WorldWideScience

Sample records for bacterial virulence gene

  1. Computational bacterial genome-wide analysis of phylogenetic profiles reveals potential virulence genes of Streptococcus agalactiae.

    Directory of Open Access Journals (Sweden)

    Frank Po-Yen Lin

    Full Text Available The phylogenetic profile of a gene is a reflection of its evolutionary history and can be defined as the differential presence or absence of a gene in a set of reference genomes. It has been employed to facilitate the prediction of gene functions. However, the hypothesis that the application of this concept can also facilitate the discovery of bacterial virulence factors has not been fully examined. In this paper, we test this hypothesis and report a computational pipeline designed to identify previously unknown bacterial virulence genes using group B streptococcus (GBS as an example. Phylogenetic profiles of all GBS genes across 467 bacterial reference genomes were determined by candidate-against-all BLAST searches,which were then used to identify candidate virulence genes by machine learning models. Evaluation experiments with known GBS virulence genes suggested good functional and model consistency in cross-validation analyses (areas under ROC curve, 0.80 and 0.98 respectively. Inspection of the top-10 genes in each of the 15 virulence functional groups revealed at least 15 (of 119 homologous genes implicated in virulence in other human pathogens but previously unrecognized as potential virulence genes in GBS. Among these highly-ranked genes, many encode hypothetical proteins with possible roles in GBS virulence. Thus, our approach has led to the identification of a set of genes potentially affecting the virulence potential of GBS, which are potential candidates for further in vitro and in vivo investigations. This computational pipeline can also be extended to in silico analysis of virulence determinants of other bacterial pathogens.

  2. A functional gene array for detection of bacterial virulence elements

    Energy Technology Data Exchange (ETDEWEB)

    Jaing, C

    2007-11-01

    We report our development of the first of a series of microarrays designed to detect pathogens with known mechanisms of virulence and antibiotic resistance. By targeting virulence gene families as well as genes unique to specific biothreat agents, these arrays will provide important data about the pathogenic potential and drug resistance profiles of unknown organisms in environmental samples. To validate our approach, we developed a first generation array targeting genes from Escherichia coli strains K12 and CFT073, Enterococcus faecalis and Staphylococcus aureus. We determined optimal probe design parameters for microorganism detection and discrimination, measured the required target concentration, and assessed tolerance for mismatches between probe and target sequences. Mismatch tolerance is a priority for this application, due to DNA sequence variability among members of gene families. Arrays were created using the NimbleGen Maskless Array Synthesizer at Lawrence Livermore National Laboratory. Purified genomic DNA from combinations of one or more of the four target organisms, pure cultures of four related organisms, and environmental aerosol samples with spiked-in genomic DNA were hybridized to the arrays. Based on the success of this prototype, we plan to design further arrays in this series, with the goal of detecting all known virulence and antibiotic resistance gene families in a greatly expanded set of organisms.

  3. Both msa genes in Renibacterium salmoninarum are needed for full virulence in bacterial kidney disease.

    Science.gov (United States)

    Coady, Alison M; Murray, Anthony L; Elliott, Diane G; Rhodes, Linda D

    2006-04-01

    Renibacterium salmoninarum, a gram-positive diplococcobacillus that causes bacterial kidney disease among salmon and trout, has two chromosomal loci encoding the major soluble antigen (msa) gene. Because the MSA protein is widely suspected to be an important virulence factor, we used insertion-duplication mutagenesis to generate disruptions of either the msa1 or msa2 gene. Surprisingly, expression of MSA protein in broth cultures appeared unaffected. However, the virulence of either mutant in juvenile chinook salmon (Oncorhynchus tshawytscha) by intraperitoneal challenge was severely attenuated, suggesting that disruption of the msa1 or msa2 gene affected in vivo expression. PMID:16597972

  4. Bacterial proteases and virulence

    DEFF Research Database (Denmark)

    Frees, Dorte; Brøndsted, Lone; Ingmer, Hanne

    Bacterial pathogens rely on proteolysis for variety of purposes during the infection process. In the cytosol, the main proteolytic players are the conserved Clp and Lon proteases that directly contribute to virulence through the timely degradation of virulence regulators and indirectly by providing...... tolerance to adverse conditions such as those experienced in the host. In the membrane, HtrA performs similar functions whereas the extracellular proteases, in close contact with host components, pave the way for spreading infections by degrading host matrix components or interfering with host cell...... cell. These extracellular proteases are activated in complex cascades involving auto-processing and proteolytic maturation. Thus, proteolysis has been adopted by bacterial pathogens at multiple levels to ensure the success of the pathogen in contact with the human host....

  5. Spaceflight Alters Bacterial Gene Expression and Virulence and Reveals Role for Global Regulator Hfq

    Science.gov (United States)

    Wilson, J. W.; Ott, C. M.; zuBentrup, K. Honer; Ramamurthy R.; Quick, L.; Porwollik, S.; Cheng, P.; McClellan, M.; Tsaprailis, G.; Radabaugh, T.; Hunt, A.; Fernandez, D.; Richter, E.; Shah, M.; Kilcoyne, M.; Joshi, L.; Nelman-Gonzalez, M.; Hing, S.; Parra, M.; Dumaras, P.; Norwood, K.; Nickerson, C. A.; Bober, R.; Devich, J.; Ruggles, A.

    2007-01-01

    A comprehensive analysis of both the molecular genetic and phenotypic responses of any organism to the spaceflight environment has never been accomplished due to significant technological and logistical hurdles. Moreover, the effects of spaceflight on microbial pathogenicity and associated infectious disease risks have not been studied. The bacterial pathogen Salmonella typhimurium was grown aboard Space Shuttle mission STS-115 and compared to identical ground control cultures. Global microarray and proteomic analyses revealed 167 transcripts and 73 proteins changed expression with the conserved RNA-binding protein Hfq identified as a likely global regulator involved in the response to this environment. Hfq involvement was confirmed with a ground based microgravity culture model. Spaceflight samples exhibited enhanced virulence in a murine infection model and extracellular matrix accumulation consistent with a biofilm. Strategies to target Hfq and related regulators could potentially decrease infectious disease risks during spaceflight missions and provide novel therapeutic options on Earth.

  6. Selected lactic acid-producing bacterial isolates with the capacity to reduce Salmonella translocation and virulence gene expression in chickens.

    Directory of Open Access Journals (Sweden)

    Xiaojian Yang

    Full Text Available BACKGROUND: Probiotics have been used to control Salmonella colonization/infection in chickens. Yet the mechanisms of probiotic effects are not fully understood. This study has characterized our previously-selected lactic acid-producing bacterial (LAB isolates for controlling Salmonella infection in chickens, particularly the mechanism underlying the control. METHODOLOGY/PRINCIPAL FINDINGS: In vitro studies were conducted to characterize 14 LAB isolates for their tolerance to low pH (2.0 and high bile salt (0.3-1.5% and susceptibility to antibiotics. Three chicken infection trials were subsequently carried out to evaluate four of the isolates for reducing the burden of Salmonella enterica serovar Typhimurium in the broiler cecum. Chicks were gavaged with LAB cultures (10(6-7 CFU/chick or phosphate-buffered saline (PBS at 1 day of age followed by Salmonella challenge (10(4 CFU/chick next day. Samples of cecal digesta, spleen, and liver were examined for Salmonella counts on days 1, 3, or 4 post-challenge. Salmonella in the cecum from Trial 3 was also assessed for the expression of ten virulence genes located in its pathogenicity island-1 (SPI-1. These genes play a role in Salmonella intestinal invasion. Tested LAB isolates (individuals or mixed cultures were unable to lower Salmonella burden in the chicken cecum, but able to attenuate Salmonella infection in the spleen and liver. The LAB treatments also reduced almost all SPI-1 virulence gene expression (9 out of 10 in the chicken cecum, particularly at the low dose. In vitro treatment with the extracellular culture fluid from a LAB culture also down-regulated most SPI-1 virulence gene expression. CONCLUSIONS/SIGNIFICANCE: The possible correlation between attenuation of Salmonella infection in the chicken spleen and liver and reduction of Salmonella SPI-1 virulence gene expression in the chicken cecum by LAB isolates is a new observation. Suppression of Salmonella virulence gene expression in

  7. Reserch Progress on Filtration Technologies of Bacterial Virulence Gene%细菌毒力基因的筛选技术研究进展

    Institute of Scientific and Technical Information of China (English)

    刘利; 胡勇

    2011-01-01

    细菌感染宿主是一个复杂的过程.目前对于细菌的致病机制的研究主要集中在细菌毒力因子的鉴定上,主要通过筛选细菌感染宿主过程中特异表达的毒力基因,探讨其与细菌毒力之间的关系,来达到识别和确定细菌毒力因子的目的.近年来建立的标记突变技术、体内表达技术、差异荧光诱导技术和体内诱生抗原鉴定技术,可高通量地筛选出宿主体内特异表达的已知或者未知的细菌毒力基因.现对目前运用的细菌毒力基因筛选技术的原理及优缺点进行综述.%The process of bacterial infection are very complex. At present, the study on the pathogenesis of bacterial infection was mainly foucussed on the identification of virulence factors. To identify the virulence factors,it is necessary to screen the virulence genes which are specifically induced in host during bacterial infection and discuss the interaction between the virulence genes and the bacterial virulence. In recent years,different filtration technologies were developed to analyze and identify the knowned and unknowned bacterial virulence gene which could be screened with high throughput in vivo,including signature tagged mutagenesis, In vivo expression technology, differential fluorescence induction, and in vivo-induced antigen technology.The principle, advantages and disadvantages of these technologies were reviewed in this article.

  8. Mammalian cell entry genes in Streptomyces may provide clues to the evolution of bacterial virulence

    OpenAIRE

    Clark, Laura C.; Seipke, Ryan F; Pilar Prieto; Joost Willemse; van Wezel, Gilles P; Hutchings, Matthew I; Hoskisson, Paul A.

    2013-01-01

    Understanding the evolution of virulence is key to appreciating the role specific loci play in pathogenicity. Streptomyces species are generally non-pathogenic soil saprophytes, yet within their genome we can find homologues of virulence loci. One example of this is the mammalian cell entry (mce) locus, which has been characterised in Mycobacterium tuberculosis. To investigate the role in Streptomyces we deleted the mce locus and studied its impact on cell survival, morphology and interaction...

  9. Bacterial Sphingomyelinases and Phospholipases as Virulence Factors.

    Science.gov (United States)

    Flores-Díaz, Marietta; Monturiol-Gross, Laura; Naylor, Claire; Alape-Girón, Alberto; Flieger, Antje

    2016-09-01

    Bacterial sphingomyelinases and phospholipases are a heterogeneous group of esterases which are usually surface associated or secreted by a wide variety of Gram-positive and Gram-negative bacteria. These enzymes hydrolyze sphingomyelin and glycerophospholipids, respectively, generating products identical to the ones produced by eukaryotic enzymes which play crucial roles in distinct physiological processes, including membrane dynamics, cellular signaling, migration, growth, and death. Several bacterial sphingomyelinases and phospholipases are essential for virulence of extracellular, facultative, or obligate intracellular pathogens, as these enzymes contribute to phagosomal escape or phagosomal maturation avoidance, favoring tissue colonization, infection establishment and progression, or immune response evasion. This work presents a classification proposal for bacterial sphingomyelinases and phospholipases that considers not only their enzymatic activities but also their structural aspects. An overview of the main physiopathological activities is provided for each enzyme type, as are examples in which inactivation of a sphingomyelinase- or a phospholipase-encoding gene impairs the virulence of a pathogen. The identification of sphingomyelinases and phospholipases important for bacterial pathogenesis and the development of inhibitors for these enzymes could generate candidate vaccines and therapeutic agents, which will diminish the impacts of the associated human and animal diseases. PMID:27307578

  10. Virulence gene regulation inside and outside.

    OpenAIRE

    DiRita, V J; Engleberg, N C; Heath, A; Miller, A.,; Crawford, J A; Yu, R.

    2000-01-01

    Much knowledge about microbial gene regulation and virulence is derived from genetic and biochemical studies done outside of hosts. The aim of this review is to correlate observations made in vitro and in vivo with two different bacterial pathogens in which the nature of regulated gene expression leading to virulence is quite different. The first is Vibrio cholerae, in which the concerted action of a complicated regulatory cascade involving several transcription activators leads ultimately to...

  11. Tracking bacterial virulence: global modulators as indicators

    Science.gov (United States)

    Prieto, Alejandro; Urcola, Imanol; Blanco, Jorge; Dahbi, Ghizlane; Muniesa, Maite; Quirós, Pablo; Falgenhauer, Linda; Chakraborty, Trinad; Hüttener, Mário; Juárez, Antonio

    2016-01-01

    The genomes of Gram-negative bacteria encode paralogues and/or orthologues of global modulators. The nucleoid-associated H-NS and Hha proteins are an example: several enterobacteria such as Escherichia coli or Salmonella harbor H-NS, Hha and their corresponding paralogues, StpA and YdgT proteins, respectively. Remarkably, the genome of the pathogenic enteroaggregative E. coli strain 042 encodes, in addition to the hha and ydgT genes, two additional hha paralogues, hha2 and hha3. We show in this report that there exists a strong correlation between the presence of these paralogues and the virulence phenotype of several E. coli strains. hha2 and hha3 predominate in some groups of intestinal pathogenic E. coli strains (enteroaggregative and shiga toxin-producing isolates), as well as in the widely distributed extraintestinal ST131 isolates. Because of the relationship between the presence of hha2/hha3 and some virulence factors, we have been able to provide evidence for Hha2/Hha3 modulating the expression of the antigen 43 pathogenic determinants. We show that tracking global modulators or their paralogues/orthologues can be a new strategy to identify bacterial pathogenic clones and propose PCR amplification of hha2 and hha3 as a virulence indicator in environmental and clinical E. coli isolates. PMID:27169404

  12. Plant Natural Products Targeting Bacterial Virulence Factors.

    Science.gov (United States)

    Silva, Laura Nunes; Zimmer, Karine Rigon; Macedo, Alexandre José; Trentin, Danielle Silva

    2016-08-24

    Decreased antimicrobial efficiency has become a global public health issue. The paucity of new antibacterial drugs is evident, and the arsenal against infectious diseases needs to be improved urgently. The selection of plants as a source of prototype compounds is appropriate, since plant species naturally produce a wide range of secondary metabolites that act as a chemical line of defense against microorganisms in the environment. Although traditional approaches to combat microbial infections remain effective, targeting microbial virulence rather than survival seems to be an exciting strategy, since the modulation of virulence factors might lead to a milder evolutionary pressure for the development of resistance. Additionally, anti-infective chemotherapies may be successfully achieved by combining antivirulence and conventional antimicrobials, extending the lifespan of these drugs. This review presents an updated discussion of natural compounds isolated from plants with chemically characterized structures and activity against the major bacterial virulence factors: quorum sensing, bacterial biofilms, bacterial motility, bacterial toxins, bacterial pigments, bacterial enzymes, and bacterial surfactants. Moreover, a critical analysis of the most promising virulence factors is presented, highlighting their potential as targets to attenuate bacterial virulence. The ongoing progress in the field of antivirulence therapy may therefore help to translate this promising concept into real intervention strategies in clinical areas. PMID:27437994

  13. Phage-mediated dispersal of biofilm and distribution of bacterial virulence genes is induced by quorum sensing.

    Directory of Open Access Journals (Sweden)

    Friederike S Rossmann

    2015-02-01

    Full Text Available The microbiome and the phage meta-genome within the human gut are influenced by antibiotic treatments. Identifying a novel mechanism, here we demonstrate that bacteria use the universal communication molecule AI-2 to induce virulence genes and transfer them via phage release. High concentrations (i.e. 100 μM of AI-2 promote dispersal of bacteria from already established biofilms, and is associated with release of phages capable of infecting other bacteria. Enterococcus faecalis V583ΔABC harbours 7 prophages in its genome, and a mutant deficient in one of these prophages (i.e. prophage 5 showed a greatly reduced dispersal of biofilm. Infection of a probiotic E. faecalis strain without lytic prophages with prophage 5 resulted in increased biofilm formation and also in biofilm dispersal upon induction with AI-2. Infection of the probiotic E. faecalis strain with phage-containing supernatants released through AI-2 from E. faecalis V583ΔABC resulted in a strong increase in pathogenicity of this strain. The polylysogenic probiotic strain was also more virulent in a mouse sepsis model and a rat endocarditis model. Both AI-2 and ciprofloxacin lead to phage release, indicating that conditions in the gastrointestinal tract of hospitalized patients treated with antibiotics might lead to distribution of virulence genes to apathogenic enterococci and possibly also to other commensals or even to beneficial probiotic strains.

  14. Virulence gene regulation inside and outside.

    Science.gov (United States)

    DiRita, V J; Engleberg, N C; Heath, A; Miller, A; Crawford, J A; Yu, R

    2000-05-29

    Much knowledge about microbial gene regulation and virulence is derived from genetic and biochemical studies done outside of hosts. The aim of this review is to correlate observations made in vitro and in vivo with two different bacterial pathogens in which the nature of regulated gene expression leading to virulence is quite different. The first is Vibrio cholerae, in which the concerted action of a complicated regulatory cascade involving several transcription activators leads ultimately to expression of cholera toxin and the toxin-coregulated pilus. The regulatory cascade is active in vivo and is also required for maintenance of V. cholerae in the intestinal tract during experimental infection. Nevertheless, specific signals predicted to be generated in vivo, such as bile and a temperature of 37 degrees C, have a severe down-modulating effect on activation of toxin and pilus expression. Another unusual aspect of gene regulation in this system is the role played by inner membrane proteins that activate transcription. Although the topology of these proteins suggests an appealing model for signal transduction leading to virulence gene expression, experimental evidence suggests that such a model may be simplistic. In Streptococcus pyogenes, capsule production is critical for virulence in an animal model of necrotizing skin infection. Yet capsule is apparently produced to high levels only from mutation in a two-component regulatory system, CsrR and CsrS. Thus it seems that in V. cholerae a complex regulatory pathway has evolved to control virulence by induction of gene expression in vivo, whereas in S. pyogenes at least one mode of pathogenicity is potentiated by the absence of regulation. PMID:10874738

  15. Mutations in γ-aminobutyric acid (GABA) transaminase genes in plants or Pseudomonas syringae reduce bacterial virulence

    NARCIS (Netherlands)

    D.H. Park; R. Mirabella; P.A. Bronstein; G.M. Preston; M.A. Haring; C.K. Lim; A. Collmer; R.C. Schuurink

    2010-01-01

    Pseudomonas syringae pv. tomato DC3000 is a bacterial pathogen of Arabidopsis and tomato that grows in the apoplast. The non-protein amino acid γ-amino butyric acid (GABA) is produced by Arabidopsis and tomato and is the most abundant amino acid in the apoplastic fluid of tomato. The DC3000 genome h

  16. Regulation of bacterial virulence by Csr (Rsm) systems.

    Science.gov (United States)

    Vakulskas, Christopher A; Potts, Anastasia H; Babitzke, Paul; Ahmer, Brian M M; Romeo, Tony

    2015-06-01

    Most bacterial pathogens have the remarkable ability to flourish in the external environment and in specialized host niches. This ability requires their metabolism, physiology, and virulence factors to be responsive to changes in their surroundings. It is no surprise that the underlying genetic circuitry that supports this adaptability is multilayered and exceedingly complex. Studies over the past 2 decades have established that the CsrA/RsmA proteins, global regulators of posttranscriptional gene expression, play important roles in the expression of virulence factors of numerous proteobacterial pathogens. To accomplish these tasks, CsrA binds to the 5' untranslated and/or early coding regions of mRNAs and alters translation, mRNA turnover, and/or transcript elongation. CsrA activity is regulated by noncoding small RNAs (sRNAs) that contain multiple CsrA binding sites, which permit them to sequester multiple CsrA homodimers away from mRNA targets. Environmental cues sensed by two-component signal transduction systems and other regulatory factors govern the expression of the CsrA-binding sRNAs and, ultimately, the effects of CsrA on secretion systems, surface molecules and biofilm formation, quorum sensing, motility, pigmentation, siderophore production, and phagocytic avoidance. This review presents the workings of the Csr system, the paradigm shift that it generated for understanding posttranscriptional regulation, and its roles in virulence networks of animal and plant pathogens. PMID:25833324

  17. Impact of CRISPR immunity on the emergence and virulence of bacterial pathogens

    OpenAIRE

    Hatoum-Aslan, Asma; Marraffini, Luciano A.

    2013-01-01

    CRISPR-Cas systems protect prokaryotes from viruses and plasmids and function primarily as an adaptive immune system in these organisms. Recent discoveries, however, revealed unexpected roles for CRISPR loci as barriers to horizontal gene transfer and as modulators of gene expression. We review how both of these functions of CRISPR-Cas systems can affect the emergence and virulence of human bacterial pathogens.

  18. The Chaotic Structure of Bacterial Virulence Protein Sequences

    Directory of Open Access Journals (Sweden)

    Sevdanur Genc

    2015-01-01

    Full Text Available Bacterial virulence proteins, which have been class ified on structure of virulence, causes several diseases. For instance, Adhesins play an important role in th e host cells. They are inserted DNA sequences for a variety of virulence properties. Several important methods conducted for the prediction of bacterial virulence proteins for finding new drugs or vaccines. In this study, we propose a method for feature sele ction about classification of bacterial virulence protein. The features are constituted dir ectly from the amino acid sequence of a given protein. Amino acids form proteins, which are criti cal to life, and have many important functions in living cells. They occurring with diff erent physicochemical properties by a vector of 20 numerical values, and collected in AAIndex datab ases of known 544 indices. For all that, this approach have two steps. Firstly , the amino acid sequence of a given protein analysed with Lyapunov Exponents that they have a chaotic structure in accordance wi th the chaos theory. After that, if the results show chara cterization over the complete distribution in the phase space from the point of deterministic sys tem, it means related protein will show a chaotic structure. Empirical results revealed that generated feature v ectors give the best performance with chaotic structure of physicochemical features of amino acid s with Adhesins and non-Adhesins data sets.

  19. Different food sources elicit fast changes to bacterial virulence.

    Science.gov (United States)

    Ketola, T; Mikonranta, L; Laakso, J; Mappes, J

    2016-01-01

    Environmentally transmitted, opportunistic bacterial pathogens have a life cycle that alternates between hosts and environmental reservoirs. Resources are often scarce and fluctuating in the outside-host environment, whereas overcoming the host immune system could allow pathogens to establish a new, resource abundant and stable niche within the host. We tested if short-term exposure to different outside-host resource types and concentrations affect Serratia marcescens-(bacterium)'s virulence in Galleria mellonella (moth). As expected, virulence was mostly dictated by the bacterial dose, but we also found a clear increase in virulence when the bacterium had inhabited a low (versus high) resource concentration, or animal-based (versus plant-based) resources for 48 h prior to injection. The results suggest that temporal changes in pathogen's resource environment can induce very rapid changes in virulence and affect infection severity. Such changes could also play an important role in shifts from environmental lifestyle to pathogenicity or switches in host range and have implications for the management of opportunistic pathogens and disease outbreaks. PMID:26763215

  20. Regulation of Bacterial Virulence by Csr (Rsm) Systems

    OpenAIRE

    Vakulskas, Christopher A.; Potts, Anastasia H.; Babitzke, Paul; Ahmer, Brian M. M.; Romeo, Tony

    2015-01-01

    Most bacterial pathogens have the remarkable ability to flourish in the external environment and in specialized host niches. This ability requires their metabolism, physiology, and virulence factors to be responsive to changes in their surroundings. It is no surprise that the underlying genetic circuitry that supports this adaptability is multilayered and exceedingly complex. Studies over the past 2 decades have established that the CsrA/RsmA proteins, global regulators of posttranscriptional...

  1. Interplay between genetic regulation of phosphate homeostasis and bacterial virulence

    OpenAIRE

    Chekabab, Samuel Mohammed; Harel, Josée; Dozois, Charles M.

    2014-01-01

    Bacterial pathogens, including those of humans, animals, and plants, encounter phosphate (Pi)-limiting or Pi-rich environments in the host, depending on the site of infection. The environmental Pi-concentration results in modulation of expression of the Pho regulon that allows bacteria to regulate phosphate assimilation pathways accordingly. In many cases, modulation of Pho regulon expression also results in concomitant changes in virulence phenotypes. Under Pi-limiting conditions, bacteria u...

  2. From cholera to corals: Viruses as drivers of virulence in a major coral bacterial pathogen

    KAUST Repository

    Weynberg, Karen D.

    2015-12-08

    Disease is an increasing threat to reef-building corals. One of the few identified pathogens of coral disease is the bacterium Vibrio coralliilyticus. In Vibrio cholerae, infection by a bacterial virus (bacteriophage) results in the conversion of non-pathogenic strains to pathogenic strains and this can lead to cholera pandemics. Pathogenicity islands encoded in the V. cholerae genome play an important role in pathogenesis. Here we analyse five whole genome sequences of V. coralliilyticus to examine whether virulence is similarly driven by horizontally acquired elements. We demonstrate that bacteriophage genomes encoding toxin genes with homology to those found in pathogenic V. cholerae are integrated in V. coralliilyticus genomes. Virulence factors located on chromosomal pathogenicity islands also exist in some strains of V. coralliilyticus. The presence of these genetic signatures indicates virulence in V. coralliilyticus is driven by prophages and other horizontally acquired elements. Screening for pathogens of coral disease should target conserved regions in these elements.

  3. 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

    Bacterial pathogens detect and integrate multiple environmental signals to coordinate appropriate changes in gene expression including the selective expression of virulence factors, changes to metabolism and the activation of stress response systems. Mutations that abolish the ability of the...... lysine residue in the translation factor elongation factor P (EF-P). Strains in which EF-P is unmodified due to the absence of PoxA or YjeK are attenuated for virulence and display highly pleiotropic phenotypes, including hypersusceptibility to a wide range of unrelated antimicrobial compounds. Work from...... 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...

  4. Sustainability of virulence in a phage-bacterial ecosystem.

    Science.gov (United States)

    Heilmann, Silja; Sneppen, Kim; Krishna, Sandeep

    2010-03-01

    Virulent phages and their bacterial hosts represent an unusual sort of predator-prey system where each time a prey is eaten, hundreds of new predators are born. It is puzzling how, despite the apparent effectiveness of the phage predators, they manage to avoid driving their bacterial prey to extinction. Here we consider a phage-bacterial ecosystem on a two-dimensional (2-d) surface and show that homogeneous space in itself enhances coexistence. We analyze different behavioral mechanisms that can facilitate coexistence in a spatial environment. For example, we find that when the latent times of the phage are allowed to evolve, selection favors "mediocre killers," since voracious phage rapidly deplete local resources and go extinct. Our model system thus emphasizes the differences between short-term proliferation and long-term ecosystem sustainability. PMID:20071588

  5. Virulence Program of a Bacterial Plant Pathogen: The Dickeya Model.

    Science.gov (United States)

    Reverchon, S; Muskhelisvili, G; Nasser, W

    2016-01-01

    The pectinolytic Dickeya spp. are Gram-negative bacteria causing severe disease in a wide range of plant species. Although the Dickeya genus was initially restricted to tropical and subtropical areas, two Dickeya species (D. dianthicola and D. solani) emerged recently in potato cultures in Europe. Soft-rot, the visible symptoms, is caused by plant cell wall degrading enzymes, mainly pectate lyases (Pels) that cleave the pectin polymer. However, an efficient colonization of the host requires many additional elements including early factors (eg, flagella, lipopolysaccharide, and exopolysaccharide) that allow adhesion of the bacteria and intermediate factors involved in adaptation to new growth conditions encountered in the host (eg, oxidative stress, iron starvation, and toxic compounds). To facilitate this adaptation, Dickeya have developed complex regulatory networks ensuring appropriate expression of virulence genes. This review presents recent advances in our understanding of the signals and genetic circuits impacting the expression of virulence determinants. Special attention is paid to integrated control of virulence functions by variations in the superhelical density of chromosomal DNA, and the global and specific regulators, making the regulation of Dickeya virulence an especially attractive model for those interested in relationships between the chromosomal dynamics and gene regulatory networks. PMID:27571692

  6. Importance of prophages to evolution and virulence of bacterial pathogens.

    Science.gov (United States)

    Fortier, Louis-Charles; Sekulovic, Ognjen

    2013-07-01

    Bacteriophages, or simply phages, are viruses infecting bacteria. With an estimated 10 ( 31) particles in the biosphere, phages outnumber bacteria by a factor of at least 10 and not surprisingly, they influence the evolution of most bacterial species, sometimes in unexpected ways. "Temperate" phages have the ability to integrate into the chromosome of their host upon infection, where they can reside as "quiescent" prophages until conditions favor their reactivation. Lysogenic conversion resulting from the integration of prophages encoding powerful toxins is probably the most determinant contribution of prophages to the evolution of pathogenic bacteria. We currently grasp only a small fraction of the total phage diversity. Phage biologists keep unraveling novel mechanisms developed by phages to parasitize their host. The purpose of this review is to give an overview of some of the various ways by which prophages change the lifestyle and boost virulence of some of the most dangerous bacterial pathogens. PMID:23611873

  7. Development of Quorum-Based Anti-Virulence Therapeutics Targeting Gram-Negative Bacterial Pathogens

    Directory of Open Access Journals (Sweden)

    Wen Shan Yew

    2013-08-01

    Full Text Available Quorum sensing is a cell density-dependent signaling phenomenon used by bacteria for coordination of population-wide phenotypes, such as expression of virulence genes, antibiotic resistance and biofilm formation. Lately, disruption of bacterial communication has emerged as an anti-virulence strategy with enormous therapeutic potential given the increasing incidences of drug resistance in pathogenic bacteria. The quorum quenching therapeutic approach promises a lower risk of resistance development, since interference with virulence generally does not affect the growth and fitness of the bacteria and, hence, does not exert an associated selection pressure for drug-resistant strains. With better understanding of bacterial communication networks and mechanisms, many quorum quenching methods have been developed against various clinically significant bacterial pathogens. In particular, Gram-negative bacteria are an important group of pathogens, because, collectively, they are responsible for the majority of hospital-acquired infections. Here, we discuss the current understanding of existing quorum sensing mechanisms and present important inhibitory strategies that have been developed against this group of pathogenic bacteria.

  8. Identification of novel virulence-associated genes via genome analysis of hypothetical genes.

    Science.gov (United States)

    Garbom, Sara; Forsberg, Ake; Wolf-Watz, Hans; Kihlberg, Britt-Marie

    2004-03-01

    The sequencing of bacterial genomes has opened new perspectives for identification of targets for treatment of infectious diseases. We have identified a set of novel virulence-associated genes (vag genes) by comparing the genome sequences of six human pathogens that are known to cause persistent or chronic infections in humans: Yersinia pestis, Neisseria gonorrhoeae, Helicobacter pylori, Borrelia burgdorferi, Streptococcus pneumoniae, and Treponema pallidum. This comparison was limited to genes annotated as hypothetical in the T. pallidum genome project. Seventeen genes with unknown functions were found to be conserved among these pathogens. Insertional inactivation of 14 of these genes generated nine mutants that were attenuated for virulence in a mouse infection model. Out of these nine genes, five were found to be specifically associated with virulence in mice as demonstrated by infection with Yersinia pseudotuberculosis in-frame deletion mutants. In addition, these five vag genes were essential only in vivo, since all the mutants were able to grow in vitro. These genes are broadly conserved among bacteria. Therefore, we propose that the corresponding vag gene products may constitute novel targets for antimicrobial therapy and that some vag mutants could serve as carrier strains for live vaccines. PMID:14977936

  9. Chamaecyparis obtusa Suppresses Virulence Genes in Streptococcus mutans

    Science.gov (United States)

    Kim, Eun-Hee; Kang, Sun-Young; Park, Bog-Im; Kim, Young-Hoi; Lee, Young-Rae; Hoe, Jin-Hee; Choi, Na-Young; Ra, Ji-Young; An, So-Youn; You, Yong-Ouk

    2016-01-01

    Chamaecyparis obtusa (C. obtusa) is known to have antimicrobial effects and has been used as a medicinal plant and in forest bathing. This study aimed to evaluate the anticariogenic activity of essential oil of C. obtusa on Streptococcus mutans, which is one of the most important bacterial causes of dental caries and dental biofilm formation. Essential oil from C. obtusa was extracted, and its effect on bacterial growth, acid production, and biofilm formation was evaluated. C. obtusa essential oil exhibited concentration-dependent inhibition of bacterial growth over 0.025 mg/mL, with 99% inhibition at a concentration of 0.2 mg/mL. The bacterial biofilm formation and acid production were also significantly inhibited at the concentration greater than 0.025 mg/mL. The result of LIVE/DEAD® BacLight™ Bacterial Viability Kit showed a concentration-dependent bactericidal effect on S. mutans and almost all bacteria were dead over 0.8 mg/mL. Real-time PCR analysis showed that gene expression of some virulence factors such as brpA, gbpB, gtfC, and gtfD was also inhibited. In GC and GC-MS analysis, the major components were found to be α-terpinene (40.60%), bornyl acetate (12.45%), α-pinene (11.38%), β-pinene (7.22%), β-phellandrene (3.45%), and α-terpinolene (3.40%). These results show that C. obtusa essential oil has anticariogenic effect on S. mutans. PMID:27293453

  10. The Salmonella enterica virulence : Its role in bacterial adaption to mammalian and protozoan cells

    OpenAIRE

    Tezcan-Merdol, Dilek

    2004-01-01

    Salmonellae are Gram-negative enteric bacteria and facultative intracellular pathogens responsible for a diversity of illnesses in a wide range of hosts, including man. Many serovars of Salmonella enterica harbor a plasmid that enhances bacterial virulence in infection models, and that seems to promote extraintestinal infection in man. Consequently, the plasmid has been referred to as the"virulence plasmid". The virulence plasmid varies in its constitution among different se...

  11. Polynucleotide Phosphorylase Negatively Controls spv Virulence Gene Expression in Salmonella enterica †

    OpenAIRE

    Ygberg, Sofia Eriksson; Clements, Mark O.; Rytkönen, Anne; Thompson, Arthur; Holden, David W.; Hinton, Jay C. D.; Rhen, Mikael

    2006-01-01

    Mutational inactivation of the cold-shock-associated exoribonuclease polynucleotide phosphorylase (PNPase; encoded by the pnp gene) in Salmonella enterica serovar Typhimurium was previously shown to enable the bacteria to cause chronic infection and to affect the bacterial replication in BALB/c mice (M. O. Clements et al., Proc. Natl. Acad. Sci. USA 99:8784-8789, 2002). Here, we report that PNPase deficiency results in increased expression of Salmonella plasmid virulence (spv) genes under in ...

  12. Candidate Targets for New Anti-Virulence Drugs: Selected Cases of Bacterial Adhesion and Biofilm Formation

    DEFF Research Database (Denmark)

    Klemm, Per; Hancock, Viktoria; Kvist, Malin;

    2007-01-01

    Management of bacterial infections is becoming increasingly difficult due to the rising frequency of strains that are resistant to many current antibiotics. New types of antibiotics are, therefore, urgently needed. Virulence factors or virulence-associated phenotypes such as adhesins and biofilm...

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

    Directory of Open Access Journals (Sweden)

    J Udayalaxmi

    2011-01-01

    Full Text Available 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.

  14. 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. PMID:21654113

  15. Using an in-vitro biofilm model to assess the virulence potential of bacterial vaginosis or non-bacterial vaginosis Gardnerella vaginalis isolates.

    Science.gov (United States)

    Castro, Joana; Alves, Patrícia; Sousa, Cármen; Cereija, Tatiana; França, Ângela; Jefferson, Kimberly K; Cerca, Nuno

    2015-01-01

    Gardnerella vaginalis is the most common species found in bacterial vaginosis (BV). However, it is also present in a significant proportion of healthy women and G. vaginalis vaginal colonization does not always lead to BV. In an effort to better understand the differences between G. vaginalis isolated from women with a positive (BV) versus a negative (non-BV) diagnosis of BV, we compared the virulence potential of 7 BV and 7 non-BV G. vaginalis isolates and assessed the virulence factors related to biofilm formation, namely: initial adhesion and cytotoxic effect, biofilm accumulation, susceptibility to antibiotics, and transcript levels of the known vaginolysin, and sialidase genes. Furthermore, we also determined the ability of G. vaginalis to displace lactobacilli previously adhered to HeLa cells. Our results showed that non-BV strains were less virulent than BV strains, as suggested by the lower cytotoxicity and initial adhesion to Hela cells. Significant differences in expression of known virulence genes were also detected, further suggesting a higher virulence potential of the BV associated G. vaginalis. Importantly, we demonstrated that BV associated G. vaginalis were able to displace pre-coated vaginal protective lactobacilli and we hypothesize this to be a trigger for BV development. PMID:26113465

  16. Ndk, a novel host-responsive regulator, negatively regulates bacterial virulence through quorum sensing in Pseudomonas aeruginosa

    Science.gov (United States)

    Yu, Hua; Xiong, Junzhi; Zhang, Rong; Hu, Xiaomei; Qiu, Jing; Zhang, Di; Xu, Xiaohui; Xin, Rong; He, Xiaomei; Xie, Wei; Sheng, Halei; Chen, Qian; Zhang, Le; Rao, Xiancai; Zhang, Kebin

    2016-01-01

    Pathogenic bacteria could adjust gene expression to enable their survival in the distinct host environment. However, the mechanism by which bacteria adapt to the host environment is not well described. In this study, we demonstrated that nucleoside diphosphate kinase (Ndk) of Pseudomonas aeruginosa is critical for adjusting the bacterial virulence determinants during infection. Ndk expression was down-regulated in the pulmonary alveoli of a mouse model of acute pneumonia. Knockout of ndk up-regulated transcription factor ExsA-mediated T3S regulon expression and decreased exoproduct-related gene expression through the inhibition of the quorum sensing hierarchy. Moreover, in vitro and in vivo studies demonstrated that the ndk mutant exhibits enhanced cytotoxicity and host pathogenicity by increasing T3SS proteins. Taken together, our data reveal that ndk is a critical novel host-responsive gene required for coordinating P. aeruginosa virulence upon acute infection. PMID:27345215

  17. Ndk, a novel host-responsive regulator, negatively regulates bacterial virulence through quorum sensing in Pseudomonas aeruginosa.

    Science.gov (United States)

    Yu, Hua; Xiong, Junzhi; Zhang, Rong; Hu, Xiaomei; Qiu, Jing; Zhang, Di; Xu, Xiaohui; Xin, Rong; He, Xiaomei; Xie, Wei; Sheng, Halei; Chen, Qian; Zhang, Le; Rao, Xiancai; Zhang, Kebin

    2016-01-01

    Pathogenic bacteria could adjust gene expression to enable their survival in the distinct host environment. However, the mechanism by which bacteria adapt to the host environment is not well described. In this study, we demonstrated that nucleoside diphosphate kinase (Ndk) of Pseudomonas aeruginosa is critical for adjusting the bacterial virulence determinants during infection. Ndk expression was down-regulated in the pulmonary alveoli of a mouse model of acute pneumonia. Knockout of ndk up-regulated transcription factor ExsA-mediated T3S regulon expression and decreased exoproduct-related gene expression through the inhibition of the quorum sensing hierarchy. Moreover, in vitro and in vivo studies demonstrated that the ndk mutant exhibits enhanced cytotoxicity and host pathogenicity by increasing T3SS proteins. Taken together, our data reveal that ndk is a critical novel host-responsive gene required for coordinating P. aeruginosa virulence upon acute infection. PMID:27345215

  18. Construction of a Multiplex Promoter Reporter Platform to Monitor Staphylococcus aureus Virulence Gene Expression and the Identification of Usnic Acid as a Potent Suppressor of psm Gene Expression.

    Science.gov (United States)

    Gao, Peng; Wang, Yanli; Villanueva, Iván; Ho, Pak Leung; Davies, Julian; Kao, Richard Yi Tsun

    2016-01-01

    As antibiotic resistance becomes phenomenal, alternative therapeutic strategies for bacterial infections such as anti-virulence treatments have been advocated. We have constructed a total of 20 gfp-luxABCDE dual-reporter plasmids with selected promoters from S. aureus virulence-associated genes. The plasmids were introduced into various S. aureus strains to establish a gfp-lux based multiplex promoter reporter platform for monitoring S. aureus virulence gene expressions in real time to identify factors or compounds that may perturb virulence of S. aureus. The gene expression profiles monitored by luminescence correlated well with qRT-PCR results and extrinsic factors including carbon dioxide and some antibiotics were shown to suppress or induce the expression of virulence factors in this platform. Using this platform, sub-inhibitory ampicillin was shown to be a potent inducer for the expression of many virulence factors in S. aureus. Bacterial adherence and invasion assays using mammalian cells were employed to measure S. aureus virulence induced by ampicillin. The platform was used for screening of natural extracts that perturb the virulence of S. aureus and usnic acid was identified to be a potent repressor for the expression of psm. PMID:27625639

  19. Analysis of RogB-Controlled Virulence Mechanisms and Gene Expression in Streptococcus agalactiae

    OpenAIRE

    Gutekunst, Heike; Eikmanns, Bernhard J.; Reinscheid, Dieter J.

    2003-01-01

    Streptococcus agalactiae is the leading cause of bacterial sepsis and meningitis in neonates and also the causative agent of different serious infections in immunocompromised adults. The wide range of diseases that are caused by S. agalactiae suggests regulatory mechanisms that control the formation of specific virulence factors in these bacteria. The present study describes a gene from S. agalactiae, designated rogB, encoding a protein with significant similarity to members of the RofA-like ...

  20. Comparative genomics of the bacterial genus Listeria: Genome evolution is characterized by limited gene acquisition and limited gene loss

    OpenAIRE

    den Bakker, Henk C.; Cummings, Craig A.; Ferreira, Vania; Vatta, Paolo; Orsi, Renato H.; Degoricija, Lovorka; Barker, Melissa; Petrauskene, Olga; Furtado, Manohar R; Wiedmann, Martin

    2010-01-01

    Background The bacterial genus Listeria contains pathogenic and non-pathogenic species, including the pathogens L. monocytogenes and L. ivanovii, both of which carry homologous virulence gene clusters such as the prfA cluster and clusters of internalin genes. Initial evidence for multiple deletions of the prfA cluster during the evolution of Listeria indicates that this genus provides an interesting model for studying the evolution of virulence and also presents practical challenges with rega...

  1. Steps toward broad-spectrum therapeutics: discovering virulence-associated genes present in diverse human pathogens

    Directory of Open Access Journals (Sweden)

    de Rochefort Anna

    2009-10-01

    Full Text Available Abstract Background New and improved antimicrobial countermeasures are urgently needed to counteract increased resistance to existing antimicrobial treatments and to combat currently untreatable or new emerging infectious diseases. We demonstrate that computational comparative genomics, together with experimental screening, can identify potential generic (i.e., conserved across multiple pathogen species and novel virulence-associated genes that may serve as targets for broad-spectrum countermeasures. Results Using phylogenetic profiles of protein clusters from completed microbial genome sequences, we identified seventeen protein candidates that are common to diverse human pathogens and absent or uncommon in non-pathogens. Mutants of 13 of these candidates were successfully generated in Yersinia pseudotuberculosis and the potential role of the proteins in virulence was assayed in an animal model. Six candidate proteins are suggested to be involved in the virulence of Y. pseudotuberculosis, none of which have previously been implicated in the virulence of Y. pseudotuberculosis and three have no record of involvement in the virulence of any bacteria. Conclusion This work demonstrates a strategy for the identification of potential virulence factors that are conserved across a number of human pathogenic bacterial species, confirming the usefulness of this tool.

  2. Bistable expression of virulence genes in salmonella leads to the formation of an antibiotic-tolerant subpopulation.

    Directory of Open Access Journals (Sweden)

    Markus Arnoldini

    2014-08-01

    Full Text Available Phenotypic heterogeneity can confer clonal groups of organisms with new functionality. A paradigmatic example is the bistable expression of virulence genes in Salmonella typhimurium, which leads to phenotypically virulent and phenotypically avirulent subpopulations. The two subpopulations have been shown to divide labor during S. typhimurium infections. Here, we show that heterogeneous virulence gene expression in this organism also promotes survival against exposure to antibiotics through a bet-hedging mechanism. Using microfluidic devices in combination with fluorescence time-lapse microscopy and quantitative image analysis, we analyzed the expression of virulence genes at the single cell level and related it to survival when exposed to antibiotics. We found that, across different types of antibiotics and under concentrations that are clinically relevant, the subpopulation of bacterial cells that express virulence genes shows increased survival after exposure to antibiotics. Intriguingly, there is an interplay between the two consequences of phenotypic heterogeneity. The bet-hedging effect that arises through heterogeneity in virulence gene expression can protect clonal populations against avirulent mutants that exploit and subvert the division of labor within these populations. We conclude that bet-hedging and the division of labor can arise through variation in a single trait and interact with each other. This reveals a new degree of functional complexity of phenotypic heterogeneity. In addition, our results suggest a general principle of how pathogens can evade antibiotics: Expression of virulence factors often entails metabolic costs and the resulting growth retardation could generally increase tolerance against antibiotics and thus compromise treatment.

  3. Central regulatory role for the RpoS sigma factor in expression of Salmonella dublin plasmid virulence genes.

    OpenAIRE

    Chen, C Y; Buchmeier, N A; Libby, S.; Fang, F C; Krause, M.; Guiney, D G

    1995-01-01

    The plasmid virulence genes spvABCD of Salmonella spp. are regulated by SpvR and the stationary-phase sigma factor RpoS. The transcription of spv genes is induced during the post-exponential phase of bacterial growth in vitro. We sought to investigate the relationship between growth phase and RpoS in spv regulation. rpoS insertion mutations were constructed in S. dublin Lane and plasmid-cured LD842 strains, and the mutants were found to be attenuated for virulence and deficient in spv gene ex...

  4. Effects of a Mutation in the gyrA Gene on the Virulence of Uropathogenic Escherichia coli

    OpenAIRE

    Sánchez-Céspedes, Javier; Sáez-López, Emma; Frimodt-Møller, N.; Vila, Jordi; Soto, Sara M.

    2015-01-01

    Fluoroquinolones are among the drugs most extensively used for the treatment of bacterial infections in human and veterinary medicine. Resistance to quinolones can be chromosome or plasmid mediated. The chromosomal mechanism of resistance is associated with mutations in the DNA gyrase- and topoisomerase IV-encoding genes and mutations in regulatory genes affecting different efflux systems, among others. We studied the role of the acquisition of a mutation in the gyrA gene in the virulence and...

  5. Dynamics of bacterial gene regulation

    Science.gov (United States)

    Narang, Atul

    2009-03-01

    The phenomenon of diauxic growth is a classical problem of bacterial gene regulation. The most well studied example of this phenomenon is the glucose-lactose diauxie, which occurs because the expression of the lac operon is strongly repressed in the presence of glucose. This repression is often explained by appealing to molecular mechanisms such as cAMP activation and inducer exclusion. I will begin by analyzing data showing that these molecular mechanisms cannot explain the strong lac repression because they exert a relatively weak effect. I will then present a minimal model accounting only for enzyme induction and dilution, which yields strong repression despite the absence of catabolite repression and inducer exclusion. The model also explains the growth patterns observed in batch and continuous cultures of various bacterial strains and substrate mixtures. The talk will conclude with a discussion of the experimental evidence regarding positive feedback, the key component of the minimal model.

  6. Novel inhibitors of Staphylococcus aureus virulence gene expression and biofilm formation.

    Directory of Open Access Journals (Sweden)

    Yibao Ma

    Full Text Available Staphylococcus aureus is a major human pathogen and one of the more prominent pathogens causing biofilm related infections in clinic. Antibiotic resistance in S. aureus such as methicillin resistance is approaching an epidemic level. Antibiotic resistance is widespread among major human pathogens and poses a serious problem for public health. Conventional antibiotics are either bacteriostatic or bacteriocidal, leading to strong selection for antibiotic resistant pathogens. An alternative approach of inhibiting pathogen virulence without inhibiting bacterial growth may minimize the selection pressure for resistance. In previous studies, we identified a chemical series of low molecular weight compounds capable of inhibiting group A streptococcus virulence following this alternative anti-microbial approach. In the current study, we demonstrated that two analogs of this class of novel anti-virulence compounds also inhibited virulence gene expression of S. aureus and exhibited an inhibitory effect on S. aureus biofilm formation. This class of anti-virulence compounds could be a starting point for development of novel anti-microbial agents against S. aureus.

  7. Structure of the autoinducer required for expression of Pseudomonas aeruginosa virulence genes.

    OpenAIRE

    Pearson, J P; Gray, K. M.; Passador, L.; Tucker, K D; Eberhard, A.; Iglewski, B H; Greenberg, E P

    1994-01-01

    In Pseudomonas aeruginosa the LasR protein is required for activation of lasB and several other virulence genes. A diffusible signal molecule, the P. aeruginosa autoinducer (PAI), produced by the bacterial cell and released into the growth medium, is required for activity of LasR. By cloning a lasB::lacZ fusion and a lasR gene under control of the lac promoter in Escherichia coli, we have developed a quantitative bioassay for PAI. We have used this assay to follow the purification of PAI from...

  8. Regulation of plasmid virulence gene expression in Salmonella dublin involves an unusual operon structure.

    OpenAIRE

    Krause, M.; Fang, F C; Guiney, D G

    1992-01-01

    The 80-kb plasmid pSDL2 of Salmonella dublin Lane is essential for lethal systemic infection in experimental mice. A cluster of five plasmid genes, designated spvR, spvA, spvB, spvC, and spvD, is sufficient to express the plasmid-related virulent phenotype. The spvR gene product has recently been identified as a positive regulator of spvB expression in the stationary phase of bacterial growth (F. C. Fang, M. Krause, C. Roudier, J. Fierer, and D. G. Guiney, J. Bacteriol. 173:6783-6789, 1991). ...

  9. Different distribution patterns of ten virulence genes in Legionella reference strains and strains isolated from environmental water and patients.

    Science.gov (United States)

    Zhan, Xiao-Yong; Hu, Chao-Hui; Zhu, Qing-Yi

    2016-04-01

    Virulence genes are distinct regions of DNA which are present in the genome of pathogenic bacteria and absent in nonpathogenic strains of the same or related species. Virulence genes are frequently associated with bacterial pathogenicity in genus Legionella. In the present study, an assay was performed to detect ten virulence genes, including iraA, iraB, lvrA, lvrB, lvhD, cpxR, cpxA, dotA, icmC and icmD in different pathogenicity islands of 47 Legionella reference strains, 235 environmental strains isolated from water, and 4 clinical strains isolated from the lung tissue of pneumonia patients. The distribution frequencies of these genes in reference or/and environmental L. pneumophila strains were much higher than those in reference non-L. pneumophila or/and environmental non-L. pneumophila strains, respectively. L. pneumophila clinical strains also maintained higher frequencies of these genes compared to four other types of Legionella strains. Distribution frequencies of these genes in reference L. pneumophila strains were similar to those in environmental L. pneumophila strains. In contrast, environmental non-L. pneumophila maintained higher frequencies of these genes compared to those found in reference non-L. pneumophila strains. This study illustrates the association of virulence genes with Legionella pathogenicity and reveals the possible virulence evolution of non-L. pneumophia strains isolated from environmental water. PMID:26757724

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

    OpenAIRE

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

    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 ...

  11. Natural Selection in Virulence Genes of Francisella tularensis.

    Science.gov (United States)

    Gunnell, Mark K; Robison, Richard A; Adams, Byron J

    2016-06-01

    A fundamental tenet of evolution is that alleles that are under negative selection are often deleterious and confer no evolutionary advantage. Negatively selected alleles are removed from the gene pool and are eventually extinguished from the population. Conversely, alleles under positive selection do confer an evolutionary advantage and lead to an increase in the overall fitness of the organism. These alleles increase in frequency until they eventually become fixed in the population. Francisella tularensis is a zoonotic pathogen and a potential biothreat agent. The most virulent type of F. tularensis, Type A, is distributed across North America with Type A.I occurring mainly in the east and Type A.II appearing mainly in the west. F. tularensis is thought to be a genome in decay (losing genes) because of the relatively large number of pseudogenes present in its genome. We hypothesized that the observed frequency of gene loss/pseudogenes may be an artifact of evolution in response to a changing environment, and that genes involved in virulence should be under strong positive selection. To test this hypothesis, we sequenced and compared whole genomes of Type A.I and A.II isolates. We analyzed a subset of virulence and housekeeping genes from several F. tularensis subspecies genomes to ascertain the presence and extent of positive selection. Eleven previously identified virulence genes were screened for positive selection along with 10 housekeeping genes. Analyses of selection yielded one housekeeping gene and 7 virulence genes which showed significant evidence of positive selection at loci implicated in cell surface structures and membrane proteins, metabolism and biosynthesis, transcription, translation and cell separation, and substrate binding and transport. Our results suggest that while the loss of functional genes through disuse could be accelerated by negative selection, the genome decay in Francisella could also be the byproduct of adaptive evolution

  12. Helicobacter pylori HP0231 Influences Bacterial Virulence and Is Essential for Gastric Colonization

    Science.gov (United States)

    Zhong, Yu; Anderl, Florian; Kruse, Tobias; Schindele, Franziska; Jagusztyn-Krynicka, Elżbieta Katarzyna; Fischer, Wolfgang; Gerhard, Markus

    2016-01-01

    The Dsb protein family is responsible for introducing disulfide bonds into nascent proteins in prokaryotes, stabilizing the structure of many proteins. Helicobacter pylori HP0231 is a Dsb-like protein, shown to catalyze disulfide bond formation and to participate in redox homeostasis. Notably, many H. pylori virulence factors are stabilized by the formation of disulfide bonds. By employing H. pylori HP0231 deficient strains we analyzed the effect of lack of this bacterial protein on the functionality of virulence factors containing putative disulfide bonds. The lack of H. pylori HP0231 impaired CagA translocation into gastric epithelial cells and reduced VacA-induced cellular vacuolation. Moreover, H. pylori HP0231 deficient bacteria were not able to colonize the gastric mucosa of mice, probably due to compromised motility. Together, our data demonstrate an essential function for H. pylori HP0231 in gastric colonization and proper function of bacterial virulence factors related to gastric pathology. PMID:27138472

  13. Prediction of Bacterial Virulent Proteins with Composition Moment Vector Feature Encoding Method

    Directory of Open Access Journals (Sweden)

    Gök Murat

    2016-01-01

    Full Text Available Prediction of bacterial virulent proteins is critical for vaccine development and understanding of virulence mechanisms in pathogens. For this purpose, a number of feature encoding methods based on sequences and evolutionary information of a given protein have been proposed and applied with some classifier algorithms so far. In this paper, we performed composition moment vector (CMV, which includes information about both composition and position of amino acid in the protein sequence to predict bacterial virulent proteins. The tests were validated in three different independent datasets. Experimental results show that CMV feature encoding method leads to better classification performance in terms of accuracy, sensitivity, f-measure and the Matthews correlation coefficient (MCC scores on diverse classifiers.

  14. Method for Screening Compounds That Influence Virulence Gene Expression in Staphylococcus aureus

    DEFF Research Database (Denmark)

    Nielsen, A.; Nielsen, Kristian Fog; Frees, D.; Larsen, Thomas Ostenfeld; Ingmer, H.

    2010-01-01

    We present a simple assay to examine effects of compounds on virulence gene expression in the human pathogen Staphylococcus aureus. The assay employs transcriptional reporter strains carrying lacZ fused to central virulence genes. Compounds affecting virulence gene expression and activity of the...

  15. Bacteriophage-encoded shiga toxin gene in atypical bacterial host

    Directory of Open Access Journals (Sweden)

    Casas Veronica

    2011-07-01

    Full Text Available Abstract Background Contamination from fecal bacteria in recreational waters is a major health concern since bacteria capable of causing human disease can be found in animal feces. The Dog Beach area of Ocean Beach in San Diego, California is a beach prone to closures due to high levels of fecal indicator bacteria (FIB. A potential source of these FIB could be the canine feces left behind by owners who do not clean up after their pets. We tested this hypothesis by screening the DNA isolated from canine feces for the bacteriophage-encoded stx gene normally found in the virulent strains of the fecal bacterium Escherichia coli. Results Twenty canine fecal samples were collected, processed for total and bacterial fraction DNA, and screened by PCR for the stx gene. The stx gene was detected in the total and bacterial fraction DNA of one fecal sample. Bacterial isolates were then cultivated from the stx-positive fecal sample. Eighty nine of these canine fecal bacterial isolates were screened by PCR for the stx gene. The stx gene was detected in five of these isolates. Sequencing and phylogenetic analyses of 16S rRNA gene PCR products from the canine fecal bacterial isolates indicated that they were Enterococcus and not E. coli. Conclusions The bacteriophage-encoded stx gene was found in multiple species of bacteria cultivated from canine fecal samples gathered at the shoreline of the Dog Beach area of Ocean Beach in San Diego, California. The canine fecal bacteria carrying the stx gene were not the typical E. coli host and were instead identified through phylogenetic analyses as Enterococcus. This suggests a large degree of horizontal gene transfer of exotoxin genes in recreational waters.

  16. ``Black Holes" and Bacterial Pathogenicity: A Large Genomic Deletion that Enhances the Virulence of Shigella spp. and Enteroinvasive Escherichia coli

    Science.gov (United States)

    Maurelli, Anthony T.; Fernandez, Reinaldo E.; Bloch, Craig A.; Rode, Christopher K.; Fasano, Alessio

    1998-03-01

    Plasmids, bacteriophages, and pathogenicity islands are genomic additions that contribute to the evolution of bacterial pathogens. For example, Shigella spp., the causative agents of bacillary dysentery, differ from the closely related commensal Escherichia coli in the presence of a plasmid in Shigella that encodes virulence functions. However, pathogenic bacteria also may lack properties that are characteristic of nonpathogens. Lysine decarboxylate (LDC) activity is present in ≈ 90% of E. coli strains but is uniformly absent in Shigella strains. When the gene for LDC, cadA, was introduced into Shigella flexneri 2a, virulence became attenuated, and enterotoxin activity was inhibited greatly. The enterotoxin inhibitor was identified as cadaverine, a product of the reaction catalyzed by LDC. Comparison of the S. flexneri 2a and laboratory E. coli K-12 genomes in the region of cadA revealed a large deletion in Shigella. Representative strains of Shigella spp. and enteroinvasive E. coli displayed similar deletions of cadA. Our results suggest that, as Shigella spp. evolved from E. coli to become pathogens, they not only acquired virulence genes on a plasmid but also shed genes via deletions. The formation of these ``black holes,'' deletions of genes that are detrimental to a pathogenic lifestyle, provides an evolutionary pathway that enables a pathogen to enhance virulence. Furthermore, the demonstration that cadaverine can inhibit enterotoxin activity may lead to more general models about toxin activity or entry into cells and suggests an avenue for antitoxin therapy. Thus, understanding the role of black holes in pathogen evolution may yield clues to new treatments of infectious diseases.

  17. The use of transpositional mutagenesis to study bacterial virulence

    International Nuclear Information System (INIS)

    Extracellular protease of A. hydrophila was shown to be lethal factor for fish. Protease deficient mutants were obtained from A. hydrophila strain 79. A. hydrophila was mutagenized by inserting Tn10 (tetracycline resistance factor) into the chromosome. This was achieved by conjugation between A. hydrophila and E. coli which contains Tn10 carried on the suicide vector pRK2013. Virulence of the protease deficient mutants was determined by injecting into channel catfish and comparing the mortalities produced by the mutants to that produced by the wild type strain. Protease deficient isolates were non virulent when inoculated into channel catfish (compared to the wild type strain). Proteolytic activities of some protease deficient isolates were compared to the activities of the wild type strain using a quantitative plate technique. The following substrates were used to study the proteolytic activities: casein, gelatin, elastin, staphylococcus and klebsiella. Loss of the proteolytic activity of caseinase, gelatinase and elastase was associated with the loss of virulence of A. hydrophila. Acquiring the DNA from the media was studied using a new transformation technique; no artificial competence was provided. A strain of Escherchi coli, Edwardsiella ictaluri, and Aeromonas hydrophila acquired antibiotic resistance markers when they were grown on media containing the target antibiotic and the resistance markers. When homologous and heterologous 32P-labelled DNA were supplied to growing cultures of A. hydrophila, A. hydrophila cells and their chromosomes were found labelled. Total cellular radioactivity of the culture receiving heterologous labelled DNA was higher than the culture receiving homologous DNA; however the chromosomal radioactivity was on the opposite where it was higher in case of the culture receiving homologous DNA

  18. Applying the ResFinder and VirulenceFinder web-services for easy identification of acquired antibiotic resistance and E. coli virulence genes in bacteriophage and prophage nucleotide sequences

    DEFF Research Database (Denmark)

    Kleinheinz, Kortine Annina; Joensen, Katrine Grimstrup; Larsen, Mette Voldby

    2014-01-01

    these tools, ResFinder and VirulenceFinder, can be used to identify acquired antibiotic resistance and virulence genes in phage genomes of interest. The general applicability of the tools is demonstrated on data sets of 1,642 phage genomes and 1,442 predicted prophages.......Extensive research is currently being conducted on the use of bacteriophages for applications in human medicine, agriculture and food manufacturing. However, phages are important vehicles of horisontal gene transfer and play a significant role in bacterial evolution. As a result, concern has been...... raised that this increased use and dissemination of phages could result in spread of deleterious genes, e.g., antibiotic resistance and virulence genes. Meanwhile, in the wake of the genomic era, several tools have been developed for characterization of bacterial genomes. Here we describe how two of...

  19. Homeostatic interplay between bacterial cell-cell signaling and iron in virulence.

    Directory of Open Access Journals (Sweden)

    Ronen Hazan

    2010-03-01

    Full Text Available Pathogenic bacteria use interconnected multi-layered regulatory networks, such as quorum sensing (QS networks to sense and respond to environmental cues and external and internal bacterial cell signals, and thereby adapt to and exploit target hosts. Despite the many advances that have been made in understanding QS regulation, little is known regarding how these inputs are integrated and processed in the context of multi-layered QS regulatory networks. Here we report the examination of the Pseudomonas aeruginosa QS 4-hydroxy-2-alkylquinolines (HAQs MvfR regulatory network and determination of its interaction with the QS acyl-homoserine-lactone (AHL RhlR network. The aim of this work was to elucidate paradigmatically the complex relationships between multi-layered regulatory QS circuitries, their signaling molecules, and the environmental cues to which they respond. Our findings revealed positive and negative homeostatic regulatory loops that fine-tune the MvfR regulon via a multi-layered dependent homeostatic regulation of the cell-cell signaling molecules PQS and HHQ, and interplay between these molecules and iron. We discovered that the MvfR regulon component PqsE is a key mediator in orchestrating this homeostatic regulation, and in establishing a connection to the QS rhlR system in cooperation with RhlR. Our results show that P. aeruginosa modulates the intensity of its virulence response, at least in part, through this multi-layered interplay. Our findings underscore the importance of the homeostatic interplay that balances competition within and between QS systems via cell-cell signaling molecules and environmental cues in the control of virulence gene expression. Elucidation of the fine-tuning of this complex relationship offers novel insights into the regulation of these systems and may inform strategies designed to limit infections caused by P. aeruginosa and related human pathogens.

