosuppression, whereas how viral genes disrupt the endocrine balance remains largely uninvestigated. Using Drosophila as a model system, the present report analyzes the function of a member of the ankyrin gene family of the bracovirus associated with Toxoneuron nigriceps, a larval parasitoid of the noctuid moth Heliothis virescens. We found that the TnBVank1 expression in the Drosophila prothoracic gland blocks the larval-pupal molt. This phenotype can be rescued by feeding the larvae with 20-hydroxyecdysone. The localization of the TnBVANK1 is restricted to the cytoplasm where it interacts with Hrs and Alix marked endosomes. Collectively, our data demonstrate that the TnBVANK1 protein acts as a virulence factor that causes the disruption of ecdysone biosynthesis and developmental arrest by impairing the vesicular traffic of ecdysteroid precursors in the prothoracic gland steroidogenic cells.

  9. Polygalacturonase gene pgxB in Aspergillus niger is a virulence factor in apple fruit.

    Science.gov (United States)

    Liu, Cheng-Qian; Hu, Kang-Di; Li, Ting-Ting; Yang, Ying; Yang, Feng; Li, Yan-Hong; Liu, He-Ping; Chen, Xiao-Yan; Zhang, Hua

    2017-01-01

    Aspergillus niger, a saprophytic fungus, is widely distributed in soil, air and cereals, and can cause postharvest diseases in fruit. Polygalacturonase (PG) is one of the main enzymes in fungal pathogens to degrade plant cell wall. To evaluate whether the deletion of an exo-polygalacturonase gene pgxB would influence fungal pathogenicity to fruit, pgxB gene was deleted in Aspergillus niger MA 70.15 (wild type) via homologous recombination. The ΔpgxB mutant showed similar growth behavior compared with the wild type. Pectin medium induced significant higher expression of all pectinase genes in both wild type and ΔpgxB in comparison to potato dextrose agar medium. However, the ΔpgxB mutant was less virulent on apple fruits as the necrosis diameter caused by ΔpgxB mutant was significantly smaller than that of wild type. Results of quantitive-PCR showed that, in the process of infection in apple fruit, gene expressions of polygalacturonase genes pgaI, pgaII, pgaA, pgaC, pgaD and pgaE were enhanced in ΔpgxB mutant in comparison to wild type. These results prove that, despite the increased gene expression of other polygalacturonase genes in ΔpgxB mutant, the lack of pgxB gene significantly reduced the virulence of A. niger on apple fruit, suggesting that pgxB plays an important role in the infection process on the apple fruit.

  10. Genetic characterization of antibiotic resistance and virulence factors in Enterococcus spp. from Japanese retail ready-to-eat raw fish.

    Science.gov (United States)

    Hammad, Ahmed M; Shimamoto, Toshi; Shimamoto, Tadashi

    2014-04-01

    Little information is available on the diversity and distribution of resistance and virulence factors in enterococci isolated from retail fish. In this study, 200 samples of retail ready-to-eat raw fish (sashimi) collected from the Japanese prefecture of Hiroshima were analyzed for incidence of Enterococcus spp. We recovered 96 enterococcal isolates from 90 (45%, 90/200) samples. Fifty-six strains were identified at the species level: E. faecalis (n = 31), E. faecium (n = 7), E. casseliflavus (n = 7), E. gallinarum (n = 3), E. phoeniculicola (n = 4), E. raffinosus (n = 2), E. saccharolyticus (n = 1), and E. gilvus (n = 1). Twenty-five (26%, 25/96) strains carried antibiotic resistance genes. These included the tet(M), tet(L), tet(K), erm(B), msr(A/B), aph(3'), and blaZ genes, which were detected in 12.5%, 9.3%, 2%, 14.5%, 1%, 1%, and 2% of isolates, respectively. The virulence genes gelE and asa1 were detected in 31 and 24 E. faecalis strains, respectively. Both genes were detected in one E. faecium strain. In conclusion, this is the first study to underscore the importance of sashimi as not only a reservoir of Enterococcus spp. carrying resistance and virulence genes, but also a reservoir for unusual Enterococcus spp. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Crystal Structure of the LasA Virulence Factor from Pseudomonas aeruginosa: Substrate Specificity and Mechanism of M23 Metallopeptidases

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    Spencer, James; Murphy, Loretta M.; Conners, Rebecca; Sessions, Richard B.; Gamblin, Steven J. (Wales); (Bristol Med Sci); (NIMR)

    2010-09-21

    Pseudomonas aeruginosa is an opportunist Gram-negative bacterial pathogen responsible for a wide range of infections in immunocompromized individuals and is a leading cause of mortality in cystic fibrosis patients. A number of secreted virulence factors, including various proteolytic enzymes, contribute to the establishment and maintenance of Pseudomonas infection. One such is LasA, an M23 metallopeptidase related to autolytic glycylglycine endopeptidases such as Staphylococcus aureus lysostaphin and LytM, and to DD-endopeptidases involved in entry of bacteriophage to host bacteria. LasA is implicated in a range of processes related to Pseudomonas virulence, including stimulating ectodomain shedding of the cell surface heparan sulphate proteoglycan syndecan-1 and elastin degradation in connective tissue. Here we present crystal structures of active LasA as a complex with tartrate and in the uncomplexed form. While the overall fold resembles that of the other M23 family members, the LasA active site is less constricted and utilizes a different set of metal ligands. The active site of uncomplexed LasA contains a five-coordinate zinc ion with trigonal bipyramidal geometry and two metal-bound water molecules. Using these structures as a starting point, we propose a model for substrate binding by LasA that explains its activity against a wider range of substrates than those used by related lytic enzymes, and offer a catalytic mechanism for M23 metallopeptidases consistent with available structural and mutagenesis data. Our results highlight how LasA is a structurally distinct member of this endopeptidase family, consistent with its activity against a wider range of substrates and with its multiple roles in Pseudomonas virulence.

  12. Rhoptry Proteins ROP5 and ROP18 Are Major Murine Virulence Factors in Genetically Divergent South American Strains of Toxoplasma gondii.

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    Michael S Behnke

    2015-08-01

    Full Text Available Toxoplasma gondii has evolved a number of strategies to evade immune responses in its many hosts. Previous genetic mapping of crosses between clonal type 1, 2, and 3 strains of T. gondii, which are prevalent in Europe and North America, identified two rhoptry proteins, ROP5 and ROP18, that function together to block innate immune mechanisms activated by interferon gamma (IFNg in murine hosts. However, the contribution of these and other virulence factors in more genetically divergent South American strains is unknown. Here we utilized a cross between the intermediately virulent North American type 2 ME49 strain and the highly virulent South American type 10 VAND strain to map the genetic basis for differences in virulence in the mouse. Quantitative trait locus (QTL analysis of this new cross identified one peak that spanned the ROP5 locus on chromosome XII. CRISPR-Cas9 mediated deletion of all copies of ROP5 in the VAND strain rendered it avirulent and complementation confirmed that ROP5 is the major virulence factor accounting for differences between type 2 and type 10 strains. To extend these observations to other virulent South American strains representing distinct genetic populations, we knocked out ROP5 in type 8 TgCtBr5 and type 4 TgCtBr18 strains, resulting in complete loss of virulence in both backgrounds. Consistent with this, polymorphisms that show strong signatures of positive selection in ROP5 were shown to correspond to regions known to interface with host immunity factors. Because ROP5 and ROP18 function together to resist innate immune mechanisms, and a significant interaction between them was identified in a two-locus scan, we also assessed the role of ROP18 in the virulence of South American strains. Deletion of ROP18 in South American type 4, 8, and 10 strains resulted in complete attenuation in contrast to a partial loss of virulence seen for ROP18 knockouts in previously described type 1 parasites. These data show that ROP5

  13. Antibiotic resistance, virulence factors and biofilm formation ability in Escherichia coli strains isolated from chicken meat and wildlife in the Czech Republic.

    Science.gov (United States)

    Pavlickova, Silvie; Klancnik, Anja; Dolezalova, Magda; Mozina, Sonja Smole; Holko, Ivan

    2017-08-03

    Attachment of pathogenic bacteria to food contact surfaces and the subsequent biofilm formation represent a serious threat for the food industry, since these bacteria are more resistant to antimicrobials or possess more virulence factors. The main aim of this study was to investigate the correlation between antibiotic resistance against 13 antibiotics, distribution of 10 virulence factors and biofilm formation in 105 Escherichia coli strains according to their origin. The high prevalence of antibiotic resistance that we have found in wildlife isolates could be acquired by horizontal transfer of resistance genes from human or domestic or farm animals. Consequently, these commensal bacteria might serve as indicator of antimicrobial usage for human and veterinary purposes in the Czech Republic. Further, 46 out of 66 resistant isolates (70%) were able to form biofilm and we found out statistically significant correlation between prevalence of antibiotic resistance and biofilm formation ability. The highest prevalence of antibiotic resistance was observed in weak biofilm producers. Biofilm formation was not statistically associated with any virulence determinant. However, we confirmed the correlation between prevalence of virulence factors and host origin. Chicken isolates possessed more virulence factors (66%), than isolates from wildlife (37%). We can conclude that the potential spread of antibiotic resistance pattern via the food chain is of high concern for public health. Even more, alarming is that E. coli isolates remain pathogenic potential with ability to form biofilm and these bacteria may persist during food processing and consequently lead to greater risks of food contamination.

  14. M-protein and other intrinsic virulence factors of Streptococcus pyogenes are encoded on an ancient pathogenicity island

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    Nakata Masanobu

    2009-04-01

    Full Text Available Abstract Background The increasing number of completely sequenced bacterial genomes allows comparing their architecture and genetic makeup. Such new information highlights the crucial role of lateral genetic exchanges in bacterial evolution and speciation. Results Here we analyzed the twelve sequenced genomes of Streptococcus pyogenes by a naïve approach that examines the preferential nucleotide usage along the chromosome, namely the usage of G versus C (GC-skew and T versus A (TA-skew. The cumulative GC-skew plot presented an inverted V-shape composed of two symmetrical linear segments, where the minimum and maximum corresponded to the origin and terminus of DNA replication. In contrast, the cumulative TA-skew presented a V-shape, which segments were interrupted by several steep slopes regions (SSRs, indicative of a different nucleotide composition bias. Each S. pyogenes genome contained up to nine individual SSRs, encompassing all described strain-specific prophages. In addition, each genome contained a similar unique non-phage SSR, the core of which consisted of 31 highly homologous genes. This core includes the M-protein, other mga-related factors and other virulence genes, totaling ten intrinsic virulence genes. In addition to a high content in virulence-related genes and to a peculiar nucleotide bias, this SSR, which is 47 kb-long in a M1GAS strain, harbors direct repeats and a tRNA gene, suggesting a mobile element. Moreover, its complete absence in a M-protein negative group A Streptococcus natural isolate demonstrates that it could be spontaneously lost, but in vitro deletion experiments indicates that its excision occurred at very low rate. The stability of this SSR, combined to its presence in all sequenced S. pyogenes sequenced genome, suggests that it results from an ancient acquisition. Conclusion Thus, this non-phagic SSR is compatible with a pathogenicity island, acquired before S. pyogenes speciation. Its potential excision

  15. Biogenesis of nanoparticles: A review

    African Journals Online (AJOL)

    SAM

    2014-07-09

    Jul 9, 2014 ... chemical routes known to use toxic chemicals for synthesis of nanoparticles but the need of the hour is to use environmental ... Key words: Biogenesis, nanofactories, nanoparticles, antimicrobial activity, semiconductor nanoparticles. ..... carbon composite materials for optically functional thin-film coatings.

  16. Purification, crystallization and preliminary X-ray diffraction analysis of Cif, a virulence factor secreted by Pseudomonas aeruginosa.

    Science.gov (United States)

    Bahl, Christopher D; MacEachran, Daniel P; O'Toole, George A; Madden, Dean R

    2010-01-01

    The opportunistic pathogen Pseudomonas aeruginosa secretes a protein that triggers the accelerated degradation of the cystic fibrosis transmembrane conductance regulator (CFTR) in airway epithelial cells. This protein, which is known as the CFTR inhibitory factor (Cif), acts as a virulence factor and may facilitate airway colonization by P. aeruginosa. Based on sequence similarity Cif appears to be an epoxide hydrolase (EH), but it lacks several of the conserved features found in the active sites of canonical members of the EH family. Here, the crystallization of purified recombinant Cif by vapor diffusion is reported. The crystals formed in space group C2, with unit-cell parameters a = 167.4, b = 83.6, c = 88.3 A, beta = 100.6 degrees . The crystals diffracted to 2.39 A resolution on a rotating-anode source. Based on the calculated Matthews coefficient (2.2 A(3) Da(-1)), it appears that the asymmetric unit contains four molecules.

  17. A mycobacterium ESX-1-secreted virulence factor with unique requirements for export.

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    Bryant McLaughlin

    2007-08-01

    Full Text Available Specialized secretion systems of pathogenic bacteria commonly transport multiple effectors that act in concert to control and exploit the host cell as a replication-permissive niche. Both the Mycobacterium marinum and the Mycobacterium tuberculosis genomes contain an extended region of difference 1 (extRD1 locus that encodes one such pathway, the early secretory antigenic target 6 (ESAT-6 system 1 (ESX-1 secretion apparatus. ESX-1 is required for virulence and for secretion of the proteins ESAT-6, culture filtrate protein 10 (CFP-10, and EspA. Here, we show that both Rv3881c and its M. marinum homolog, Mh3881c, are secreted proteins, and disruption of RD1 in either organism blocks secretion. We have renamed the Rv3881c/Mh3881c gene espB for ESX-1 substrate protein B. Secretion of M. marinum EspB (EspBM requires both the Mh3879c and Mh3871 genes within RD1, while CFP-10 secretion is not affected by disruption of Mh3879c. In contrast, disruption of Mh3866 or Mh3867 within the extRD1 locus prevents CFP-10 secretion without effect on EspBM. Mutants that fail to secrete only EspBM or only CFP-10 are less attenuated in macrophages than mutants failing to secrete both substrates. EspBM physically interacts with Mh3879c; the M. tuberculosis homolog, EspBT, physically interacts with Rv3879c; and mutants of EspBM that fail to bind Mh3879c fail to be secreted. We also found interaction between Rv3879c and Rv3871, a component of the ESX-1 machine, suggesting a mechanism for the secretion of EspB. The results establish EspB as a substrate of ESX-1 that is required for virulence and growth in macrophages and suggests that the contribution of ESX-1 to virulence may arise from the secretion of multiple independent substrates.

  18. Helicase-like transcription factor (Hltf regulates G2/M transition, Wt1/Gata4/Hif-1a cardiac transcription networks, and collagen biogenesis.

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    Rebecca A Helmer

    Full Text Available HLTF/Hltf regulates transcription, remodels chromatin, and coordinates DNA damage repair. Hltf is expressed in mouse brain and heart during embryonic and postnatal development. Silencing Hltf is semilethal. Seventy-four percent of congenic C57BL/6J Hltf knockout mice died, 75% within 12-24 hours of birth. Previous studies in neonatal (6-8 hour postpartum brain revealed silencing Hltf disrupted cell cycle progression, and attenuated DNA damage repair. An RNA-Seq snapshot of neonatal heart transcriptome showed 1,536 of 20,000 total transcripts were altered (p < 0.05 - 10 up- and 1,526 downregulated. Pathway enrichment analysis with MetaCore™ showed Hltf's regulation of the G2/M transition (p=9.726E(-15 of the cell cycle in heart is nearly identical to its role in brain. In addition, Brca1 and 12 members of the Brca1 associated genome surveillance complex are also downregulated. Activation of caspase 3 coincides with transcriptional repression of Bcl-2. Hltf loss caused downregulation of Wt1/Gata4/Hif-1a signaling cascades as well as Myh7b/miR499 transcription. Hltf-specific binding to promoters and/or regulatory regions of these genes was authenticated by ChIP-PCR. Hif-1a targets for prolyl (P4ha1, P4ha2 and lysyl (Plod2 collagen hydroxylation, PPIase enzymes (Ppid, Ppif, Ppil3 for collagen trimerization, and lysyl oxidase (Loxl2 for collagen-elastin crosslinking were downregulated. However, transcription of genes for collagens, fibronectin, Mmps and their inhibitors (Timps was unaffected. The collective downregulation of genes whose protein products control collagen biogenesis caused disorganization of the interstitial and perivascular myocardial collagen fibrillar network as viewed with picrosirius red-staining, and authenticated with spectral imaging. Wavy collagen bundles in control hearts contrasted with collagen fibers that were thin, short and disorganized in Hltf null hearts. Collagen bundles in Hltf null hearts were tangled and

  19. Acquisition and loss of virulence-associated factors during genome evolution and speciation in three clades of Bordetella species.

    Science.gov (United States)

    Linz, Bodo; Ivanov, Yury V; Preston, Andrew; Brinkac, Lauren; Parkhill, Julian; Kim, Maria; Harris, Simon R; Goodfield, Laura L; Fry, Norman K; Gorringe, Andrew R; Nicholson, Tracy L; Register, Karen B; Losada, Liliana; Harvill, Eric T

    2016-09-30

    The genus Bordetella consists of nine species that include important respiratory pathogens such as the 'classical' species B. bronchiseptica, B. pertussis and B. parapertussis and six more distantly related and less extensively studied species. Here we analyze sequence diversity and gene content of 128 genome sequences from all nine species with focus on the evolution of virulence-associated factors. Both genome-wide sequence-based and gene content-based phylogenetic trees divide the genus into three species clades. The phylogenies are congruent between species suggesting genus-wide co-evolution of sequence diversity and gene content, but less correlated within species, mainly because of strain-specific presence of many different prophages. We compared the genomes with focus on virulence-associated genes and identified multiple clade-specific, species-specific and strain-specific events of gene acquisition and gene loss, including genes encoding O-antigens, protein secretion systems and bacterial toxins. Gene loss was more frequent than gene gain throughout the evolution, and loss of hundreds of genes was associated with the origin of several species, including the recently evolved human-restricted B. pertussis and B. holmesii, B. parapertussis and the avian pathogen B. avium. Acquisition and loss of multiple genes drive the evolution and speciation in the genus Bordetella, including large scale gene loss associated with the origin of several species. Recent loss and functional inactivation of genes, including those encoding pertussis vaccine components and bacterial toxins, in individual strains emphasize ongoing evolution.

  20. Candida species from oral cavity of HIV-infected children exhibit reduced virulence factors in the HAART era.

    Science.gov (United States)

    Portela, Maristela Barbosa; Lima de Amorim, Elaine; Santos, Adrielle Mangabeira; Alexandre da Rocha Curvelo, José; de Oliveira Martins, Karol; Capillé, Cauli Lima; Maria de Araújo Soares, Rosangela; Barbosa de Araújo Castro, Gloria Fernanda

    2017-01-01

    This study aimed to assess, in vitro, the biofilm viability and the phospholipase and protease production of Candida spp. from the saliva of HIV infected children and healthy controls, and to correlate the results with the use of medical data. A total of 79 isolates were analyzed: 48 Candida albicans isolates (33/15) and 20 Candida parapsilosis sensu lato complex isolates (12/8) (from HIV/control patients, respectively), and 8 Candida krusei, 1 Candida tropicalis, 1 Candida dubliniensis and 1 Candida guilliermondii from HIV patients. The XTT (2, 3-bis (2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-Carboxanilide) reduction assay analyzed the biofilm viability. Phospholipase and protease assays were performed using the egg yolk and Bovine Serum Albumin agar plate methods, respectively. All isolates were able to form biofilm with cell viability. Quantitatively, Candida isolates from both groups presented a similar ability to form biofilm (p > 0.05). The biofilm viability activity was higher in C. albicans isolates than in non-albicans Candida isolates (p Candida spp. isolates from HIV-positive children presented higher phospholipase production, in vitro they exhibited reduced virulence factors compared to isolates from healthy individuals. This finding may enlighten the role played by immunosuppression in the modulation of Candida virulence attributes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Characterization of ApB73, a virulence factor important for colonization of Zea mays by the smut Ustilago maydis.

    Science.gov (United States)

    Stirnberg, Alexandra; Djamei, Armin

    2016-12-01

    The biotrophic fungus Ustilago maydis, the causal agent of corn smut disease, uses numerous small secreted effector proteins to suppress plant defence responses and reshape the host metabolism. However, the role of specific effectors remains poorly understood. Here, we describe the identification of ApB73 (Apathogenic in B73), an as yet uncharacterized protein essential for the successful colonization of maize by U. maydis. We show that apB73 is transcriptionally induced during the biotrophic stages of the fungal life cycle. The deletion of the apB73 gene results in cultivar-specific loss of gall formation in the host. The ApB73 protein is conserved among closely related smut fungi. However, using virulence assays, we show that only the orthologue of the maize-infecting head smut Sporisorium reilianum can complement the mutant phenotype of U. maydis. Although microscopy shows that ApB73 is secreted into the biotrophic interface, it seems to remain associated with fungal cell wall components or the fungal plasma membrane. Taken together, the results show that ApB73 is a conserved and important virulence factor of U. maydis that localizes to the interface between the pathogen and its host Zea mays. © 2016 THE AUTHORS. MOLECULAR PLANT PATHOLOGY PUBLISHED BY BRITISH SOCIETY FOR PLANT PATHOLOGY AND JOHN WILEY & SONS LTD.

  2. Prevalence of putative virulence factors and antimicrobial susceptibility of Enterococcus faecalis isolates from patients with dental Diseases

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    Abu Hammad Osama

    2008-06-01

    Full Text Available Abstract Background This study investigated the prevalence of Enterococcus faecalis, its putative virulence factors and antimicrobial susceptibility in individuals with and without dental diseases. A total of 159 oral rinse specimens were collected from patients (n = 109 suffering from dental diseases and healthy controls (n = 50. Results E. faecalis was detected using only culture in 8/109 (7.3% of the patients with various types of dental diseases, whereas no E. faecalis was found in the healthy controls weather using both culture and PCR. Phenotype characterizations of the 8 E. faecalis isolates indicated that 25% of the isolates produced haemolysin and 37.5% produced gelatinase. Most important virulence genes; collagen binding protein (ace and endocarditis antigen (efaA were present in all 8 E. faecalis isolates, while haemolysin activator gene (cylA was detected only in 25% of isolates, and all isolates were negative for esp gene. All E. faecalis isolates were 100% susceptible to ampicillin, chloramphenicol, ciprofloxacin, vancomycin, and teicoplanin, and to less extent to erythromycin (62.5%. Conclusion This study shows that all E. faecalis isolates were recovered only from patients with dental diseases especially necrotic pulps, and all isolates carried both collagen binding protein and endocarditis antigen genes and highly susceptible to frequently used antimicrobial drugs in Jordan.

  3. Discovery of Novel Secreted Virulence Factors from Salmonella enterica Serovar Typhimurium by Proteomic Analysis of Culture Supernatants

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    Niemann, George; Brown, Roslyn N.; Gustin, Jean K.; Stufkens, Afke; Shaikh-Kidwai, Afshan S.; Li, Jie; McDermott, Jason E.; Brewer, Heather M.; Schepmoes, Athena A.; Smith, Richard D.; Adkins, Joshua N.; Heffron, Fred

    2011-01-01

    The intracellular pathogen Salmonella enterica serovar Typhimurium is a leading cause of acute gastroenteritis in the world. This pathogen has two type-III secretion systems (TTSS) necessary for virulence that are encoded in Salmonella pathogenicity islands 1 and 2 (SPI-1 and SPI-2) and are expressed during extracellular or intracellular infectious states, respectively, to deliver virulence factors (effectors) to the host cell cytoplasm. While many have been identified and at least partially characterized, the full repertoire of effectors has not been catalogued. In this mass spectrometry-based proteomics study, we identified effector proteins secreted under minimal acidic medium growth conditions that induced the SPI-2 TTSS and its effectors, and compared the secretome from the parent strain to the secretome from strains missing either essential (SsaK) or regulatory components (SsaL) of the SPI-2 secretion apparatus. We identified 75% of the known TTSS effector repertoire. Excluding translocon components, 95% of the known effectors were biased for identification in the ssaL mutant background, which demonstrated that SsaL regulates SPI-2 type III secretion. To confirm secretion to animal cells, we made translational fusions of several of the best candidates to the calmodulin-dependent adenylate cyclase of Bordetella pertussis and assayed cAMP levels of infected J774 macrophage-like cells. From these infected cells we identified six new TTSS effectors and two others that are secreted independent of TTSS. Our results substantiate reports of additional secretion systems encoded by Salmonella other than TTSS.