  20. Engineered bacterial communication prevents Vibrio cholerae virulence in an infant mouse model

    OpenAIRE

    Duan, Faping; March, John C.

    2010-01-01

    To investigate the possibility of using commensal bacteria as signal mediators for inhibiting the disease cholera, we stably transformed Escherichia coli Nissle 1917 (Nissle) to express the autoinducer molecule cholera autoinducer 1 (CAI-1) (shown previously to prevent virulence when present with another signaling molecule, autoinducer 2, at high concentrations) and determined the effect on Vibrio cholerae virulence gene expression and colonization in an infant mouse model. We found that pret...

  1. Development and application of the active surveillance of pathogens microarray to monitor bacterial gene flux

    Directory of Open Access Journals (Sweden)

    Hinds Jason

    2008-10-01

    Full Text Available Abstract Background Human and animal health is constantly under threat by emerging pathogens that have recently acquired genetic determinants that enhance their survival, transmissibility and virulence. We describe the construction and development of an Active Surveillance of Pathogens (ASP oligonucleotide microarray, designed to 'actively survey' the genome of a given bacterial pathogen for virulence-associated genes. Results The microarray consists of 4958 reporters from 151 bacterial species and include genes for the identification of individual bacterial species as well as mobile genetic elements (transposons, plasmid and phage, virulence genes and antibiotic resistance genes. The ASP microarray was validated with nineteen bacterial pathogens species, including Francisella tularensis, Clostridium difficile, Staphylococcus aureus, Enterococcus faecium and Stenotrophomonas maltophilia. The ASP microarray identified these bacteria, and provided information on potential antibiotic resistance (eg sufamethoxazole resistance and sulfonamide resistance and virulence determinants including genes likely to be acquired by horizontal gene transfer (e.g. an alpha-haemolysin. Conclusion The ASP microarray has potential in the clinic as a diagnostic tool, as a research tool for both known and emerging pathogens, and as an early warning system for pathogenic bacteria that have been recently modified either naturally or deliberately.

  2. Helicobacter pylori virulence genes and microevolution in host and the clinical outcome: review article

    Directory of Open Access Journals (Sweden)

    Seyedeh Zahra Bakhti

    2014-12-01

    Full Text Available Helicobacter pylori (H. pylori is the causative agent in development of gastroduode-nal diseases, such as chronic atrophic gastritis, peptic ulcers, mucosa associated lym-phoid tissue (MALT lymphoma, and gastric cancer. H. pylori has been associated with inflammation in cardia, showing the fact that infection with this bacterium could also be a risk factor for gastric cardia cancer. Gastric cancer is the fourth most common cancer worldwide. This is the second leading cause of cancer-related deaths, and ap-proximately 700,000 people succumb each year to gastric adenocarcinoma. It has been estimated that 69% of the Iranian population currently harbor H. pylori infection. The prevalence of duodenal ulcer and gastric cancer is high in Iranian populations. However, this has been largely influenced by geographic and/or ethnic origin. Epidemi-ology studies have shown that host, environmental, and bacterial factors determine the outcome of H. pylori infection. The bacterium contains allelic diversity and high genet-ic variability into core- and virulence-genes and that this diversity is geographically and ethnically structured. The genetic diversity within H. pylori is greater than within most other bacteria, and its diversity is more than 50-fold higher than that of human DNA. The maintenance of high diversification makes this bacterium to cope with particular challenges in individual hosts. It has been reported that the recombination contributed to the creation of new genes and gene family. Furthermore, the microevolution in cagA and vacA genes is a common event, leading to a change in the virulence phenotype. These factors contribute to the bacterial survival in acidic conditions in stomach and protect it from host immune system, causing tissue damage and clinical disease. In this review article, we discussed the correlation between H. pylori virulence factors and clin-ical outcomes, microevolution of H. pylori virulence genes in a single host

  3. Genes involved in virulence of the entomopathogenic fungus Beauveria bassiana.

    Science.gov (United States)

    Valero-Jiménez, Claudio A; Wiegers, Harm; Zwaan, Bas J; Koenraadt, Constantianus J M; van Kan, Jan A L

    2016-01-01

    Pest insects cause severe damage to global crop production and pose a threat to human health by transmitting diseases. Traditionally, chemical pesticides (insecticides) have been used to control such pests and have proven to be effective only for a limited amount of time because of the rapid spread of genetic insecticide resistance. The basis of this resistance is mostly caused by (co)dominant mutations in single genes, which explains why insecticide use alone is an unsustainable solution. Therefore, robust solutions for insect pest control need to be sought in alternative methods such as biological control agents for which single-gene resistance is less likely to evolve. The entomopathogenic fungus Beauveria bassiana has shown potential as a biological control agent of insects, and insight into the mechanisms of virulence is essential to show the robustness of its use. With the recent availability of the whole genome sequence of B. bassiana, progress in understanding the genetics that constitute virulence toward insects can be made more quickly. In this review we divide the infection process into distinct steps and provide an overview of what is currently known about genes and mechanisms influencing virulence in B. bassiana. We also discuss the need for novel strategies and experimental methods to better understand the infection mechanisms deployed by entomopathogenic fungi. Such knowledge can help improve biocontrol agents, not only by selecting the most virulent genotypes, but also by selecting the genotypes that use combinations of virulence mechanisms for which resistance in the insect host is least likely to develop. PMID:26628209

  4. Genome sequence of Brucella abortus vaccine strain S19 compared to virulent strains yields candidate virulence genes.

    Science.gov (United States)

    Crasta, Oswald R; Folkerts, Otto; Fei, Zhangjun; Mane, Shrinivasrao P; Evans, Clive; Martino-Catt, Susan; Bricker, Betsy; Yu, GongXin; Du, Lei; Sobral, Bruno W

    2008-01-01

    The Brucella abortus strain S19, a spontaneously attenuated strain, has been used as a vaccine strain in vaccination of cattle against brucellosis for six decades. Despite many studies, the physiological and molecular mechanisms causing the attenuation are not known. We have applied pyrosequencing technology together with conventional sequencing to rapidly and comprehensively determine the complete genome sequence of the attenuated Brucella abortus vaccine strain S19. The main goal of this study is to identify candidate virulence genes by systematic comparative analysis of the attenuated strain with the published genome sequences of two virulent and closely related strains of B. abortus, 9-941 and 2308. The two S19 chromosomes are 2,122,487 and 1,161,449 bp in length. A total of 3062 genes were identified and annotated. Pairwise and reciprocal genome comparisons resulted in a total of 263 genes that were non-identical between the S19 genome and any of the two virulent strains. Amongst these, 45 genes were consistently different between the attenuated strain and the two virulent strains but were identical amongst the virulent strains, which included only two of the 236 genes that have been implicated as virulence factors in literature. The functional analyses of the differences have revealed a total of 24 genes that may be associated with the loss of virulence in S19. Of particular relevance are four genes with more than 60 bp consistent difference in S19 compared to both the virulent strains, which, in the virulent strains, encode an outer membrane protein and three proteins involved in erythritol uptake or metabolism. PMID:18478107

  5. Genome sequence of Brucella abortus vaccine strain S19 compared to virulent strains yields candidate virulence genes.

    Directory of Open Access Journals (Sweden)

    Oswald R Crasta

    Full Text Available The Brucella abortus strain S19, a spontaneously attenuated strain, has been used as a vaccine strain in vaccination of cattle against brucellosis for six decades. Despite many studies, the physiological and molecular mechanisms causing the attenuation are not known. We have applied pyrosequencing technology together with conventional sequencing to rapidly and comprehensively determine the complete genome sequence of the attenuated Brucella abortus vaccine strain S19. The main goal of this study is to identify candidate virulence genes by systematic comparative analysis of the attenuated strain with the published genome sequences of two virulent and closely related strains of B. abortus, 9-941 and 2308. The two S19 chromosomes are 2,122,487 and 1,161,449 bp in length. A total of 3062 genes were identified and annotated. Pairwise and reciprocal genome comparisons resulted in a total of 263 genes that were non-identical between the S19 genome and any of the two virulent strains. Amongst these, 45 genes were consistently different between the attenuated strain and the two virulent strains but were identical amongst the virulent strains, which included only two of the 236 genes that have been implicated as virulence factors in literature. The functional analyses of the differences have revealed a total of 24 genes that may be associated with the loss of virulence in S19. Of particular relevance are four genes with more than 60 bp consistent difference in S19 compared to both the virulent strains, which, in the virulent strains, encode an outer membrane protein and three proteins involved in erythritol uptake or metabolism.

  6. Growth of Yersinia pseudotuberculosis in human plasma: impacts on virulence and metabolic gene expression

    Science.gov (United States)

    Rosso, Marie-Laure; Chauvaux, Sylvie; Dessein, Rodrigue; Laurans, Caroline; Frangeul, Lionel; Lacroix, Céline; Schiavo, Angèle; Dillies, Marie-Agnès; Foulon, Jeannine; Coppée, Jean-Yves; Médigue, Claudine; Carniel, Elisabeth; Simonet, Michel; Marceau, Michaël

    2008-01-01

    Background In man, infection by the Gram-negative enteropathogen Yersinia pseudotuberculosis is usually limited to the terminal ileum. However, in immunocompromised patients, the microorganism may disseminate from the digestive tract and thus cause a systemic infection with septicemia. Results To gain insight into the metabolic pathways and virulence factors expressed by the bacterium at the blood stage of pseudotuberculosis, we compared the overall gene transcription patterns (the transcriptome) of bacterial cells cultured in either human plasma or Luria-Bertani medium. The most marked plasma-triggered metabolic consequence in Y. pseudotuberculosis was the switch to high glucose consumption, which is reminiscent of the acetogenic pathway (known as "glucose overflow") in Escherichia coli. However, upregulation of the glyoxylate shunt enzymes suggests that (in contrast to E. coli) acetate may be further metabolized in Y. pseudotuberculosis. Our data also indicate that the bloodstream environment can regulate major virulence genes (positively or negatively); the yadA adhesin gene and most of the transcriptional units of the pYV-encoded type III secretion apparatus were found to be upregulated, whereas transcription of the pH6 antigen locus was strongly repressed. Conclusion Our results suggest that plasma growth of Y. pseudotuberculosis is responsible for major transcriptional regulatory events and prompts key metabolic reorientations within the bacterium, which may in turn have an impact on virulence. PMID:19055764

  7. Growth of Yersinia pseudotuberculosis in human plasma: impacts on virulence and metabolic gene expression

    Directory of Open Access Journals (Sweden)

    Coppée Jean-Yves

    2008-12-01

    Full Text Available Abstract Background In man, infection by the Gram-negative enteropathogen Yersinia pseudotuberculosis is usually limited to the terminal ileum. However, in immunocompromised patients, the microorganism may disseminate from the digestive tract and thus cause a systemic infection with septicemia. Results To gain insight into the metabolic pathways and virulence factors expressed by the bacterium at the blood stage of pseudotuberculosis, we compared the overall gene transcription patterns (the transcriptome of bacterial cells cultured in either human plasma or Luria-Bertani medium. The most marked plasma-triggered metabolic consequence in Y. pseudotuberculosis was the switch to high glucose consumption, which is reminiscent of the acetogenic pathway (known as "glucose overflow" in Escherichia coli. However, upregulation of the glyoxylate shunt enzymes suggests that (in contrast to E. coli acetate may be further metabolized in Y. pseudotuberculosis. Our data also indicate that the bloodstream environment can regulate major virulence genes (positively or negatively; the yadA adhesin gene and most of the transcriptional units of the pYV-encoded type III secretion apparatus were found to be upregulated, whereas transcription of the pH6 antigen locus was strongly repressed. Conclusion Our results suggest that plasma growth of Y. pseudotuberculosis is responsible for major transcriptional regulatory events and prompts key metabolic reorientations within the bacterium, which may in turn have an impact on virulence.

  8. Patterns of virulence gene expression differ between biofilm and tissue communities of Streptococcus pyogenes.

    Science.gov (United States)

    Cho, Kyu Hong; Caparon, Michael G

    2005-09-01

    The ability of Streptococcus pyogenes to form biofilm-like bacterial communities during infection of soft tissue has suggested that the capacity to produce biofilm may be important for pathogenesis. To examine this relationship, a panel of mutants was evaluated for their ability to form biofilm on abiotic surfaces in several assays. Several established virulence factors were crucial for biofilm formation, including the M protein, required for initial cell-surface interactions, and the hyaluronic acid capsule, required for subsequent maturation into a three-dimensional structure. Mutants lacking the transcription regulators Mga and CovR (CsrR) also failed to form biofilm. Comparison of transcriptional profiles revealed differential regulation of approximately 25% of the genome upon adaptation to biofilm. During infection of zebrafish, several virulence factors (notably cysteine protease and streptokinase) were regulated in a biofilm-like manner. However, the overall profile of virulence factor expression indicated that tissue communities have a pattern of gene expression different from biofilm. Taken together, these data show that while biofilm and tissue communities have many characteristics in common, that biofilm reproduces only a subset of the myriad cues used by tissue communities for regulation of virulence. PMID:16135223

  9. Bacterial Ortholog of Mammalian Translocator Protein (TSPO) with Virulence Regulating Activity

    Science.gov (United States)

    Chapalain, Annelise; Chevalier, Sylvie; Orange, Nicole; Murillo, Laurence; Papadopoulos, Vassilios; Feuilloley, Marc G. J.

    2009-01-01

    The translocator protein (TSPO), previously designated as peripheral-type benzodiazepine receptor, is a protein mainly located in the outer mitochondrial membrane of eukaryotic cells. TSPO is implicated in major physiological functions and functionally associated with other proteins such as the voltage-dependent anionic channel, also designated as mitochondrial porin. Surprisingly, a TSPO-related protein was identified in the photosynthetic bacterium Rhodobacter sphaeroides but it was initially considered as a relict of evolution. In the present study we cloned a tspO gene in Pseudomonas fluorescens MF37, a non-photosynthetic eubacterium and we used bioinformatics tools to identify TSPO in the genome of 97 other bacteria. P. fluorescens TSPO was recognized by antibodies against mouse protein and by PK 11195, an artificial ligand of mitochondrial TSPO. As in eukaryotes, bacterial TSPO appears functionally organized as a dimer and the apparent Kd for PK 11195 is in the same range than for its eukaryotic counterpart. When P. fluorescens MF37 was treated with PK 11195 (10−5 M) adhesion to living or artificial surfaces and biofilm formation activity were increased. Conversely, the apoptotic potential of bacteria on eukaryotic cells was significantly reduced. This effect of PK11195 was abolished in a mutant of P. fluorescens MF37 deficient for its major outer membrane porin, OprF. The present results demonstrate the existence of a bacterial TSPO that shares common structural and functional characteristics with its mammalian counterpart. This protein, apparently involved in adhesion and virulence, reveals the existence of a possible new inter kingdom signalling system and suggests that the human microbiome should be involuntarily exposed to the evolutionary pressure of benzodiazepines and related molecules. This discovery also represents a promising opportunity for the development of alternative antibacterial strategies. PMID:19564920

  10. Bacterial ortholog of mammalian translocator protein (TSPO with virulence regulating activity.

    Directory of Open Access Journals (Sweden)

    Annelise Chapalain

    Full Text Available The translocator protein (TSPO, previously designated as peripheral-type benzodiazepine receptor, is a protein mainly located in the outer mitochondrial membrane of eukaryotic cells. TSPO is implicated in major physiological functions and functionally associated with other proteins such as the voltage-dependent anionic channel, also designated as mitochondrial porin. Surprisingly, a TSPO-related protein was identified in the photosynthetic bacterium Rhodobacter sphaeroides but it was initially considered as a relict of evolution. In the present study we cloned a tspO gene in Pseudomonas fluorescens MF37, a non-photosynthetic eubacterium and we used bioinformatics tools to identify TSPO in the genome of 97 other bacteria. P. fluorescens TSPO was recognized by antibodies against mouse protein and by PK 11195, an artificial ligand of mitochondrial TSPO. As in eukaryotes, bacterial TSPO appears functionally organized as a dimer and the apparent Kd for PK 11195 is in the same range than for its eukaryotic counterpart. When P. fluorescens MF37 was treated with PK 11195 (10(-5 M adhesion to living or artificial surfaces and biofilm formation activity were increased. Conversely, the apoptotic potential of bacteria on eukaryotic cells was significantly reduced. This effect of PK11195 was abolished in a mutant of P. fluorescens MF37 deficient for its major outer membrane porin, OprF. The present results demonstrate the existence of a bacterial TSPO that shares common structural and functional characteristics with its mammalian counterpart. This protein, apparently involved in adhesion and virulence, reveals the existence of a possible new inter kingdom signalling system and suggests that the human microbiome should be involuntarily exposed to the evolutionary pressure of benzodiazepines and related molecules. This discovery also represents a promising opportunity for the development of alternative antibacterial strategies.

  11. Bacterial ortholog of mammalian translocator protein (TSPO) with virulence regulating activity.

    Science.gov (United States)

    Chapalain, Annelise; Chevalier, Sylvie; Orange, Nicole; Murillo, Laurence; Papadopoulos, Vassilios; Feuilloley, Marc G J

    2009-01-01

    The translocator protein (TSPO), previously designated as peripheral-type benzodiazepine receptor, is a protein mainly located in the outer mitochondrial membrane of eukaryotic cells. TSPO is implicated in major physiological functions and functionally associated with other proteins such as the voltage-dependent anionic channel, also designated as mitochondrial porin. Surprisingly, a TSPO-related protein was identified in the photosynthetic bacterium Rhodobacter sphaeroides but it was initially considered as a relict of evolution. In the present study we cloned a tspO gene in Pseudomonas fluorescens MF37, a non-photosynthetic eubacterium and we used bioinformatics tools to identify TSPO in the genome of 97 other bacteria. P. fluorescens TSPO was recognized by antibodies against mouse protein and by PK 11195, an artificial ligand of mitochondrial TSPO. As in eukaryotes, bacterial TSPO appears functionally organized as a dimer and the apparent Kd for PK 11195 is in the same range than for its eukaryotic counterpart. When P. fluorescens MF37 was treated with PK 11195 (10(-5) M) adhesion to living or artificial surfaces and biofilm formation activity were increased. Conversely, the apoptotic potential of bacteria on eukaryotic cells was significantly reduced. This effect of PK11195 was abolished in a mutant of P. fluorescens MF37 deficient for its major outer membrane porin, OprF. The present results demonstrate the existence of a bacterial TSPO that shares common structural and functional characteristics with its mammalian counterpart. This protein, apparently involved in adhesion and virulence, reveals the existence of a possible new inter kingdom signalling system and suggests that the human microbiome should be involuntarily exposed to the evolutionary pressure of benzodiazepines and related molecules. This discovery also represents a promising opportunity for the development of alternative antibacterial strategies. PMID:19564920

  12. Differential transcription of virulence genes in Aggregatibacter actinomycetemcomitans serotypes

    OpenAIRE

    Marcia Pinto Alves MAYER; Umeda, Josely Emiko; Priscila Larcher LONGO; Simionato, Maria Regina Lorenzetti

    2013-01-01

    Background: Aggregatibacter actinomycetemcomitans serotypes are clearly associated with periodontitis or health, which suggests distinct strategies for survival within the host.Objective: We investigated the transcription profile of virulence-associated genes in A. actinomycetemcomitans serotype b (JP2 and SUNY 465) strains associated with disease and serotype a (ATCC 29523) strain associated with health. Design: Bacteria were co-cultured with immortalized gingival epithelial cells (OBA-9). T...

  13. Gene deletion strategy to examine the involvement of the two chondroitin lyases in Flavobacterium columnare virulence.

    Science.gov (United States)

    Li, Nan; Qin, Ting; Zhang, Xiao Lin; Huang, Bei; Liu, Zhi Xin; Xie, Hai Xia; Zhang, Jin; McBride, Mark J; Nie, Pin

    2015-11-01

    Flavobacterium columnare is an important bacterial pathogen of freshwater fish that causes high mortality of infected fish and heavy economic losses in aquaculture. The pathogenesis of this bacterium is poorly understood, in part due to the lack of efficient methods for genetic manipulation. In this study, a gene deletion strategy was developed and used to determine the relationship between the production of chondroitin lyases and virulence. The F. johnsoniae ompA promoter (PompA) was fused to sacB to construct a counterselectable marker for F. columnare. F. columnare carrying PompA-sacB failed to grow on media containing 10% sucrose. A suicide vector carrying PompA-sacB was constructed, and a gene deletion strategy was developed. Using this approach, the chondroitin lyase-encoding genes, cslA and cslB, were deleted. The ΔcslA and ΔcslB mutants were both partially deficient in digestion of chondroitin sulfate A, whereas a double mutant (ΔcslA ΔcslB) was completely deficient in chondroitin lyase activity. Cells of F. columnare wild-type strain G4 and of the chondroitin lyase-deficient ΔcslA ΔcslB mutant exhibited similar levels of virulence toward grass carp in single-strain infections. Coinfections, however, revealed a competitive advantage for the wild type over the chondroitin lyase mutant. The results indicate that chondroitin lyases are not essential virulence factors of F. columnare but may contribute to the ability of the pathogen to compete and cause disease in natural infections. The gene deletion method developed in this study may be employed to investigate the virulence factors of this bacterium and may have wide application in many other members of the phylum Bacteroidetes. PMID:26253667

  14. The Genetic Diversity of Helicobacter pylori Virulence Genes Is Not Associated with Gastric Atrophy Progression

    Directory of Open Access Journals (Sweden)

    Kita,Masahide

    2013-04-01

    Full Text Available Atrophy of the gastric mucosa is a precursor of intestinal-type gastric cancer, and Helicobacter pylori infection causes atrophic gastritis. The aim of this study was to determine whether the genetic diversity of H. pylori virulence genes is associated with the development and progression of gastric atrophy in humans. We isolated and cultured H. pylori strains from patients with gastric ulcer and duodenal ulcer accompanied by atrophic gastritis in background mucosa. H. pylori strains were stored at -80℃ prior to the experiments being carried out. We analyzed iceA, babA, vacA, cagA, and cagE genes by PCR. The cagA gene was analyzed through sequencing of the C-terminal region containing the EPIYA motif, which is related to tyrosine phosphorylation. Severe atrophy was observed in patients with gastric ulcer. The major phenotype of the vacA gene was s1c/m1 (93オ. The cagA gene was detected in all strains. The cagE gene was not detected in 2 and 5 strains from the mild cases and severe cases, respectively. The major cagA EPIYA motif, which is amino acids repeat in the C terminus, was the A-B-D type (44 of 58 strains. The virulence genes were not statistically associated with the severity of atrophy in the background gastric mucosa in humans. Not only identification of bacterial virulence factors but also studies of the host response will be necessary to investigate the progression of gastric atrophy and subsequent cancer development in humans.

  15. Contribution of Escherichia coli Alpha-Hemolysin to Bacterial Virulence and to Intraperitoneal Alterations in Peritonitis

    OpenAIRE

    May, Addison K; Gleason, Thomas G.; Sawyer, Robert G.; Pruett, Timothy L.

    2000-01-01

    Alpha-hemolysin (Hly) is a common exotoxin produced by Escherichia coli that enhances virulence in a number of clinical infections. The addition of hemolysin production to laboratory bacterial strains is known to increase the lethality of E. coli peritonitis. However, the mechanisms involved have not been determined and the contribution of hemolysin to the alterations in the host intraperitoneal environment and the leukocyte response is not known. Utilizing a rat peritonitis model, we show th...

  16. Helicobacter pylori HP0231 Influences Bacterial Virulence and Is Essential for Gastric Colonization

    OpenAIRE

    Zhong, Yu; Anderl, Florian; Kruse, Tobias; Schindele, Franziska; Jagusztyn-Krynicka, Elżbieta Katarzyna; Fischer, Wolfgang; Gerhard, Markus; Mejías-Luque, Raquel

    2016-01-01

    The Dsb protein family is responsible for introducing disulfide bonds into nascent proteins in prokaryotes, stabilizing the structure of many proteins. Helicobacter pylori HP0231 is a Dsb-like protein, shown to catalyze disulfide bond formation and to participate in redox homeostasis. Notably, many H. pylori virulence factors are stabilized by the formation of disulfide bonds. By employing H. pylori HP0231 deficient strains we analyzed the effect of lack of this bacterial protein on the funct...

  17. Distribution of putative virulence genes and antimicrobial drug resistance in Vibrio harveyi

    Digital Repository Service at National Institute of Oceanography (India)

    Parvathi, A.; Mendez, D.; Anto, C.

    environments for understanding the distribution of putative virulence genes and antimicrobial drug resistance. The putative genes targeted for PCR detection included four reversible toxin (Rtx)/hemolysin genes, a gene encoding homologue of Vibrio cholerae...

  18. An Inner Membrane Protein (Imp) of Xanthomonas oryzae pv. oryzicola Functions in Carbon Acquisition, EPS Production, Bacterial Motility and Virulence in Rice

    Institute of Scientific and Technical Information of China (English)

    CHEN Gong-you

    2014-01-01

    Xanthomonas oryzae pv. oryzicola (Xoc) causes bacterial leaf streak, a devastating disease in rice-growing regions worldwide. A Tn5-insertion mutant in Xoc_3248, encoding an inner membrane protein (Imp), showed reduced virulence in rice. To explore the potential function of this gene in virulence, a deletion mutant R∆imp was constructed in the wild-type RS105. The R∆imp mutant was signiifcantly impaired for bacterial virulence and growth in planta. The mutation in imp made the pathogen insufifciently utilize glucose, fructose, mannose or pyruvate as a sole carbon source, leading to less extracellular polysaccharide (EPS) production and reduced motility. The deifciencies noted for the mutant were restored to wild-type levels when imp was introduced in trans. Transcription of imp was signiifcantly declined when hrpG and hrpX was mutated and the expression of hrpG and hrpX was also signiifcantly declined when imp was deleted. Cell sublocalization in planta showed Imp membrane-binding feature. These results suggest that Imp is a virulence factor with roles in the catabolism of sugars, EPS production, and bacterial motility.

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

    Directory of Open Access Journals (Sweden)

    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.

  20. The MogR Transcriptional Repressor Regulates Nonhierarchal Expression of Flagellar Motility Genes and Virulence in Listeria monocytogenes.

    Directory of Open Access Journals (Sweden)

    2006-04-01

    Full Text Available Flagella are surface structures critical for motility and virulence of many bacterial species. In Listeria monocytogenes, MogR tightly represses expression of flagellin (FlaA during extracellular growth at 37 degrees C and during intracellular infection. MogR is also required for full virulence in a murine model of infection. Using in vitro and in vivo infection models, we determined that the severe virulence defect of MogR-negative bacteria is due to overexpression of FlaA. Specifically, overproduction of FlaA in MogR-negative bacteria caused pleiotropic defects in bacterial division (chaining phenotype, intracellular spread, and virulence in mice. DNA binding and microarray analyses revealed that MogR represses transcription of all known flagellar motility genes by binding directly to a minimum of two TTTT-N(5-AAAA recognition sites positioned within promoter regions such that RNA polymerase binding is occluded. Analysis of MogR protein levels demonstrated that modulation of MogR repression activity confers the temperature-specificity to flagellar motility gene expression. Epistasis analysis revealed that MogR repression of transcription is antagonized in a temperature-dependent manner by the DegU response regulator and that DegU further regulates FlaA levels through a posttranscriptional mechanism. These studies provide the first known example to our knowledge of a transcriptional repressor functioning as a master regulator controlling nonhierarchal expression of flagellar motility genes.

  1. Differential expression of the virulence-associated protein p57 and characterization of its duplicated gene msa in virulent and attenuated strains of Renibacterium salmoninarum.

    Science.gov (United States)

    O'Farrell, C L; Strom, M S

    1999-11-01

    Virulence mechanisms utilized by the salmonid fish pathogen Renibacterium salmoninarum are poorly understood. One potential virulence factor is p57 (also designated MSA for major soluble antigen), an abundant 57 kDa soluble protein that is predominately localized on the bacterial cell surface with significant levels released into the extracellular milieu. Previous studies of an attenuated strain, MT 239, indicated that it differs from virulent strains in the amount of surface-associated p57. In this report, we show overall expression of p57 in R. salmoninarum MT 239 is considerably reduced as compared to a virulent strain, ATCC 33209. The amount of cell-associated p57 is decreased while the level of p57 in the culture supernatant is nearly equivalent between the strains. To determine if the lowered amount of cell-associated p57 was due to a sequence defect in p57, a genetic comparison was performed. Two copies of the gene encoding p57 (msa1 and msa2) were found in 33209 and MT 239, as well as in several other virulent isolates. Both copies from 33209 and MT 239 were cloned and sequenced and found to be identical to each other, and identical between the 2 strains. A comparison of msa1 and msa2 within each strain showed that their sequences diverge 40 base pairs 5' to the open reading frame, while sequences 3' to the open reading frame are essentially identical for at least 225 base pairs. Northern blot analysis showed no difference in steady state levels of msa mRNA between the 2 strains. These data suggest that while cell-surface localization of p57 may be important for R. salmoninarum virulence, the differences in localization and total p57 expression between 33209 and MT 239 are not due to differences in msa sequence or differences in steady state transcript levels. PMID:10598282

  2. Differential expression of the virulence-associated protein p57 and characterization of its duplicated gene rosa in virulent and attenuated strains of Renibacterium salmoninarum

    Science.gov (United States)

    O'Farrell, C. L.; Strom, M.S.

    1999-01-01

    Virulence mechanisms utilized by the salmonid fish pathogen Renibacterium salmoninarum are poorly understood. One potential virulence factor is p57 (also designated MSA for major soluble antigen), an abundant 57 kDa soluble protein that is predominately localized on the bacterial cell surface with significant levels released into the extracellular milieu. Previous studies of an attenuated strain, MT 239, indicated that it differs from virulent strains in the amount of surface-associated p57. In this report, we show overall expression of p57 in R. salmoninarum MT 239 is considerably reduced as compared to a virulent strain, ATCC 33209. The amount of cell-associated p57 is decreased while the level of p57 in the culture supernatant is nearly equivalent between the strains. To determine if lowered amount of cell-associated p57 was due to a sequence defect in p57, a genetic comparison was performed. Two copies of the gene encoding p57 (msa1 and msa2) were found in 33209 and MT 239, as well as in several other virulent isolates. Both copies from 33209 and MT 239 were cloned and sequenced and found to be identical to each other, and identical between the 2 strains. A comparison of msa1 and msa2 within each strain showed that their sequences diverge 40 base pairs 5, to the open reading frame, while sequences 3' to the open reading frame are essentially identical for at least 225 base pairs. Northern blot analysis showed no difference in steady state levels of rosa mRNA between the 2 strains. These data suggest that while cell-surface localization of p57 may be important for R. salmoninarum virulence, the differences in localization, and total p57 expression between 33209 anti MT 239 are not due to differences in rosa sequence or differences in steady state transcript levels.

  3. The extended spectrum β-lactamases (ESBL) and virulence genes of intestinal enteroaggregative Escherichia coli (EAEC) in healthy elderly individuals

    OpenAIRE

    Wang, Yuan; Wu, Jian; Cao, Yi

    2015-01-01

    Aim: to analyze the detection rate of intestinal enteroaggregative Escherichia coli (EAEC) in healthy elderly (≥60 years) individuals in the Hangzhou area of China, and to investigate the extended spectrum β-lactamases and virulence genes of EAEC. Methods: Stool specimens provided by healthy elderly individuals were cultured on blood agar, SS, and MAC plates. The bacterial strains were identified using Vitek-2 Compact automatic microorganism identification system and mass spectrometry. The re...

  4. Role for the Burkholderia pseudomallei Type Three Secretion System Cluster 1 bpscN Gene in Virulence

    OpenAIRE

    D'Cruze, Tanya; Gong, Lan; Treerat, Puthayalai; Ramm, Georg; John D Boyce; Prescott, Mark; Adler, Ben; Rodney J. Devenish

    2011-01-01

    Burkholderia pseudomallei, the causal agent of melioidosis, employs a number of virulence factors during its infection of mammalian cells. One such factor is the type three secretion system (TTSS), which is proposed to mediate the transport and secretion of bacterial effector molecules directly into host cells. The B. pseudomallei genome contains three TTSS gene clusters (designated TTSS1, TTSS2, and TTSS3). Previous research has indicated that neither TTSS1 nor TTSS2 is involved in B. pseudo...

  5. Fitness and virulence of a bacterial endoparasite in an environmentally stressed crustacean host.

    Science.gov (United States)

    Coors, Anja; De Meester, Luc

    2011-01-01

    Host-parasite interactions are shaped by the co-evolutionary arms race of parasite virulence, transmission success as well as host resistance and recovery. The virulence and fitness of parasites may depend on host condition, which is mediated, for instance, by host energy constraints. Here, we investigated to what extent stress imposed by predation threat and environmental pollutants influences host-parasite interactions. We challenged the crustacean host Daphnia magna with the sterilizing bacterial endoparasite Pasteuria ramosa and simultaneously exposed the host to fish kairomones, the pesticide carbaryl or both stressors. While parasite virulence, measured as impact on host mortality and sterilization, increased markedly after short-term pesticide exposure, it was not influenced by predation threat. Parasite fitness, measured in terms of produced transmission stages, decreased both in fish and pesticide treatments. This effect was much stronger under predation threat than carbaryl exposure, and was attributable to reduced somatic growth of the host, presumably resulting in fewer resources for parasite development. While the indirect impact of both stressors on spore loads provides evidence for host condition-dependent parasite fitness, the finding of increased virulence only under carbaryl exposure indicates a stronger physiological impact of the neurotoxic chemical compared with the effect of a non-toxic fish kairomone. PMID:20663250

  6. The importance of virulence prediction and gene networks in microbial risk assessment

    DEFF Research Database (Denmark)

    Wassenaar, Gertrude Maria; Gamieldien, Junaid; Shatkin, JoAnne;

    2007-01-01

    virulence genes from total genome sequences. The deterministic approach of considering gene function relating to an organism's pathogenicity has its limits. Gene function prediction based on sequence similarity is also not without flaws. Bioinformatic analysis can reveal virulence potential of a genome...

  7. Intercellular and intracellular signalling systems that globally control the expression of virulence genes in plant pathogenic bacteria.

    Science.gov (United States)

    Ham, Jong Hyun

    2013-04-01

    Plant pathogenic bacteria utilize complex signalling systems to control the expression of virulence genes at the cellular level and within populations. Quorum sensing (QS), an important intercellular communication mechanism, is mediated by different types of small molecules, including N-acyl homoserine lactones (AHLs), fatty acids and small proteins. AHL-mediated signalling systems dependent on the LuxI and LuxR family proteins play critical roles in the virulence of a wide range of Gram-negative plant pathogenic bacteria belonging to the Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria. Xanthomonas spp. and Xylella fastidiosa, members of the Gammaproteobacteria, however, possess QS systems that are mediated by fatty acid-type diffusible signal factors (DSFs). Recent studies have demonstrated that Ax21, a 194-amino-acid protein in Xanthomonas oryzae pv. oryzae, plays dual functions in activating a rice innate immune pathway through binding to the rice XA21 pattern recognition receptor and in regulating bacterial virulence and biofilm formation as a QS signal molecule. In xanthomonads, DSF-mediated QS systems are connected with the signalling pathways mediated by cyclic diguanosine monophosphate (c-di-GMP), which functions as a second messenger for the control of virulence gene expression in these bacterial pathogens. PMID:23186372

  8. Evaluating virulence of waterborne and clinical Aeromonas isolates using gene expression and mortality in neonatal mice followed by assessing cell culture’s ability to predict virulence based on transcriptional response

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, S L; Rodgers, M R; Lye, D J; Stelma, G N; McKinstry, Craig A.; Malard, Joel M.; Vesper, Sephen J.

    2007-10-01

    Aims: To assess the virulence of Aeromonas spp. using two models, a neonatal mouse assay and a mouse intestinal cell culture. Methods and Results: After artificial infection with a variety of Aeromonas spp., mRNA extracts from the two models were processed and hydridized to murine microarrays to determine host gene response. Definition of virulence was determined based on host mRNA production in murine neonatal intestinal tissue and mortality of infected animals. Infections of mouse intestinal cell cultures were then performed to determine whether this simpler model system’s mRNA responses correlated to neonatal results and therefore be predictive of virulence of Aeromonas spp. Virulent aeromonads up-regulated transcripts in both models including multiple host defense gene products (chemokines, regulation of transcription and apoptosis and cell signalling). Avirulent species exhibited little or no host response in neonates. Mortality results correlated well with both bacterial dose and average fold change of up-regulated transcripts in the neonatal mice. Conclusions: Cell culture results were less discriminating but showed promise as potentially being able to be predictive of virulence. Jun oncogene up-regulation in murine cell culture is potentially predictive of Aeromonas virulence. Significance and Impact of the Study: Having the ability to determine virulence of waterborne pathogens quickly would potentially assist public health officials to rapidly assess exposure risks.

  9. Detection of virulence genes in Malaysian Shigella species by multiplex PCR assay

    Directory of Open Access Journals (Sweden)

    Puthucheary SD

    2005-02-01

    Full Text Available Abstract Background In Malaysia, Shigella spp. was reported to be the third commonest bacterial agent responsible for childhood diarrhoea. Currently, isolation of the bacterium and confirmation of the disease by microbiological and biochemical methods remain as the "gold standard". This study aimed to detect the prevalence of four Shigella virulence genes present concurrently, in randomly selected Malaysian strains via a rapid multiplex PCR (mPCR assay. Methods A mPCR assay was designed for the simultaneous detection of chromosomal- and plasmid-encoded virulence genes (set1A, set1B, ial and ipaH in Shigella spp. One hundred and ten Malaysian strains (1997–2000 isolated from patients from various government hospitals were used. Reproducibility and sensitivity of the assay were also evaluated. Applicability of the mPCR in clinical settings was tested with spiked faeces following preincubation in brain heart infusion (BHI broth. Results The ipaH sequence was present in all the strains, while each of the set1A, set1B and ial gene was present in 40% of the strains tested. Reproducibility of the mPCR assay was 100% and none of the non-Shigella pathogens tested in this study were amplified. The mPCR could detect 100 colony-forming units (cfu of shigellae per reaction mixture in spiked faeces following preincubation. Conclusions The mPCR system is reproducible, sensitive and is able to identify pathogenic strains of shigellae irrespective of the locality of the virulence genes. It can be easily performed with a high throughput to give a presumptive identification of the causal pathogen.

  10. Role of bacterial γ-glutamyltranspeptidase as a novel virulence factor in bone-resorbing pathogenesis.

    Science.gov (United States)

    Kim, Jinmoon; Jang, Sungil; Kim, Aeryun; Su, Hanfu; Gunawardhana, Niluka; Jeon, Yeong-Eui; Bak, Eun Jung; Kim, Ji-Hye; Cha, Jeong-Heon

    2016-05-01

    Mammalian γ-glutamyltranspeptidase (GGT) has been identified as a bone-resorbing factor. Since GGT of Bacillus subtilis exhibits similarity in their primary structure and enzymatic characteristics with mammalian GGTs, the bone-resorbing activity of bacterial GGT was examined in this study. Osteoclastogenesis was performed in a co-culture system of mouse calvaria-derived osteoblasts and bone marrow cells. A conditioned medium from GGT-overproducing B. subtilis culture showed significantly higher activity of osteoclast formation than a conditioned medium from wild-type B. subtilis culture. Recombinant GGT (rGGT) of wild-type B. subtilis and an enzymatic activity-defected rGGT of B. subtilis 2288 mutant were expressed in Escherichia coli and purified using His tag. Both purified rGGTs induced similar levels of osteoclastogenesis, suggesting that B. subtilis GGT possesses virulent bone-resorbing activity and its activity is probably independent of its enzymatic activity. Furthermore, a recombinant protein of B. subtilis GGT heavy subunit (Bs rGGT/H) showed strong activity of osteoclastogenesis while the light subunit failed to show strong activity, suggesting that the bone-resorbing activity is mainly located at the heavy subunit. More importantly, the GGT enzymatic activity may not be required for this virulence activity since the light subunit contains the catalytic pocket. In addition, B. subtilis rGGT stimulated mRNA expressions of receptor activator of nuclear factor kappa-B ligand (RANKL) and cyclooxygenase-2 (COX-2), while an osteoprotegerin inhibited the osteoclast formation induced by Bs rGGT/H. This is the first demonstration that bacterial GGT itself is sufficient to act as a bone-resorbing virulence factor via RANKL-dependent pathway. Therefore, it can be hypothesized that GGT of periodontopathic bacteria may play an important role as a virulence factor in bone destruction. PMID:27095459

  11. Bacterial Quorum Sensing: Its Role in Virulence and Possibilities for Its Control

    OpenAIRE

    Rutherford, Steven T.; Bassler, Bonnie L

    2012-01-01

    Quorum sensing is a process of cell–cell communication that allows bacteria to share information about cell density and adjust gene expression accordingly. This process enables bacteria to express energetically expensive processes as a collective only when the impact of those processes on the environment or on a host will be maximized. Among the many traits controlled by quorum sensing is the expression of virulence factors by pathogenic bacteria. Here we review the quorum-sensing circuits of...

  12. Proteomics as a tool for studying bacterial virulence and antimicrobial resistance

    Directory of Open Access Journals (Sweden)

    Francisco José Pérez -Llarena

    2016-03-01

    Full Text Available Proteomic studies have improved our understanding of the microbial world. The most recent advances in this field have helped us to explore aspects beyond genomics. For example, by studying proteins and their regulation, researchers now understand how some pathogenic bacteria have adapted to the lethal actions of antibiotics. Proteomics has also advanced our knowledge of mechanisms of bacterial virulence and some important aspects of how bacteria interact with human cells and, thus, of the pathogenesis of infectious diseases. This review article addresses these issues in some of the most important human pathogens. It also reports some applications of MALDI-TOF mass spectrometry that may be important for the diagnosis of bacterial resistance in clinical laboratories in the future. The reported advances will enable new diagnostic and therapeutic strategies to be developed in the fight against some of the most lethal bacteria affecting humans.

  13. Influence of sublethal concentrations of common disinfectants on expression of virulence genes in Listeria monocytogenes

    DEFF Research Database (Denmark)

    Kastbjerg, Vicky Gaedt; Larsen, M. H.; Gram, Lone;

    2010-01-01

    routinely in the food industry affect the expression of different virulence genes in L. monocytogenes when added at sublethal concentrations. An agar-based assay was developed to screen the effect of disinfectants on virulence gene promoter expression and was validated at the transcriptional level by...... properties, such as antibiotic resistance....

  14. 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

    OpenAIRE

    Suat Moi Puah; Kek Heng Chua; Jin Ai Mary Anne Tan

    2016-01-01

    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 ...

  15. 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

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

    Science.gov (United States)

    Ziuzina, Dana; Boehm, Daniela; Patil, Sonal; Cullen, P. J.; Bourke, Paula

    2015-01-01

    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 for the

  17. Post-transcriptional gene regulation in the biology and virulence of Candida albicans.

    Science.gov (United States)

    Verma-Gaur, Jiyoti; Traven, Ana

    2016-06-01

    In the human fungal pathogen Candida albicans, remodelling of gene expression drives host adaptation and virulence. Recent studies revealed that in addition to transcription, post-transcriptional mRNA control plays important roles in virulence-related pathways. Hyphal morphogenesis, biofilm formation, stress responses, antifungal drug susceptibility and virulence in animal models require post-transcriptional regulators. This includes RNA binding proteins that control mRNA localization, decay and translation, as well as the cytoplasmic mRNA decay pathway. Comprehensive understanding of how modulation of gene expression networks drives C. albicans virulence will necessitate integration of our knowledge on transcriptional and post-transcriptional mRNA control. PMID:26999710

  18. Subinhibitory concentrations of antibiotics affect stress and virulence gene expression in Listeria monocytogenes and cause enhanced stress sensitivity but do not affect Caco‐2 cell invasion

    DEFF Research Database (Denmark)

    Knudsen, Gitte Maegaard; Holch, Anne; Gram, Lone

    2012-01-01

    Antibiotics can act as signal molecules and affect bacterial gene expression, physiology and virulence. The purpose of this study was to determine whether subinhibitory antibiotic concentrations alter gene expression and physiology of Listeria monocytogenes. Using an agar‐based screening assay with...... promoter fusions, 14 of 16 antibiotics induced or repressed expression of one or more stress and/or virulence genes. Despite ampicillin‐induced up‐regulation of PinlA‐lacZ expression, Caco‐2 cell invasion was not affected. Subinhibitory concentrations of ampicillin and tetracycline caused up‐ and down......‐regulation of stress response genes, respectively, but both antibiotics caused increased sensitivity to acid stress. Six combinations of gene‐antibiotic were quantified in broth cultures and five of the six resulted in the same expression pattern as the agar‐based assay. Antibiotics affect virulence and...

  19. Epigenetic Regulation of Virulence Gene Expression in Parasitic Protozoa.

    Science.gov (United States)

    Duraisingh, Manoj T; Horn, David

    2016-05-11

    Protozoan parasites colonize numerous metazoan hosts and insect vectors through their life cycles, with the need to respond quickly and reversibly while encountering diverse and often hostile ecological niches. To succeed, parasites must also persist within individuals until transmission between hosts is achieved. Several parasitic protozoa cause a huge burden of disease in humans and livestock, and here we focus on the parasites that cause malaria and African trypanosomiasis. Efforts to understand how these pathogens adapt to survive in varied host environments, cause disease, and transmit between hosts have revealed a wealth of epigenetic phenomena. Epigenetic switching mechanisms appear to be ideally suited for the regulation of clonal antigenic variation underlying successful parasitism. We review the molecular players and complex mechanistic layers that mediate the epigenetic regulation of virulence gene expression. Understanding epigenetic processes will aid the development of antiparasitic therapeutics. PMID:27173931

  20. Bacterial quorum sensing: its role in virulence and possibilities for its control.

    Science.gov (United States)

    Rutherford, Steven T; Bassler, Bonnie L

    2012-11-01

    Quorum sensing is a process of cell-cell communication that allows bacteria to share information about cell density and adjust gene expression accordingly. This process enables bacteria to express energetically expensive processes as a collective only when the impact of those processes on the environment or on a host will be maximized. Among the many traits controlled by quorum sensing is the expression of virulence factors by pathogenic bacteria. Here we review the quorum-sensing circuits of Staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa, and Vibrio cholerae. We outline these canonical quorum-sensing mechanisms and how each uniquely controls virulence factor production. Additionally, we examine recent efforts to inhibit quorum sensing in these pathogens with the goal of designing novel antimicrobial therapeutics. PMID:23125205

  1. Molecular identification and detection of virulence genes among Pseudomonas aeruginosa isolated from different infectious origins

    OpenAIRE

    Vajiheh Sadat Nikbin; Mohammad Mehdi Aslani; Marjan Hashemipour; Zeinab Sharafi; Fereshteh Shahcheraghi; Gholamhossein Ebrahimipour

    2012-01-01

    BACKGROUND AND OBJECTIVES: Pseudomonas aeruginosa possesses a variety of virulence factors that may contribute to its pathogenicity. The aim of this study was to evaluate oprI, oprL and toxA genes for PCR identification of clinical P. aeruginosa. In order to find out any relation between special virulence factors and special manifestation of P. aeruginosa infections, we detected virulence factors among these isolates by PCR. Ribotyping was used to evaluate the clonal relationship between stra...

  2. Pseudomonas corrugata crpCDE is part of the cyclic lipopeptide corpeptin biosynthetic gene cluster and is involved in bacterial virulence in tomato and in hypersensitive response in Nicotiana benthamiana

    NARCIS (Netherlands)

    Strano, C.P.; Bella, P.; Licciardello, G.; Fiore, A.; Piero, Lo A.R.; Fogliano, V.; Fogliano, V.; Catara, V.

    2015-01-01

    Pseudomonas corrugata CFBP 5454 produces two kinds of cyclic lipopeptides (CLPs), cormycin A and corpeptins, both of which possess surfactant, antimicrobial and phytotoxic activities. In this study, we identified genes coding for a putative non-ribosomal peptide synthetase and an ABC-type transport

  3. Ralstonia solanacearum Pectin Methylesterase Is Required for Growth on Methylated Pectin but Not for Bacterial Wilt Virulence

    OpenAIRE

    Tans-Kersten, Julie; Guan, Yanfen; Allen, Caitilyn

    1998-01-01

    Ralstonia (Pseudomonas) solanacearum causes bacterial wilt, a serious disease of many crop plants. The pathogen produces several extracellular plant cell wall-degrading enzymes, including polygalacturonases (PGs) and pectin methylesterase (Pme). Pme removes methyl groups from pectin, thereby facilitating subsequent breakdown of this cell wall component by PGs, which are known bacterial wilt virulence factors. R. solanacearum PGs could not degrade 93% methylated pectin unless the substrate was...

  4. Virulence genes and genetic diversity of Streptococcus suis serotype 2 isolates from Thailand.

    Science.gov (United States)

    Maneerat, K; Yongkiettrakul, S; Kramomtong, I; Tongtawe, P; Tapchaisri, P; Luangsuk, P; Chaicumpa, W; Gottschalk, M; Srimanote, P

    2013-11-01

    Isolates of Streptococcus suis from different Western countries as well as those from China and Vietnam have been previously well characterized. So far, the genetic characteristics and relationship between S. suis strains isolated from both humans and pigs in Thailand are unknown. In this study, a total of 245 S. suis isolates were collected from both human cases (epidemic and sporadic) and pigs (diseased and asymptomatic) in Thailand. Bacterial strains were identified by biochemical tests and PCR targeting both, the 16S rRNA and gdh genes. Thirty-six isolates were identified as serotype 2 based on serotyping and the cps2-PCR. These isolates were tested for the presence of six virulence-associated genes: an arginine deiminase (arcA), a 38-kDa protein and protective antigen (bay046), an extracellular factor (epf), an hyaluronidase (hyl), a muramidase-released protein (mrp) and a suilysin (sly). In addition, the genetic diversities of these isolates were studied by RAPD PCR and multilocus sequence typing (MLST) analysis. Four virulence-associated gene patterns (VAGP 1 to 4) were obtained, and the majority of isolates (32/36) carried all genes tested (VAGP1). Each of the three OPB primers used provided 4 patterns designated RAPD-A to RAPD-D. Furthermore, MLST analysis could also distinguish the 36 isolates into four sequence types (STs): ST1 (n = 32), ST104 (n = 2), ST233 (n = 1) and a newly identified ST, ST336 (n = 1). Dendrogram constructions based on RAPD patterns indicated that S. suis serotype 2 isolates from Thailand could be divided into four groups and that the characteristics of the individual groups were in complete agreement with the virulence gene profiles and STs. The majority (32/36) of isolates recovered from diseased pigs, slaughterhouse pigs or human patients could be classified into a single group (VAGP1, RAPD-A and ST1). This genetic information strongly suggests the transmission of S. suis isolates from pigs to humans in Thailand. Our findings are

  5. Horizontal gene transfer and bacterial diversity

    Indian Academy of Sciences (India)

    Chitra Dutta; Archana Pan

    2002-02-01

    Bacterial genomes are extremely dynamic and mosaic in nature. A substantial amount of genetic information is inserted into or deleted from such genomes through the process of horizontal transfer. Through the introduction of novel physiological traits from distantly related organisms, horizontal gene transfer often causes drastic changes in the ecological and pathogenic character of bacterial species and thereby promotes microbial diversification and speciation. This review discusses how the recent influx of complete chromosomal sequences of various microorganisms has allowed for a quantitative assessment of the scope, rate and impact of horizontally transmitted information on microbial evolution.

  6. Detection of virulence genes of Clostridium difficile by multiplex PCR.

    Science.gov (United States)

    Antikainen, Jenni; Pasanen, Tanja; Mero, Sointu; Tarkka, Eveliina; Kirveskari, Juha; Kotila, Saara; Mentula, Silja; Könönen, Eija; Virolainen-Julkunen, Anni-Riitta; Vaara, Martti; Tissari, Päivi

    2009-08-01

    Clostridium difficile strains belonging to the PCR ribotype 027, pulse-field gel electrophoresis (PFGE) type NAP1, toxinotype III and restriction endonuclease analysis group BI harbouring mutations in the tcdC gene and possessing binary toxin components A and B have been described to cause epidemics with increased morbidity and mortality. In the present study we developed a conventional multiplex PCR designed to detect selected virulence associated markers of the hypervirulent C. difficile PCR ribotype 027. The multiplex PCR assay detected the major toxins A and B, binary toxin components A and B as well as a possible deletion in the tcdC gene: a characteristic pattern of amplification products for the PCR ribotype 027 strains was detected. This rather simple method was specific for the screening of this hypervirulent C. difficile strain. The correlation between the multiplex PCR and PCR ribotyping methods was excellent. The sensitivity and specificity were 100% in our epidemiological situation. In conclusion, this multiplex PCR was found useful in the preliminary screening for the hypervirulent C. difficile PCR ribotype 027. PMID:19664132

  7. Virulence of Aeromonas hydrophila to channel catfish Ictalurus punctatus fingerlings in the presence and absence of bacterial extracellular products

    Science.gov (United States)

    Virulence of three 2009 West Alabama isolates (AL09-71, AL09-72, and AL09-73) of Aeromonas hydrophila in the presence or absence of extracellular products (ECP) from overnight bacterial culture to channel catfish fingerlings (4.6 +/- 1.3g) was investigated by both bath immersion and intraperitoneal ...

  8. Non-thermal Plasma Exposure Rapidly Attenuates Bacterial AHL-Dependent Quorum Sensing and Virulence.

    Science.gov (United States)

    Flynn, Padrig B; Busetti, Alessandro; Wielogorska, Ewa; Chevallier, Olivier P; Elliott, Christopher T; Laverty, Garry; Gorman, Sean P; Graham, William G; Gilmore, Brendan F

    2016-01-01

    The antimicrobial activity of atmospheric pressure non-thermal plasma has been exhaustively characterised, however elucidation of the interactions between biomolecules produced and utilised by bacteria and short plasma exposures are required for optimisation and clinical translation of cold plasma technology. This study characterizes the effects of non-thermal plasma exposure on acyl homoserine lactone (AHL)-dependent quorum sensing (QS). Plasma exposure of AHLs reduced the ability of such molecules to elicit a QS response in bacterial reporter strains in a dose-dependent manner. Short exposures (30-60 s) produce of a series of secondary compounds capable of eliciting a QS response, followed by the complete loss of AHL-dependent signalling following longer exposures. UPLC-MS analysis confirmed the time-dependent degradation of AHL molecules and their conversion into a series of by-products. FT-IR analysis of plasma-exposed AHLs highlighted the appearance of an OH group. In vivo assessment of the exposure of AHLs to plasma was examined using a standard in vivo model. Lettuce leaves injected with the rhlI/lasI mutant PAO-MW1 alongside plasma treated N-butyryl-homoserine lactone and n-(3-oxo-dodecanoyl)-homoserine lactone, exhibited marked attenuation of virulence. This study highlights the capacity of atmospheric pressure non-thermal plasma to modify and degrade AHL autoinducers thereby attenuating QS-dependent virulence in P. aeruginosa. PMID:27242335

  9. mADP-RTs: Versatile virulence factors from bacterial pathogens of plants and mammals

    Directory of Open Access Journals (Sweden)

    Lennart eWirthmueller

    2012-06-01

    Full Text Available Mono ADP-ribosyltransferases (mADP-RTs are a family of enzymes that cleave NAD+ and covalently attach the ADP-ribosyl moiety to target proteins. mADP-RTs are well established as important virulence factors of bacteria that infect mammals. Cholera toxin, pertussis toxin and diphteria toxin are three of the best-known examples of mADP-RTs. They modify host target proteins in order to promote infection and/or killing of the host cell. Despite low sequence similarity at the primary amino acid level, mADP-RTs share a conserved core catalytic fold and structural biology has made important contributions to elucidating how mADP-RTs modify mammalian host targets. Recently, mADP-RTs were shown to be present in plant pathogenic bacteria, suggesting that mADP-RTs are also important virulence factors of plant pathogens. Crystal structures of plant pathogenic bacterial mADP-RTs are also now available. Here we review the structure/function of mADP-RTs from pathogens of mammals and plants, highlighting both commonalities and differences.

  10. A Common Structural Motif in the Binding of Virulence Factors to Bacterial Secretion Chaperones

    International Nuclear Information System (INIS)

    Salmonella invasion protein A (SipA) is translocated into host cells by a type III secretion system (T3SS) and comprises two regions: one domain binds its cognate type III secretion chaperone, InvB, in the bacterium to facilitate translocation, while a second domain functions in the host cell, contributing to bacterial uptake by polymerizing actin. We present here the crystal structures of the SipA chaperone binding domain (CBD) alone and in complex with InvB. The SipA CBD is found to consist of a nonglobular polypeptide as well as a large globular domain, both of which are necessary for binding to InvB. We also identify a structural motif that may direct virulence factors to their cognate chaperones in a diverse range of pathogenic bacteria. Disruption of this structural motif leads to a destabilization of several chaperone-substrate complexes from different species, as well as an impairment of secretion in Salmonella

  11. The thiG Gene Is Required for Full Virulence of Xanthomonas oryzae pv. oryzae by Preventing Cell Aggregation.

    Directory of Open Access Journals (Sweden)

    Xiaoyue Yu

    Full Text Available Bacterial blight of rice is an important serious bacterial diseases of rice in many rice-growing regions, caused by Xanthomonas oryzae pv. oryzae (Xoo. The thiG gene from Xoo strain ZJ173, which is involved with thiazole moiety production in the thiamine biosynthesis pathway, is highly conserved among the members of Xanthomonas. The thiG deletion mutant displayed impaired virulence and growth in thiamine-free medium but maintained its normal growth rate in the rice tissues, indicating that the thiG gene is involved in Xoo virulence. Compared to the wild type strain, the formation of cell-cell aggregates was affected in thiG deletion mutants. Although biofilm formation was promoted, motility and migration in rice leaves were repressed in the thiG mutants, and therefore limited the expansion of pathogen infection in rice. Quorum sensing and extracellular substance are two key factors that contribute to the formation of cell-cell aggregates. Our study found that in the thiG mutant the expression of two genes, rpfC and rpfG, which form a two-component regulatory signal system involved in the regulation of biofilm formation by a second messenger cyclic di-GMP is down-regulated. In addition, our study showed that xanthan production was not affected but the expression of some genes associated with xanthan biosynthesis, like gumD, gumE, gumH and gumM, were up-regulated in thiG mutants. Taken together, these findings are the first to demonstrate the role of the thiazole biosynthsis gene, thiG, in virulence and the formation of aggregates in Xanthomonas oryzae pv. oryzae.

  12. Structural and Molecular Mechanism of CdpR Involved in Quorum-Sensing and Bacterial Virulence in Pseudomonas aeruginosa.

    Directory of Open Access Journals (Sweden)

    Jingru Zhao

    2016-04-01

    Full Text Available Although quorum-sensing (QS systems are important regulators of virulence gene expression in the opportunistic human pathogen Pseudomonas aeruginosa, their detailed regulatory mechanisms have not been fully characterized. Here, we show that deletion of PA2588 resulted in increased production of pyocyanin and biofilm, as well as enhanced pathogenicity in a mouse model. To gain insights into the function of PA2588, we performed a ChIP-seq assay and identified 28 targets of PA2588, including the intergenic region between PA2588 and pqsH, which encodes the key synthase of Pseudomonas quinolone signal (PQS. Though the C-terminal domain was similar to DNA-binding regions of other AraC family members, structural studies revealed that PA2588 has a novel fold at the N-terminal region (NTR, and its C-terminal HTH (helix-turn-helix domain is also unique in DNA recognition. We also demonstrated that the adaptor protein ClpS, an essential regulator of ATP-dependent protease ClpAP, directly interacted with PA2588 before delivering CdpR to ClpAP for degradation. We named PA2588 as CdpR (ClpAP-degradation and pathogenicity Regulator. Moreover, deletion of clpP or clpS/clpA promotes bacterial survival in a mouse model of acute pneumonia infection. Taken together, this study uncovered that CdpR is an important QS regulator, which can interact with the ClpAS-P system to regulate the expression of virulence factors and pathogenicity.

  13. DNA supercoiling and bacterial gene expression.

    Science.gov (United States)

    Dorman, Charles J

    2006-01-01

    DNA in bacterial cells is maintained in a negatively supercoiled state. This contributes to the organization of the bacterial nucleoid and also influences the global gene expression pattern in the cell through modulatory effects on transcription. Supercoiling arises as a result of changes to the linking number of the relaxed double-stranded DNA molecule and is set and reset by the action of DNA topoisomerases. This process is subject to a multitude of influences that are usually summarized as environmental stress. Responsiveness of linking number change to stress offers the promise of a mechanism for the wholesale adjustment of the transcription programme of the cell as the bacterium experiences different environments. Recent data from DNA microarray experiments support this proposition. The emerging picture is one of DNA supercoiling acting at or near the apex of a regulatory hierarchy where it collaborates with nucleoid-associated proteins and transcription factors to determine the gene expression profile of the cell. PMID:17338437

  14. Using an in-vitro biofilm model to assess the virulence potential of Bacterial Vaginosis or non-Bacterial Vaginosis Gardnerella vaginalis isolates

    OpenAIRE

    Castro, Joana; Alves, Patrícia; Sousa, Cármen Sofia Vieira; Cereija, Tatiana; França, Ângela Maria Oliveira de Sousa; Jefferson, Kimberly K; Cerca, Nuno

    2015-01-01

    Gardnerella vaginalis is the most common species found in bacterial vaginosis (BV). However, it is also present in a significant proportion of healthy women and G. vaginalis vaginal colonization does not always lead to BV. In an effort to better understand the differences between G. vaginalis isolated from women with a positive (BV) versus a negative (non-BV) diagnosis of BV, we compared the virulence potential of 7 BV and 7 non-BV G. vaginalis isolates and assessed the virulence factors rela...

  15. The Salmonella typhimurium virulence plasmid encodes a positive regulator of a plasmid-encoded virulence gene.

    OpenAIRE

    Caldwell, A L; Gulig, P A

    1991-01-01

    The 90-kb virulence plasmid of Salmonella typhimurium is necessary for invasion beyond the Peyer's patches to the mesenteric lymph nodes and spleens of orally inoculated mice. Two Tn5 insertions located on the left side of a previously identified 14-kb virulence region (P. A. Gulig and R. Curtiss III, Infect. Immun. 58:3262-3271, 1988) and mapping 272 bp from each other exhibited opposite effects on splenic infection of mice after oral inoculation. spvR23::Tn5 decreased splenic infection by 1...

  16. DNA Microarray and Gene Ontology Enrichment Analysis Reveals That a Mutation in opsX Affects Virulence and Chemotaxis in Xanthomonas oryzae pv. oryzae

    Science.gov (United States)

    Kim, Hong-Il; Park, Young-Jin

    2016-01-01

    Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial leaf blight (BLB) in rice (Oryza sativa L.). In this study, we investigated the effect of a mutation in opsX (XOO1056), which encodes a saccharide biosynthesis regulatory protein, on the virulence and bacterial chemotaxis of Xoo. We performed DNA microarray analysis, which showed that 63 of 2,678 genes, including genes related to bacterial motility (flagellar and chemotaxis proteins) were significantly downregulated (<−2 log2 fold changes) by the mutation in opsX. Indeed, motility assays showed that the mutant strain was nonmotile on semisolid agar swarm plates. In addition, a mutant strain (opsX::Tn5) showed decreased virulence against the susceptible rice cultivar, IR24. Quantitative real-time RT-PCR reaction was performed to confirm the expression levels of these genes, including those related to flagella and chemotaxis, in the opsX mutant. Our findings revealed that mutation of opsX affects both virulence and bacterial motility. These results will help to improve our understanding of Xoo and provide insight into Xoo-rice interactions. PMID:27298594

  17. Mutation of the Erwinia amylovora argD gene causes arginine auxotrophy, nonpathogenicity in apples, and reduced virulence in pears.

    Science.gov (United States)

    Ramos, Laura S; Lehman, Brian L; Peter, Kari A; McNellis, Timothy W

    2014-11-01

    Fire blight is caused by Erwinia amylovora and is the most destructive bacterial disease of apples and pears worldwide. In this study, we found that E. amylovora argD(1000)::Tn5, an argD Tn5 transposon mutant that has the Tn5 transposon inserted after nucleotide 999 in the argD gene-coding region, was an arginine auxotroph that did not cause fire blight in apple and had reduced virulence in immature pear fruits. The E. amylovora argD gene encodes a predicted N-acetylornithine aminotransferase enzyme, which is involved in the production of the amino acid arginine. A plasmid-borne copy of the wild-type argD gene complemented both the nonpathogenic and the arginine auxotrophic phenotypes of the argD(1000)::Tn5 mutant. However, even when mixed with virulent E. amylovora cells and inoculated onto immature apple fruit, the argD(1000)::Tn5 mutant still failed to grow, while the virulent strain grew and caused disease. Furthermore, the pCR2.1-argD complementation plasmid was stably maintained in the argD(1000)::Tn5 mutant growing in host tissues without any antibiotic selection. Therefore, the pCR2.1-argD complementation plasmid could be useful for the expression of genes, markers, and reporters in E. amylovora growing in planta, without concern about losing the plasmid over time. The ArgD protein cannot be considered an E. amylovora virulence factor because the argD(1000)::Tn5 mutant was auxotrophic and had a primary metabolism defect. Nevertheless, these results are informative about the parasitic nature of the fire blight disease interaction, since they indicate that E. amylovora cannot obtain sufficient arginine from apple and pear fruit tissues or from apple vegetative tissues, either at the beginning of the infection process or after the infection has progressed to an advanced state. PMID:25172854

  18. The Salmonella virulence plasmid spv genes are required for cytopathology in human monocyte-derived macrophages.

    Science.gov (United States)

    Libby, S J; Lesnick, M; Hasegawa, P; Weidenhammer, E; Guiney, D G

    2000-02-01

    The pathogenesis of serious systemic Salmonella infections is characterized by survival and proliferation of bacteria inside macrophages. Infection of human monocyte-derived macrophages in vitro with S. typhimurium or S. dublin produces cytopathology characterized by detachment of cells that contain large numbers of proliferating bacteria. This cytopathology is dependent on the expression of the bacterial spv genes, a virulence locus previously shown to markedly enhance the ability of Salmonella to produce systemic disease. After 24 h of infection, macrophage cultures contain two populations of bacteria: (i) proliferating organisms present in a detached cell fraction; and (ii) a static bacterial population in macrophages remaining attached to the culture well. Mutations in either the essential transcriptional activator SpvR or the key SpvB protein markedly reduce the cytopathic effect of Salmonella infection. The spv-dependent cytopathology in macrophages exhibits characteristics of apoptosis, with release of nucleosomes into the cytoplasm, nuclear condensation and DNA fragmentation. The current findings suggest that the mechanism of the spv effect is through induction of increased cytopathology in host macrophages. PMID:11207562

  19. Contribution of Escherichia coli alpha-hemolysin to bacterial virulence and to intraperitoneal alterations in peritonitis.

    Science.gov (United States)

    May, A K; Gleason, T G; Sawyer, R G; Pruett, T L

    2000-01-01

    Alpha-hemolysin (Hly) is a common exotoxin produced by Escherichia coli that enhances virulence in a number of clinical infections. The addition of hemolysin production to laboratory bacterial strains is known to increase the lethality of E. coli peritonitis. However, the mechanisms involved have not been determined and the contribution of hemolysin to the alterations in the host intraperitoneal environment and the leukocyte response is not known. Utilizing a rat peritonitis model, we show that wild-type hemolytic E. coli strains have a significant competitive advantage over nonhemolytic strains within the peritoneum. To examine the specific contribution of Hly to E. coli-induced virulence and alterations within the peritoneum, a mixed peritonitis model of E. coli, Bacteroides fragilis, and sterile fecal adjuvant was used. Three transformed E. coli strains were utilized: one strongly secretes active hemolysin (WAF 270), a second secretes active hemolysin but a reduced amount (WAF 260), and the third does not produce hemolysin (WAF 108). After an equal inoculum of each of the three strains, WAF 270 produced a markedly increased lethality and an increased recovery of both E. coli and B. fragilis from the host relative to the other strains. Changes in the intraperitoneal pH, degree of erythrocyte lysis, and recruitment and viability of leukocytes within the peritoneum following the induction of peritonitis differed significantly between the strongly hemolytic and nonhemolytic strains. Induction of peritonitis with WAF 270 caused a pronounced decrease in intraperitoneal pH, lysis of most of the intraperitoneal erythrocytes, and a marked decrease in recoverable viable leukocytes compared to WAF 108. Thus, hemolysin production by E. coli within the peritoneum may alter not only the host's ability to control the hemolytic strain itself but also other organisms. PMID:10603385

  20. Beyond the chromosome: the prevalence of unique extra-chromosomal bacteriophages with integrated virulence genes in pathogenic Staphylococcus aureus.

    Directory of Open Access Journals (Sweden)

    Bryan Utter

    Full Text Available In Staphylococcus aureus, the disease impact of chromosomally integrated prophages on virulence is well described. However, the existence of extra-chromosomal prophages, both plasmidial and episomal, remains obscure. Despite the recent explosion in bacterial and bacteriophage genomic sequencing, studies have failed to specifically focus on extra-chromosomal elements. We selectively enriched and sequenced extra-chromosomal DNA from S. aureus isolates using Roche-454 technology and uncovered evidence for the widespread distribution of multiple extra-chromosomal prophages (ExPΦs throughout both antibiotic-sensitive and -resistant strains. We completely sequenced one such element comprised of a 43.8 kbp, circular ExPΦ (designated ФBU01 from a vancomycin-intermediate S. aureus (VISA strain. Assembly and annotation of ФBU01 revealed a number of putative virulence determinants encoded within a bacteriophage immune evasion cluster (IEC. Our identification of several potential ExPΦs and mobile genetic elements (MGEs also revealed numerous putative virulence factors and antibiotic resistance genes. We describe here a previously unidentified level of genetic diversity of stealth extra-chromosomal elements in S. aureus, including phages with a larger presence outside the chromosome that likely play a prominent role in pathogenesis and strain diversity driven by horizontal gene transfer (HGT.

  1. A Bacterial Pathogen Displaying Temperature-Enhanced Virulence of the Microalga Emiliania huxleyi

    Science.gov (United States)

    Mayers, Teaghan J.; Bramucci, Anna R.; Yakimovich, Kurt M.; Case, Rebecca J.

    2016-01-01

    recently been shown to have acquired resistance against EhVs at elevated temperature, bacterial pathogens with temperature-dependent virulence, such as R11, may become much more important in the ecology of E. huxleyi in a warming climate. PMID:27379036

  2. A Bacterial Pathogen Displaying Temperature-Enhanced Virulence of the Microalga Emiliania huxleyi.

    Science.gov (United States)

    Mayers, Teaghan J; Bramucci, Anna R; Yakimovich, Kurt M; Case, Rebecca J

    2016-01-01

    shown to have acquired resistance against EhVs at elevated temperature, bacterial pathogens with temperature-dependent virulence, such as R11, may become much more important in the ecology of E. huxleyi in a warming climate. PMID:27379036

  3. Complete DNA sequence and gene analysis of the virulence plasmid pCP301 of Shigella flexneri 2a

    Institute of Scientific and Technical Information of China (English)

    张继瑜; 刘红; 张笑兵; 杨剑; 杨帆; 杨国威; 沈岩; 侯云德; 金奇

    2003-01-01

    The complete nucleotide sequence and organization of the large virulence plasmid pCP301 (termed by us) of Shigella flexneri 2a strain 301 were determined and analyzed. The result showed that the entire DNA sequence of pCP301 is composed of 221618 bp which form a circular plasmid. Sequence analysis identified 272 open reading frames (ORFs), among which, 194 correspond to the proteins described previously, 61 have low identity (<60%) to known proteins and the rest 17 have no regions of significant homology with proteins in database. The genes of pCP301 mainly include the genes associated with bacterial virulence, the genes associated with regulation and the genes relating to plasmid maintenance, stability and DNA metabolism. Insertion sequence (IS) elements are 68 kb in length and account for 30 percent of complete sequence of the plasmid which indicates that gene multiple rearrangements of the pCP301 have taken place in Shigella flexneri evolution history. The research result is helpful for interpreting the pathogenesis of Shigella, as well as the genetics and evolution of the plasmid.

  4. Epigenetic control of virulence gene expression in Pseudomonas aeruginosa by a LysR-type transcription regulator.

    Directory of Open Access Journals (Sweden)

    Keith H Turner

    2009-12-01

    Full Text Available Phenotypic variation within an isogenic bacterial population is thought to ensure the survival of a subset of cells in adverse conditions. The opportunistic pathogen Pseudomonas aeruginosa variably expresses several phenotypes, including antibiotic resistance, biofilm formation, and the production of CupA fimbriae. Here we describe a previously unidentified bistable switch in P. aeruginosa. This switch controls the expression of a diverse set of genes, including aprA, which encodes the secreted virulence factor alkaline protease. We present evidence that bistable expression of PA2432, herein named bexR (bistable expression regulator, which encodes a LysR-type transcription regulator, controls this switch. In particular, using DNA microarrays, quantitative RT-PCR analysis, chromatin immunoprecipitation, and reporter gene fusions, we identify genes directly under the control of BexR and show that these genes are bistably expressed. Furthermore, we show that bexR is itself bistably expressed and positively autoregulated. Finally, using single-cell analyses of a GFP reporter fusion, we present evidence that positive autoregulation of bexR is necessary for bistable expression of the BexR regulon. Our findings suggest that a positive feedback loop involving a LysR-type transcription regulator serves as the basis for an epigenetic switch that controls virulence gene expression in P. aeruginosa.

  5. The prevalence of virulence genes of E. coli strains isolated from children with urinary tract infection

    International Nuclear Information System (INIS)

    To evaluate the prevalence of virulence genes in E. coli strains isolated from urine samples of children with urinary tract infection(UTI) and their correlation with clinical data, we isolated E. coli strains from urine samples of children with UTI during the period of August 2005 - August 2006 and studied them for the presence of the virulence genes by PCR. A total of 96 E. coli strains were isolated. The prevalence of genes, pyelonephritis associated pili (pap genes), S-family adhesions (sfa gene), hemolysin (hly gene), and cytotoxic nercotizing factor type 1 (cnf-1-1 gene) among the isolated strains was 27.1%, 14.6%, 13.5% and 22.9 %, respectively. Pyelonephritis was more prevalent in the cases with positive virulence genes. The results showed significant correlation between age of the patient and the presence of the genes (P< 0.05). Cnf-1 gene was significantly more common in samples of patients with abnormal finding on the ultrasound of kidneys (P0.049). Our study demonstrated higher prevalence of pyelonephritis in the presence of E. coli virulence genes. Detection of the genes in urine samples may help in the management of UTI. (author)

  6. The prevalence of virulence genes of E. coli strains isolated from children with urinary tract infection

    Directory of Open Access Journals (Sweden)

    Farshad Shohreh

    2009-01-01

    Full Text Available To evaluate the prevalence of virulence genes in E. coli strains isolated from urine samples of children with urinary tract infection(UTI and their correlation with clinical data, we iso-lated E. coli strains from urine samples of children with UTI during the period of August 2005 - August 2006 and studied them for the presence of the virulence genes by PCR. A total of 96 E. coli strains were isolated. The prevalence of genes, pyelonephritis associated pili (pap genes, S-family adhesions (sfa gene, hemolysin (hly gene, and cytotoxic nercotizing factor type 1 (cnf-1-1 gene among the isolated strains was 27.1%, 14.6%, 13.5% and 22.9 %, respectively. Pyelonephritis was more prevalent in the cases with positive virulence genes. The results showed significant correlation bet-ween age of the patient and the presence of the genes (P< 0.05. Cnf-1 gene was significantly more common in samples of patients with abnormal finding on the ultrasound of kidneys (P= 0.049. Our study demonstrated higher prevalence of pyelonephritis in the presence of E. coli virulence genes. Detection of the genes in urine samples may help in the management of UTI.

  7. Development and evaluation of multiplex PCR assays for rapid detection of virulence-associated genes in Arcobacter species.

    Science.gov (United States)

    Whiteduck-Léveillée, Jenni; Cloutier, Michel; Topp, Edward; Lapen, David R; Talbot, Guylaine; Villemur, Richard; Khan, Izhar U H

    2016-02-01

    As the pathogenicity of Arcobacter species might be associated with various virulence factors, this study was aimed to develop and optimize three single-tube multiplex PCR (mPCR) assays that can efficiently detect multiple virulence-associated genes (VAGs) in Arcobacter spp. including the Arcobacter butzleri, Arcobacter cryaerophilus and Arcobacter skirrowii, respectively. The recognized target virulence factors used in the study were fibronectin binding protein (cj1349), filamentous hemagglutinin (hecA), hemolysin activation protein (hecB), hemolysin (tlyA), integral membrane protein virulence factor (mviN), invasin (ciaB), outer membrane protein (irgA) and phospholipase (pldA). Identical results were obtained between singleplex PCR and mPCR assays and no cross- and/or non-specific amplification products were obtained when tested against other closely related bacterial species. The sensitivities of these three mPCR assays were ranging from 1ngμL(-1) to 100ngμL(-1) DNA. The developed assays with combinations of duplex or triplex PCR primer pairs of VAGs were further evaluated and validated by applying them to isolates of the A. butzleri, A. cryaerophilus and A. skirrowii recovered from fecal samples of human and animal origins. The findings revealed that the distribution of the ciaB (90%), mviN (70%), tlyA (50%) and pldA (45%) genes among these target species was significantly higher than the hecA (16%), hecB (10%) and each of irgA and cj1349 (6%) genes, respectively. The newly developed mPCR assays can be used as rapid technique and useful markers for the detection, prevalence and profiling of VAGs in the Arcobacter spp. Moreover, these assays can easily be performed with a high throughput to give a presumptive identification of the causal pathogen in epidemiological investigation of human infections. PMID:26769558

  8. Quorum sensing in Aeromonas salmonicida subsp. achromogenes and the effect of the autoinducer synthase AsaI on bacterial virulence

    DEFF Research Database (Denmark)

    Schwenteit, Johanna; Gram, Lone; Nielsen, Kristian Fog;

    2011-01-01

    Ideficient mutant was 20-fold higher than that of the isogenic wt strain and the mean day to death of the mutant was significantly prolonged. Furthermore, the expression of two virulence factors (a toxic protease, AsaP1, and a cytotoxic factor) and a brown pigment were reduced in the mutant. AsaP1 productionwas...... an important virulence factor, AsaP1, without affecting bacterial growth, makes A. salmonicida subsp. achromogenes an interesting target organism to study the effects of QS in disease development and QSI in disease control.......The Gram-negative fish pathogenic bacterium Aeromonas salmonicida possesses the LuxIRtype quorum sensing (QS) system, termed AsaIR. In this study the role of QS in A. salmonicida subsp. achromogenes virulence and pigment production was investigated. Five wild-type Asa strains induced the N...

  9. Effects of quorum sensing autoinducer degradation gene on virulence and biofilm formation of Pseudomonas aeruginosa

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The aiiA gene from Bacillus thuringiensis was cloned into the Pseudomonas/E. coli shuttle vector and transformed into Pseudomonas aeruginosa strain PAO1. Western blotting showed that the AiiA protein was expressed in PAO1. After induction by IPTG for 6 h and 18 h, expression of the aiiA gene in PAO1 completely degraded the quorum sensing autoinducers N-acylhomoserine lactones (AHLs): N-oxododecanoyl-L-homoserine lactone (OdDHL) and N-butyryl-L-homoserine lactone (BHL). The re- duced amount of AHLs in PAO1 was also correlated with decreased expression and production of several virulence factors such as elastase and pyocyanin. AiiA expression also influenced bacterial swarming motility. Most importantly, our studies indicated that aiiA played significant roles in P. aeruginosa biofilm formation and dispersion, as observed by the differences of the biofilm formation on liquid and solid surfaces, and biofilm structures under a scanning electron microscope.

  10. Effects of quorum sensing autoinducer degradation gene on virulence and biofilm formation of Pseudomonas aeruginosa

    Institute of Scientific and Technical Information of China (English)

    WANG Yao; DAI Yue; ZHANG Yong; HU YangBo; YANG BaoYu; CHEN ShiYun

    2007-01-01

    The aiiA gene from Bacillus thuringiensis was cloned into the Pseudomonas/E. coli shuttle vector and transformed into Pseudomonas aeruginosa strain PAO1. Western blotting showed that the AiiA protein was expressed in PAO1. After induction by IPTG for 6 h and 18 h, expression of the aiiA gene in PAO1completely degraded the quorum sensing autoinducers N-acylhomoserine lactones (AHLs):N-oxododecanoyI-L-homoserine lactone (OdDHL) and N-butyryI-L-homoserine lactone (BHL). The reduced amount of AHLs in PAO1 was also correlated with decreased expression and production of several virulence factors such as elastase and pyocyanin. AiiA expression also influenced bacterial swarming motility. Most importantly, our studies indicated that aiiA played significant roles in P.aeruginosa biofilm formation and dispersion, as observed by the differences of the biofilm formation on liquid and solid surfaces, and biofilm structures under a scanning electron microscope.

  11. Identification of a third msa gene in Renibacterium salmoninarum and the associated virulence phenotype.

    Science.gov (United States)

    Rhodes, Linda D; Coady, Alison M; Deinhard, Rebecca K

    2004-11-01

    Renibacterium salmoninarum, a gram-positive diplococcobacillus, causes bacterial kidney disease, a condition that can result in extensive morbidity and mortality among stocks of fish. An immunodominant extracellular protein, called major soluble antigen (MSA), is encoded by two identical genes, msa1 and msa2. We found evidence for a third msa gene, msa3, which appears to be a duplication of msa1. Unlike msa1 and msa2, msa3 is not present in all isolates of R. salmoninarum. The presence of the msa3 locus does not affect total MSA production in culture conditions. In a challenge study, isolates possessing the msa3 locus reduced median survival in juvenile chinook salmon (Oncorhynchus tshawytscha) by an average of 34% at doses of < or =10(5) cells per fish compared to isolates lacking the msa3 locus. In contrast, no difference in survival was observed at the highest dose, 10(6) cells per fish. The phenotype associated with the msa3 locus and its nonuniform distribution may contribute to observed differences in virulence among R. salmoninarum isolates. PMID:15528510

  12. Virulence gene profiles of avian pathogenic Escherichia coli isolated from chickens with colibacillosis in Bulawayo, Zimbabwe

    Directory of Open Access Journals (Sweden)

    Joshua Mbanga

    2015-02-01

    Full Text Available Colibacillosis, a disease caused by avian pathogenic Escherichia coli (APEC, is one of the main causes of economic losses in the poultry industry worldwide. This study was carried out in order to determine the APEC-associated virulence genes contained by E. coli isolates causing colibacillosis in chickens. A total of 45 E. coli isolates were obtained from the diagnostics and research branch of the Central Veterinary Laboratories, Bulawayo, Zimbabwe. These isolates were obtained from chickens with confirmed cases of colibacillosis after postmortem examination. The presence of the iutA, hlyF, ompT, frz, sitD, fimH, kpsM, sitA, sopB, uvrY, pstB and vat genes were investigated by multiplex polymerase chain reaction (PCR assay. Of the 45 isolates, 93% were positive for the presence of at least one virulence gene. The three most prevalent virulence genes were iutA (80%, fimH (33.3% and hlyF (24.4%. The kpsM, pstB and ompT genes had the lowest prevalence, having been detected in only 2.2% of the isolates. All 12 virulence genes studied were detected in the 45 APEC isolates. Virulence gene profiles were constructed for each APEC isolate from the multiplex data. The APEC isolates were profiled as 62.2% fitting profile A, 31.1% profile B and 6.7% profile C. None of the isolates had more than seven virulence genes. Virulence profiles of Zimbabwean APEC isolates are different from those previously reported. Zimbabwean APEC isolates appear to be less pathogenic and may rely on environmental factors and stress in hosts to establish infection.

  13. Streptococcus pneumoniae arginine synthesis genes promote growth and virulence in pneumococcal meningitis

    NARCIS (Netherlands)

    J.R. Piet; M. Geldhoff; B.D.C. van Schaik; M.C. Brouwer; M. Valls Seron; M.E. Jakobs; K. Schipper; Y. Pannekoek; A.H. Zwinderman; T. van der Poll; A.H.C. van Kampen; F. Baas; A van der Ende; D. van de Beek

    2014-01-01

    Streptococcus pneumoniae (pneumococcus) is a major human pathogen causing pneumonia, sepsis and bacterial meningitis. Using a clinical phenotype based approach with bacterial whole-genome sequencing we identified pneumococcal arginine biosynthesis genes to be associated with outcome in patients with

  14. Nigribactin, a Novel Siderophore from Vibrio nigripulchritudo, Modulates Staphylococcus aureus Virulence Gene Expression

    DEFF Research Database (Denmark)

    Nielsen, Anita; Månsson, Maria; Wietz, Matthias;

    2012-01-01

    Staphylococcus aureus is a serious human pathogen that employs a number of virulence factors as part of its pathogenesis. The purpose of the present study was to explore marine bacteria as a source of compounds that modulate virulence gene expression in S. aureus. During the global marine Galathea...... that 68 out of 83 marine bacteria (affiliated with the Vibrionaceae and Pseudoalteromonas sp.) influenced expression of S. aureus hla encoding α-hemolysin toxin and/or spa encoding Protein A. The isolate that upon initial screening showed the highest degree of interference (crude ethyl acetate extract......, enterobactin, failed to influence S. aureus virulence gene expression. This study shows that marine microorganisms produce compounds with potential use in therapeutic strategies targeting virulence rather than viability of human pathogens....

  15. Mycobacterium bovis-infected macrophages from resistant and susceptible cattle exhibited a differential pro-inflammatory gene expression profile depending on strain virulence.

    Science.gov (United States)

    Alfonseca-Silva, Edgar; Hernández-Pando, Rogelio; Gutiérrez-Pabello, José A

    2016-08-01

    Mycobacterium bovis, the causative agent of bovine tuberculosis, is an intracellular bacterium that normally persists inside host macrophages. However, the influence of bacterial virulence and host resistance on the final outcome in this interaction is not well known. In this study, we infected macrophages isolated from natural disease resistant (R) and susceptible (S) cattle donors with M. bovis strains characterized as attenuated and virulent to assess pro-inflammatory cytokine (TNFα, IL-12, IL-18, IL-1β, IL-6), chemokine (MCP-1, MCP-2, MIP-1), macrophage receptor (MSR1, TLR2, TLR4, MMR) and iNOS mRNA expression levels. Our findings identified a pro-inflammatory gene expression profile as a common feature after M. bovis infection regardless of bacterial virulence, however in S macrophages a superior expression was induced by the attenuated strain, whereas in R macrophages it was accomplished by the virulent M. bovis. A macrophage pro-inflammatory profile is intended to control M. bovis intracellular growth; however the host resistant phenotype plays a determinant role in it, since R macrophages had better intracellular bacterial control than S cells. PMID:26970816

  16. Analysis of subtelomeric virulence gene families in Plasmodium falciparum by comparative transcriptional profiling

    OpenAIRE

    Witmer, Kathrin; Schmid, Christoph D.; Brancucci, Nicolas M. B.; Luah, Yen-Hoon; Preiser, Peter R.; Bozdech, Zbynek; Voss, Till S.

    2012-01-01

    Summary The Plasmodium falciparum genome is equipped with several subtelomeric gene families that are implicated in parasite virulence and immune evasion. Members of these families are uniformly positioned within heterochromatic domains and are thus subject to variegated expression. The best-studied example is that of the var family encoding the major parasite virulence factor P. falciparum erythrocyte membrane protein 1 (PfEMP1). PfEMP1 undergoes antigenic variation through switches in mutua...

  17. Expression of the Salmonella virulence plasmid gene spvB in cultured macrophages and nonphagocytic cells.

    OpenAIRE

    Fierer, J.; Eckmann, L; Fang, F.; Pfeifer, C; Finlay, B B; Guiney, D

    1993-01-01

    Certain serotypes of salmonellae carry virulence plasmids that greatly enhance the pathogenicity of these bacteria in experimentally infected mice. This phenotype is largely attributable to the 8-kb spv regulon. However, spv genes are not expressed while bacteria grow in vitro. We now show that spvB, which is required for virulence, is expressed rapidly after Salmonella dublin is ingested by cultured J774 and murine peritoneal macrophages and that expression is not affected by the alkalinizat...

  18. Altered virulence potential of Salmonella Enteritidis cultured in different foods: A cumulative effect of differential gene expression and immunomodulation.

    Science.gov (United States)

    Jaiswal, Sangeeta; Sahoo, Prakash Kumar; Ryan, Daniel; Das, Jugal Kishore; Chakraborty, Eesha; Mohakud, Nirmal Kumar; Suar, Mrutyunjay

    2016-08-01

    Salmonella enterica serovars Enteritidis (S. Enteritidis) is one of the most common causes of food borne illness. Bacterial growth environment plays an important role in regulating gene expression thereby affecting the virulence profile of the bacteria. Different foods present diverse growth conditions which may affect the pathogenic potential of the bacteria. In the present study, the effect of food environments on the pathogenic potential of S. Enteritidis has been evaluated. S. Enteritidis was grown in different foods e.g. egg white, peanut butter and milk, and virulent phenotypes were compared to those grown in Luria Bertani broth. In-vivo experiments in C57BL/6 mice revealed S. Enteritidis grown in egg white did not induce significant (ppeanut butter showed different degrees of virulence in mice as compared to those grown in LB media. Thus, the present study demonstrates that, S. Enteritidis grown in egg white colonizes systemic sites without causing colitis in a mouse model, while bacteria grown in milk and peanut butter show different pathogenicity profiles suggesting that food environments significantly affect the pathogenicity of S. Enteritidis. PMID:27132148

  19. A Bacterial Virulence Protein Promotes Pathogenicity by Inhibiting the Bacterium's Own F1Fo ATP Synthase

    OpenAIRE

    Lee, Eun-Jin; Pontes, Mauricio H.; Groisman, Eduardo A.

    2013-01-01

    Several intracellular pathogens including Salmonella enterica and Mycobacterium tuberculosis require the virulence protein MgtC to survive within macrophages and to cause a lethal infection in mice. We now report that, unlike secreted virulence factors that target the host vacuolar ATPase to withstand phagosomal acidity, the MgtC protein acts on Salmonella's own F1Fo ATP synthase. This complex couples proton translocation to ATP synthesis/ hydrolysis and is required for virulence. We establis...

  20. Bacterial pathogen gene regulation: a DNA-structure-centred view of a protein-dominated domain.

    Science.gov (United States)

    Dorman, Charles J; Colgan, Aoife; Dorman, Matthew J

    2016-07-01

    The mechanisms used by bacterial pathogens to regulate the expression of their genes, especially their virulence genes, have been the subject of intense investigation for several decades. Whole genome sequencing projects, together with more targeted studies, have identified hundreds of DNA-binding proteins that contribute to the patterns of gene expression observed during infection as well as providing important insights into the nature of the gene products whose expression is being controlled by these proteins. Themes that have emerged include the importance of horizontal gene transfer to the evolution of pathogens, the need to impose regulatory discipline upon these imported genes and the important roles played by factors normally associated with the organization of genome architecture as regulatory principles in the control of virulence gene expression. Among these architectural elements is the structure of DNA itself, its variable nature at a topological rather than just at a base-sequence level and its ability to play an active (as well as a passive) part in the gene regulation process. PMID:27252403

  1. Frequencies of virulence genes and pulse field gel electrophoresis fingerprints in Escherichia coli isolates from canine pyometra.

    Science.gov (United States)

    Maluta, Renato P; Borges, Clarissa A; Beraldo, Lívia G; Cardozo, Marita V; Voorwald, Fabiana A; Santana, André M; Rigobelo, Everlon C; Toniollo, Gilson H; Avila, Fernando A

    2014-11-01

    Escherichia coli is the most common bacterial agent isolated from canine pyometra. The frequencies of 24 virulence genes and pulsed field gel electrophoresis (PFGE) profiles were determined for 23 E. coli isolates from cases of canine pyometra in Brazil. The frequencies of virulence genes were 91.3% fimH, 91.3% irp-2, 82.6% fyuA, 56.5% iroN, 47.8% traT, 39.1% usp, 34.8% sfaD/E, 34.8% tsh, 30.4% papC, 30.4% hlyA, 26.1% papGIII, 26.1% cnf-1, 21.7% papE/F, 21.7% iss, 17.4% iutA, 17.4% ompT, 17.4% cvaC, 17.4% hlyF, 17.4% iucD, 13.0% iucC, 13.0% astA, 4.3% papGII, 0% afaB/C and 0% papGI. The high frequency of yersiniabactin (fyuA and irp2) and salmochelin (iroN) genes suggests that iron uptake systems might be important in the pathogenesis of canine pyometra. PFGE profiles of 19 isolates were heterogeneous, confirming that E. coli isolates from canine pyometra are unlikely to be epidemic clones. PMID:25201253

  2. Molecular identification and detection of virulence genes among Pseudomonas aeruginosa isolated from different infectious origins

    Directory of Open Access Journals (Sweden)

    Vajiheh Sadat Nikbin

    2012-09-01

    Full Text Available Background and Objectives: Pseudomonas aeruginosa possesses a variety of virulence factors that may contribute to its pathogenicity. The aim of this study was to rapid identification of clinical P. aeruginosa based on PCR amplification oprI and oprL. In order to find out any relation between special virulence factors and special manifestation of P. aeruginosa infections we detected virulence factors among these isolates by PCR. Ribotyping was used to evaluate the clonal relationship between strains with the same genetic patterns of the genes studied.Material and Methods: In this study, 268 isolates of P. aeruginosa were recovered from burn, wound and pulmonary tract infections. PCR of oprI, oprL, toxA, lasB, exoS and nan1 genes was performed. One hundred and four isolates were selected randomly to investigate clonal diversity of the isolates using ribotyping using SmaI.Results and Conclusions: All P. aeruginosa isolates in this study carried oprI, oprL and lasB genes. Difference between exoS prevalence in isolates from pulmonary tract and burn or wound isolates was statistically significant (P<0.05. Prevalence of nan1 and toxA gene was significantly higher in burn and pulmonary tract isolates, respectively. Ribotyping showed that Most of the isolates (87% belonged to clone A and B.PCR of oprI, oprL and toxA genes is recommended for molecular identification of P. aeruginosa. Determination of different virulence genes of P. aeruginosa isolates suggests that they are associated with different levels of intrinsic virulence and pathogenicity. Ribotyping showed that strains with similar virulence genes don’t necessarily have similar ribotype patterns.

  3. 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.

  4. Differences in extended-spectrum beta-lactamase producing Escherichia coli virulence factor genes in the Baltic Sea region.

    Science.gov (United States)

    Lillo, Jana; Pai, Kristiine; Balode, Arta; Makarova, Mariia; Huik, Kristi; Kõljalg, Siiri; Ivanova, Marina; Kaftyreva, Lidia; Miciuleviciene, Jolanta; Naaber, Paul; Parv, Kristel; Pavelkovich, Anastasia; Rööp, Tiiu; Toompere, Karolin; Suzhaeva, Ludmila; Sepp, Epp

    2014-01-01

    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. PMID:25250320

  5. Differences in Extended-Spectrum Beta-Lactamase Producing Escherichia coli Virulence Factor Genes in the Baltic Sea Region

    Science.gov (United States)

    Balode, Arta; Makarova, Mariia; Huik, Kristi; Kõljalg, Siiri; Kaftyreva, Lidia; Miciuleviciene, Jolanta; Naaber, Paul; Rööp, Tiiu; Toompere, Karolin; Suzhaeva, Ludmila; Sepp, Epp

    2014-01-01

    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. PMID:25250320

  6. Culturable bacterial microbiota of Plagiodera versicolora (L.) (Coleoptera: Chrysomelidae) and virulence of the isolated strains.

    Science.gov (United States)

    Demirci, Meryem; Sevim, Elif; Demir, İsmail; Sevim, Ali

    2013-05-01

    Plagiodera versicolora (Laicharting, 1781) (Coleoptera: Chrysomelidae) is an important forest pest which damages many trees such as willow, poplar, and hazelnut. In order to find new microbes that can be utilized as a possible microbial control agent against this pest, we investigated the culturable bacterial flora of it and tested the isolated bacteria against P. versicolora larvae and adults. We were able to isolate nine bacteria from larvae and adults. The isolates were characterized using a combination of morphological, biochemical, and physiological methods. Additionally, we sequenced the partial sequence of the 16S rRNA gene to verify conventional identification results. Based on characterization studies, the isolates were identified as Staphylococcus sp. Pv1, Rahnella sp. Pv2, Rahnella sp. Pv3, Rahnella sp. Pv4, Rahnella sp. Pv5, Pantoea agglomerans Pv6, Staphylococcus sp. Pv7, Micrococcus luteus Pv8, and Rahnella sp. Pv9. The highest insecticidal activity against larvae and adults was obtained from M. luteus Pv8 with 50 and 40 % mortalities within 10 days after treatment, respectively. Extracellular enzyme activity of the bacterial isolates such as amylase, proteinase, lipase, cellulose, and chitinase was also determined. Consequently, our results show that M. luteus Pv8 might be a good candidate as a possible microbial control agent against P. versicolora and were discussed with respect to biocontrol potential of the bacterial isolates. PMID:23054688

  7. Phase variation leads to the misidentification of a Neisseria gonorrhoeae virulence gene.

    Directory of Open Access Journals (Sweden)

    Mark T Anderson

    Full Text Available Neisseria gonorrhoeae is the causative agent of gonorrhea and an obligate pathogen of humans. The Opa proteins of these bacteria are known to mediate attachment and internalization by host cells, including neutrophils. The Opa protein repertoire of a typical N. gonorrhoeae isolate is encoded on ~11 genes distributed throughout the chromosome and is subject to stochastic changes in expression through phase variation. Together, these characteristics make Opa proteins a critical yet unpredictable aspect of any experimental investigation into the interaction of N. gonorrhoeae with host cells. The goal of this study was to identify novel virulence factors of N. gonorrhoeae by assessing the contribution of a set of uncharacterized hydrogen peroxide-induced genes to bacterial survival against neutrophil-mediated killing. To this end, a strain harboring an engineered mutation in the NGO0322 gene was identified that exhibited increased sensitivity to neutrophil-mediated killing, enhanced internalization by neutrophils, and the ability to induce high levels of neutrophil-generated reactive oxygen species. Each of these phenotypes reverted to near wild-type levels following genetic complementation of the NGO0322 mutation. However, after immunoblot analysis of Opa proteins expressed by the isogenic parent, mutant, and genetically complemented strains, it was determined that phase variation had resulted in a disparity between the Opa profiles of these strains. To determine whether Opa phase variation, rather than NGO0322 mutation, was the cause of the observed neutrophil-related phenotypes, NGO0322 function was investigated in N. gonorrhoeae strains lacking all Opa proteins or constitutively expressing the OpaD variant. In both cases, mutation of NGO0322 did not alter survival of gonococci in the presence of neutrophils. These results demonstrate the importance of controlling for the frequent and random variation in Opa protein production by N. gonorrhoeae

  8. Virulence of Klebsiella pneumoniae isolates harboring bla KPC-2 carbapenemase gene in a Caenorhabditis elegans model.

    Directory of Open Access Journals (Sweden)

    Jean-Philippe Lavigne

    Full Text Available Klebsiella pneumoniae carbapenemase (KPC is a carbapenemase increasingly reported worldwide in Enterobacteriaceae. The aim of this study was to analyze the virulence of several KPC-2-producing K. pneumoniae isolates. The studied strains were (i five KPC-2 clinical strains from different geographical origins, belonging to different ST-types and possessing plasmids of different incompatibility groups; (ii seven transformants obtained after electroporation of either these natural KPC plasmids or a recombinant plasmid harboring only the bla KPC-2 gene into reference strains K. pneumoniae ATCC10031/CIP53153; and (iii five clinical strains cured of plasmids. The virulence of K. pneumoniae isolates was evaluated in the Caenorhabditis elegans model. The clinical KPC producers and transformants were significantly less virulent (LT50: 5.5 days than K. pneumoniae reference strain (LT50: 4.3 days (p<0.01. However, the worldwide spread KPC-2 positive K. pneumoniae ST258 strains and reference strains containing plasmids extracted from K. pneumoniae ST258 strains had a higher virulence than KPC-2 strains belonging to other ST types (LT50: 5 days vs. 6 days, p<0.01. The increased virulence observed in cured strains confirmed this trend. The bla KPC-2 gene itself was not associated to increased virulence.

  9. DETECTION OF VIRULENCE GENES IN ENVIRONMENTAL STRAINS OF Vibrio cholerae FROM ESTUARIES IN NORTHEASTERN BRAZIL

    Directory of Open Access Journals (Sweden)

    Francisca Gleire Rodrigues de Menezes

    2014-09-01

    Full Text Available The objectives of this study were to detect the presence of Vibrio cholerae in tropical estuaries (Northeastern Brazil and to search for virulence factors in the environmental isolates. Water and sediment samples were inoculated onto a vibrio-selective medium (TCBS, and colonies with morphological resemblance to V. cholerae were isolated. The cultures were identified phenotypically using a dichotomous key based on biochemical characteristics. The total DNA extracted was amplified by PCR to detect ompW and by multiplex PCR to detect the virulence genes ctx, tcp, zot and rfbO1. The results of the phenotypic and genotypic identification were compared. Nine strains of V. cholerae were identified phenotypically, five of which were confirmed by detection of the species-specific gene ompW. The dichotomous key was efficient at differentiating environmental strains of V. cholerae. Strains of V. cholerae were found in all four estuaries, but none possessed virulence genes.

  10. Expression of bacterial virulence factors and cytokines during in vitro macrophage infection by enteroinvasive Escherichia coli and Shigella flexneri: a comparative study

    Directory of Open Access Journals (Sweden)

    Silvia Y Bando

    2010-09-01

    Full Text Available Enteroinvasive Escherichia coli (EIEC and Shigellaspp cause bacillary dysentery in humans by invading and multiplying within epithelial cells of the colonic mucosa. Although EIEC and Shigellashare many genetic and biochemical similarities, the illness caused by Shigellais more severe. Thus, genomic and structure-function molecular studies on the biological interactions of these invasive enterobacteria with eukaryotic cells have focused on Shigella rather than EIEC. Here we comparatively studied the interactions of EIEC and of Shigella flexneriwith cultured J774 macrophage-like cells. We evaluated several phenotypes: (i bacterial escape from macrophages after phagocytosis, (ii macrophage death induced by EIEC and S. flexneri, (iii macrophage cytokine expression in response to infection and (iv expression of plasmidial (pINV virulence genes. The results showed thatS. flexneri caused macrophage killing earlier and more intensely than EIEC. Both pathogens induced significant macrophage production of TNF, IL-1 and IL-10 after 7 h of infection. Transcription levels of the gene invasion plasmid antigen-C were lower in EIEC than in S. flexneri throughout the course of the infection; this could explain the diminished virulence of EIEC compared to S. flexneri.

  11. Expression of bacterial virulence factors and cytokines during in vitro macrophage infection by enteroinvasive Escherichia coli and Shigella flexneri: a comparative study.

    Science.gov (United States)

    Bando, Silvia Y; Moreno, Ana C R; Albuquerque, José A T; Amhaz, Juliana M K; Moreira-Filho, Carlos A; Martinez, Marina B

    2010-09-01

    Enteroinvasive Escherichia coli (EIEC) and Shigella spp cause bacillary dysentery in humans by invading and multiplying within epithelial cells of the colonic mucosa. Although EIEC and Shigella share many genetic and biochemical similarities, the illness caused by Shigella is more severe. Thus, genomic and structure-function molecular studies on the biological interactions of these invasive enterobacteria with eukaryotic cells have focused on Shigella rather than EIEC. Here we comparatively studied the interactions of EIEC and of Shigella flexneri with cultured J774 macrophage-like cells. We evaluated several phenotypes: (i) bacterial escape from macrophages after phagocytosis, (ii) macrophage death induced by EIEC and S. flexneri, (iii) macrophage cytokine expression in response to infection and (iv) expression of plasmidial (pINV) virulence genes. The results showed that S. flexneri caused macrophage killing earlier and more intensely than EIEC. Both pathogens induced significant macrophage production of TNF, IL-1 and IL-10 after 7 h of infection. Transcription levels of the gene invasion plasmid antigen-C were lower in EIEC than in S. flexneri throughout the course of the infection; this could explain the diminished virulence of EIEC compared to S. flexneri. PMID:20944993

  12. The constancy of gene conservation across divergent bacterial orders

    Directory of Open Access Journals (Sweden)

    Ackermann Martin

    2009-01-01

    Full Text Available Abstract Background Orthologous genes are frequently presumed to perform similar functions. However, outside of model organisms, this is rarely tested. One means of inferring changes in function is if there are changes in the level of gene conservation and selective constraint. Here we compare levels of gene conservation across three bacterial groups to test for changes in gene functionality. Findings The level of gene conservation for different orthologous genes is highly correlated across clades, even for highly divergent groups of bacteria. These correlations do not arise from broad differences in gene functionality (e.g. informational genes vs. metabolic genes, but instead seem to result from very specific differences in gene function. Furthermore, these functional differences appear to be maintained over very long periods of time. Conclusion These results suggest that even over broad time scales, most bacterial genes are under a nearly constant level of purifying selection, and that bacterial evolution is thus dominated by selective and functional stasis.

  13. A study of bacterial gene regulatory mechanisms

    DEFF Research Database (Denmark)

    Hansen, Sabine

    GRNs this thesis also provided the first evidence of the sensor histidine kinase VC1831 being an additional player in the Vibrio cholerae quorum sensing (QS) GRN. Bacteria use a process of cell-cell communication called QS which enable the bacterial cells to collectively control their gene expression...... using small signaling molecules called autoinducers, thereby coordinating group behavior. At the heart of the V. cholerae QS response lie four small RNA (sRNA) molecules called the quorum regulatory RNAs (Qrr). This PhD thesis provides evidence that the sensor histidine kinase VC1831 is regulated by the...... Qrr sRNAs. It is further shown that VC1831 feeds back to activate the expression the Qrrs, presumably via phosphorylation of LuxU. Thus, VC1831, which responds to an unknown ligand, is a new player in the V. cholerae QS response. Prior to this report, the two autoinducer sensors CqsS and LuxQ were the...

  14. 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.

    Science.gov (United States)

    Puah, Suat Moi; Chua, Kek Heng; Tan, Jin Ai Mary Anne

    2016-02-01

    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. PMID:26861367

  15. 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.

  16. Virulence-associated genes in avian pathogenic Escherichia coli from laying hens in Apulia, Southern Italy.

    Science.gov (United States)

    Circella, E; Pennelli, D; Tagliabue, S; Camarda, A

    2012-01-01

    1. Escherichia coli isolated from lesions (Avian Pathogenic E. coli - APEC) of layer hens affected by colibacillosis and from intestinal contents of clinically-healthy birds (Avian Faecal E. coli - AFEC) were serotyped. All the isolates were investigated for the presence of virulence genes to determine which genes were more closely related to those from lesions. 2. A number of different serogroups were detected, O78 being predominant among the isolates from colibacillosis. 3. E. coli isolated from lesions were not linked to a specific pathotype (set of common virulence genes). 4. The presence of the virulence genes, with the exception of astA, was associated more generally with APEC strains. 5. Statistically, genes such as cva/cvi, tsh, iss, irp2 and iucD were more related to isolates from colibacillosis. 6. It is suggested that the detection of these genes in a rapid and inexpensive test for field practitioners could provide useful information about the potential virulence of E. coli isolated in commercial layer flocks. PMID:23130581

  17. Cloning and sequencing of the virulent gene LipL32 of Leptospira interrogans serovar Autumnalis

    OpenAIRE

    Sriram Vamshi Krishna; Siju Joseph; R Ambily; M. Mini; Liya Anto; Sheethal G Mohan

    2013-01-01

    Aim: To clone the virulent gene LipL32 of Leptospira interrogans serovar Autumnalis and to analyze the sequence with LipL32 gene of other pathogenic serovars of Leptopsira. Materials and Methods: Leptospira interrogans serovar Autumnalis procured from Leptospira research laboratory, Chennai was used in the study. Polymerase chain reaction (PCR) was carried out for amplifying LipL32 gene using the reported primers of Leptospira Kirschnerii. The PCR product was cloned into TA cloning vector and...

  18. Protective potency of clove oil and its transcriptional down-regulation of Aeromonas sobria virulence genes in African catfish (Clarias gariepinus L.).

    Science.gov (United States)

    Abd El-Hamid, M I; Abd El-Aziz, N K; Ali, H A

    2016-01-01

    Disease episodes of fish caused by Aeromonas species are moved to the top list of limiting problems worldwide. The present study was planned to verify the in vitro antibacterial activities as well as the in vivo potential values of clove oil and ciprofloxacin against Aeromonas sobria in African catfish (Clarias gariepinus). The in vitro phenotypic virulence activities and the successful amplification of aerolysin and hemolysin genes in the precisely identified A. sobria strain were predictive for its virulence. In the in vivo assay, virulence of A. sobria strain was fully demonstrated based on constituent mRNA expression profile of tested virulence genes and typical septicemia associated with high mortalities of infected fish. Apparent lower mortality rates were correlated well with both decrescent bacterial burden and significant down-regulated transcripts of representative genes in the treated groups with clove oil, followed by ciprofloxacin as a prophylactic use for 15 days (P oil apart from ciprofloxacin significantly enhanced different hematological parameters (P medicinal plants-derived essential oils provide a virtually safer alternative to chemotherapeutics on fish, consumers and ecosystems. PMID:27609474

  19. Detection of virulence genes (yrp1 and yrpE in the Yersinia ruckeri by polymerase chain reaction test in Chaharmahal-Va-Bakhtiary province, Iran

    Directory of Open Access Journals (Sweden)

    Firooz fadaeifard

    2014-04-01

    Full Text Available Introduction: Yersinia ruckeri is the etiological agent of enteric redmouth (ERM disease, one of the important bacterial diseases in the cultured salmonids. The aim of present study was detection of virulence genes (yrpE and yrp1 in the Y.ruckeri bacterium Materials and methods In this study fish were evaluated in average size 10-12 Cm from six rainbow trout farms in Chaharmahal-Va-Bakhtiary province. In each farm 10 fish (totally 60 suspected to ERM were randomly selected, sampling was done from lower part of intestine and cultured on general (trypticase soy agar and specific (Waltman-Shots mediums. Finally, colonies that were isolated on these mediums tested by PCR method for Y.ruckeri detection. Then, in the identified strains of Y.ruckeri virulenc genes (yrp1and yrpE were detected by PCR test. Results: In the all strains of Y.ruckeri two virulence genes (yrp1and yrpE were identified by molecular test. 24 strains out of total isolates were identified as Y.ruckeri, and among them 12 cases (50% and 11 cases (45.83% had yrp1 andyrpE genes, respectively. Also, 6 samples (25% had both genes simultaneously. Discussion and conclusion: The study revealed that virulence factor yrp1 is as extracellular protease presence in Y.ruckeri strains. This factor plays an important role in the bacterial virulence and pathogenesis of ERM disease. Data obtained in this study help to control disease especially in development of current vaccines.

  20. Inhibition of Virulence Gene Expression in Staphylococcus aureus by Novel Depsipeptides from a Marine Photobacterium

    Directory of Open Access Journals (Sweden)

    Lone Gram

    2011-12-01

    Full Text Available During a global research expedition, more than five hundred marine bacterial strains capable of inhibiting the growth of pathogenic bacteria were collected. The purpose of the present study was to determine if these marine bacteria are also a source of compounds that interfere with the agr quorum sensing system that controls virulence gene expression in Staphylococcus aureus. Using a gene reporter fusion bioassay, we recorded agr interference as enhanced expression of spa, encoding Protein A, concomitantly with reduced expression of hla, encoding α-hemolysin, and rnaIII encoding RNAIII, the effector molecule of agr. A marine Photobacterium produced compounds interfering with agr in S. aureus strain 8325-4, and bioassay-guided fractionation of crude extracts led to the isolation of two novel cyclodepsipeptides, designated solonamide A and B. Northern blot analysis confirmed the agr interfering activity of pure solonamides in both S. aureus strain 8325-4 and the highly virulent, community-acquired strain USA300 (CA-MRSA. To our knowledge, this is the first report of inhibitors of the agr system by a marine bacterium.

  1. A Bistable Switch and Anatomical Site Control Vibrio cholerae Virulence Gene Expression in the Intestine

    DEFF Research Database (Denmark)

    Nielsen, Alex Toftgaard; Dolganov, N. A.; Rasmussen, Thomas;

    2010-01-01

    A fundamental, but unanswered question in host-pathogen interactions is the timing, localization and population distribution of virulence gene expression during infection. Here, microarray and in situ single cell expression methods were used to study Vibrio cholerae growth and virulence gene expr...... expression during infection of the rabbit ligated ileal loop model of cholera. Genes encoding the toxin-coregulated pilus (TCP) and cholera toxin (CT) were powerfully expressed early in the infectious process in bacteria adjacent to epithelial surfaces. Increased growth was found to co......-localize with virulence gene expression. Significant heterogeneity in the expression of tcpA, the repeating subunit of TCP, was observed late in the infectious process. The expression of tcpA, studied in single cells in a homogeneous medium, demonstrated unimodal induction of tcpA after addition of bicarbonate......, a chemical inducer of virulence gene expression. Striking bifurcation of the population occurred during entry into stationary phase: one subpopulation continued to express tcpA, whereas the expression declined in the other subpopulation. ctxA, encoding the A subunit of CT, and toxT, encoding the proximal...

  2. Use of bacterially expressed dsRNA to downregulate Entamoeba histolytica gene expression.

    Directory of Open Access Journals (Sweden)

    Carlos F Solis

    Full Text Available BACKGROUND: Modern RNA interference (RNAi methodologies using small interfering RNA (siRNA oligonucleotide duplexes or episomally synthesized hairpin RNA are valuable tools for the analysis of gene function in the protozoan parasite Entamoeba histolytica. However, these approaches still require time-consuming procedures including transfection and drug selection, or costly synthetic molecules. PRINCIPAL FINDINGS: Here we report an efficient and handy alternative for E. histolytica gene down-regulation mediated by bacterial double-stranded RNA (dsRNA targeting parasite genes. The Escherichia coli strain HT115 which is unable to degrade dsRNA, was genetically engineered to produce high quantities of long dsRNA segments targeting the genes that encode E. histolytica beta-tubulin and virulence factor KERP1. Trophozoites cultured in vitro were directly fed with dsRNA-expressing bacteria or soaked with purified dsRNA. Both dsRNA delivery methods resulted in significant reduction of protein expression. In vitro host cell-parasite assays showed that efficient downregulation of kerp1 gene expression mediated by bacterial dsRNA resulted in significant reduction of parasite adhesion and lytic capabilities, thus supporting a major role for KERP1 in the pathogenic process. Furthermore, treatment of trophozoites cultured in microtiter plates, with a repertoire of eighty-five distinct bacterial dsRNA segments targeting E. histolytica genes with unknown function, led to the identification of three genes potentially involved in the growth of the parasite. CONCLUSIONS: Our results showed that the use of bacterial dsRNA is a powerful method for the study of gene function in E. histolytica. This dsRNA delivery method is also technically suitable for the study of a large number of genes, thus opening interesting perspectives for the identification of novel drug and vaccine targets.

  3. Erwinia amylovora expresses fast and simultaneously hrp/dsp virulence genes during flower infection on apple trees.

    Directory of Open Access Journals (Sweden)

    Doris Pester

    Full Text Available BACKGROUND: Pathogen entry through host blossoms is the predominant infection pathway of the gram-negative bacterium Erwinia amylovora leading to manifestation of the disease fire blight. Like in other economically important plant pathogens, E. amylovora pathogenicity depends on a type III secretion system encoded by hrp genes. However, timing and transcriptional order of hrp gene expression during flower infections are unknown. METHODOLOGY/PRINCIPAL FINDINGS: Using quantitative real-time PCR analyses, we addressed the questions of how fast, strong and uniform key hrp virulence genes and the effector dspA/E are expressed when bacteria enter flowers provided with the full defense mechanism of the apple plant. In non-invasive bacterial inoculations of apple flowers still attached to the tree, E. amylovora activated expression of key type III secretion genes in a narrow time window, mounting in a single expression peak of all investigated hrp/dspA/E genes around 24-48 h post inoculation (hpi. This single expression peak coincided with a single depression in the plant PR-1 expression at 24 hpi indicating transient manipulation of the salicylic acid pathway as one target of E. amylovora type III effectors. Expression of hrp/dspA/E genes was highly correlated to expression of the regulator hrpL and relative transcript abundances followed the ratio: hrpA>hrpN>hrpL>dspA/E. Acidic conditions (pH 4 in flower infections led to reduced virulence/effector gene expression without the typical expression peak observed under natural conditions (pH 7. CONCLUSION/SIGNIFICANCE: The simultaneous expression of hrpL, hrpA, hrpN, and the effector dspA/E during early floral infection indicates that speed and immediate effector transmission is important for successful plant invasion. When this delicate balance is disturbed, e.g., by acidic pH during infection, virulence gene expression is reduced, thus partly explaining the efficacy of acidification in fire blight

  4. Identification of two proteins that interact with the Erp virulence factor from Mycobacterium tuberculosis by using the bacterial two-hybrid system

    Directory of Open Access Journals (Sweden)

    Cataldi Angel A

    2009-01-01

    Full Text Available Abstract Background The exported repetitive protein (erp gene encodes a secreted 36-kDa protein with a central domain containing several proline-glycine-leucine-threonine-serine (PGLTS repeats. It has been demonstrated that erp is a virulence-associated factor since the disruption of this gene impairs the growth of Mycobacterium bovis and Mycobacterium tuberculosis in mice. Results In order to elucidate the function of Erp we searched for Erp-binding proteins from M. tuberculosis by using a bacterial two-hybrid system. Our results indicate that Erp interacts specifically with two putative membrane proteins, Rv1417 and Rv2617c. Further analysis revealed that the latter two interact with each other, indicating that Rv1417, Rv2617c and Erp are connected through multiple interactions. While Rv1417 is disseminated in several Actinomycetales genera, orthologues of Rv2617c are exclusively present in members of the M. tuberculosis complex (MTC. The central and amino-terminal regions of Erp were determined to be involved in the interaction with Rv1417 and Rv2627c. Erp forms from Mycobacterium smegmatis and Mycobacterium leprae were not able to interact with Rv2617c in two-hybrid assays. Immunolocalization experiments showed that Rv1417 and Rv2617c are found on the cell membrane and Erp on the bacterial cell wall. Finally, comparative genomics and expression studies revealed a possible role of Rv1417 in riboflavin metabolism. Conclusion We identified interactive partners of Erp, an M. tuberculosis protein involved in virulence, which will be the focus of future investigation to decipher the function of the Erp family protein.

  5. The HopQ1 effector's nucleoside hydrolase-like domain is required for bacterial virulence in arabidopsis and tomato, but not host recognition in tobacco.

    Directory of Open Access Journals (Sweden)

    Wei Li

    Full Text Available Bacterial pathogens deliver multiple effector proteins into host cells to facilitate bacterial growth. HopQ1 is an effector from Pseudomonas syringae pv. tomato DC3000 that is conserved across multiple bacterial pathogens which infect plants. HopQ1's central region possesses some homology to nucleoside hydrolases, but possesses an alternative aspartate motif not found in characterized enzymes. A structural model was generated for HopQ1 based on the E. coli RihB nucleoside hydrolase and the role of HopQ1's potential catalytic residues for promoting bacterial virulence and recognition in Nicotiana tabacum was investigated. Transgenic Arabidopsis plants expressing HopQ1 exhibit enhanced disease susceptibility to DC3000. HopQ1 can also promote bacterial virulence on tomato when naturally delivered from DC3000. HopQ1's nucleoside hydrolase-like domain alone is sufficient to promote bacterial virulence, and putative catalytic residues are required for virulence promotion during bacterial infection of tomato and in transgenic Arabidopsis lines. HopQ1 is recognized and elicits cell death when transiently expressed in N. tabacum. Residues required to promote bacterial virulence were dispensable for HopQ1's cell death promoting activities in N. tabacum. Although HopQ1 has some homology to nucleoside hydrolases, we were unable to detect HopQ1 enzymatic activity or nucleoside binding capability using standard substrates. Thus, it is likely that HopQ1 promotes pathogen virulence by hydrolyzing alternative ribose-containing substrates in planta.

  6. Phosphorylation Events in the Multiple Gene Regulator of Group A Streptococcus Significantly Influence Global Gene Expression and Virulence

    OpenAIRE

    Sanson, Misu; Makthal, Nishanth; Gavagan, Maire; Cantu, Concepcion; Olsen, Randall J.; Musser, James M.; Kumaraswami, Muthiah

    2015-01-01

    Whole-genome sequencing analysis of ∼800 strains of group A Streptococcus (GAS) found that the gene encoding the multiple virulence gene regulator of GAS (mga) is highly polymorphic in serotype M59 strains but not in strains of other serotypes. To help understand the molecular mechanism of gene regulation by Mga and its contribution to GAS pathogenesis in serotype M59 GAS, we constructed an isogenic mga mutant strain. Transcriptome studies indicated a significant regulatory influence of Mga a...

  7. Identification and functional analysis of Penicillium digitatum genes putatively involved in virulence towards citrus fruit.

    Science.gov (United States)

    López-Pérez, Mario; Ballester, Ana-Rosa; González-Candelas, Luis

    2015-04-01

    The fungus Penicillium digitatum, the causal agent of green mould rot, is the most destructive post-harvest pathogen of citrus fruit in Mediterranean regions. In order to identify P. digitatum genes up-regulated during the infection of oranges that may constitute putative virulence factors, we followed a polymerase chain reaction (PCR)-based suppression subtractive hybridization and cDNA macroarray hybridization approach. The origin of expressed sequence tags (ESTs) was determined by comparison against the available genome sequences of both organisms. Genes coding for fungal proteases and plant cell wall-degrading enzymes represent the largest categories in the subtracted cDNA library. Northern blot analysis of a selection of P. digitatum genes, including those coding for proteases, cell wall-related enzymes, redox homoeostasis and detoxification processes, confirmed their up-regulation at varying time points during the infection process. Agrobacterium tumefaciens-mediated transformation was used to generate knockout mutants for two genes encoding a pectin lyase (Pnl1) and a naphthalene dioxygenase (Ndo1). Two independent P. digitatum Δndo1 mutants were as virulent as the wild-type. However, the two Δpnl1 mutants analysed were less virulent than the parental strain or an ectopic transformant. Together, these results provide a significant advance in our understanding of the putative determinants of the virulence mechanisms of P. digitatum. PMID:25099378

  8. Sheeppox virus kelch-like gene SPPV-019 affects virus virulence

    Science.gov (United States)

    Sheeppox virus (SPPV), a member of the Capripoxvirus genus of the Poxviridae, is the etiologic agent of a significant disease of sheep in the developing world. Genomic analysis of pathogenic and vaccine capripoxviruses identified genes with potential roles in virulence and host-range, including thr...

  9. PfSETvs methylation of histone H3K36 represses virulence genes in Plasmodium falciparum

    DEFF Research Database (Denmark)

    Jiang, Lubin; Mu, Jianbing; Zhang, Qingfeng;

    2013-01-01

    The variant antigen Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), which is expressed on the surface of P. falciparum-infected red blood cells, is a critical virulence factor for malaria. Each parasite has 60 antigenically distinct var genes that each code for a different PfEMP1...

  10. Trophozoites of Entamoeba histolytica epigenetically silenced in several genes are virulence-attenuated

    Directory of Open Access Journals (Sweden)

    Mirelman D.

    2008-09-01

    Full Text Available The human intestinal parasite Entamoeba histolytica causes amoebic colitis and amoebic liver abscesses. Three classes of amoebic molecules have been identified as the major virulence factors, the Gal/GalNAc inhibitable lectin that mediates adherence to mammalian cells, the amoebapores which cause the formation of membrane ion channels in the target cells and the cysteine proteinases which degrade the matrix proteins, the intestinal mucus and secretory IgA. Transcriptional silencing of the amoebapore (Ehap-a gene occurred after transfection of trophozoites with a plasmid containing a segment of the 5’ upstream region of the gene. Transcriptional silencing of the Ehap-a gene continued even after the removal of the plasmid and the cloned amoebae were termed G3. Transfection of G3 trophozoites with a plasmid construct containing the cysteine proteinase (EhCP-5 gene and the light subunit of the Gal- lectin (Ehlgl1 gene, each under the 5’ upstream sequences of the amoebapore gene, caused the simultaneous epigenetic silencing of expression of these two genes. The resulting trophozoites, termed RB-9, were cured from the plasmid and they do not express the three types of virulent genes. The RB-9 amoeba are virulence attenuated and are incapable of killing mammalian cells, they can not induce the formation of liver abscesses and they do not cause ulcerations in the cecum of experimental animals. The gene-silenced amoebae express the same surface antigens which are present in virulent strains and following intra peritoneal inoculation of live trophozoites into hamsters they evoked a protective immune response. Further studies are needed to find out if RB-9 trophozoites could be used for vaccination against amoebaisis.