  4. Functions of Burkholderia virulence factors: Input from proteomics and DNA microarray analyses

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    Kumutha Malar Vellasamy1

    2012-03-01

    Full Text Available Burkholderia spp. consists of organisms that are extremely diverse and versatile with a natural habitat in the soil. Members of this genus, which include B. pseudomallei, B. mallei, B. thailandensis and B. cepacia, are capable of causing severe, life threatening opportunistic infection in patients who are immunocompromised. The underlying virulence mechanisms of the bacteria, their interactions with the host and the host defense mechanisms may be reflected by changes of the expression of proteins of both the pathogen as well as the host. In this article, we reviewed the current knowledge on interactions of Burkholderia spp. pathogens with their host mainly from the perspective of data that was generated from recent proteomics and DNA microarray investigations.

  5. Expressed sequence tags from the oomycete fish pathogen Saprolegnia parasitica reveal putative virulence factors

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    van West Pieter

    2005-08-01

    Full Text Available Abstract Background The oomycete Saprolegnia parasitica is one of the most economically important fish pathogens. There is a dramatic recrudescence of Saprolegnia infections in aquaculture since the use of the toxic organic dye malachite green was banned in 2002. Little is known about the molecular mechanisms underlying pathogenicity in S. parasitica and other animal pathogenic oomycetes. In this study we used a genomics approach to gain a first insight into the transcriptome of S. parasitica. Results We generated 1510 expressed sequence tags (ESTs from a mycelial cDNA library of S. parasitica. A total of 1279 consensus sequences corresponding to 525944 base pairs were assembled. About half of the unigenes showed similarities to known protein sequences or motifs. The S. parasitica sequences tended to be relatively divergent from Phytophthora sequences. Based on the sequence alignments of 18 conserved proteins, the average amino acid identity between S. parasitica and three Phytophthora species was 77% compared to 93% within Phytophthora. Several S. parasitica cDNAs, such as those with similarity to fungal type I cellulose binding domain proteins, PAN/Apple module proteins, glycosyl hydrolases, proteases, as well as serine and cysteine protease inhibitors, were predicted to encode secreted proteins that could function in virulence. Some of these cDNAs were more similar to fungal proteins than to other eukaryotic proteins confirming that oomycetes and fungi share some virulence components despite their evolutionary distance Conclusion We provide a first glimpse into the gene content of S. parasitica, a reemerging oomycete fish pathogen. These resources will greatly accelerate research on this important pathogen. The data is available online through the Oomycete Genomics Database 1.

  6. Comparative Transcriptome Analysis Reveals Cool Virulence Factors of Ralstonia solanacearum Race 3 Biovar 2.

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    Fanhong Meng

    Full Text Available While most strains of the plant pathogenic bacterium Ralstonia solanacearum are tropical, the race 3 biovar 2 (R3bv2 subgroup attacks plants in cooler climates. To identify mechanisms underlying this trait, we compared the transcriptional profiles of R. solanacearum R3bv2 strain UW551 and tropical strain GMI1000 at 20°C and 28°C, both in culture and during tomato pathogenesis. 4.2% of the ORFs in the UW551 genome and 7.9% of the GMI1000 ORFs were differentially expressed by temperature in planta. The two strains had distinct transcriptional responses to temperature change. GMI1000 up-regulated several stress response genes at 20°C, apparently struggling to cope with plant defenses. At the cooler temperature, R3bv2 strain UW551 up-regulated a cluster encoding a mannose-fucose binding lectin, LecM; a quorum sensing-dependent protein, AidA; and a related hypothetical protein, AidC. The last two genes are absent from the GMI1000 genome. In UW551, all three genes were positively regulated by the adjacent SolI/R quorum sensing system. These temperature-responsive genes were required for full virulence in R3bv2. Mutants lacking lecM, aidA, or aidC were each significantly more reduced in virulence on tomato at 20°C than at 28°C in both a naturalistic soil soak inoculation assay and when they were inoculated directly into tomato stems. The lecM and aidC mutants also survived poorly in potato tubers at the seed tuber storage temperature of 4°C, and the lecM mutant was defective in biofilm formation in vitro. Together, these results suggest novel mechanisms, including a lectin, are involved in the unique temperate epidemiology of R3bv2.

  7. Pyocyanina contributory factor in haem acquisition and virulence enhancement of Porphyromonas gingivalis in the lung [corrected].

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    Malgorzata Benedyk

    Full Text Available Several recent studies show that the lungs infected with Pseudomonas aeruginosa are often co-colonised by oral bacteria including black-pigmenting anaerobic (BPA Porphyromonas species. The BPAs have an absolute haem requirement and their presence in the infected lung indicates that sufficient haem, a virulence up-regulator in BPAs, must be present to support growth. Haemoglobin from micro-bleeds occurring during infection is the most likely source of haem in the lung. Porphyromonas gingivalis displays a novel haem acquisition paradigm whereby haemoglobin must be firstly oxidised to methaemoglobin, facilitating haem release, either by gingipain proteolysis or capture via the haem-binding haemophore HmuY. P. aeruginosa produces the blue phenazine redox compound, pyocyanin. Since phenazines can oxidise haemoglobin, it follows that pyocyanin may also facilitate haem acquisition by promoting methaemoglobin production. Here we show that pyocyanin at concentrations found in the CF lung during P. aeruginosa infections rapidly oxidises oxyhaemoglobin in a dose-dependent manner. We demonstrate that methaemoglobin formed by pyocyanin is also susceptible to proteolysis by P. gingivalis Kgp gingipain and neutrophil elastase, thus releasing haem. Importantly, co-incubation of oxyhaemoglobin with pyocyanin facilitates haem pickup from the resulting methemoglobin by the P. gingivalis HmuY haemophore. Mice intra-tracheally challenged with viable P. gingivalis cells plus pyocyanin displayed increased mortality compared to those administered P. gingivalis alone. Pyocyanin significantly elevated both methaemoglobin and total haem levels in homogenates of mouse lungs and increased the level of arginine-specific gingipain activity from mice inoculated with viable P. gingivalis cells plus pyocyanin compared with mice inoculated with P. gingivalis only. These findings indicate that pyocyanin, by promoting haem availability through methaemoglobin formation and

  8. Pyocyanina contributory factor in haem acquisition and virulence enhancement of Porphyromonas gingivalis in the lung [corrected].

    Science.gov (United States)

    Benedyk, Malgorzata; Byrne, Dominic P; Glowczyk, Izabela; Potempa, Jan; Olczak, Mariusz; Olczak, Teresa; Smalley, John W

    2015-01-01

    Several recent studies show that the lungs infected with Pseudomonas aeruginosa are often co-colonised by oral bacteria including black-pigmenting anaerobic (BPA) Porphyromonas species. The BPAs have an absolute haem requirement and their presence in the infected lung indicates that sufficient haem, a virulence up-regulator in BPAs, must be present to support growth. Haemoglobin from micro-bleeds occurring during infection is the most likely source of haem in the lung. Porphyromonas gingivalis displays a novel haem acquisition paradigm whereby haemoglobin must be firstly oxidised to methaemoglobin, facilitating haem release, either by gingipain proteolysis or capture via the haem-binding haemophore HmuY. P. aeruginosa produces the blue phenazine redox compound, pyocyanin. Since phenazines can oxidise haemoglobin, it follows that pyocyanin may also facilitate haem acquisition by promoting methaemoglobin production. Here we show that pyocyanin at concentrations found in the CF lung during P. aeruginosa infections rapidly oxidises oxyhaemoglobin in a dose-dependent manner. We demonstrate that methaemoglobin formed by pyocyanin is also susceptible to proteolysis by P. gingivalis Kgp gingipain and neutrophil elastase, thus releasing haem. Importantly, co-incubation of oxyhaemoglobin with pyocyanin facilitates haem pickup from the resulting methemoglobin by the P. gingivalis HmuY haemophore. Mice intra-tracheally challenged with viable P. gingivalis cells plus pyocyanin displayed increased mortality compared to those administered P. gingivalis alone. Pyocyanin significantly elevated both methaemoglobin and total haem levels in homogenates of mouse lungs and increased the level of arginine-specific gingipain activity from mice inoculated with viable P. gingivalis cells plus pyocyanin compared with mice inoculated with P. gingivalis only. These findings indicate that pyocyanin, by promoting haem availability through methaemoglobin formation and stimulating of gingipain

  9. Pyocycanin, a Contributory Factor in Haem Acquisition and Virulence Enhancement of Porphyromonas gingivalis in the Lung

    Science.gov (United States)

    Benedyk, Malgorzata; Byrne, Dominic P.; Glowczyk, Izabela; Potempa, Jan; Olczak, Mariusz; Olczak, Teresa; Smalley, John W.

    2015-01-01

    Several recent studies show that the lungs infected with Pseudomonas aeruginosa are often co-colonised by oral bacteria including black-pigmenting anaerobic (BPA) Porphyromonas species. The BPAs have an absolute haem requirement and their presence in the infected lung indicates that sufficient haem, a virulence up-regulator in BPAs, must be present to support growth. Haemoglobin from micro-bleeds occurring during infection is the most likely source of haem in the lung. Porphyromonas gingivalis displays a novel haem acquisition paradigm whereby haemoglobin must be firstly oxidised to methaemoglobin, facilitating haem release, either by gingipain proteolysis or capture via the haem-binding haemophore HmuY. P. aeruginosa produces the blue phenazine redox compound, pyocyanin. Since phenazines can oxidise haemoglobin, it follows that pyocyanin may also facilitate haem acquisition by promoting methaemoglobin production. Here we show that pyocyanin at concentrations found in the CF lung during P. aeruginosa infections rapidly oxidises oxyhaemoglobin in a dose-dependent manner. We demonstrate that methaemoglobin formed by pyocyanin is also susceptible to proteolysis by P. gingivalis Kgp gingipain and neutrophil elastase, thus releasing haem. Importantly, co-incubation of oxyhaemoglobin with pyocyanin facilitates haem pickup from the resulting methemoglobin by the P. gingivalis HmuY haemophore. Mice intra-tracheally challenged with viable P. gingivalis cells plus pyocyanin displayed increased mortality compared to those administered P. gingivalis alone. Pyocyanin significantly elevated both methaemoglobin and total haem levels in homogenates of mouse lungs and increased the level of arginine-specific gingipain activity from mice inoculated with viable P. gingivalis cells plus pyocyanin compared with mice inoculated with P. gingivalis only. These findings indicate that pyocyanin, by promoting haem availability through methaemoglobin formation and stimulating of gingipain

  10. Biofilm formation and virulence factor analysis of Staphylococcus aureus isolates collected from ovine mastitis.

    Science.gov (United States)

    Azara, E; Longheu, C; Sanna, G; Tola, S

    2017-08-01

    To perform a phenotypic and genotypic characterization of 258 Staphylococcus aureus isolates from clinical ovine mastitis and used for the preparation of inactivated autogenous vaccines. The potential for biofilm production was determined by phenotypic test of Congo Red Agar (CRA) and by PCR for the detection of icaA/D genes. Isolates were also screened by PCR for the presence of enterotoxins (sea, seb, sec, sed and see), toxic shock syndrome toxin (tsst), leukotoxins (lukD-E, lukM and lukPV83), haemolysins (hly-β and hly-γ), autolysin (atlA) genes and encoding microbial surface components recognizing adhesive matrix molecules (MSCRAMMs: clfA, clfB, fnbA, fnbB, bbp, cna, eno, fib, epbs, sdrC, sdrD and SdrE). None of the 258 isolates showed biofilm-forming ability on CRA and harboured icaA/D genes. The most frequent pyrogenic toxin superantigen genes amplified were sec plus tsst-1, which were found strictly in combination with 71·3% of the Staph. aureus isolates tested. None of the isolates harboured the genes encoding sea and see. Of the 258 isolates tested, 159 (61·6%) possessed all lukD-E/lukM/lukPV83 genes, 123 (47·7%) harboured both hly-β/hly-γ genes, whereas almost all (97·3%) were PCR positive for atlA gene. With respect to adhesion determinants, 179 (69·4%) isolates presented simultaneously four genes (fnbA, fib, clfA and clfB) for fibronectin- and fibrinogen-binding proteins. In this search, several putative virulence determinants have been identified in ovine Staph. aureus isolates collected in Sardinia. Some of the putative virulence determinants could be considered as components of a vaccine because of their role in ovine mastitis pathogenesis. © 2017 The Society for Applied Microbiology.

  11. Plasmodium falciparum heterochromatin protein 1 marks genomic loci linked to phenotypic variation of exported virulence factors.

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    Christian Flueck

    2009-09-01

    Full Text Available Epigenetic processes are the main conductors of phenotypic variation in eukaryotes. The malaria parasite Plasmodium falciparum employs antigenic variation of the major surface antigen PfEMP1, encoded by 60 var genes, to evade acquired immune responses. Antigenic variation of PfEMP1 occurs through in situ switches in mono-allelic var gene transcription, which is PfSIR2-dependent and associated with the presence of repressive H3K9me3 marks at silenced loci. Here, we show that P. falciparum heterochromatin protein 1 (PfHP1 binds specifically to H3K9me3 but not to other repressive histone methyl marks. Based on nuclear fractionation and detailed immuno-localization assays, PfHP1 constitutes a major component of heterochromatin in perinuclear chromosome end clusters. High-resolution genome-wide chromatin immuno-precipitation demonstrates the striking association of PfHP1 with virulence gene arrays in subtelomeric and chromosome-internal islands and a high correlation with previously mapped H3K9me3 marks. These include not only var genes, but also the majority of P. falciparum lineage-specific gene families coding for exported proteins involved in host-parasite interactions. In addition, we identified a number of PfHP1-bound genes that were not enriched in H3K9me3, many of which code for proteins expressed during invasion or at different life cycle stages. Interestingly, PfHP1 is absent from centromeric regions, implying important differences in centromere biology between P. falciparum and its human host. Over-expression of PfHP1 results in an enhancement of variegated expression and highlights the presence of well-defined heterochromatic boundaries. In summary, we identify PfHP1 as a major effector of virulence gene silencing and phenotypic variation. Our results are instrumental for our understanding of this widely used survival strategy in unicellular pathogens.

  12. The secreted autotransporter toxin (Sat) does not act as a virulence factor in the probiotic Escherichia coli strain Nissle 1917.

    Science.gov (United States)

    Toloza, Lorena; Giménez, Rosa; Fábrega, María Jose; Alvarez, Carina Shianya; Aguilera, Laura; Cañas, María Alexandra; Martín-Venegas, Raquel; Badia, Josefa; Baldomà, Laura

    2015-10-30

    Escherichia coli Nissle 1917 (EcN) is a probiotic used in the treatment of intestinal diseases. Although it is considered safe, EcN is closely related to the uropathogenic E. coli strain CFT073 and contains many of its predicted virulence elements. Thus, it is relevant to assess whether virulence-associated genes are functional in EcN. One of these genes encodes the secreted autotransporter toxin (Sat), a member of the serine protease autotransporters of Enterobacteriaceae (SPATEs) that are secreted following the type V autotransporter pathway. Sat is highly prevalent in certain E. coli pathogenic groups responsible for urinary and intestinal infections. In these pathogens Sat promotes cytotoxic effects in several lines of undifferentiated epithelial cells, but not in differentiated Caco-2 cells. Here we provide evidence that sat is expressed by EcN during the colonization of mouse intestine. The EcN protein is secreted as an active serine protease, with its 107 kDa-passenger domain released into the medium as a soluble protein. Expression of recombinant EcN Sat protein in strain HB101 increases paracellular permeability to mannitol in polarized Caco-2 monolayers. This effect, also reported for the Sat protein of diffusely adherent E. coli, is not observed when this protein is expressed in the EcN background. In addition, we show that EcN supernatants confer protection against Sat-mediated effects on paracellular permeability, thus indicating that other secreted EcN factors are able to prevent barrier disruption caused by pathogen-related factors. Sat is not required for intestinal colonization, but the EcNsat::cat mutant outcompetes wild-type EcN in the streptomycin-treated mouse model. Analysis of the presence of sat in 29 strains of the ECOR collection isolated from stools of healthy humans shows 34.8 % positives, with high prevalence of strains of the phylogenetic groups D and B2, related with extra-intestinal infections. Sat does not act as a virulence factor

  13. Biochemical characteristics, serogroups, and virulence factors of aeromonas species isolated from cases of diarrhoea and domestic water samples in Chennai

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    Alavandi S

    2003-01-01

    Full Text Available PURPOSE: The objective of the present study was to delineate the differences between the clinical and environmental Aeromonas species with respect to their biochemical characteristics, serogrouping and virulence factors, in order to find a phenotypic marker of enteropathogenicity. METHODS: A total of 55 Aeromonas spp. inclusive of 19 isolates from cases of diarrhoea, and 36 from water samples comprising, 10 isolates of A. hydrophila, 21 isolates each of A. sobria, and A. caviae, two isolates of A. jandaei and one isolate of A. veronii were subjected to analysis of their biochemical characteristics, serogrouping, and virulence factors. RESULTS: Among the differences recorded in the biochemical characteristics in the three major species, the most striking characteristic was fermentation of lactose, which was observed in all the 11 A. caviae isolates recovered from water samples. None of the 10 clinical isolates of A. caviae tested fermented lactose. The clinical Aeromonas isolates belonged to seven typable serogroups, O:13, O:14, O:16, O:21, O:27, O:32 and O:35. The environmental isolates belonged to eight different serogroups, such as, O:3, O:11, O:14, O:16, O:18, O:28, O:64 and O:78 and were predominated by serotypes O:18 and O:64. Among the virulence factors tested, 89% of the environmental isolates produced b haemolysin, while only 62.3% of clinical isolates were able to do so. There was no significant difference between the clinical and environmental aeromonads with respect to their enterotoxigenicity in suckling mice in vivo, cytotoxicity in vitro in Vero cell monolayers, and ability to produce siderophores. CONCLUSION: Efforts to delineate the differences between the clinical and environmental Aeromonas spp. did not reveal significant difference between them. However, difference was observed with respect to their ability to produce b haemolysin, wherein, higher percentage of environmental isolates was haemolytic. The results also suggest

  14. Modulation of Host Immunity by Human Respiratory Syncytial Virus Virulence Factors: A Synergic Inhibition of Both Innate and Adaptive Immunity

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    Gisela Canedo-Marroquín

    2017-08-01

    Full Text Available The Human Respiratory Syncytial Virus (hRSV is a major cause of acute lower respiratory tract infections (ARTIs and high rates of hospitalizations in children and in the elderly worldwide. Symptoms of hRSV infection include bronchiolitis and pneumonia. The lung pathology observed during hRSV infection is due in part to an exacerbated host immune response, characterized by immune cell infiltration to the lungs. HRSV is an enveloped virus, a member of the Pneumoviridae family, with a non-segmented genome and negative polarity-single RNA that contains 10 genes encoding for 11 proteins. These include the Fusion protein (F, the Glycoprotein (G, and the Small Hydrophobic (SH protein, which are located on the virus surface. In addition, the Nucleoprotein (N, Phosphoprotein (P large polymerase protein (L part of the RNA-dependent RNA polymerase complex, the M2-1 protein as a transcription elongation factor, the M2-2 protein as a regulator of viral transcription and (M protein all of which locate inside the virion. Apart from the structural proteins, the hRSV genome encodes for the non-structural 1 and 2 proteins (NS1 and NS2. HRSV has developed different strategies to evade the host immunity by means of the function of some of these proteins that work as virulence factors to improve the infection in the lung tissue. Also, hRSV NS-1 and NS-2 proteins have been shown to inhibit the activation of the type I interferon response. Furthermore, the hRSV nucleoprotein has been shown to inhibit the immunological synapsis between the dendritic cells and T cells during infection, resulting in an inefficient T cell activation. Here, we discuss the hRSV virulence factors and the host immunological features raised during infection with this virus.

  15. Assessment of food safety using a new real-time PCR assay for detection and quantification of virulence factors of enterococci in food samples.

    Science.gov (United States)

    Abouelnaga, M; Lamas, A; Guarddon, M; Osman, M; Miranda, J M; Cepeda, A; Franco, C M

    2016-12-01

    Development of Taqman MGB real-time PCR (q-PCR) assays for the quantitative detection of virulence factor genes in pure culture and food samples with regard to food safety assessment. New Taqman primers and probes were designed for the ace, esp and gelE genes based on the determinants of virulence profiles of enterococcal strains from GenBank. The high specificity and accuracy of the Taqman probe assay was confirmed. The limit of detection for the different virulence genes was 102  CFU ml-1 or CFU g-1 for pure culture and meat samples, and 103  CFU g-1 for cheese samples. This method provides the specific and rapid detection and quantification of ace, esp and gelE genes compared to conventional PCR assays, thus allowing the rapid and direct safety assessment of Enterococcus genus in food samples. This study presents efficient methods that can be used directly on food products for the rapid quantification and tracing of virulence genes, regarding food safety assessment. Moreover, this is the first study to quantify these virulence factors using a specific Taqman q-PCR assay in food samples. © 2016 The Society for Applied Microbiology.

  16. Occurrence of virulence factors and antimicrobial resistance in Pasteurella multocida strains isolated from slaughter cattle in Iran

    Science.gov (United States)

    Khamesipour, Faham; Momtaz, Hassan; Azhdary Mamoreh, Morteza

    2014-01-01

    A total of 30 Pasteurella multocida strains isolated from 333 pneumonic and apparently health slaughter cattle were examined for capsule biosynthesis genes and 23 virulence-associated genes by polymerase chain reaction (PCR). The disc diffusion technique was used to determine antimicrobial resistance profiles among the isolates. Of the isolates, 23 belonged to capsular type A, 5 to capsular type D and two isolates were untypeable. The distribution of the capsular types in pneumonic lungs and in apparently health lungs was statistically similar. All virulence genes tested were detected among the isolates derived from pneumonic lungs; whereas isolates derived from apparently health lungs carried 16 of the 23 genes. The frequently detected genes among isolates from pneumonic lungs were exbD, hgbA, hgbB, ompA, ompH, oma87, and sodC; whereas tadD, toxA, and pmHAS genes occurred less frequently. Most of the adhesins and superoxide dismutases; and all of the iron acquisition and protectin proteins occurred at significantly (p ≤ 0.05) higher frequencies in isolates from pneumonic lungs. Isolates from apparently healthy lungs didn't carry the following genes; hsf-1, hsf-2, tadD, toxA, nanB, nanH, and pmHAS. One adhesion (hsf-1) and two iron acquisition (exbD and tonB) genes occurred at significantly (p ≤ 0.05) higher frequencies among capA isolates. All the P. multocida isolates were susceptible to ciprofloxacin, co-trimoxazole, doxycycline, enrofloxacin, nitrofurantoin, and tetracyclines. Different proportions of the isolates were however resistant to ampicillin, amoxicillin, erythromycin, lincomycin, penicillin, rifampin, streptomycin, and florfenicol. Our results reveal presence of virulence factors (VFs) in P. multocida strains isolated from symptomatic and asymptomatic bovids. A higher frequency of the factors among isolates from symptomatic study animals may suggest their role in pathogenesis of P. multocida-associated bovine respiratory disease (BRD). The results

  17. Occurrence of virulence factors and antimicrobial resistance in Pasteurella multocida strains isolated from slaughter cattle in Iran.