  11. Analysis of subtelomeric virulence gene families in Plasmodium falciparum by comparative transcriptional profiling.

    Science.gov (United States)

    Witmer, Kathrin; Schmid, Christoph D; Brancucci, Nicolas M B; Luah, Yen-Hoon; Preiser, Peter R; Bozdech, Zbynek; Voss, Till S

    2012-04-01

    The Plasmodium falciparum genome is equipped with several subtelomeric gene families that are implicated in parasite virulence and immune evasion. Members of these families are uniformly positioned within heterochromatic domains and are thus subject to variegated expression. The best-studied example is that of the var family encoding the major parasite virulence factor P. falciparum erythrocyte membrane protein 1 (PfEMP1). PfEMP1 undergoes antigenic variation through switches in mutually exclusive var gene transcription. var promoters function as crucial regulatory elements in the underlying epigenetic control strategy. Here, we analysed promoters of upsA, upsB and upsC var, rifA1-type rif, stevor, phist and pfmc-2tm genes and investigated their role in endogenous gene transcription by comparative genome-wide expression profiling of transgenic parasite lines. We find that the three major var promoter types are functionally equal and play an essential role in singular gene choice. Unlike var promoters, promoters of non-var families are not silenced by default, and transcription of non-var families is not subject to the same mode of mutually exclusive transcription as has been observed for var genes. Our findings identified a differential logic in the regulation of var and other subtelomeric virulence gene families, which will have important implications for our understanding and future analyses of phenotypic variation in malaria parasites. PMID:22435676

  12. Distinct Expression Levels of ALS, LIP, and SAP Genes in Candida tropicalis with Diverse Virulent Activities.

    Science.gov (United States)

    Yu, Shuanbao; Li, Wenge; Liu, Xiaoshu; Che, Jie; Wu, Yuan; Lu, Jinxing

    2016-01-01

    Candia tropicalis is an increasingly important human pathogen, causing nosocomial fungemia among patients with neutropenia or malignancy. However, limited research has been published concerning its pathogenicity. Based on the phenotypes of C. tropicalis in our previous study, we selected nine representative strains with different activities of virulence factors (adhesion, biofilm formation, secreted aspartic proteinases, and hemolysins), and one reference strain, ATCC750. The present study aimed to investigate the filamentation ability, the expression of virulence genes (ALST1-3, LIP1, LIP4, and SAPT1-4) and the cell damage of C. tropicalis strains with diverse virulences. C. tropicalis exhibited strain-dependent filamentation ability, which was positively correlated with biofilm formation. Reverse transcriptase PCR analysis showed that the ALST3 and SAPT3 genes had the highest expression in their corresponding genes for most C. tropicalis. The expressions of virulence genes, except ALST3 on polystyrene, were upregulated compared with growth in the planktonic and on human urinary bladder epithelial cell line (TCC-SUP) surface. Clustering analysis of virulence genes showed that isolates had a high biofilm forming ability on polystyrene formed a group. Lactate dehydrogenase assays showed that the cell damage induced by C. tropicalis markedly increased with longer infection time (24 and 48 h). Strain FXCT01, isolated from blood, caused the most serious cell damage; while ZRCT52, which had no filamentation ability, caused the least cell damage. Correlation analysis demonstrated significant correlation existed between adhesion on epithelial cells or the expression of ALST2-3 and cell damage. Overall, our results supported the view that adhesion and filamentation may play significant roles in the cell damage caused by C. tropicalis. PMID:27524980

  13. H-NS is a repressor of major virulence gene loci in Vibrio parahaemolyticus

    Directory of Open Access Journals (Sweden)

    Dongsheng eZhou

    2014-12-01

    Full Text Available Vibrio parahaemolyticus, a leading cause of seafood-associated diarrhea and gastroenteritis, harbors three major virulence gene loci T3SS1, Vp-PAI (T3SS1+tdh2 and T6SS2. As showing is this study, the nucleoid-associated DNA-binding regulator H-NS binds to multiple promoter-proximal regions in each of the above three loci to repress their transcription, and moreover H-NS inhibits the cytotoxicitiy, enterotoxicity, hemolytic activity, and mouse lethality of V. parahaemolyticus. H-NS appears to act as a major repressor of the virulence of this pathogen.

  14. Genome sequencing of a virulent avian Pasteurella multocida strain GX-Pm reveals the candidate genes involved in the pathogenesis.

    Science.gov (United States)

    Yu, Chengjie; Sizhu, Suolang; Luo, Qingping; Xu, Xuewen; Fu, Lei; Zhang, Anding

    2016-04-01

    Pasteurella multocida (P. multocida) was first shown to be the causative agent of fowl cholera by Louis Pasteur in 1881. First genomic study was performed on an avirulent avian strain Pm70, and until 2013, two genomes of virulent avian strains X73 and P1059 were sequenced. Comparative genome study supplied important information for further study on the pathogenesis of fowl cholera. In the previous study, a capsular serotype A strain GX-Pm was isolated from the liver of a chicken, which died during an outbreak of fowl cholera in 2011. The strain showed multiple drug resistance and was highly virulent to chickens. Therefore, the present study performed the genome sequencing and a comparative genomic analysis to reveal the candidate genes involved in virulence of P. multocida. Sequenced draft genome sequence of GX-Pm was 2,292,886 bp, contained 2941 protein-coding genes, 5 genomic islands, 4 IS elements and 2 prophage regions. Notability, all the predicted drug-resistance genes were included in predicted genomic islands. A comparative genome study on virulent avian strains P1059, X73 and GX-Pm with the avirulent avian strain Pm 70 indicated that 475 unique genes were only identified in either of virulent strains but absent in the avirulent strain. Among these genes, 20 genes were contained within genomes of all three virulent strains, including a few of putative virulence genes. Further characterization of the pathogenic functions of these genes would benefit the understanding of pathogenesis of fowl cholera. PMID:27033902

  15. Differential expression of pathogenicity- and virulence-related genes of Xanthomonas axonopodis pv. citri under copper stress

    Directory of Open Access Journals (Sweden)

    Ana Carolina Basílio Palmieri

    2010-01-01

    Full Text Available In this study, we used real-time quantitative PCR (RT-qPCR to evaluate the expression of 32 genes of Xanthomonas axonopodis pv. citri related to pathogenicity and virulence that are also involved in copper detoxification. Nearly all of the genes were up-regulated, including copA and copB. Two genes homologous to members of the type II secretion system (xcsH and xcsC and two involved in the degradation of plant cell wall components (pglA and pel were the most expressed in response to an elevated copper concentration. The type II secretion system (xcs operon and a few homologues of proteins putatively secreted by this system showed enhanced expression when the bacteria were exposed to a high concentration of copper sulfate. The enhanced expression of the genes of secretion II system during copper stress suggests that this pathway may have an important role in the adaptative response of X. axonopodis pv. citri to toxic compounds. These findings highlight the potential role of these genes in attenuating the toxicity of certain metals and could represent an important means of bacterial resistance against chemicals used to control diseases.

  16. Host PGRP gene expression and bacterial release in endosymbiosis of the weevil Sitophilus zeamais.

    Science.gov (United States)

    Anselme, Caroline; Vallier, Agnès; Balmand, Séverine; Fauvarque, Marie-Odile; Heddi, Abdelaziz

    2006-10-01

    Intracellular symbiosis (endosymbiosis) with gram-negative bacteria is common in insects, yet little is known about how the host immune system perceives the endosymbionts and controls their growth and invasion without complete bacterial clearance. In this study, we have explored the expression of a peptidoglycan recognition protein gene of the weevil Sitophilus zeamais (wPGRP); an ortholog in Drosophila (i.e., PGRP-LB) was recently shown to downregulate the Imd pathway (A. Zaidman-Remy, M. Herve, M. Poidevin, S. Pili-Floury, M. S. Kim, D. Blanot, B. H. Oh, R. Ueda, D. Mengin-Lecreulx, and B. Lemaitre, Immunity 24:463-473, 2006). Insect challenges with bacteria have demonstrated that wPGRP is induced by gram-negative bacteria and that the level of induction depends on bacterial growth. Real-time reverse transcription-PCR quantification of the wPGRP gene transcript performed at different points in insect development has shown a high steady-state level in the bacteria-bearing organ (the bacteriome) of larvae and a high level of wPGRP up-regulation in the symbiotic nymphal phase. Concomitantly, during this stage fluorescence in situ hybridization has revealed an endosymbiont release from the host bacteriocytes. Together with the previously described high induction level of endosymbiont virulence genes at the nymphal phase (C. Dale, G. R. Plague, B. Wang, H. Ochman, and N. A. Moran, Proc. Natl. Acad. Sci. USA 99:12397-12402, 2002), these findings indicate that insect mutualistic relationships evolve through an interplay between bacterial virulence and host immune defense and that the host immunity engages the PGRP gene family in that interplay. PMID:17021229

  17. [Using Galleria mellonella as an in vivo model to study the virulence of some bacterial and fungal agents].

    Science.gov (United States)

    Kalkancı, Ayşe; Fouad, Ali Adil; Erdoğan, Merve; Altay, Aylin; Aliyeva, Zemfira; Bozdayı, Gülendam; Çağlar, Kayhan

    2015-07-01

    Non-vertebrate hosts, such as Galleria mellonella, namely wax moth, have been used to study microbial virulence and host defense. This organism has advantages as it is economical, ethically expedient and easy to handle. Here we describe an experimental in vivo study using the larvae of Galleria mellonella infected with some bacterial and fungal pathogens. In this study, extended-spectrum beta-lactamase (ESBL) producing and non-producing Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa, colistin resistant and susceptible Acinetobacter baumanii clinical strains; Candida albicans (ATCC 10231), Scedosporium aurantiacum (CBS 136047) and Pseudallescheria boydii (CBS 117410) reference strains, and Aspergillus terreus and Fusarium oxysporum clinical strains were used as pathogens. The larvae of G.mellonella were challenged with these bacterial and fungal strains, and the mortality rates were calculated using Kaplan-Meier plots. Mortality rates at 16th hour were found as 83% for the larvae infected with both ESBL positive and negative E.coli, ESBL negative K.pneumoniae and ESBL positive P.aeruginosa; 91% for ESBL positive K.pneumoniae; 75% for ESBL negative P.aeruginosa; 66% for both colistin resistant and susceptible A.baumanii strains. All larvae infected with bacteria died within the first 24 hour. Larvae infected with bacteria showed significantly higher mortality rates than those infected with fungi. Mortality rates at 16th hour were found as 0% for C.albicans and F.oxysporum, 16% for S.aurantiacum, 8% for P.boydii and A.terreus; at 24th hour that was 25% for C.albicans and P.boydii, 33% for S.aurantiacum, A.terreus and F.oxysporum; at 48th hour that was 33% for C.albicans, 50% for P.boydii and F.oxysporum, 58% for A.terreus, and 66% for S.aurantiacum; in 72 hours that was 58% for C.albicans and F.oxysporum, 66% for P.boydii, 75% for A.terreus and S.aurantiacum, in 96 hours that was 83% for C.albicans, P.boydii and F.oxysporum, 91% for A.terreus and S

  18. An In Vivo Selection Identifies Listeria monocytogenes Genes Required to Sense the Intracellular Environment and Activate Virulence Factor Expression.

    Science.gov (United States)

    Reniere, Michelle L; Whiteley, Aaron T; Portnoy, Daniel A

    2016-07-01

    Listeria monocytogenes is an environmental saprophyte and facultative intracellular bacterial pathogen with a well-defined life-cycle that involves escape from a phagosome, rapid cytosolic growth, and ActA-dependent cell-to-cell spread, all of which are dependent on the master transcriptional regulator PrfA. The environmental cues that lead to temporal and spatial control of L. monocytogenes virulence gene expression are poorly understood. In this study, we took advantage of the robust up-regulation of ActA that occurs intracellularly and expressed Cre recombinase from the actA promoter and 5' untranslated region in a strain in which loxP sites flanked essential genes, so that activation of actA led to bacterial death. Upon screening for transposon mutants that survived intracellularly, six genes were identified as necessary for ActA expression. Strikingly, most of the genes, including gshF, spxA1, yjbH, and ohrA, are predicted to play important roles in bacterial redox regulation. The mutants identified in the genetic selection fell into three broad categories: (1) those that failed to reach the cytosolic compartment; (2) mutants that entered the cytosol, but failed to activate the master virulence regulator PrfA; and (3) mutants that entered the cytosol and activated transcription of actA, but failed to synthesize it. The identification of mutants defective in vacuolar escape suggests that up-regulation of ActA occurs in the host cytosol and not the vacuole. Moreover, these results provide evidence for two non-redundant cytosolic cues; the first results in allosteric activation of PrfA via increased glutathione levels and transcriptional activation of actA while the second results in translational activation of actA and requires yjbH. Although the precise host cues have not yet been identified, we suggest that intracellular redox stress occurs as a consequence of both host and pathogen remodeling their metabolism upon infection. PMID:27414028

  19. Proteomic analysis of growth phase-dependent expression of Legionella pneumophila proteins which involves regulation of bacterial virulence traits.

    Directory of Open Access Journals (Sweden)

    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.

  20. Mycobacterium tuberculosis nuoG is a virulence gene that inhibits apoptosis of infected host cells.

    Directory of Open Access Journals (Sweden)

    Kamalakannan Velmurugan

    2007-07-01

    Full Text Available The survival and persistence of Mycobacterium tuberculosis depends on its capacity to manipulate multiple host defense pathways, including the ability to actively inhibit the death by apoptosis of infected host cells. The genetic basis for this anti-apoptotic activity and its implication for mycobacterial virulence have not been demonstrated or elucidated. Using a novel gain-of-function genetic screen, we demonstrated that inhibition of infection-induced apoptosis of macrophages is controlled by multiple genetic loci in M. tuberculosis. Characterization of one of these loci in detail revealed that the anti-apoptosis activity was attributable to the type I NADH-dehydrogenase of M. tuberculosis, and was mainly due to the subunit of this multicomponent complex encoded by the nuoG gene. Expression of M. tuberculosis nuoG in nonpathogenic mycobacteria endowed them with the ability to inhibit apoptosis of infected human or mouse macrophages, and increased their virulence in a SCID mouse model. Conversely, deletion of nuoG in M. tuberculosis ablated its ability to inhibit macrophage apoptosis and significantly reduced its virulence in mice. These results identify a key component of the genetic basis for an important virulence trait of M. tuberculosis and support a direct causal relationship between virulence of pathogenic mycobacteria and their ability to inhibit macrophage apoptosis.

  1. Detection of virulence genes in Salmonella Enteritidis isolated from different sources Detecção de genes de virulência in Salmonella Enteritidis isoladas de diferentes fontes

    OpenAIRE

    Sílvia Dias de Oliveira; Carla Rosane Rodenbusch; Geovana B. Michael; Marisa I.R. Cardoso; Cláudio Wageck Canal; Adriano Brandelli

    2003-01-01

    The presence of three virulence genes, invA, spvR, and spvC, was determined in Salmonella Enteritidis isolated from poultry, pigs, humans and food. All isolates were positive for the invA gene, with 91.2% being positive for spvR and 90.2% for spvC. There was no significant difference in the prevalence of the virulence genes between isolates from different sources. The results indicate that there is a putative high virulence potential for the S. Enteritidis isolates characterized.A presença de...

  2. Lineage specific recombination and positive selection in coding and intragenic regions contributed to evolution of the main Listeria monocytogenes virulence gene cluster

    OpenAIRE

    Orsi, Renato H.; Maron, Steven B.; Nightingale, Kendra K.; Jerome, Morganne; Tabor, Helen; Wiedmann, Martin

    2008-01-01

    The major virulence cluster of Listeria monocytogenes harbors six virulence genes that encode proteins critical for the intracellular life cycle of this human and animal pathogen. In this study, we determined the sequence (8,709 nt) of the virulence gene cluster (including the six main virulence genes) in 40 L. monocytogenes isolates from different source populations (human clinical cases, animal clinical cases, foods, and natural environments). An alignment of the full length cluster as well...

  3. Prevalence of Campylobacter species in milk and milk products, their virulence gene profile and antibiogram

    Directory of Open Access Journals (Sweden)

    Shivani Modi

    2015-01-01

    Full Text Available Aim: During the last decades, number of food poisoning cases due to Campylobacter occurred, immensely. After poultry, raw milk acts as a second main source of Campylobacter. Therefore, the present study was undertaken to detect the prevalence of Campylobacters in milk and milk products and to know the antibiotic sensitivity and virulence gene profile of Campylobacter spp. in Anand city, Gujarat, India. Materials and Methods: A total of 240 samples (85 buffalo milk, 65 cow milk, 30 cheese, 30 ice-cream and 30 paneer were collected from the different collection points in Anand city. The samples were processed by microbiological culture method, and presumptive isolates were further confirmed by genus and species-specific polymerase chain reaction using previously reported primer. The isolates were further subjected to antibiotic susceptibility assay and virulence gene detection. Result: Campylobacter species were detected in 7 (2.91% raw milk samples whereas none of the milk product was positive. All the isolate identified were Campylobacter jejuni. Most of the isolates showed resistance against nalidixic acid, ciprofloxacin, and tetracyclin. All the isolates have three virulence genes cadF, cdtB and flgR whereas only one isolate was positive for iamA gene and 6 isolates were positive for fla gene. Conclusion: The presence of Campylobacter in raw milk indicates that raw milk consumption is hazardous for human being and proper pasteurization of milk and adaptation of hygienic condition will be necessary to protect the consumer from this zoonotic pathogen.

  4. Broiler chickens, broiler chicken meat, pigs and pork as sources of ExPEC related virulence genes and resistance in Escherichia coli isolates from community-dwelling humans and UTI patients

    DEFF Research Database (Denmark)

    Jakobsen, L; Spangholm, D. J.; Pedersen, Karl;

    2010-01-01

    Urinary tract infection (UTI) is one of the most common bacterial infections. UTI is primarily caused by extraintestinal pathogenic Escherichia coli (ExPEC) from the patients' own fecal flora. The ExPEC often belong to phylogroups B2 and D, the groups which include potent human ExPEC isolates......PEC related virulence genes in E. coli isolates from UTI patients, community-dwelling humans, meat, and production animals. Accordingly, we included 964 geographically and temporally matched E. coli isolates from UTI patients (n=102), community-dwelling humans (n=109), fresh Danish (n=197) and imported...... meat, broiler chickens, pork and pigs could be the source of strains with these ExPEC related virulence genes in community-dwelling humans and UTI patients. Especially detection of ExPEC related virulence genes in isolates belonging to phylogroups B2 and D is very concerning and may have a significant...

  5. The global response regulator ExpA controls virulence gene expression through RsmA-mediated and RsmA-independent pathways in Pectobacterium wasabiae SCC3193.

    Science.gov (United States)

    Broberg, M; Lee, G W; Nykyri, J; Lee, Y H; Pirhonen, M; Palva, E T

    2014-03-01

    ExpA (GacA) is a global response regulator that controls the expression of major virulence genes, such as those encoding plant cell wall-degrading enzymes (PCWDEs) in the model soft rot phytopathogen Pectobacterium wasabiae SCC3193. Several studies with pectobacteria as well as related phytopathogenic gammaproteobacteria, such as Dickeya and Pseudomonas, suggest that the control of virulence by ExpA and its homologues is executed partly by modulating the activity of RsmA, an RNA-binding posttranscriptional regulator. To elucidate the extent of the overlap between the ExpA and RsmA regulons in P. wasabiae, we characterized both regulons by microarray analysis. To do this, we compared the transcriptomes of the wild-type strain, an expA mutant, an rsmA mutant, and an expA rsmA double mutant. The microarray data for selected virulence-related genes were confirmed through quantitative reverse transcription (qRT-PCR). Subsequently, assays were performed to link the observed transcriptome differences to changes in bacterial phenotypes such as growth, motility, PCWDE production, and virulence in planta. An extensive overlap between the ExpA and RsmA regulons was observed, suggesting that a substantial portion of ExpA regulation appears to be mediated through RsmA. However, a number of genes involved in the electron transport chain and oligogalacturonide metabolism, among other processes, were identified as being regulated by ExpA independently of RsmA. These results suggest that ExpA may only partially impact fitness and virulence via RsmA. PMID:24441162

  6. The majority of genes in the pathogenic Neisseria species are present in non-pathogenic Neisseria lactamica, including those designated as virulence genes: response

    Directory of Open Access Journals (Sweden)

    Hinds Jason

    2006-05-01

    Full Text Available Abstract A response to Snyder LA, Saunders NJ: The majority of genes in the pathogenic Neisseria species are present in non-pathogenic Neisseria lactamica, including those designated as virulence genes. BMC Genomics 2006, 7:128.

  7. Virulence gene profiles in Staphylococcus aureus isolated from cows with subclinical mastitis in eastern Poland.

    Science.gov (United States)

    Kot, Barbara; Szweda, Piotr; Frankowska-Maciejewska, Aneta; Piechota, Małgorzata; Wolska, Katarzyna

    2016-05-01

    Staphylococcus aureus is arguably the most important pathogen involved in bovine mastitis. The aim of this study was to determine the virulence gene profiles of 124 Staph. aureus isolates from subclinical mastitis in cows in eastern Poland. The presence of 30 virulence genes encoding adhesins, proteases and superantigenic toxins was investigated by PCR. The 17 different combinations of adhesin genes were identified. Occurrence of eno (91·1%) and fib (82·3%) genes was found to be common. The frequency of other adhesion genes fnbA, fnbB, ebps were 14·5, 50, 25%, respectively, and for cna and bbp were 1·6%. The etA and etD genes, encoding exfoliative toxins, were present in genomes of 5·6 and 8·9% isolates, respectively. The splA and sspA, encoding serine protease, were detected in above 90% isolates. The most frequent enterotoxin genes were sei (21%), sem (19·4%), sen (19·4%), seg (18·5%) and seo (13·7%). The tst gene was harboured by 2·4% isolates. The 19 combinations of the superantigenic toxin genes were obtained and found in 35·5% of isolates. Three of them (seg, sei, sem, sen, seo; sec, seg, sei, sem, sen, seo and seg, sei, sem, sen) were the most frequent and found in 16·1% of the isolates. The most common virulotype, present in 17·7% of the isolates, was fib, eno, fnbB, splA, splE, sspA. The results indicate the variation in the presence of virulence genes in Staph. aureus isolates and considerable diversity of isolates that are able to cause mastitis in cows. PMID:27032339

  8. Role of bacterial virulence proteins in Agrobacterium-mediated transformation of Aspergillus awamori

    NARCIS (Netherlands)

    Michielse, C.B.; Ram, A.F.J.; Hooykaas, P.J.J.; Hondel, C.A.M.J.J. van den

    2004-01-01

    The Agrobacterium-mediated transformation of Aspergillus awamori was optimized using defined co-cultivation conditions, which resulted in a reproducible and efficient transformation system. Optimal co-cultivation conditions were used to study the role of Agrobacterium tumefaciens virulence proteins

  9. Bacterial determinants of importance in the virulence of Gallibacterium anatis in poultry

    DEFF Research Database (Denmark)

    Persson, Gry; Bojesen, Anders Miki

    2015-01-01

    immunoglobulins, and hemagglutinins, which may promote biofilm formation are all factors likely linked to the virulence of G. anatis. A major advantage for the study of how G. anatis interact with its host is the ability to perform biologically relevant experimental infections where natural routes of exposure...

  10. Detection and distribution of putative virulence associated genes in Aeromonas species from freshwater and wastewater treatment plant.

    Science.gov (United States)

    Igbinosa, Isoken H; Okoh, Anthony I

    2013-11-01

    The detection of genes responsible for Aeromonas virulence is a vital tool in establishing the potential pathogenicity of the bacteria, as these virulence genes may act alone or in synergy in the establishment of infections. Freshwater and wastewater mixed liquor samples were collected from Kat river and Fort Beaufort wastewater treatment plant in the Eastern Cape Province of South Africa. Polymerase chain reaction was utilized for the amplification of the different genes coding for virulence. All virulence associated genes screened (alt, lip, fla, aer, ast, hlyA) were detected in at least one Aeromonas isolates. In fresh water sample, virulence genes were distributed as follows: lip (67%), aer (43%), alt (33%), fla (62%), ast (10%), and hlyA (86%), while in wastewater samples the occurrence were as follows: lip (92%), aer (21%), alt (54%), fla (83%), ast (29%), and hlyA (88%). The presence of these virulence genes in environmental Aeromonas isolates is of concern to public health as these organisms are potential pathogens in the environment and the virulence determinants could be transferred to aquatic organisms and humans by one mechanism or the other. PMID:23322604

  11. Genome-wide mining of potential virulence-associated genes in Riemerella anatipestifer using random transposon mutagenesis.

    Science.gov (United States)

    Ni, Xintao; Jiang, Pan; Xing, Linlin; Ou, Changcan; Yu, Hui; Qi, Jingjing; Sun, Bingqing; Cui, Junsheng; Wang, Guijun; Hu, Qinghai

    2016-06-30

    Riemerella anatipestifer infection is a severe disease confronting the duck industry worldwide. However, little is known about the molecular basis of R. anatipestifer pathogenesis. In this study, we screened 3580 transposon Tn4351 insertion mutagenesis mutants of the highly virulent strain YZb1 in a duckling infection experiment and found 29 of them to be attenuated and 28 potential virulence-associated genes were identified. Molecular characterization of transposon insertion sites showed that of the 28 screened genes, two were predicted to encode TonB-dependent outer membrane receptor (plugs), sixteen encoded enzymes, and seven encoded hypothetical proteins. In addition, of the 28 affected genes, 19 were only found in bacteria belonging to the phylum Bacteroidetes and 10 were only found in the family Flavobacteriaceae. The median lethal dose of the mutants M11 and M29, which was affected in Riean_0060 and Riean_1537 respectively, were about 1700-fold and 210-fold higher than that of the wild-type strain YZb1, and those of the complemented strains M11(pRES-Riean_0060) and M29(pRES-Riean_1537) were decreased by 25- and 3-fold respectively compared to those of the mutants M11 and M29. Additional analysis indicated that the blood bacterial loading of ducklings infected with M11 or M29 was decreased significantly, as compared with that in ducklings infected with the wild-type strain YZb1. Thus, our results indicate that Riean_0060 and Riean_1537 were involved in R. anatipestifer pathogenesis. PMID:27259827

  12. Siderophore-mediated iron acquisition influences motility and is required for full virulence of the xylem-dwelling bacterial phytopathogen Pantoea stewartii subsp. stewartii.

    Science.gov (United States)

    Burbank, Lindsey; Mohammadi, Mojtaba; Roper, M Caroline

    2015-01-01

    Iron is a key micronutrient for microbial growth but is often present in low concentrations or in biologically unavailable forms. Many microorganisms overcome this challenge by producing siderophores, which are ferric-iron chelating compounds that enable the solubilization and acquisition of iron in a bioactive form. Pantoea stewartii subsp. stewartii, the causal agent of Stewart's wilt of sweet corn, produces a siderophore under iron-limiting conditions. The proteins involved in the biosynthesis and export of this siderophore are encoded by the iucABCD-iutA operon, which is homologous to the aerobactin biosynthetic gene cluster found in a number of enteric pathogens. Mutations in iucA and iutA resulted in a decrease in surface-based motility that P. stewartii utilizes during the early stages of biofilm formation, indicating that active iron acquisition impacts surface motility for P. stewartii. Furthermore, bacterial movement in planta is also dependent on a functional siderophore biosynthesis and uptake pathway. Most notably, siderophore-mediated iron acquisition is required for full virulence in the sweet corn host, indicating that active iron acquisition is essential for pathogenic fitness for this important xylem-dwelling bacterial pathogen. PMID:25326304

  13. In silico phylogenetic and virulence gene profile analyses of avian pathogenic Escherichia coli genome sequences

    Directory of Open Access Journals (Sweden)

    Thaís C.G. Rojas

    2014-02-01

    Full Text Available Avian pathogenic Escherichia coli (APEC infections are responsible for significant losses in the poultry industry worldwide. A zoonotic risk has been attributed to APEC strains because they present similarities to extraintestinal pathogenic E. coli (ExPEC associated with illness in humans, mainly urinary tract infections and neonatal meningitis. Here, we present in silico analyses with pathogenic E. coli genome sequences, including recently available APEC genomes. The phylogenetic tree, based on multi-locus sequence typing (MLST of seven housekeeping genes, revealed high diversity in the allelic composition. Nevertheless, despite this diversity, the phylogenetic tree was able to cluster the different pathotypes together. An in silico virulence gene profile was also determined for each of these strains, through the presence or absence of 83 well-known virulence genes/traits described in pathogenic E. coli strains. The MLST phylogeny and the virulence gene profiles demonstrated a certain genetic similarity between Brazilian APEC strains, APEC isolated in the United States, UPEC (uropathogenic E. coli and diarrheagenic strains isolated from humans. This correlation corroborates and reinforces the zoonotic potential hypothesis proposed to APEC.

  14. Role of mga in growth phase regulation of virulence genes of the group A streptococcus.

    OpenAIRE

    McIver, K S; J. R. Scott

    1997-01-01

    To determine whether growth phase affects the expression of mga and other virulence-associated genes in the group A streptococcus (GAS), total RNA was isolated from the serotype M6 GAS strain JRS4 at different phases of growth and transcript levels were quantitated by hybridization with radiolabeled DNA probes. Expression of mga (which encodes a multiple gene regulator) and the Mga-regulated genes emm (which encodes M protein) and scpA (which encodes a complement C5a peptidase) was found to b...

  15. 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. PMID:26026835

  16. Complementation analysis of Agrobacterium tumefaciens Ti plasmid virB genes by use of a vir promoter expression vector: virB9, virB10, and virB11 are essential virulence genes.

    OpenAIRE

    J. E. Ward; Dale, E M; Christie, P J; Nester, E W; Binns, A N

    1990-01-01

    The virB gene products of the Agrobacterium tumefaciens tumor-inducing (Ti) plasmid have been proposed to mediate T-DNA transport through the bacterial cell wall into plant cells. Previous genetic analysis of the approximately 9.5-kilobase-pair virB operon has been limited to transposon insertion mutagenesis. Due to the polarity of the transposon insertions, only the last gene in the operon, virB11, is known to provide an essential virulence function. We have now begun to assess the contribut...

  17. Inhibition of Virulence Gene Expression in Staphylococcus aureus by Novel Depsipeptides from a Marine Photobacterium

    DEFF Research Database (Denmark)

    Månsson, Maria; Nielsen, Anita; Kjærulff, Louise;

    2011-01-01

    , the effector molecule of agr. A marine Photobacterium produced compounds interfering with agr in S. aureus strain 8325-4, and bioassay-guided fractionation of crude extracts led to the isolation of two novel cyclodepsipeptides, designated solonamide A and B. Northern blot analysis confirmed the agr interfering...... activity of pure solonamides in both S. aureus strain 8325-4 and the highly virulent, community-acquired strain USA300 (CA-MRSA). To our knowledge, this is the first report of inhibitors of the agr system by a marine bacterium....... sensing system that controls virulence gene expression in Staphylococcus aureus. Using a gene reporter fusion bioassay, we recorded agr interference as enhanced expression of spa, encoding Protein A, concomitantly with reduced expression of hla, encoding α-hemolysin, and rnaIII encoding RNAIII...

  18. Detection of virulence genes in Salmonella Enteritidis isolated from different sources Detecção de genes de virulência in Salmonella Enteritidis isoladas de diferentes fontes

    Directory of Open Access Journals (Sweden)

    Sílvia Dias de Oliveira

    2003-11-01

    Full Text Available The presence of three virulence genes, invA, spvR, and spvC, was determined in Salmonella Enteritidis isolated from poultry, pigs, humans and food. All isolates were positive for the invA gene, with 91.2% being positive for spvR and 90.2% for spvC. There was no significant difference in the prevalence of the virulence genes between isolates from different sources. The results indicate that there is a putative high virulence potential for the S. Enteritidis isolates characterized.A presença de três genes de virulência (invA, spvR e spvC foi determinada em Salmonella Enteritidis isoladas de aves, suínos, humanos e alimentos. Todos os isolados foram positivos para o gene invA, 91,2% também foram positivos para o spvR e 90,2% para o spvC. Não existiu diferença significativa na prevalência dos genes de virulência entre isolados de diferentes origens. Os resultados indicaram que, provavelmente, exista um alto potencial de virulência nos isolados de S. Enteritidis caracterizados.

  19. Within-host evolution decreases virulence in an opportunistic bacterial pathogen

    OpenAIRE

    Mikonranta, Lauri; Mappes, Johanna; Laakso, Jouni; Ketola, Tarmo

    2015-01-01

    Abstract Background Pathogens evolve in a close antagonistic relationship with their hosts. The conventional theory proposes that evolution of virulence is highly dependent on the efficiency of direct host-to-host transmission. Many opportunistic pathogens, however, are not strictly dependent on the hosts due to their ability to reproduce in the free-living environment. Therefore it is likely that conflicting selection pressures for grow...

  20. Rapid Bacterial Identification, Resistance, Virulence and Type Profiling using Selected Reaction Monitoring Mass Spectrometry

    OpenAIRE

    Yannick Charretier; Olivier Dauwalder; Christine Franceschi; Elodie Degout-Charmette; Gilles Zambardi; Tiphaine Cecchini; Chloe Bardet; Xavier Lacoux; Philippe Dufour; Laurent Veron; Hervé Rostaing; Veronique Lanet; Tanguy Fortin; Corinne Beaulieu; Nadine Perrot

    2015-01-01

    Mass spectrometry (MS) in Selected Reaction Monitoring (SRM) mode is proposed for in-depth characterisation of microorganisms in a multiplexed analysis. Within 60–80 minutes, the SRM method performs microbial identification (I), antibiotic-resistance detection (R), virulence assessment (V) and it provides epidemiological typing information (T). This SRM application is illustrated by the analysis of the human pathogen Staphylococcus aureus, demonstrating its promise for rapid characterisation ...

  1. Development of a miniaturized DNA microarray for identification of 66 virulence genes of Legionella pneumophila

    OpenAIRE

    Mariusz Żak; Piotr Zaborowski; Milena Baczewska-Rej; Zasada, Aleksandra A; Renata Matuszewska; Bożena Krogulska

    2011-01-01

    Introduction:For the last five years, Legionella sp. infections and legionnaire’s disease in Poland have been receiving a lot of attention, because of the new regulations concerning microbiological quality of drinking water. This was the inspiration to search for and develop a new assay to identify many virulence genes of Legionella pneumophila to better understand their distribution in environmental and clinical strains. The method might be an invaluable help in infection risk assessment and...

  2. Prevalence of Campylobacter species in milk and milk products, their virulence gene profile and antibiogram

    OpenAIRE

    Shivani Modi; M. N. Brahmbhatt; Y. A. Chatur; J. B. Nayak

    2015-01-01

    Aim: During the last decades, number of food poisoning cases due to Campylobacter occurred, immensely. After poultry, raw milk acts as a second main source of Campylobacter. Therefore, the present study was undertaken to detect the prevalence of Campylobacters in milk and milk products and to know the antibiotic sensitivity and virulence gene profile of Campylobacter spp. in Anand city, Gujarat, India. Materials and Methods: A total of 240 samples (85 buffalo milk, 65 cow milk, 30 cheese, ...

  3. Disruption of the Phospholipase D Gene Attenuates the Virulence of Aspergillus fumigatus

    OpenAIRE

    Li, Xianping; Gao, Meihua; Han, Xuelin; Tao, Sha; Zheng, Dongyu; Cheng, Ying; Yu, Rentao; Han, Gaige; Schmidt, Martina; Han, Li

    2012-01-01

    Aspergillus fumigatus is the most prevalent airborne fungal pathogen that induces serious infections in immunocompromised patients. Phospholipases are key enzymes in pathogenic fungi that cleave host phospholipids, resulting in membrane destabilization and host cell penetration. However, knowledge of the impact of phospholipases on A. fumigatus virulence is rather limited. In this study, disruption of the pld gene encoding phospholipase D (PLD), an important member of the phospholipase protei...

  4. Domains Required for Transcriptional Activation Show Conservation in the Mga Family of Virulence Gene Regulators

    OpenAIRE

    Vahling, Cheryl M.; McIver, Kevin S.

    2006-01-01

    Mga, or the multigene regulator of the group A streptococcus (GAS) (Streptococcus pyogenes), is a transcriptional regulator of virulence genes important for colonization and immune evasion. All serotypes of the GAS possess one of two divergent mga alleles (mga-1 or mga-2), and orthologues of Mga have also been identified in other pathogenic streptococci. To date, the only functional motifs established within Mga are two amino-terminal DNA-binding domains (HTH-3 and HTH-4). To uncover novel do...

  5. The Genetic Diversity of Helicobacter pylori Virulence Genes Is Not Associated with Gastric Atrophy Progression

    OpenAIRE

    Kita, Masahide; Yokota,Kenji; Okada, Hiroyuki; Take,Susumu; Takenaka, Ryuta; Kawahara, Yoshiro; Oguma, Keiji; Matsushita, Osamu; Yamamoto, Kazuhide

    2013-01-01

    Atrophy of the gastric mucosa is a precursor of intestinal-type gastric cancer, and Helicobacter pylori infection causes atrophic gastritis. The aim of this study was to determine whether the genetic diversity of H. pylori virulence genes is associated with the development and progression of gastric atrophy in humans. We isolated and cultured H. pylori strains from patients with gastric ulcer and duodenal ulcer accompanied by atrophic gastritis in background mucosa. H. pylori strains were sto...

  6. Virulence genes and antimicrobial resistance of Pasteurella multocida isolated from poultry and swine

    Science.gov (United States)

    Furian, Thales Quedi; Borges, Karen Apellanis; Laviniki, Vanessa; da Silveira Rocha, Silvio Luis; de Almeida, Camila Neves; do Nascimento, Vladimir Pinheiro; Salle, Carlos Tadeu Pippi; de Souza Moraes, Hamilton Luiz

    2016-01-01

    Pasteurella multocida causes atrophic rhinitis in swine and fowl cholera in birds, and is a secondary agent in respiratory syndromes. Pathogenesis and virulence factors involved are still poorly understood. The aim of this study was to detect 22 virulence-associated genes by PCR, including capsular serogroups A, B and D genes and to evaluate the antimicrobial susceptibility of P. multocida strains from poultry and swine. ompH, oma87, plpB, psl, exbD-tonB, fur, hgbA, nanB, sodA, sodC, ptfA were detected in more than 90% of the strains of both hosts. 91% and 92% of avian and swine strains, respectively, were classified in serogroup A. toxA and hsf-1 showed a significant association to serogroup D; pmHAS and pfhA to serogroup A. Gentamicin and amoxicillin were the most effective drugs with susceptibility higher than 97%; however, 76.79% of poultry strains and 85% of swine strains were resistant to sulphonamides. Furthermore, 19.64% and 36.58% of avian and swine strains, respectively, were multi-resistant. Virulence genes studied were not specific to a host and may be the result of horizontal transmission throughout evolution. High multidrug resistance demonstrates the need for responsible use of antimicrobials in animals intended for human consumption, in addition to antimicrobial susceptibility testing to P. multocida. PMID:26887247

  7. Expression of the Salmonella virulence plasmid gene spvB in cultured macrophages and nonphagocytic cells.

    Science.gov (United States)

    Fierer, J; Eckmann, L; Fang, F; Pfeifer, C; Finlay, B B; Guiney, D

    1993-12-01

    Certain serotypes of salmonellae carry virulence plasmids that greatly enhance the pathogenicity of these bacteria in experimentally infected mice. This phenotype is largely attributable to the 8-kb spv regulon. However, spv genes are not expressed while bacteria grow in vitro. We now show that spvB, which is required for virulence, is expressed rapidly after Salmonella dublin is ingested by cultured J774 and murine peritoneal macrophages and that expression is not affected by the alkalinization of intracellular vesicles. The level of induction of spvB is reduced when macrophages are pretreated with gamma interferon. spvB is also expressed in human and canine epithelial cell lines and a human hepatoma cell line. In all cases, spvB expression is dependent on the spvR gene, just as it is in stationary-phase cultures in vitro. These data suggest that spv virulence genes are expressed by intracellular salmonellae in vivo in response to a signal that is common to the intracellular compartments of cells that are invaded by salmonellae. PMID:8225598

  8. Characterization of Antimicrobial Resistance Patterns and Detection of Virulence Genes in Campylobacter Isolates in Italy

    Directory of Open Access Journals (Sweden)

    Elisabetta Di Giannatale

    2014-02-01

    Full Text Available Campylobacter has developed resistance to several antimicrobial agents over the years, including macrolides, quinolones and fluoroquinolones, becoming a significant public health hazard. A total of 145 strains derived from raw milk, chicken faeces, chicken carcasses, cattle faeces and human faeces collected from various Italian regions, were screened for antimicrobial susceptibility, molecular characterization (SmaI pulsed-field gel electrophoresis and detection of virulence genes (sequencing and DNA microarray analysis. The prevalence of C. jejuni and C. coli was 62.75% and 37.24% respectively. Antimicrobial susceptibility revealed a high level of resistance for ciprofloxacin (62.76%, tetracycline (55.86% and nalidixic acid (55.17%. Genotyping of Campylobacter isolates using PFGE revealed a total of 86 unique SmaI patterns. Virulence gene profiles were determined using a new microbial diagnostic microarray composed of 70-mer oligonucleotide probes targeting genes implicated in Campylobacter pathogenicity. Correspondence between PFGE and microarray clusters was observed. Comparisons of PFGE and virulence profiles reflected the high genetic diversity of the strains examined, leading us to speculate different degrees of pathogenicity inside Campylobacter populations.

  9. Relationship of biofilm formation and different virulence genes in uropathogenic Escherichia coli isolates from Northwest Iran

    Directory of Open Access Journals (Sweden)

    Fattahi, Sargol

    2015-07-01

    Full Text Available Background and objectives: The ( bacterium is one of the main causative agents of urinary tract infections (UTI worldwide. The ability of this bacterium to form biofilms on medical devices such as catheters plays an important role in the development of UTI. The aim of the present study was to investigate the possible relationship between virulence factors and biofilm formation of isolates responsible for urinary tract infection.Materials and methods: A total of 100 isolates isolated from patients with UTI were collected and characterized by routine bacteriological methods. In vitro biofilm formation by these isolates was determined using the 96-well microtiter-plate test, and the presence of , , and virulence genes was examined by PCR assay. Data analysis was performed using SPSS 16.0 software.Results: From 100 isolates isolated from UTIs, 92% were shown to be biofilm positive. The genes , , and were detected in 43%, 94% and 26% of isolates, respectively. Biofilm formation in isolates that expressed , , and genes was 100%, 93%, and 100%, respectively. A significant relationship was found between presence of the gene and biofilm formation in isolates isolated from UTI (<0.01, but there was no statistically significant correlation between presence of and genes with biofilm formation (<0.072, <0.104. Conclusion: Results showed that and genes do not seem to be necessary or sufficient for the production of biofilm in , but the presence of correlates with increased biofilm formation of urinary tract isolates. Overall, the presence of , , and virulence genes coincides with in vitro biofilm formation in uropathogenic

  10. Targeting QseC Signaling and Virulence for Antibiotic Development

    OpenAIRE

    Rasko, David A.; Moreira, Cristiano G.; Li, De Run; Reading, Nicola C.; Ritchie, Jennifer M.; Waldor, Matthew K.; Williams, Noelle; Taussig, Ron; Wei, Shuguang; Roth, Michael; Hughes, David T.; Huntley, Jason F.; Fina, Maggy W.; Falck, John R.; Sperandio, Vanessa

    2008-01-01

    Many bacterial pathogens rely on a conserved membrane histidine sensor kinase, QseC, to respond to host adrenergic signaling molecules and bacterial signals in order to promote the expression of virulence factors. Using a high-throughput screen, we identified a small molecule, LED209, that inhibits the binding of signals to QseC, preventing its autophosphorylation and consequently inhibiting QseC-mediated activation of virulence gene expression. LED209 is not toxic and does not inhibit pathog...

  11. Investigation of potential virulence genes and antibiotic resistance characteristics of Enterococcus faecalis isolates from human milk and colostrum samples

    OpenAIRE

    Toğay, Sine Özmen; TEMİZ, Ayhan; ÇELEBİ, Ayten; AÇIK, Leyla; YALÇIN, Sıddika Songül

    2014-01-01

    Enterococci may improve the typical taste and flavor of fermented foods through their proteolytic and lipolytic activities. However, some enterococcal strains are recognized as nosocomial pathogens, which have virulence genes and resistance to certain antibiotics. Enteroccocci are also found in human milk microflora. The aim of this study was to investigate the potential virulence genes and antibiotic resistance characteristics of Enterococcus faecalis isolates from human milk and colostrum s...

  12. Effect of P39 Gene Deletion in Live Brucella Vaccine Strains on Residual Virulence and Protective Activity in Mice

    OpenAIRE

    Tibor, Anne; Jacques, Isabelle; Guilloteau, Laurence; Verger, Jean-Michel; Grayon, Maggy; Wansard, Valerie; Letesson, Jean-Jacques

    1998-01-01

    The 39-kilodalton protein (P39) has previously been shown to be an immunodominant protein in Brucella infections. P39 gene deletion mutants of vaccine strains Brucella abortus S19 and Brucella melitensis Rev.1 were constructed by gene replacement. This deletion did not significantly modify the residual virulence of both vaccine strains in CD-1 mice. CD-1 mice vaccinated with the parent or mutant strains were protected against a virulent challenge. Mutant vaccine strains devoid of P39 could pr...

  13. Analysis of adherence, biofilm formation and cytotoxicity suggests a greater virulence potential of Gardnerella vaginalis relative to other bacterial-vaginosis-associated anaerobes.

    Science.gov (United States)

    Patterson, Jennifer L; Stull-Lane, Annica; Girerd, Philippe H; Jefferson, Kimberly K

    2010-02-01

    Worldwide, bacterial vaginosis (BV) is the most common vaginal disorder in women of childbearing age. BV is characterized by a dramatic shift in the vaginal microflora, involving a relative decrease in lactobacilli, and a proliferation of anaerobes. In most cases of BV, the predominant bacterial species found is Gardnerella vaginalis. However, pure cultures of G. vaginalis do not always result in BV, and asymptomatic women are sometimes colonized with low numbers of G. vaginalis. Thus, there is controversy about whether G. vaginalis is an opportunistic pathogen and the causative agent of many cases of BV, or whether BV is a polymicrobial condition caused by the collective effects of an altered microbial flora. Recent studies of the biofilm-forming potential and cytotoxic activity of G. vaginalis have renewed interest in the virulence potential of this organism. In an effort to tease apart the aetiology of this disorder, we utilized in vitro assays to compare three virulence properties of G. vaginalis relative to other BV-associated anaerobes. We designed a viable assay to analyse bacterial adherence to vaginal epithelial cells, we compared biofilm-producing capacities, and we assessed cytotoxic activity. Of the BV-associated anaerobes tested, only G. vaginalis demonstrated all three virulence properties combined. This study suggests that G. vaginalis is more virulent than other BV-associated anaerobes, and that many of the bacterial species frequently isolated from BV may be relatively avirulent opportunists that colonize the vagina after G. vaginalis has initiated an infection. PMID:19910411

  14. Identification of the Avian Pasteurella multocida phoP Gene and Evaluation of the Effects of phoP Deletion on Virulence and Immunogenicity.

    Science.gov (United States)

    Xiao, Kangpeng; Liu, Qing; Liu, Xueyan; Hu, Yunlong; Zhao, Xinxin; Kong, Qingke

    2016-01-01

    Pasteurella multocida (P. multocida) is an animal pathogen of worldwide economic significance that causes fowl cholera in poultry and wild birds. Global gene regulators, including PhoP are important in regulating bacterial virulence and are good targets for developing attenuated vaccines against many pathogenic bacteria. However, the biological significance of phoP gene has not been identified in P. multocida. Here, we identified the phoP gene in P. multocida, and we evaluated the roles of phoP in P. multocida by deleting the phoP gene. The P. multocida phoP mutant exhibited similar growth curves and lipopolysaccharide and outer membrane protein profiles but displayed defective polymyxin resistance in vitro compared with the parent strain. Additionally, the phoP deletion resulted in decreased virulence. The LD50 of the ΔphoP mutant was 32- and 154-fold higher than the parent strain via the oral and intranasal routes, respectively. Transcriptome sequencing analysis showed that 161 genes were up-regulated and 173 genes were down-regulated in the absence of the phoP gene. Finally, the immunogenicity and protective efficacy of the ΔphoP mutant were evaluated. Immunized ducks produced significantly higher levels of serum IgY and bile IgA compared to the control ducks, and immunization with the ΔphoP mutant conferred 54.5% protection efficiency against challenge with the virulent P. multocida. This work provides a platform to dissect the function of phoP and develop a new vaccine against P. multocida. PMID:26703595

  15. Identification of the Avian Pasteurella multocida phoP Gene and Evaluation of the Effects of phoP Deletion on Virulence and Immunogenicity

    Directory of Open Access Journals (Sweden)

    Kangpeng Xiao

    2015-12-01

    Full Text Available Pasteurella multocida (P. multocida is an animal pathogen of worldwide economic significance that causes fowl cholera in poultry and wild birds. Global gene regulators, including PhoP are important in regulating bacterial virulence and are good targets for developing attenuated vaccines against many pathogenic bacteria. However, the biological significance of phoP gene has not been identified in P. multocida. Here, we identified the phoP gene in P. multocida, and we evaluated the roles of phoP in P. multocida by deleting the phoP gene. The P. multocida phoP mutant exhibited similar growth curves and lipopolysaccharide and outer membrane protein profiles but displayed defective polymyxin resistance in vitro compared with the parent strain. Additionally, the phoP deletion resulted in decreased virulence. The LD50 of the ΔphoP mutant was 32- and 154-fold higher than the parent strain via the oral and intranasal routes, respectively. Transcriptome sequencing analysis showed that 161 genes were up-regulated and 173 genes were down-regulated in the absence of the phoP gene. Finally, the immunogenicity and protective efficacy of the ΔphoP mutant were evaluated. Immunized ducks produced significantly higher levels of serum IgY and bile IgA compared to the control ducks, and immunization with the ΔphoP mutant conferred 54.5% protection efficiency against challenge with the virulent P. multocida. This work provides a platform to dissect the function of phoP and develop a new vaccine against P. multocida.

  16. Identification of genes preferentially expressed by highly virulent piscine Streptococcus agalactiae upon interaction with macrophages.

    Directory of Open Access Journals (Sweden)

    Chang-Ming Guo

    Full Text Available Streptococcus agalactiae, long recognized as a mammalian pathogen, is an emerging concern with regard to fish. In this study, we used a mouse model and in vitro cell infection to evaluate the pathogenetic characteristics of S. agalactiae GD201008-001, isolated from tilapia in China. This bacterium was found to be highly virulent and capable of inducing brain damage by migrating into the brain by crossing the blood-brain barrier (BBB. The phagocytosis assays indicated that this bacterium could be internalized by murine macrophages and survive intracellularly for more than 24 h, inducing injury to macrophages. Further, selective capture of transcribed sequences (SCOTS was used to investigate microbial gene expression associated with intracellular survival. This positive cDNA selection technique identified 60 distinct genes that could be characterized into 6 functional categories. More than 50% of the differentially expressed genes were involved in metabolic adaptation. Some genes have previously been described as associated with virulence in other bacteria, and four showed no significant similarities to any other previously described genes. This study constitutes the first step in further gene expression analyses that will lead to a better understanding of the molecular mechanisms used by S. agalactiae to survive in macrophages and to cross the BBB.

  17. Cloning of a very virulent plus, 686 strain of Marek’s disease virus as a bacterial artificial chromosome

    Science.gov (United States)

    Bacterial artificial chromosome (BAC) vectors were first developed to facilitate propagation and manipulation of large DNA fragments. This technology was later used to clone full-length genomes of large DNA viruses to study viral gene function. Marek’s disease virus (MDV) is a highly oncogenic herpe...

  18. Variant surface antigens, virulence genes and the pathogenesis of malaria

    DEFF Research Database (Denmark)

    Deitsch, Kirk W; Hviid, Lars

    2004-01-01

    The first Molecular Approaches to Malaria meeting was held 2-5 February 2000 in Lorne, Australia. Following the meeting, Brian Cooke, Mats Wahlgren and Ross Coppel predicted that research into the molecular details of the mechanisms behind sequestration of parasitized erythrocytes would "become...... increasingly more complicated, with further interactions, receptors, ligands and functional domains". Furthermore, they cautioned that "the challenge will be not to lose ourselves in the molecular detail, but remain focused on the role of [the var genes and other multigene families] in pathogenesis of malaria......". We contemplate on these statements, following the recent second Molecular Approaches to Malaria meeting, which was held at the same venue on 2-5 February 2004....

  19. mADP-RTs: Versatile virulence factors from bacterial pathogens of plants and mammals

    OpenAIRE

    Lennart eWirthmueller; Banfield, Mark J.

    2012-01-01

    Mono ADP-ribosyltransferases (mADP-RTs) are a family of enzymes that cleave NAD+ and covalently attach the ADP-ribosyl moiety to target proteins. mADP-RTs are well established as important virulence factors of bacteria that infect mammals. Cholera toxin, pertussis toxin and diphteria toxin are three of the best-known examples of mADP-RTs. They modify host target proteins in order to promote infection and/or killing of the host cell. Despite low sequence similarity at the primary amino acid le...

  20. COMPARATIVE TRANSCRIPT PROFILING OF Candida albicans AND Candida dubliniensis IDENTIFIES SFL2, A C. albicans GENE REQUIRED FOR VIRULENCE IN A RECONSTITUTED EPITHELIAL INFECTION MODEL

    OpenAIRE

    HIGGINS, JUDY; Sullivan, Derek; Coleman, David; Moran, Gary

    2010-01-01

    Candida albicans and Candida dubliniensis are closely related species displaying differences in virulence and genome content, therefore providing potential opportunities to identify novel C. albicans virulence genes. C. albicans gene arrays were used for comparative analysis of global gene expression in the two species in reconstituted human oral epithelium (RHE). C. albicans (SC5314) showed upregulation of hypha-specific and virulence genes within 30 min postinoculation, coinciding with rapi...

  1. Effects of volatile organic compounds produced by Bacillus amyloliquefaciens on the growth and virulence traits of tomato bacterial wilt pathogen Ralstonia solanacearum.

    Science.gov (United States)

    Raza, Waseem; Wang, Jichen; Wu, Yuncheng; Ling, Ning; Wei, Zhong; Huang, Qiwei; Shen, Qirong

    2016-09-01

    The production of volatile organic compounds (VOCs) by microbes is an important characteristic for their selection as biocontrol agents against plant pathogens. In this study, we identified the VOCs produced by the biocontrol strain Bacillus amyloliquefaciens T-5 and evaluated their impact on the growth and virulence traits of tomato bacterial wilt pathogen Ralstonia solanacearum. The results showed that the VOCs of strain T-5 significantly inhibited the growth of R. solanacearum in agar medium and in soil. In addition, VOCs significantly inhibited the motility traits, root colonization, biofilm formation, and production of antioxidant enzymes and exopolysaccharides by R. solanacearum. However, no effect of VOCs on the production of hydrolytic enzymes by R. solanacearum was observed. The strain T-5 produced VOCs, including benzenes, ketones, aldehydes, alkanes, acids, and one furan and naphthalene compound; among those, 13 VOCs showed 1-10 % antibacterial activity against R. solanacearum in their produced amounts by T-5; however, the consortium of all VOCs produced on agar medium, in sterilized soil, and in natural soil showed 75, 62, and 85 % growth inhibition of R. solanacearum, respectively. The real-time PCR analysis further confirmed the results when the expression of different virulence- and metabolism-related genes in R. solanacearum cells was decreased after exposure to the VOCs of strain T-5. The results of this study clearly revealed the significance of VOCs in the control of plant pathogens. This information would help to better comprehend the microbial interactions mediated by VOCs in nature and to develop safer strategies to control plant disease. PMID:27183998

  2. Evaluation of the gene encoding the enzyme βHPMEH for the bacterial wilt inhibition caused by Ralstonia solanacearum

    Directory of Open Access Journals (Sweden)

    Elizabeth Fernandez

    2015-10-01

    Full Text Available Ralstonia solanacearum is the causal agent of the devastating bacterial wilt disease that attacks important agricultural crops such as potato, tomato, banana, among others, causing serious yield losses. Control of R. solanacearum is difficult because of its wide range of alternate hosts, its long survival in soil, its biological and genetic variation, the lack of natural resistance sources and the insufficiency of the appropriate chemical control measures. Quorum sensing is the term that describes the phenomenon whereby the accumulation of molecules allows bacteria to know the number of bacteria found in the environment (population density. R. solanacearum has a quorum sensing system for the regulation of the expression of virulence genes; the molecule 3-OH-PAME is the self-regulatory signal. The molecule ΒHPMEH hydrolyzes 3-OH-PAME nullifying the signal of virulence, and thus, the quorum sensing communication in R. solanacearum. In order to evaluate the βhpmeh gene we designed two vectors that express this gene under the control of two different promoters. Both vectors were verified by restriction analysis and sequencing. Agroinfiltration assays were used to analyze gene expression and the effect against R. solanacearum in potato (Solanum tuberosum leaves. The results of the transient expression experiments showed that the expression of gene βhpmeh caused a delay in the appearance of symptoms of bacterial wilt and thus is a good candidate for whole genetic plant transformation.

  3. Porcine E. coli: virulence-associated genes, resistance genes and adhesion and probiotic activity tested by a new screening method.

    Directory of Open Access Journals (Sweden)

    Peter Schierack

    Full Text Available We established an automated screening method to characterize adhesion of Escherichia coli to intestinal porcine epithelial cells (IPEC-J2 and their probiotic activity against infection by enteropathogenic E. coli (EPEC. 104 intestinal E. coli isolates from domestic pigs were tested by PCR for the occurrence of virulence-associated genes, genes coding for resistances to antimicrobial agents and metals, and for phylogenetic origin by PCR. Adhesion rates and probiotic activity were examined for correlation with the presence of these genes. Finally, data were compared with those from 93 E. coli isolates from wild boars. Isolates from domestic pigs carried a broad variety of all tested genes and showed great diversity in gene patterns. Adhesions varied with a maximum of 18.3 or 24.2 mean bacteria adherence per epithelial cell after 2 or 6 hours respectively. Most isolates from domestic pigs and wild boars showed low adherence, with no correlation between adhesion/probiotic activity and E. coli genes or gene clusters. The gene sfa/foc, encoding for a subunit of F1C fimbriae did show a positive correlative association with adherence and probiotic activity; however E. coli isolates from wild boars with the sfa/foc gene showed less adhesion and probiotic activity than E. coli with the sfa/foc gene isolated from domestic pigs after 6 hour incubation. In conclusion, screening porcine E. coli for virulence associated genes genes, adhesion to intestinal epithelial cells, and probiotic activity revealed a single important adhesion factor, several probiotic candidates, and showed important differences between E. coli of domestic pigs and wild boars.

  4. Parallel bacterial evolution within multiple patients identifies candidate pathogenicity genes

    OpenAIRE

    Lieberman, Tami D; Michel, Jean-Baptiste; Aingaran, Mythili; Potter-Bynoe, Gail; Roux, Damien; Davis, Michael R.; Skurnik, David; Leiby, Nicholas; LiPuma, John J.; Goldberg, Joanna B.; McAdam, Alexander J.; Priebe, Gregory P.; Kishony, Roy

    2011-01-01

    Bacterial pathogens evolve during the infection of their human hosts 1-8 , but separating adaptive and neutral mutations remains challenging 9-11 . Here, we identify bacterial genes under adaptive evolution by tracking recurrent patterns of mutations in the same pathogenic strain during the infection of multiple patients. We conducted a retrospective study of a Burkholderia dolosa outbreak among people with cystic fibrosis, sequencing the genomes of 112 isolates collected from 14 individuals ...

  5. Efficient Gene Transfer in Bacterial Cell Chains

    OpenAIRE

    Babic, Ana; Berkmen, Melanie B.; Lee, Catherine A.; Grossman, Alan D.

    2011-01-01

    Horizontal gene transfer contributes to evolution and the acquisition of new traits. In bacteria, horizontal gene transfer is often mediated by conjugative genetic elements that transfer directly from cell to cell. Integrative and conjugative elements (ICEs; also known as conjugative transposons) are mobile genetic elements that reside within a host genome but can excise to form a circle and transfer by conjugation to recipient cells. ICEs contribute to the spread of genes involved in pathoge...

  6. Enhanced Virulence Gene Activity of Agrobacterium in Muskmelon (Cucumis melo L. cv. ‘Birdie’

    Directory of Open Access Journals (Sweden)

    Abul K.M. MOHIUDDIN

    2011-05-01

    Full Text Available Muskmelon (Cucumis melo L. cultivar ‘Birdie’, was evaluated for its response to the tumorigenic Agrobacterium tumefaciens and the oncogenic A. rhizogenes strains. Stem and petiole of three week-old in vitro-grown muskmelon plants were inoculated with five strains of A. tumefaciens and A. rhizogenes each and observed phenotypic expressions i.e. induction of crown galls and hairy roots. This phenotypic expression was efficaciously increased when virulence gene activity of different strains of two Agrobacterium species was enhanced. Intensive studies on enhancement of virulence gene activity of Agrobacterium found to be correlated to the appropriate light intensity (39.3 μmol m-2 s-1 with a specific concentration of monocyclic phenolic compound, acetosyringone (20 μM. The gene activity was also influenced by several other physical factors e.g. plant tissue type, Agrobacterium species and their strains, and plant tissue-Agrobacterium interaction. Among the different A. tumefaciens strains, LBA4404 showed the best virulence gene activity in both stem and petiole through the formation of higher rate of crown galls. On the other hand, strain 15834 of A. rhizogenes showed better gene activity in stem and 8196 in petiole through the formation of higher rate of hairy roots as well as higher average number of hairy roots. Among the two different types of explants, petiole was more susceptible to both Agrobacterium species. Thus it was concluded that future muskmelon transformation study can efficiently be carried out with LBA4404, 15834 and 8196 strains using petiole explants by adding 20 μM of acetosyringone in the medium.