    Science.gov (United States)

    Khamesipour, Faham; Momtaz, Hassan; Azhdary Mamoreh, Morteza

    2014-01-01

    A total of 30 Pasteurella multocida strains isolated from 333 pneumonic and apparently health slaughter cattle were examined for capsule biosynthesis genes and 23 virulence-associated genes by polymerase chain reaction (PCR). The disc diffusion technique was used to determine antimicrobial resistance profiles among the isolates. Of the isolates, 23 belonged to capsular type A, 5 to capsular type D and two isolates were untypeable. The distribution of the capsular types in pneumonic lungs and in apparently health lungs was statistically similar. All virulence genes tested were detected among the isolates derived from pneumonic lungs; whereas isolates derived from apparently health lungs carried 16 of the 23 genes. The frequently detected genes among isolates from pneumonic lungs were exbD, hgbA, hgbB, ompA, ompH, oma87, and sodC; whereas tadD, toxA, and pmHAS genes occurred less frequently. Most of the adhesins and superoxide dismutases; and all of the iron acquisition and protectin proteins occurred at significantly (p ≤ 0.05) higher frequencies in isolates from pneumonic lungs. Isolates from apparently healthy lungs didn't carry the following genes; hsf-1, hsf-2, tadD, toxA, nanB, nanH, and pmHAS. One adhesion (hsf-1) and two iron acquisition (exbD and tonB) genes occurred at significantly (p ≤ 0.05) higher frequencies among capA isolates. All the P. multocida isolates were susceptible to ciprofloxacin, co-trimoxazole, doxycycline, enrofloxacin, nitrofurantoin, and tetracyclines. Different proportions of the isolates were however resistant to ampicillin, amoxicillin, erythromycin, lincomycin, penicillin, rifampin, streptomycin, and florfenicol. Our results reveal presence of virulence factors (VFs) in P. multocida strains isolated from symptomatic and asymptomatic bovids. A higher frequency of the factors among isolates from symptomatic study animals may suggest their role in pathogenesis of P. multocida-associated bovine respiratory disease (BRD). The results

  18. Fis Is Essential for Capsule Production in Pasteurella multocida and Regulates Expression of Other Important Virulence Factors

    Science.gov (United States)

    Steen, Jason A.; Steen, Jennifer A.; Harrison, Paul; Seemann, Torsten; Wilkie, Ian; Harper, Marina; Adler, Ben; Boyce, John D.

    2010-01-01

    P. multocida is the causative agent of a wide range of diseases of animals, including fowl cholera in poultry and wild birds. Fowl cholera isolates of P. multocida generally express a capsular polysaccharide composed of hyaluronic acid. There have been reports of spontaneous capsule loss in P. multocida, but the mechanism by which this occurs has not been determined. In this study, we identified three independent strains that had spontaneously lost the ability to produce capsular polysaccharide. Quantitative RT-PCR showed that these strains had significantly reduced transcription of the capsule biosynthetic genes, but DNA sequence analysis identified no mutations within the capsule biosynthetic locus. However, whole-genome sequencing of paired capsulated and acapsular strains identified a single point mutation within the fis gene in the acapsular strain. Sequencing of fis from two independently derived spontaneous acapsular strains showed that each contained a mutation within fis. Complementation of these strains with an intact copy of fis, predicted to encode a transcriptional regulator, returned capsule expression to all strains. Therefore, expression of a functional Fis protein is essential for capsule expression in P. multocida. DNA microarray analysis of one of the spontaneous fis mutants identified approximately 30 genes as down-regulated in the mutant, including pfhB_2, which encodes a filamentous hemagglutinin, a known P. multocida virulence factor, and plpE, which encodes the cross protective surface antigen PlpE. Therefore these experiments define for the first time a mechanism for spontaneous capsule loss in P. multocida and identify Fis as a critical regulator of capsule expression. Furthermore, Fis is involved in the regulation of a range of other P. multocida genes including important virulence factors. PMID:20140235

  19. Fis is essential for capsule production in Pasteurella multocida and regulates expression of other important virulence factors.

    Directory of Open Access Journals (Sweden)

    Jason A Steen

    2010-02-01

    Full Text Available P. multocida is the causative agent of a wide range of diseases of animals, including fowl cholera in poultry and wild birds. Fowl cholera isolates of P. multocida generally express a capsular polysaccharide composed of hyaluronic acid. There have been reports of spontaneous capsule loss in P. multocida, but the mechanism by which this occurs has not been determined. In this study, we identified three independent strains that had spontaneously lost the ability to produce capsular polysaccharide. Quantitative RT-PCR showed that these strains had significantly reduced transcription of the capsule biosynthetic genes, but DNA sequence analysis identified no mutations within the capsule biosynthetic locus. However, whole-genome sequencing of paired capsulated and acapsular strains identified a single point mutation within the fis gene in the acapsular strain. Sequencing of fis from two independently derived spontaneous acapsular strains showed that each contained a mutation within fis. Complementation of these strains with an intact copy of fis, predicted to encode a transcriptional regulator, returned capsule expression to all strains. Therefore, expression of a functional Fis protein is essential for capsule expression in P. multocida. DNA microarray analysis of one of the spontaneous fis mutants identified approximately 30 genes as down-regulated in the mutant, including pfhB_2, which encodes a filamentous hemagglutinin, a known P. multocida virulence factor, and plpE, which encodes the cross protective surface antigen PlpE. Therefore these experiments define for the first time a mechanism for spontaneous capsule loss in P. multocida and identify Fis as a critical regulator of capsule expression. Furthermore, Fis is involved in the regulation of a range of other P. multocida genes including important virulence factors.

  20. Fis is essential for capsule production in Pasteurella multocida and regulates expression of other important virulence factors.

    Science.gov (United States)

    Steen, Jason A; Steen, Jennifer A; Harrison, Paul; Seemann, Torsten; Wilkie, Ian; Harper, Marina; Adler, Ben; Boyce, John D

    2010-02-05

    P. multocida is the causative agent of a wide range of diseases of animals, including fowl cholera in poultry and wild birds. Fowl cholera isolates of P. multocida generally express a capsular polysaccharide composed of hyaluronic acid. There have been reports of spontaneous capsule loss in P. multocida, but the mechanism by which this occurs has not been determined. In this study, we identified three independent strains that had spontaneously lost the ability to produce capsular polysaccharide. Quantitative RT-PCR showed that these strains had significantly reduced transcription of the capsule biosynthetic genes, but DNA sequence analysis identified no mutations within the capsule biosynthetic locus. However, whole-genome sequencing of paired capsulated and acapsular strains identified a single point mutation within the fis gene in the acapsular strain. Sequencing of fis from two independently derived spontaneous acapsular strains showed that each contained a mutation within fis. Complementation of these strains with an intact copy of fis, predicted to encode a transcriptional regulator, returned capsule expression to all strains. Therefore, expression of a functional Fis protein is essential for capsule expression in P. multocida. DNA microarray analysis of one of the spontaneous fis mutants identified approximately 30 genes as down-regulated in the mutant, including pfhB_2, which encodes a filamentous hemagglutinin, a known P. multocida virulence factor, and plpE, which encodes the cross protective surface antigen PlpE. Therefore these experiments define for the first time a mechanism for spontaneous capsule loss in P. multocida and identify Fis as a critical regulator of capsule expression. Furthermore, Fis is involved in the regulation of a range of other P. multocida genes including important virulence factors.

  1. Bacterial spot of tomato and pepper: diverse Xanthomonas species with a wide variety of virulence factors posing a worldwide challenge.

    Science.gov (United States)

    Potnis, Neha; Timilsina, Sujan; Strayer, Amanda; Shantharaj, Deepak; Barak, Jeri D; Paret, Mathews L; Vallad, Gary E; Jones, Jeffrey B

    2015-12-01

    Bacteria; Phylum Proteobacteria; Class Gammaproteobacteria; Order Xanthomonadales; Family Xanthomonadaceae; Genus Xanthomonas; Species Xanthomonas euvesicatoria, Xanthomonas vesicatoria, Xanthomonas perforans and Xanthomonas gardneri. Gram-negative, rod-shaped bacterium, aerobic, motile, single polar flagellum. Causes bacterial spot disease on plants belonging to the Solanaceae family, primarily tomato (Solanum lycopersicum), pepper (Capsicum annuum) and chilli peppers (Capsicum frutescens). Necrotic lesions on all above-ground plant parts. Worldwide distribution of X. euvesicatoria and X. vesicatoria on tomato and pepper; X. perforans and X. gardneri increasingly being isolated from the USA, Canada, South America, Africa and Europe. A wide diversity within the bacterial spot disease complex, with an ability to cause disease at different temperatures, makes this pathogen group a worldwide threat to tomato and pepper production. Recent advances in genome analyses have revealed the evolution of the pathogen with a plethora of novel virulence factors. Current management strategies rely on the use of various chemical control strategies and sanitary measures to minimize pathogen spread through contaminated seed. Chemical control strategies have been a challenge because of resistance by the pathogen. Breeding programmes have been successful in developing commercial lines with hypersensitive and quantitative resistance. However, durability of resistance has been elusive. Recently, a transgenic approach has resulted in the development of tomato genotypes with significant levels of resistance and improved yield that hold promise. In this article, we discuss the current taxonomic status, distribution of the four species, knowledge of virulence factors, detection methods and strategies for disease control with possible directions for future research. © 2015 BSPP AND JOHN WILEY & SONS LTD.

  2. Streptococcal 5'-Nucleotidase A (S5nA), a Novel Streptococcus pyogenes Virulence Factor That Facilitates Immune Evasion.

    Science.gov (United States)

    Zheng, Lisa; Khemlani, Adrina; Lorenz, Natalie; Loh, Jacelyn M S; Langley, Ries J; Proft, Thomas

    2015-12-25

    Streptococcus pyogenes is an important human pathogen that causes a wide range of diseases. Using bioinformatics analysis of the complete S. pyogenes strain SF370 genome, we have identified a novel S. pyogenes virulence factor, which we termed streptococcal 5'-nucleotidase A (S5nA). A recombinant form of S5nA hydrolyzed AMP and ADP, but not ATP, to generate the immunomodulatory molecule adenosine. Michaelis-Menten kinetics revealed a Km of 169 μm and a Vmax of 7550 nmol/mg/min for the substrate AMP. Furthermore, recombinant S5nA acted synergistically with S. pyogenes nuclease A to generate macrophage-toxic deoxyadenosine from DNA. The enzyme showed optimal activity between pH 5 and pH 6.5 and between 37 and 47 °C. Like other 5'-nucleotidases, S5nA requires divalent cations and was active in the presence of Mg(2+), Ca(2+), or Mn(2+). However, Zn(2+) inhibited the enzymatic activity. Structural modeling combined with mutational analysis revealed a highly conserved catalytic dyad as well as conserved substrate and cation-binding sites. Recombinant S5nA significantly increased the survival of the non-pathogenic bacterium Lactococcus lactis during a human whole blood killing assay in a dose-dependent manner, suggesting a role as an S. pyogenes virulence factor. In conclusion, we have identified a novel S. pyogenes enzyme with 5'-nucleotidase activity and immune evasion properties. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  3. Celulitis in Japanese Quails (coturnix coturnix japonica for Eschorichia coli: virulence factors, sensibility and profile antimicrobial resistance /Celulite em codornas (coturnix coturnix japonica causada por Escherichia coli: fatores de virulência, sensibilidade e perfil de resistência antimicrobiana

    Directory of Open Access Journals (Sweden)

    Marilda Carlos Vidotto

    2000-12-01

    Full Text Available Ten E. coli strains isolated from celulitis lesion s of Japanese quails were to evaluated antimicrobia l resistance to twent y six drugs , to pathogenicity of strains in SPF chickens embryonated eggs and virulence factors. The antimicrobials of higher efficiency wer e ampicillin, florfenicol and the lesser efficiency were erythromycin, oxacilin, lincomicin, novobiocin, penicillin, sulfonamidas, trimethoprim+sulfomethoxazo/e and tetracyicline. The majority of E. coli strains were serum resistance, the others virulence factors, hemolisin and congo red affinity, were lesser frequent on the studied strains. Pathogenicity of E. coli strains, evaluated to DL50 in embryonated eggs, had varied of 8x10 2 the 3,2x10.Dez cepas de E. coli isoladas de lesões de celulite em codornas foram avaliadas quanto a resistência antimicrobiana frente a vinte e seis drogas, a patogenicidade das amostras em ovos embrionários de galinha SPF e quanto aos fatores de virulência: hemolisinas, resistência sérica e afinidade ao vermelho congo Os antimicrobianos de maior eficiência foram ampicilinar florfenicol e os menos eficientes foram eritromicina, oxacilina. lincomicina, novobiocina. penicsilna, sulfonamida, sulfomethoxazole+ trimetoprim e tetraciclina. A maioria das amostras de E. coli foram resistentes ao soro, os outros fatores do virulência, hemolisina e afinidade ao vermelho-congo, foram menos freqüentes nas amostras estudadas. A patogenicidade das amostras de E. coli estimada através da DL50 em ovos embrionados, variaram de 8x10* a 3.2x10a.

  4. Stereoselective Synthesis of 1-Tuberculosinyl Adenosine; a Virulence Factor of Mycobacterium tuberculosis.

    Science.gov (United States)

    Buter, Jeffrey; Heijnen, Dorus; Wan, Ieng Chim; Bickelhaupt, F Matthias; Young, David C; Otten, Edwin; Moody, D Branch; Minnaard, Adriaan J

    2016-08-05

    Despite its status as one of the world's most prevalent and deadly bacterial pathogens, Mycobacterium tuberculosis (Mtb) infection is not routinely diagnosed by rapid and highly reliable tests. A program to discover Mtb-specific biomarkers recently identified two natural compounds, 1-tuberculosinyl adenosine (1-TbAd) and N(6)-tuberculosinyl adenosine (N(6)-TbAd). Based on their association with virulence, the lack of similar compounds in nature, the presence of multiple stereocenters, and the need for abundant products to develop diagnostic tests, synthesis of these compounds was considered to be of high value but challenging. Here, a multigram-scale stereoselective synthesis of 1-TbAd and N(6)-TbAd is described. As a key-step, a chiral auxiliary-mediated Diels-Alder cycloaddition was developed, introducing the three stereocenters with a high exo endo ratio (10:1) and excellent enantioselectivity (>98% ee). This constitutes the first entry into the stereoselective synthesis of diterpenes with the halimane skeleton. Computational studies explain the observed stereochemical outcome.

  5. The PecT repressor coregulates synthesis of exopolysaccharides and virulence factors in Erwinia chrysanthemi.

    Science.gov (United States)

    Condemine, G; Castillo, A; Passeri, F; Enard, C

    1999-01-01

    Erwinia chrysanthemi 3937 synthesizes an exopolysaccharide (EPS) composed of rhamnose, galactose, and galacturonic acid. Fourteen transcriptional fusions in genes required for EPS synthesis, named eps, were obtained by Tn5-B21 mutagenesis. Eleven of them are clustered on the chromosome and are repressed by PecT, a regulator of pectate lyase synthesis. In addition, expression of these fusions is repressed by the catabolite regulatory protein, CRP, and induced in low osmolarity medium. The three other mutations are located in genes that are not regulated by pecT. A 13-kb DNA fragment containing pecT-regulated eps genes has been cloned. All the genes identified on this fragment are transcribed in the same orientation and could form a large operon. The promoter region of this operon has been sequenced. It contains a JUMP-start sequence, a sequence required for the expression of polysaccharide-associated operons. E. chrysanthemi 3937 produces a systemic soft rot on its host Saintpaulia ionantha. An eps mutant was less efficient than the wild-type strain in initiating a maceration symptom, suggesting that production of EPS is required for the full expression of the E. chrysanthemi virulence.

  6. Co-aggregation as a virulent factor of Streptococcus sanguis isolated from infective endocarditis.

    Science.gov (United States)

    Ochiai, K; Kikuchi, K; Fukushima, K; Kurita-Ochiai, T

    1999-09-01

    The pathogenicity of strains of the Streptococcus sanguis group, isolated from infective endcarditis, was studied by measuring the development of subcutaneous abscesses in mice after infection with S. sanguis and Actinomyces viscosus either singly or as co-aggregated pairs. The pathogenicity of the co-aggregates was also examined in various viable combinations of the two bacterial species. More abscesses were formed by A. viscosus than the S. sanguis group including clinical isolates. Abscess formation by co-aggregates of combinations of each isolate and A. viscosus produced a higher percentage of abscess formation than those caused by infection with a pure suspension of A. viscosus or tested streptococci. Co-aggregated cells were more resistant to phagocytosis and killing by neutrophils in vivo. These results indicated that S. sanguis group streptococci isolated from infective endocarditis are able to co-aggregate and resist phagocytosis. The ability of co-aggregation of S. sanguis may serve as a survival mechanism in a host defense system and may be linked with virulence of this bacteria.

  7. Co-regulation of Iron Metabolism and Virulence Associated Functions by Iron and XibR, a Novel Iron Binding Transcription Factor, in the Plant Pathogen Xanthomonas.

    Science.gov (United States)

    Pandey, Sheo Shankar; Patnana, Pradeep Kumar; Lomada, Santosh Kumar; Tomar, Archana; Chatterjee, Subhadeep

    2016-11-01

    Abilities of bacterial pathogens to adapt to the iron limitation present in hosts is critical to their virulence. Bacterial pathogens have evolved diverse strategies to coordinately regulate iron metabolism and virulence associated functions to maintain iron homeostasis in response to changing iron availability in the environment. In many bacteria the ferric uptake regulator (Fur) functions as transcription factor that utilize ferrous form of iron as cofactor to regulate transcription of iron metabolism and many cellular functions. However, mechanisms of fine-tuning and coordinated regulation of virulence associated function beyond iron and Fur-Fe2+ remain undefined. In this study, we show that a novel transcriptional regulator XibR (named Xanthomonas iron binding regulator) of the NtrC family, is required for fine-tuning and co-coordinately regulating the expression of several iron regulated genes and virulence associated functions in phytopathogen Xanthomonas campestris pv. campestris (Xcc). Genome wide expression analysis of iron-starvation stimulon and XibR regulon, GUS assays, genetic and functional studies of xibR mutant revealed that XibR positively regulates functions involved in iron storage and uptake, chemotaxis, motility and negatively regulates siderophore production, in response to iron. Furthermore, chromatin immunoprecipitation followed by quantitative real-time PCR indicated that iron promoted binding of the XibR to the upstream regulatory sequence of operon's involved in chemotaxis and motility. Circular dichroism spectroscopy showed that purified XibR bound ferric form of iron. Electrophoretic mobility shift assay revealed that iron positively affected the binding of XibR to the upstream regulatory sequences of the target virulence genes, an effect that was reversed by ferric iron chelator deferoxamine. Taken together, these data revealed that how XibR coordinately regulates virulence associated and iron metabolism functions in Xanthomonads in

  8. Staphylococcus aureus Hemolysins, bi-component Leukocidins, and Cytolytic Peptides: A Redundant Arsenal of Membrane-Damaging Virulence Factors?

    Science.gov (United States)

    Vandenesch, François; Lina, G.; Henry, Thomas

    2012-01-01

    One key aspect of the virulence of Staphylococcus aureus lies in its ability to target the host cell membrane with a large number of membrane-damaging toxins and peptides. In this review, we describe the hemolysins, the bi-component leukocidins (which include the Panton Valentine leukocidin, LukAB/GH, and LukED), and the cytolytic peptides (phenol soluble modulins). While at first glance, all of these factors might appear redundant, it is now clear that some of these factors play specific roles in certain S. aureus life stages and diseases or target specific cell types or species. In this review, we present an update of the literature on toxin receptors and their cell type and species specificities. Furthermore, we review epidemiological studies and animal models illustrating the role of these membrane-damaging factors in various diseases. Finally, we emphasize the interplay of these factors with the host immune system and highlight all their non-lytic functions. PMID:22919604

  9. Comparative genomics reveals cotton-specific virulence factors in flexible genomic regions in Verticillium dahliae and evidence of horizontal gene transfer from Fusarium.

    Science.gov (United States)

    Chen, Jie-Yin; Liu, Chun; Gui, Yue-Jing; Si, Kai-Wei; Zhang, Dan-Dan; Wang, Jie; Short, Dylan P G; Huang, Jin-Qun; Li, Nan-Yang; Liang, Yong; Zhang, Wen-Qi; Yang, Lin; Ma, Xue-Feng; Li, Ting-Gang; Zhou, Lei; Wang, Bao-Li; Bao, Yu-Ming; Subbarao, Krishna V; Zhang, Geng-Yun; Dai, Xiao-Feng

    2018-01-01

    Verticillium dahliae isolates are most virulent on the host from which they were originally isolated. Mechanisms underlying these dominant host adaptations are currently unknown. We sequenced the genome of V. dahliae Vd991, which is highly virulent on its original host, cotton, and performed comparisons with the reference genomes of JR2 (from tomato) and VdLs.17 (from lettuce). Pathogenicity-related factor prediction, orthology and multigene family classification, transcriptome analyses, phylogenetic analyses, and pathogenicity experiments were performed. The Vd991 genome harbored several exclusive, lineage-specific (LS) genes within LS regions (LSRs). Deletion mutants of the seven genes within one LSR (G-LSR2) in Vd991 were less virulent only on cotton. Integration of G-LSR2 genes individually into JR2 and VdLs.17 resulted in significantly enhanced virulence on cotton but did not affect virulence on tomato or lettuce. Transcription levels of the seven LS genes in Vd991 were higher during the early stages of cotton infection, as compared with other hosts. Phylogenetic analyses suggested that G-LSR2 was acquired from Fusarium oxysporum f. sp. vasinfectum through horizontal gene transfer. Our results provide evidence that horizontal gene transfer from Fusarium to Vd991 contributed significantly to its adaptation to cotton and may represent a significant mechanism in the evolution of an asexual plant pathogen. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  10. Halogenated furanones from the red alga, Delisea pulchra, inhibit carbapenem antibiotic synthesis and exoenzyme virulence factor production in the phytopathogen Erwinia carotovora

    DEFF Research Database (Denmark)

    Manefield, M.; Welch, M.; Givskov, Michael Christian

    2001-01-01

    The plant pathogen Erwinia carotovora regulates expression of virulence factors and antibiotic production via an N-3- oxohexanoyl-L-homoserine lactone (3-oxo-C6-HSL) dependent quorum sensing mechanism. The marine alga Delisea pulchra produces halogenated furanones known to antagonise 3-oxo-C6-HSL...

  11. Virulence factors and phylogenetic grouping of Escherichia coli isolates from patients with bacteraemia of urinary tract origin relate to sex and hospital- vs. community-acquired origin

    DEFF Research Database (Denmark)

    Skjøt-Rasmussen, Line; Ejrnæs, Karen; Lundgren, Bettina

    2012-01-01

    of urinary tract origin according to virulence-associated genes (VAGs), phylogroups, and antimicrobial resistance, and the relation of these factors to hospital- vs. community-acquired origin, sex, and mortality. We found papAH to be associated with community-acquired (CA) rather than hospital-acquired (HA...... between the epidemiology and pathogenesis of E. coli bacteraemia of urinary tract origin....