  7. Plasmid fingerprinting and virulence gene detection among indigenous strains of salmonella enterica serovar enteritidis

    International Nuclear Information System (INIS)

    Salmonella enterica serovar Enteritidis is an important frequently reported zoonotic pathogen and a common cause of human gastroenteritis worldwide. The highly conserved Serospecific plasmids (SSPs) and Salmonella plasmid virulence (Spv) genes have been shown to mediate extra-intestinal colonization and systemic infection. The objective of current study was to document the presence of SSPs and SpvB/SpvC genes prevailing in the indigenous population of serovar Enteritidis. A total of 48 epidemiologically unrelated strains of Salmonella enteritidis were included in the study. Preparation of plasmids DNA suitable for endonuclease digestion and separation of respective fragments by agarose gel electrophoresis followed previously described protocols. The plasmids of Escherichia coli V517, 1-kbp ladder, and lambda DNA HindIII fragments served as DNA size standards. Transfer of DNA fragments from agarose gels to nitrocellulose membranes was achieved by capillary blot procedure. An ECL labeled 3.6 kbp HindIII fragment of plasmid PRQ 51 was used as probe for SpvB/SpvC gene detection. Plasmid DNA fingerprinting revealed the presence of two different profiles of approximately 55 kbp and 90 kbp and were identified as virulence plasmids by DNA hybridization. The SpvB/SpvC genes were located on HindIII fragments of 3.6 kbp in each of the two types of virulence plasmids. The study confirms the presence of SSPs and SpvB/SpvC genes in indigenous strains of S. enteritidis isolated from Northern Punjab area of Pakistan and substantiate the previous data on such findings from other parts of the world. (author)

  8. Detection of multiple virulence-associated genes in Listeria monocytogenes isolated from bovine mastitis cases.

    Science.gov (United States)

    Rawool, D B; Malik, S V S; Shakuntala, I; Sahare, A M; Barbuddhe, S B

    2007-01-25

    Clinical samples (n=725) were collected from bovines (n=243) which were positive for mastitis using the California mastitis test (CMT) and somatic cell count (SCC). The clinical samples comprising blood (n=239), milk (n=243), and faecal swabs (n=243) were examined for the presence of pathogenic Listeria spp. Isolation of the pathogen was done using selective enrichment in University of Vermont Medium and plating onto Dominguez-Rodriguez isolation agar. Confirmation of the isolates was based on biochemical tests and Christie, Atkins, Munch-Petersen (CAMP) test followed by pathogenicity testing. Pathogenicity of the isolates was tested by phosphatidylinositol-specific phospholipase C (PI-PLC) assay as well as in vivo tests namely, chick embryo and mice inoculation tests. The isolates were subjected to PCR assay for five virulence-associated genes, plcA, prfA, hlyA, actA and iap. Listeria spp. were isolated from 12 (1.66%) samples. Of these 4 (0.55%) and 1 (0.14%) were confirmed as Listeria monocytogenes and Listeria ivanovii, respectively. L. monocytogenes and L. ivanovii were recovered from milk samples (2) and faecal (3) of mastitic cattle (3) and buffaloes (2). L. monocytogenes recovered from the milk of mastitic cattle and L. ivanovii from the faecal swab of buffalo turned out to be pathogenic. However, the remaining three hemolytic isolates exhibiting positive CAMP test turned out to be negative in PI-PLC assay, chick embryo and mice inoculation. L. monocytogenes and L. ivanovii isolates characterized as pathogenic by PI-PLC assay and in vivo pathogenicity tests were found to possess all the five virulence-associated genes and three genes, plcA, prfA and actA respectively. The remaining three hemolytic but non-pathogenic L. monocytogenes isolates were negative for plcA by PCR. It seems that the plcA gene and its expression (in the PI-PLC assay) have an important role as virulence determinants in pathogenic Listeria spp. In conclusion, the PI-PLC assay and

  9. Deletion of Invasion Protein B in Salmonella enterica Serovar Typhimurium Influences Bacterial Invasion and Virulence.

    Science.gov (United States)

    Chen, Songbiao; Zhang, Chunjie; Liao, Chengshui; Li, Jing; Yu, Chuan; Cheng, Xiangchao; Yu, Zuhua; Zhang, Mingliang; Wang, Yang

    2015-12-01

    Salmonella enterica serovar Typhimurium (S. Typhimurium) has a wide host range and causes infections ranging from severe gastroenteritis to systemic infections in human, as well as causing typhoid-like disease in murine models of infection. S. Typhimurium translocates its effector proteins through the Salmonella pathogenicity island-I (SPI-I)-encoded T3SS-I needle complex. This study focuses on invasion protein B (SipB) of S. Typhimurium, which plays an active role in SPI-I invasion efficiency. To test our hypothesis, a sipB deletion mutant was constructed through double-crossover allelic using the suicide vector pRE112ΔsipB, and its biological characteristics were analyzed. The results showed that the SipB does not affect the growth of Salmonella, but the adherence, invasion, and virulence of the mutant were significantly decreased compared with wild-type S. Typhimurium (SL1344). This research indicates that SipB is an important virulence factor in the pathogenicity of S. Typhimurium. PMID:26341924

  10. Detection and characterization of virulence genes and integrons in Aeromonas veronii isolated from catfish.

    Science.gov (United States)

    Nawaz, Mohamed; Khan, Saeed A; Khan, Ashraf A; Sung, Kidon; Tran, Quynhtien; Kerdahi, Khalil; Steele, Roger

    2010-05-01

    The presence of virulence genes and integrons was determined in 81 strains of Aeromonas veronii isolated from farm-raised catfish. Polymerase chain reaction (PCR) protocols were used to determine the presence of genes for cytotoxic enterotoxin (act), aerolysin (aerA), two cytotonic enterotoxins (ast, alt), lipase (lip), glycerophospholipid:cholesterol acyltransferase (gcaT), serine protease (ser), DNases (exu), elastase (ahyB) and the structural gene flagellin (fla) in the template DNA. Oligonucleotide primers amplified a 231-bp region of the act gene from the template DNA of 97.0% of the isolates. Primers specific for the amplification of the aerA gene amplified a 431-bp region of the aerA gene from the template DNA of 96.0% of the isolates. None of the isolates contained ast or alt genes. Oligonucleotide primers specific for the amplification of lip, gcaT, ser and fla genes, amplified their respective amplicons from 85.0, 78.0, 82.0 and 80.0% of the isolates. None of the isolates contained exu or the elastase genes. Several of the isolates (48.0%) contained class I integrons that confer resistance to multiple antibiotics; various sizes between 0.6 and 3.1 kb were found. None of the isolates contained Class II integrons. Our results indicate that farm-raised catfish may be a source of pathogenic A. veronii and that the potential health risks posed by virulent strains of A. veronii should not be underestimated. PMID:20227596

  11. The role of the st313-td gene in virulence of Salmonella Typhimurium ST313.

    Directory of Open Access Journals (Sweden)

    Ana Herrero-Fresno

    Full Text Available Multidrug-resistant Salmonella enterica serovar Typhimurium ST313 has emerged in sub-Saharan Africa causing severe infections in humans. Therefore, it has been speculated that this specific sequence type, ST313, carries factors associated with increased pathogenicity. We assessed the role in virulence of a gene with a yet unknown function, st313-td, detected in ST313 through comparative genomics. Additionally, the structure of the genomic island ST313-GI, harbouring the gene was determined. The gene st313-td was cloned into wild type S. Typhimurium 4/74 (4/74-C as well as knocked out in S. Typhimurium ST313 02-03/002 (Δst313-td followed by complementation (02-03/002-C. Δst313-td was less virulent in mice following i.p. challenge than the wild type and this phenotype could be partly complemented in trans, indicating that st313-td plays a role during systemic infection. The gene st313-td was shown not to affect invasion of cultured epithelial cells, while the absence of the gene significantly affects uptake and intracellular survival within macrophages. The gene st313-td was proven to be strongly associated to invasiveness, harboured by 92.5% of S. Typhimurium blood isolates (n = 82 and 100% of S. Dublin strains (n = 50 analysed. On the contrary, S. Typhimurium isolates of animal and food origin (n = 82 did not carry st313-td. Six human, non-blood isolates of S. Typhimurium from Belarus, China and Nepal harboured the gene and belonged to sequence types ST398 and ST19. Our data showed a global presence of the st313-td gene and in other sequence types than ST313. The gene st313-td was shown to be expressed during logarithmic phase of growth in 14 selected Salmonella strains carrying the gene. This study reveals that st313-td plays a role in S. Typhimurium ST313 pathogenesis and adds another chapter to understanding of the virulence of S. Typhimurium and in particular of the emerging sequence type ST313.

  12. The role of the st313-td gene in virulence of Salmonella Typhimurium ST313.

    Science.gov (United States)

    Herrero-Fresno, Ana; Wallrodt, Inke; Leekitcharoenphon, Pimlapas; Olsen, John Elmerdahl; Aarestrup, Frank M; Hendriksen, Rene S

    2014-01-01

    Multidrug-resistant Salmonella enterica serovar Typhimurium ST313 has emerged in sub-Saharan Africa causing severe infections in humans. Therefore, it has been speculated that this specific sequence type, ST313, carries factors associated with increased pathogenicity. We assessed the role in virulence of a gene with a yet unknown function, st313-td, detected in ST313 through comparative genomics. Additionally, the structure of the genomic island ST313-GI, harbouring the gene was determined. The gene st313-td was cloned into wild type S. Typhimurium 4/74 (4/74-C) as well as knocked out in S. Typhimurium ST313 02-03/002 (Δst313-td) followed by complementation (02-03/002-C). Δst313-td was less virulent in mice following i.p. challenge than the wild type and this phenotype could be partly complemented in trans, indicating that st313-td plays a role during systemic infection. The gene st313-td was shown not to affect invasion of cultured epithelial cells, while the absence of the gene significantly affects uptake and intracellular survival within macrophages. The gene st313-td was proven to be strongly associated to invasiveness, harboured by 92.5% of S. Typhimurium blood isolates (n = 82) and 100% of S. Dublin strains (n = 50) analysed. On the contrary, S. Typhimurium isolates of animal and food origin (n = 82) did not carry st313-td. Six human, non-blood isolates of S. Typhimurium from Belarus, China and Nepal harboured the gene and belonged to sequence types ST398 and ST19. Our data showed a global presence of the st313-td gene and in other sequence types than ST313. The gene st313-td was shown to be expressed during logarithmic phase of growth in 14 selected Salmonella strains carrying the gene. This study reveals that st313-td plays a role in S. Typhimurium ST313 pathogenesis and adds another chapter to understanding of the virulence of S. Typhimurium and in particular of the emerging sequence type ST313. PMID:24404174

  13. CovS simultaneously activates and inhibits the CovR-mediated repression of distinct subsets of group A Streptococcus virulence factor-encoding genes.

    Science.gov (United States)

    Treviño, Jeanette; Perez, Nataly; Ramirez-Peña, Esmeralda; Liu, Zhuyun; Shelburne, Samuel A; Musser, James M; Sumby, Paul

    2009-08-01

    To colonize and cause disease at distinct anatomical sites, bacterial pathogens must tailor gene expression in a microenvironment-specific manner. The molecular mechanisms that control the ability of the human bacterial pathogen group A Streptococcus (GAS) to transition between infection sites have yet to be fully elucidated. A key regulator of GAS virulence gene expression is the CovR-CovS two-component regulatory system (also known as CsrR-CsrS). covR and covS mutant strains arise spontaneously during invasive infections and, in in vivo models of infection, rapidly become dominant. Here, we compared wild-type GAS with covR, covS, and covRS isogenic mutant strains to investigate the heterogeneity in the types of natural mutations that occur in covR and covS and the phenotypic consequences of covR or covS mutation. We found that the response regulator CovR retains some regulatory function in the absence of CovS and that CovS modulates CovR to significantly enhance repression of one group of genes (e.g., the speA, hasA, and ska genes) while it reduces repression of a second group of genes (e.g., the speB, grab, and spd3 genes). We also found that different in vivo-induced covR mutations can lead to strikingly different transcriptomes. While covS mutant strains show increased virulence in several invasive models of infection, we determined that these mutants are significantly outcompeted by wild-type GAS during growth in human saliva, an ex vivo model of upper respiratory tract infection. We propose that CovS-mediated regulation of CovR activity plays an important role in the ability of GAS to cycle between pharyngeal and invasive infections. PMID:19451242

  14. Antibiotic exposure can induce various bacterial virulence phenotypes in multidrug-resistant Salmonella enterica serovar Typhimurium

    Science.gov (United States)

    Salmonella is one of the most prevalent bacterial foodborne diseases in the United States and causes an estimated 1 million human cases every year. Multidrug-resistant (MDR) Salmonella has emerged as a public health issue as it has been associated with increased morbidity in humans and mortality in...

  15. Stress, Sublethal Injury, Resuscitation and Virulence of Bacterial Foodborne Pathogens: A Review

    Science.gov (United States)

    Environmental stress and food preservation methods (e.g., heating, chilling, acidity, and alkalinity) are known to induce adaptive responses within the bacterial cell. Microorganisms that survive a given stress often gain resistance to that stress or other stresses via cross-protection. The physio...

  16. Virulence genes, antibiotic resistance and integrons in Escherichia coli strains isolated from synanthropic birds from Spain.

    Science.gov (United States)

    Sacristán, C; Esperón, F; Herrera-León, S; Iglesias, I; Neves, E; Nogal, V; Muñoz, M J; de la Torre, A

    2014-01-01

    The aim of this study was to determine the presence of virulence genes and antibiotic resistance profiles in 164 Escherichia coli strains isolated from birds (feral pigeons, hybrid ducks, house sparrows and spotless starlings) inhabiting urban and rural environments. A total of eight atypical enteropathogenic E. coli strains were identified: one in a house sparrow, four in feral pigeons and three in spotless starlings. Antibiotic resistance was present in 32.9% (54) of E. coli strains. The dominant type of resistance was to tetracycline (21.3%), ampicillin (19.5%) and sulfamethoxazole (18.9%). Five isolates had class 1 integrons containing gene cassettes encoding for dihydrofolate reductase A (dfrA) and aminoglycoside adenyltransferase A (aadA), one in a feral pigeon and four in spotless starlings. To our knowledge, the present study constitutes the first detection of virulence genes from E. coli in spotless starlings and house sparrows, and is also the first identification worldwide of integrons containing antibiotic resistance gene cassettes in E. coli strains from spotless starlings and pigeons. PMID:24689431

  17. Complementation analysis of Agrobacterium tumefaciens Ti plasmid virB genes by use of a vir promoter expression vector: virB9, virB10, and virB11 are essential virulence genes.

    Science.gov (United States)

    Ward, J E; Dale, E M; Christie, P J; Nester, E W; Binns, A N

    1990-09-01

    The virB gene products of the Agrobacterium tumefaciens tumor-inducing (Ti) plasmid have been proposed to mediate T-DNA transport through the bacterial cell wall into plant cells. Previous genetic analysis of the approximately 9.5-kilobase-pair virB operon has been limited to transposon insertion mutagenesis. Due to the polarity of the transposon insertions, only the last gene in the operon, virB11, is known to provide an essential virulence function. We have now begun to assess the contribution of the other virB genes to virulence. First, several previously isolated Tn3-HoHo1 insertions in the 3' end of the virB operon were precisely mapped by nucleotide sequence analysis. Protein extracts from A. tumefaciens strains harboring these insertions on the Ti plasmid were subjected to immunostaining analysis with VirB4-, VirB10-, and VirB11-specific antisera to determine the effect of the insertion on virB gene expression. In this manner, avirulent mutants containing polar insertions in the virB9 and virB10 genes were identified. To carry out a complementation analysis with these virB mutants, expression vectors were constructed that allow cloned genes to be expressed from the virB promoter in A. tumefaciens. These plasmids were used to express combinations of the virB9, virB10, and virB11 genes in trans in the virB insertion mutants, thereby creating strains lacking only one of these three virB gene products. Virulence assays on Kalanchoe daigremontiana demonstrated that in addition to virB11, the virB9 and virB10 genes are required for tumorigenicity. PMID:2203743

  18. Characterization of the wzc gene from Pantoea sp. strain PPE7 and its influence on extracellular polysaccharide production and virulence on Pleurotus eryngii.

    Science.gov (United States)

    Kim, Min Keun; Lee, Young Han; Kim, Hyeran; Lee, Jeongyeo; Ryu, Jae San

    2015-01-01

    To characterize of the pathogenicity gene from the soft rot pathogen Pantoea sp. PPE7 in Pleurotus eryngii, we constructed over 10,000 kanamycin-resistant transposon mutants of Pantoea sp. strain PPE7 by transposon mutagenesis. One mutant, Pantoea sp. NPPE9535, did not cause a soft rot disease on Pleurotus eryngii was confirmed by the pathogenicity test. The transposon was inserted into the wzc gene and the disruption of the wzc gene resulted in the reduction of polysaccharide production and abolished the virulence of Pantoea sp. strain PPE7 in P. eryngii. Analysis of the hydropathic profile of this protein indicated that it is composed of two main domains: an N-terminal domain including two transmembrane α-helices and a C-terminal cytoplasmic domain consisting of a tyrosine-rich region. Comparative analysis indicated that the amino acid sequence of Wzc is similar to that of a number of proteins involved in the synthesis or export of polysaccharides in other bacterial species. Purified GST-Wzc was found to affect the phosphorylation of tyrosine residue in vivo. These results showed that the wzc gene might play an important role in the virulence of Pantoea sp. strain PPE7 in P. eryngii. PMID:25183654

  19. Salmonella Modulates Metabolism During Growth under Conditions that Induce Expression of Virulence Genes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young-Mo; Schmidt, Brian; Kidwai, Afshan S.; Jones, Marcus B.; Deatherage, Brooke L.; Brewer, Heather M.; Mitchell, Hugh D.; Palsson, Bernhard O.; McDermott, Jason E.; Heffron, Fred; Smith, Richard D.; Peterson, Scott N.; Ansong, Charles; Hyduke, Daniel R.; Metz, Thomas O.; Adkins, Joshua N.

    2013-04-05

    Salmonella enterica serovar Typhimurium (S. Typhimurium) is a facultative pathogen that uses complex mechanisms to invade and proliferate within mammalian host cells. To investigate possible contributions of metabolic processes in S. Typhimurium grown under conditions known to induce expression of virulence genes, we used a metabolomics-driven systems biology approach coupled with genome scale modeling. First, we identified distinct metabolite profiles associated with bacteria grown in either rich or virulence-inducing media and report the most comprehensive coverage of the S. Typhimurium metabolome to date. Second, we applied an omics-informed genome scale modeling analysis of the functional consequences of adaptive alterations in S. Typhimurium metabolism during growth under our conditions. Excitingly, we observed possible sequestration of metabolites recently suggested to have immune modulating roles. Modeling efforts highlighted a decreased cellular capability to both produce and utilize intracellular amino acids during stationary phase culture in virulence conditions, despite significant abundance increases for these molecules as observed by our metabolomics measurements. Model-guided analysis suggested that alterations in metabolism prioritized other activities necessary for pathogenesis instead, such as lipopolysaccharide biosynthesis.

  20. Occurrence of spvA Virulence Gene and Clinical Significance for Multidrug-Resistant Salmonella Strains ▿

    OpenAIRE

    Gebreyes, Wondwossen A.; Thakur, Siddhartha; Dorr, Paul; Tadesse, Daniel A.; Post, Karen; Wolf, Leslie

    2008-01-01

    Nontyphoidal Salmonella strains are important reservoirs of antimicrobial resistance. An important issue that has not been investigated is whether the multiresistant Salmonella strains are more virulent than their susceptible counterparts. Salmonella isolates collected from clinical human (n = 888) and porcine (n = 2,120) cases at the same time period and geographic location were investigated. Antimicrobial susceptibility, PCR analysis for the spvA virulence gene, and pulsed-field gel electro...

  1. Global Regulation of Virulence Determinants During Plant Colonization in the Bacterial Phytopathogen, Pantoea stewartii subsp. stewartii

    OpenAIRE

    Burbank, Lindsey

    2014-01-01

    Pantoea stewartii subsp. stewartii, the etiological agent of Stewart's wilt, is a bacterial pathogen of sweet corn which colonizes both the apoplast and xylem tissues. During the initial stages of the infection process, the pathogen forms water-soaked lesions through lysis of the plant cells, followed by colonization of the xylem tissue where it can grow to high cell densities and form biofilms. Biofilm formation within the xylem vessels can block water flow, causing the characteristic wiltin...

  2. Functional analysis of virulence potential from Gardnerella vaginalis and other anaerobes commonly associated with Bacterial vaginosis

    OpenAIRE

    Castro, J.; Machado, António; Alves, P.; Sousa, Cármen; Cereija, Tatiana Barros Reis; França, Ângela; Jefferson, Kimberly K; Cerca, Nuno

    2013-01-01

    In the past half century, bacterial vaginosis (BV) has been a controversial topic in medical microbiology, and despite the wealth of information on this topic, the etiological agent has not yet been definitively identified [1]. The first advances on BV pointed Gardnerella vaginalis as the infectious causative agent of BV [2] but soon after it was found that G. vaginalis was also present in healthy women [3]. Additionally, G. vaginalis was not able to cause BV consistently. Furthermore, other ...

  3. Anaerobes and Bacterial Vaginosis in Pregnancy: Virulence Factors Contributing to Vaginal Colonisation

    OpenAIRE

    Africa, Charlene W.J.; Janske Nel; Megan Stemmet

    2014-01-01

    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 poss...

  4. Molecular pathogenesis of Helicobacter pylori infection: the role of bacterial virulence factors.

    Science.gov (United States)

    Molnar, Bela; Galamb, Orsolya; Sipos, Ferenc; Leiszter, Katalin; Tulassay, Zsolt

    2010-01-01

    Helicobacter pylori is one of the most common pathogens affecting humankind, infecting approximately 50% of the world's population. Of those infected, many will develop asymptomatic gastritis, but 10% develop gastric or duodenal ulcers. The clinical outcome of the infection may involve a combination of bacterial factors, host factors and environmental factors. In the process of development of gastritis, ulceration and cancer, several cellular and molecular steps follow each other. Infection, acid survival, adhesion, cytotoxicity, epithelial cell turnover changes, inflammation, regeneration or pathological alteration towards erosions, ulceration, and cancer can be observed on the cellular level. Bacterial factors like urease, AmiE, AmiF, hydrogenase and arginase are needed for survival in the acidic gastric environment. The bacterial flagellae are essential to move the bacteria towards the epithelial surface. Adhesive factors like BabA, SabA and ureaseA are necessary for adhesion against MHC-II complexes and Le antigens. The bacteria VacA and CagA are cytotoxic factors. The Cag type IV secretion system delivers these proteins inside the epithelial cells. After disruption of epithelial cell junctions, the bacteria can pass through the gastric wall facing direct immune response from neutrophils, lymphocytes, mast cells and dendritic cells. This review describes and summarizes our present molecular biological information and knowledge about the Helicobacter infective component, cell functions and processes. The possible role of host counter responses and interactions with gastric epithelia and immune cells are also detailed. PMID:21088410

  5. Changes in rhizosphere bacterial gene expression following glyphosate treatment.

    Science.gov (United States)

    Newman, Molli M; Lorenz, Nicola; Hoilett, Nigel; Lee, Nathan R; Dick, Richard P; Liles, Mark R; Ramsier, Cliff; Kloepper, Joseph W

    2016-05-15

    In commercial agriculture, populations and interactions of rhizosphere microflora are potentially affected by the use of specific agrichemicals, possibly by affecting gene expression in these organisms. To investigate this, we examined changes in bacterial gene expression within the rhizosphere of glyphosate-tolerant corn (Zea mays) and soybean (Glycine max) in response to long-term glyphosate (PowerMAX™, Monsanto Company, MO, USA) treatment. A long-term glyphosate application study was carried out using rhizoboxes under greenhouse conditions with soil previously having no history of glyphosate exposure. Rhizosphere soil was collected from the rhizoboxes after four growing periods. Soil microbial community composition was analyzed using microbial phospholipid fatty acid (PLFA) analysis. Total RNA was extracted from rhizosphere soil, and samples were analyzed using RNA-Seq analysis. A total of 20-28 million bacterial sequences were obtained for each sample. Transcript abundance was compared between control and glyphosate-treated samples using edgeR. Overall rhizosphere bacterial metatranscriptomes were dominated by transcripts related to RNA and carbohydrate metabolism. We identified 67 differentially expressed bacterial transcripts from the rhizosphere. Transcripts downregulated following glyphosate treatment involved carbohydrate and amino acid metabolism, and upregulated transcripts involved protein metabolism and respiration. Additionally, bacterial transcripts involving nutrients, including iron, nitrogen, phosphorus, and potassium, were also affected by long-term glyphosate application. Overall, most bacterial and all fungal PLFA biomarkers decreased after glyphosate treatment compared to the control. These results demonstrate that long-term glyphosate use can affect rhizosphere bacterial activities and potentially shift bacterial community composition favoring more glyphosate-tolerant bacteria. PMID:26901800

  6. Multiple gene sequence analysis using genes of the bacterial DNA repair pathway

    Directory of Open Access Journals (Sweden)

    Miguel Rotelok Neto

    2015-06-01

    Full Text Available The ability to recognize and repair abnormal DNA structures is common to all forms of life. Physiological studies and genomic sequencing of a variety of bacterial species have identified an incredible diversity of DNA repair pathways. Despite the amount of available genes in public database, the usual method to place genomes in a taxonomic context is based mainly on the 16S rRNA or housekeeping genes. Thus, the relationships among genomes remain poorly understood. In this work, an approach of multiple gene sequence analysis based on genes of DNA repair pathway was used to compare bacterial genomes. Housekeeping and DNA repair genes were searched in 872 completely sequenced bacterial genomes. Seven DNA repair and housekeeping genes from distinct metabolic pathways were selected, aligned, edited and concatenated head-to-tail to form a super-gene. Results showed that the multiple gene sequence analysis using DNA repair genes had better resolution at class level than the housekeeping genes. As housekeeping genes, the DNA repair genes were advantageous to separate bacterial groups at low taxonomic levels and also sensitive to genes derived from horizontal transfer.

  7. Subgingival bacterial colonization profiles correlate with gingival tissue gene expression

    Directory of Open Access Journals (Sweden)

    Handfield Martin

    2009-10-01

    Full Text Available Abstract Background Periodontitis is a chronic inflammatory disease caused by the microbiota of the periodontal pocket. We investigated the association between subgingival bacterial profiles and gene expression patterns in gingival tissues of patients with periodontitis. A total of 120 patients undergoing periodontal surgery contributed with a minimum of two interproximal gingival papillae (range 2-4 from a maxillary posterior region. Prior to tissue harvesting, subgingival plaque samples were collected from the mesial and distal aspects of each tissue sample. Gingival tissue RNA was extracted, reverse-transcribed, labeled, and hybridized with whole-genome microarrays (310 in total. Plaque samples were analyzed using checkerboard DNA-DNA hybridizations with respect to 11 bacterial species. Random effects linear regression models considered bacterial levels as exposure and expression profiles as outcome variables. Gene Ontology analyses summarized the expression patterns into biologically relevant categories. Results Wide inter-species variation was noted in the number of differentially expressed gingival tissue genes according to subgingival bacterial levels: Using a Bonferroni correction (p -7, 9,392 probe sets were differentially associated with levels of Tannerella forsythia, 8,537 with Porphyromonas gingivalis, 6,460 with Aggregatibacter actinomycetemcomitans, 506 with Eikenella corrodens and only 8 with Actinomyces naeslundii. Cluster analysis identified commonalities and differences among tissue gene expression patterns differentially regulated according to bacterial levels. Conclusion Our findings suggest that the microbial content of the periodontal pocket is a determinant of gene expression in the gingival tissues and provide new insights into the differential ability of periodontal species to elicit a local host response.

  8. Exploring new roles for the rpoS gene in the survival and virulence of the fire blight pathogen Erwinia amylovora.

    Science.gov (United States)

    Santander, Ricardo D; Monte-Serrano, Mercedes; Rodríguez-Herva, José J; López-Solanilla, Emilia; Rodríguez-Palenzuela, Pablo; Biosca, Elena G

    2014-12-01

    Erwinia amylovora causes fire blight in economically important plants of the family Rosaceae. This bacterial pathogen spends part of its life cycle coping with starvation and other fluctuating environmental conditions. In many Gram-negative bacteria, starvation and other stress responses are regulated by the sigma factor RpoS. We obtained an E. amylovora rpoS mutant to explore the role of this gene in starvation responses and its potential implication in other processes not yet studied in this pathogen. Results showed that E. amylovora needs rpoS to develop normal starvation survival and viable but nonculturable (VBNC) responses. Furthermore, this gene contributed to stationary phase cross-protection against oxidative, osmotic, and acid stresses and was essential for cross-protection against heat shock, but nonessential against acid shock. RpoS also mediated regulation of motility, exopolysaccharide synthesis, and virulence in immature loquats, but not in pear plantlets, and contributed to E. amylovora survival in nonhost tissues during incompatible interactions. Our results reveal some unique roles for the rpoS gene in E. amylovora and provide new knowledge on the regulation of different processes related to its ecology, including survival in different environments and virulence in immature fruits. PMID:25331301

  9. Propionibacterium acnes CAMP factor and host acid sphingomyelinase contribute to bacterial virulence: potential targets for inflammatory acne treatment.

    Directory of Open Access Journals (Sweden)

    Teruaki Nakatsuji

    Full Text Available BACKGROUND: In the progression of acne vulgaris, the disruption of follicular epithelia by an over-growth of Propionibacterium acnes (P. acnes permits the bacteria to spread and become in contact with various skin and immune cells. METHODOLOGY/PRINCIPAL FINDINGS: We have demonstrated in the present study that the Christie, Atkins, Munch-Peterson (CAMP factor of P. acnes is a secretory protein with co-hemolytic activity with sphingomyelinase that can confer cytotoxicity to HaCaT keratinocytes and RAW264.7 macrophages. The CAMP factor from bacteria and acid sphingomyelinase (ASMase from the host cells were simultaneously present in the culture supernatant only when the cells were co-cultured with P. acnes. Either anti-CAMP factor serum or desipramine, a selective ASMase inhibitor, significantly abrogated the P. acnes-induced cell death of HaCaT and RAW264.7 cells. Intradermal injection of ICR mouse ears with live P. acnes induced considerable ear inflammation, macrophage infiltration, and an increase in cellular soluble ASMase. Suppression of ASMase by systemic treatment with desipramine significantly reduced inflammatory reaction induced by intradermal injection with P. acnes, suggesting the contribution of host ASMase in P. acnes-induced inflammatory reaction in vivo. Vaccination of mice with CAMP factor elicited a protective immunity against P. acnes-induced ear inflammation, indicating the involvement of CAMP factor in P. acnes-induced inflammation. Most notably, suppression of both bacterial CAMP factor and host ASMase using vaccination and specific antibody injection, respectively, cooperatively alleviated P. acnes-induced inflammation. CONCLUSIONS/SIGNIFICANCE: These findings envision a novel infectious mechanism by which P. acnes CAMP factor may hijack host ASMase to amplify bacterial virulence to degrade and invade host cells. This work has identified both CAMP factor and ASMase as potential molecular targets for the development of drugs

  10. Comparison of two DNA microarrays for detection of plasmid-mediated antimicrobial resistance and virulence factor genes in clinical isolates of Enterobacteriaceae and non-Enterobacteriaceae.

    LENUS (Irish Health Repository)

    Walsh, Fiona

    2010-06-01

    A DNA microarray was developed to detect plasmid-mediated antimicrobial resistance (AR) and virulence factor (VF) genes in clinical isolates of Enterobacteriaceae and non-Enterobacteriaceae. The array was validated with the following bacterial species: Escherichiacoli (n=17); Klebsiellapneumoniae (n=3); Enterobacter spp. (n=6); Acinetobacter genospecies 3 (n=1); Acinetobacterbaumannii (n=1); Pseudomonasaeruginosa (n=2); and Stenotrophomonasmaltophilia (n=2). The AR gene profiles of these isolates were identified by polymerase chain reaction (PCR). The DNA microarray consisted of 155 and 133 AR and VF gene probes, respectively. Results were compared with the commercially available Identibac AMR-ve Array Tube. Hybridisation results indicated that there was excellent correlation between PCR and array results for AR and VF genes. Genes conferring resistance to each antibiotic class were identified by the DNA array. Unusual resistance genes were also identified, such as bla(SHV-5) in a bla(OXA-23)-positive carbapenem-resistant A. baumannii. The phylogenetic group of each E. coli isolate was verified by the array. These data demonstrate that it is possible to screen simultaneously for all important classes of mobile AR and VF genes in Enterobacteriaceae and non-Enterobacteriaceae whilst also assigning a correct phylogenetic group to E. coli isolates. Therefore, it is feasible to test clinical Gram-negative bacteria for all known AR genes and to provide important information regarding pathogenicity simultaneously.

  11. Development of a miniaturized DNA microarray for identification of 66 virulence genes of Legionella pneumophila

    Directory of Open Access Journals (Sweden)

    Mariusz Żak

    2011-12-01

    Full Text Available Introduction:For the last five years, Legionella sp. infections and legionnaire’s disease in Poland have been receiving a lot of attention, because of the new regulations concerning microbiological quality of drinking water. This was the inspiration to search for and develop a new assay to identify many virulence genes of Legionella pneumophila to better understand their distribution in environmental and clinical strains. The method might be an invaluable help in infection risk assessment and in epidemiological investigations.Material/Methods:The microarray is based on Array Tube technology. It contains 3 positive and 1 negative control. Target genes encode structural elements of T4SS, effector proteins and factors not related to T4SS. Probes were designed using OligoWiz software and data analyzed using IconoClust software. To isolate environmental and clinical strains, BAL samples and samples of hot water from different and independent hot water distribution systems of public utility buildings were collected.Results.We have developed a miniaturized DNA microarray for identification of 66 virulence genes of L. pneumophila. The assay is specific to L. pneumophila sg 1 with sensitivity sufficient to perform the assay using DNA isolated from a single L. pneumophila colony. Seven environmental strains were analyzed. Two exhibited a hybridization pattern distinct from the reference strain.Discussion:The method is time- and cost-effective. Initial studies have shown that genes encoding effector proteins may vary among environmental strains. Further studies might help to identify set of genes increasing the risk of clinical disease and to determine the pathogenic potential of environmental strains.

  12. Antimicrobial resistance, virulence genes, and genetic lineages of Staphylococcus pseudintermedius in healthy dogs in tunisia.

    Science.gov (United States)

    Gharsa, Haythem; Ben Slama, Karim; Gómez-Sanz, Elena; Lozano, Carmen; Klibi, Naouel; Jouini, Ahlem; Messadi, Lilia; Boudabous, Abdellatif; Torres, Carmen

    2013-08-01

    Nasal swabs of 100 healthy dogs were obtained in 2011 in Tunisia and tested for Staphylococcus pseudintermedius recovery. Antimicrobial resistance profile and virulence gene content were determined. Multilocus-sequence-typing (MLST) and SmaI-pulsed-field gel electrophoresis (PFGE) were investigated. S. pseudintermedius was recovered in 55 of the 100 tested samples (55 %), and one isolate per sample was further studied. All 55 S. pseudintermedius isolates were susceptible to methicillin (MSSP) but showed resistance to the following antimicrobials (% resistant isolates/resistance gene): penicillin (56.4/blaZ), tetracycline (40/tetM), trimethoprim-sulfamethoxazole (23.7), fusidic acid (9), kanamycin (3.7/aph(3´)-Ia), erythromycin-clindamycin (1.8/erm(B)), streptomycin (1.8/ant(6)-Ia), chloramphenicol (1.8) and ciprofloxacin (1.8). The following toxin genes were identified (% of isolates): lukS/F-I (98.2), expA (5.5), se-int (98.2), sec canine (1.8), siet (100), sea (5.5), seb (3.6), sec (10.9), sed (54.5), sei (5.5), sej (29.1), sek (3.6), ser (9.1), and hlg v (38.2). Ten different sequence-types were detected among 11 representative MSSP isolates: ST20, ST44, ST69, ST70, ST78, ST100, ST108, ST160, ST161, and ST162, the last three ones revealing novel alleles or allele combinations. Eleven different PFGE-patterns were identified in these isolates. The nares of healthy dogs could be a reservoir of antimicrobial resistant and virulent MSSP, highlighting the presence of the recently described exfoliating gene expA and several enterotoxin genes. PMID:23686400

  13. Ionizing radiation and bacterial challenge alter splenic cytokine gene expression

    International Nuclear Information System (INIS)

    Irradiation increases susceptibility to bacterial infection. Exogenous proinflammatory cytokines can alter the response of mice to γradiation, but the role of endogenous inflammatory cytokines after bacterial infection in irradiated animals is not known. Gene expression of hematopoietic (GM-CSF) and proinflammatory (IL-1β, IL-6 and TNF-α) cytokines were examined in spleens of B6D2F1/J female mice after irradiation alone (1.0- and 7.0-Gy), and after irradiation followed by Klebsiella pneumoniae s.c. challenge 4 days postirradiation by using the reverse transcription-polymerase chain reaction (RT-PCR) and Southern blot hybridization. At 4, 8, and 24 h after bacterial challenge in 7.0-Gy-irradiated mice, GM-CSF mRNA increased (p<0.05). TNF-α mRNA in irradiated mice were slightly decreased, whereas after bacterial challenge, TNF-α mRNA elevated at 30 h in 7.0-Gy-irradiated mice; at 4, and 8 h in 1.0-Gy-irradiated mice, and at 1 h in sham-irradiated mice (p<0.05). IL-6 mRNA displayed a biphasic response in 7.0-Gy-irradiated mice, and, after bacterial challenge, in both irradiated mice (1.0- and 7.0-Gy) and sham-irradiated mice. IL-1β mRNA remained at or below normal for 8 h and increased at 24 h after bacterial challenge on day 4 in 7.0-Gy-irradiated mice. These results indicate that sublethal gamma radiation alters the patterns of the hematopoietic and proinflammatory cytokine responses to bacterial challenge in vivo. Consequently, treatment protocols may need to take into account changes in cytokine gene responses to resolve infection after irradiation. (author)

  14. Diversity of antimicrobial resistance and virulence genes in methicillin-resistant non-Staphylococcus aureus staphylococci from veal calves.

    Science.gov (United States)

    Argudín, M Angeles; Vanderhaeghen, Wannes; Butaye, Patrick

    2015-04-01

    In this study we determined whether methicillin-resistant non-Staphylococcus aureus (MRNAS) from veal calves may be a potential reservoir of antimicrobial-resistance and virulence genes. Fifty-eight MRNAS were studied by means of DNA-microarray and PCR for detection of antimicrobial resistance and virulence genes. The isolates carried a variety of antimicrobial-resistance genes [aacA-aphD, aadD, aph3, aadE, sat, spc, ampA, erm(A), erm(B), erm(C), erm(F), erm(T), lnu(A), msr(A)-msr(B), vga(A), mph(C), tet(K), tet(M), tet(L), cat, fexA, dfrA, dfrD, dfrG, dfrK, cfr, fusB, fosB, qacA, qacC, merA-merB]. Some isolates carried resistance genes without showing the corresponding resistance phenotype. Most MRNAS carried typical S. aureus virulence factors like proteases (sspP) and enterotoxins (seg) genes. Most Staphylococcus epidermidis isolates carried the arginine catabolic element, and nearly 40% of the Staphylococcus sciuri isolates carried leukocidins, and/or fibronectin-binding protein genes. MRNAS were highly multi-resistant and represent an important reservoir of antimicrobial resistance and virulence genes. PMID:25637268

  15. Cinnamide Derivatives of d-Mannose as Inhibitors of the Bacterial Virulence Factor LecB from Pseudomonas aeruginosa.

    Science.gov (United States)

    Sommer, Roman; Hauck, Dirk; Varrot, Annabelle; Wagner, Stefanie; Audfray, Aymeric; Prestel, Andreas; Möller, Heiko M; Imberty, Anne; Titz, Alexander

    2015-12-01

    Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen with high antibiotic resistance. Its lectin LecB was identified as a virulence factor and is relevant in bacterial adhesion and biofilm formation. Inhibition of LecB with carbohydrate-based ligands results in a decrease in toxicity and biofilm formation. We recently discovered two classes of potent drug-like glycomimetic inhibitors, that is, sulfonamides and cinnamides of d-mannose. Here, we describe the chemical synthesis and biochemical evaluation of more than 20 derivatives with increased potency compared to the unsubstituted cinnamide. The structure-activity relationship (SAR) obtained and the extended biophysical characterization allowed the experimental determination of the binding mode of these cinnamides with LecB. The established surface binding mode now allows future rational structure-based drug design. Importantly, all glycomimetics tested showed extended receptor residence times with half-lives in the 5-20 min range, a prerequisite for therapeutic application. Thus, the glycomimetics described here provide an excellent basis for future development of anti-infectives against this multidrug-resistant pathogen. PMID:27308201

  16. Defence against methylglyoxal in Group A Streptococcus: a role for Glyoxylase I in bacterial virulence and survival in neutrophils?

    Science.gov (United States)

    Zhang, May M; Ong, Cheryl-lynn Y; Walker, Mark J; McEwan, Alastair G

    2016-03-01

    Methylglyoxal is a dicarbonyl compound that acts as a toxic electrophile in biological systems. Methylglyoxal is produced in certain bacteria as a byproduct of glycolysis through methylglyoxal synthase. Like many bacteria, Group A Streptococcus (GAS), a Gram-positive human pathogen responsible for a wide spectrum of diseases, uses a two-step glyoxalase system to remove methylglyoxal. However, bioinformatic analysis revealed that no homologue of methylglyoxal synthase is present in GAS, suggesting that the role of the glyoxalase system is to detoxify methylglyoxal produced by the host. In this study, we investigated the role of methylglyoxal detoxification in the pathogenesis of GAS. A mutant (5448ΔgloA), deficient in glyoxylase I (S-lactoylglutathione lyase), was constructed and tested for susceptibility to methylglyoxal, human neutrophil survival and virulence in a murine model of infection. 5448ΔgloA was more sensitive to methylglyoxal and was also more susceptible to human neutrophil killing. Inhibition of neutrophil myeloperoxidase rescued the gloA-deficient mutant indicating that this enzyme was required for methylglyoxal production. Furthermore, the 5448ΔgloA mutant was slower at disseminating into the blood in the murine model. These data suggest that neutrophils produce methylglyoxal as an antimicrobial agent during bacterial infection, and the glyoxalase system is part of the GAS defence against the innate immune system during pathogenesis. PMID:26702634

  17. Identification of seven novel virulence genes from Xanthomonas citri subsp. citri by Tn5-based random mutagenesis.

    Science.gov (United States)

    Song, Xue; Guo, Jing; Ma, Wen-xiu; Ji, Zhi-yuan; Zou, Li-fang; Chen, Gong-you; Zou, Hua-song

    2015-05-01

    To identify novel virulence genes, a mutant library of Xanthomonas citri subsp. citri 29-1 was produced using EZ-Tn5 transposon and the mutants were inoculated into susceptible grapefruit. Forty mutants with altered virulence phenotypes were identified. Nine of the mutants showed a complete loss of citrus canker induction, and the other 31 mutants resulted in attenuated canker symptoms. Southern blot analysis revealed that each of the mutants carried a single copy of Tn5. The flanking sequence was identified by plasmid rescue and 18 different ORFs were identified in the genome sequence. Of these 18 ORFs, seven had not been previously associated with the virulence of X. citri subsp. citri and were therefore confirmed by complementation analysis. Real-time PCR analysis showed that the seven genes were upregulated when the bacteria were grown in citrus plants, suggesting that the expression of these genes was essential for canker development. PMID:25935304

  18. Distribution of genes encoding virulence factors and molecular analysis of Shigella spp. isolated from patients with diarrhea in Kerman, Iran.

    Science.gov (United States)

    Hosseini Nave, Hossein; Mansouri, Shahla; Emaneini, Mohammad; Moradi, Mohammad

    2016-03-01

    Shigella is one of the important causes of diarrhea worldwide. Shigella has several virulence factors contributing in colonization and invasion of epithelial cells and eventually death of host cells. The present study was performed in order to investigate the distribution of virulence factors genes in Shigella spp. isolated from patients with acute diarrhea in Kerman, Iran as well as the genetic relationship of these isolates. A total of 56 isolates including 31 S. flexneri, 18 S. sonnei and 7 S. boydii were evaluated by polymerase chain reaction (PCR) for the presence of 11 virulence genes (ipaH, ial, set1A, set1B, sen, virF, invE, sat, sigA, pic and sepA). Then, the clonal relationship of these strains was analyzed by multilocus variable-number tandem repeat analysis (MLVA) method. All isolates were positive for ipaH gene. The other genes include ial, invE and virF were found in 80.4%, 60.7% and 67.9% of the isolates, respectively. Both set1A and set1B were detected in 32.3% of S. flexneri isolates, whereas 66.1% of the isolates belonging to different serogroup carried sen gene. The sat gene was present in all S. flexneri isolates, but not in the S. sonnei and S. boydii isolates. The result showed, 30.4% of isolates were simultaneously positive and the rest of the isolates were negative for sepA and pic genes. The Shigella isolates were divided into 29 MLVA types. This study, for the first time, investigated distribution of 11 virulence genes in Shigella spp. Our results revealed heterogeneity of virulence genes in different Shigella serogroups. Furthermore, the strains belonging to the same species had little diversity. PMID:26654792

  19. Virulence determinants of uropathogenic Escherichia coli and Proteus mirabilis.

    Science.gov (United States)

    Mobley, H L; Island, M D; Massad, G

    1994-11-01

    The urinary tract is among the most common sites of bacterial infection and E. coli is by far the most common infecting agent. In patients with urinary catheters in place or structural abnormalities of the urinary tract, Proteus mirabilis is also a frequent isolate. To study virulence of these bacterial species, we have isolated the genes that encode putative virulence factors, constructed specific mutations within these genes, introduced the mutation back into the wild type strain by allelic exchange, and analyzed these mutants for virulence in appropriate in vitro and in vivo models. Specific virulence markers have been identified for strains that cause urinary tract infection. For E. coli, these include P fimbriae, S fimbriae, hemolysin, aerobactin, serum resistance, and a small group of O-serotypes. Redundant virulence factors must be present in these organisms as mutation of the most clearly identified epidemiological marker, P fimbriae, does not result in attenuation of a virulent strain. For P. mirabilis, urease appears to contribute most significantly to virulence. Fimbriae play a significant but more subtle role in colonization. Hemolysin, although potently cytotoxic to renal cells in vitro, does not appear to contribute significantly to the pathogenesis of ascending urinary tract infection. We can conclude that the pathogenesis of urinary tract infection and acute pyelonephritis caused by uropathogenic E. coli and P. mirabilis are multifactorial, as mutation of single genes rarely causes significant attenuation of virulence. PMID:7869662

  20. Molecular cloning of cellulase genes from indigenous bacterial isolates

    International Nuclear Information System (INIS)

    Indigenous cellulolytic bacterial isolates having high activities in degrading carboxymethyl cellulose (CMC) were isolated from local environments. Identification of these isolates were performed by molecular techniques. By using polymerase chain reaction (PCR) techniques, PCR products encoding cellulase gene were amplified from the total genomic DNAs. Purified PCR product was successfully cloned and expressed in Escherichia coli host system. The complete nucleotide sequences of the cellulase genes determined. The analysis of amino acid sequences deduced from the genes indicated that the cloned DNA fragments show high homology to those of endoglucanase genes of family GH5. All cloned genes consist of an N-terminal signal peptide, a catalytic domain of family 5 glycosyl hydrolase and a cellulose-binding domain of family III. (Author)

  1. Loss of σI affects heat-shock response and virulence gene expression in Bacillus anthracis.

    Science.gov (United States)

    Kim, Jenny Gi Yae; Wilson, Adam C

    2016-02-01

    The pathogenesis of Bacillus anthracis depends on several virulence factors, including the anthrax toxin. Loss of the alternative sigma factor σI results in a coordinate decrease in expression of all three toxin subunits. Our observations suggest that loss of σI alters the activity of the master virulence regulator AtxA, but atxA transcription is unaffected by loss of σI. σI-containing RNA polymerase does not appear to directly transcribe either atxA or the toxin gene pagA. As in Bacillus subtilis, loss of σI in B. anthracis results in increased sensitivity to heat shock and transcription of sigI, encoding σI, is induced by elevated temperature. Encoded immediately downstream of and part of a bicistronic message with sigI is an anti-sigma factor, RsgI, which controls σI activity. Loss of RsgI has no direct effect on virulence gene expression. sigI appears to be expressed from both the σI and σA promoters, and transcription from the σA promoter is likely more significant to virulence regulation. We propose a model in which σI can be induced in response to heat shock, whilst, independently, σI is produced under non-heat-shock, toxin-inducing conditions to indirectly regulate virulence gene expression. PMID:26744224

  2. Highly Frequent Mutations in Negative Regulators of Multiple Virulence Genes in Group A Streptococcal Toxic Shock Syndrome Isolates

    OpenAIRE

    Ikebe, Tadayoshi; Ato, Manabu; Matsumura, Takayuki; Hasegawa, Hideki; Sata, Tetsutaro; Kobayashi, Kazuo; Watanabe, Haruo

    2010-01-01

    Streptococcal toxic shock syndrome (STSS) is a severe invasive infection characterized by the sudden onset of shock and multiorgan failure; it has a high mortality rate. Although a number of studies have attempted to determine the crucial factors behind the onset of STSS, the responsible genes in group A Streptococcus have not been clarified. We previously reported that mutations of csrS/csrR genes, a two-component negative regulator system for multiple virulence genes of Streptococcus pyogen...

  3. Anaerobes and bacterial vaginosis in pregnancy: virulence factors contributing to vaginal colonisation.

    Science.gov (United States)

    Africa, Charlene W J; Nel, Janske; Stemmet, Megan

    2014-07-01

    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. PMID:25014248

  4. Anaerobes and Bacterial Vaginosis in Pregnancy: Virulence Factors Contributing to Vaginal Colonisation

    Directory of Open Access Journals (Sweden)

    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.

  5. Bacterial Cellular Engineering by Genome Editing and Gene Silencing

    Directory of Open Access Journals (Sweden)

    Nobutaka Nakashima

    2014-02-01

    Full Text Available Genome editing is an important technology for bacterial cellular engineering, which is commonly conducted by homologous recombination-based procedures, including gene knockout (disruption, knock-in (insertion, and allelic exchange. In addition, some new recombination-independent approaches have emerged that utilize catalytic RNAs, artificial nucleases, nucleic acid analogs, and peptide nucleic acids. Apart from these methods, which directly modify the genomic structure, an alternative approach is to conditionally modify the gene expression profile at the posttranscriptional level without altering the genomes. This is performed by expressing antisense RNAs to knock down (silence target mRNAs in vivo. This review describes the features and recent advances on methods used in genomic engineering and silencing technologies that are advantageously used for bacterial cellular engineering.

  6. Targeted mutagenesis in pathogenic Leptospira species: disruption of the LigB gene does not affect virulence in animal models of leptospirosis.

    Science.gov (United States)

    Croda, Julio; Figueira, Claudio Pereira; Wunder, Elsio A; Santos, Cleiton S; Reis, Mitermayer G; Ko, Albert I; Picardeau, Mathieu

    2008-12-01

    The pathogenic mechanisms of Leptospira interrogans, the causal agent of leptospirosis, remain largely unknown. This is mainly due to the lack of tools for genetically manipulating pathogenic Leptospira species. Thus, homologous recombination between introduced DNA and the corresponding chromosomal locus has never been demonstrated for this pathogen. Leptospiral immunoglobulin-like repeat (Lig) proteins were previously identified as putative Leptospira virulence factors. In this study, a ligB mutant was constructed by allelic exchange in L. interrogans; in this mutant a spectinomycin resistance (Spc(r)) gene replaced a portion of the ligB coding sequence. Gene disruption was confirmed by PCR, immunoblot analysis, and immunofluorescence studies. The ligB mutant did not show decrease virulence compared to the wild-type strain in the hamster model of leptospirosis. In addition, inoculation of rats with the ligB mutant induced persistent colonization of the kidneys. Finally, LigB was not required to mediate bacterial adherence to cultured cells. Taken together, our data provide the first evidence of site-directed homologous recombination in pathogenic Leptospira species. Furthermore, our data suggest that LigB does not play a major role in dissemination of the pathogen in the host and in the development of acute disease manifestations or persistent renal colonization. PMID:18809657

  7. The gpsX gene encoding a glycosyltransferase is important for polysaccharide production and required for full virulence in Xanthomonas citri subsp. citri

    Directory of Open Access Journals (Sweden)

    Li Jinyun

    2012-03-01

    Full Text Available Abstract Background The Gram-negative bacterium Xanthomonas citri subsp. citri (Xac causes citrus canker, one of the most destructive diseases of citrus worldwide. In our previous work, a transposon mutant of Xac strain 306 with an insertion in the XAC3110 locus was isolated in a screening that aimed at identifying genes related to biofilm formation. The XAC3110 locus was named as bdp24 for biofilm-defective phenotype and the mutant was observed to be affected in extracellular polysaccharide (EPS and lipopolysaccharide (LPS biosynthesis and cell motility. In this study, we further characterized the bdp24 (XAC3110 gene (designated as gpsX using genetic complementation assays and expanded the knowledge about the function of the gpsX gene in Xac pathogenesis by investigating the roles of gpsX in EPS and LPS production, cell motility, biofilm formation on host leaves, stress tolerance, growth in planta, and host virulence of the citrus canker bacterium. Results The gpsX gene encodes a putative glycosyltransferase, which is highly conserved in the sequenced strains of Xanthomonas. Mutation of gpsX resulted in a significant reduction of the amount of EPS and loss of two LPS bands visualized on sodium dodecylsulphate- polyacrylamide gels. Biofilm assays revealed that the gpsX mutation affected biofilm formation by Xac on abiotic and biotic surfaces. The gpsX mutant showed delayed bacterial growth and caused reduced development of disease symptoms in susceptible citrus leaves. The gpsX mutant was more sensitive than the wild-type strain to various stresses, including the H2O2 oxidative stress. The mutant also showed attenuated ability in cell motility but not in flagellar formation. Quantitative reverse transcription-PCR assays indicated that mutation of gpsX did not affect the expression of virulence genes such as pthA in Xac strain 306. The affected phenotypes of the gpsX mutant could be complemented to wild-type levels by the intact gpsX gene

  8. Resistance of Antimicrobial Peptide Gene Transgenic Rice to Bacterial Blight

    Institute of Scientific and Technical Information of China (English)

    WANG Wei; WU Chao; LIU Mei; LIU Xu-ri; Hu Guo-cheng; SI Hua-min; SUN Zong-xiu; LIU Wen-zhen; Fu Ya-ping

    2011-01-01

    Antimierobial peptide is a polypeptide with antimicrobial activity.Antimicrobial peptide genes Np3 and Np5 from Chinese shrimp (Fenneropenaeus Chinensis) were integrated into Oryza sativa L.subsp.japonica cv.Aichi ashahi by Agrobacterium mediated transformation system.PCR analysis showed that the positive ratios of Np3 and Np5 were 36% and 45% in T0 generation,respectively.RT-PCR analysis showed that the antimicrobial peptide genes were expressed in T1 generation,and there was no obvious difference in agronomic traits between transgenic plants and non-transgenic plants.Four Np3 and Np5 transgenic lines in T1 generation were inoculated with ×anthomonas oryzae pv.oryzae strain CR4,and all the four transgenic lines had significantly enhanced resistance to bacterial blight caused by the strain CR4.The Np5 transgenic lines also showed higher resistance to bacterial blight caused by strains JS97-2,Zhe 173 and OS-225.It is suggested that transgenic lines with Np5 gene might possess broad spectrum resistance to rice bacterial blight.

  9. Molecular Analysis and Identification of Virulence Gene on pRST98 from Multi-Drug Resistant Salmonella typhi

    Institute of Scientific and Technical Information of China (English)

    RuiHuang; ShuyanWu; XueguangZhang; YanyunZhang

    2005-01-01

    pRST98 is a large and conjugative resistant plasmid (R plasmid) of 98.6 mega-dalton from multi-drug resistant Salmonella typhi (S. typhi), which was classified to incompatibility group C (Inc C). It has been found that pRST98 made its host bacteria not only antibiotic resistant but also more virulent. In this study we explored the possibility of plasmid pRsr98 in S. typhi carrying the Salmonella plasmid virulence gene - spv. The plasmid pRST98 was isolated, purified and then digested by nine restriction endonucleases to make the plasmid enzyme profile. Spv-specific PCR and Southern blot were applied to identify the virulence gene on pRsr98. The amplified spv fragments spvR and spvB were cloned into pGEM-T EASY and then the DNA sequences were analysed. The fragments of pRST98 digested by endonucleases Bgl II, Pst I and Sac II were identified, which may be useful for molecular analysis and further epidemiological surveillance of pRsT98. The results of PCR and Southern blot showed that spv homologous genetic sequence which had been found in all pathogenesis Salmonella spp. except S. typhi was also presented on pRST98. The ORF of spvR and spvB of pRsr98 were 894 bp and 1,776 bp, respectively. They have more than 99% homology with that of spvR and spvB on virulence plasmid in S. typhmurium. The genotype research on pRST98 revealed that there is a plasmid carrying genes responsible for drug resistance and virulence in S. typhi. This is the first report for such kind chimerical plasmid in S. typhi. Cellular & Molecular Immunology. 2005;2(2):136-140.Key Words: s. typhi, R plasmid, virulence gene

  10. An HD-domain phosphodiesterase mediates cooperative hydrolysis of c-di-AMP to affect bacterial growth and virulence

    Science.gov (United States)

    Huynh, TuAnh Ngoc; Luo, Shukun; Pensinger, Daniel; Sauer, John-Demian; Tong, Liang; Woodward, Joshua J.

    2015-01-01

    The nucleotide cyclic di-3′,5′- adenosine monophosphate (c-di-AMP) was recently identified as an essential and widespread second messenger in bacterial signaling. Among c-di-AMP–producing bacteria, altered nucleotide levels result in several physiological defects and attenuated virulence. Thus, a detailed molecular understanding of c-di-AMP metabolism is of both fundamental and practical interest. Currently, c-di-AMP degradation is recognized solely among DHH-DHHA1 domain-containing phosphodiesterases. Using chemical proteomics, we identified the Listeria monocytogenes protein PgpH as a molecular target of c-di-AMP. Biochemical and structural studies revealed that the PgpH His-Asp (HD) domain bound c-di-AMP with high affinity and specifically hydrolyzed this nucleotide to 5′-pApA. PgpH hydrolysis activity was inhibited by ppGpp, indicating a cross-talk between c-di-AMP signaling and the stringent response. Genetic analyses supported coordinated regulation of c-di-AMP levels in and out of the host. Intriguingly, a L. monocytogenes mutant that lacks c-di-AMP phosphodiesterases exhibited elevated c-di-AMP levels, hyperinduced a host type-I IFN response, and was significantly attenuated for infection. Furthermore, PgpH homologs, which belong to the 7TMR-HD family, are widespread among hundreds of c-di-AMP synthesizing microorganisms. Thus, PgpH represents a broadly conserved class of c-di-AMP phosphodiesterase with possibly other physiological functions in this crucial signaling network. PMID:25583510

  11. Adhesion of human and animal escherichia coli strains in association with their virulence-associated genes and phylogenetic origins

    DEFF Research Database (Denmark)

    Fr̈mmel, Ulrike; R̈diger, Stefan; B̈hm, Alexander;

    2013-01-01

    Intestinal colonization is influenced by the ability of the bacterium to inhabit a niche, which is based on the expression of colonization factors. Escherichia coli carries a broad range of virulence-associated genes (VAGs) which contribute to intestinal (inVAGs) and extraintestinal (ex...

  12. A spectrum of CodY activities drives metabolic reorganization and virulence gene expression in Staphylococcus aureus.

    Science.gov (United States)

    Waters, Nicholas R; Samuels, David J; Behera, Ranjan K; Livny, Jonathan; Rhee, Kyu Y; Sadykov, Marat R; Brinsmade, Shaun R

    2016-08-01

    The global regulator CodY controls the expression of dozens of metabolism and virulence genes in the opportunistic pathogen Staphylococcus aureus in response to the availability of isoleucine, leucine and valine (ILV), and GTP. Using RNA-Seq transcriptional profiling and partial activity variants, we reveal that S. aureus CodY activity grades metabolic and virulence gene expression as a function of ILV availability, mediating metabolic reorganization and controlling virulence factor production in vitro. Strains lacking CodY regulatory activity produce a PIA-dependent biofilm, but development is restricted under conditions that confer partial CodY activity. CodY regulates the expression of thermonuclease (nuc) via the Sae two-component system, revealing cascading virulence regulation and factor production as CodY activity is reduced. Proteins that mediate the host-pathogen interaction and subvert the immune response are shut off at intermediate levels of CodY activity, while genes coding for enzymes and proteins that extract nutrients from tissue, that kill host cells, and that synthesize amino acids are among the last genes to be derepressed. We conclude that S. aureus uses CodY to limit host damage to only the most severe starvation conditions, providing insight into one potential mechanism by which S. aureus transitions from a commensal bacterium to an invasive pathogen. PMID:27116338

  13. New insights about excisable pathogenicity islands in Salmonella and their contribution to virulence.

    Science.gov (United States)

    Nieto, Pamela A; Pardo-Roa, Catalina; Salazar-Echegarai, Francisco J; Tobar, Hugo E; Coronado-Arrázola, Irenice; Riedel, Claudia A; Kalergis, Alexis M; Bueno, Susan M

    2016-05-01

    Pathogenicity islands (PAIs) are regions of the chromosome of pathogenic bacteria that harbor virulence genes, which were probably acquired by lateral gene transfer. Several PAIs can excise from the bacterial chromosome by site-specific recombination and in this review have been denominated "excisable PAIs". Here, the characteristic of some of the excisable PAIs from Salmonella enterica and the possible role and impact of the excision process on bacterial virulence is discussed. Understanding the role of PAI excision could provide important insights relative to the emergence, evolution and virulence of pathogenic enterobacteria. PMID:26939722

  14. Cooperation and the evolutionary ecology of bacterial virulence: the Bacillus cereus group as a novel study system.

    Science.gov (United States)

    Raymond, Ben; Bonsall, Michael B

    2013-08-01

    How significant is social evolution theory for the maintenance of virulence in natural populations? We assume that secreted, distantly acting virulence factors are highly likely to be cooperative public goods. Using this assumption, we discuss and critically assess the potential importance of social interactions for understanding the evolution, diversity and distribution of virulence in the Bacillus cereus group, a novel study system for microbial social biology. We conclude that dynamic equilibria in Cry toxin production, as well as strong spatial structure and population bottlenecks in hosts are the main ecological factors maintaining the cooperative secretion of virulence factors and argue that collective action has contributed to the evolution of narrow host range. Non-linearities in the benefits associated with public goods, as well as the lack of private secretion systems in the Firmicutes may also explain the prevalence and importance of distantly acting virulence factors in B. cereus and its relatives. PMID:23702950

  15. Non mycobacterial virulence genes in the genome of the emerging pathogen Mycobacterium abscessus.

    Directory of Open Access Journals (Sweden)

    Fabienne Ripoll

    Full Text Available Mycobacterium abscessus is an emerging rapidly growing mycobacterium (RGM causing a pseudotuberculous lung disease to which patients with cystic fibrosis (CF are particularly susceptible. We report here its complete genome sequence. The genome of M. abscessus (CIP 104536T consists of a 5,067,172-bp circular chromosome including 4920 predicted coding sequences (CDS, an 81-kb full-length prophage and 5 IS elements, and a 23-kb mercury resistance plasmid almost identical to pMM23 from Mycobacterium marinum. The chromosome encodes many virulence proteins and virulence protein families absent or present in only small numbers in the model RGM species Mycobacterium smegmatis. Many of these proteins are encoded by genes belonging to a "mycobacterial" gene pool (e.g. PE and PPE proteins, MCE and YrbE proteins, lipoprotein LpqH precursors. However, many others (e.g. phospholipase C, MgtC, MsrA, ABC Fe(3+ transporter appear to have been horizontally acquired from distantly related environmental bacteria with a high G+C content, mostly actinobacteria (e.g. Rhodococcus sp., Streptomyces sp. and pseudomonads. We also identified several metabolic regions acquired from actinobacteria and pseudomonads (relating to phenazine biosynthesis, homogentisate catabolism, phenylacetic acid degradation, DNA degradation not present in the M. smegmatis genome. Many of the "non mycobacterial" factors detected in M. abscessus are also present in two of the pathogens most frequently isolated from CF patients, Pseudomonas aeruginosa and Burkholderia cepacia. This study elucidates the genetic basis of the unique pathogenicity of M. abscessus among RGM, and raises the question of similar mechanisms of pathogenicity shared by unrelated organisms in CF patients.