  12. Virulence associated factors and antibiotic sensitivity pattern of Escherichia coli isolated from cattle and soil

    Directory of Open Access Journals (Sweden)

    Parul

    2014-05-01

    Full Text Available Aim: The present study was conducted to isolate pathogenic Escherichia coli from the faeces of apparently healthy cattle and soil of the farms to determine their susceptibility to commonly used antibiotics. Materials and Methods: A total of 90 samples (70 faecal and 20 soil samples were collected aseptically and processed under required conditions for the isolation of E. coli. To confirm the isolates as E. coli, various biochemical tests like IMViC were performed. To assess the virulence of isolates, they were subjected to Congo red dye assay and hemolysis assay. Antibiotic sensitivity pattern of pathogenic isolates was studied by Disc diffusion method. Results: The prevalence of E. coli was observed to be 85.71% and 20% from the faecal and soil samples, respectively. Based on the phenotypic characteristics on CT SMAC and MUG Sorbitol, none of the isolates were found to be E. coli O157. The percent positivity on Congo red dye assay was 44.28% for faeces and 5% for soil while only faecal E. coli (4.28% were found to be positive for hemolysis assay. The antibiogram of all 35 pathogenic isolates against 8 antibiotics showed that majority of pathogenic strains exhibited high level of sensitivity to Ceftriaxone (95%, Ciprofloxacin (93%, Amikacin (90%, Gentamycin (89% and low level of sensitivity against Ampicillin (8% and Streptomycin (5%. All isolates were 100% resistant to Amoxicillin and Tetracycline. Conclusion: Cattle act as main reservoirs of pathogenic E. coli that may enter the food chain by faecal contamination and pose potential public health hazards.

  13. Genotypes, antibiotic resistance, and virulence factors of staphylococci from ready-to-eat food.

    Science.gov (United States)

    Podkowik, Magdalena; Bystroń, Jarosław; Bania, Jacek

    2012-01-01

    Sixty-seven staphylococcal isolates belonging to 12 species were obtained from 70 ready-to-eat food products. Staphylococcus aureus (n=25), and Staphylococcus epidermidis (n=13) were dominant. Susceptibility to penicillin, oxacillin, tetracycline, clindamycin, gentamicin, erythromycin, ciprofloxacin, and vancomycin was determined. All investigated S. aureus isolates were resistant to at least one antibiotic, and fifteen isolates were resistant to four and more antibiotics. Thirty-eight coagulase-negative staphylococci (CNS) isolates were resistant to at least one antibiotic, and seventeen to four and more antibiotics. Fifteen CNS isolates were mecA positive, and grew in the presence of 6 μg/mL oxacillin. All S. aureus isolates were mecA-negative. Arginine catabolic mobile element (ACME) was found in seven S. epidermidis isolates. Five S. epidermidis isolates harbored ica operon, ACME and were able to form biofilm. Three of them also possessed IS256 element and were mecA-positive. The expression of icaA gene was comparable in five ica-positive S. epidermidis isolates. One of six mecA positive S. epidermidis isolates was classified as sequence type (ST)155, one as ST110, and two as ST88. Two methicillin-resistant Staphylococcus epidermis (MRSE) belonged to new STs, that is, ST362, and ST363. Enterotoxin genes were found in 92% of S. aureus isolates. No enterotoxin gene was detected in analyzed CNS population. We show that ready-to-eat products are an important source of antibiotic-resistant CNS and potentially virulent strains of S. epidermidis, including genotypes undistinguishable from hospital-adapted clones.

  14. Crystallization and preliminary X-ray diffraction analysis of BipD, a virulence factor from Burkholderia pseudomallei

    Energy Technology Data Exchange (ETDEWEB)

    Knight, M. J.; Ruaux, A.; Mikolajek, H.; Erskine, P. T.; Gill, R.; Wood, S. P. [School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton SO16 7PX (United Kingdom); Wood, M. [Institute of Animal Health, Division of Environmental Microbiology, Institute for Animal Health, Compton Laboratory, Berkshire RG20 7NN (United Kingdom); Cooper, J. B., E-mail: j.b.cooper@soton.ac.uk [School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton SO16 7PX (United Kingdom)

    2006-08-01

    BipD is likely to be a component of a type-III protein secretion system (TTSS) in B. pseudomallei. Native and selenomethionyl-BipD proteins have been expressed and crystals have been obtained which diffract to 2.1 Å. Burkholderia pseudomallei, the causative agent of melioidosis, possesses a protein-secretion apparatus that is similar to those found in Salmonella and Shigella. A major function of these secretion systems is to secrete virulence-associated proteins into target cells of the host organism. The BipD gene of B. pseudomallei encodes a secreted virulence factor that is similar in sequence and most likely functionally analogous to IpaD from Shigella and SipD from Salmonella. Thus, the BipD protein is likely to be a component of a type III protein-secretion system (TTSS) in B. pseudomallei. Proteins in the same class as BipD, such as IpaD and SipD, are thought to act as extracellular chaperones to help the hydrophobic translocator proteins enter the target cell membrane, where they form a pore and might even link the translocon pore with the secretion needle. There is evidence that the translocator proteins also bind an integrin which stimulates actin-mediated insertion of the bacterium into the host-cell membrane. Native BipD has been crystallized in a monoclinic crystal form that diffracts X-rays to 2.5 Å resolution. BipD protein which incorporates selenomethionine (SeMet-BipD) has also been expressed and forms crystals which diffract to a higher resolution of 2.1 Å.

  15. Prevalence of virulence factors in Escherichia coli strains isolated from the genital tract of healthy cows Prevalência de fatores de virulência em cepas de Escherichia coli isoladas do trato genital de vacas saudáveis

    Directory of Open Access Journals (Sweden)

    D. Resende

    2007-06-01

    Full Text Available The prevalence of virulence genes expressing fimbriae, production of hemolysin, colicin and aerobactin, was determined in Escherichia coli isolates from healthy cow’s genital tract not showing clinical signs of infection. The presence of fimbriae expression genes (pap, sfa, afa was assayed using specific primers in a polymerase chain reaction; none were detected in any of the isolates. Yet, a prevalence of 90.4%, 69.8%, and 28.5% of virulence factors for colicin, hemolysin and aerobactin respectively, was detected in the isolates. Analysis of the bacterial pathogenicity of isolates from the bovine genital tract may contribute towards the understanding of E. coli behavior.Determinou-se a prevalência dos genes de virulência expressando fimbrias, produção de hemolisina, colicina e aerobactina em cepas de Escherichia coli obtidas do trato genital de vacas saudáveis que não apresentam sinais clínicos indicativos de infecção. A presença dos genes responsáveis pela expressão de fimbrias (pap, sfa, afa foi avaliada através de reação em cadeia da polimerase utilizando primers especificos para cada um dos genes, nenhum deles foi detectado em qualquer uma das cepas isoladas. A prevalência dos fatores de virulência foi de 90,4%, 69,8%, 28,5% para colicina, hemolisina e aerobactina, respectivamente. A análise da patogenicidade das cepas do trato genital pode contribuir para o entendimento do comportamento das cepas de E. coli.

  16. MADS-box transcription factor SsMADS is involved in regulating growth and virulence in Sclerotinia sclerotiorum.

    Science.gov (United States)

    Qu, Xiaoyan; Yu, Baodong; Liu, Jinliang; Zhang, Xianghui; Li, Guihua; Zhang, Dongjing; Li, Le; Wang, Xueliang; Wang, Lu; Chen, Jingyuan; Mu, Wenhui; Pan, Hongyu; Zhang, Yanhua

    2014-05-08

    MADS-box proteins, a well-conserved family of transcription factors in eukaryotic organisms, specifically regulate a wide range of cellular functions, including primary metabolism, cell cycle, and cell identity. However, little is known about roles of the MADS-box protein family in the fungal pathogen Sclerotinia sclerotiorum. In this research, the S. sclerotiorum MADS-box gene SsMADS was cloned; it encodes a protein that is highly similar to Mcm1 orthologs from Saccharomyces cerevisiae and other fungi, and includes a highly conserved DNA-binding domain. MADS is a member of the MADS box protein SRF (serum response factor) lineage. SsMADS function was investigated using RNA interference. Silenced strains were obtained using genetic transformation of the RNA interference vectors pS1-SsMADS and pSD-SsMADS. SsMADS expression levels in silenced strains were analyzed using RT-PCR. The results showed that SsMADS mRNA expression in these silenced strains was reduced to different degrees, and growth rate in these silenced strains was significantly decreased. Infecting tomato leaflets with silenced strains indicated that SsMADS was required for leaf pathogenesis in a susceptible host. Our results suggest that the MADS-box transcription factor SsMADS is involved in S. sclerotiorum growth and virulence.

  17. Rice bacterial blight pathogen Xanthomonas oryzae pv. oryzae produces multiple DSF-family signals in regulation of virulence factor production

    Directory of Open Access Journals (Sweden)

    Cha Jae-Soon

    2010-07-01

    Full Text Available Abstract Background Xanthomonas oryzae pv. oryzae (Xoo is the causal agent of rice bacterial blight disease. Xoo produces a range of virulence factors, including EPS, extracellular enzyme, iron-chelating siderophores, and type III-secretion dependent effectors, which are collectively essential for virulence. Genetic and genomics evidence suggest that Xoo might use the diffusible signal factor (DSF type quorum sensing (QS system to regulate the virulence factor production. However, little is known about the chemical structure of the DSF-like signal(s produced by Xoo and the factors influencing the signal production. Results Xoo genome harbours an rpf cluster comprising rpfB, rpfF, rpfC and rpfG. The proteins encoded by these genes are highly homologous to their counterparts in X. campestris pv. campestris (Xcc, suggesting that Xcc and Xoo might use similar mechanisms for DSF biosynthesis and autoregulation. Consistent with in silico analysis, the rpfF mutant was DSF-deficient and the rpfC mutant produced about 25 times higher DSF-like activity than the wild type Xoo strain KACC10331. From the supernatants of rpfC mutant, we purified three compounds showing strong DSF-like activity. Mass spectrometry and NMR analysis revealed that two of them were the previously characterized DSF and BDSF; the third one was a novel unsaturated fatty acid with 2 double bonds and was designated as CDSF in this study. Further analysis showed that all the three DSF-family signals were synthesized via the enzyme RpfF encoded by Xoo2868. DSF and BDSF at a final concentration of 3 μM to the rpfF mutant could fully restore its extracellular xylanase activity and EPS production to the wild type level, but CDSF was less active than DSF and BDSF in induction of EPS and xylanase. DSF and CDSF shared a similar cell density-dependent production time course with the maximum production being detected at 42 h after inoculation, whereas the maximum production of BDSF was observed

  18. Relevance of Helicobacter pylori virulence factors for vaccine development Relevancia de los factores de virulencia de helicobacter pylori para el desarrollo de vacunas

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    Luz del Carmen Hernández-Hernández

    2009-01-01

    Full Text Available Helicobacter pylori infection increases the risk for a wide spectrum of clinical outcomes, ranging from peptic ulcer disease to gastric cancer. However, the infection induces gastric and duodenal ulceration or gastric cancer in only a minority of infected subjects because H. pylori strains are genetically diverse and express different virulence factors. Individuals infected with strains that express these virulence factors probably develop severe diseases such as gastric cancer. Nevertheless, the ancient relationship between H. pylori and humans suggests that some strains could be beneficial to human health, which means that generalized administration of antibiotic therapy could eventually cause problems. The development of vaccines based on virulence factors that provide long-term protection is the best strategy for control and/or elimination of pathogenic strains. The different immunization schemes and formulations designed to evaluate the vaccines based on virulence factors in animal models have offered promising results. However, it is necessary to determine whether or not these results can be reproduced in humans. This article reviews recent vaccination studies that explore this possibility: oral vaccines using urease or inactivated whole cells plus LT as adjuvant and urease expressed in Salmonella spp. vectors, as well as a parenteral multicomponent vaccine plus aluminum hydroxide as adjuvant. Although these studies have achieved limited success, they have established support for the development of an effective vaccine against this infection.La infección por Helicobacter pylori incrementa el riesgo de un amplio espectro de cuadros clínicos, que van de la úlcera péptica al cáncer gástrico. Sin embargo, la infección sólo induce ulceración gástrica y duodenal o cáncer gástrico en la minoría de los sujetos infectados debido que las cepas de H. pylori son genéticamente diversas y expresan diferentes factores de virulencia. As

  19. Phylogenetic group distributions, virulence factors and antimicrobial resistance properties of uropathogenic Escherichia coli strains isolated from patients with urinary tract infections in South Korea.

    Science.gov (United States)

    Lee, J H; Subhadra, B; Son, Y-J; Kim, D H; Park, H S; Kim, J M; Koo, S H; Oh, M H; Kim, H-J; Choi, C H

    2016-01-01

    Urinary tract infections (UTIs) are one of the most common diseases by which humans seek medical help and are caused mainly by uropathogenic Escherichia coli (UPEC). Studying the virulence and antibiotic resistance of UPEC with respect to various phylogenetic groups is of utmost importance in developing new therapeutic agents. Thus, in this study, we analysed the virulence factors, antibiotic resistance and phylogenetic groups among various UPEC isolates from children with UTIs. The phylogenetic analysis revealed that majority of the strains responsible for UTIs belonged to the phylogenetic groups B2 and D. Of the 58 E. coli isolates, 79·31% belonged to group B2, 15·51% to group D, 3·44% to group A and 1·72% to B1. Simultaneously, the number of virulence factors and antibiotic resistance exhibited were also significantly high in groups B2 and D compared to other groups. Among the isolates, 44·8% were multidrug resistant and of that 73% belonged to the phylogenetic group B2, indicating the compatibility of antibiotic resistance and certain strains carrying virulence factor genes. The antibiotic resistance profiling of UPEC strains elucidates that the antimicrobial agents such as chloramphenicol, cefoxitin, cefepime, ceftazidime might still be used in the therapy for treating UTIs. As the antibiotic resistance pattern of uropathogenic Escherichia coli varies depending on different geographical regions, the antibiotic resistance pattern from this study will help the physicians to effectively administer antibiotic therapy for urinary tract infections. In addition, the frequency of virulence factors and antibiotic resistance genes among various phylogenic groups could be effectively used to draw new targets for uropathogenic Escherichia coli antibiotic-independent therapies. The study emphasizes need of public awareness on multidrug resistance and for more prudent use of antimicrobials. © 2015 The Society for Applied Microbiology.

  20. Colonization and virulence factors of methicillin resistant Staphylococcus aureus in a pediatric population in Montería, Colombia

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    Ricardo-Caldera, Dina Marcela

    2015-07-01

    Full Text Available Introduction: Methicillin-resistant Staphylococcus aureus (MRSA is able to colonize the human body, most frequently the nostrils, but also the hands, perineum and throat. Such colonization has been proposed as a risk factor to acquire future infections. Objective: To determine the prevalence, and the microbiological and molecular characteristics of MRSA in healthy children. Methodology: A cross-sectional descriptive study was done of 150 children from 13 day care centers in Montería, Colombia. Nasal and throat swabs were obtained. The isolates were identified and characterized by microbiological and molecular methods. Results: The MRSA colonization rate was 9.3% (14/150. 62.5% of the isolates carried the subtype IVc of SCCmec, and 87.5% had the genes encoding for PVL and Sek, while 81.2% carried the gene bsaB. Conclusion: The percentage of colonization found is one of the highest reported among children from the Colombian Caribbean region, and the isolates have virulence factors that have been associated with an aggressive clinical course.

  1. Pyocyanin, a virulence factor produced by Pseudomonas aeruginosa, alters root development through reactive oxygen species and ethylene signaling in Arabidopsis.

    Science.gov (United States)

    Ortiz-Castro, Randy; Pelagio-Flores, Ramón; Méndez-Bravo, Alfonso; Ruiz-Herrera, León Francisco; Campos-García, Jesús; López-Bucio, José

    2014-04-01

    Pyocyanin acts as a virulence factor in Pseudomonas aeruginosa, a plant and animal pathogen. In this study, we evaluated the effect of pyocyanin on growth and development of Arabidopsis seedlings. Root inoculation with P. aeruginosa PAO1 strain inhibited primary root growth in wild-type (WT) Arabidopsis seedlings. In contrast, single lasI- and double rhlI-/lasI- mutants of P. aeruginosa defective in pyocyanin production showed decreased root growth inhibition concomitant with an increased phytostimulation. Treatment with pyocyanin modulates root system architecture, inhibiting primary root growth and promoting lateral root and root hair formation without affecting meristem viability or causing cell death. These effects correlated with altered proportions of hydrogen peroxide and superoxide in root tips and with an inhibition of cell division and elongation. Mutant analyses showed that pyocyanin modulation of root growth was likely independent of auxin, cytokinin, and abscisic acid but required ethylene signaling because the Arabidopsis etr1-1, ein2-1, and ein3-1 ethylene-related mutants were less sensitive to pyocyanin-induced root stoppage and reactive oxygen species (ROS) distribution. Our findings suggest that pyocyanin is an important factor modulating the interplay between ROS production and root system architecture by an ethylene-dependent signaling.

  2. Purification, Crystallization and Preliminary X-ray Diffraction Analysis of Cif, a Virulence Factor Secreted by Pseudomonas aeruginosa

    Energy Technology Data Exchange (ETDEWEB)

    Bahl, C.; MacEachran, D; O& apos; Toole, G; Madden, D

    2010-01-01

    The opportunistic pathogen Pseudomonas aeruginosa secretes a protein that triggers the accelerated degradation of the cystic fibrosis transmembrane conductance regulator (CFTR) in airway epithelial cells. This protein, which is known as the CFTR inhibitory factor (Cif), acts as a virulence factor and may facilitate airway colonization by P. aeruginosa. Based on sequence similarity Cif appears to be an epoxide hydrolase (EH), but it lacks several of the conserved features found in the active sites of canonical members of the EH family. Here, the crystallization of purified recombinant Cif by vapor diffusion is reported. The crystals formed in space group C2, with unit-cell parameters a = 167.4, b = 83.6, c = 88.3 {angstrom}, {beta} = 100.6{sup o}. The crystals diffracted to 2.39 {angstrom} resolution on a rotating-anode source. Based on the calculated Matthews coefficient (2.2 {angstrom}{sup 3} Da{sup -1}), it appears that the asymmetric unit contains four molecules.

  3. Resistance to amoxicillin-clavulanate and its relation to virulence-related factors in Yersinia enterocolitica biovar 1A

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    N Singhal

    2016-01-01

    Full Text Available Recent studies have reported that the virulence factors (VFs were detected more frequently in amoxicillin-clavulanate (AMC susceptible clinical isolates of Escherichia coli. Here, we have evaluated the relationship between VFs and AMC-resistance phenotype in clinical isolates of Y. enterocolitica biovar 1A. The presence/absence of VFs was compared with their minimum inhibitory concentrations for AMC in strains of two serovars. We observed that the strains of the serovar O: 6, 30-6, 31 showed a similar relationship between the number of VFs and resistance to clavulanic acid as in E. coli but not of serovar O: 6, 30. Variations in the promoters/complete coding sequences (CCDSs of β-lactamase gene (bla A or the serological characteristics could not account for unusual susceptibility to AMC displayed by the strains of the serovar O: 6, 30. Therefore, we speculate that since the clinical strains of serovar O: 6, 30-6, 31 originated from the environment they were less exposed to antibiotics compared to clinical strains of serovar O: 6, 30. Thus, AMC susceptibility seems to be influenced by factors other than serotypes or promoters/CCDS of β-lactamase genes.

  4. Bioenergetics of lung tumors: Alteration of mitochondrial biogenesis and respiratory kapacity

    Czech Academy of Sciences Publication Activity Database

    Bellance, N.; Benard, G.; Furt, F.; Begueret, H.; Smolková, Katarína; Passerieux, E.; Delage, J.P.; Baste, J.M.; Moreau, P.; Rossignol, R.

    2009-01-01

    Roč. 41, č. 12 (2009), s. 2566-2577 ISSN 1357-2725 Institutional research plan: CEZ:AV0Z50110509 Keywords : tumors * bioenergetics * biogenesis Subject RIV: ED - Physiology Impact factor: 4.887, year: 2009

  5. Virulence factors analysis of Staphylococcus aureus isolated from bovine mastitis in México

    Directory of Open Access Journals (Sweden)

    Julio C. Franco G.

    2008-01-01

    Full Text Available Un total de 117 aislados bacterianos obtenidos de casos de mastitis bovina positivos a las pruebas de catalasa, coagulasa, termonucleasa, manitol y PCR fueron analizados para determinar la producción de los siguientes factores de virulencia: hemolisisnas (alfa y beta, factor de agregación y cápsula. Adicionalmente fue también evaluada la sensibilidad a oxitetraciclina, penicilina, oxacilina y estreptomicina. La producción de hemolisinas y el factor de agregación fueron los 2 factores de virulencia expresados en la mayoría de los aislados (78% y (83% respectivamente, mientras que la formación de cápsula se detectó en 31% de los aislados bovinos. Una fuerte correlación entre ausencia de cápsula y producción de hemolisinas fue observado, ya que 72 de un total de 92 cepas hemolíticas no mostraron cápsula. La ausencia de cápsula fue asociada a la producción del factor de agregación en 89% de los aislados bacterianos positivos a este factor. El 68% y 69% de los aislados bacterianos resultaron positivos a penicilina y oxacilina respectivamente. La mayoría de los aislados (116 expresaron al menos 1 factor de virulencia (hemolisinas, cápsula o factor de agregación. Finalmente, el papel de los factores de virulencia y su relación en la patogenicidad de S. aureus en la mastitis bovina en México es discutido.

  6. The origin of endodontic Enterococcus faecalis explored by comparison of virulence factor patterns and antibiotic resistance to that of isolates from stool samples, blood cultures and food.

    Science.gov (United States)

    Vidana, R; Rashid, M U; Özenci, V; Weintraub, A; Lund, B

    2016-04-01

    To elucidate the origin of Enterococcus faecalis isolated from secondary root canal infections and the possibility for a foodborne transmission by comparing them to strains recovered from food, blood and stool regarding putative virulence factors and antibiotic susceptibility profiles, where strains from common origin were hypothesized to harbour similar characteristics. A total of 108 E. faecalis strains recovered in the county of Stockholm, Sweden, were screened using PCR for putative virulence factors esp, cylA, gelE/gelatinase-negative phenotype (ef1841/fsrC), efaA, ace and asa1. The minimum inhibitory concentration (MIC) for ampicillin, piperacillin-tazobactam, imipenem, gentamicin, vancomycin, ciprofloxacin and linezolid was determined using the agar dilution method. Next to strains from blood, the food isolates presented the highest average number of virulence determinants and were frequently enriched with asa1 coding for aggregation substance. None of the endodontic strains carried cylA, and the gelatinase-negative phenotype caused by a deletion dominated the group. Altogether, the most prevalent genes were gelE, efaA and ace, and a combination of them was equally present in approximately 80% of the strains from food, stool and root canals in comparison with 43.3% of the blood isolates. High-level resistance to ciprofloxacin and gentamicin was observed in 30% of the blood isolates, whereas the isolates from other origins, with single exceptions, were susceptible to all tested antibiotics. Evidence for a foodborne transmission, explaining the high reported prevalence of E. faecalis in root filled teeth, could not be determined based on the similarities in virulence factor patterns and antibiotic susceptibility. The only linkage between isolates from food and root canals consisted of a shared common combination of the genes gelE, efaA and ace. The high occurrence of putative virulence traits in food isolates questions the safety of E. faecalis in food

  7. Occurrence of virulence factors and antimicrobial resistance in Pasteurella multocida strains isolated from slaughter cattle in Iran

    National Research Council Canada - National Science Library

    Khamesipour, Faham; Momtaz, Hassan; Azhdary Mamoreh, Morteza

    2014-01-01

    A total of 30 Pasteurella multocida strains isolated from 333 pneumonic and apparently health slaughter cattle were examined for capsule biosynthesis genes and 23 virulence-associated genes by polymerase chain reaction (PCR...

  8. ERES : sites for autophagosome biogenesis and maturation?

    NARCIS (Netherlands)

    Sanchez-Wandelmer, Jana; Ktistakis, Nicholas T; Reggiori, Fulvio

    2015-01-01

    Autophagosomes are the hallmark of autophagy, but despite their central role in this degradative pathway that involves vesicle transport to lysosomes or vacuoles, the mechanism underlying their biogenesis still remains largely unknown. Our current concepts about autophagosome biogenesis are based on

  9. A Comprehensive Functional Portrait of Two Heat Shock Factor-Type Transcriptional Regulators Involved in Candida albicans Morphogenesis and Virulence

    Science.gov (United States)

    Znaidi, Sadri; Nesseir, Audrey; Chauvel, Murielle; Rossignol, Tristan; d'Enfert, Christophe

    2013-01-01

    Sfl1p and Sfl2p are two homologous heat shock factor-type transcriptional regulators that antagonistically control morphogenesis in Candida albicans, while being required for full pathogenesis and virulence. To understand how Sfl1p and Sfl2p exert their function, we combined genome-wide location and expression analyses to reveal their transcriptional targets in vivo together with the associated changes of the C. albicans transcriptome. We show that Sfl1p and Sfl2p bind to the promoter of at least 113 common targets through divergent binding motifs and modulate directly the expression of key transcriptional regulators of C. albicans morphogenesis and/or virulence. Surprisingly, we found that Sfl2p additionally binds to the promoter of 75 specific targets, including a high proportion of hyphal-specific genes (HSGs; HWP1, HYR1, ECE1, others), revealing a direct link between Sfl2p and hyphal development. Data mining pointed to a regulatory network in which Sfl1p and Sfl2p act as both transcriptional activators and repressors. Sfl1p directly represses the expression of positive regulators of hyphal growth (BRG1, UME6, TEC1, SFL2), while upregulating both yeast form-associated genes (RME1, RHD1, YWP1) and repressors of morphogenesis (SSN6, NRG1). On the other hand, Sfl2p directly upregulates HSGs and activators of hyphal growth (UME6, TEC1), while downregulating yeast form-associated genes and repressors of morphogenesis (NRG1, RFG1, SFL1). Using genetic interaction analyses, we provide further evidences that Sfl1p and Sfl2p antagonistically control C. albicans morphogenesis through direct modulation of the expression of important regulators of hyphal growth. Bioinformatic analyses suggest that binding of Sfl1p and Sfl2p to their targets occurs with the co-binding of Efg1p and/or Ndt80p. We show, indeed, that Sfl1p and Sfl2p targets are bound by Efg1p and that both Sfl1p and Sfl2p associate in vivo with Efg1p. Taken together, our data suggest that Sfl1p and Sfl2p act as

  10. A comprehensive functional portrait of two heat shock factor-type transcriptional regulators involved in Candida albicans morphogenesis and virulence.

    Science.gov (United States)

    Znaidi, Sadri; Nesseir, Audrey; Chauvel, Murielle; Rossignol, Tristan; d'Enfert, Christophe

    2013-08-01

    Sfl1p and Sfl2p are two homologous heat shock factor-type transcriptional regulators that antagonistically control morphogenesis in Candida albicans, while being required for full pathogenesis and virulence. To understand how Sfl1p and Sfl2p exert their function, we combined genome-wide location and expression analyses to reveal their transcriptional targets in vivo together with the associated changes of the C. albicans transcriptome. We show that Sfl1p and Sfl2p bind to the promoter of at least 113 common targets through divergent binding motifs and modulate directly the expression of key transcriptional regulators of C. albicans morphogenesis and/or virulence. Surprisingly, we found that Sfl2p additionally binds to the promoter of 75 specific targets, including a high proportion of hyphal-specific genes (HSGs; HWP1, HYR1, ECE1, others), revealing a direct link between Sfl2p and hyphal development. Data mining pointed to a regulatory network in which Sfl1p and Sfl2p act as both transcriptional activators and repressors. Sfl1p directly represses the expression of positive regulators of hyphal growth (BRG1, UME6, TEC1, SFL2), while upregulating both yeast form-associated genes (RME1, RHD1, YWP1) and repressors of morphogenesis (SSN6, NRG1). On the other hand, Sfl2p directly upregulates HSGs and activators of hyphal growth (UME6, TEC1), while downregulating yeast form-associated genes and repressors of morphogenesis (NRG1, RFG1, SFL1). Using genetic interaction analyses, we provide further evidences that Sfl1p and Sfl2p antagonistically control C. albicans morphogenesis through direct modulation of the expression of important regulators of hyphal growth. Bioinformatic analyses suggest that binding of Sfl1p and Sfl2p to their targets occurs with the co-binding of Efg1p and/or Ndt80p. We show, indeed, that Sfl1p and Sfl2p targets are bound by Efg1p and that both Sfl1p and Sfl2p associate in vivo with Efg1p. Taken together, our data suggest that Sfl1p and Sfl2p act as

  11. Trans-Cinnamaldehyde, Carvacrol, and Eugenol Reduce Campylobacter jejuni Colonization Factors and Expression of Virulence Genes in Vitro.

    Science.gov (United States)

    Upadhyay, Abhinav; Arsi, Komala; Wagle, Basanta R; Upadhyaya, Indu; Shrestha, Sandip; Donoghue, Ann M; Donoghue, Dan J

    2017-01-01

    Campylobacter jejuni is a major foodborne pathogen that causes severe gastroenteritis in humans characterized by fever, diarrhea, and abdominal cramps. In the human gut, Campylobacter adheres and invades the intestinal epithelium followed by cytolethal distending toxin mediated cell death, and enteritis. Reducing the attachment and invasion of Campylobacter to intestinal epithelium and expression of its virulence factors such as motility and cytolethal distending toxin (CDT) production could potentially reduce infection in humans. This study investigated the efficacy of sub-inhibitory concentrations (SICs, concentration not inhibiting bacterial growth) of three GRAS (generally recognized as safe) status phytochemicals namely trans-cinnamaldehyde (TC; 0.005, 0.01%), carvacrol (CR; 0.001, 0.002%), and eugenol (EG; 0.005, 0.01%) in reducing the attachment, invasion, and translocation of C. jejuni on human intestinal epithelial cells (Caco-2). Additionally, the effect of these phytochemicals on Campylobacter motility and CDT production was studied using standard bioassays and gene expression analysis. All experiments had duplicate samples and were replicated three times on three strains (wild type S-8, NCTC 11168, 81-176) of C. jejuni. Data were analyzed using ANOVA with GraphPad ver. 6. Differences between the means were considered significantly different at P jejuni adhesion, invasion, and translocation of Caco-2 cells (P jejuni genes critical for infection in humans (P jejuni infection in humans.

  12. Differences in Extended-Spectrum Beta-Lactamase Producing Escherichia coli Virulence Factor Genes in the Baltic Sea Region

    Directory of Open Access Journals (Sweden)

    Jana Lillo

    2014-01-01

    Full Text Available The aim of this study was to compare the prevalence of different virulence factor (VF genes in extended-spectrum beta-lactamase (ESBL producing Escherichia coli strains isolated from the Baltic Sea region. A total of 432 strains of phenotypically ESBL positive E. coli were collected from 20 institutions located in Estonia, Latvia, Lithuania, and the region of St. Petersburg in Russia from January to May 2012 and analyzed for phylogenetic group and prevalence of 23 VF genes. The strains were collected from clinical material (urine, blood, wound, and respiratory tract. Bacterial isolates were compared according to phylogenetic group, clinical material, and geographical origin. Most of the VF genes were concentrated within phylogenetic group B2 and/or D. When comparing strains isolated from different countries, it was found that strains originating from Estonia and Latvia belonged mainly to group B2 and strains from Lithuania and Russia mainly to groups B2 and D. The P-fimbrial adhesin gene papEF was more prevalent in Russian strains, colicin gene cvaC in Lithuanian strains, and capsular gene kpsMTII in Latvian strains; serum resistant gene traT was less prevalent in Estonian strains. The regional differences of VF genes remained statistically significant after taking into account the phylogenetic distribution in the countries.

  13. UroPathogenic Escherichia coli (UPEC) Infections: Virulence Factors, Bladder Responses, Antibiotic, and Non-antibiotic Antimicrobial Strategies.

    Science.gov (United States)

    Terlizzi, Maria E; Gribaudo, Giorgio; Maffei, Massimo E

    2017-01-01

    Urinary tract infections (UTIs) are one of the most common pathological conditions in both community and hospital settings. It has been estimated that about 150 million people worldwide develop UTI each year, with high social costs in terms of hospitalizations and medical expenses. Among the common uropathogens associated to UTIs development, UroPathogenic Escherichia coli (UPEC) is the primary cause. UPEC strains possess a plethora of both structural (as fimbriae, pili, curli, flagella) and secreted (toxins, iron-acquisition systems) virulence factors that contribute to their capacity to cause disease, although the ability to adhere to host epithelial cells in the urinary tract represents the most important determinant of pathogenicity. On the opposite side, the bladder epithelium shows a multifaceted array of host defenses including the urine flow and the secretion of antimicrobial substances, which represent useful tools to counteract bacterial infections. The fascinating and intricate dynamics between these players determine a complex interaction system that needs to be revealed. This review will focus on the most relevant components of UPEC arsenal of pathogenicity together with the major host responses to infection, the current approved treatment and the emergence of resistant UPEC strains, the vaccine strategies, the natural antimicrobial compounds along with innovative anti-adhesive and prophylactic approaches to prevent UTIs.

  14. Trichosporon asahii causing nosocomial urinary tract infections in intensive care unit patients: genotypes, virulence factors and antifungal susceptibility testing.

    Science.gov (United States)

    Sun, Wei; Su, Jianrong; Xu, Shuzhen; Yan, Donghui

    2012-12-01

    Trichosporon asahii is the causative agent of both superficial and deep-seated infections of increasing morbidity and mortality. Urinary tract infections (UTIs) due to T. asahii, frequently associated with indwelling medical devices, have been reported over the years. However, few studies have specifically focused on the genotypic diversity of T. asahii isolates from urine specimens from intensive care units (ICUs), let alone potential virulence factors and antifungal susceptibility testing. In the present study, 23 T. asahii isolates were collected from UTI patients in ICUs between January 2008 and January 2012. Three genotypes (I, III, IV) were determined based on the combination of internal transcribed spacer and intergenic spacer locus PCR. Protease, phospholipase and haemolysin production was assessed by halo formation on corresponding agar plates. Only haemolytic activity was observed to varying degrees. Neither protease nor phospholipase was detectable. Biofilm formation on polystyrene surfaces was detected through a formazan salt reduction assay. All clinical isolates had the ability to form biofilm. In contrast to the susceptibility of planktonic T. asahii cells to clinically used amphotericin B, 5-flucytosine, fluconazole, itraconazole and voriconazole, a remarkable rise in the MICs of these for biofilm T. asahii cells was observed. Our results suggested that genotype IV was the most prevalent genotype among T. asahii isolates from ICUs in China. Haemolysin and biofilm might contribute to the pathogenicity and recurrence of T. asahii-related UTIs. Although triazoles, especially voriconazole, were effective against planktonic T. asahii cells, they failed to treat preformed biofilms.

  15. UroPathogenic Escherichia coli (UPEC) Infections: Virulence Factors, Bladder Responses, Antibiotic, and Non-antibiotic Antimicrobial Strategies

    Science.gov (United States)

    Terlizzi, Maria E.; Gribaudo, Giorgio; Maffei, Massimo E.

    2017-01-01

    Urinary tract infections (UTIs) are one of the most common pathological conditions in both community and hospital settings. It has been estimated that about 150 million people worldwide develop UTI each year, with high social costs in terms of hospitalizations and medical expenses. Among the common uropathogens associated to UTIs development, UroPathogenic Escherichia coli (UPEC) is the primary cause. UPEC strains possess a plethora of both structural (as fimbriae, pili, curli, flagella) and secreted (toxins, iron-acquisition systems) virulence factors that contribute to their capacity to cause disease, although the ability to adhere to host epithelial cells in the urinary tract represents the most important determinant of pathogenicity. On the opposite side, the bladder epithelium shows a multifaceted array of host defenses including the urine flow and the secretion of antimicrobial substances, which represent useful tools to counteract bacterial infections. The fascinating and intricate dynamics between these players determine a complex interaction system that needs to be revealed. This review will focus on the most relevant components of UPEC arsenal of pathogenicity together with the major host responses to infection, the current approved treatment and the emergence of resistant UPEC strains, the vaccine strategies, the natural antimicrobial compounds along with innovative anti-adhesive and prophylactic approaches to prevent UTIs. PMID:28861072

  16. Yersinia virulence factors - a sophisticated arsenal for combating host defences [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Steve Atkinson

    2016-06-01

    Full Text Available The human pathogens Yersinia pseudotuberculosis and Yersinia enterocolitica cause enterocolitis, while Yersinia pestis is responsible for pneumonic, bubonic, and septicaemic plague. All three share an infection strategy that relies on a virulence factor arsenal to enable them to enter, adhere to, and colonise the host while evading host defences to avoid untimely clearance. Their arsenal includes a number of adhesins that allow the invading pathogens to establish a foothold in the host and to adhere to specific tissues later during infection. When the host innate immune system has been activated, all three pathogens produce a structure analogous to a hypodermic needle. In conjunction with the translocon, which forms a pore in the host membrane, the channel that is formed enables the transfer of six ‘effector’ proteins into the host cell cytoplasm. These proteins mimic host cell proteins but are more efficient than their native counterparts at modifying the host cell cytoskeleton, triggering the host cell suicide response. Such a sophisticated arsenal ensures that yersiniae maintain the upper hand despite the best efforts of the host to counteract the infecting pathogen.

  17. The frequency of genes encoding three putative group B streptococcal virulence factors among invasive and colonizing isolates

    Directory of Open Access Journals (Sweden)

    Borchardt Stephanie M

    2006-07-01

    Full Text Available Abstract Background Group B Streptococcus (GBS causes severe infections in very young infants and invasive disease in pregnant women and adults with underlying medical conditions. GBS pathogenicity varies between and within serotypes, with considerable variation in genetic content between strains. Three proteins, Rib encoded by rib, and alpha and beta C proteins encoded by bca and bac, respectively, have been suggested as potential vaccine candidates for GBS. It is not known, however, whether these genes occur more frequently in invasive versus colonizing GBS strains. Methods We screened 162 invasive and 338 colonizing GBS strains from different collections using dot blot hybridization to assess the frequency of bca, bac and rib. All strains were defined by serotyping for capsular type, and frequency differences were tested using the Chi square test. Results Genes encoding the beta C protein (bac and Rib (rib occurred at similar frequencies among invasive and colonizing isolates, bac (20% vs. 23%, and rib (28% vs. 20%, while the alpha (bca C protein was more frequently found in colonizing strains (46% vs, invasive (29%. Invasive strains were associated with specific serotype/gene combinations. Conclusion Novel virulence factors must be identified to better understand GBS disease.

  18. The importance of Bordetella pertussis strains which do not produce virulence factors in the epidemiology of pertussis

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    Maciej Polak

    2017-05-01

    Full Text Available Bordetella pertussis strains, which have lost the ability to produce antigens, such as pertactin - Prn, pertussis toxin - Ptx, filamentous haemagglutinin - FHA, fimbriae type 2 and 3 - Fim 2 and 3, tracheal colonization factor - TcfA, have recently been isolated in countries with a high vaccination coverage. The emergence of such isolates might have resulted from B. pertussis natural evolution course or adaptive mechanisms, allowing increased circulation of the pathogen in vaccinated populations. So far, the majority of described mutants were deficient in the Prn production. Prn deficient isolates were found in countries which use acellular pertussis vaccines (aP in routine immunization programmes. The increase of frequency of Prn¯ strains isolation was correlated with the period of routine vaccination with aP vaccines. In most countries, the spread of these isolates has resulted from independent mutations rather than from the expansion of a single clone. Prn¯ isolates were collected from patients showing typical clinical symptoms of pertussis found for Prn+ strains. Results of in vitro and in vivo studies have shown that Prn¯, Ptx¯ and FHA¯ isolates retain cytotoxic properties, and besides Ptx¯ isolates, were lethal in intranasally infected mice. Further explanation of the impact of antigen deficiencies on virulence and transmission of B. pertussis in the context of the continuous increase of pertussis incidence is necessary to develop a new, optimized strategy of pertussis prevention.

  19. The zoonotic potential of Lactococcus garvieae: An overview on microbiology, epidemiology, virulence factors and relationship with its presence in foods.

    Science.gov (United States)

    Gibello, Alicia; Galán-Sánchez, Fátima; Blanco, M Mar; Rodríguez-Iglesias, Manuel; Domínguez, Lucas; Fernández-Garayzábal, José F

    2016-12-01

    Lactococcus garvieae is a relevant worldwide fish pathogen affecting various farmed and wild marine and freshwater species. It has also been isolated from other animals, such as ruminants with subclinical mastitis and pigs with pneumonia. From the early 90s, L. garvieae has been associated with different human infections, mainly endocarditis. During the last five years, human infections by this bacterium appear to be increasing, likely due to the improvement in microbiological methods for bacterial identification and the alertness of this bacterium by physicians. Human L. garvieae infections have been associated with the consumption or the handling of contaminated raw fish or seafood, and recently, a genetic study showed that meat, raw milk and dairy products may also be food sources of human L. garvieae infections. However, the status of L. garvieae as a potential zoonotic bacterium is still controversial to date. In this work, we describe four new human infections by L. garvieae in elderly and inmunocompromised patients, and we show an overview on L. garvieae microbiology, epidemiology, virulence factors and relationship with its presence in foods. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. The Ifchit1 chitinase gene acts as a critical virulence factor in the insect pathogenic fungus Isaria fumosorosea.

    Science.gov (United States)

    Huang, Zhen; Hao, Yongfen; Gao, Tianni; Huang, Yü; Ren, Shunxiang; Keyhani, Nemat O

    2016-06-01

    The filamentous fungus, Isaria fumosorosea, is a promising insect biological control agent. Chitinases have been implicated in targeting insect cuticle structures, with biotechnological potential in insect and fungal control. The I. fumosorosea chitinase gene, Ifchit1, was isolated and determined to encode a polypeptide of 423 amino acids (46 kDa, pI = 6.53), present as a single copy in the I. fumosorosea genome. A split marker transformation system was developed and used to construct an Ifchit1 gene knockout. The ΔIfchit1 strain displayed minor alterations in mycelial growth on diverse media at 26 °C compared to the wild type and complemented (ΔIfchit1::Ifchit1) strains; however, colony morphology was affected, and the mutant strain had a temperature sensitive phenotype (32 °C). Although sporulation was delayed for the mutant, overall conidial production was almost twice than that of wild type. Biochemical assays indicated decreased chitinase activity during growth in Czapek-Dox liquid media for the ΔIfchit1 strain. Insect bioassays using diamondback moth, Plutella xylostella, larvae revealed decreased infectivity, i.e., increased LC 50 (threefold to fourfold) and a significantly delayed time to death, LT 50 from 3 to 6 days, for the ΔIfchit1 strain compared to the wild type and complemented strains. These data indicate an important role for the Ifchit1 chitinase as a virulence factor in I. fumosorosea.

  1. Pseudomonas fluorescens filamentous hemagglutinin, an iron-regulated protein, is an important virulence factor that modulates bacterial pathogenicity

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    Yuan-yuan Sun

    2016-08-01

    Full Text Available Pseudomonas fluorescens is a common bacterial pathogen to a wide range of aquaculture animals including various species of fish. In this study, we employed proteomic analysis and identified filamentous hemagglutinin (FHA as an iron-responsive protein secreted by TSS, a pathogenic P. fluorescens isolate. In vitro study showed that compared to the wild type, the fha mutant TSSfha (i exhibited a largely similar vegetative growth profile but significantly retarded in the ability of biofilm growth and producing extracellular matrix, (ii displayed no apparent flagella and motility, (iii was defective in the attachment to host cells and unable to form self-aggregation, (iv displayed markedly reduced capacity of hemagglutination and surviving in host serum. In vivo infection analysis revealed that TSSfha was significantly attenuated in the ability of dissemination in fish tissues and inducing host mortality, and that antibody blocking of the natural FHA produced by the wild type TSS impaired the infectivity of the pathogen. Furthermore, when introduced into turbot as a subunit vaccine, recombinant FHA elicited a significant protection against lethal TSS challenge. Taken together, these results indicate for the first time that P. fluorescens FHA is a key virulence factor essential to multiple biological processes associated with pathogenicity.

  2. Differential Growth of Francisella tularensis, Which Alters Expression of Virulence Factors, Dominant Antigens, and Surface-Carbohydrate Synthases, Governs the Apparent Virulence of Ft SchuS4 to Immunized Animals

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    Kristen M. Holland

    2017-06-01

    Full Text Available The gram-negative bacterium Francisella tularensis (Ft is both a potential biological weapon and a naturally occurring microbe that survives in arthropods, fresh water amoeba, and mammals with distinct phenotypes in various environments. Previously, we used a number of measurements to characterize Ft grown in Brain-Heart Infusion (BHI broth as (1 more similar to infection-derived bacteria, and (2 slightly more virulent in naïve animals, compared to Ft grown in Mueller Hinton Broth (MHB. In these studies we observed that the free amino acids in MHB repress expression of select Ft virulence factors by an unknown mechanism. Here, we tested the hypotheses that Ft grown in BHI (BHI-Ft accurately displays a full protein composition more similar to that reported for infection-derived Ft and that this similarity would make BHI-Ft more susceptible to pre-existing, vaccine-induced immunity than MHB-Ft. We performed comprehensive proteomic analysis of Ft grown in MHB, BHI, and BHI supplemented with casamino acids (BCA and compared our findings to published “omics” data derived from Ft grown in vivo. Based on the abundance of ~1,000 proteins, the fingerprint of BHI-Ft is one of nutrient-deprived bacteria that—through induction of a stringent-starvation-like response—have induced the FevR regulon for expression of the bacterium's virulence factors, immuno-dominant antigens, and surface-carbohydrate synthases. To test the notion that increased abundance of dominant antigens expressed by BHI-Ft would render these bacteria more susceptible to pre-existing, vaccine-induced immunity, we employed a battery of LVS-vaccination and S4-challenge protocols using MHB- and BHI-grown Ft S4. Contrary to our hypothesis, these experiments reveal that LVS-immunization provides a barrier to infection that is significantly more effective against an MHB-S4 challenge than a BHI-S4 challenge. The differences in apparent virulence to immunized mice are profoundly greater

  3. Fis is a global regulator critical for modulation of virulence factor production and pathogenicity of Dickeya zeae.

    Science.gov (United States)

    Lv, Mingfa; Chen, Yufan; Liao, Lisheng; Liang, Zhibin; Shi, Zurong; Tang, Yingxin; Ye, Sixuan; Zhou, Jianuan; Zhang, Lianhui

    2018-01-10

    Dickeya zeae is the causal agent of rice foot rot disease, which has recently become a great threat to rice planting countries and regions. The pathogen produces a family of phytotoxins named zeamines that is critical for bacterial virulence, but little is known about the signaling pathways and regulatory mechanisms that govern zeamine production. In this study, we showed that a conserved transcriptional regulator Fis is involved in the regulation of zeamine production in D. zeae strain EC1. Deletion mutants were markedly attenuated in the virulence against rice seed germination. Transcriptome and phenotype analyses showed that Fis is a potent global transcriptional regulator modulating various virulence traits, including production of extracellular enzymes and exopolysaccharides, swimming and swarming motility, biofilm formation and cell aggregation. DNA gel retardation analysis showed that Fis directly regulates the transcription of key virulence genes and the genes encoding Vfm quorum sensing system through DNA/protein interaction. Our findings unveil a key regulator associated with the virulence of D. zeae EC1, and present useful clues for further elucidation of the regulatory complex and signaling pathways which govern the virulence of this important pathogen.