  16. Bacterial reference genes for gene expression studies by RT-qPCR: survey and analysis.

    Science.gov (United States)

    Rocha, Danilo J P; Santos, Carolina S; Pacheco, Luis G C

    2015-09-01

    The appropriate choice of reference genes is essential for accurate normalization of gene expression data obtained by the method of reverse transcription quantitative real-time PCR (RT-qPCR). In 2009, a guideline called the Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) highlighted the importance of the selection and validation of more than one suitable reference gene for obtaining reliable RT-qPCR results. Herein, we searched the recent literature in order to identify the bacterial reference genes that have been most commonly validated in gene expression studies by RT-qPCR (in the first 5 years following publication of the MIQE guidelines). Through a combination of different search parameters with the text mining tool MedlineRanker, we identified 145 unique bacterial genes that were recently tested as candidate reference genes. Of these, 45 genes were experimentally validated and, in most of the cases, their expression stabilities were verified using the software tools geNorm and NormFinder. It is noteworthy that only 10 of these reference genes had been validated in two or more of the studies evaluated. An enrichment analysis using Gene Ontology classifications demonstrated that genes belonging to the functional categories of DNA Replication (GO: 0006260) and Transcription (GO: 0006351) rendered a proportionally higher number of validated reference genes. Three genes in the former functional class were also among the top five most stable genes identified through an analysis of gene expression data obtained from the Pathosystems Resource Integration Center. These results may provide a guideline for the initial selection of candidate reference genes for RT-qPCR studies in several different bacterial species. PMID:26149127

  17. The effect of γ radiation on the expression of the virulence genes of Salmonella typhimurium and Vibrio spp

    International Nuclear Information System (INIS)

    The principle benefit of food irradiation is the reduction of food-borne bacteria in food products. However, the microbiological safety with respect to increased virulence of surviving pathogens after irradiation remains an important issue with regard to the effectiveness of food irradiation. In this study, the transcriptional changes of virulence genes of Salmonella and Vibrio spp. after γ radiation were investigated by real-time PCR (RT-PCR). Samonella typhimurium is dependent upon the products of a large number of genes located within Salmonella pathogenicity islands (SPI) on the chromosome. The expressions of seven genes including four SPI genes, hilD, ssrB, pipB, and sopD, were measured at 1 h after 1 kGy irradiation. Compared with non-irradiated controls, the expression of hilD encoded within SPI1 and sopD encoding SPI1-related effector proteins was reduced about 4- and 16-fold, respectively. The expressions of Vibrio toxin genes, vvhA, ctxA, and tdh, were also monitored during the course of a growth cycle after re-inoculation of irradiated Vibrio spp. (0.5 and 1.0 kGy). The expressions of Vibrio toxin genes tested did not increase compared with non-irradiated counterparts. Results from this study indicate that γ radiation is much more likely to reduce the virulence gene expression of surviving pathogens

  18. Detection of type III secretion system genes in Aeromonas hydrophila and their relationship with virulence in Nile tilapia.

    Science.gov (United States)

    Carvalho-Castro, G A; Lopes, C O; Leal, C A G; Cardoso, P G; Leite, R C; Figueiredo, H C P

    2010-08-26

    The goals of this study were to develop a PCR technique to detect ascV and aopB genes from the type III secretion system (T3SS), to evaluate the frequency of these genes in Aeromonas hydrophila strains isolated from diseased fish and from aquaculture environments, and to determine the relationship between the presence of these genes and virulence of A. hydrophila in Nile tilapia. The PCR assay developed here successfully detected the target genes, showing three different profiles for the strains ascV+/aopB+, ascV+/aopB-, and ascV-/aopB-. A higher frequency of ascV+/aopB+ was verified in isolates from diseased fish compared to those from aquaculture environments (PPCR technique was shown to be a specific and efficient tool for detection of T3SS, and this technique can be used for virulence typing of A. hydrophila isolates. PMID:20185253

  19. Virulence Genes and Antimicrobial Resistance Profiles of Pasteurella multocida Strains Isolated from Rabbits in Brazil

    Directory of Open Access Journals (Sweden)

    Thais Sebastiana Porfida Ferreira

    2012-01-01

    Full Text Available Pasteurella multocida is responsible for a wide range of diseases in domestic animals. In rabbits, the agent is related to nasal discharge, pneumonia, otitis media, pyometra, orchitis, abscess, and septicemia. One hundred and forty rabbits with respiratory diseases from four rabbitries in São Paulo State, Brazil were evaluated for the detection of P. multocida in their nasal cavities. A total of twenty-nine animals were positive to P. multocida isolation, and 46 strains were selected and characterized by means of biochemical tests and PCR. P. multocida strains were tested for capsular type, virulence genes, and resistance profile. A total of 45.6% (21/46 of isolates belonged to capsular type A, and 54.34% (25/46 of the isolates were untypeable. None of the strains harboured toxA or pfhA genes. The frequency of the other twenty genes tested was variable, and the data generated was used to build a dendrogram, showing the relatedness of strains, which were clustered according to origin. Resistance revealed to be more common against sulfonamides and cotrimoxazole, followed by erythromycin, penicillin, and amoxicillin.

  20. Differences in Extended-Spectrum Beta-Lactamase Producing Escherichia coli Virulence Factor Genes in the Baltic Sea Region

    OpenAIRE

    Jana Lillo; Kristiine Pai; Arta Balode; Mariia Makarova; Kristi Huik; Siiri Kõljalg; Marina Ivanova; Lidia Kaftyreva; Jolanta Miciuleviciene; Paul Naaber; Kristel Parv; Anastasia Pavelkovich; Tiiu Rööp; Karolin Toompere; Ludmila Suzhaeva

    2014-01-01

    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...

  1. 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.

  2. MvirDB—a microbial database of protein toxins, virulence factors and antibiotic resistance genes for bio-defence applications

    OpenAIRE

    Zhou, C. E.; Smith,J; Lam, M.; Zemla, A.; Dyer, M. D.; Slezak, T.

    2006-01-01

    Knowledge of toxins, virulence factors and antibiotic resistance genes is essential for bio-defense applications aimed at identifying ‘functional’ signatures for characterizing emerging or engineered pathogens. Whereas genetic signatures identify a pathogen, functional signatures identify what a pathogen is capable of. To facilitate rapid identification of sequences and characterization of genes for signature discovery, we have collected all publicly available (as of this writing), organized ...

  3. Research progress on virulence-related genes of Mycobacterium tuberculosis%结核分枝杆菌相关毒力基因的研究进展

    Institute of Scientific and Technical Information of China (English)

    丁珍珍; 杜先智

    2010-01-01

    Virulence plays an important role in tuberculosis, because only virulent strians can be pathogenic. Virulence of Mycobacterium tuberculosis means the ability to cause tuberculosis, and the pathogenicity is also associated with virulent factors. Mycobacterium tuberculosis is a typical intracellular pathogen,but only virulent strains can survive and reproduce intracellularly. Virulent factors play a key role in the proliferation of virulent strain macrophage. At present,little is known about the mechanisms of virulence-relaetd genes and virulent factors. This review summarizes several virulence-relaetd genes which are researched extensively.%在结核病的发生过程中,毒力起着重要的作用,因为只有毒力菌株才可致病.结核菌的毒力可以理解为其引起结核病的能力,而致病性与毒力因子总是联系在一起的.结核菌是典型的胞内寄生菌,但只有有毒株才能在细胞内存活和繁殖.毒力因子在毒力株的巨噬细胞复制中起关键作用,目前对毒力相关基因及毒力因子作用机制知之甚少.本文将对几个研究较多的毒力相关基因作一综述.

  4. Effects of partial deletion of the wzm and wzt genes on lipopolysaccharide synthesis and virulence of Brucella abortus S19.

    Science.gov (United States)

    Wang, Xiuran; Wang, Lin; Lu, Tiancheng; Yang, Yanling; Chen, Si; Zhang, Rui; Lang, Xulong; Yan, Guangmou; Qian, Jing; Wang, Xiaoxu; Meng, Lingyi; Wang, Xinglong

    2014-06-01

    Brucellosis is a worldwide human and animal infectious disease, and the effective methods of its control are immunisation of animals by vaccination and elimination. Brucella abortus S19 is one of the popular vaccines with virulence in the control of cattle Brucellosis. In the present study, allelic exchange plasmids of wzm and wzt genes and partial knockout mutants of wzm and wzt were constructed to evaluate the resulting difference in virulence of B. abortus S19. PCR analysis revealed that the target genes were knocked out. The mutants were rough mutants and they could be differentiated from natural infection by the Rose Bengal plate and standard agglutination tests. The molecular weights of lipopolysaccharides of the Δwzm and Δwzt mutants were clustered between 25 and 40 kDa, and 30 and 35 kDa separately, and were markedly different from those in B. abortus S19. The virulence of B. abortus Δwzm and Δwzt was decreased compared with that of B. abortus S19 in mice. All these results identified that there were several differences between the wzm and wzt genes on lipopolysaccharide synthesis and on the virulence of B. abortus. PMID:24718931

  5. A new experimental approach for studying bacterial genomic island evolution identifies island genes with bacterial host-specific expression patterns

    OpenAIRE

    Nickerson Cheryl A; Wilson James W

    2006-01-01

    Abstract Background Genomic islands are regions of bacterial genomes that have been acquired by horizontal transfer and often contain blocks of genes that function together for specific processes. Recently, it has become clear that the impact of genomic islands on the evolution of different bacterial species is significant and represents a major force in establishing bacterial genomic variation. However, the study of genomic island evolution has been mostly performed at the sequence level usi...

  6. Concurrent genotyping of Helicobacter pylori virulence genes and human cytokine SNP sites using whole genome amplified DNA derived from minute amounts of gastric biopsy specimen DNA

    Directory of Open Access Journals (Sweden)

    Borch Kurt

    2008-10-01

    Full Text Available Abstract Background Bacterial and cellular genotyping is becoming increasingly important in the diagnosis of infectious diseases. However, difficulties in obtaining sufficient amount of bacterial and cellular DNA extracted from the same human biopsy specimens is often a limiting factor. In this study, total DNA (host and bacterial DNA was isolated from minute amounts of gastric biopsy specimens and amplified by means of whole genome amplification using the multiple displacement amplification (MDA technique. Subsequently, MDA-DNA was used for concurrent Helicobacter pylori and human host cellular DNA genotyping analysis using PCR-based methods. Results Total DNA was isolated from gastric biopsy specimens of 12 subjects with gastritis and 16 control subjects having a normal mucosa. The DNA was amplified using a multiple displacement amplification (MDA kit. Next, concurrent genotyping was performed using H. pylori-specific virulence gene PCR amplification assays, pyrosequencing of bacterial 16S rDNA and PCR characterisation of various host genes. This includes Interleukin 1-beta (IL1B and Interferon-gamma receptor (IFNGR1 SNP analysis, and Interleukin-1 receptor antagonist (IL1RN variable tandem repeats (VNTR in intron 2. Finally, regions of the vacA-gene were PCR amplified using M13-sequence tagged primers which allowed for direct DNA sequencing, omitting cloning of PCR amplicons. H. pylori specific multiplex PCR assays revealed the presence of H. pylori cagA and vacA genotypic variations in 11 of 12 gastritis biopsy specimens. Using pyrosequencing, 16S rDNA variable V3 region signatures of H. pylori were found in 11 of 12 individuals with gastritis, but in none of the control subjects. Similarly, IL1B and IFNGR1-SNP and IL1RN-VNTR patterns could be established in all individuals. Furthermore, sequencing of M13-sequence tagged vacA-PCR amplicons revealed the presence of highly diverse H. pylori vacA-s/i/m regions. Conclusion The PCR

  7. Role of the LysR-type transcriptional regulator PecT and DNA supercoiling in the thermoregulation of pel genes, the major virulence factors in Dickeya dadantii.

    Science.gov (United States)

    Hérault, Elodie; Reverchon, Sylvie; Nasser, William

    2014-03-01

    Bacteria are colonizers of various environments and host organisms, and they are often subjected to drastic temperature variations. Dickeya dadantii is a pathogen infecting a wide range of plant species. Soft rot, the visible symptom, is mainly due to the production of pectate lyases (Pels) that destroy plant cell walls. The production of Pels is controlled by a complex regulation system that responds to various stimuli, such as the presence of pectin, growth phase and temperature. Despite numerous regulatory studies, the thermoregulation mechanism of Pel production remains unexplained. Here, we show that PecT, a previously identified repressor, modulates pel gene expression in a temperature-dependent manner, and we demonstrate that PecT binding on pel promoters increases concomitantly with temperature. High temperatures relax the DNA in D. dadantii, and remarkably, artificial relaxation of DNA at low temperatures increases PecT binding to DNA. Deletion of pecT augmented the capacity of D. dadantii to initiate soft-rot symptoms at high temperatures. These results reveal that DNA topology and PecT act in concert to fine-tune D. dadantii virulence in response to temperature. This novel combination between DNA topology and a conventional transcriptional regulator extends our understanding of the thermoregulation mechanisms involved in bacterial virulence. PMID:23869858

  8. Bacterial metal resistance genes and metal bioavailability in contaminated sediments

    International Nuclear Information System (INIS)

    In bacteria a metal may be defined as bioavailable if it crosses the cytoplasmic membrane to reach the cytoplasm. Once inside the cell, specific metal resistance systems may be triggered. In this research, specific metal resistance genes were used to estimate metal bioavailability in sediment microbial communities. Gene levels were measured by quantitative PCR and correlated to metals in sediments using five different protocols to estimate dissolved, particle-adsorbed and occluded metals. The best correlations were obtained with czcA (a Cd/Zn/Co efflux pump) and Cd/Zn adsorbed or occluded in particles. Only adsorbed Co was correlated to czcA levels. We concluded that the measurement of czcA gene levels by quantitative PCR is a promising tool which may complement the classical approaches used to estimate Cd/Zn/Co bioavailability in sediment compartments. - Highlights: • Metal resistance genes were used to estimate metal bioavailability in sediments. • Gene levels were correlated to metals using 5 different metal extraction protocols. • CzcA gene levels determined by quantitative PCR is a promising tool for Cd/Zn/Co. - Capsule Bacterial czcA is a potential biomarker of Cd, Zn and Co bioavailability in aquatic sediments as shown by quantitative PCR and sequential metal extraction

  9. Performance of resistance gene pyramids to races of rice bacterial blight in Zhejiang Province

    Institute of Scientific and Technical Information of China (English)

    ZHENGKangle; ZHUANGJieyun; WANGHanrong

    1998-01-01

    The effect of gene pyramiding on resistance to bacterial blight (BB) in rice was evahlated among the IR24-based near isogenic lines conraining single resistance gene and gene pyramids containing two, three or lour resistancegenes (see table).

  10. Detection of Virulence Genes and Growth Potential in Listeria monocytogenes Strains Isolated from Ricotta Salata Cheese.

    Science.gov (United States)

    Coroneo, Valentina; Carraro, Valentina; Aissani, Nadhem; Sanna, Adriana; Ruggeri, Alessandra; Succa, Sara; Meloni, Barbara; Pinna, Antonella; Sanna, Clara

    2016-01-01

    Ricotta Salata is a traditional ripened and salted whey cheese made in Sardinia (Italy) from sheep's milk. This product is catalogued as ready-to-eat food (RTE) since it is not submitted to any further treatment before consumption. Thus, foodborne pathogens, such as Listeria monocytogenes, can represent a health risk for consumers. In September 2012, the FDA ordered the recall of several batches of Ricotta Salata imported from Italy linked to 22 cases of Listeriosis in the United States. This study was aimed at evaluating the presence and virulence properties of L. monocytogenes in 87 samples of Ricotta Salata produced in Sardinia. The ability of this product to support its growth under foreseen packing and storing conditions was also evaluated in 252 samples. Of the 87 samples 17.2% were positive for the presence of L. monocytogenes with an average concentration of 2.2 log10 cfu/g. All virulence-associated genes (prfA, rrn, hlyA, actA, inlA, inlB, iap, plcA, and plcB) were detected in only one isolated strain. The Ricotta Salata samples were artificially inoculated and growth potential (δ) was assessed over a period of 3 mo. The value of the growth potential was always >0.5 log10 cfu/g under foreseen packing and storing conditions. This study indicates that Ricotta Salata supports the L. monocytogenes growth to levels that may present a serious risk to public health, even while stored at refrigeration temperatures. PMID:26666835

  11. The majority of genes in the pathogenic Neisseria species are present in non-pathogenic Neisseria lactamica, including those designated as 'virulence genes'

    Directory of Open Access Journals (Sweden)

    Saunders Nigel J

    2006-05-01

    Full Text Available Abstract Background Neisseria meningitidis causes the life-threatening diseases meningococcal meningitis and meningococcal septicemia. Neisseria gonorrhoeae is closely related to the meningococcus, but is the cause of the very different infection, gonorrhea. A number of genes have been implicated in the virulence of these related yet distinct pathogens, but the genes that define and differentiate the species and their behaviours have not been established. Further, a related species, Neisseria lactamica is not associated with either type of infection in normally healthy people, and lives as a harmless commensal. We have determined which of the genes so far identified in the genome sequences of the pathogens are also present in this non-pathogenic related species. Results Thirteen unrelated strains of N. lactamica were investigated using comparative genome hybridization to the pan-Neisseria microarray-v2, which contains 2845 unique gene probes. The presence of 127 'virulence genes' was specifically addressed; of these 85 are present in N. lactamica. Of the remaining 42 'virulence genes' only 11 are present in all four of the sequenced pathogenic Neisseria. Conclusion Assessment of the complete dataset revealed that the vast majority of genes present in the pathogens are also present in N. lactamica. Of the 1,473 probes to genes shared by all four pathogenic genome sequences, 1,373 hybridize to N. lactamica. These shared genes cannot include genes that are necessary and sufficient for the virulence of the pathogens, since N. lactamica does not share this behaviour. This provides an essential context for the interpretation of gene complement studies of the pathogens.

  12. Selection of Reference Genes for Gene Expression Analysis in Nilaparvata lugens with Different Levels of Virulence on Rice by Quantitative Real-Time PCR

    Institute of Scientific and Technical Information of China (English)

    WANG Wei-xia; LAI Feng-xiang; LI Kai-long; FU Qiang

    2014-01-01

    The brown planthopperNilaparvata lugens Stål (Homoptera: Delphacidae) can cause hopperburn by feeding on rice and also can transmit the grassy stunt disease. Resistant rice varieties have been developed, but severalN. lugens strains can recover their virulence to these resistant rice varieties. In the present study, reference genes with stable expression levels inN. lugens populations showed different levels of virulence to susceptible and resistant rice varieties. The expression of six candidate reference genes inN. lugens feeding on susceptible and resistant rice varieties was analyzed. These genes were evaluated for their potential use in the analysis of differential gene expression. Polymerase chain reaction data was generated fromN. lugens, including two different treatments (resistant or susceptible rice) and three virulentN. lugens populations. Three software programs (BestKeeper, Normfinder and geNorm) were used to assess the candidate reference genes. Both geNorm and Normfinder identified the genes18S,β-ACT,β-TUB andα-TUB as the most stable reference genes. BestKeeper identifiedETIF1 as the optimal reference gene with the least overall variation, whereas18S andα-TUB were the second and third most stably expressed genes, respectively. Therefore, we concluded that the genes18S andα-TUB were the most suitable reference genes inN. lugens. These results will facilitate future transcript profiling studies onN. lugens populations that show variation in virulence levels on different rice varieties.

  13. Correlation between Group B Streptococcal Genotypes, Their Antimicrobial Resistance Profiles, and Virulence Genes among Pregnant Women in Lebanon

    Directory of Open Access Journals (Sweden)

    Antoine Hannoun

    2009-01-01

    Full Text Available The antimicrobial susceptibility profiles of 76 Streptococcus agalactiae (Group B Streptococci [GBS] isolates from vaginal specimens of pregnant women near term were correlated to their genotypes generated by Random Amplified Polymorphic DNA analysis and their virulence factors encoding genes cylE, lmb, scpB, rib, and bca by PCR. Based on the distribution of the susceptibility patterns, six profiles were generated. RAPD analysis detected 7 clusters of genotypes. The cylE gene was present in 99% of the isolates, the lmb in 96%, scpB in 94.7%, rib in 33%, and bca in 56.5% of isolates. The isolates demonstrated a significant correlation between antimicrobial resistance and genotype clusters denoting the distribution of particular clones with different antimicrobial resistance profiles, entailing the practice of caution in therapeutic options. All virulence factors encoding genes were detected in all seven genotypic clusters with rib and bca not coexisting in the same genome.

  14. Reciprocal interaction between dental alloy biocorrosion and Streptococcus mutans virulent gene expression.

    Science.gov (United States)

    Zhang, Songmei; Qiu, Jing; Ren, Yanfang; Yu, Weiqiang; Zhang, Fuqiang; Liu, Xiuxin

    2016-04-01

    Corrosion of dental alloys is a major concern in dental restorations. Streptococcus mutans reduces the pH in oral cavity and induces demineralization of the enamel as well as corrosion of restorative dental materials. The rough surfaces of dental alloys induced by corrosion enhance the subsequent accumulation of plaque. In this study, the corrosion process of nickel-chromium (Ni-Cr) and cobalt-chromium (Co-Cr) alloys in a nutrient-rich medium containing S. mutans was studied using inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray photoelectron spectroscopy (XPS) and electrochemical corrosion test. Our results showed that the release of Ni and Co ions increased, particularly after incubation for 3 days. The electrochemical corrosion results showed a significant decrease in the corrosion resistance (Rp) value after the alloys were immersed in the media containing S. mutans for 3 days. Correspondingly, XPS revealed a reduction in the relative dominance of Ni, Co, and Cr in the surface oxides after the alloys were immersed in the S. mutans culture. After removal of the biofilm, the pre-corroded alloys were re-incubated in S. mutans medium, and the expressions of genes associated with the adhesion and acidogenesis of S. mutans, including gtfBCD, gbpB, fif and ldh, were evaluated by detecting the mRNA levels using real-time reverse transcription polymerase chain reaction (RT-PCR). We found that the gtfBCD, gbpB, ftf and Idh expression of S. mutans were noticeably increased after incubation with pre-corroded alloys for 24 h. This study demonstrated that S. mutans enhanced the corrosion behavior of the dental alloys, on the other hand, the presence of corroded alloy surfaces up-regulated the virulent gene expression in S. mutans. Compared with smooth surfaces, the rough corroded surfaces of dental alloys accelerated the bacteria-adhesion and corrosion process by changing the virulence gene expression of S. mutans. PMID:26896953

  15. Cotransfer of antibiotic resistance genes and a hylEfm-containing virulence plasmid in Enterococcus faecium.

    Science.gov (United States)

    Arias, Cesar A; Panesso, Diana; Singh, Kavindra V; Rice, Louis B; Murray, Barbara E

    2009-10-01

    The hyl(Efm) gene (encoding a putative hyaluronidase) has been found almost exclusively in Enterococcus faecium clinical isolates, and recently, it was shown to be on a plasmid which increased the ability of E. faecium strains to colonize the gastrointestinal tract. In this work, the results of mating experiments between hyl(Efm)-containing strains of E. faecium belonging to clonal cluster 17 and isolated in the United States and Colombia indicated that the hyl(Efm) gene of these strains is also carried on large plasmids (>145 kb) which we showed transfer readily from clinical strains to E. faecium hosts. Cotransfer of resistance to vancomycin and high-level resistance (HLR) to aminoglycosides (gentamicin and streptomycin) and erythromycin was also observed. The vanA gene cluster and gentamicin resistance determinants were genetically linked to hyl(Efm), whereas erm(B) and ant(6)-I, conferring macrolide-lincosamide-streptogramin B resistance and HLR to streptomycin, respectively, were not. A hyl(Efm)-positive transconjugant resulting from a mating between a well-characterized endocarditis strain [TX0016 (DO)] and a derivative of a fecal strain of E. faecium from a healthy human volunteer (TX1330RF) exhibited increased virulence in a mouse peritonitis model. These results indicate that E. faecium strains use a strategy which involves the recruitment into the same genetic unit of antibiotic resistance genes and determinants that increase the ability to produce disease. Our findings indicate that the acquisition of the hyl(Efm) plasmids may explain, at least in part, the recent successful emergence of some E. faecium strains as nosocomial pathogens. PMID:19667280

  16. Virulence Plasmid of Rhodococcus equi Contains Inducible Gene Family Encoding Secreted Proteins

    OpenAIRE

    Byrne, Barbara A.; Prescott, John F.; Palmer, Guy H.; Takai, Shinji; Nicholson, Vivian M.; Alperin, Debra C.; Hines, Stephen A.

    2001-01-01

    Rhodococcus equi causes severe pyogranulomatous pneumonia in foals. This facultative intracellular pathogen produces similar lesions in immunocompromised humans, particularly in AIDS patients. Virulent strains of R. equi bear a large plasmid that is required for intracellular survival within macrophages and for virulence in foals and mice. Only two plasmid-encoded proteins have been described previously; a 15- to 17-kDa surface protein designated virulence-associated protein A (VapA) and an a...

  17. The co-evolved Helicobacter pylori and gastric cancer: trinity of bacterial virulence, host susceptibility and lifestyle

    Directory of Open Access Journals (Sweden)

    Devi S Manjulata

    2007-01-01

    Full Text Available Abstract Helicobacter pylori is an important yet unproven etiological agent of gastric cancer. H. pylori infection is more prevalent in developing Asian countries like India and it is usually acquired at an early age. It has been two decades since Marshall and Warren (1984 first described curved bacilli in the stomach of ulcer and gastritis patients. This discovery has won them the Nobel Prize recently, but the debate whether H. pylori is a pathogen or a commensal organism is still hot. Associations with disease-specific factors remain illusive years after the genome sequences were made available. Cytotoxin-associated antigen A (CagA and the so-called plasticity region cluster genes are implicated in pathogenesis of the carcinoma of stomach. Another virulence factor VacA whose role is still debatable, has recently been projected in pathology of gastric cancer. Studies of the evolution through genetic variation in H. pylori populations have provided a window into the history of human population migrations and a possible co-evolution of this pathogen with its human host. Possible symbiotic relationships were seriously debated since the discovery of this pathogen. The debate has been further intensified as some studies proposed H. pylori infection to be beneficial in some humans. In this commentary, we attempt to briefly discuss about H. pylori as a human pathogen, and some of the important issues linked to its pathophysiology in different hosts. 'We dance around in a ring and suppose, the secret sits in the middle and knows' – Robert Frost

  18. Molecular Analysis and Identification of Virulence Gene on pRST98 from Multi-Drug Resistant Salmonella typhi

    Institute of Scientific and Technical Information of China (English)

    Rui Huang; Shuyan Wu; Xueguang Zhang; Yanyun Zhang

    2005-01-01

    pRST98 is a large and conjugative resistant plasmid (R plasmid) of 98.6 mega-dalton from multi-drug resistant Salmonella typhi (S.typhi), which was classified to incompatibility group C (Inc C). It has been found that pRST98 made its host bacteria not only antibiotic resistant but also more virulent. In this study we explored the possibility of plasmid pRST98 in S. typhi carrying the Salmonella plasmid virulence gene -spv. The plasmid pRST98 was isolated,purified and then digested by nine restriction endonucleases to make the plasmid enzyme profile. Spv-specific PCR and Southern blot were applied to identify the virulence gene on pRST98. The amplified spv fragments spvR and spvB were cloned into pGEM-T EASY and then the DNA sequences were analysed. The fragments of pRST98 digested by endonucleases Bgl Ⅱ, Pst Ⅰ and Sac Ⅱ were identified, which may be useful for molecular analysis and further epidemiological surveillance of pRST98. The results of PCR and Southern blot showed that spv homologous genetic sequence which had been found in all pathogenesis Salmonella spp. except S. typhi was also presented on pRST98. The ORF of spvR and spvB of pRST98 were 894 bp and 1,776 bp, respectively. They have more than 99% homology with that of spvR and spvB on virulence plasmid in S. typhmurium. The genotype research on pRST98 revealed that there is a plasmid carrying genes responsible for drug resistance and virulence in S. typhi. This is the first report for such kind chimerical plasmid in S. typhi. Cellular & Molecular Immunology. 2005;2(2):136-140.

  19. Multiple gene sequence analysis using genes of the bacterial DNA repair pathway

    OpenAIRE

    Miguel Rotelok Neto; Carolina Weigert Galvão; Leonardo Magalhães Cruz; Dieval Guizelini; Leilane Caline Silva; Jarem Raul Garcia; Rafael Mazer Etto

    2015-01-01

    The ability to recognize and repair abnormal DNA structures is common to all forms of life. Physiological studies and genomic sequencing of a variety of bacterial species have identified an incredible diversity of DNA repair pathways. Despite the amount of available genes in public database, the usual method to place genomes in a taxonomic context is based mainly on the 16S rRNA or housekeeping genes. Thus, the relationships among genomes remain poorly understood. In this work, an approach of...

  20. Glycosylation defects and virulence phenotypes of Leishmania mexicana phosphomannomutase and dolicholphosphate-mannose synthase gene deletion mutants.

    Science.gov (United States)

    Garami, A; Mehlert, A; Ilg, T

    2001-12-01

    Leishmania parasites synthesize an abundance of mannose (Man)-containing glycoconjugates thought to be essential for virulence to the mammalian host and for viability. These glycoconjugates include lipophosphoglycan (LPG), proteophosphoglycans (PPGs), glycosylphosphatidylinositol (GPI)-anchored proteins, glycoinositolphospholipids (GIPLs), and N-glycans. A prerequisite for their biosynthesis is an ample supply of the Man donors GDP-Man and dolicholphosphate-Man. We have cloned from Leishmania mexicana the gene encoding the enzyme phosphomannomutase (PMM) and the previously described dolicholphosphate-Man synthase gene (DPMS) that are involved in Man activation. Surprisingly, gene deletion experiments resulted in viable parasite lines lacking the respective open reading frames (DeltaPMM and DeltaDPMS), a result against expectation and in contrast to the lethal phenotype observed in gene deletion experiments with fungi. L. mexicana DeltaDPMS exhibits a selective defect in LPG, protein GPI anchor, and GIPL biosynthesis, but despite the absence of these structures, which have been implicated in parasite virulence and viability, the mutant remains infectious to macrophages and mice. By contrast, L. mexicana DeltaPMM are largely devoid of all known Man-containing glycoconjugates and are unable to establish an infection in mouse macrophages or the living animal. Our results define Man activation leading to GDP-Man as a virulence pathway in Leishmania. PMID:11689705

  1. Neither gastric topological distribution nor principle virulence genes of Helicobacterpylori contributes to clinical outcomes

    Institute of Scientific and Technical Information of China (English)

    Yan Wing Ho; Khek Yu Ho; Felipe Ascencio; Bow Ho

    2004-01-01

    AIM: Studies on Helicobacter pylori(Hpylori) and gastroduodenal diseases have focused mainly on the distal sites of the stomach, but relationship with the gastric cardia is lacking. The aim of this study is to determine if the gastric topology and genotypic distribution of H pylori were associated with different upper gastrointestinal pathologies in a multiethnic Asian population.METHODS: Gastric biopsies from the cardia, body/corpus and antrum were endoscoped from a total of 155 patients with dyspepsia and/or reflux symptoms, with informed consent. H pylori isolates obtained were tested for the presence of 26kDa, ureC, cagA, vacA, iceA1, iceA2 and babA2 genes using PCR while DNA fingerprints were generated using random amplification polymorphic DNA(RAPD).RESULTS: H pyloriwas present in 51/155 (33%) of patients studied. Of these, 16, 15 and 20 were isolated from patients with peptic ulcer diseases, gastroesophageal reflux diseases and non-ulcer dyspepsia, respectively. Of the H pylori positive patients, 75% (38/51) had H pylori in all three gastric sites.The prevalence of various genes in the H pylori isolates was shown to be similar irrespective of their colonization sites as well as among the same site of different patients.The RAPD profiles of H pylori isolates from different gastric sites were highly similar among intra-patients but varied greatly between different patients.CONCLUSION: Topographic colonization of H pylori and the virulence genes harboured by these isolates have no direct bearing to the clinical state of the patients. In multiethnic Singapore, the stomach of each patient is colonized by a predominant strain of H pylori, irrespective of the clinical diagnosis.

  2. A Nonluminescent and Highly Virulent Vibrio harveyi Strain Is Associated with “Bacterial White Tail Disease” of Litopenaeus vannamei Shrimp

    Science.gov (United States)

    Zhou, Junfang; Fang, Wenhong; Yang, Xianle; Zhou, Shuai; Hu, Linlin; Li, Xincang; Qi, Xinyong; Su, Hang; Xie, Layue

    2012-01-01

    Recurrent outbreaks of a disease in pond-cultured juvenile and subadult Litopenaeus vannamei shrimp in several districts in China remain an important problem in recent years. The disease was characterized by “white tail” and generally accompanied by mass mortalities. Based on data from the microscopical analyses, PCR detection and 16S rRNA sequencing, a new Vibrio harveyi strain (designated as strain HLB0905) was identified as the etiologic pathogen. The bacterial isolation and challenge tests demonstrated that the HLB0905 strain was nonluminescent but highly virulent. It could cause mass mortality in affected shrimp during a short time period with a low dose of infection. Meanwhile, the histopathological and electron microscopical analysis both showed that the HLB0905 strain could cause severe fiber cell damages and striated muscle necrosis by accumulating in the tail muscle of L. vannamei shrimp, which led the affected shrimp to exhibit white or opaque lesions in the tail. The typical sign was closely similar to that caused by infectious myonecrosis (IMN), white tail disease (WTD) or penaeid white tail disease (PWTD). To differentiate from such diseases as with a sign of “white tail” but of non-bacterial origin, the present disease was named as “bacterial white tail disease (BWTD)”. Present study revealed that, just like IMN and WTD, BWTD could also cause mass mortalities in pond-cultured shrimp. These results suggested that some bacterial strains are changing themselves from secondary to primary pathogens by enhancing their virulence in current shrimp aquaculture system. PMID:22383954

  3. Virulence of wheat yellow rust races and resistance genes of wheat cultivars in Ecuador

    NARCIS (Netherlands)

    Ochoa, J.B.; Danial, D.L.; Paucar, B.

    2007-01-01

    Virulence factors of the yellow rust, Puccinia striiformis, populations in bread wheat were studied in Ecuador between 1973 and 2004. The number of virulence factors has increased markedly from very few in the early seventies to 16 at the end of the 90s. Isolates belonging to race 0E0 seem to be the

  4. The adenylate cyclase gene MaAC is required for virulence and multi-stress tolerance of Metarhizium acridum

    Directory of Open Access Journals (Sweden)

    Liu Shuyang

    2012-08-01

    Full Text Available Abstract Background The efficacy of entomopathogenic fungi in pest control is mainly affected by various adverse environmental factors, such as heat shock and UV-B radiation, and by responses of the host insect, such as oxidative stress, osmotic stress and fever. In this study, an adenylate cyclase gene (MaAC was cloned from the locust-specific entomopathogenic fungus, Metarhizium acridum, which is homologous to various fungal adenylate cyclase genes. RNA silencing was adapted to analyze the role of MaAC in virulence and tolerance to adverse environmental and host insect factors. Results Compared with the wild type, the vegetative growth of the RNAi mutant was decreased in PD (potato dextrose medium, Czapek-dox and PDA plates, respectively, demonstrating that MaAC affected vegetative growth. The cAMP levels were also reduced in PD liquid culture, and exogenous cAMP restored the growth of RNAi mutants. These findings suggested that MaAC is involved in cAMP synthesis. The knockdown of MaAC by RNAi led to a reduction in virulence after injection or topical inoculation. Furthermore, the RNAi mutant grew much slower than the wild type in the haemolymph of locust in vitro and in vivo, thus demonstrating that MaAC affects the virulence of M. acridum via fungal growth inside the host locust. A plate assay indicated that the tolerances of the MaAC RNAi mutant under oxidative stress, osmotic stress, heat shock and UV-B radiation was decreased compared with the wild type. Conclusion MaAC is required for virulence and tolerance to oxidative stress, osmotic stress, heat shock and UV-B radiation. MaAC affects fungal virulence via vegetative growth inside the insect and tolerance against oxidative stress, osmotic stress and locust fever.

  5. Virulence and resistance gene profiles of staphylococcus aureus strains isolated from ready-to-eat foods.

    Science.gov (United States)

    Baumgartner, Andreas; Niederhauser, Isabel; Johler, Sophia

    2014-07-01

    Staphylococcal food poisoning represents the most prevalent foodborne intoxication worldwide. Oral intake of staphylococcal enterotoxins from food can result in emesis and diarrhea and can be fatal in children and the elderly. Few data have been available on the characteristics and sources of Staphylococcus aureus strains isolated from ready-to-eat (RTE) foods. In this study, we used a DNA microarray to determine virulence and antimicrobial resistance gene profiles of S. aureus from RTE foods. A total of 267 S. aureus strains isolated from 244 RTE foods were investigated. The isolates originated from precooked foods (41% of isolates), meat and fish products (17%), cheese (13%), delicatessen salads (8%), sandwiches and canapés (8%), confectionery and bakery products (6%), and various other RTE foods (7%). Eleven samples (5%), of which 9 were raw milk cheeses, contained > 10(5) CFU/g, which is considered a health risk. Four S. aureus strains were associated with intoxications; three cases were linked to consumption of cheese and one case was linked to consumption of potato salad. DNA microarray results revealed that one-third of the tested strains had at least one major enterotoxin gene (sea through see). We also detected the toxic shock syndrome gene (18% of isolates) and various genes conferring antimicrobial resistance, including genes involved in resistance to beta-lactams (blaZ, 72% of isolates), methicillin (mecA, 1% of isolates), and vancomycin (vanB, 1% of isolates). S. aureus strains were most frequently assigned to clonal complex (CC) 30 (17% of isolates), CC8 (12%), CC15 (11%), and CC45 (10%), which are commonly detected in humans colonized or infected with S. aureus. Although a large proportion of the tested food items contained milk, we did not detect CC705, the most prevalent clonal complex among S. aureus isolates from bovine mastitis milk. Our results suggest that S. aureus isolates from RTE foods do not commonly originate from animals but more

  6. Investigate the frequency of virulence genes Vibrio parahaemolyticus isolated from fish, lobsters and crabs caught from Persian Gulf

    OpenAIRE

    Farhad Safarpourdehkordi; Sahar Hosseini; Ebrahim Rahimi; Manouchehr Momeni; Emad Yahaghi; Ebrahim Khodaverdi Darian

    2014-01-01

    Background and Aim: Annually, many reports of occurrence of food poisoning due to the consumption of sea-foods contaminated with Vibrio species have been published. The present study was carried out to study the prevalence rate of Vibrio parahaemolyticus and V. cholera and evaluation of presence of virulence genes of V. parahaemolyticus in sea-food products caught from Persian Gulf. Materials and Methods: In total, 200 samples of fish, lobster and crab caught from Persian Gulf collected in...

  7. Identification of Residues Responsible for the Defective Virulence Gene Regulator Mga Produced by a Natural Mutant of Streptococcus pyogenes

    OpenAIRE

    Vahling, Cheryl M.; McIver, Kevin S.

    2005-01-01

    Mga is a transcriptional regulator in the pathogen Streptococcus pyogenes that positively activates several important virulence genes involved in colonization and immune evasion in the human host. A naturally occurring mutant of Mga that is defective in its ability to activate transcription has been identified in the serotype M50 strain B514-Sm. Sequence alignment of the defective M50 Mga with the fully functional Mga from serotypes M4 and M49 revealed only three amino acid changes that might...

  8. Identification of New Genes Involved in the Virulence of Listeria monocytogenes by Signature-Tagged Transposon Mutagenesis

    OpenAIRE

    Autret, Nicolas; Dubail, Iharilalao; Trieu-Cuot, Patrick; Berche, Patrick; Charbit, Alain

    2001-01-01

    Listeria monocytogenes is a gram-positive, facultative intracellular pathogen that can cause severe food-born infections in humans and animals. We have adapted signature-tagged transposon mutagenesis to L. monocytogenes to identify new genes involved in virulence in the murine model of infection. We used transposon Tn1545 carried on the integrative vector pAT113. Forty-eight tagged transposons were constructed and used to generate banks of L. monocytogenes mutants. Pools of 48 mutants were as...

  9. Virulence Genes and Neutral DNA Markers of Helicobacter pylori Isolates from Different Ethnic Communities of West Bengal, India

    OpenAIRE

    Datta, Simanti; Chattopadhyay, Santanu; G. Balakrish Nair; Mukhopadhyay, Asish K.; Hembram, Jabaranjan; Berg, Douglas E.; Rani Saha, Dhira; Khan, Asis; Santra, Amal; S.K. Bhattacharya; Chowdhury, Abhijit

    2003-01-01

    Virulence-associated genes and neutral DNA markers of Helicobacter pylori strains from the Santhal and Oroan ethnic minorities of West Bengal, India, were studied. These people have traditionally been quite separate from other Indians and differ culturally, genetically, and linguistically from mainstream Bengalis, whose H. pylori strains have been characterized previously. H. pylori was found in each of 49 study participants, although none had peptic ulcer disease, and was cultured from 31 of...

  10. Aberrant host immune response induced by highly virulent PRRSV identified by digital gene expression tag profiling

    Directory of Open Access Journals (Sweden)

    Zhao Xiao

    2010-10-01

    Full Text Available Abstract Background There was a large scale outbreak of the highly pathogenic porcine reproductive and respiratory syndrome (PRRS in China and Vietnam during 2006 and 2007 that resulted in unusually high morbidity and mortality among pigs of all ages. The mechanisms underlying the molecular pathogenesis of the highly virulent PRRS virus (H-PRRSV remains unknown. Therefore, the relationship between pulmonary gene expression profiles after H-PRRSV infection and infection pathology were analyzed in this study using high-throughput deep sequencing and histopathology. Results H-PRRSV infection resulted in severe lung pathology. The results indicate that aberrant host innate immune responses to H-PRRSV and induction of an anti-apoptotic state could be responsible for the aggressive replication and dissemination of H-PRRSV. Prolific rapid replication of H-PRRSV could have triggered aberrant sustained expression of pro-inflammatory cytokines and chemokines leading to a markedly robust inflammatory response compounded by significant cell death and increased oxidative damage. The end result was severe tissue damage and high pathogenicity. Conclusions The systems analysis utilized in this study provides a comprehensive basis for better understanding the pathogenesis of H-PRRSV. Furthermore, it allows the genetic components involved in H-PRRSV resistance/susceptibility in swine populations to be identified.

  11. Highly frequent mutations in negative regulators of multiple virulence genes in group A streptococcal toxic shock syndrome isolates.

    Science.gov (United States)

    Ikebe, Tadayoshi; Ato, Manabu; Matsumura, Takayuki; Hasegawa, Hideki; Sata, Tetsutaro; Kobayashi, Kazuo; Watanabe, Haruo

    2010-04-01

    Streptococcal toxic shock syndrome (STSS) is a severe invasive infection characterized by the sudden onset of shock and multiorgan failure; it has a high mortality rate. Although a number of studies have attempted to determine the crucial factors behind the onset of STSS, the responsible genes in group A Streptococcus have not been clarified. We previously reported that mutations of csrS/csrR genes, a two-component negative regulator system for multiple virulence genes of Streptococcus pyogenes, are found among the isolates from STSS patients. In the present study, mutations of another negative regulator, rgg, were also found in clinical isolates of STSS patients. The rgg mutants from STSS clinical isolates enhanced lethality and impaired various organs in the mouse models, similar to the csrS mutants, and precluded their being killed by human neutrophils, mainly due to an overproduction of SLO. When we assessed the mutation frequency of csrS, csrR, and rgg genes among S. pyogenes isolates from STSS (164 isolates) and non-invasive infections (59 isolates), 57.3% of the STSS isolates had mutations of one or more genes among three genes, while isolates from patients with non-invasive disease had significantly fewer mutations in these genes (1.7%). The results of the present study suggest that mutations in the negative regulators csrS/csrR and rgg of S. pyogenes are crucial factors in the pathogenesis of STSS, as they lead to the overproduction of multiple virulence factors. PMID:20368967

  12. Influenza A virus NS1 gene mutations F103L and M106I increase replication and virulence

    Directory of Open Access Journals (Sweden)

    Ping Jihui

    2011-01-01

    Full Text Available Abstract Background To understand the evolutionary steps required for a virus to become virulent in a new host, a human influenza A virus (IAV, A/Hong Kong/1/68(H3N2 (HK-wt, was adapted to increased virulence in the mouse. Among eleven mutations selected in the NS1 gene, two mutations F103L and M106I had been previously detected in the highly virulent human H5N1 isolate, A/HK/156/97, suggesting a role for these mutations in virulence in mice and humans. Results To determine the selective advantage of these mutations, reverse genetics was used to rescue viruses containing each of the NS1 mouse adapted mutations into viruses possessing the HK-wt NS1 gene on the A/PR/8/34 genetic backbone. Both F103L and M106I NS1 mutations significantly enhanced growth in vitro (mouse and canine cells and in vivo (BALB/c mouse lungs as well as enhanced virulence in the mouse. Only the M106I NS1 mutation enhanced growth in human cells. Furthermore, these NS1 mutations enhanced early viral protein synthesis in MDCK cells and showed an increased ability to replicate in mouse interferon β (IFN-β pre-treated mouse cells relative to rPR8-HK-NS-wt NS1. The double mutant, rPR8-HK-NS-F103L + M106I, demonstrated growth attenuation late in infection due to increased IFN-β induction in mouse cells. We then generated a rPR8 virus possessing the A/HK/156/97 NS gene that possesses 103L + 106I, and then rescued the L103F + I106M mutant. The 103L + 106I mutations increased virulence by >10 fold in BALB/c mice. We also inserted the avian A/Ck/Beijing/1/95 NS1 gene (the source lineage of the A/HK/156/97 NS1 gene that possesses 103L + 106I, onto the A/WSN/33 backbone and then generated the L103F + I106M mutant. None of the H5N1 and H9N2 NS containing viruses resulted in increased IFN-β induction. The rWSN-A/Ck/Beijing/1/95-NS1 gene possessing 103L and 106I demonstrated 100 fold enhanced growth and >10 fold enhanced virulence that was associated with increased tropism for lung

  13. Indole and 7-benzyloxyindole attenuate the virulence of Staphylococcus aureus.

    Science.gov (United States)

    Lee, Jin-Hyung; Cho, Hyun Seob; Kim, Younghoon; Kim, Jung-Ae; Banskota, Suhrid; Cho, Moo Hwan; Lee, Jintae

    2013-05-01

    Human pathogens can readily develop drug resistance due to the long-term use of antibiotics that mostly inhibit bacterial growth. Unlike antibiotics, antivirulence compounds diminish bacterial virulence without affecting cell viability and thus, may not lead to drug resistance. Staphylococcus aureus is a major agent of nosocomial infections and produces diverse virulence factors, such as the yellow carotenoid staphyloxanthin, which promotes resistance to reactive oxygen species (ROS) and the host immune system. To identify novel antivirulence compounds, bacterial signal indole present in animal gut and diverse indole derivatives were investigated with respect to reducing staphyloxanthin production and the hemolytic activity of S. aureus. Treatment with indole or its derivative 7-benzyloxyindole (7BOI) caused S. aureus to become colorless and inhibited its hemolytic ability without affecting bacterial growth. As a result, S. aureus was more easily killed by hydrogen peroxide (H₂O₂) and by human whole blood in the presence of indole or 7BOI. In addition, 7BOI attenuated S. aureus virulence in an in vivo model of nematode Caenorhabditis elegans, which is readily infected and killed by S. aureus. Transcriptional analyses showed that both indole and 7BOI repressed the expressions of several virulence genes such as α-hemolysin gene hla, enterotoxin seb, and the protease genes splA and sspA and modulated the expressions of the important regulatory genes agrA and sarA. These findings show that indole derivatives are potential candidates for use in antivirulence strategies against persistent S. aureus infection. PMID:23318836

  14. cDNA Array Analysis of the Differential Expression Change in Virulence-related Genes During the Development of Resistance in Candida albicans

    Institute of Scientific and Technical Information of China (English)

    Zheng XU; Yuan-Ying JIANG; Yong-Bing CAO; Jun-Dong ZHANG; Ying-Ying CAO; Ping-Hui GAO; De-Jun WANG; Xu-Ping FU; Kang YING; Wan-Sheng CHEN

    2005-01-01

    Candida albicans is the most frequently isolated fungus in immunocompromised patients associated with mucosal and deep-tissue infections. To investigate the correlation between virulence and resistance on a gene expression profile in C. albicans, we examined the changes in virulence-related genes during the development of resistance in C. albicans from bone marrow transplant patients using a constructed cDNA array representing 3096 unigenes. In addition to the genes known to be associated with azole resistance,16 virulence-related genes were identified, whose differential expressions were newly found to be associated with the resistant phenotype. Differential expressions for these genes were confirmed by RT-PCR independently. Furthermore, the up-regulation of EFG1, CPH2, TEC1, CDC24, SAP10, ALS9, SNF1, SPO72 and BDF1, and the down-regulation of RAD32, IPF3636 and UBI4 resulted in stronger virulence and invasiveness in the resistant isolates compared with susceptible ones. These findings provide a link between the expression of virulence genes and development of resistance during C. albicans infection in bone marrow transplant (BMT) patients, where C. albicans induces hyphal formation and expression change in multiple virulence factors.

  15. Virulence Plasmid-Borne spvB and spvC Genes Can Replace the 90-Kilobase Plasmid in Conferring Virulence to Salmonella enterica Serovar Typhimurium in Subcutaneously Inoculated Mice

    OpenAIRE

    Matsui, Hidenori; Bacot, Christopher M.; Garlington, Wendy A.; Doyle, Thomas J.; ROBERTS, Steve; Gulig, Paul A.

    2001-01-01

    In a mouse model of systemic infection, the spv genes carried on the Salmonella enterica serovar Typhimurium virulence plasmid increase the replication rate of salmonellae in host cells of the reticuloendothelial system, most likely within macrophages. A nonpolar deletion in the spvB gene greatly decreased virulence but could not be complemented by spvB alone. However, a low-copy-number plasmid expressing spvBC from a constitutive lacUV5 promoter did complement the spvB deletion. By examining...

  16. The Hos2 Histone Deacetylase Controls Ustilago maydis Virulence through Direct Regulation of Mating-Type Genes.

    Directory of Open Access Journals (Sweden)

    Alberto Elías-Villalobos

    2015-08-01

    Full Text Available Morphological changes are critical for host colonisation in plant pathogenic fungi. These changes occur at specific stages of their pathogenic cycle in response to environmental signals and are mediated by transcription factors, which act as master regulators. Histone deacetylases (HDACs play crucial roles in regulating gene expression, for example by locally modulating the accessibility of chromatin to transcriptional regulators. It has been reported that HDACs play important roles in the virulence of plant fungi. However, the specific environment-sensing pathways that control fungal virulence via HDACs remain poorly characterised. Here we address this question using the maize pathogen Ustilago maydis. We find that the HDAC Hos2 is required for the dimorphic switch and pathogenic development in U. maydis. The deletion of hos2 abolishes the cAMP-dependent expression of mating type genes. Moreover, ChIP experiments detect Hos2 binding to the gene bodies of mating-type genes, which increases in proportion to their expression level following cAMP addition. These observations suggest that Hos2 acts as a downstream component of the cAMP-PKA pathway to control the expression of mating-type genes. Interestingly, we found that Clr3, another HDAC present in U. maydis, also contributes to the cAMP-dependent regulation of mating-type gene expression, demonstrating that Hos2 is not the only HDAC involved in this control system. Overall, our results provide new insights into the role of HDACs in fungal phytopathogenesis.

  17. Genes that encodes NAGT, MIF1 and MIF2 are not virulence factors for kala-azar caused by Leishmania infantum

    Directory of Open Access Journals (Sweden)

    Bruno Guedes Alcoforado Aguiar

    2014-10-01

    Full Text Available Introduction Kala-azar is a disease resulting from infection by Leishmania donovani and Leishmania infantum. Most patients with the disease exhibit prolonged fever, wasting, anemia and hepatosplenomegaly without complications. However, some patients develop severe disease with hemorrhagic manifestations, bacterial infections, jaundice, and edema dyspnea, among other symptoms, followed by death. Among the parasite molecules that might influence the disease severity are the macrophage migration inhibitory factor-like proteins (MIF1 and MIF2 and N-acetylglucosamine-1-phosphotransferase (NAGT, which act in the first step of protein N-glycosylation. This study aimed to determine whether MIF1, MIF2 and NAGT are virulence factors for severe kala-azar. Methods To determine the parasite genotype in kala-azar patients from Northeastern Brazil, we sequenced the NAGT genes of L. infantum from 68 patients as well as the MIF1 and MIF2 genes from 76 different subjects with diverse clinical manifestations. After polymerase chain reaction (PCR, the fragments were sequenced, followed by polymorphism identification. Results The nucleotide sequencing of the 144 amplicons revealed the absence of genetic variability of the NAGT, MIF1 and MIF2 genes between the isolates. The conservation of these genes suggests that the clinical variability of kala-azar does not depend upon these genes. Additionally, this conservation suggests that these genes may be critical for parasite survival. Conclusions NAGT, MIF1 and MIF2 do not alter the severity of kala-azar. NAGT, MIF1 and MIF2 are highly conserved among different isolates of identical species and exhibit potential for use in phylogenetic inferences or molecular diagnosis.

  18. Detecting rare gene transfer events in bacterial populations

    Directory of Open Access Journals (Sweden)

    Kaare Magne Nielsen

    2014-01-01

    Full Text Available Horizontal gene transfer (HGT enables bacteria to access, share, and recombine genetic variation, resulting in genetic diversity that cannot be obtained through mutational processes alone. In most cases, the observation of evolutionary successful HGT events relies on the outcome of initially rare events that lead to novel functions in the new host, and that exhibit a positive effect on host fitness. Conversely, the large majority of HGT events occurring in bacterial populations will go undetected due to lack of replication success of transformants. Moreover, other HGT events that would be highly beneficial to new hosts can fail to ensue due to lack of physical proximity to the donor organism, lack of a suitable gene transfer mechanism, genetic compatibility, and stochasticity in tempo-spatial occurrence. Experimental attempts to detect HGT events in bacterial populations have typically focused on the transformed cells or their immediate offspring. However, rare HGT events occurring in large and structured populations are unlikely to reach relative population sizes that will allow their immediate identification; the exception being the unusually strong positive selection conferred by antibiotics. Most HGT events are not expected to alter the likelihood of host survival to such an extreme extent, and will confer only minor changes in host fitness. Due to the large population sizes of bacteria and the time scales involved, the process and outcome of HGT are often not amenable to experimental investigation. Population genetic modeling of the growth dynamics of bacteria with differing HGT rates and resulting fitness changes is therefore necessary to guide sampling design and predict realistic time frames for detection of HGT, as it occurs in laboratory or natural settings. Here we review the key population genetic parameters, consider their complexity and highlight knowledge gaps for further research.

  19. A gene from Renibacterium salmoninarum encoding a product which shows homology to bacterial zinc-metalloproteases.

    Science.gov (United States)

    Grayson, T H; Evenden, A J; Gilpin, M L; Martin, K L; Munn, C B

    1995-06-01

    A genomic library constructed from Renibacterium salmoninarum isolate MT444 DNA in the plasmid vector pBR328 was screened using Escherichia coli host strain DH1 for the expression of genes encoding putative virulence factors. A single haemolytic clone was isolated at 22 degrees C and found to contain a 3.1 kb HindIII fragment of inserted DNA. This fragment was present in seven isolates of R. salmoninarum which were examined. Western blots of extracts from clones exhibiting haemolytic activity were performed with antisera raised against either cellular or extracellular components of R. salmoninarum and failed to identify any additional proteins compared to control E. coli containing pBR328. However, minicell analysis revealed that a polypeptide with an apparent molecular mass of 65 kDa was associated with a haemolytic activity distinct from that previously described for R. salmoninarum. The nucleotide sequence of the gene encoding this product was determined and the amino acid sequence deduced. The product was 548 amino acids with a predicted molecular mass of 66757 Da and a pl of 5.57. The deduced amino acid sequence of the gene possessed strong similarities to those of a range of secreted bacterial zinc-metalloproteases and was tentatively designed hly. Neither protease nor lecithinase activities were detectable in E. coli recombinants expressing gene hly. Haemolytic activity was observed from 6 degrees C to 37 degrees C for erythrocytes from a number of mammalian species and also from fish. Gene hly was expressed in E. coli as a fusion protein consisting of maltose-binding protein at the N-terminus linked to all but the first 24 amino acids, largely constituting the putative signal peptide, of the N-terminus of Hly. The soluble fusion protein was produced and purified by affinity chromatography. Antiserum raised against the purified fusion protein was used to probe Western blots of cell lysates and extracellular products from seven isolates of R. salmoninarum

  20. Helicobacter pylori virulence genes in the five largest islands of Indonesia

    OpenAIRE

    Miftahussurur, Muhammad; Syam, Ari Fahrial; Makmun, Dadang; Nusi, Iswan Abbas; Zein, Lukman Hakim; Zulkhairi,; Akil, Fardah; Uswan, Willi Brodus; Simanjuntak, David; Uchida, Tomohisa; Adi, Pangestu; Utari, Amanda Pitarini; Rezkitha, Yudith Annisa Ayu; Subsomwong, Phawinee; Nasronudin,

    2015-01-01

    Background It remains unclear whether the low incidence of gastric cancer in Indonesia is due to low infection rates only or is also related to low Helicobacter pylori pathogenicity. We collected H. pylori strains from the five largest islands in Indonesia and evaluated genetic virulence factors. Methods The genotypes of H. pylori virulence factors were determined by polymerase chain reaction (PCR)-based sequencing. Histological severity of the gastric mucosa was classified into 4 grades, acc...

  1. Virulence of Meloidogyne incognita to expression of N gene in pepper

    OpenAIRE

    Thies, Judy A.

    2011-01-01

    Four pepper genotypes classified as resistant and four pepper genotypes classified as susceptible to several avirulent populations of M. incognita were compared for their reactions against a population of Meloidogyne incognita (Chitwood) Kofoid and White which had been shown to be virulent to resistant bell pepper (Capsicum annuum) in preliminary tests. The virulent population of M. incognita originated from a commercial bell pepper field in California. The resistant pepper genotypes used in ...

  2. Genes but not genomes reveal bacterial domestication of Lactococcus lactis.

    Directory of Open Access Journals (Sweden)

    Delphine Passerini

    Full Text Available BACKGROUND: The population structure and diversity of Lactococcus lactis subsp. lactis, a major industrial bacterium involved in milk fermentation, was determined at both gene and genome level. Seventy-six lactococcal isolates of various origins were studied by different genotyping methods and thirty-six strains displaying unique macrorestriction fingerprints were analyzed by a new multilocus sequence typing (MLST scheme. This gene-based analysis was compared to genomic characteristics determined by pulsed-field gel electrophoresis (PFGE. METHODOLOGY/PRINCIPAL FINDINGS: The MLST analysis revealed that L. lactis subsp. lactis is essentially clonal with infrequent intra- and intergenic recombination; also, despite its taxonomical classification as a subspecies, it displays a genetic diversity as substantial as that within several other bacterial species. Genome-based analysis revealed a genome size variability of 20%, a value typical of bacteria inhabiting different ecological niches, and that suggests a large pan-genome for this subspecies. However, the genomic characteristics (macrorestriction pattern, genome or chromosome size, plasmid content did not correlate to the MLST-based phylogeny, with strains from the same sequence type (ST differing by up to 230 kb in genome size. CONCLUSION/SIGNIFICANCE: The gene-based phylogeny was not fully consistent with the traditional classification into dairy and non-dairy strains but supported a new classification based on ecological separation between "environmental" strains, the main contributors to the genetic diversity within the subspecies, and "domesticated" strains, subject to recent genetic bottlenecks. Comparison between gene- and genome-based analyses revealed little relationship between core and dispensable genome phylogenies, indicating that clonal diversification and phenotypic variability of the "domesticated" strains essentially arose through substantial genomic flux within the dispensable

  3. Virulence Genes among Enterococcus faecalis and Enterococcus faecium Isolated from Coastal Beaches and Human and Nonhuman Sources in Southern California and Puerto Rico

    Directory of Open Access Journals (Sweden)

    Donna M. Ferguson

    2016-01-01

    Full Text Available Most Enterococcus faecalis and E. faecium are harmless to humans; however, strains harboring virulence genes, including esp, gelE, cylA, asa1, and hyl, have been associated with human infections. E. faecalis and E. faecium are present in beach waters worldwide, yet little is known about their virulence potential. Here, multiplex PCR was used to compare the distribution of virulence genes among E. faecalis and E. faecium isolated from beaches in Southern California and Puerto Rico to isolates from potential sources including humans, animals, birds, and plants. All five virulence genes were found in E. faecalis and E. faecium from beach water, mostly among E. faecalis. gelE was the most common among isolates from all source types. There was a lower incidence of asa1, esp, cylA, and hyl genes among isolates from beach water, sewage, septage, urban runoff, sea wrack, and eelgrass as compared to human isolates, indicating that virulent strains of E. faecalis and E. faecium may not be widely disseminated at beaches. A higher frequency of asa1 and esp among E. faecalis from dogs and of asa1 among birds (mostly seagull suggests that further studies on the distribution and virulence potential of strains carrying these genes may be warranted.