  4. Growth conditions and environmental factors impact aerosolization but not virulence of Francisella tularensis infection in mice.

    Directory of Open Access Journals (Sweden)

    Seth eFaith

    2012-10-01

    Full Text Available In refining methodology to develop a mouse model for inhalation of Francisella tularensis, it was noted that both relative humidity and growth media impacted the aerosol concentration of the live vaccine strain (LVS of F. tularensis. A relative humidity of less than 55% had a negative impact on the spray factor, the ratio between the concentration of LVS in the aerosol and the nebulizer. The spray factor was significantly higher for LVS grown in brain heart infusion (BHI broth than LVS grown in Mueller-Hinton broth (MHb or Chamberlain’s Chemically Defined Medium (CCDM. The variability between aerosol exposures was also considerably less with BHI. LVS grown in BHI survived desiccation far longer than MHb-grown or CCDM-grown LVS (~70% at 20 minutes for BHI compared to <50% for MHb and CCDM. Removal of the capsule by hypertonic treatment impacted the spray factor for CCDM-grown LVS or MHb-grown LVS but not BHI-grown LVS, suggesting the choice of culture media altered the adherence of the capsule to the cell membrane. The choice of growth media did not impact the LD50 of LVS but the LD99 of BHI-grown LVS was 1 log lower than that for MHb-grown LVS or CCDM-grown LVS. Splenomegaly was prominent in mice that succumbed to MHb- and BHI-grown LVS but not CCDM-grown LVS. Environmental factors and growth conditions should be evaluated when developing new animal models for aerosol infection, particularly for vegetative bacterial pathogens.

  5. Molecular characteristics and virulence factors in methicillin-susceptible, resistant, and heterogeneous vancomycin-intermediate Staphylococcus aureus from central-southern China.

    Science.gov (United States)

    Liu, Cailin; Chen, Zhong-ju; Sun, Ziyong; Feng, Xianju; Zou, Mingxiang; Cao, Wei; Wang, Shanmei; Zeng, Ji; Wang, Yue; Sun, Mingyue

    2015-10-01

    Staphylococcus aureus is a leading cause of nosocomial infections. The purpose of this study was to evaluate the prevalence of methicillin-resistant S. aureus (MRSA) and heterogeneous vancomycin-intermediate S. aureus (hVISA), and compare the antimicrobial susceptibility, molecular characteristic, and virulence factors in methicillin-susceptible S. aureus (MSSA), MRSA, and hVISA from central-southern China. A total of 184 S. aureus were isolated from sterile body fluids. All isolates were subjected to population analysis profiling for the identification of hVISA phenotype and polymerase chain reaction analysis for genotyping and 31 virulence genes. The prevalence of MRSA isolates was 41.8% in central-southern China. Of 77 MRSA isolates, 17 (22.1%) were identified as hVISA. The most common MRSA and MSSA clones were ST239-MRSA-SCCmecIII-t030-agr-I (55.8%) and ST188-MSSA-t189-agr-I (20.6%), respectively. The frequency of carriage of pvl, hemolysins, tst, and staphylococcal enterotoxin genes among MSSA isolates was significantly higher than that for MRSA isolates (p aureus isolates; the virulence genes were more diverse and frequent among MSSA isolates than among MRSA isolates. Furthermore, the distribution of some virulence genes was correlated with the different S. aureus CCs. Copyright © 2014. Published by Elsevier B.V.

  6. Factors associated with virulence and survival in environmental and clinical isolates of Vibrio cholerae O1 and non O1 in Romania.

    Science.gov (United States)

    Israil, Anca; Balotescu, Carmen; Bucurenci, Nadia; Năcescu, Nadia; Cedru, Claudia; Popa, Cornelia; Ciufecu, C

    2003-01-01

    Four hundred ninety seven strains of Vibrio cholerae selected from isolates in Romania in the last decade 1990-1999 were investigated for antibiotic resistance and for classical and putative virulence factors. V. cholerae O1 strains predominated in clinical cases and non O1 strains in the environment, excepting in 1992 when non O1 strains were frequent in clinical and environmental sources. V. cholerae O1 strains previously susceptible to tetracycline acquired clinically significant resistance to this drug during 1993-1994, but this trend was reversed in 1995, following the introduction of nalidixic acid in cholera treatment in 1994. V. cholerae O1 and non O1 clinical isolates acquired simultaneous resistance to the vibriostatic agent O/129 and cotrimoxazole during 1994-1995. High levels of intrinsic resistance to multiple antibiotics were exhibited by all strains examined. The presence of cholera toxin (CT) was concentrated in clinical V. cholerae O1 strains and was substituted in clinical non O1 strains by four putative virulence markers (Kanagawa haemolysin, slime, lipase, and colonial opacity). Colonial opacity (30%) was present only in clinical isolates of V. cholerae non O1. Pigmentogenesis (11.7%) has present only in environmental sources. Antibioresistance profiles differ for V. cholerae O1 and non O1 strains with respect to their source of isolation. This aspect may imply a role in virulence and survival of V. cholerae in the natural environment where they may serve as a reservoir of virulence and multiple drug resistance genes.

  7. Inflammatory Bowel Disease Associated with Virulence Factors in Escherichia coli

    DEFF Research Database (Denmark)

    Mirsepasi-Lauridsen, Hengameh

    and influence of the gastrointestinal microbiota. The gut microbiota of IBD patients contributes to initiation and/ or maintaining the inflammatory state by providing antigens or co-stimulatory factors that drive the immune response in a misdirection in these genetically susceptible hosts. Alterations...... in the makeup of the intestinal microbiota in IBD patients include a reduced diversity of intestinal microbial species in comparison to healthy controls, which is linked to the pathogenesis of IBD (Manuscript I). In addition, we showed that highest amount of DNA from the stool was extracted using manual Qiagen...

  8. Virulence factor rtx in Legionella pneumophila, evidence suggesting it is a modular multifunctional protein

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    Pelaz Carmen

    2008-01-01

    Full Text Available Abstract Background The repeats in toxin (Rtx are an important pathogenicity factor involved in host cells invasion of Legionella pneumophila and other pathogenic bacteria. Its role in escaping the host immune system and cytotoxic activity is well known. Its repeated motives and modularity make Rtx a multifunctional factor in pathogenicity. Results The comparative analysis of rtx gene among 6 strains of L. pneumophila showed modularity in their structures. Among compared genomes, the N-terminal region of the protein presents highly dissimilar repeats with functionally similar domains. On the contrary, the C-terminal region is maintained with a fashionable modular configuration, which gives support to its proposed role in adhesion and pore formation. Despite the variability of rtx among the considered strains, the flanking genes are maintained in synteny and similarity. Conclusion In contrast to the extracellular bacteria Vibrio cholerae, in which the rtx gene is highly conserved and flanking genes have lost synteny and similarity, the gene region coding for the Rtx toxin in the intracellular pathogen L. pneumophila shows a rapid evolution. Changes in the rtx could play a role in pathogenicity. The interplay of the Rtx toxin with host membranes might lead to the evolution of new variants that are able to escape host cell defences.

  9. Anaerobes and Bacterial Vaginosis in Pregnancy: Virulence Factors Contributing to Vaginal Colonisation

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    Charlene W. J. Africa

    2014-07-01

    Full Text Available The aetiology and pathogenesis of bacterial vaginosis (BV is unclear but it appears to be associated with factors that disrupt the normal acidity of the vagina thus altering the equilibrium between the normal vaginal microbiota. BV has serious implications for female morbidity, including reports of pelvic inflammatory disease, adverse pregnancy outcomes, increased susceptibility to sexually transmitted infections and infertility. This paper reviewed new available information regarding possible factors contributing to the establishment of the BV vaginal biofilm, examined the proposed role of anaerobic microbial species recently detected by new culture-independent methods and discusses developments related to the effects of BV on human pregnancy. The literature search included Pubmed (NLM, LISTA (EBSCO, and Web of Science. Because of the complexity and diversity of population groups, diagnosis and methodology used, no meta-analysis was performed. Several anaerobic microbial species previously missed in the laboratory diagnosis of BV have been revealed while taking cognisance of newly proposed theories of infection, thereby improving our understanding and knowledge of the complex aetiology and pathogenesis of BV and its perceived role in adverse pregnancy outcomes.

  10. Cloning, expression, purification and crystallization of a pair of novel virulence factors, SghA and SghR, from Agrobacterium tumefaciens

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Fuzhou [Nanyang Technological University, 60 Nanyang Drive, Singapore 637551 (Singapore); Wang, Chao [Institute of Molecular and Cell Biology, 61 Biopolis Drive, Singapore 138673 (Singapore); National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610 (Singapore); Fu, Qinqin [Nanyang Technological University, 60 Nanyang Drive, Singapore 637551 (Singapore); Zhang, Lian-hui [Institute of Molecular and Cell Biology, 61 Biopolis Drive, Singapore 138673 (Singapore); Gao, Yong-gui, E-mail: ygao@ntu.edu.sg [Nanyang Technological University, 60 Nanyang Drive, Singapore 637551 (Singapore); Institute of Molecular and Cell Biology, 61 Biopolis Drive, Singapore 138673 (Singapore)

    2015-08-25

    The crystallization of the novel virulence factors SghA and SghR is reported. Two proteins, SghA and SghR, which were recently identified and characterized as novel bacterial virulence factors regulating the infection of plant hosts by Agrobacterium, were cloned, overexpressed and purified with high yield. Both SghA and SghR form dimers in solution. The purified SghA and SghR were crystallized and the crystals diffracted to 1.9 and 2.1 Å resolution, respectively. Data were collected and processed, and the crystallographic parameters were within acceptable ranges. These results will help in the determination of their structures in order to uncover the molecular mechanism of how these two proteins together control the release of plant defence signals against agrobacteria during pathogen–host interaction.

  11. Pore-forming virulence factors of Staphylococcus aureus destabilize epithelial barriers-effects of alpha-toxin in the early phases of airway infection

    Directory of Open Access Journals (Sweden)

    Jan-Peter Hildebrandt

    2015-09-01

    Full Text Available Staphylococcus aureus (S. aureus is a human commensal and an opportunistic pathogen that may affect the gastrointestinal tract, the heart, bones, skin or the respiratory tract. S. aureus is frequently involved in hospital- or community-acquired lung infections. The pathogenic potential is associated with its ability to secrete highly effective virulence factors. Among these, the pore-forming toxins Panton-Valentine leukocidin (PVL and hemolysin A (Hla are the important virulence factors determining the prognosis of pneumonia cases. This review focuses on the structure and the functions of S. aureus hemolysin A and its sub-lethal effects on airway epithelial cells. The hypothesis is developed that Hla may not just be a tissue-destructive agent providing the bacteria with host-derived nutrients, but may also play complex roles in the very early stages of interactions of bacteria with healthy airways, possibly paving the way for establishing acute infections.

  12. Virulence factors and resistance to antimicrobials in Listeria monocytogenes serotype 1/2c isolated from food.

    Science.gov (United States)

    Gelbíčová, T; Pantůček, R; Karpíšková, R

    2016-08-01

    The aim of this study was to assess the potential risk posed to the human population by the presence of Listeria monocytogenes serotype 1/2c in food based on the characterization of virulence factors of Listeria involved in the invasion of host cells and sensitivity to antimicrobial agents. In addition to sequencing of the inlA and inlB genes, the presence of genes lapB, aut, fbpA, ami, vip and llsX was tested. A premature stop codon (PMSC) in the inlA gene was detected in all tested strains of serotype 1/2c and, concurrently, two novel PMSC mutation types were identified. However, neither PMSC in the inlB gene nor deletion of the lapB, aut, fbpA, ami and vip genes were found in any of the strains. The presence of the llsX gene was not confirmed. Even though all L. monocytogenes strains showed sensitivity to the tested antimicrobials on the basis of their phenotype, sequencing revealed the presence of IS1542 insertion in the inlA gene, indicating the possibility of sharing of mobile genetic elements associated with antimicrobial resistance among strains. Other than the presence of PMSCs in the inlA gene, no PMSC in inlB or deletion of other factors linked to the invasiveness of listeria were detected. Tested strains showed sensitivity to antibiotics used in the therapy of listeriosis. Strains of L. monocytogenes serotype 1/2c typically carry a PMSC in the inlA gene, but these strains still represent a potential threat to public health. The possibility of transfer of IS1542, associated with resistance to vancomycin, between enterococci and Listeria spp. was revealed. © 2016 The Society for Applied Microbiology.

  13. H. pylori virulence factor CagA increases intestinal cell proliferation by Wnt pathway activation in a transgenic zebrafish model

    Directory of Open Access Journals (Sweden)

    James T. Neal

    2013-05-01

    Infection with Helicobacter pylori is a major risk factor for the development of gastric cancer, and infection with strains carrying the virulence factor CagA significantly increases this risk. To investigate the mechanisms by which CagA promotes carcinogenesis, we generated transgenic zebrafish expressing CagA ubiquitously or in the anterior intestine. Transgenic zebrafish expressing either the wild-type or a phosphorylation-resistant form of CagA exhibited significantly increased rates of intestinal epithelial cell proliferation and showed significant upregulation of the Wnt target genes cyclinD1, axin2 and the zebrafish c-myc ortholog myca. Coexpression of CagA with a loss-of-function allele encoding the β-catenin destruction complex protein Axin1 resulted in a further increase in intestinal proliferation. Coexpression of CagA with a null allele of the key β-catenin transcriptional cofactor Tcf4 restored intestinal proliferation to wild-type levels. These results provide in vivo evidence of Wnt pathway activation by CagA downstream of or in parallel to the β-catenin destruction complex and upstream of Tcf4. Long-term transgenic expression of wild-type CagA, but not the phosphorylation-resistant form, resulted in significant hyperplasia of the adult intestinal epithelium. We further utilized this model to demonstrate that oncogenic cooperation between CagA and a loss-of-function allele of p53 is sufficient to induce high rates of intestinal small cell carcinoma and adenocarcinoma, establishing the utility of our transgenic zebrafish model in the study of CagA-associated gastrointestinal cancers.

  14. Variation in the cytoadherence characteristics of malaria parasites: is this a true virulence factor?

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    J. D. Goldring

    1992-01-01

    Full Text Available The sequestration of Plasmodium falciparum-infected erythrocytes to the endothelial cells of brain capillaries is believed to represent one of the determining factors in the pathogenesis of cerebral malaria. In vitro studies of cytoadherence provide an experimental approach to understand the mechanism of sequestration and the respective roles played by parasite and host components in this interaction. This paper critically reviews current studies on cytoadherence, with particular emphasis on the nature of the information provided by such studies and their limitations. The paper also describes how cytoadherence studies using the patient's own monocytes can provide original information on the level of receptor up-regulation in the course of malarial infection.

  15. Peroxisome biogenesis in mammalian cells

    Directory of Open Access Journals (Sweden)

    Yukio eFujiki

    2014-08-01

    Full Text Available To investigate peroxisome assembly and human peroxisome biogenesis disorders (PBDs such as Zellweger syndrome, thirteen different complementation groups (CGs of Chinese hamster ovary (CHO cell mutants defective in peroxisome biogenesis have been isolated and established as a model research system. Successful gene-cloning studies by a forward genetic approach utilized a rapid functional complementation assay of CHO cell mutants led to isolation of human peroxide (PEX genes. Search for pathogenic genes responsible for PBDs of all 14 CGs is now completed together with the homology search by screening the human expressed sequence tag database using yeast PEX genes. Peroxins are divided into three groups: (1 peroxins including Pex3p, Pex16p and Pex19p, are responsible for peroxisome membrane biogenesis via classes I and II pathways; (2 peroxins that function in matrix protein import; (3 those such as three forms of Pex11p, Pex11pα, Pex11pβ, and Pex11pγ, are involved in peroxisome proliferation where DLP1, Mff, and Fis1 coordinately function. In membrane assembly, Pex19p forms complexes in the cytosol with newly synthesized PMPs including Pex16p and transports them to the receptor Pex3p, whereby peroxisomal membrane is formed (Class I pathway. Pex19p likewise forms a complex with newly made Pex3p and translocates it to the Pex3p receptor, Pex16p (Class II pathway. In matrix protein import, newly synthesized proteins harboring peroxisome targeting signal type 1 or 2 are recognized by Pex5p or Pex7p in the cytoplasm and are imported to peroxisomes via translocation machinery. In regard to peroxisome-cytoplasmic shuttling of Pex5p, Pex5p initially targets to an 800-kDa docking complex consisting of Pex14p and Pex13p and then translocates to a 500-kDa RING translocation complex. At the terminal step, Pex1p and Pex6p of the AAA family mediate the export of Pex5p, where Cys-ubiquitination of Pex5p is essential for the Pex5p exit.

  16. Inhibition of quorum sensing-controlled virulence factors and biofilm formation in Pseudomonas fluorescens by cinnamaldehyde.

    Science.gov (United States)

    Li, Tingting; Wang, Dangfeng; Liu, Nan; Ma, Yan; Ding, Ting; Mei, Yongchao; Li, Jianrong

    2018-02-01

    Pseudomonas fluorescens, an important food spoiling bacteria, uses quorum sensing to control biofilm formation and motility. To date, only a few compounds targeting the LuxR-based quorum sensing system of P. fluorescens have been identified. In the present study, the quorum sensing inhibitory effect of cinnamaldehyde at sublethal concentrations was investigated in terms of inhibition of the extracellular protease, biofilm formation, and swimming and swarming motility. The total volatile basic nitrogen value was also measured to evaluate the effect of cinnamaldehyde on quality preservation of turbot fillets stored at 4 ± 1 °C for 15 days. The results showed that cinnamaldehyde significantly inhibited quorum sensing-dependent factors in P. fluorescens and extended the storage life of turbot. Unexpectedly, cinnamaldehyde did not interfere with production of AHLs (N-acylhomoserine lactones) by P. fluorescens, as shown by measurement of AHL production using GC-MS. Molecular docking analysis revealed that cinnamaldehyde can interact with the LuxR-type protein of P. fluorescens, which could constitute the molecular basis of the quorum sensing inhibition observed. These findings strongly suggest that cinnamaldehyde is a quorum sensing inhibitor with great potential for the preservation of aquatic products to guarantee food safety. Copyright © 2018. Published by Elsevier B.V.

  17. Evaluation of virulence factors of Candida albicans isolated from HIV-positive individuals using HAART.

    Science.gov (United States)

    de Paula Menezes, Ralciane; de Melo Riceto, Érika Bezerra; Borges, Aércio Sebastião; de Brito Röder, Denise Von Dolingër; dos Santos Pedroso, Reginaldo

    2016-06-01

    The colonization by Candida species is one of the most important factors related to the development of oral candidiasis in HIV-infected individuals. The aim of the study was to evaluate and discuss the phospholipase, proteinase, DNAse and haemolytic activities of Candida albicans isolated from the oral cavity of HIV individuals with high efficiency antiretroviral therapy. Seventy-five isolates of C. albicans obtained from saliva samples of patients with HIV and 41 isolates from HIV-negative individuals were studied. Haemolytic activity was determined in Sabouraud dextrose agar plates containing 3% glucose and 7% sheep red cells. Culture medium containing DNA base-agar, egg yolk, and bovine albumin were used to determine DNase, phospholipase and proteinase activities, respectively. All isolates from the HIV patients group had haemolytic activity, 98% showed phospholipase activity, 92% were positive for proteinase and 32% DNAse activity. Regarding the group of indivídios HIV negative, all 41 isolates presented hemolytic activity, 90.2% showed phospholipase and proteinase activity and 12.2% were positive for DNAse. The phospholipase activity was more intense for the group of HIV positive individuals. DNase production was more frequently observed in the group of HIV-positive individuals. The percentage of isolates having DNAse activity was also significantly different between the groups of patients not using any antiretroviral therapy, those using transcriptase inhibitors and those using transcriptase inhibitor and protease inhibitor in combination. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Signature Motifs Identify an Acinetobacter Cif Virulence Factor with Epoxide Hydrolase Activity*

    Science.gov (United States)

    Bahl, Christopher D.; Hvorecny, Kelli L.; Bridges, Andrew A.; Ballok, Alicia E.; Bomberger, Jennifer M.; Cady, Kyle C.; O'Toole, George A.; Madden, Dean R.

    2014-01-01

    Endocytic recycling of the cystic fibrosis transmembrane conductance regulator (CFTR) is blocked by the CFTR inhibitory factor (Cif). Originally discovered in Pseudomonas aeruginosa, Cif is a secreted epoxide hydrolase that is transcriptionally regulated by CifR, an epoxide-sensitive repressor. In this report, we investigate a homologous protein found in strains of the emerging nosocomial pathogens Acinetobacter nosocomialis and Acinetobacter baumannii (“aCif”). Like Cif, aCif is an epoxide hydrolase that carries an N-terminal secretion signal and can be purified from culture supernatants. When applied directly to polarized airway epithelial cells, mature aCif triggers a reduction in CFTR abundance at the apical membrane. Biochemical and crystallographic studies reveal a dimeric assembly with a stereochemically conserved active site, confirming our motif-based identification of candidate Cif-like pathogenic EH sequences. Furthermore, cif expression is transcriptionally repressed by a CifR homolog (“aCifR”) and is induced in the presence of epoxides. Overall, this Acinetobacter protein recapitulates the essential attributes of the Pseudomonas Cif system and thus may facilitate airway colonization in nosocomial lung infections. PMID:24474692

  19. Signature motifs identify an Acinetobacter Cif virulence factor with epoxide hydrolase activity.

    Science.gov (United States)

    Bahl, Christopher D; Hvorecny, Kelli L; Bridges, Andrew A; Ballok, Alicia E; Bomberger, Jennifer M; Cady, Kyle C; O'Toole, George A; Madden, Dean R

    2014-03-14

    Endocytic recycling of the cystic fibrosis transmembrane conductance regulator (CFTR) is blocked by the CFTR inhibitory factor (Cif). Originally discovered in Pseudomonas aeruginosa, Cif is a secreted epoxide hydrolase that is transcriptionally regulated by CifR, an epoxide-sensitive repressor. In this report, we investigate a homologous protein found in strains of the emerging nosocomial pathogens Acinetobacter nosocomialis and Acinetobacter baumannii ("aCif"). Like Cif, aCif is an epoxide hydrolase that carries an N-terminal secretion signal and can be purified from culture supernatants. When applied directly to polarized airway epithelial cells, mature aCif triggers a reduction in CFTR abundance at the apical membrane. Biochemical and crystallographic studies reveal a dimeric assembly with a stereochemically conserved active site, confirming our motif-based identification of candidate Cif-like pathogenic EH sequences. Furthermore, cif expression is transcriptionally repressed by a CifR homolog ("aCifR") and is induced in the presence of epoxides. Overall, this Acinetobacter protein recapitulates the essential attributes of the Pseudomonas Cif system and thus may facilitate airway colonization in nosocomial lung infections.

  20. Rapid screening of pyogenic Staphylococcus aureus for confirmation of genus and species, methicillin resistance and virulence factors by using two novel multiplex PCR.