  4. Virulence Genes among Enterococcus faecalis and Enterococcus faecium Isolated from Coastal Beaches and Human and Nonhuman Sources in Southern California and Puerto Rico

    Science.gov (United States)

    Talavera, Ginamary Negrón; Hernández, Luis A. Ríos; Ambrose, Richard F.; Jay, Jennifer A.

    2016-01-01

    Most Enterococcus faecalis and E. faecium are harmless to humans; however, strains harboring virulence genes, including esp, gelE, cylA, asa1, and hyl, have been associated with human infections. E. faecalis and E. faecium are present in beach waters worldwide, yet little is known about their virulence potential. Here, multiplex PCR was used to compare the distribution of virulence genes among E. faecalis and E. faecium isolated from beaches in Southern California and Puerto Rico to isolates from potential sources including humans, animals, birds, and plants. All five virulence genes were found in E. faecalis and E. faecium from beach water, mostly among E. faecalis. gelE was the most common among isolates from all source types. There was a lower incidence of asa1, esp, cylA, and hyl genes among isolates from beach water, sewage, septage, urban runoff, sea wrack, and eelgrass as compared to human isolates, indicating that virulent strains of E. faecalis and E. faecium may not be widely disseminated at beaches. A higher frequency of asa1 and esp among E. faecalis from dogs and of asa1 among birds (mostly seagull) suggests that further studies on the distribution and virulence potential of strains carrying these genes may be warranted. PMID:27144029

  5. Virulence gene profiling and pathogenicity characterization of non-typhoidal Salmonella accounted for invasive disease in humans.

    Directory of Open Access Journals (Sweden)

    Jotham Suez

    Full Text Available Human infection with non-typhoidal Salmonella serovars (NTS infrequently causes invasive systemic disease and bacteremia. To understand better the nature of invasive NTS (iNTS, we studied the gene content and the pathogenicity of bacteremic strains from twelve serovars (Typhimurium, Enteritidis, Choleraesuis, Dublin, Virchow, Newport, Bredeney, Heidelberg, Montevideo, Schwarzengrund, 9,12:l,v:- and Hadar. Comparative genomic hybridization using a Salmonella enterica microarray revealed a core of 3233 genes present in all of the iNTS strains, which include the Salmonella pathogenicity islands 1-5, 9, 13, 14; five fimbrial operons (bcf, csg, stb, sth, sti; three colonization factors (misL, bapA, sinH; and the invasion gene, pagN. In the iNTS variable genome, we identified 16 novel genomic islets; various NTS virulence factors; and six typhoid-associated virulence genes (tcfA, cdtB, hlyE, taiA, STY1413, STY1360, displaying a wider distribution among NTS than was previously known. Characterization of the bacteremic strains in C3H/HeN mice showed clear differences in disease manifestation. Previously unreported characterization of serovars Schwarzengrund, 9,12:l,v:-, Bredeney and Virchow in the mouse model showed low ability to elicit systemic disease, but a profound and elongated shedding of serovars Schwarzengrund and 9,12:l,v:- (as well as Enteritidis and Heidelberg due to chronic infection of the mouse. Phenotypic comparison in macrophages and epithelial cell lines demonstrated a remarkable intra-serovar variation, but also showed that S. Typhimurium bacteremic strains tend to present lower intracellular growth than gastroenteritis isolates. Collectively, our data demonstrated a common core of virulence genes, which might be required for invasive salmonellosis, but also an impressive degree of genetic and phenotypic heterogeneity, highlighting that bacteremia is a complex phenotype, which cannot be attributed merely to an enhanced invasion or

  6. Virulence gene profiling and pathogenicity characterization of non-typhoidal Salmonella accounted for invasive disease in humans.

    Science.gov (United States)

    Suez, Jotham; Porwollik, Steffen; Dagan, Amir; Marzel, Alex; Schorr, Yosef Ilan; Desai, Prerak T; Agmon, Vered; McClelland, Michael; Rahav, Galia; Gal-Mor, Ohad

    2013-01-01

    Human infection with non-typhoidal Salmonella serovars (NTS) infrequently causes invasive systemic disease and bacteremia. To understand better the nature of invasive NTS (iNTS), we studied the gene content and the pathogenicity of bacteremic strains from twelve serovars (Typhimurium, Enteritidis, Choleraesuis, Dublin, Virchow, Newport, Bredeney, Heidelberg, Montevideo, Schwarzengrund, 9,12:l,v:- and Hadar). Comparative genomic hybridization using a Salmonella enterica microarray revealed a core of 3233 genes present in all of the iNTS strains, which include the Salmonella pathogenicity islands 1-5, 9, 13, 14; five fimbrial operons (bcf, csg, stb, sth, sti); three colonization factors (misL, bapA, sinH); and the invasion gene, pagN. In the iNTS variable genome, we identified 16 novel genomic islets; various NTS virulence factors; and six typhoid-associated virulence genes (tcfA, cdtB, hlyE, taiA, STY1413, STY1360), displaying a wider distribution among NTS than was previously known. Characterization of the bacteremic strains in C3H/HeN mice showed clear differences in disease manifestation. Previously unreported characterization of serovars Schwarzengrund, 9,12:l,v:-, Bredeney and Virchow in the mouse model showed low ability to elicit systemic disease, but a profound and elongated shedding of serovars Schwarzengrund and 9,12:l,v:- (as well as Enteritidis and Heidelberg) due to chronic infection of the mouse. Phenotypic comparison in macrophages and epithelial cell lines demonstrated a remarkable intra-serovar variation, but also showed that S. Typhimurium bacteremic strains tend to present lower intracellular growth than gastroenteritis isolates. Collectively, our data demonstrated a common core of virulence genes, which might be required for invasive salmonellosis, but also an impressive degree of genetic and phenotypic heterogeneity, highlighting that bacteremia is a complex phenotype, which cannot be attributed merely to an enhanced invasion or intracellular

  7. Structure of Vibrio cholerae ToxT reveals a mechanism for fatty acid regulation of virulence genes

    Energy Technology Data Exchange (ETDEWEB)

    Lowden, Michael J.; Skorupski, Karen; Pellegrini, Maria; Chiorazzo, Michael G.; Taylor, Ronald K.; Kull, F. Jon (Dartmouth)

    2010-03-04

    Cholera is an acute intestinal infection caused by the bacterium Vibrio cholerae. In order for V. cholerae to cause disease, it must produce two virulence factors, the toxin-coregulated pilus (TCP) and cholera toxin (CT), whose expression is controlled by a transcriptional cascade culminating with the expression of the AraC-family regulator, ToxT. We have solved the 1.9 {angstrom} resolution crystal structure of ToxT, which reveals folds in the N- and C-terminal domains that share a number of features in common with AraC, MarA, and Rob as well as the unexpected presence of a buried 16-carbon fatty acid, cis-palmitoleate. The finding that cis-palmitoleic acid reduces TCP and CT expression in V. cholerae and prevents ToxT from binding to DNA in vitro provides a direct link between the host environment of V. cholerae and regulation of virulence gene expression.

  8. Distribution of classical and nonclassical virulence genes in enterotoxigenic Escherichia coli isolates from Chilean children and tRNA gene screening for putative insertion sites for genomic islands.

    Science.gov (United States)

    Del Canto, Felipe; Valenzuela, Patricio; Cantero, Lidia; Bronstein, Jonathan; Blanco, Jesús E; Blanco, Jorge; Prado, Valeria; Levine, Myron; Nataro, James; Sommerfelt, Halvor; Vidal, Roberto

    2011-09-01

    Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrhea. Three adhesins (Tia, TibA, EtpA), an iron acquisition system (Irp1, Irp2, and FyuA), a GTPase (LeoA), and an autotransporter (EatA) are ETEC virulence-related proteins that, in contrast to the classical virulence factors (enterotoxins and fimbrial colonization factors) have not heretofore been targets in characterizing isolates from epidemiological studies. Here, we determined the occurrence of these nonclassical virulence genes in 103 ETEC isolates from Chilean children with diarrhea and described their association with O serogroups and classical virulence determinants. Because tia, leoA, irp2, and fyuA are harbored by pathogenicity islands inserted into the selC and asnT tRNA genes (tDNAs), we analyzed the regions flanking these loci. Ten additional tDNAs were also screened to identify hot spots for genetic insertions. Associations between the most frequent serogroups and classical colonization factor (CF)-toxin profiles included O6/LT-STh/CS1-CS3-CS21 (i.e., O6 serogroup, heat-labile [LT] and human heat-stable [STh] enterotoxins, and CFs CS1, -3 and -21), O6/LT-STh/CS2-CS3-CS21, and O104-O127/STh/CFAI-CS21. The eatA and etpA genes were detected in more than 70% of the collection, including diverse serogroups and virulence profiles. Sixteen percent of the ETEC strains were negative for classical and nonclassical adhesins, suggesting the presence of unknown determinants of adhesion. The leuX, thrW, and asnT tDNAs were disrupted in more than 65% of strains, suggesting they are hot spots for the insertion of mobile elements. Sequences similar to integrase genes were identified next to the thrW, asnT, pheV, and selC tDNAs. We propose that the eatA and etpA genes should be included in characterizations of ETEC isolates in future epidemiological studies to determine their prevalence in other geographical regions. Sequencing of tDNA-associated genetic insertions might identify new ETEC virulence

  9. Defining the Metabolic Functions and Roles in Virulence of the rpoN1 and rpoN2 Genes in Ralstonia solanacearum GMI1000.

    Directory of Open Access Journals (Sweden)

    Benjamin R Lundgren

    Full Text Available The alternative sigma factor RpoN is a unique regulator found among bacteria. It controls numerous processes that range from basic metabolism to more complex functions such as motility and nitrogen fixation. Our current understanding of RpoN function is largely derived from studies on prototypical bacteria such as Escherichia coli. Bacillus subtilis and Pseudomonas putida. Although the extent and necessity of RpoN-dependent functions differ radically between these model organisms, each bacterium depends on a single chromosomal rpoN gene to meet the cellular demands of RpoN regulation. The bacterium Ralstonia solanacearum is often recognized for being the causative agent of wilt disease in crops, including banana, peanut and potato. However, this plant pathogen is also one of the few bacterial species whose genome possesses dual rpoN genes. To determine if the rpoN genes in this bacterium are genetically redundant and interchangeable, we constructed and characterized ΔrpoN1, ΔrpoN2 and ΔrpoN1 ΔrpoN2 mutants of R. solanacearum GMI1000. It was found that growth on a small range of metabolites, including dicarboxylates, ethanol, nitrate, ornithine, proline and xanthine, were dependent on only the rpoN1 gene. Furthermore, the rpoN1 gene was required for wilt disease on tomato whereas rpoN2 had no observable role in virulence or metabolism in R. solanacearum GMI1000. Interestingly, plasmid-based expression of rpoN2 did not fully rescue the metabolic deficiencies of the ΔrpoN1 mutants; full recovery was specific to rpoN1. In comparison, only rpoN2 was able to genetically complement a ΔrpoN E. coli mutant. These results demonstrate that the RpoN1 and RpoN2 proteins are not functionally equivalent or interchangeable in R. solanacearum GMI1000.

  10. Defining the Metabolic Functions and Roles in Virulence of the rpoN1 and rpoN2 Genes in Ralstonia solanacearum GMI1000.

    Science.gov (United States)

    Lundgren, Benjamin R; Connolly, Morgan P; Choudhary, Pratibha; Brookins-Little, Tiffany S; Chatterjee, Snigdha; Raina, Ramesh; Nomura, Christopher T

    2015-01-01

    The alternative sigma factor RpoN is a unique regulator found among bacteria. It controls numerous processes that range from basic metabolism to more complex functions such as motility and nitrogen fixation. Our current understanding of RpoN function is largely derived from studies on prototypical bacteria such as Escherichia coli. Bacillus subtilis and Pseudomonas putida. Although the extent and necessity of RpoN-dependent functions differ radically between these model organisms, each bacterium depends on a single chromosomal rpoN gene to meet the cellular demands of RpoN regulation. The bacterium Ralstonia solanacearum is often recognized for being the causative agent of wilt disease in crops, including banana, peanut and potato. However, this plant pathogen is also one of the few bacterial species whose genome possesses dual rpoN genes. To determine if the rpoN genes in this bacterium are genetically redundant and interchangeable, we constructed and characterized ΔrpoN1, ΔrpoN2 and ΔrpoN1 ΔrpoN2 mutants of R. solanacearum GMI1000. It was found that growth on a small range of metabolites, including dicarboxylates, ethanol, nitrate, ornithine, proline and xanthine, were dependent on only the rpoN1 gene. Furthermore, the rpoN1 gene was required for wilt disease on tomato whereas rpoN2 had no observable role in virulence or metabolism in R. solanacearum GMI1000. Interestingly, plasmid-based expression of rpoN2 did not fully rescue the metabolic deficiencies of the ΔrpoN1 mutants; full recovery was specific to rpoN1. In comparison, only rpoN2 was able to genetically complement a ΔrpoN E. coli mutant. These results demonstrate that the RpoN1 and RpoN2 proteins are not functionally equivalent or interchangeable in R. solanacearum GMI1000. PMID:26659655

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

    Directory of Open Access Journals (Sweden)

    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.

  12. A new experimental approach for studying bacterial genomic island evolution identifies island genes with bacterial host-specific expression patterns

    Directory of Open Access Journals (Sweden)

    Nickerson Cheryl A

    2006-01-01

    Full Text Available Abstract Background Genomic islands are regions of bacterial genomes that have been acquired by horizontal transfer and often contain blocks of genes that function together for specific processes. Recently, it has become clear that the impact of genomic islands on the evolution of different bacterial species is significant and represents a major force in establishing bacterial genomic variation. However, the study of genomic island evolution has been mostly performed at the sequence level using computer software or hybridization analysis to compare different bacterial genomic sequences. We describe here a novel experimental approach to study the evolution of species-specific bacterial genomic islands that identifies island genes that have evolved in such a way that they are differentially-expressed depending on the bacterial host background into which they are transferred. Results We demonstrate this approach by using a "test" genomic island that we have cloned from the Salmonella typhimurium genome (island 4305 and transferred to a range of Gram negative bacterial hosts of differing evolutionary relationships to S. typhimurium. Systematic analysis of the expression of the island genes in the different hosts compared to proper controls allowed identification of genes with genera-specific expression patterns. The data from the analysis can be arranged in a matrix to give an expression "array" of the island genes in the different bacterial backgrounds. A conserved 19-bp DNA site was found upstream of at least two of the differentially-expressed island genes. To our knowledge, this is the first systematic analysis of horizontally-transferred genomic island gene expression in a broad range of Gram negative hosts. We also present evidence in this study that the IS200 element found in island 4305 in S. typhimurium strain LT2 was inserted after the island had already been acquired by the S. typhimurium lineage and that this element is likely not

  13. KdgR, an IClR Family Transcriptional Regulator, Inhibits Virulence Mainly by Repression of hrp Genes in Xanthomonas oryzae pv. oryzae▿

    OpenAIRE

    Lu, Yao; Rashidul, Islam M.; Hirata, Hisae; Tsuyumu, Shinji

    2011-01-01

    KdgR has been reported to negatively regulate the genes involved in degradation and metabolization of pectic acid and other extracellular enzymes in soft-rotting Erwinia spp. through direct binding to their promoters. The possible involvement of a KdgR orthologue in virulence by affecting the expression of extracellular enzymes in Xanthomonas oryzae pv. oryzae, the causal agent of rice blight disease, was examined by comparing virulence and regulation of extracellular enzymes between the wild...

  14. Colistin Resistance in a Clinical Acinetobacter baumannii Strain Appearing after Colistin Treatment: Effect on Virulence and Bacterial Fitness

    OpenAIRE

    López-Rojas, Rafael; McConnell, Michael J.; Jiménez-Mejías, Manuel Enrique; Domínguez-Herrera, Juan; Fernández-Cuenca, Felipe; Pachón, Jerónimo

    2013-01-01

    The fitness and virulence costs associated with the clinical acquisition of colistin resistance by Acinetobacter baumannii were evaluated. The growth of strain CR17 (colistin resistant) was less than that of strain CS01 (colistin susceptible) when the strains were grown in competition (72-h competition index, 0.008). In a murine sepsis model, CS01 and CR17 reached spleen concentrations when coinfecting of 9.31 and 6.97 log10 CFU/g, respectively, with an in vivo competition index of 0.016. Mor...

  15. Host-specificity of Staphylococcus aureus causing intramammary infections in dairy animals assessed by genotyping and virulence genes.

    Science.gov (United States)

    Bar-Gal, G Kahila; Blum, S E; Hadas, L; Ehricht, R; Monecke, S; Leitner, G

    2015-03-23

    Staphylococcus aureus is one of the most relevant pathogens causing clinical and subclinical, chronic mastitis in dairy animals. Routinely, mastitis pathogens are isolated and classified to genus or species level, and regarded as single entities. However, S. aureus includes a broad range of genotypes with distinct pathogenic and epidemiologic characteristics. The objective of the present study was to assess the host-specificity of S. aureus causing mastitis in dairy animals, based on phylogenetic and genotypic characterization as well as the presence of virulence and antimicrobial resistance genes in the pathogen genome. S. aureus isolates from mastitis in cows, sheep and goats in Israel, and from cows in Germany, the USA and Italy, were compared by the following methods: a. Bayesian phylogenetic comparison of sequences of genes nuc, coa, lukF and clfA, b. genotyping by spa and agr typing, and assignment to MLST Clonal Complexes (MLST CC), and c. the presence of a broad array of virulence and antimicrobial resistance genes. Overall, phylogenetic, virulence and genotyping approaches agreed with each other. Cow isolates could be differentiated from sheep and goat isolates with all three methods, with different resolution. In two phylogenetic clusters, segregation was found also between cow isolates from Israel and abroad. Sheep and goats' isolates showed less variability than isolates from cows in all methods used. In conclusion, different S. aureus lineages are associated to cows in contrast to goats and sheep, suggesting co-evolution between pathogen and host species. Modern diagnostics approaches should aim to explore molecular data for a better understanding and cost-effective management of mastitis. PMID:25631254

  16. Repression of virulence genes by phosphorylation-dependent oligomerization of CsrR at target promoters in S. pyogenes.

    Science.gov (United States)

    Miller, A A; Engleberg, N C; DiRita, V J

    2001-05-01

    csrRS encodes a two-component regulatory system that represses the transcription of a number of virulence factors in Streptococcus pyogenes, including the hyaluronic acid capsule and pyrogenic exotoxin B. CsrRS-regulated virulence factors have diverse functions during pathogenesis and are differentially expressed throughout growth. This suggests that multiple signals induce CsrRS-mediated gene regulation, or that regulated genes respond differently to CsrR, or both. As a first step in dissecting the csrRS signal transduction pathway, we determined the mechanism by which CsrR mediates the repression of its target promoters. We found that phosphorylated CsrR binds directly to all but one of the promoters of its regulated genes, with different affinities. Phosphorylation of CsrR enhances both oligomerization and DNA binding. We defined the binding site of CsrR at each of the regulated promoters using DNase I and hydroxyl radical footprinting. Based on these results, we propose a model for differential regulation by CsrRS. PMID:11401704

  17. cis-Acting Elements That Control Expression of the Master Virulence Regulatory Gene atxA in Bacillus anthracis

    OpenAIRE

    Dale, Jennifer L.; Raynor, Malik J.; Dwivedi, Prabhat; Koehler, Theresa M.

    2012-01-01

    Transcription of the Bacillus anthracis structural genes for the anthrax toxin proteins and biosynthetic operon for capsule is positively regulated by AtxA, a transcription regulator with unique properties. Consistent with the role of atxA in virulence factor expression, a B. anthracis atxA-null mutant is avirulent in a murine model for anthrax. In culture, multiple signals impact atxA transcript levels, and the timing and steady-state level of atxA expression are critical for optimal toxin a...

  18. Systems analysis of multiple regulator perturbations allows discovery of virulence factors in Salmonella

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Hyunjin; Ansong, Charles; McDermott, Jason E.; Gritsenko, Marina A.; Smith, Richard D.; Heffron, Fred; Adkins, Joshua N.

    2011-06-28

    Background: Systemic bacterial infections are highly regulated and complex processes that are orchestrated by numerous virulence factors. Genes that are coordinately controlled by the set of regulators required for systemic infection are potentially required for pathogenicity. Results: In this study we present a systems biology approach in which sample-matched multi-omic measurements of fourteen virulence-essential regulator mutants were coupled with computational network analysis to efficiently identify Salmonella virulence factors. Immunoblot experiments verified network-predicted virulence factors and a subset was determined to be secreted into the host cytoplasm, suggesting that they are virulence factors directly interacting with host cellular components. Two of these, SrfN and PagK2, were required for full mouse virulence and were shown to be translocated independent of either of the type III secretion systems in Salmonella or the type III injectisome-related flagellar mechanism. Conclusions: Integrating multi-omic datasets from Salmonella mutants lacking virulence regulators not only identified novel virulence factors but also defined a new class of translocated effectors involved in pathogenesis. The success of this strategy at discovery of known and novel virulence factors suggests that the approach may have applicability for other bacterial pathogens.

  19. The Salmonella typhimurium katF (rpoS) gene: cloning, nucleotide sequence, and regulation of spvR and spvABCD virulence plasmid genes.

    OpenAIRE

    Kowarz, L; Coynault, C; Robbe-Saule, V; Norel, F.

    1994-01-01

    The spv region of Salmonella virulence plasmids is essential for the development of a systemic infection in mice. Transcriptional activation of the spvABCD operon occurs during stationary growth phase and is mediated by the regulatory gene product SpvR. We have previously shown that expression of a spvRAB'-cat fusion in Escherichia coli was dependent on the katF (rpoS) locus which encodes an alternative sigma factor (sigma S). The katF gene from Salmonella typhimurium has been cloned, sequenc...

  20. Genetic Characterization of ExPEC-Like Virulence Plasmids among a Subset of NMEC.

    Science.gov (United States)

    Nicholson, Bryon A; West, Aaron C; Mangiamele, Paul; Barbieri, Nicolle; Wannemuehler, Yvonne; Nolan, Lisa K; Logue, Catherine M; Li, Ganwu

    2016-01-01

    Neonatal Meningitis Escherichia coli (NMEC) is one of the most common causes of neonatal bacterial meningitis in the US and elsewhere resulting in mortality or neurologic deficits in survivors. Large plasmids have been shown experimentally to increase the virulence of NMEC in the rat model of neonatal meningitis. Here, 9 ExPEC-like plasmids were isolated from NMEC and sequenced to identify the core and accessory plasmid genes of ExPEC-like virulence plasmids in NMEC and create an expanded plasmid phylogeny. Results showed sequenced virulence plasmids carry a strongly conserved core of genes with predicted functions in five distinct categories including: virulence, metabolism, plasmid stability, mobile elements, and unknown genes. The major functions of virulence-associated and plasmid core genes serve to increase in vivo fitness by adding multiple iron uptake systems to the genetic repertoire to facilitate NMEC's survival in the host's low iron environment, and systems to enhance bacterial resistance to host innate immunity. Phylogenetic analysis based on these core plasmid genes showed that at least two lineages of ExPEC-like plasmids could be discerned. Further, virulence plasmids from Avian Pathogenic E. coli and NMEC plasmids could not be differentiated based solely on the genes of the core plasmid genome. PMID:26800268

  1. Genetic Characterization of ExPEC-Like Virulence Plasmids among a Subset of NMEC.

    Directory of Open Access Journals (Sweden)

    Bryon A Nicholson

    Full Text Available Neonatal Meningitis Escherichia coli (NMEC is one of the most common causes of neonatal bacterial meningitis in the US and elsewhere resulting in mortality or neurologic deficits in survivors. Large plasmids have been shown experimentally to increase the virulence of NMEC in the rat model of neonatal meningitis. Here, 9 ExPEC-like plasmids were isolated from NMEC and sequenced to identify the core and accessory plasmid genes of ExPEC-like virulence plasmids in NMEC and create an expanded plasmid phylogeny. Results showed sequenced virulence plasmids carry a strongly conserved core of genes with predicted functions in five distinct categories including: virulence, metabolism, plasmid stability, mobile elements, and unknown genes. The major functions of virulence-associated and plasmid core genes serve to increase in vivo fitness by adding multiple iron uptake systems to the genetic repertoire to facilitate NMEC's survival in the host's low iron environment, and systems to enhance bacterial resistance to host innate immunity. Phylogenetic analysis based on these core plasmid genes showed that at least two lineages of ExPEC-like plasmids could be discerned. Further, virulence plasmids from Avian Pathogenic E. coli and NMEC plasmids could not be differentiated based solely on the genes of the core plasmid genome.

  2. PCR detection of seven virulence and toxin genes of Campylobacter jejuni and Campylobacter coli isolates from Danish pigs and cattle and cytolethal distending toxin production of the isolates

    DEFF Research Database (Denmark)

    Bang, Dang Duong; Nielsen, E.M.; Scheutz, F.;

    2003-01-01

    Aims: To study the prevalence of seven virulence and toxin genes, and cytolethal distending toxin (CDT) production of Campylobacter jejuni and C. coli isolates from Danish pigs and cattle. Methods and Results: The presence of the cadF, ceuE, virB11, flaA, cdtA, cdtB, cdtC and the cdt gene cluster...

  3. Pathogenesis of Streptococcus urinary tract infection depends on bacterial strain and β-hemolysin/cytolysin that mediates cytotoxicity, cytokine synthesis, inflammation and virulence.

    Science.gov (United States)

    Leclercq, Sophie Y; Sullivan, Matthew J; Ipe, Deepak S; Smith, Joshua P; Cripps, Allan W; Ulett, Glen C

    2016-01-01

    Streptococcus agalactiae can cause urinary tract infection (UTI) including cystitis and asymptomatic bacteriuria (ABU). The early host-pathogen interactions that occur during S. agalactiae UTI and subsequent mechanisms of disease pathogenesis are poorly defined. Here, we define the early interactions between human bladder urothelial cells, monocyte-derived macrophages, and mouse bladder using uropathogenic S. agalactiae (UPSA) 807 and ABU-causing S. agalactiae (ABSA) 834 strains. UPSA 807 adhered, invaded and killed bladder urothelial cells more efficiently compared to ABSA 834 via mechanisms including low-level caspase-3 activation, and cytolysis, according to lactate dehydrogenase release measures and cell viability. Severe UPSA 807-induced cytotoxicity was mediated entirely by the bacterial β-hemolysin/cytolysin (β-H/C) because an β-H/C-deficient UPSA 807 isogenic mutant, UPSA 807ΔcylE, was not cytotoxic in vitro; the mutant was also significantly attenuated for colonization in the bladder in vivo. Analysis of infection-induced cytokines, including IL-8, IL-1β, IL-6 and TNF-α in vitro and in vivo revealed that cytokine and chemokine responses were dependent on expression of β-H/C that also elicited severe bladder neutrophilia. Thus, virulence of UPSA 807 encompasses adhesion to, invasion of and killing of bladder cells, pro-inflammatory cytokine/chemokine responses that elicit neutrophil infiltration, and β-H/C-mediated subversion of innate immune-mediated bacterial clearance from the bladder. PMID:27383371

  4. Whole-genome sequence analysis of Pseudomonas syringae pv. phaseolicola 1448A reveals divergence among pathovars in genes involved in virulence and transposition.

    Science.gov (United States)

    Joardar, Vinita; Lindeberg, Magdalen; Jackson, Robert W; Selengut, Jeremy; Dodson, Robert; Brinkac, Lauren M; Daugherty, Sean C; Deboy, Robert; Durkin, A Scott; Giglio, Michelle Gwinn; Madupu, Ramana; Nelson, William C; Rosovitz, M J; Sullivan, Steven; Crabtree, Jonathan; Creasy, Todd; Davidsen, Tanja; Haft, Dan H; Zafar, Nikhat; Zhou, Liwei; Halpin, Rebecca; Holley, Tara; Khouri, Hoda; Feldblyum, Tamara; White, Owen; Fraser, Claire M; Chatterjee, Arun K; Cartinhour, Sam; Schneider, David J; Mansfield, John; Collmer, Alan; Buell, C Robin

    2005-09-01

    Pseudomonas syringae pv. phaseolicola, a gram-negative bacterial plant pathogen, is the causal agent of halo blight of bean. In this study, we report on the genome sequence of P. syringae pv. phaseolicola isolate 1448A, which encodes 5,353 open reading frames (ORFs) on one circular chromosome (5,928,787 bp) and two plasmids (131,950 bp and 51,711 bp). Comparative analyses with a phylogenetically divergent pathovar, P. syringae pv. tomato DC3000, revealed a strong degree of conservation at the gene and genome levels. In total, 4,133 ORFs were identified as putative orthologs in these two pathovars using a reciprocal best-hit method, with 3,941 ORFs present in conserved, syntenic blocks. Although these two pathovars are highly similar at the physiological level, they have distinct host ranges; 1448A causes disease in beans, and DC3000 is pathogenic on tomato and Arabidopsis. Examination of the complement of ORFs encoding virulence, fitness, and survival factors revealed a substantial, but not complete, overlap between these two pathovars. Another distinguishing feature between the two pathovars is their distinctive sets of transposable elements. With access to a fifth complete pseudomonad genome sequence, we were able to identify 3,567 ORFs that likely comprise the core Pseudomonas genome and 365 ORFs that are P. syringae specific. PMID:16159782

  5. Comparison of Methods to Identify Pathogens and Associated Virulence Functional Genes in Biosolids from Two Different Wastewater Treatment Facilities in Canada

    Science.gov (United States)

    Masson, Luke; Elias, Miria; Xiang, Shurong; Madey, Ewa; Huang, Hongsheng; Brooks, Brian; Beaudette, Lee A.

    2016-01-01

    The use of treated municipal wastewater residues (biosolids) as fertilizers is an attractive, inexpensive option for growers and farmers. Various regulatory bodies typically employ indicator organisms (fecal coliforms, E. coli and Salmonella) to assess the adequacy and efficiency of the wastewater treatment process in reducing pathogen loads in the final product. Molecular detection approaches can offer some advantages over culture-based methods as they can simultaneously detect a wider microbial species range, including non-cultivable microorganisms. However, they cannot directly assess the viability of the pathogens. Here, we used bacterial enumeration methods together with molecular methods including qPCR, 16S rRNA and cpn60 gene amplicon sequencing and shotgun metagenomic sequencing to compare pre- and post-treatment biosolids from two Canadian wastewater treatment plants (WWTPs). Our results show that an anaerobic digestion WWTP was unsuccessful at reducing the live indicator organism load (coliforms, generic E. coli and Salmonella) below acceptable regulatory criteria, while biosolids from a dewatering/pelletization WWTP met these criteria. DNA from other pathogens was detected by the molecular methods, but these species were considered less abundant. Clostridium DNA increased significantly following anaerobic digestion treatments. In addition to pathogen DNA, genes related to virulence and antibiotic resistance were identified in treated biosolids. Shotgun metagenomics revealed the widest range of pathogen DNA and, among the approaches used here, was the only approach that could access functional gene information in treated biosolids. Overall, our results highlight the potential usefulness of amplicon sequencing and shotgun metagenomics as complementary screening methods that could be used in parallel with culture-based methods, although more detailed comparisons across a wider range of sites would be needed. PMID:27089040

  6. Comparison of Methods to Identify Pathogens and Associated Virulence Functional Genes in Biosolids from Two Different Wastewater Treatment Facilities in Canada.

    Science.gov (United States)

    Yergeau, Etienne; Masson, Luke; Elias, Miria; Xiang, Shurong; Madey, Ewa; Huang, Hongsheng; Brooks, Brian; Beaudette, Lee A

    2016-01-01

    The use of treated municipal wastewater residues (biosolids) as fertilizers is an attractive, inexpensive option for growers and farmers. Various regulatory bodies typically employ indicator organisms (fecal coliforms, E. coli and Salmonella) to assess the adequacy and efficiency of the wastewater treatment process in reducing pathogen loads in the final product. Molecular detection approaches can offer some advantages over culture-based methods as they can simultaneously detect a wider microbial species range, including non-cultivable microorganisms. However, they cannot directly assess the viability of the pathogens. Here, we used bacterial enumeration methods together with molecular methods including qPCR, 16S rRNA and cpn60 gene amplicon sequencing and shotgun metagenomic sequencing to compare pre- and post-treatment biosolids from two Canadian wastewater treatment plants (WWTPs). Our results show that an anaerobic digestion WWTP was unsuccessful at reducing the live indicator organism load (coliforms, generic E. coli and Salmonella) below acceptable regulatory criteria, while biosolids from a dewatering/pelletization WWTP met these criteria. DNA from other pathogens was detected by the molecular methods, but these species were considered less abundant. Clostridium DNA increased significantly following anaerobic digestion treatments. In addition to pathogen DNA, genes related to virulence and antibiotic resistance were identified in treated biosolids. Shotgun metagenomics revealed the widest range of pathogen DNA and, among the approaches used here, was the only approach that could access functional gene information in treated biosolids. Overall, our results highlight the potential usefulness of amplicon sequencing and shotgun metagenomics as complementary screening methods that could be used in parallel with culture-based methods, although more detailed comparisons across a wider range of sites would be needed. PMID:27089040

  7. Anti-hemolytic, hemagglutination inhibition and bacterial membrane disruptive properties of selected herbal extracts attenuate virulence of Carbapenem Resistant Escherichia coli.

    Science.gov (United States)

    Thakur, Pallavi; Chawla, Raman; Narula, Alka; Goel, Rajeev; Arora, Rajesh; Sharma, Rakesh Kumar

    2016-06-01

    Expression of a multitude of virulence factors by multi-drug resistant microbial strains, e.g., Carbapenem Resistant Escherichia coli (Family: Enterobacteriaceae; Class: Gammaproteobacteria), is responsible for resistance against beta-lactam antibiotics. Hemolysin production and induction of hemagglutination by bacterial surface receptors inflicts direct cytotoxicity by destroying host phagocytic and epithelial cells. We have previously reported that Berberis aristata, Camellia sinensis, Cyperus rotundus Holarrhena antidysenterica and Andrographis paniculata are promising herbal leads for targeting Carbapenem resistant Escherichia coli. These herbal leads were analyzed for their anti-hemolytic potential by employing spectrophotometric assay of hemoglobin liberation. Anti-hemagglutination potential of the extracts was assessed by employing qualitative assay of visible RBC aggregate formation. Camellia sinensis (PTRC-31911-A) exhibited anti-hemolytic potential of 73.97 ± 0.03%, followed by Holarrhena antidysenterica (PTRC-8111-A) i.e., 68.32 ± 0.05%, Berberis aristata (PTRC-2111-A) i.e., 60.26 ± 0.05% and Cyperus rotundus (PTRC-31811-A) i.e., 53.76 ± 0.03%. Comprehensive, visual analysis of hemagglutination inhibition revealed that only Berberis aristata (PTRC-2111-A) and Camellia sinensis (PTRC-31911-A) exhibited anti-hemagglutination activity. However, Andrographis paniculata (PTRC-11611-A) exhibited none of the inhibitory activities. Furthermore, the pair wise correlation analysis of the tested activities with quantitative phytochemical descriptors revealed that an increased content of alkaloid; flavonoids; polyphenols, and decreased content of saponins supported both the activities. Additionally, flow cytometry revealed that cell membrane structures of CRE were damaged by extracts of Berberis aristata (PTRC-2111-A) and Camellia sinensis (PTRC-31911-A) at their respective Minimum Inhibitory Concentrations, thereby confirming noteworthy antibacterial

  8. Expression of virulence-related genes in Listeria monocytogenes grown on Danish hard cheese as affected by NaCl content

    DEFF Research Database (Denmark)

    Larsen, Nadja; Jespersen, Lene

    2015-01-01

    Expression of virulence-related genes in Listeria monocytogenes incubated on cheese was assessed by real-time quantitative polymerase chain reaction. The objective of the study was to investigate the impact of sodium chloride concentration in cheese on transcription of virulence genes and, thereby......, virulence potential of L. monocytogenes. The expression studies were performed with L. monocytogenes strains characterized by different tolerance to salt stress. Strains ATCC(®) 51779 and DSMZ 15675 were incubated on the Danish hard-cheese type Samsoe, with low (<0.15% [wt/wt]) and high (3.6% [wt...... responses in L. monocytogenes. The more sensitive strain ATCC(®) 51779 was most responsive, showing significant upregulation of prfA, actA, hly, and bsh both at low and high NaCl. Strain DSMZ 15675 was less responsive to NaCl stress, showing reduced or consistent gene transcription at all conditions...

  9. Evaluation of adherence, hemagglutination, and presence of genes codifying for virulence factors of Acinetobacter baumannii causing urinary tract infection

    Directory of Open Access Journals (Sweden)

    Graziela Braun

    2004-12-01

    Full Text Available Acinetobacter baumannii is a strictly aerobic bacterium which causes severe infections, however its pathogenic characteristics are not well defined. Thirteen A. baumannii strains isolated from urine of hospitalized and nonhospitalized patients with different ages were investigated for the presence of virulence factors. The isolates belonged to biotypes 2, 6, and 9 and were sensitive to imipenem. The majority of them showed resistance to amikacin, ceftazidime, ceftriaxone, ciprofloxacin, gentamicin, norfloxacin, and trimethoprim-sulfamethoxazole. None of A. baumannii strains presented genes codifying for 17 different virulence factors previously described in uropathogenic Escherichia coli, when tested by polymerase chain reaction (PCR. Nine isolates agglutinated human group AB erythrocytes, in presence of mannose, but none of them agglutinated group O erythrocytes. Adherence to polystyrene was observed in 7 isolates, and this result did not correlate with that obtained in hemagglutination assay. All the isolates were able to grow in iron-limiting conditions, showing that A. baumannii produces some type of siderophore. However, the genes iutA and fyuA, from iron uptake system of E. coli and Yersinia sp., respectively, were not present in the isolates, suggesting the presence of a different type of siderophore. The fimbriae of A. baumannii strains that mediates the adherence are possibly mannose-resistant, eventhough the mechanism of adherence to human epithelial cells still remains to be elucidated.

  10. Evaluating bacterial gene-finding HMM structures as probabilistic logic programs

    DEFF Research Database (Denmark)

    Mørk, Søren; Holmes, Ian

    2012-01-01

    Motivation: Probabilistic logic programming offers a powerful way to describe and evaluate structured statistical models. To investigate the practicality of probabilistic logic programming for structure learning in bioinformatics, we undertook a simplified bacterial gene-finding benchmark in PRISM...... modeling and three-state versions of the five model structures. The models are all represented as probabilistic logic programs and evaluated using the PRISM machine learning system in terms of statistical information criteria and gene-finding prediction accuracy, in two bacterial genomes. Neither of our......, a probabilistic dialect of Prolog. Results: We evaluate Hidden Markov Model structures for bacterial protein-coding gene potential, including a simple null model structure, three structures based on existing bacterial gene finders and two novel model structures. We test standard versions as well as ADPH length...

  11. Shigella in Brazilian children with acute diarrhoea: prevalence, antimicrobial resistance and virulence genes

    OpenAIRE

    Mireille Ângela Bernardes Sousa; Edilberto Nogueira Mendes; Guilherme Birchal Collares; Luciano Amedée Péret-Filho; Francisco José Penna; Paula Prazeres Magalhães

    2013-01-01

    Diarrhoeal disease is still considered a major cause of morbidity and mortality among children. Among diarrhoeagenic agents, Shigella should be highlighted due to its prevalence and the severity of the associated disease. Here, we assessed Shigella prevalence, drug susceptibility and virulence factors. Faeces from 157 children with diarrhoea who sought treatment at the Children's Hospital João Paulo II, a reference children´s hospital in Belo Horizonte, state of Minas Gerais, Brazil, were cul...

  12. Ionome changes in Xylella fastidiosa-infected Nicotiana tabacum correlate with virulence and discriminate between subspecies of bacterial isolates.

    Science.gov (United States)

    Oliver, J E; Sefick, S A; Parker, J K; Arnold, T; Cobine, P A; De La Fuente, L

    2014-10-01

    Characterization of ionomes has been used to uncover the basis of nutrient utilization and environmental adaptation of plants. Here, ionomic profiles were used to understand the phenotypic response of a plant to infection by genetically diverse isolates of Xylella fastidiosa, a gram-negative, xylem-limited bacterial plant pathogen. In this study, X. fastidiosa isolates were used to infect a common model host (Nicotiana tabacum 'SR1'), and leaf and sap concentrations of eleven elements together with plant colonization and symptoms were assessed. Multivariate statistical analysis revealed that changes in the ionome were significantly correlated with symptom severity and bacterial populations in host petioles. Moreover, plant ionome modification by infection could be used to differentiate the X. fastidiosa subspecies with which the plant was infected. This report establishes host ionome modification as a phenotypic response to infection. PMID:24983508

  13. Comparison on Virulence and Immunogenicity of Two Recombinant Vaccinia Vaccines, Tian Tan and Guang9 Strains, Expressing the HIV-1 Envelope Gene

    OpenAIRE

    Zhu, Rong; Huang, Weijin; Wang, Wenbo; Liu, Qiang; Nie, Jianhui; Meng, Shufang; Yu, Yongxin; Wang, Youchun

    2012-01-01

    Background The vaccinia virus Guang9 strain (VG9), derived from the vaccinia virus Tian Tan strain (VTT) has been found to be less virulent than VTT. Methodology/Principal Findings To investigate whether VG9 could be a potential replicating virus vector, the TK genes in VG9 and VTT were replaced with the HIV-1 envelope gene via homologous recombination, resulting in the recombinant viruses, VG9-E and VTT-E. The biology, virulence, humoral and cellular immunological responses of VG9-E and VTT-...

  14. Comparison on Virulence and Immunogenicity of Two Recombinant Vaccinia Vaccines, Tian Tan and Guang9 Strains, Expressing the HIV-1 Envelope Gene

    OpenAIRE

    Rong Zhu; Weijin Huang; Wenbo Wang; Qiang Liu; Jianhui Nie; Shufang Meng; Yongxin Yu; Youchun Wang

    2012-01-01

    BACKGROUND: The vaccinia virus Guang9 strain (VG9), derived from the vaccinia virus Tian Tan strain (VTT) has been found to be less virulent than VTT. METHODOLOGY/PRINCIPAL FINDINGS: To investigate whether VG9 could be a potential replicating virus vector, the TK genes in VG9 and VTT were replaced with the HIV-1 envelope gene via homologous recombination, resulting in the recombinant viruses, VG9-E and VTT-E. The biology, virulence, humoral and cellular immunological responses of VG9-E and VT...

  15. Horizontal gene transfer of zinc and non-zinc forms of bacterial ribosomal protein S4

    Directory of Open Access Journals (Sweden)

    Luthey-Schulten Zaida

    2009-07-01

    Full Text Available Abstract Background The universal ribosomal protein S4 is essential for the initiation of small subunit ribosomal assembly and translational accuracy. Being part of the information processing machinery of the cell, the gene for S4 is generally thought of as being inherited vertically and has been used in concatenated gene phylogenies. Here we report the evolution of ribosomal protein S4 in relation to a broad sharing of zinc/non-zinc forms of the gene and study the scope of horizontal gene transfer (HGT of S4 during bacterial evolution. Results In this study we present the complex evolutionary history of ribosomal protein S4 using 660 bacterial genomes from 16 major bacterial phyla. According to conserved characteristics in the sequences, S4 can be classified into C+ (zinc-binding and C- (zinc-free variants, with 26 genomes (mainly from the class Clostridia containing genes for both. A maximum likelihood phylogenetic tree of the S4 sequences was incongruent with the standard bacterial phylogeny, indicating a departure from strict vertical inheritance. Further analysis using the genome content near the S4 genes, which are usually located in a conserved gene cluster, showed not only that HGT of the C- gene had occurred at various stages of bacterial evolution, but also that both the C- and C+ genes were present before the individual phyla diverged. To explain the latter, we theorize that a gene pool existed early in bacterial evolution from which bacteria could sample S4 gene variants, according to environmental conditions. The distribution of the C+/- variants for seven other zinc-binding ribosomal proteins in these 660 bacterial genomes is consistent with that seen for S4 and may shed light on the evolutionary pressures involved. Conclusion The complex history presented for "core" protein S4 suggests the existence of a gene pool before the emergence of bacterial lineages and reflects the pervasive nature of HGT in subsequent bacterial evolution

  16. Molecular methods for bacterial genotyping and analyzed gene regions

    Directory of Open Access Journals (Sweden)

    İbrahim Halil Yıldırım1, Seval Cing Yıldırım2, Nadir Koçak3

    2011-06-01

    Full Text Available Bacterial strain typing is an important process for diagnosis, treatment and epidemiological investigations. Current bacterial strain typing methods may be classified into two main categories: phenotyping and genotyping. Phenotypic characters are the reflection of genetic contents. Genotyping, which refers discrimination of bacterial strains based on their genetic content, has recently become widely used for bacterial strain typing. The methods already used in genotypingof bacteria are quite different from each other. In this review we tried to summarize the basic principles of DNA-based methods used in genotyping of bacteria and describe some important DNA regions that are used in genotyping of bacteria. J Microbiol Infect Dis 2011;1(1:42-46.

  17. Role of Streptococcus pyogenes Two-Component Response Regulators in the Temporal Control of Mga and the Mga-Regulated Virulence Gene emm

    OpenAIRE

    Ribardo, Deborah A.; Lambert, Thomas J.; McIver, Kevin S.

    2004-01-01

    We examined the role of Streptococcus pyogenes two-component response regulators (SptR) in expression of Mga and the Mga-regulated gene emm. Both serotype M6 and serotype M1 mutants in 12 of the 13 identified sptR genes exhibited levels of emm transcripts and Mga protein comparable to those of the wild type during exponential and stationary phases of growth. Thus, temporal control of these virulence genes does not require Spt response regulators.

  18. Comparative analysis of agr groups and virulence genes among subclinical and clinical mastitis Staphylococcus aureus isolates from sheep flocks of the Northeast of Brazil

    OpenAIRE

    de Almeida, Lara M.; de Almeida, Mayra Zilta P.R.B.; Carla L. Mendonça; Mamizuka, Elsa M.

    2013-01-01

    Staphylococcus aureus is one of the most frequent mastitis causative agents in small ruminants. The expression of most virulence genes of S. aureus is controlled by an accessory gene regulator (agr) locus. This study aimed to ascertain the prevalence of the different agr groups and to evaluate the occurrence of encoding genes for cytotoxin, adhesins and toxins with superantigen activity in S. aureus isolates from milk of ewes with clinical and subclinical mastitis in sheep flocks raised for m...

  19. A non-coding RNA promotes bacterial persistence and decreases virulence by regulating a regulator in Staphylococcus aureus.

    Directory of Open Access Journals (Sweden)

    Cédric Romilly

    2014-03-01

    Full Text Available Staphylococcus aureus produces a high number of RNAs for which the functions are poorly understood. Several non-coding RNAs carry a C-rich sequence suggesting that they regulate mRNAs at the post-transcriptional level. We demonstrate that the Sigma B-dependent RsaA RNA represses the synthesis of the global transcriptional regulator MgrA by forming an imperfect duplex with the Shine and Dalgarno sequence and a loop-loop interaction within the coding region of the target mRNA. These two recognition sites are required for translation repression. Consequently, RsaA causes enhanced production of biofilm and a decreased synthesis of capsule formation in several strain backgrounds. These phenotypes led to a decreased protection of S. aureus against opsonophagocytic killing by polymorphonuclear leukocytes compared to the mutant strains lacking RsaA. Mice animal models showed that RsaA attenuates the severity of acute systemic infections and enhances chronic catheter infection. RsaA takes part in a regulatory network that contributes to the complex interactions of S. aureus with the host immune system to moderate invasiveness and favour chronic infections. It is the first example of a conserved small RNA in S. aureus functioning as a virulence suppressor of acute infections. Because S. aureus is essentially a human commensal, we propose that RsaA has been positively selected through evolution to support commensalism and saprophytic interactions with the host.

  20. The Transcriptional Regulator RovS Controls the Attachment of Streptococcus agalactiae to Human Epithelial Cells and the Expression of Virulence Genes

    OpenAIRE

    Samen, Ulrike M.; Eikmanns, Bernhard J.; Reinscheid, Dieter J.

    2006-01-01

    Streptococcus agalactiae is part of the normal flora of the human gastrointestinal tract and also the leading cause of bacterial infections in human newborns and immunocompromised adults. The colonization and infection of different regions within the human host require a regulatory network in S. agalactiae that senses environmental stimuli and controls the formation of specific virulence factors. In the present study, we characterized an Rgg-like transcriptional regulator, designated RovS (re...

  1. Molecular analysis of virulent genes (coa and spa) of staphylococcus aureus involved in natural cases of bovine mastitis

    International Nuclear Information System (INIS)

    The present study was undertaken to determine the distribution and genotypic characteristics of Staphylococcus aureus isolates recovered from naturally occurring mastitis in cattle and buffaloes. For this purpose a total of 1445 lactating cattle (653) and buffaloes (792) present at two experimental livestock farms Okara (Bahadarnagar) and Sahiwal (Qadiarabad), in and around district Faisalabad and slaughtered at an abattoir due to low milk yield and were screened for mastitis. California Mastitis Test (CMT) was used to detect sub clinical mastitis. The positive quarter milk samples were collected for culturing of S. aureus isolates. taphylococcus aureus isolates were identified on the basis of growth features, biochemical characteristics, coagulase test and as well as amplification of coagulase (coa) and spa (spa-X) genes specific to its virulence. S. aureus isolates (n=265) were characterized by Polymerase chain reaction to determine the frequency of coagulase (coa) and spa (spa-X) genes. From these isolates the amplification of the coagulase (coa) gene yielded three different PCR products approximately 204bp to 490bp while spa (spa-X) gene produced five different products ranging in size from 190bp to 320bp. PCR revealed that from all the coagulase positive S. aureus isolates 261(98.5%) had spa (spa-X) gene. The results of the present study indicated that S. aureus isolates recovered from bovine mastitis were genetically different within and among the various herds which may provide essential and valuable strategies to control staphylococcal infections in future. (author)

  2. Identification of Genes Induced in Lolium multiflorum by Bacterial Wilt Infection

    DEFF Research Database (Denmark)

    Wichmann, Fabienne; Asp, Torben; Widmer, Franco; Kölliker, Roland

    Xanthomonas translucens pv. graminis(Xtg) causes bacterial wilt in many forage grasses including Italian ryegrass (Lolium multiflorum Lam), seriously reducing yield and quality. Breeding for resistance is currently the only practicable means of disease control. Molecular markers closely linked to...... resistance genes or QTL could complement and support phenotypic selection. We used comparative gene expression analysis of a partially resistant L. multiflorum genotype infected and not infected with Xtg to identify genes involved in the control of resistance to bacterial wilt. The genes differentially...... expressed upon infection will serve as the basis for the identification of key genes involved in bacterial wilt resistance and to develop molecular markers for marker assisted breeding. Fluorescently labelled cDNA prepared from plant leaves collected at four different time points after infection was...

  3. The host metabolite D-serine contributes to bacterial niche specificity through gene selection

    OpenAIRE

    Connolly, James P. R.; Goldstone, Robert J.; Burgess, Karl; Cogdell, Richard J.; Beatson, Scott A.; Vollmer, Waldemar; Smith, David G. E.; Roe, Andrew

    2015-01-01

    Escherichia coli comprise a diverse array of both commensals and niche-specific pathotypes. The ability to cause disease results from both carriage of specific virulence factors and regulatory control of these via environmental stimuli. Moreover, host metabolites further refine the response of bacteria to their environment and can dramatically affect the outcome of the host–pathogen interaction. Here, we demonstrate that the host metabolite, D-serine, selectively affects gene expression in E....

  4. The Daiokanzoto (TJ-84 Kampo Formulation Reduces Virulence Factor Gene Expression in Porphyromonas gingivalis and Possesses Anti-Inflammatory and Anti-Protease Activities.

    Directory of Open Access Journals (Sweden)

    Jade Fournier-Larente

    Full Text Available Kampo formulations used in Japan to treat a wide variety of diseases and to promote health are composed of mixtures of crude extracts from the roots, bark, leaves, and rhizomes of a number of herbs. The present study was aimed at identifying the beneficial biological properties of Daiokanzoto (TJ-84, a Kampo formulation composed of crude extracts of Rhubarb rhizomes and Glycyrrhiza roots, with a view to using it as a potential treatment for periodontal disease. Daiokanzoto dose-dependently inhibited the expression of major Porphyromonas gingivalis virulence factors involved in host colonization and tissue destruction. More specifically, Daiokanzoto reduced the expression of the fimA, hagA, rgpA, and rgpB genes, as determined by quantitative real-time PCR. The U937-3xκB-LUC monocyte cell line transfected with a luciferase reporter gene was used to evaluate the anti-inflammatory properties of Daiokanzoto. Daiokanzoto attenuated the P. gingivalis-mediated activation of the NF-κB signaling pathway. It also reduced the secretion of pro-inflammatory cytokines (IL-6 and CXCL8 by lipopolysaccharide-stimulated oral epithelial cells and gingival fibroblasts. Lastly, Daiokanzoto, dose-dependently inhibited the catalytic activity of matrix metalloproteinases (-1 and -9. In conclusion, the present study provided evidence that Daiokanzoto shows potential for treating and/or preventing periodontal disease. The ability of this Kampo formulation to act on both bacterial pathogens and the host inflammatory response, the two etiological components of periodontal disease, is of high therapeutic interest.

  5. The Daiokanzoto (TJ-84) Kampo Formulation Reduces Virulence Factor Gene Expression in Porphyromonas gingivalis and Possesses Anti-Inflammatory and Anti-Protease Activities.

    Science.gov (United States)

    Fournier-Larente, Jade; Azelmat, Jabrane; Yoshioka, Masami; Hinode, Daisuke; Grenier, Daniel

    2016-01-01

    Kampo formulations used in Japan to treat a wide variety of diseases and to promote health are composed of mixtures of crude extracts from the roots, bark, leaves, and rhizomes of a number of herbs. The present study was aimed at identifying the beneficial biological properties of Daiokanzoto (TJ-84), a Kampo formulation composed of crude extracts of Rhubarb rhizomes and Glycyrrhiza roots, with a view to using it as a potential treatment for periodontal disease. Daiokanzoto dose-dependently inhibited the expression of major Porphyromonas gingivalis virulence factors involved in host colonization and tissue destruction. More specifically, Daiokanzoto reduced the expression of the fimA, hagA, rgpA, and rgpB genes, as determined by quantitative real-time PCR. The U937-3xκB-LUC monocyte cell line transfected with a luciferase reporter gene was used to evaluate the anti-inflammatory properties of Daiokanzoto. Daiokanzoto attenuated the P. gingivalis-mediated activation of the NF-κB signaling pathway. It also reduced the secretion of pro-inflammatory cytokines (IL-6 and CXCL8) by lipopolysaccharide-stimulated oral epithelial cells and gingival fibroblasts. Lastly, Daiokanzoto, dose-dependently inhibited the catalytic activity of matrix metalloproteinases (-1 and -9). In conclusion, the present study provided evidence that Daiokanzoto shows potential for treating and/or preventing periodontal disease. The ability of this Kampo formulation to act on both bacterial pathogens and the host inflammatory response, the two etiological components of periodontal disease, is of high therapeutic interest. PMID:26859747

  6. Phenotypes Associated with Knockouts of Eight Dense Granule Gene Loci (GRA2-9) in Virulent Toxoplasma gondii.

    Science.gov (United States)

    Rommereim, Leah M; Bellini, Valeria; Fox, Barbara A; Pètre, Graciane; Rak, Camille; Touquet, Bastien; Aldebert, Delphine; Dubremetz, Jean-François; Cesbron-Delauw, Marie-France; Mercier, Corinne; Bzik, David J

    2016-01-01

    Toxoplasma gondii actively invades host cells and establishes a parasitophorous vacuole (PV) that accumulates many proteins secreted by the dense granules (GRA proteins). To date, at least 23 GRA proteins have been reported, though the function(s) of most of these proteins still remains unknown. We targeted gene knockouts at ten GRA gene loci (GRA1-10) to investigate the cellular roles and essentiality of these classical GRA proteins during acute infection in the virulent type I RH strain. While eight of these genes (GRA2-9) were successfully knocked out, targeted knockouts at the GRA1 and GRA10 loci were not obtained, suggesting these GRA proteins may be essential. As expected, the Δgra2 and Δgra6 knockouts failed to form an intravacuolar network (IVN). Surprisingly, Δgra7 exhibited hyper-formation of the IVN in both normal and lipid-free growth conditions. No morphological alterations were identified in parasite or PV structures in the Δgra3, Δgra4, Δgra5, Δgra8, or Δgra9 knockouts. With the exception of the Δgra3 and Δgra8 knockouts, all of the GRA knockouts exhibited defects in their infection rate in vitro. While the single GRA knockouts did not exhibit reduced replication rates in vitro, replication rate defects were observed in three double GRA knockout strains (Δgra4Δgra6, Δgra3Δgra5 and Δgra3Δgra7). However, the virulence of single or double GRA knockout strains in CD1 mice was not affected. Collectively, our results suggest that while the eight individual GRA proteins investigated in this study (GRA2-9) are not essential, several GRA proteins may provide redundant and potentially important functions during acute infection. PMID:27458822

  7. Molecular characterization and virulence gene profiling of pathogenic Streptococcus agalactiae populations from tilapia (Oreochromis sp.) farms in Thailand.

    Science.gov (United States)

    Kayansamruaj, Pattanapon; Pirarat, Nopadon; Katagiri, Takayuki; Hirono, Ikuo; Rodkhum, Channarong

    2014-05-19

    Streptococcus spp. were recovered from diseased tilapia in Thailand during 2009-2010 (n = 33), and were also continually collected from environmental samples (sediment and water) from tilapia farms for 9 months in 2011 (n = 25). The relative percent recovery of streptococci from environmental samples was 13-67%. All streptococcal isolates were identified as S. agalactiae (group B streptococci [GBS]) by a species-specific polymerase chain reaction. In molecular characterization assays, 4 genotypic categories comprised of 1) molecular serotypes, 2) the infB allele, 3) virulence gene profiling patterns (cylE, hylB, scpB, lmb, cspA, dltA, fbsA, fbsB, bibA, gap, and pili backbone-encoded genes), and 4) randomly amplified polymorphic DNA (RAPD) fingerprinting patterns, were used to describe the genotypic diversity of the GBS isolates. There was only 1 isolate identified as molecular serotype III, while the others were serotype Ia. Most GBS serotype Ia isolates had an identical infB allele and virulence gene profiling patterns, but a large diversity was established by RAPD analysis with diversity tending to be geographically dependent. Experimental infection of Nile tilapia (Oreochromis niloticus) revealed that the GBS serotype III isolate was nonpathogenic in the fish, while all 5 serotype Ia isolates (3 fish and 2 environmental isolates) were pathogenic, with a median lethal dose of 6.25-7.56 log10 colony-forming units. In conclusion, GBS isolates from tilapia farms in Thailand showed a large genetic diversity, which was associated with the geographical origins of the bacteria. PMID:24842288

  8. Prevalence of serogroups and virulence genes in Escherichia coli associated with postweaning diarrhoea and edema disease in pigs and a comparison of diagnostic approaches

    DEFF Research Database (Denmark)

    Frydendahl, K.

    2002-01-01

    Identification of Escherichia coli causing porcine postweaning diarrhoea (PWD) or edema disease (ED) requires knowledge regarding the prevalent pathotypes within a given region. This study was undertaken to determine the present distribution of serogroups. hemolytic activity and virulence factor.......7%). Hemolytic activity was detected in 87.7%, of all isolates. Virulence factor genes detected were F4 (44.7%), F18 (39.3%). intimin ( 1.4%), F6 (0.9%), STb (77.6%), EAST1 (65.8%). LT (61.6%), STa (26.5%) and Me (16.4%). Six pathotypes accounted for 65.7% of all isolates investigated. Using possession of...... virulence factor genes as reference, O-serogrouping employing a selection of antisera representing common pig pathogenic serogroups and detection of hemolysis were evaluated as epidemiological markers for pathogenicity. Both criteria were associated with pathogenicity (P <0.001. for both), however, both...

  9. Cell Density Control of Staphylococcal Virulence Mediated by an Octapeptide Pheromone

    Science.gov (United States)

    Ji, Guangyong; Beavis, Ronald C.; Novick, Richard P.

    1995-12-01

    Some bacterial pathogens elaborate and secrete virulence factors in response to environmental signals, others in response to a specific host product, and still others in response to no discernible cue. In this study, we have demonstrated that the synthesis of Staphylococcus aureus virulence factors is controlled by a density-sensing system that utilizes an octapeptide produced by the organism itself. The octapeptide activates expression of the agr locus, a global regulator of the virulence response. This response involves the reciprocal regulation of genes encoding surface proteins and those encoding secreted virulence factors. As cells enter the postexponential phase, surface protein genes are repressed by agr and secretory protein genes are subsequently activated. The intracellular agr effector is a regulatory RNA, RNAIII, whose transcription is activated by an agr-encoded signal transduction system for which the octapeptide is the ligand.

  10. Prevalence of the Most Common Virulence-Associated Genes among Brucella Melitensis Isolates from Human Blood Cultures in Hamadan Province, West of Iran.

    Science.gov (United States)

    Naseri, Zahra; Alikhani, Mohammad Yousef; Hashemi, Seyed Hamid; Kamarehei, Farideh; Arabestani, Mohammad Reza

    2016-09-01

    Brucellosis is a widespread zoonotic disease causing considerable economic and public health problems. Despite animal vaccination, brucellosis remains endemic in some areas such as Iran, especially in the western Iranian province of Hamadan. We sought to detect some of the most common virulence-associated genes in Brucella isolated from human blood cultures to determine the prevalence of some virulence genes among Brucella isolates. Fifty-seven isolates were studied from patients with a clinical diagnosis of brucellosis who referred to the Infectious Diseases Ward of Sina Hospital in Hamadan Province, Iran, between April 2013 and July 2014. Blood samples were collected for the diagnosis of brucellosis using the BACTEC blood culture system. All of these isolates were confirmed by the bcsp31 Brucella-specific gene. We detected 11 virulence-associated genes of Brucella, namely cβg, virB, znuA, ure, bvfA, omp25, omp31, wbkA, mviN, manA, and manB, which are important for the pathogenesis of this bacterium in the intracellular environment by multiplex PCR. Totally, 149 patients with a clinical diagnosis of brucellosis were enrolled in this study. Fifty-seven (38.3%) patients had positive blood cultures. On biochemical and molecular testing, all of the isolates were Brucella melitensis. Ten of the virulence genes were detected among all of the 57 isolates, but the bvf gene was detected in 53 (93%) isolates. The high prevalence of virulence-associated genes among the Brucella isolates detected in Hamadan Province, Iran, underscores the pathogenicity of this bacterium in this region. PMID:27582592

  11. Expression of Virulence-Related Genes in Listeria monocytogenes Grown on Danish Hard Cheese as Affected by NaCl Content.