    Science.gov (United States)

    Haque, Abdul; Haque, Asma; Saeed, Muhammad; Azhar, Aysha; Rasool, Samreen; Shan, Sidra; Ehsan, Beenish; Nisar, Zohaib

    2017-01-01

    Emergence of methicillin resistant Staphylococcus aureus (MRSA) is a major medical problem of current era. These bacteria are resistant to most drugs and rapid diagnosis can provide a clear guideline to clinicians. They possess specific virulence factors and relevant information can be very useful. We designed this study to develop multiplex PCRs to provide rapid information. We studied 60 Staphylococcus aureus isolates and detected methicillin resistance by cefoxitin sensitivity and targeting of mecA gene. After initial studies with uniplex PCRs we optimized two multiplex PCRs with highly reproducible results. The first multiplex PCR was developed to confirm genus, species and methicillin resistance simultaneously, and the second multiplex PCR was for screening of virulence factors. We found 38.33% isolates as methicillin resistant. α -toxin, the major cytotoxic factor, was detected in 40% whereas β-hemolysin was found in 25% cases. Panton Valentine leucocidin was detected in 8.33% and toxic shock syndrome toxin in5% cases. The results of uniplex and multiplex PCRs were highly compatible. These two multiplex PCRs when run simultaneously can provide vital information about methicillin resistance and virulence status of the isolate within a few hours as compared to several days needed by routine procedures.

  1. Phenotypic switching and its influence on expression of virulence factors by Candida albicans causing candidiasis in human immunodeficiency virus-infected patients

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    Antony G

    2007-01-01

    Full Text Available Purpose : The purpose of the present study was to determine the degree of expression of virulence factors such as adherence, cell surface hydrophobicity (CSH and production of proteinase by different morphological forms of Candida albicans causing oral candidiasis in human immunodeficiency virus (HIV-infected individuals. Methods : C. albicans 3153A and two strains isolated from oral thrush in HIV infected individuals were induced to undergo phenotypic switching by exposure to UV light and the degree of expression of virulence factors by the different morphological forms was studied. Results : Three different morphological forms of C. albicans were obtained namely, star (S, wrinkled (W and ring (R types from the original smooth (O variety. It was found that proteinase production was greatest with the W type followed by the R type and O type. The S type produced the least proteinase. Expression of cell surface hydrophobicity and adherence was greatest in the O type followed by the R and then the W type and finally the S type. Conclusions : The differential expression of virulence factors occurs with different phenotypic forms of C. albicans and this may provide a particular morphological type with a distinct advantage over other types in causing candidiasis.

  2. Global effect of indole-3-acetic acid biosynthesis on multiple virulence factors of Erwinia chrysanthemi 3937.

    Science.gov (United States)

    Yang, Shihui; Zhang, Qiu; Guo, Jianhua; Charkowski, Amy O; Glick, Bernard R; Ibekwe, A Mark; Cooksey, Donald A; Yang, Ching-Hong

    2007-02-01

    Production of the plant hormone indole-3-acetic acid (IAA) is widespread among plant-associated microorganisms. The non-gall-forming phytopathogen Erwinia chrysanthemi 3937 (strain Ech3937) possesses iaaM (ASAP16562) and iaaH (ASAP16563) gene homologues. In this work, the null knockout iaaM mutant strain Ech138 was constructed. The IAA production by Ech138 was reduced in M9 minimal medium supplemented with l-tryptophan. Compared with wild-type Ech3937, Ech138 exhibited reduced ability to produce local maceration, but its multiplication in Saintpaulia ionantha was unaffected. The pectate lyase production of Ech138 was diminished. Compared with wild-type Ech3937, the expression levels of an oligogalacturonate lyase gene, ogl, and three endopectate lyase genes, pelD, pelI, and pelL, were reduced in Ech138 as determined by a green fluorescent protein-based fluorescence-activated cell sorting promoter activity assay. In addition, the transcription of type III secretion system (T3SS) genes, dspE (a putative T3SS effector) and hrpN (T3SS harpin), was found to be diminished in the iaaM mutant Ech138. Compared with Ech3937, reduced expression of hrpL (a T3SS alternative sigma factor) and gacA but increased expression of rsmA in Ech138 was also observed, suggesting that the regulation of T3SS and pectate lyase genes by IAA biosynthesis might be partially due to the posttranscriptional regulation of the Gac-Rsm regulatory pathway.

  3. Rare emergence of symptoms during long-term asymptomatic Escherichia coli 83972 carriage without an altered virulence factor repertoire.

    Science.gov (United States)

    Köves, Béla; Salvador, Ellaine; Grönberg-Hernández, Jenny; Zdziarski, Jaroslaw; Wullt, Björn; Svanborg, Catharina; Dobrindt, Ulrich

    2014-02-01

    Asymptomatic bacteriuria established by intravesical inoculation of Escherichia coli 83972 is protective in patients with recurrent urinary tract infections. In this randomized, controlled crossover study a total of 3 symptomatic urinary tract infection episodes developed in 2 patients while they carried E. coli 83972. We examined whether virulence reacquisition by symptom isolates may account for the switch from asymptomatic bacteriuria to symptomatic urinary tract infection. We used E. coli 83972 re-isolates from 2 patients in a prospective study and from another 2 in whom symptoms developed after study completion. We phylogenetically classified the re-isolates, and identified the genomic restriction patterns and gene expression profiles as well as virulence gene structure and phenotypes. In vivo virulence was examined in the murine urinary tract infection model. The fim, pap, foc, hlyA, fyuA, iuc, iroN, kpsMT K5 and malX genotypes of the symptomatic re-isolates remained unchanged. Bacterial gene expression profiles of flagellated symptomatic re-isolates were unique to each host, providing no evidence of common deregulation. Symptomatic isolates did not differ in virulence from the wild-type strain, as defined in the murine urinary tract infection model by persistence, symptoms or innate immune activation. The switch from asymptomatic E. coli 83972 carriage to symptomatic urinary tract infection was not explained by reversion to a functional virulence gene repertoire. Copyright © 2014 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  4. Enterococcus faecalis from Food, Clinical Specimens, and Oral Sites: Prevalence of Virulence Factors in Association with Biofilm Formation

    Science.gov (United States)

    Anderson, Annette C.; Jonas, Daniel; Huber, Ingrid; Karygianni, Lamprini; Wölber, Johan; Hellwig, Elmar; Arweiler, Nicole; Vach, Kirstin; Wittmer, Annette; Al-Ahmad, Ali

    2016-01-01

    Enterococci have gained significance as the cause of nosocomial infections; they occur as food contaminants and have also been linked to dental diseases. E. faecalis has a great potential to spread virulence as well as antibiotic resistance genes via horizontal gene transfer. The integration of food-borne enterococci into the oral biofilm in-vivo has been observed. Therefore, we investigated the virulence determinants and antibiotic resistance of 97 E. faecalis isolates from the oral cavity, food, and clinical specimens. In addition, phenotypic expression of gelatinase and cytolysin were tested, in-vitro biofilm formation was quantified and isolates were compared for strain relatedness via pulsed field gel electrophoresis (PFGE). Each isolate was found to possess two or more virulence genes, most frequently gelE, efaA, and asa1. Notably, plaque/saliva isolates possessed the highest abundance of virulence genes, the highest levels of phenotypic gelatinase and hemolysin activity and concurrently a high ability to form biofilm. The presence of asa1 was associated with biofilm formation. The biofilm formation capacity of clinical and plaque/saliva isolates was considerably higher than that of food isolates and they also showed similar antibiotic resistance patterns. These results indicate that the oral cavity can constitute a reservoir for virulent E. faecalis strains possessing antibiotic resistance traits and at the same time distinct biofilm formation capabilities facilitating exchange of genetic material. PMID:26793174

  5. Biogenesis of light harvesting proteins.

    Science.gov (United States)

    Dall'Osto, Luca; Bressan, Mauro; Bassi, Roberto

    2015-09-01

    The LHC family includes nuclear-encoded, integral thylakoid membrane proteins, most of which coordinate chlorophyll and xanthophyll chromophores. By assembling with the core complexes of both photosystems, LHCs form a flexible peripheral moiety for enhancing light-harvesting cross-section, regulating its efficiency and providing protection against photo-oxidative stress. Upon its first appearance, LHC proteins underwent evolutionary diversification into a large protein family with a complex genetic redundancy. Such differentiation appears as a crucial event in the adaptation of photosynthetic organisms to changing environmental conditions and land colonization. The structure of photosystems, including nuclear- and chloroplast-encoded subunits, presented the cell with a number of challenges for the control of the light harvesting function. Indeed, LHC-encoding messages are translated in the cytosol, and pre-proteins imported into the chloroplast, processed to their mature size and targeted to the thylakoids where are assembled with chromophores. Thus, a tight coordination between nuclear and plastid gene expression, in response to environmental stimuli, is required to adjust LHC composition during photoacclimation. In recent years, remarkable progress has been achieved in elucidating structure, function and regulatory pathways involving LHCs; however, a number of molecular details still await elucidation. In this review, we will provide an overview on the current knowledge on LHC biogenesis, ranging from organization of pigment-protein complexes to the modulation of gene expression, import and targeting to the photosynthetic membranes, and regulation of LHC assembly and turnover. Genes controlling these events are potential candidate for biotechnological applications aimed at optimizing light use efficiency of photosynthetic organisms. This article is part of a Special Issue entitled: Chloroplast biogenesis. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Comparative transcriptomic analysis of virulence factors in Leptosphaeria maculans during compatible and incompatible interactions with canola

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    Humira Sonah

    2016-12-01

    Full Text Available Leptosphaeria maculans is a hemibiotrophic fungus that causes blackleg of canola (Brassica napus, one of the most devastating diseases of this crop. In the present study, transcriptome profiling of L. maculans was performed in an effort to understand and define the pathogenicity genes that govern both the biotrophic and the necrotrophic phase of the fungus, as well as those that separate a compatible from an incompatible interaction. For this purpose, comparative RNA-seq analyses were performed on L. maculans isolate D5 at four different time points following inoculation on susceptible cultivar Topas-wild or resistant near isogenic line Topas-Rlm2. Analysis of 1.6 billion Illumina reads readily identified differentially expressed genes that were over represented by candidate secretory effector proteins, CAZymes, and other pathogenicity genes. Comparisons between the compatible and incompatible interactions led to the identification of 28 effector proteins whose chronology and level of expression suggested a role in the establishment and maintenance of biotrophy with the plant. These included all known Avr genes of isolate D5 along with eight newly characterized effectors. In addition, another 15 effector proteins were found to be exclusively expressed during the necrotrophic phase of the fungus, which supports the concept that L. maculans has a separate and distinct arsenal contributing to each phase. As for CAZymes, they were often highly expressed at 3 dpi but with no difference in expression between the compatible and incompatible interactions, indicating that other factors were necessary to determine the outcome of the interaction. However, their significantly higher expression at 11 dpi in the compatible interaction confirmed that they contributed to the necrotrophic phase of the fungus. A notable exception was LysM genes whose high expression was singularly observed on the susceptible host at 7 dpi. In the case of TFs, their higher

  7. Proteomic analysis of growth phase-dependent expression of Legionella pneumophila proteins which involves regulation of bacterial virulence traits.

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    Tsuyoshi Hayashi

    Full Text Available Legionella pneumophila, which is a causative pathogen of Legionnaires' disease, expresses its virulent traits in response to growth conditions. In particular, it is known to become virulent at a post-exponential phase in vitro culture. In this study, we performed a proteomic analysis of differences in expression between the exponential phase and post-exponential phase to identify candidates associated with L. pneumophila virulence using 2-Dimentional Fluorescence Difference Gel Electrophoresis (2D-DIGE combined with Matrix-Assisted Laser Desorption/Ionization-Mass Spectrometry (MALDI-TOF-MS. Of 68 identified proteins that significantly differed in expression between the two growth phases, 64 were up-regulated at a post-exponential phase. The up-regulated proteins included enzymes related to glycolysis, ketone body biogenesis and poly-3-hydroxybutyrate (PHB biogenesis, suggesting that L. pneumophila may utilize sugars and lipids as energy sources, when amino acids become scarce. Proteins related to motility (flagella components and twitching motility-associated proteins were also up-regulated, predicting that they enhance infectivity of the bacteria in host cells under certain conditions. Furthermore, 9 up-regulated proteins of unknown function were found. Two of them were identified as novel bacterial factors associated with hemolysis of sheep red blood cells (SRBCs. Another 2 were found to be translocated into macrophages via the Icm/Dot type IV secretion apparatus as effector candidates in a reporter assay with Bordetella pertussis adenylate cyclase. The study will be helpful for virulent analysis of L. pneumophila from the viewpoint of physiological or metabolic modulation dependent on growth phase.

  8. Trans-Cinnamaldehyde, Carvacrol, and Eugenol Reduce Campylobacter jejuni Colonization Factors and Expression of Virulence Genes in Vitro

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    Dan J. Donoghue

    2017-04-01

    Full Text Available Campylobacter jejuni is a major foodborne pathogen that causes severe gastroenteritis in humans characterized by fever, diarrhea, and abdominal cramps. In the human gut, Campylobacter adheres and invades the intestinal epithelium followed by cytolethal distending toxin mediated cell death, and enteritis. Reducing the attachment and invasion of Campylobacter to intestinal epithelium and expression of its virulence factors such as motility and cytolethal distending toxin (CDT production could potentially reduce infection in humans. This study investigated the efficacy of sub-inhibitory concentrations (SICs, concentration not inhibiting bacterial growth of three GRAS (generally recognized as safe status phytochemicals namely trans-cinnamaldehyde (TC; 0.005, 0.01%, carvacrol (CR; 0.001, 0.002%, and eugenol (EG; 0.005, 0.01% in reducing the attachment, invasion, and translocation of C. jejuni on human intestinal epithelial cells (Caco-2. Additionally, the effect of these phytochemicals on Campylobacter motility and CDT production was studied using standard bioassays and gene expression analysis. All experiments had duplicate samples and were replicated three times on three strains (wild type S-8, NCTC 11168, 81–176 of C. jejuni. Data were analyzed using ANOVA with GraphPad ver. 6. Differences between the means were considered significantly different at P < 0.05. The majority of phytochemical treatments reduced C. jejuni adhesion, invasion, and translocation of Caco-2 cells (P < 0.05. In addition, the phytochemicals reduced pathogen motility and production of CDT in S-8 and NCTC 11168 (P < 0.05. Real-time quantitative PCR revealed that phytochemicals reduced the transcription of select C. jejuni genes critical for infection in humans (P < 0.05. Results suggest that TC, CR, and EG could potentially be used to control C. jejuni infection in humans.

  9. Analysis of virulence factors and in vivo biofilm-forming capacity of Yarrowia lipolytica isolated from patients with fungemia.

    Science.gov (United States)

    Abbes, S; Amouri, I; Trabelsi, H; Neji, S; Sellami, H; Rahmouni, F; Makni, F; Rebai, T; Ayadi, A

    2017-02-01

    Yarrowia lipolytica is ubiquitous in the environment, opportunistic, and might be considered as one of the causative agents of catheter-related candidemia. Our work aimed to study some virulence factors of Y. lipolytica such as hydrolases production and biofilm formation with comparison to the most frequent Candida specie in human disease. In sum, 58 clinical isolates of Y. lipolytica, 16 C. glabrata, and 12 C. albicans were collected from Intensive care unit (ICU). All were tested for enzymatic production and biofilm formation. All tested isolates of C. albicans and C. glabrata were able to degrade casein, and 98.2% of Y. lipolytica showed caseinase activity but no gelatinase activity was detected in all isolates. Y. lipolytica strains showed significantly lower (3.4%) in vitro phospholipase activity than C. albicans and C. glabrata (P .05). Concerning biofilm formation, and unlike the results obtained on polystyrene plate, the number of adhered and biofilm cultivable cells obtained by Y. lipolytica after 168 hours of catheter subcutaneous implantation is significantly greater and tends to be more compact and structured hyphal layer. Although C. albicans remains the most pathogenic yeast, development of selective ability of Y. lipolytica to adhere, to form a biofilm on catheter medical devices, and to produce phospholipase and hemolytic enzyme is of particular interest, and it is strongly recommended to be vigilant in the use of medical implanted medical devices, particularly in ICU. © The Author 2016. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. Interaction of Arabidopsis Trihelix-Domain Transcription Factors VFP3 and VFP5 with Agrobacterium Virulence Protein VirF.

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    Elena García-Cano

    Full Text Available Agrobacterium is a natural genetic engineer of plants that exports several virulence proteins into host cells in order to take advantage of the cell machinery to facilitate transformation and support bacterial growth. One of these effectors is the F-box protein VirF, which presumably uses the host ubiquitin/proteasome system (UPS to uncoat the packaging proteins from the invading bacterial T-DNA. By analogy to several other bacterial effectors, VirF most likely has several functions in the host cell and, therefore, several interacting partners among host proteins. Here we identify one such interactor, an Arabidopsis trihelix-domain transcription factor VFP3, and further show that its very close homolog VFP5 also interacted with VirF. Interestingly, interactions of VirF with either VFP3 or VFP5 did not activate the host UPS, suggesting that VirF might play other UPS-independent roles in bacterial infection. To better understand the potential scope of VFP3 function, we used RNAi to reduce expression of the VFP3 gene. Transcriptome profiling of these VFP3-silenced plants using high-throughput cDNA sequencing (RNA-seq revealed that VFP3 substantially affected plant gene expression; specifically, 1,118 genes representing approximately 5% of all expressed genes were significantly either up- or down-regulated in the VFP3 RNAi line compared to wild-type Col-0 plants. Among the 507 up-regulated genes were genes implicated in the regulation of transcription, protein degradation, calcium signaling, and hormone metabolism, whereas the 611 down-regulated genes included those involved in redox regulation, light reactions of photosynthesis, and metabolism of lipids, amino acids, and cell wall. Overall, this pattern of changes in gene expression is characteristic of plants under stress. Thus, VFP3 likely plays an important role in controlling plant homeostasis.

  11. Interaction of Arabidopsis Trihelix-Domain Transcription Factors VFP3 and VFP5 with Agrobacterium Virulence Protein VirF

    Science.gov (United States)

    García-Cano, Elena; Magori, Shimpei; Sun, Qi; Ding, Zehong; Lazarowitz, Sondra G.; Citovsky, Vitaly

    2015-01-01

    Agrobacterium is a natural genetic engineer of plants that exports several virulence proteins into host cells in order to take advantage of the cell machinery to facilitate transformation and support bacterial growth. One of these effectors is the F-box protein VirF, which presumably uses the host ubiquitin/proteasome system (UPS) to uncoat the packaging proteins from the invading bacterial T-DNA. By analogy to several other bacterial effectors, VirF most likely has several functions in the host cell and, therefore, several interacting partners among host proteins. Here we identify one such interactor, an Arabidopsis trihelix-domain transcription factor VFP3, and further show that its very close homolog VFP5 also interacted with VirF. Interestingly, interactions of VirF with either VFP3 or VFP5 did not activate the host UPS, suggesting that VirF might play other UPS-independent roles in bacterial infection. To better understand the potential scope of VFP3 function, we used RNAi to reduce expression of the VFP3 gene. Transcriptome profiling of these VFP3-silenced plants using high-throughput cDNA sequencing (RNA-seq) revealed that VFP3 substantially affected plant gene expression; specifically, 1,118 genes representing approximately 5% of all expressed genes were significantly either up- or down-regulated in the VFP3 RNAi line compared to wild-type Col-0 plants. Among the 507 up-regulated genes were genes implicated in the regulation of transcription, protein degradation, calcium signaling, and hormone metabolism, whereas the 611 down-regulated genes included those involved in redox regulation, light reactions of photosynthesis, and metabolism of lipids, amino acids, and cell wall. Overall, this pattern of changes in gene expression is characteristic of plants under stress. Thus, VFP3 likely plays an important role in controlling plant homeostasis. PMID:26571494

  12. TeA is a key virulence factor for Alternaria alternata (Fr.) Keissler infection of its host.

    Science.gov (United States)

    Kang, Ye; Feng, Hongwei; Zhang, Jingxu; Chen, Shiguo; Valverde, Bernal E; Qiang, Sheng

    2017-06-01

    A toxin-deficient mutant strain, HP001 mutant of Alternaria alternata, whose mycelium is unable to infect its host, produces little tenuazonic acid (TeA) toxin. How TeA plays a role in initiating host infection by A. alternata remains unclear. In this research we use Imaging-PAM based on chlorophyll fluorescence parameters and transmission electron microscopy to explore the role of TeA toxin during the infection process of A. alternata. Photosystem II damage began even before wild type mycelium infected the leaves of its host, croftonweed (Ageratina adenophora). Compared with the wild type, HP001 mutant produces morphologically different colonies, hyphae with thinner cell walls, has higher reactive oxygen species (ROS) content and lower peroxidase activity, and fails to form appressoria on the host surface. Adding TeA toxin allows the mutant to partially recover these characters and more closely resemble the wild type. Additionally, we found that the mutant is able to elicit disease symptoms when its mycelium is placed on leaves whose epidermis has been manually removed, which indicates that TeA may be determinant in the fungus recognition of its plant host. Lack of TeA toxin appears responsible for the loss of pathogenicity of the HP001 mutant. As a key virulence factor, TeA toxin not only damages the host plant but also is involved in maintaining ROS content, host recognition, inducing appressoria to infect the host and for allowing completion of the infection process. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  13. Complete genome sequence of hypervirulent and outbreak-associated Acinetobacter baumannii strain LAC-4: epidemiology, resistance genetic determinants and potential virulence factors

    Science.gov (United States)

    Ou, Hong-Yu; Kuang, Shan N.; He, Xinyi; Molgora, Brenda M.; Ewing, Peter J.; Deng, Zixin; Osby, Melanie; Chen, Wangxue; Xu, H. Howard

    2015-01-01

    Acinetobacter baumannii is an important human pathogen due to its multi-drug resistance. In this study, the genome of an ST10 outbreak A. baumannii isolate LAC-4 was completely sequenced to better understand its epidemiology, antibiotic resistance genetic determinants and potential virulence factors. Compared with 20 other complete genomes of A. baumannii, LAC-4 genome harbors at least 12 copies of five distinct insertion sequences. It contains 12 and 14 copies of two novel IS elements, ISAba25 and ISAba26, respectively. Additionally, three novel composite transposons were identified: Tn6250, Tn6251 and Tn6252, two of which contain resistance genes. The antibiotic resistance genetic determinants on the LAC-4 genome correlate well with observed antimicrobial susceptibility patterns. Moreover, twelve genomic islands (GI) were identified in LAC-4 genome. Among them, the 33.4-kb GI12 contains a large number of genes which constitute the K (capsule) locus. LAC-4 harbors several unique putative virulence factor loci. Furthermore, LAC-4 and all 19 other outbreak isolates were found to harbor a heme oxygenase gene (hemO)-containing gene cluster. The sequencing of the first complete genome of an ST10 A. baumannii clinical strain should accelerate our understanding of the epidemiology, mechanisms of resistance and virulence of A. baumannii. PMID:25728466

  14. A proteomic analysis of the iron response of Photobacterium damselae subsp. damselae reveals metabolic adaptations to iron levels changes and novel potential virulence factors.

    Science.gov (United States)

    Puentes, Beatriz; Balado, Miguel; Bermúdez-Crespo, José; Osorio, Carlos R; Lemos, Manuel L

    2017-03-01

    Photobacterium damselae subsp. damselae (Pdd) is a marine bacterium that can infect numerous species of marine fish as well as other species including humans. Low iron availability is one of the signs that bacterial pathogens can detect in order to begin colonizing their host, and the reduction of iron levels is a nonspecific host defense strategy that prevents bacterial proliferation. In this work a proteomic approach was used to study the gene expression adaptations of a Pdd strain in response to iron availability. A comparative analysis of induced proteins in both high- and low-iron conditions showed profound cellular metabolic adaptations that result, for instance, in amino acid requirement. It also provided important information about the changes that occur in the energetic metabolism induced by the surrounding iron levels, allowing for the identification of novel potential virulence factors. Among others, genes involved in the synthesis and transport of a vibrioferrin-like siderophore were identified for the first time. In addition to plasmid pPHDD1-encoded Dly and HlyA hemolysins, a pPHDD1-borne operon, which may encode a transferrin receptor, was also found. This operon identification suggests that this virulence plasmid could encode so-far unknown additional virulence factors other than hemolysins. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Inhibition of quorum-sensing-controlled virulence factors of Pseudomonas aeruginosa by Murraya koenigii essential oil: a study in a Caenorhabditis elegans infectious model.

    Science.gov (United States)

    Ganesh, P Sankar; Rai, Ravishankar Vittal

    2016-12-01

    The global emergence of antibiotic-resistant strains of Pseudomonas aeruginosa poses a major threat in both hospital environments and the community. P. aeruginosa is an opportunistic human pathogen, and it also infects a wide range of model organisms including the nematode Caenorhabditis elegans. Quorum sensing (QS) mediates cell-to-cell communication in bacteria and has an important role in regulating virulence genes, antibiotic resistance and biofilm formation, which are crucial for establishment of the infection. Expression of many virulence factors such as pyocyanin and proteases in P. aeruginosa is under the control of the QS system, and are mediated by small molecules such as acyl homoserine lactones. Thus, interfering with the QS system would provide alternative ways of controlling the pathogenicity. Murraya koenigii is a medicinal plant widely used in India. The present study investigated the in vivo inhibitory activity of M. koenigii essential oil (EO) on QS-controlled virulence factors of P. aeruginosa PAO1 using C. elegans. M. koenigii EO significantly inhibited the pyocyanin production and staphylolytic LasA activity of P. aeruginosa PAO1. As compared to the control group with 100 % killing of C. elegans, M. koenigii EO was able to rescue an average of 60 % of C. elegans from death due to the toxic effect of P. aeruginosa. Thus, the present study suggests the anti-QS potential of M. koenigii EO which therefore can be considered as a future therapeutic agent for management of P. aeruginosa-mediated infections.

  16. Regulated expression of cyclic AMP-dependent protein kinase A reveals an influence on cell size and the secretion of virulence factors in Cryptococcus neoformans.

    Science.gov (United States)

    Choi, Jaehyuk; Vogl, A Wayne; Kronstad, James W

    2012-08-01

    Cyclic AMP-dependent protein kinase A (PKA) regulates elaboration of the virulence factors melanin and polysaccharide capsule in Cryptococcus neoformans. A mutation in PKA1 encoding the catalytic subunit is known to reduce virulence in mice while a defect in PKR1 encoding the regulatory subunit enhances disease. Here, we constructed strains with galactose-inducible and glucose-repressible versions of PKA1 and PKR1 by inserting the GAL7 promoter upstream of the genes. As expected, no capsule was found in dextrose-containing media for the P(GAL7):PKA1 strain, whereas a large capsule was formed on cells grown in galactose. Along with capsule thickness, high PKA activity also influenced cell size, ploidy and vacuole enlargement, as observed in previous reports of giant/titan cell formation. We employed the regulated strains to test the hypothesis that PKA influences secretion and found that elevated PKA expression positively regulates extracellular protease activity and negatively regulates urease secretion. Furthermore, proper PKA regulation and activity were required for wild-type levels of melanization and laccase activity, as well as correct localization of the enzyme. The latter phenotype is consistent with the discovery that PKA regulates the organization of intracellular membrane compartments. Overall, these results indicate that PKA influences secretion pathways directly related to virulence factor elaboration. © 2012 Blackwell Publishing Ltd.

  17. Novel host-related virulence factors are encoded by squirrelpox virus, the main causative agent of epidemic disease in red squirrels in the UK.

    Directory of Open Access Journals (Sweden)

    Alistair C Darby

    Full Text Available Squirrelpox virus (SQPV shows little evidence for morbidity or mortality in North American grey squirrels (Sciurus carolinensis, in which the virus is endemic. However, more recently the virus has emerged to cause epidemics with high mortality in Eurasian red squirrels (S. vulgaris in Great Britain, which are now threatened. Here we report the genome sequence of SQPV. Comparison with other Poxviridae revealed a core set of poxvirus genes, the phylogeny of which showed SQPV to be in a new Chordopoxvirus subfamily between the Molluscipoxviruses and Parapoxviruses. A number of SQPV genes were related to virulence, including three major histocomaptibility class I homologs, and one CD47 homolog. In addition, a novel potential virulence factor showing homology to mammalian oligoadenylate synthetase (OAS was identified. This family of proteins normally causes activation of an endoribonuclease (RNaseL within infected cells. The putative function of this novel SQPV protein was predicted in silico.

  18. Factor H specifically capture novel Factor H-binding proteins of Streptococcus suis and contribute to the virulence of the bacteria.

    Science.gov (United States)

    Li, Quan; Ma, Caifeng; Fu, Yang; He, Yanan; Yu, Yanfei; Du, Dechao; Yao, Huochun; Lu, Chengping; Zhang, Wei

    2017-03-01

    Factor H (FH), a regulatory protein of the complement system, can bind specifically to factor H-binding proteins (FHBPs) of Streptococcus suis serotype 2 (SS2), which contribute to evasion of host innate immune defenses. In the present study, we aimed to identify novel FHBPs and characterize the biological functions of FH in SS2 pathogenesis. Here, a method that combined proteomics and Far-western blotting was developed to identify the surface FHBPs of SS2. With this method, fourteen potential novel FHBPs were identified among SS2 surface proteins. We selected eight newly identified proteins and further confirmed their binding activity to FH. The binding of SS2 to immobilized FH decreased dramatically after pre-incubation with anti-FHBPs polyclonal antibodies. We showed for the first time that SS2 also interact specifically with mouse FH. Furthermore, we found that FH play an important role in adherence and invasion of SS2 to HEp-2 cells. Additionally, using a mouse model of intraperitoneal challenge, we confirmed that SS2 pre-incubated with FH enhanced bacteremia and brain invasion, compared with SS2 not pretreated with FH. Taken together, this study provides a useful method to characterize the host-bacteria interactions. These results first indicated that binding of FH to the cell surface improved the adherence and invasion of SS2 to HEp-2 cells, promoting SS2 to resist killing and leading to enhance virulence. Copyright © 2016 Elsevier GmbH. All rights reserved.

  19. Crystal Structure of the Cystic Fibrosis Transmembrane Conductance Regulator Inhibitory Factor Cif Reveals Novel Active-Site Features of an Epoxide Hydrolase Virulence Factor

    Energy Technology Data Exchange (ETDEWEB)

    Bahl, C.; Morisseau, C; Bomberger, J; Stanton, B; Hammock, B; O& apos; Toole, G; Madden, D

    2010-01-01

    Cystic fibrosis transmembrane conductance regulator (CFTR) inhibitory factor (Cif) is a virulence factor secreted by Pseudomonas aeruginosa that reduces the quantity of CFTR in the apical membrane of human airway epithelial cells. Initial sequence analysis suggested that Cif is an epoxide hydrolase (EH), but its sequence violates two strictly conserved EH motifs and also is compatible with other {alpha}/{beta} hydrolase family members with diverse substrate specificities. To investigate the mechanistic basis of Cif activity, we have determined its structure at 1.8-{angstrom} resolution by X-ray crystallography. The catalytic triad consists of residues Asp129, His297, and Glu153, which are conserved across the family of EHs. At other positions, sequence deviations from canonical EH active-site motifs are stereochemically conservative. Furthermore, detailed enzymatic analysis confirms that Cif catalyzes the hydrolysis of epoxide compounds, with specific activity against both epibromohydrin and cis-stilbene oxide, but with a relatively narrow range of substrate selectivity. Although closely related to two other classes of {alpha}/{beta} hydrolase in both sequence and structure, Cif does not exhibit activity as either a haloacetate dehalogenase or a haloalkane dehalogenase. A reassessment of the structural and functional consequences of the H269A mutation suggests that Cif's effect on host-cell CFTR expression requires the hydrolysis of an extended endogenous epoxide substrate.

  20. Crystal structure of the cystic fibrosis transmembrane conductance regulator inhibitory factor Cif reveals novel active-site features of an epoxide hydrolase virulence factor.

    Science.gov (United States)

    Bahl, Christopher D; Morisseau, Christophe; Bomberger, Jennifer M; Stanton, Bruce A; Hammock, Bruce D; O'Toole, George A; Madden, Dean R

    2010-04-01

    Cystic fibrosis transmembrane conductance regulator (CFTR) inhibitory factor (Cif) is a virulence factor secreted by Pseudomonas aeruginosa that reduces the quantity of CFTR in the apical membrane of human airway epithelial cells. Initial sequence analysis suggested that Cif is an epoxide hydrolase (EH), but its sequence violates two strictly conserved EH motifs and also is compatible with other alpha/beta hydrolase family members with diverse substrate specificities. To investigate the mechanistic basis of Cif activity, we have determined its structure at 1.8-A resolution by X-ray crystallography. The catalytic triad consists of residues Asp129, His297, and Glu153, which are conserved across the family of EHs. At other positions, sequence deviations from canonical EH active-site motifs are stereochemically conservative. Furthermore, detailed enzymatic analysis confirms that Cif catalyzes the hydrolysis of epoxide compounds, with specific activity against both epibromohydrin and cis-stilbene oxide, but with a relatively narrow range of substrate selectivity. Although closely related to two other classes of alpha/beta hydrolase in both sequence and structure, Cif does not exhibit activity as either a haloacetate dehalogenase or a haloalkane dehalogenase. A reassessment of the structural and functional consequences of the H269A mutation suggests that Cif's effect on host-cell CFTR expression requires the hydrolysis of an extended endogenous epoxide substrate.

  1. The RNA-Binding Chaperone Hfq Is an Important Global Regulator of Gene Expression in Pasteurella multocida and Plays a Crucial Role in Production of a Number of Virulence Factors, Including Hyaluronic Acid Capsule

    OpenAIRE

    Mégroz, Marianne; Kleifeld, Oded; Wright, Amy; Powell, David; Harrison, Paul; Adler, Ben; Harper, Marina; Boyce, John D.

    2016-01-01

    The Gram-negative bacterium Pasteurella multocida is the causative agent of a number of economically important animal diseases, including avian fowl cholera. Numerous P. multocida virulence factors have been identified, including capsule, lipopolysaccharide (LPS), and filamentous hemagglutinin, but little is known about how the expression of these virulence factors is regulated. Hfq is an RNA-binding protein that facilitates riboregulation via interaction with small noncoding RNA (sRNA) molec...

  2. AsnB, regulated by diffusible signal factor and global regulator Clp, is involved in aspartate metabolism, resistance to oxidative stress and virulence in Xanthomonas oryzae pv. oryzicola.

    Science.gov (United States)

    Qian, Guoliang; Liu, Chunhui; Wu, Guichun; Yin, Fangqun; Zhao, Yancun; Zhou, Yijing; Zhang, Yanbing; Song, Zhiwei; Fan, Jiaqin; Hu, Baishi; Liu, Fengquan

    2013-02-01

    Xanthomonas oryzae pv. oryzicola (Xoc) causes bacterial leaf streak in rice, which is a destructive disease worldwide. Xoc virulence factors are regulated by diffusible signal factor (DSF) and the global regulator Clp. In this study, we have demonstrated that asnB (XOC_3054), encoding an asparagine synthetase, is a novel virulence-related gene regulated by both DSF and Clp in Xoc. A sequence analysis revealed that AsnB is highly conserved in Xanthomonas. An asnB mutation in Xoc dramatically impaired pathogen virulence and growth rate in host rice, but did not affect the ability to trigger the hypersensitive response in nonhost (plant) tobacco. Compared with the wild-type strain, the asnB deletion mutant was unable to grow in basic MMX (-) medium (a minimal medium without ammonium sulphate as the nitrogen source) with or without 10 tested nitrogen sources, except asparagine. The disruption of asnB impaired pathogen resistance to oxidative stress and reduced the transcriptional expression of oxyR, katA and katG, which encode three important proteins responsible for hydrogen peroxide (H(2)O(2)) sensing and detoxification in Xanthomonas in the presence of H(2)O(2), and nine important known Xoc virulence-related genes in plant cell-mimicking medium. Furthermore, the asnB mutation did not affect extracellular protease activity, extracellular polysaccharide production, motility or chemotaxis. Taken together, our results demonstrate the role of asnB in Xanthomonas for the first time. © 2012 THE AUTHORS. MOLECULAR PLANT PATHOLOGY © 2012 BSPP AND BLACKWELL PUBLISHING LTD.

  3. Host cell interactions of outer membrane vesicle-associated virulence factors of enterohemorrhagic Escherichia coli O157: Intracellular delivery, trafficking and mechanisms of cell injury.

    Directory of Open Access Journals (Sweden)

    Martina Bielaszewska

    2017-02-01

    Full Text Available Outer membrane vesicles (OMVs are important tools in bacterial virulence but their role in the pathogenesis of infections caused by enterohemorrhagic Escherichia coli (EHEC O157, the leading cause of life-threatening hemolytic uremic syndrome, is poorly understood. Using proteomics, electron and confocal laser scanning microscopy, immunoblotting, and bioassays, we investigated OMVs secreted by EHEC O157 clinical isolates for virulence factors cargoes, interactions with pathogenetically relevant human cells, and mechanisms of cell injury. We demonstrate that O157 OMVs carry a cocktail of key virulence factors of EHEC O157 including Shiga toxin 2a (Stx2a, cytolethal distending toxin V (CdtV, EHEC hemolysin, and flagellin. The toxins are internalized by cells via dynamin-dependent endocytosis of OMVs and differentially separate from vesicles during intracellular trafficking. Stx2a and CdtV-B, the DNase-like CdtV subunit, separate from OMVs in early endosomes. Stx2a is trafficked, in association with its receptor globotriaosylceramide within detergent-resistant membranes, to the Golgi complex and the endoplasmic reticulum from where the catalytic Stx2a A1 fragment is translocated to the cytosol. CdtV-B is, after its retrograde transport to the endoplasmic reticulum, translocated to the nucleus to reach DNA. CdtV-A and CdtV-C subunits remain OMV-associated and are sorted with OMVs to lysosomes. EHEC hemolysin separates from OMVs in lysosomes and targets mitochondria. The OMV-delivered CdtV-B causes cellular DNA damage, which activates DNA damage responses leading to G2 cell cycle arrest. The arrested cells ultimately die of apoptosis induced by Stx2a and CdtV via caspase-9 activation. By demonstrating that naturally secreted EHEC O157 OMVs carry and deliver into cells a cocktail of biologically active virulence factors, thereby causing cell death, and by performing first comprehensive analysis of intracellular trafficking of OMVs and OMV

  4. Host cell interactions of outer membrane vesicle-associated virulence factors of enterohemorrhagic Escherichia coli O157: Intracellular delivery, trafficking and mechanisms of cell injury

    Science.gov (United States)

    Greune, Lilo; Jarosch, Kevin-André; Steil, Daniel; Zhang, Wenlan; He, Xiaohua; Lloubes, Roland; Fruth, Angelika; Kim, Kwang Sik; Schmidt, M. Alexander; Dobrindt, Ulrich; Mellmann, Alexander; Karch, Helge

    2017-01-01

    Outer membrane vesicles (OMVs) are important tools in bacterial virulence but their role in the pathogenesis of infections caused by enterohemorrhagic Escherichia coli (EHEC) O157, the leading cause of life-threatening hemolytic uremic syndrome, is poorly understood. Using proteomics, electron and confocal laser scanning microscopy, immunoblotting, and bioassays, we investigated OMVs secreted by EHEC O157 clinical isolates for virulence factors cargoes, interactions with pathogenetically relevant human cells, and mechanisms of cell injury. We demonstrate that O157 OMVs carry a cocktail of key virulence factors of EHEC O157 including Shiga toxin 2a (Stx2a), cytolethal distending toxin V (CdtV), EHEC hemolysin, and flagellin. The toxins are internalized by cells via dynamin-dependent endocytosis of OMVs and differentially separate from vesicles during intracellular trafficking. Stx2a and CdtV-B, the DNase-like CdtV subunit, separate from OMVs in early endosomes. Stx2a is trafficked, in association with its receptor globotriaosylceramide within detergent-resistant membranes, to the Golgi complex and the endoplasmic reticulum from where the catalytic Stx2a A1 fragment is translocated to the cytosol. CdtV-B is, after its retrograde transport to the endoplasmic reticulum, translocated to the nucleus to reach DNA. CdtV-A and CdtV-C subunits remain OMV-associated and are sorted with OMVs to lysosomes. EHEC hemolysin separates from OMVs in lysosomes and targets mitochondria. The OMV-delivered CdtV-B causes cellular DNA damage, which activates DNA damage responses leading to G2 cell cycle arrest. The arrested cells ultimately die of apoptosis induced by Stx2a and CdtV via caspase-9 activation. By demonstrating that naturally secreted EHEC O157 OMVs carry and deliver into cells a cocktail of biologically active virulence factors, thereby causing cell death, and by performing first comprehensive analysis of intracellular trafficking of OMVs and OMV-delivered virulence factors

  5. New Insights on Thylakoid Biogenesis in Plant Cells.

    Science.gov (United States)

    Bastien, Olivier; Botella, César; Chevalier, Florian; Block, Maryse A; Jouhet, Juliette; Breton, Christelle; Girard-Egrot, Agnès; Maréchal, Eric

    2016-01-01

    Photosynthetic membranes, or thylakoids, are the most extensive membrane system found in the biosphere. They form flattened membrane cisternae in the cytosol of cyanobacteria and in the stroma of chloroplasts. The efficiency of light energy capture and conversion, critical for primary production in ecosystems, relies on the rapid expansion of thylakoids and their versatile reorganization in response to light changes. Thylakoid biogenesis results from the assembly of a lipid matrix combined with the incorporation of protein components. Four lipid classes are conserved from cyanobacteria to chloroplasts: mono- and digalactosyldiacylglycerol, sulfoquinovosyldiacylglycerol, and phosphatidyldiacylglycerol. This review focuses on the production and biophysical properties of galactolipids, making them determinant factors for the nonvesicular/nonlamellar biogenesis and for the three-dimensional architecture of nascent thylakoids. The regulation of MGD1, the committing enzyme of galactolipid biosynthesis in Arabidopsis, via feedback regulatory loops and control of protein binding to membranes, is also detailed. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Coordination of plant mitochondrial biogenesis: keeping pace with cellular requirements.

    Directory of Open Access Journals (Sweden)

    Elina eWelchen

    2014-01-01

    Full Text Available Plant mitochondria are complex organelles that carry out numerous metabolic processes related with the generation of energy for cellular functions and the synthesis and degradation of several compounds. Mitochondria are semiautonomous and dynamic organelles changing in shape, number and composition depending on tissue or developmental stage. The biogenesis of functional mitochondria requires the coordination of genes present both in the nucleus and the organelle. In addition, due to their central role, all processes held inside mitochondria must be finely coordinated with those in other organelles according to cellular demands. Coordination is achieved by transcriptional control of nuclear genes encoding mitochondrial proteins by specific transcription factors that recognize conserved elements in their promoter regions. In turn, the expression of most of these transcription factors is linked to developmental and environmental cues, according to the availability of nutrients, light-dark cycles and warning signals generated in response to stress conditions. Among the signals impacting in the expression of nuclear genes, retrograde signals that originate inside mitochondria help to adjust mitochondrial biogenesis to organelle demands. Adding more complexity, several nuclear encoded proteins are dual localized to mitochondria and either chloroplasts or the nucleus. Dual targeting might establish a crosstalk between the nucleus and cell organelles to ensure a fine coordination of cellular activities. In this article, we discuss how the different levels of coordination of mitochondrial biogenesis interconnect to optimize the function of the organelle according to both internal and external demands.

  7. Regulation of mitochondrial biogenesis during myogenesis

    OpenAIRE

    Remels, A.H.V.; Langen, R.C.J.; Schrauwen, P.; Schaart, G.; Schols, A.M.W.J.; Gosker, H. R.

    2009-01-01

    Abstract Pathways involved in mitochondrial biogenesis associated with myogenic differentiation are poorly defined. Therefore, C2C12 myoblasts were differentiated into multi-nucleated myotubes and parameters/regulators of mitochondrial biogenesis were investigated. Mitochondrial respiration, citrate synthase- and ?-hydroxyacyl-CoA dehydrogenase activity as well as protein content of complexes I, II, III and V of the mitochondrial respiratory chain increased 4-8 fold during differen...

  8. The key sigma factor of transition phase, SigH, controls sporulation, metabolism, and virulence factor expression in Clostridium difficile.

    Science.gov (United States)

    Saujet, Laure; Monot, Marc; Dupuy, Bruno; Soutourina, Olga; Martin-Verstraete, Isabelle

    2011-07-01

    Toxin synthesis in Clostridium difficile increases as cells enter into stationary phase. We first compared the expression profiles of strain 630E during exponential growth and at the onset of stationary phase and showed that genes involved in sporulation, cellular division, and motility, as well as carbon and amino acid metabolism, were differentially expressed under these conditions. We inactivated the sigH gene, which encodes an alternative sigma factor involved in the transition to post-exponential phase in Bacillus subtilis. Then, we compared the expression profiles of strain 630E and the sigH mutant after 10 h of growth. About 60% of the genes that were differentially expressed between exponential and stationary phases, including genes involved in motility, sporulation, and metabolism, were regulated by SigH, which thus appears to be a key regulator of the transition phase in C. difficile. SigH positively controls several genes required for sporulation. Accordingly, sigH inactivation results in an asporogeneous phenotype. The spo0A and CD2492 genes, encoding the master regulator of sporulation and one of its associated kinases, and the spoIIA operon were transcribed from a SigH-dependent promoter. The expression of tcdA and tcdB, encoding the toxins, and of tcdR, encoding the sigma factor required for toxin production, increased in a sigH mutant. Finally, SigH regulates the expression of genes encoding surface-associated proteins, such as the Cwp66 adhesin, the S-layer precursor, and the flagellum components. Among the 286 genes positively regulated by SigH, about 40 transcriptional units presenting a SigH consensus in their promoter regions are good candidates for direct SigH targets.

  9. Regulation of chloroplast biogenesis: the immutans mutant of Arabidopsis

    Energy Technology Data Exchange (ETDEWEB)

    Rodermel, Steven

    2015-11-16

    The immutans (im) variegation mutant of Arabidopsis is an ideal model to gain insight into factors that control chloroplast biogenesis. im defines the gene for PTOX, a plastoquinol terminal oxidase that participates in control of thylakoid redox. Here, we report that the im defect can be suppressed during the late stages of plant development by gigantea (gi2), which defines the gene for GIGANTEA (GI), a central component of the circadian clock that plays a poorly-understood role in diverse plant developmental processes. imgi2 mutants are late-flowering and display other well-known phenotypes associated with gi2, such as starch accumulation and resistance to oxidative stress. We show that the restoration of chloroplast biogenesis in imgi2 is caused by a developmental-specific de-repression of cytokinin signaling that involves crosstalk with signaling pathways mediated by gibberellin (GA) and SPINDLY (SPY), a GA response inhibitor. Suppression of the plastid defect in imgi2 is likely caused by a relaxation of excitation pressures in developing plastids by factors contributed by gi2, including enhanced rates of photosynthesis and increased resistance to oxidative stress. Interestingly, the suppression phenotype of imgi can be mimicked by crossing im with the starch accumulation mutant, sex1, perhaps because sex1 utilizes pathways similar to gi. We conclude that our studies provide a direct genetic linkage between GIGANTEA and chloroplast biogenesis, and we construct a model of interactions between signaling pathways mediated by gi, GA, SPY, cytokinins, and sex1 that are required for chloroplast biogenesis.

  10. The mucoid switch in Pseudomonas aeruginosa represses quorum sensing systems and leads to complex changes to stationary phase virulence factor regulation.

    Directory of Open Access Journals (Sweden)

    Ben Ryall