    Science.gov (United States)

    Larsen, Nadja; Jespersen, Lene

    2015-06-01

    Expression of virulence-related genes in Listeria monocytogenes incubated on cheese was assessed by real-time quantitative polymerase chain reaction. The objective of the study was to investigate the impact of sodium chloride concentration in cheese on transcription of virulence genes and, thereby, virulence potential of L. monocytogenes. The expression studies were performed with L. monocytogenes strains characterized by different tolerance to salt stress. Strains ATCC(®) 51779 and DSMZ 15675 were incubated on the Danish hard-cheese type Samsoe, with low (<0.15% [wt/wt]) and high (3.6% [wt/wt]) content of NaCl. Genes differentially expressed (p<0.05) through the 48-h incubation were transcriptional regulators prfA and agrA, genes of the main virulence cluster inlA, hly, actA, involved in invasion of the epithelial cells, and genes bsh, opuC, gadC, clpP, and ami, associated with osmotic stress responses in L. monocytogenes. The more sensitive strain ATCC(®) 51779 was most responsive, showing significant upregulation of prfA, actA, hly, and bsh both at low and high NaCl. Strain DSMZ 15675 was less responsive to NaCl stress, showing reduced or consistent gene transcription at all conditions. Decreased transcription of agrA, ami, gadC, and opuC in both strains was promoted by low NaCl content. The study indicated that virulence gene expression of L. monocytogenes grown in cheese was affected by NaCl content and that effect was more significant in strains sensitive to both hypo- and hyperosmotic stresses. PMID:26067229

  12. CHARACTERIZATION OF VIRULENCE GENES AND ANTIMICROBIAL RESISTANCE OF LUNG PATHOGENIC ESCHERICHIA COLI ISOLATES IN FOREST MUSK DEER (MOSCHUS BEREZOVSKII).

    Science.gov (United States)

    Luo, Xi; Wang, Peng; Cheng, Jian-guo; Luo, Yan; Dai, Lei; Zhou, Xin; Zou, Li-kou; Li, Bei; Xiao, Jiu-Jin

    2016-06-01

    This study investigated genotypic diversity, 26 virulence genes, and antimicrobial susceptibility of lung pathogenic Escherichia coli (LPEC) isolated from forest musk deer. Associations between virulence factors (VFs) and phylogenetic group, between antimicrobial resistance (AMR) and phylogenetic group, and between AMR and VFs were subsequently assessed. The results showed 30 LPEC isolated were grouped into seven different clusters (A, B, C, D, E, F, and G). The detection rates of crl (90%), kpsMT II (76.67%), mat (76.67%), and ompA (80%) were over 75%. The most frequent types of resistance were to amoxicillin (100%), sulfafurazole (100%), ampicillin (96.67%), and tetracycline (96.67%), with 93.33% (n = 28) of isolates resistant to more than eight types of drugs. There were significant relationships between resistance to cefalotin and the presence of iucD(a) (P < 0.001), papC (P = 0.032), and kpsMT II (P = 0.028); between resistance to chloromycetin and the presence of irp2 (P = 0.004) and vat (P = 0.047); between resistance to nalidixic acid and the presence of crl (P = 0.002) and iucD(a) (P = 0.004); and between resistance to ampicillin/sulbactam and the presence of vat (P = 0.013). These results indicated there could be some association between resistance and VFs, and there is a great need for the prudent use of antimicrobial agents in LPEC. PMID:27468027

  13. Comparative profiling of the transcriptional response to iron restriction in six serotypes of Actinobacillus pleuropneumoniae with different virulence potential

    DEFF Research Database (Denmark)

    Schou, Kirstine Klitgaard; Friis, Carsten; Angen, Øystein;

    2011-01-01

    receptor of Neisseria meningitidis, a possible virulence factor which contributes to bacterial survival in rats. Conclusions By comparative analysis of gene expression among 6 different serotypes of A. pleuropneumoniae we identified a common set of presumably essential core genes, involved in iron......Background Comparative analysis of gene expression among serotypes within a species can provide valuable information on important differences between related genomes. For the pig lung pathogen Actinobacillus pleuropneumoniae, 15 serotypes with a considerable variation in virulence potential and...... virulence genes. We used a pan-genomic microarray to study the transcriptional response to iron restriction in vitro in six serotypes of A. pleuropneumoniae (1, 2, 3, 5b, 6, and 7), representing at least two levels of virulence. Results In total, 45 genes were significantly (p <0.0001) up-regulated and 67...

  14. Specific changes in the Arabidopsis proteome in response to bacterial challenge: differentiating basal and R-gene mediated resistance.

    Science.gov (United States)

    Jones, Alexandra M E; Thomas, Vincent; Truman, Bill; Lilley, Kathryn; Mansfield, John; Grant, Murray

    2004-06-01

    Alterations in the proteome of Arabidopsis thaliana leaves during early responses to challenge by Pseudomonas syringae pv. tomato DC3000 (DC3000) were analysed using two-dimensional (2D) gel electrophoresis. Protein changes characteristic of the establishment of basal resistance and R-gene mediated resistance were examined by comparing responses to DC3000, a hrp mutant and DC3000 expressing avrRpm1 respectively. The abundance of selected transcripts was also analysed in GeneChip experiments. Here we present data from the soluble fraction of leaf protein, highlighting changes in two antioxidant enzyme groups; the glutathione S-transferases (GSTs F2, F6, F7 and F8) and peroxiredoxins (PrxA, B and IIE). Members of both enzyme groups showed signs of specific post-translational modifications, represented by multiple spots on gels. We suggest that oxidation of specific residues is responsible for some of the spot shifts. All forms of the GST proteins identified here increased following inoculation with bacteria. GSTF8 showed particularly dynamic responses to pathogen challenge, the corresponding transcript was significantly up-regulated by 2 h after inoculation, and the protein showed post-translational modifications specific to an incompatible interaction. Differential changes were observed with the peroxiredoxin proteins; PrxIIE and to a lesser extent PrxB, no change was observed with PrxA, but a truncated form PrxA-L was greatly reduced in abundance following bacterial challenges. Our data suggest that bacterial challenge generally induces Prxs and the antioxidants GSTs, however individual members of these families may be specifically modified dependent upon the virulence of the DC3000 strain and outcome of the interaction. Finally, proteomic and transcriptomic data derived from the same inoculation system are compared and the advantages offered by 2D gel analysis discussed in light of our results. PMID:15276439

  15. Deletion analysis of two tandemly arranged virulence genes in myxoma virus, M11L and myxoma growth factor.

    OpenAIRE

    Opgenorth, A; Graham, K.; N. Nation; Strayer, D; McFadden, G

    1992-01-01

    Myxoma virus (MYX) is a leporipoxvirus of rabbits that induces a lethal syndrome characterized by disseminated tumorlike lesions, generalized immunosuppression, and secondary gram-negative bacterial infection. A MYX deletion mutant (vMYX-GF- delta M11L) was constructed to remove the entire myxoma growth factor (MGF) coding sequence and that for the C-terminal five amino acids of the partially overlapping upstream gene, M11L. Unexpectedly, this deletion completely abrogates the capacity of MYX...

  16. Epigenetic Control of Virulence Gene Expression in Pseudomonas aeruginosa by a LysR-Type Transcription Regulator

    OpenAIRE

    Turner, Keith H.; Isabelle Vallet-Gely; Dove, Simon L.

    2009-01-01

    Phenotypic variation within an isogenic bacterial population is thought to ensure the survival of a subset of cells in adverse conditions. The opportunistic pathogen Pseudomonas aeruginosa variably expresses several phenotypes, including antibiotic resistance, biofilm formation, and the production of CupA fimbriae. Here we describe a previously unidentified bistable switch in P. aeruginosa. This switch controls the expression of a diverse set of genes, including aprA, which encodes the secret...

  17. Magnetotactic Bacterial Cages as Safe and Smart Gene Delivery Vehicles

    KAUST Repository

    Alsaiari, Shahad K.

    2016-07-27

    In spite of the huge advances in the area of synthetic carriers, their efficiency still poorly compares to natural vectors. Herein, we report the use of unmodified magnetotactic bacteria as a guidable delivery vehicle for DNA functionalized gold nanoparticles (AuNPs). High cargo loading is established under anaerobic conditions (bacteria is alive) through endocytosis where AuNPs are employed as transmembrane proteins mimics (facilitate endocytosis) as well as imaging agents to verify and quantify loading and release. The naturally bio-mineralized magnetosomes, within the bacteria, induce heat generation inside bacteria through magnetic hyperthermia. Most importantly after exposing the system to air (bacteria is dead) the cell wall stays intact providing an efficient bacterial vessel. Upon incubation with THP-1 cells, the magnetotactic bacterial cages (MBCs) adhere to the cell wall and are directly engulfed through the phagocytic activity of these cells. Applying magnetic hyperthermia leads to the dissociation of the bacterial microcarrier and eventual release of cargo.

  18. Real-time PCR expression profiling of genes encoding potential virulence factors in Candida albicans biofilms: identification of model-dependent and -independent gene expression

    Directory of Open Access Journals (Sweden)

    Řičicová Markéta

    2010-04-01

    Full Text Available Abstract Background Candida albicans infections are often associated with biofilm formation. Previous work demonstrated that the expression of HWP1 (hyphal wall protein and of genes belonging to the ALS (agglutinin-like sequence, SAP (secreted aspartyl protease, PLB (phospholipase B and LIP (lipase gene families is associated with biofilm growth on mucosal surfaces. We investigated using real-time PCR whether genes encoding potential virulence factors are also highly expressed in biofilms associated with abiotic surfaces. For this, C. albicans biofilms were grown on silicone in microtiter plates (MTP or in the Centres for Disease Control (CDC reactor, on polyurethane in an in vivo subcutaneous catheter rat (SCR model, and on mucosal surfaces in the reconstituted human epithelium (RHE model. Results HWP1 and genes belonging to the ALS, SAP, PLB and LIP gene families were constitutively expressed in C. albicans biofilms. ALS1-5 were upregulated in all model systems, while ALS9 was mostly downregulated. ALS6 and HWP1 were overexpressed in all models except in the RHE and MTP, respectively. The expression levels of SAP1 were more pronounced in both in vitro models, while those of SAP2, SAP4 and SAP6 were higher in the in vivo model. Furthermore, SAP5 was highly upregulated in the in vivo and RHE models. For SAP9 and SAP10 similar gene expression levels were observed in all model systems. PLB genes were not considerably upregulated in biofilms, while LIP1-3, LIP5-7 and LIP9-10 were highly overexpressed in both in vitro models. Furthermore, an elevated lipase activity was detected in supernatans of biofilms grown in the MTP and RHE model. Conclusions Our findings show that HWP1 and most of the genes belonging to the ALS, SAP and LIP gene families are upregulated in C. albicans biofilms. Comparison of the fold expression between the various model systems revealed similar expression levels for some genes, while for others model-dependent expression

  19. Methicillin-resistant Staphylococcus aureus in cows with mastitis, the presence of the mecA gene and the gene for virulence

    Directory of Open Access Journals (Sweden)

    Vesna Jaki Tkalec

    2015-11-01

    Full Text Available The physiological properties of 47 Staphylococcus aureus strains were investigated. The test strains were grown on bacteriological media and identified by the ID32 STAF system for biochemical identification of bacteria. Sensitivity to antimicrobial agents was performed by the disc diffusion method. The nuc gene and the virulence factors coa, hla, hlb, hld, hlg, hlg-2, tst, eta, etb, lukF-PV and lukS-PV and mecA gene were detected by the polymerase chain reaction. Furthermore, the spa type of the studied isolates was also set. According to the obtained results, all strains had the nuc, coa, hla and hld gene. Ten strains (21.3 % had also the tst gene, while 37 strains (78.7 % had the hlg gene and 35 strains (74.5 % had the hlb and hlg-2 genes. All of the investigated S. aureus isolates were penicillin resistant (100 %, with 29 strains which were also resistant to oxacillin (61.7 %. Methicillin (oxacillin resistance was detected by the mecA gene detection, which is also the first MRSA result from the secretion samples of cows’ mammary glands in Croatia. The researched MRSA strains proved to belong to different spa types, and the most common were spa types t005, t011 and t521, and a new spa type t9498 was detected.

  20. Evolution of genes on the Salmonella Virulence plasmid phylogeny revealed from sequencing of the virulence plasmids of S. enterica serotype Dublin and comparative analysis.

    Science.gov (United States)

    Chu, Chishih; Feng, Ye; Chien, An-Chi; Hu, Songnian; Chu, Chi-Hong; Chiu, Cheng-Hsun

    2008-11-01

    Salmonella enterica serotype Dublin harbors an approximately 80-kb virulence plasmid (pSDV), which mediates systemic infection in cattle. There are two types of pSDV: one is pSDVu (pOU1113) in strain OU7025 and the other pSDVr (pOU1115) in OU7409 (SD Lane) and many clinical isolates. Sequence analysis showed that pSDVr was a recombinant plasmid (co-integrate) of pSDVu and a plasmid similar to a 35-kb indigenous plasmid (pOU1114) of S. Dublin. Most of the F-transfer region in pSDVu was replaced by a DNA segment from the pOU1114-like plasmid containing an extra replicon and a pilX operon encoding for a type IV secretion system to form pSDVr. We reconstructed the particular evolutionary history of the seven virulence plasmids of Salmonella by comparative sequence analysis. The whole evolutionary process might begin with two different F-like plasmids (IncFI and IncFII), which then incorporated the spv operon and fimbriae operon from the chromosome to form the primitive virulence plasmids. Subsequently, these plasmids descended by deletion from a relatively large plasmid to smaller ones, with some recombination events occurring over time. Our results suggest that the phylogeny of virulence plasmids as a result of frequent recombination provides the opportunity for rapid evolution of Salmonella in response to the environmental cues. PMID:18718522

  1. Seasonal changes in nitrogen-cycle gene abundances and in bacterial communities in acidic forest soils.

    Science.gov (United States)

    Jung, Jaejoon; Yeom, Jinki; Han, Jiwon; Kim, Jisun; Park, Woojun

    2012-06-01

    The abundance of genes related to the nitrogen biogeochemical cycle and the microbial community in forest soils (bacteria, archaea, fungi) were quantitatively analyzed via real-time PCR using 11 sets of specific primers amplifying nifH, bacterial amoA, archaeal amoA, narG, nirS, nirK, norB, nosZ, bacterial 16S rRNA gene, archaeal 16S rRNA gene, and the ITS sequence of fungi. Soils were sampled from Bukhan Mountain from September of 2010 to July of 2011 (7 times). Bacteria were the predominant microbial community in all samples. However, the abundance of archaeal amoA was greater than bacterial amoA throughout the year. The abundances of nifH, nirS, nirK, and norB genes changed in a similar pattern, while narG and nosZ appeared in sensitive to the environmental changes. Clone libraries of bacterial 16S rRNA genes were constructed from summer and winter soil samples and these revealed that Acidobacteria was the most predominant phylum in acidic forest soil environments in both samples. Although a specific correlation of environmental factor and gene abundance was not verified by principle component analysis, our data suggested that the combination of biological, physical, and chemical characteristics of forest soils created distinct conditions favoring the nitrogen biogeochemical cycle and that bacterial communities in undisturbed acidic forest soils were quite stable during seasonal change. PMID:22752898

  2. Detection of Shiga toxin variants, virulence genes and the relationship to cytotoxicity in Shiga toxin-producing Escherichia coli (STEC) from domestic farm animals

    Science.gov (United States)

    Shiga toxin-producing Escherichia coli (STEC) can cause foodborne illnesses ranging from diarrhea to life-threating diseases such as hemorrhagic colitis, and hemolytic uremic syndrome in humans. In this study, we determined virulence genes, stx subtypes and we evaluated the cytotoxicity in STEC stra...

  3. Characterization of shiga toxin-producing Escherichia coli recovered from domestic animals to determine stx variants, virulence genes, and cytotoxicity in mammalian cells

    Science.gov (United States)

    Shiga toxin-producing Escherichia coli (STEC) can cause foodborne illnesses ranging from diarrhea to severe diseases such as hemorrhagic colitis (HC), and hemolytic uremic syndrome (HUS) in humans. In this study, we determined virulence genes, stx subtypes and we evaluated the cytotoxicity in mammal...

  4. Exploring the relationship between fractal features and bacterial essential genes

    Science.gov (United States)

    Yong-Ming, Yu; Li-Cai, Yang; Qian, Zhou; Lu-Lu, Zhao; Zhi-Ping, Liu

    2016-06-01

    Essential genes are indispensable for the survival of an organism in optimal conditions. Rapid and accurate identifications of new essential genes are of great theoretical and practical significance. Exploring features with predictive power is fundamental for this. Here, we calculate six fractal features from primary gene and protein sequences and then explore their relationship with gene essentiality by statistical analysis and machine learning-based methods. The models are applied to all the currently available identified genes in 27 bacteria from the database of essential genes (DEG). It is found that the fractal features of essential genes generally differ from those of non-essential genes. The fractal features are used to ascertain the parameters of two machine learning classifiers: Naïve Bayes and Random Forest. The area under the curve (AUC) of both classifiers show that each fractal feature is satisfactorily discriminative between essential genes and non-essential genes individually. And, although significant correlations exist among fractal features, gene essentiality can also be reliably predicted by various combinations of them. Thus, the fractal features analyzed in our study can be used not only to construct a good essentiality classifier alone, but also to be significant contributors for computational tools identifying essential genes. Project supported by the Shandong Provincial Natural Science Foundation, China (Grant No. ZR2014FM022).

  5. Comparative transcript profiling of Candida albicans and Candida dubliniensis identifies SFL2, a C. albicans gene required for virulence in a reconstituted epithelial infection model.

    LENUS (Irish Health Repository)

    Spiering, Martin J

    2010-02-01

    Candida albicans and Candida dubliniensis are closely related species displaying differences in virulence and genome content, therefore providing potential opportunities to identify novel C. albicans virulence genes. C. albicans gene arrays were used for comparative analysis of global gene expression in the two species in reconstituted human oral epithelium (RHE). C. albicans (SC5314) showed upregulation of hypha-specific and virulence genes within 30 min postinoculation, coinciding with rapid induction of filamentation and increased RHE damage. C. dubliniensis (CD36) showed no detectable upregulation of hypha-specific genes, grew as yeast, and caused limited RHE damage. Several genes absent or highly divergent in C. dubliniensis were upregulated in C. albicans. One such gene, SFL2 (orf19.3969), encoding a putative heat shock factor, was deleted in C. albicans. DeltaDeltasfl2 cells failed to filament under a range of hypha-inducing conditions and exhibited greatly reduced RHE damage, reversed by reintroduction of SFL2 into the DeltaDeltasfl2 strain. Moreover, SFL2 overexpression in C. albicans triggered hyphal morphogenesis. Although SFL2 deletion had no apparent effect on host survival in the murine model of systemic infection, DeltaDeltasfl2 strain-infected kidney tissues contained only yeast cells. These results suggest a role for SFL2 in morphogenesis and an indirect role in C. albicans pathogenesis in epithelial tissues.

  6. Some virulence genes of Escherichia coli isolated from cloacal swabs of healthy Alagoas Curassows (Pauxi mitu in Brazil Alguns genes de virulência de Escherichia coli isoladas de mutuns-do-nordeste (Pauxi mitu sadios no Brasil

    Directory of Open Access Journals (Sweden)

    André A.B. Saidenberg

    2013-04-01

    Full Text Available Birds of the Cracidae family (curassows, guans, and chachalacas are endemic of the Neotropics and 50 species are currently classified. Brazil has 22 species, seven of which are considered threatened. The Alagoas Curassow (Pauxi mitu species is considered extinct in the wild; but about 120 birds are alive in captivity. Conservation of this species depends entirely on correct management. Health reports of both wildlife and captive curassows are rare. In this study the presence of Escherichia coli was evaluated in 23 healthy Alagoas Curassows from two private breeding centres. E. coli was isolated from cloacal swabs, and the presence of genes encoding cytotoxic necrotising factor 1 (cnf1, alpha-haemolysin (hly, aerobactin (iuc, serum resistance (iss and the following adhesions: S fimbriae (sfa, pili associated with pyelonephritis (pap and temperature-sensitive haemagglutinin (tsh were investigated. E. coli was isolated from 78.3% (18/23 of the birds, and the percentage of curassows colonized by E. coli was similar between the two facilities. From the 22 E. coli isolates, 15 (68.2% were positive for at least one virulence factor by PCR, and the most frequently found gene was iss (50%. No curassows had clinical signs of disease. Nevertheless, the presence of some E. coli strains may be a concern to the wildlife in captivity. Additional health surveillance studies are essential to guarantee successful conservation programmes for threatened cracids in Brazil.Aves da família Cracidae (mutuns, jacutingas e aracuãs são endêmicas da região Neotropical com 50 espécies atualmente classificadas. O Brasil possui 22 espécies nesta família e sete delas são consideradas ameaçadas de extinção. O mutum-do-nordeste (Pauxi mitu é considerado extinto na natureza, no entanto, aproximadamente 120 indivíduos são mantidos em cativeiro. A conservação desta espécie depende inteiramente de um manejo correto. Informações sobre o status sanitário de mutuns

  7. A BAC-bacterial recombination method to generate physically linked multiple gene reporter DNA constructs

    Directory of Open Access Journals (Sweden)

    Gong Shiaochin

    2009-03-01

    Full Text Available Abstract Background Reporter gene mice are valuable animal models for biological research providing a gene expression readout that can contribute to cellular characterization within the context of a developmental process. With the advancement of bacterial recombination techniques to engineer reporter gene constructs from BAC genomic clones and the generation of optically distinguishable fluorescent protein reporter genes, there is an unprecedented capability to engineer more informative transgenic reporter mouse models relative to what has been traditionally available. Results We demonstrate here our first effort on the development of a three stage bacterial recombination strategy to physically link multiple genes together with their respective fluorescent protein (FP reporters in one DNA fragment. This strategy uses bacterial recombination techniques to: (1 subclone genes of interest into BAC linking vectors, (2 insert desired reporter genes into respective genes and (3 link different gene-reporters together. As proof of concept, we have generated a single DNA fragment containing the genes Trap, Dmp1, and Ibsp driving the expression of ECFP, mCherry, and Topaz FP reporter genes, respectively. Using this DNA construct, we have successfully generated transgenic reporter mice that retain two to three gene readouts. Conclusion The three stage methodology to link multiple genes with their respective fluorescent protein reporter works with reasonable efficiency. Moreover, gene linkage allows for their common chromosomal integration into a single locus. However, the testing of this multi-reporter DNA construct by transgenesis does suggest that the linkage of two different genes together, despite their large size, can still create a positional effect. We believe that gene choice, genomic DNA fragment size and the presence of endogenous insulator elements are critical variables.

  8. Single-taxon field measurements of bacterial gene regulation controlling DMSP fate.

    Science.gov (United States)

    Varaljay, Vanessa A; Robidart, Julie; Preston, Christina M; Gifford, Scott M; Durham, Bryndan P; Burns, Andrew S; Ryan, John P; Marin, Roman; Kiene, Ronald P; Zehr, Jonathan P; Scholin, Christopher A; Moran, Mary Ann

    2015-07-01

    The 'bacterial switch' is a proposed regulatory point in the global sulfur cycle that routes dimethylsulfoniopropionate (DMSP) to two fundamentally different fates in seawater through genes encoding either the cleavage or demethylation pathway, and affects the flux of volatile sulfur from ocean surface waters to the atmosphere. Yet which ecological or physiological factors might control the bacterial switch remains a topic of considerable debate. Here we report the first field observations of dynamic changes in expression of DMSP pathway genes by a single marine bacterial species in its natural environment. Detection of taxon-specific gene expression in Roseobacter species HTCC2255 during a month-long deployment of an autonomous ocean sensor in Monterey Bay, CA captured in situ regulation of the first gene in each DMSP pathway (dddP and dmdA) that corresponded with shifts in the taxonomy of the phytoplankton community. Expression of the demethylation pathway was relatively greater during a high-DMSP-producing dinoflagellate bloom, and expression of the cleavage pathway was greater in the presence of a mixed diatom and dinoflagellate community [corrected].These field data fit the prevailing hypothesis for bacterial DMSP gene regulation based on bacterial sulfur demand, but also suggest a modification involving oxidative stress response, evidenced as upregulation of catalase via katG, when DMSP is demethylated. PMID:25700338

  9. The Global Response Regulator ExpA Controls Virulence Gene Expression through RsmA-Mediated and RsmA-Independent Pathways in Pectobacterium wasabiae SCC3193

    OpenAIRE

    Broberg, M.; G. W. Lee; Nykyri, J.; Lee, Y. H.; Pirhonen, M.; Palva, E. T.

    2014-01-01

    ExpA (GacA) is a global response regulator that controls the expression of major virulence genes, such as those encoding plant cell wall-degrading enzymes (PCWDEs) in the model soft rot phytopathogen Pectobacterium wasabiae SCC3193. Several studies with pectobacteria as well as related phytopathogenic gammaproteobacteria, such as Dickeya and Pseudomonas, suggest that the control of virulence by ExpA and its homologues is executed partly by modulating the activity of RsmA, an RNA-binding postt...

  10. Co2+-dependent gene expression in Streptococcus pneumoniae: opposite effect of Mn2+ and Co2+ on the expression of the virulence genes psaBCA, pcpA, and prtA

    NARCIS (Netherlands)

    Manzoor, Irfan; Shafeeq, Sulman; Kloosterman, Tomas; Kuipers, Oscar

    2015-01-01

    Manganese (Mn2+)-, zinc (Zn2+)- and copper (Cu2+) play significant roles in transcriptional gene regulation, physiology, and virulence of Streptococcus pneumoniae. So far, the effect of the important transition metal ion cobalt (Co2+) on gene expression of S. pneumoniae has not yet been explored. He

  11. Virulence of a Porphyromonas gingivalis W83 mutant defective in the prtH gene.

    OpenAIRE

    Fletcher, H M; Schenkein, H A; Morgan, R M; Bailey, K. A.; Berry, C. R.; Macrina, F L

    1995-01-01

    In a previous study we cloned and determined the nucleotide sequence of the prtH gene from Porphyromonas gingivalis W83. This gene specifies a 97-kDa protease which is normally found in the membrane vesicles produced by P. gingivalis and which cleaves the C3 complement protein under defined conditions. We developed a novel ermF-ermAM antibiotic resistance gene cassette, which was used with the cloned prtH gene to prepare an insertionally inactivated allele of this gene. This genetic construct...

  12. Progress on Virulence Factor and Virulence Gene Research of Vibrio alginolytic%溶藻弧菌的毒力因子与相关基因的研究进展

    Institute of Scientific and Technical Information of China (English)

    梅冰; 陆翔; 王丽娜; 王永乔; 窦法楷; 汪慧莲; 李显秋

    2015-01-01

    Vibrio alginolyticus is one of the normal microorganism in the ocean,exist in a variety of marine ani-mal,fish,shrimp,shellfish and other marine aquaculture animal opportunistic pathogen.This paper briefly in-troduces the related to virulence factors and virulence of gene.%溶藻弧菌流行病学溶藻弧菌为海洋中正常菌群之一,存在于多种海洋动物中,是鱼、虾、贝等海水养殖动物的条件致病菌。简要介绍了溶藻弧菌毒力因子和毒力相关基因。

  13. 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.

  14. The Listeria monocytogenes σB Regulon and Its Virulence-Associated Functions Are Inhibited by a Small Molecule

    OpenAIRE

    Palmer, M. Elizabeth; Chaturongakul, Soraya; Wiedmann, Martin; Boor, Kathryn J.

    2011-01-01

    ABSTRACT The stress-responsive alternative sigma factor σB is conserved across diverse Gram-positive bacterial genera. In Listeria monocytogenes, σB regulates transcription of >150 genes, including genes contributing to virulence and to bacterial survival under host-associated stress conditions, such as those encountered in the human gastrointestinal lumen. An inhibitor of L. monocytogenes σB activity was identified by screening ~57,000 natural and synthesized small molecules using a high-thr...

  15. Virulence genes and neutral DNA markers of Helicobacter pylori isolates from different ethnic communities of West Bengal, India.

    Science.gov (United States)

    Datta, Simanti; Chattopadhyay, Santanu; Balakrish Nair, G; Mukhopadhyay, Asish K; Hembram, Jabaranjan; Berg, Douglas E; Rani Saha, Dhira; Khan, Asis; Santra, Amal; Bhattacharya, S K; Chowdhury, Abhijit

    2003-08-01

    Virulence-associated genes and neutral DNA markers of Helicobacter pylori strains from the Santhal and Oroan ethnic minorities of West Bengal, India, were studied. These people have traditionally been quite separate from other Indians and differ culturally, genetically, and linguistically from mainstream Bengalis, whose H. pylori strains have been characterized previously. H. pylori was found in each of 49 study participants, although none had peptic ulcer disease, and was cultured from 31 of them. All strains carried the cag pathogenicity island and potentially toxigenic s1 alleles of vacuolating cytotoxin gene (vacA) and were resistant to at least 8 micro g of metronidazole per ml. DNA sequence motifs in vacA mid-region m1 alleles, cagA, and an informative insertion or deletion motif next to cagA from these strains were similar to those of strains from ethnic Bengalis. Three mobile elements, IS605, IS607, and ISHp608, were present in 29, 19, and 10%, respectively, of Santhal and Oroan strains, which is similar to their prevalence in Bengali H. pylori. Thus, there is no evidence that the gene pools of H. pylori of these ethnic minorities differ from those of Bengalis from the same region. This relatedness of strains from persons of different ethnicities bears on our understanding of H. pylori transmission between communities and genome evolution. PMID:12904384

  16. Detection and Molecular characterisation of Virulence Genes in Antibiotic Resistant Staphylococcus aureus from milk in the North West Province, South Africa / Muyiwa Ajoke Akindolire

    OpenAIRE

    Akindolire, Muyiwa Ajoke

    2013-01-01

    Staphylococcus aureus (S. aureus) is a common microorganism present on the skin and mucosal surfaces of humans and animals. However, a variety of infections, ranging from mild skin infections to severe infections such as bacteraemia, osteomylitis, and toxin-mediated diseases can be caused by this bacterium. These infections become more severe if strain harbours antibiotic resistance genes together with virulence genes. The aim of this study was to investigate the occurrence, an...

  17. Mga Is Sufficient To Activate Transcription In Vitro of sof-sfbX and Other Mga-Regulated Virulence Genes in the Group A Streptococcus

    OpenAIRE

    Almengor, Audry C.; Walters, Matthew S; McIver, Kevin S.

    2006-01-01

    The group A streptococcus (GAS), or Streptococcus pyogenes, is a strict human pathogen of medical significance, causing infections ranging from pharyngitis (strep throat) to necrotizing fasciitis (flesh-eating disease). Several virulence genes that encode factors important for colonization, internalization, and immune evasion are under the control of the multiple gene regulator of the GAS, or Mga. Mga functions as a DNA-binding protein that interacts with sites both proximal (Pemm and PscpA) ...

  18. The spv genes on the Salmonella dublin virulence plasmid are required for severe enteritis and systemic infection in the natural host.

    OpenAIRE

    Libby, S J; Adams, L G; Ficht, T A; Allen, C.; Whitford, H A; Buchmeier, N A; Bossie, S; Guiney, D G

    1997-01-01

    The pathogenic role of the spv (Salmonella plasmid virulence) genes of Salmonella dublin was determined in the natural, bovine host. Since the lack of overt signs of enteritis or enterocolitis due to Salmonella infections in mice has limited the development of a convenient experimental system to study enteric disease, we used calves to study the contribution of the spv genes to S. dublin-induced salmonellosis. Since the SpvR transcriptional regulator is required for expression of the spvABCD ...

  19. Infection of human airway epithelial cells by different subtypes of Dobrava-Belgrade virus reveals gene expression patterns corresponding to their virulence potential.

    Science.gov (United States)

    Witkowski, Peter T; Bourquain, Daniel; Bankov, Katrin; Auste, Brita; Dabrowski, Piotr W; Nitsche, Andreas; Krüger, Detlev H; Schaade, Lars

    2016-06-01

    Dobrava-Belgrade virus (DOBV) is a pathogen causing hemorrhagic fever with renal syndrome in Europe. Virulence and case fatality rate are associated with virus genotype; however the reasons for these differences are not well understood. In this work we present virus-specific effects on the gene expression profiles of human lung epithelial cells (A549) infected with different genotypes of DOBV (Dobrava, Kurkino, and Sochi), as well as the low-virulent Tula virus (TULV). The data was collected by whole-genome gene expression microarrays and confirmed by quantitative real-time PCR. Despite their close genetic relationship, the expression profiles induced by infection with different hantaviruses are significantly varying. Major differences were observed in regulation of immune response genes, which were especially induced by highly virulent DOBV genotypes Dobrava and Sochi in contrast to less virulent DOBV-Kurkino and TULV. This work gives first insights into the differences of virus - host interactions of DOBV on genotype level. PMID:27058765

  20. The diversities of staphylococcal species, virulence and antibiotic resistance genes in the subclinical mastitis milk from a single Chinese cow herd.

    Science.gov (United States)

    Xu, Jia; Tan, Xiao; Zhang, Xinyu; Xia, Xiaoli; Sun, Huaichang

    2015-11-01

    Staphylococci are the leading pathogens of bovine mastitis which is difficult to control. However, the published data on the prevalence of staphylococcal species, virulence and antibiotic resistance genes in bovine mastitis from China are limited. In this study, 104 out of 209 subclinical mastitis milk samples from a single Chinese dairy herd were cultured-positive for staphylococci (49.8%), which were further identified as coagulase-positive staphylococci (CPS) or coagulase-negative staphylococci (CNS). According to the partial tuf and/or 16S rRNA gene sequence, the 28 CPS isolates were confirmed to be Staphylococcus aureus (26.9%), and 76 CNS isolates were assigned to 13 different species (73.1%) with Staphylococcus arlettae, Staphylococcus sciuri, Staphylococcus xylosus and Staphylococcus chromogenes as the dominant species. In the 28 S. aureus isolates, the most prevalent general virulence genes were coa, Ig and eno (100%), followed by hla (96.4%), hlb (92.9%), fib (92.9%), clfA (89.3%), clfB (85.7%) and nuc (85.7%). Both exotoxin and biofilm-associated genes were significantly less prevalent than the previously reported. Although 19 different virulence gene patterns were found, only one was dominant (32.1%). The prevalence of blaZ (82.1%) or mecA gene (35.7%) was much higher than the previously reported. In the 76 CNS isolates, the virulence genes were significantly less prevalent than that in the S. aureus isolates. Among the 4 main CNS species, S. chromogenes (n = 12) was the only species with high percentage (75%) of blaZ gene, while S. sciuri (n = 12) was the only species with the high percentage (66.7%) of mecA gene. The most of antibiotic resistance genes were present as multi-resistance genes, and the antibiotic resistances were attributed by different resistance genes between resistant S. aureus and CNS isolates. These data suggest that the prevalence of staphylococcal species, virulence and antibiotic resistance in the mastitis milk from the Chinese

  1. Influence of Klebsiella pneumoniae CRP protein on bacterial adhesion and virulence in vitro%肺炎克雷伯菌转录调控子CRP对菌株粘附能力及细胞活性的影响

    Institute of Scientific and Technical Information of China (English)

    谭斌; 白群华; 罗美; 杨世亚; 薛健; 周锡鹏; 李迎丽; 邱景富

    2014-01-01

    Objective To analyze the adhesion and cell virulence of Klebsiella pneumonia wild type (WT) strain,complemented strain c-Δcrp (cAMP receptor protein) and mutant strain Δcrp,in order to investigate crp gene on the adhesion and cell toxicity of Klebsiella pneumonia.Methods After infection of A549 cells by Klebsiella pneumonia WT strain,c-Δcrp strain and Δcrp strain,the cells were lysed and the bacteria were quantified by plating appropriate dilutions on Luria-Bertani agar plates.LDH release was detected to estimate cell activity.Infection time and MOI were optimized.Results The adhesion ability of Klebsiella pneumonia WT (logCFU =5.145) and c-Δcrp strain (logCFU =4.915) was higher than that of Δcrp strain (logCFU =4.122) (P =0.004).The optimal conditions to determinate the LDH release included infected cells incubation for 8 h at 37 ℃,the developing time for 10 min in dark,and 1:10 dilution of the supernatant for test.The virulence of WT strain (70.69%) was significantly higher than that of Δcrp strain (19.54%) (P=0.001).Conclusion Knocking-out of crp gene causes obvious decrease of cellular toxicity and adhesion,comparing with the WT strain and c-Δcrp strain.Klebsiella pneumonia CRP protein positively regulates bacterial virulence and adhesion.%目的 分析肺炎克雷伯菌临床分离株WT(wild type)、回补株(c-Δcrp)和突变株(Δcrp)对人肺癌上皮细胞A549细胞的粘附能力及细胞活性的影响.方法 肺炎克雷伯菌WT株、c-Δcrp株和Δcrp株感染人肺癌上皮细胞A549,经裂解液裂解后平板计数计算粘附的菌量.LDH释放法检测细菌对细胞的毒性,优化感染时间和感染指数.结果 WT株及c-Δcrp株粘附的菌量分别为logCFU=5.145和logCFU=4.915,均高于Δcrp株(logCFU=4.122),差异有统计学意义(F=8.366,P=0.004).以MOI=1 000(细菌∶细胞=1000)的菌量感染靶细胞,37℃孵育8h,加底物液避光显色10 min,离心所得上清稀释10倍进行测定为最佳反应条件.WT

  2. Characterisation of Escherichia coli O157 isolates from Danish cattle and human patients by genotyping and presence and variants of virulence genes

    DEFF Research Database (Denmark)

    Nielsen, Eva Møller; Scheutz, Flemming

    2002-01-01

    Escherichia coli O157 isolates obtained from 17 Danish cattle herds and from a national surveillance programme of cattle at slaughter were genotyped by pulsed-field gel electrophoresis (PFGE) and characterised with respect to presence of and variation in virulence factors. The characteristics of...... the cattle strains were compared to human clinical isolates from the same time period. All verocytotoxin (VT)-producing E. coli O157 (VTEC O157) from cattle possessed all typical VTEC O157:H7 virulence factors and had either the VT2c-variant alone or together with VT1. Among human isolates the...... possessed the eae gene and all other genotypic and phenotypic traits typical for E. coli O157:H7. On the basis of the virulence characteristics, it is concluded that the VTEC O157 strains isolated from Danish cattle are potential human pathogens. However, the observed differences between cattle and human...

  3. Directed evolution induces tributyrin hydrolysis in a virulence factor of Xylella fastidiosa using a duplicated gene as a template.

    Science.gov (United States)

    Gouran, Hossein; Chakraborty, Sandeep; Rao, Basuthkar J; Asgeirsson, Bjarni; Dandekar, Abhaya

    2014-01-01

    Duplication of genes is one of the preferred ways for natural selection to add advantageous functionality to the genome without having to reinvent the wheel with respect to catalytic efficiency and protein stability. The duplicated secretory virulence factors of Xylella fastidiosa (LesA, LesB and LesC), implicated in Pierce's disease of grape and citrus variegated chlorosis of citrus species, epitomizes the positive selection pressures exerted on advantageous genes in such pathogens. A deeper insight into the evolution of these lipases/esterases is essential to develop resistance mechanisms in transgenic plants. Directed evolution, an attempt to accelerate the evolutionary steps in the laboratory, is inherently simple when targeted for loss of function. A bigger challenge is to specify mutations that endow a new function, such as a lost functionality in a duplicated gene. Previously, we have proposed a method for enumerating candidates for mutations intended to transfer the functionality of one protein into another related protein based on the spatial and electrostatic properties of the active site residues (DECAAF). In the current work, we present in vivo validation of DECAAF by inducing tributyrin hydrolysis in LesB based on the active site similarity to LesA. The structures of these proteins have been modeled using RaptorX based on the closely related LipA protein from Xanthomonas oryzae. These mutations replicate the spatial and electrostatic conformation of LesA in the modeled structure of the mutant LesB as well, providing in silico validation before proceeding to the laborious in vivo work. Such focused mutations allows one to dissect the relevance of the duplicated genes in finer detail as compared to gene knockouts, since they do not interfere with other moonlighting functions, protein expression levels or protein-protein interaction. PMID:25717364

  4. Detection of genes encoding multidrug resistance and biofilm virulence factor in uterine pathogenic bacteria in postpartum dairy cows.

    Science.gov (United States)

    Kasimanickam, V R; Owen, K; Kasimanickam, R K

    2016-01-15

    Reckless use of antibiotics and/or development of biofilm are the rationale for the development of multidrug resistance (MDR) of pathogenic bacteria. The objective of the present study was to detect MDR genes in Trueperella pyogenes and to detect biofilm virulence factor (VF) genes in Escherichia coli isolated from the uterus of postpartum dairy cows. Uterine secretions from different parity postpartum Holstein cows (n = 40) were collected using cytobrush technique after a sterile procedure from cows with varying degree of uterine inflammatory conditions. The cytobrush was stored in a specimen collector, placed in a cooler with ice, and transported to the laboratory within 2 hours. The pathogens were isolated and were identified initially by their colony morphology and biochemical characteristics. To further identify and classify the single species, and to determine the presence of MDR and VF genes, the genes fragments were amplified using the respective primers by either singleplex or multiplex polymerase chain reaction protocol, and amplicons were detected by electrophoresis method. T pyogenes was isolated in 17 of 40 (42.5%) cows in the study population as recognized by the 16S rRNA gene. Of the positive T pyogenes samples, 8 of 17 (42.1%) were positive for integron type 1 (intI I), and none were positive for integron type 2 (intI II). Of those 8 positive for intI I, six of eight (66.7%) were positive for amplicons aadA5 and aadA24-ORF1 at 1048 and 1608 bp, respectively, associated with specific drug resistance. Presence of addA5 indicated resistance to sulfadiazine, bacitracin, florfenicol, and ceftiofur. Presence of addA24-ORF1 indicated resistant to sulfadiazine, bacitracin, penicillin, clindamycin, and erythromycin. E coli was isolated in 18 of 40 (45.0%) cows in the study population. The genes for VF, Agn43a, and Agn43 b, associated with biofilm production, were found in 6 of 18 (33.3%) of the positive isolates. Both T pyogenes MDR gene and E coli

  5. Bioinformatic analysis reveals high diversity of bacterial genes for laccase-like enzymes.

    Directory of Open Access Journals (Sweden)

    Luka Ausec

    Full Text Available Fungal laccases have been used in various fields ranging from processes in wood and paper industries to environmental applications. Although a few bacterial laccases have been characterized in recent years, prokaryotes have largely been neglected as a source of novel enzymes, in part due to the lack of knowledge about the diversity and distribution of laccases within Bacteria. In this work genes for laccase-like enzymes were searched for in over 2,200 complete and draft bacterial genomes and four metagenomic datasets, using the custom profile Hidden Markov Models for two- and three-domain laccases. More than 1,200 putative genes for laccase-like enzymes were retrieved from chromosomes and plasmids of diverse bacteria. In 76% of the genes, signal peptides were predicted, indicating that these bacterial laccases may be exported from the cytoplasm, which contrasts with the current belief. Moreover, several examples of putatively horizontally transferred bacterial laccase genes were described. Many metagenomic sequences encoding fragments of laccase-like enzymes could not be phylogenetically assigned, indicating considerable novelty. Laccase-like genes were also found in anaerobic bacteria, autotrophs and alkaliphiles, thus opening new hypotheses regarding their ecological functions. Bacteria identified as carrying laccase genes represent potential sources for future biotechnological applications.

  6. Genes as early responders regulate quorum-sensing and control bacterial cooperation in Pseudomonas aeruginosa.

    Directory of Open Access Journals (Sweden)

    Kelei Zhao

    Full Text Available Quorum-sensing (QS allows bacterial communication to coordinate the production of extracellular products essential for population fitness at higher cell densities. It has been generally accepted that a significant time duration is required to reach appropriate cell density to activate the relevant quiescent genes encoding these costly but beneficial public goods. Which regulatory genes are involved and how these genes control bacterial communication at the early phases are largely un-explored. By determining time-dependent expression of QS-related genes of the opportunistic pathogen Pseudomonas aerugionsa, we show that the induction of social cooperation could be critically influenced by environmental factors to optimize the density of population. In particular, small regulatory RNAs (RsmY and RsmZ serving as early responders, can promote the expression of dependent genes (e.g. lasR to boost the synthesis of intracellular enzymes and coordinate instant cooperative behavior in bacterial cells. These early responders, acting as a rheostat to finely modulate bacterial cooperation, which may be quickly activated under environment threats, but peter off when critical QS dependent genes are fully functional for cooperation. Our findings suggest that RsmY and RsmZ critically control the timing and levels of public goods production, which may have implications in sociomicrobiology and infection control.

  7. Bioinformatic Analysis Reveals High Diversity of Bacterial Genes for Laccase-Like Enzymes

    Science.gov (United States)

    Ausec, Luka; Zakrzewski, Martha; Goesmann, Alexander; Schlüter, Andreas; Mandic-Mulec, Ines

    2011-01-01

    Fungal laccases have been used in various fields ranging from processes in wood and paper industries to environmental applications. Although a few bacterial laccases have been characterized in recent years, prokaryotes have largely been neglected as a source of novel enzymes, in part due to the lack of knowledge about the diversity and distribution of laccases within Bacteria. In this work genes for laccase-like enzymes were searched for in over 2,200 complete and draft bacterial genomes and four metagenomic datasets, using the custom profile Hidden Markov Models for two- and three- domain laccases. More than 1,200 putative genes for laccase-like enzymes were retrieved from chromosomes and plasmids of diverse bacteria. In 76% of the genes, signal peptides were predicted, indicating that these bacterial laccases may be exported from the cytoplasm, which contrasts with the current belief. Moreover, several examples of putatively horizontally transferred bacterial laccase genes were described. Many metagenomic sequences encoding fragments of laccase-like enzymes could not be phylogenetically assigned, indicating considerable novelty. Laccase-like genes were also found in anaerobic bacteria, autotrophs and alkaliphiles, thus opening new hypotheses regarding their ecological functions. Bacteria identified as carrying laccase genes represent potential sources for future biotechnological applications. PMID:22022440

  8. Role of pneumococcal virulence genes in the etiology of respiratory tract infection and biofilm formation

    OpenAIRE

    Kurola, P. (Paula)

    2011-01-01

    Abstract Streptococcus pneumoniae, pneumococcus, is a common cause of respiratory tract infections and also a common inhabitant of the upper respiratory tract of healthy people. At present, 93 different polysaccharide types have been identified and in addition to them, unencapsulated pneumococci are found especially in healthy carriers. Pneumococci are usually identified by using a bacterial culture combined with biochemical or immunochemical tests. Recently, new DNA-based methods, such a...

  9. Genetic Variation of the VP1 Gene of the Virulent Duck Hepatitis A Virus Type 1 (DHAV-1) Isolates in Shandong Province of China

    Institute of Scientific and Technical Information of China (English)

    Jiming Gao; Junhao Chen; Xingkui Si; Zhijing Xie; Yanli Zhu; Xingxiao Zhang; Shujing Wang; Shijin Jiang

    2012-01-01

    To investigate the relationship of the variation of virulence and the external capsid proteins of the pandemic duck hepatitis A virus type 1(DHAV-1) isolates,the virulence,cross neutralization assays and the complete sequence of the virion protein 1(VP1) gene of nine virulent DHAV-1 strains,which were isolated from infected ducklings with clinical symptoms in Shandong province of China in 2007-2008,were tested.The fifth generation duck embryo allantoic liquids of the 9 isolates were tested on 12-day-old duck embryos and on 7-day-old ducklings for the median embryonal lethal doses(ELD50s) and the median lethal doses(LD50s),respectively.The results showed that the ELD5s of embryonic duck eggs of the 9 DHAV-1 isolates were between 1.9 × 106/mL to 1.44 × 107/mL,while the LD50s were 2.39 × 105/mL to 6.15 × 106/mL.Cross-neutralization tests revealed that the 9 DHAV-1 isolates were completely neutralized by the standard serum and the hyperimmune sera against the 9 DHAV-1 isolates,respectively.Compared with other virulent,moderate virulent,attenuated vaccine and mild strains,the VP1 genes of the 9 strains shared 89.8%-99.7% similarity at the nucleotide level and 92.4%-99.6% at amino acid level with other DHAV-1 strains.There were three hypervariable regions at the C-terminus(as 158-160,180-193 and 205-219) and other variable points in VPI protein,but which didn't cause virulence of DHAV-1 change.

  10. More than 9,000,000 Unique Genes in Human Gut Bacterial Community: Estimating Gene Numbers Inside a Human Body

    OpenAIRE

    Yang, Xing; Xie, Lu; Li, Yixue; Wei, Chaochun

    2009-01-01

    Background Estimating the number of genes in human genome has been long an important problem in computational biology. With the new conception of considering human as a super-organism, it is also interesting to estimate the number of genes in this human super-organism. Principal Findings We presented our estimation of gene numbers in the human gut bacterial community, the largest microbial community inside the human super-organism. We got 552,700 unique genes from 202 complete human gut bacte...

  11. cis-Acting elements that control expression of the master virulence regulatory gene atxA in Bacillus anthracis.

    Science.gov (United States)

    Dale, Jennifer L; Raynor, Malik J; Dwivedi, Prabhat; Koehler, Theresa M

    2012-08-01

    Transcription of the Bacillus anthracis structural genes for the anthrax toxin proteins and biosynthetic operon for capsule is positively regulated by AtxA, a transcription regulator with unique properties. Consistent with the role of atxA in virulence factor expression, a B. anthracis atxA-null mutant is avirulent in a murine model for anthrax. In culture, multiple signals impact atxA transcript levels, and the timing and steady-state level of atxA expression are critical for optimal toxin and capsule synthesis. Despite the apparent complex control of atxA transcription, only one trans-acting protein, the transition state regulator AbrB, has been demonstrated to interact directly with the atxA promoter. Here we employ 5' and 3' deletion analysis and site-directed mutagenesis of the atxA control region to demonstrate that atxA transcription from the major start site P1 is dependent upon a consensus sequence for the housekeeping sigma factor SigA and an A+T-rich upstream element for RNA polymerase. We also show that an additional trans-acting protein(s) binds specifically to atxA promoter sequences located between -13 and +36 relative to P1 and negatively impacts transcription. Deletion of this region increases promoter activity up to 15-fold. Site-directed mutagenesis of a 9-bp palindromic sequence within the region prevents binding of the trans-acting protein(s), increasing promoter activity 7-fold and resulting in a corresponding increase in AtxA and anthrax toxin production. Notably, an atxA promoter mutant that produced elevated levels of AtxA and toxin proteins during culture was unaffected for virulence in a murine model for anthrax. PMID:22636778

  12. AlgU controls expression of virulence genes in Pseudomonas syringae pv. tomato DC3000

    Science.gov (United States)

    Plant pathogenic bacteria are able to integrate information about their environment and adjust gene expression to provide adaptive functions. AlgU, an ECF sigma factor encoded by Pseudomonas syringae, controls expression of genes for alginate biosynthesis and is active while the bacteria are associa...

  13. Some virulence genes of Escherichia coli isolated from cloacal swabs of healthy Alagoas Curassows (Pauxi mitu in Brazil

    Directory of Open Access Journals (Sweden)

    André A.B. Saidenberg

    2013-04-01

    Full Text Available Birds of the Cracidae family (curassows, guans, and chachalacas are endemic of the Neotropics and 50 species are currently classified. Brazil has 22 species, seven of which are considered threatened. The Alagoas Curassow (Pauxi mitu species is considered extinct in the wild; but about 120 birds are alive in captivity. Conservation of this species depends entirely on correct management. Health reports of both wildlife and captive curassows are rare. In this study the presence of Escherichia coli was evaluated in 23 healthy Alagoas Curassows from two private breeding centres. E. coli was isolated from cloacal swabs, and the presence of genes encoding cytotoxic necrotising factor 1 (cnf1, alpha-haemolysin (hly, aerobactin (iuc, serum resistance (iss and the following adhesions: S fimbriae (sfa, pili associated with pyelonephritis (pap and temperature-sensitive haemagglutinin (tsh were investigated. E. coli was isolated from 78.3% (18/23 of the birds, and the percentage of curassows colonized by E. coli was similar between the two facilities. From the 22 E. coli isolates, 15 (68.2% were positive for at least one virulence factor by PCR, and the most frequently found gene was iss (50%. No curassows had clinical signs of disease. Nevertheless, the presence of some E. coli strains may be a concern to the wildlife in captivity. Additional health surveillance studies are essential to guarantee successful conservation programmes for threatened cracids in Brazil.

  14. 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. PMID:26910039

  15. Relationships between antimicrobial resistance, distribution of virulence factor genes and the origin of Trueperella pyogenes isolated from domestic animals and European bison (Bison bonasus).

    Science.gov (United States)

    Rzewuska, Magdalena; Czopowicz, Michał; Gawryś, Marta; Markowska-Daniel, Iwona; Bielecki, Wojciech

    2016-07-01

    Trueperella pyogenes is an opportunistic pathogen causing suppurative infections in livestock and wild animals. Although this bacterium is known for a long time, our knowledge about its pathogenicity is still insufficient. In this study the relationships between antimicrobial resistance profiles, distribution of virulence factor genes and the origin of T. pyogenes isolates were investigated. Isolates (n = 97) from various infections in domestic animals and European bison were studied. Minimal inhibitory concentrations of 12 antimicrobials were determined by a strip diffusion method, and PCR was used for detection of genes encoding seven putative virulence factors. All strains were susceptible to tested beta-lactams, and a statistically significant correlation between the resistance to enrofloxacin, tetracycline, macrolides, clindamycin, and a strain origin was found. The isolates from European bison were more susceptible than those from livestock, however the resistance to tetracycline and fluoroquinolones was observed. The plo and fimA genes were detected in all strains. There was no statistically significant association between the distribution of particular virulence factor genes and the type of infection, but the nanH, nanP and fimG genes were less frequently found in the isolates from European bison. The presence of three genes, nanP, nanH and cbpA, was found to be related to the resistance to tetracycline and ciprofloxacin. In conclusion, the resistance patterns of T. pyogenes were correlated with an isolate origin, but our findings did not allow to indicate which of the putative virulence factors may play a crucial role in the pathogenesis of particular types of T. pyogenes infection. PMID:27154538

  16. An antisense RNA that governs the expression kinetics of a multifunctional virulence gene

    OpenAIRE

    Lee, Eun-Jin; Groisman, Eduardo A.

    2010-01-01

    Genome-wide transcriptome analyses of several bacterial species have recently uncovered a hitherto unappreciated amount of antisense transcription. However, the physiological role, regulation and significance of such antisense transcripts are presently unclear. We now report the identification of a cis-encoded 1.2 kb long antisense RNA – termed AmgR – that is complementary to the mgtC portion of the mgtCBR polycistronic message from Salmonella enterica. The mgtCBR mRNA specifies the MgtC prot...

  17. Comparison on virulence and immunogenicity of two recombinant vaccinia vaccines, Tian Tan and Guang9 strains, expressing the HIV-1 envelope gene.

    Directory of Open Access Journals (Sweden)

    Rong Zhu

    Full Text Available BACKGROUND: The vaccinia virus Guang9 strain (VG9, derived from the vaccinia virus Tian Tan strain (VTT has been found to be less virulent than VTT. METHODOLOGY/PRINCIPAL FINDINGS: To investigate whether VG9 could be a potential replicating virus vector, the TK genes in VG9 and VTT were replaced with the HIV-1 envelope gene via homologous recombination, resulting in the recombinant viruses, VG9-E and VTT-E. The biology, virulence, humoral and cellular immunological responses of VG9-E and VTT-E were evaluated. Our results indicated no obvious difference in range of host cells and diffusion between two recombinant viruses. Neurovirulence for VG9-E in weanling and suckling mice, and skin virulence in rabbits, were lower than that of VTT-E. The humoral immune responses, including binding antibody and neutralizing antibody responses, induced by VG9-E were not significantly different from those for VTT-E whilst IFN-γ response which represented cellular immune response induced by VG9-E was significantly higher than that did by VTT-E. CONCLUSIONS/SIGNIFICANCE: Our results indicated that VG9-E was less virulent, yet induced higher cellular immune response than VTT-E. Therefore, it could be an ideal replicating vaccinia vector for HIV vaccine research and development.

  18. The minimal gene set member msrA, encoding peptide methionine sulfoxide reductase, is a virulence determinant of the plant pathogen Erwinia chrysanthemi.

    Science.gov (United States)

    Hassouni, M E; Chambost, J P; Expert, D; Van Gijsegem, F; Barras, F

    1999-02-01

    Peptide methionine sulfoxide reductase (MsrA), which repairs oxidized proteins, is present in most living organisms, and the cognate structural gene belongs to the so-called minimum gene set [Mushegian, A. R. & Koonin, E. V., (1996) Proc. Natl. Acad. Sci. USA 93, 10268-10273]. In this work, we report that MsrA is required for full virulence of the plant pathogen Erwinia chrysanthemi. The following differences were observed between the wild-type and a MsrA- mutant: (i) the MsrA- mutant was more sensitive to oxidative stress; (ii) the MsrA- mutant was less motile on solid surface; (iii) the MsrA- mutant exhibited reduced virulence on chicory leaves; and (iv) no systemic invasion was observed when the MsrA- mutant was inoculated into whole Saintpaulia ionantha plants. These results suggest that plants respond to virulent pathogens by producing active oxygen species, and that enzymes repairing oxidative damage allow virulent pathogens to survive the host environment, thereby supporting the theory that active oxygen species play a key role in plant defense. PMID:9927663

  19. Survey of culture, goldengate assay, universal biosensor assay, and 16S rRNA Gene sequencing as alternative methods of bacterial pathogen detection.

    Science.gov (United States)

    Lindsay, Brianna; Pop, Mihai; Antonio, Martin; Walker, Alan W; Mai, Volker; Ahmed, Dilruba; Oundo, Joseph; Tamboura, Boubou; Panchalingam, Sandra; Levine, Myron M; Kotloff, Karen; Li, Shan; Magder, Laurence S; Paulson, Joseph N; Liu, Bo; Ikumapayi, Usman; Ebruke, Chinelo; Dione, Michel; Adeyemi, Mitchell; Rance, Richard; Stares, Mark D; Ukhanova, Maria; Barnes, Bret; Lewis, Ian; Ahmed, Firoz; Alam, Meer Taifur; Amin, Ruhul; Siddiqui, Sabbir; Ochieng, John B; Ouma, Emmanuel; Juma, Jane; Mailu, Eunice; Omore, Richard; O'Reilly, Ciara E; Hannis, James; Manalili, Sheri; Deleon, Jonna; Yasuda, Irene; Blyn, Lawrence; Ranken, Raymond; Li, Feng; Housley, Roberta; Ecker, David J; Hossain, M Anowar; Breiman, Robert F; Morris, J Glenn; McDaniel, Timothy K; Parkhill, Julian; Saha, Debasish; Sampath, Rangarajan; Stine, O Colin; Nataro, James P

    2013-10-01

    Cultivation-based assays combined with PCR or enzyme-linked immunosorbent assay (ELISA)-based methods for finding virulence factors are standard methods for detecting bacterial pathogens in stools; however, with emerging molecular technologies, new methods have become available. The aim of this study was to compare four distinct detection technologies for the identification of pathogens in stools from children under 5 years of age in The Gambia, Mali, Kenya, and Bangladesh. The children were identified, using currently accepted clinical protocols, as either controls or cases with moderate to severe diarrhea. A total of 3,610 stool samples were tested by established clinical culture techniques: 3,179 DNA samples by the Universal Biosensor assay (Ibis Biosciences, Inc.), 1,466 DNA samples by the GoldenGate assay (Illumina), and 1,006 DNA samples by sequencing of 16S rRNA genes. Each method detected different proportions of samples testing positive for each of seven enteric pathogens, enteroaggregative Escherichia coli (EAEC), enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), Shigella spp., Campylobacter jejuni, Salmonella enterica, and Aeromonas spp. The comparisons among detection methods included the frequency of positive stool samples and kappa values for making pairwise comparisons. Overall, the standard culture methods detected Shigella spp., EPEC, ETEC, and EAEC in smaller proportions of the samples than either of the methods based on detection of the virulence genes from DNA in whole stools. The GoldenGate method revealed the greatest agreement with the other methods. The agreement among methods was higher in cases than in controls. The new molecular technologies have a high potential for highly sensitive identification of bacterial diarrheal pathogens. PMID:23884998

  20. Towards allele mining of bacterial wilt disease resistance gene in tomato

    International Nuclear Information System (INIS)

    Tomato (Lycopersicon esculentum Mill.) is the most important vegetable commodity of the Philippines. Bacterial wilt caused by Ralstonia solanacearum is one serious constraint in tomato production particularly during off-season planting. A major locus derived from H7996 that confers resistance to bacterial wilt has been mapped in the tomato genome. To validate the biological function of the resistance locus and generate multiple allele -mimics-, targeted mutation was induced in tomato using gamma ray and ethyl methane sulfonate (EMS) mutagens. Suitable mutagen treatment was established by evaluating a wide range of mutagen doses/concentrations for a) percent seed germination, b) reduction in plant height, and c) loss of resistance. Six hundred Gy and 1.0% EMS were identified to generate large M1 families of H7996. From 10,000 initial seeds treated with either gamma ray or EMS, a total of 3,663 M1 plants were generated. M2 seeds were harvested from all surviving M1 plants. Several DNA markers have been resourced and are being developed specific to the bacterial wilt resistant gene. In the large M2 population, of H7996, both the phenotypic manifestation of bacterial wilt susceptibility and nucleotide changes in the resistance locus will be evaluated. Large M3 families for the different allele series of the bacterial wilt resistance gene will be established for future high throughput TILLING (Targeting Induced Local Lesions in Genomes) analysis in the gene region

  1. Transcriptome of Proteus mirabilis in the murine urinary tract: virulence and nitrogen assimilation gene expression.

    Science.gov (United States)

    Pearson, Melanie M; Yep, Alejandra; Smith, Sara N; Mobley, Harry L T

    2011-07-01

    The enteric bacterium Proteus mirabilis is a common cause of complicated urinary tract infections. In this study, microarrays were used to analyze P. mirabilis gene expression in vivo from experimentally infected mice. Urine was collected at 1, 3, and 7 days postinfection, and RNA was isolated from bacteria in the urine for transcriptional analysis. Across nine microarrays, 471 genes were upregulated and 82 were downregulated in vivo compared to in vitro broth culture. Genes upregulated in vivo encoded mannose-resistant Proteus-like (MR/P) fimbriae, urease, iron uptake systems, amino acid and peptide transporters, pyruvate metabolism enzymes, and a portion of the tricarboxylic acid (TCA) cycle enzymes. Flagella were downregulated. Ammonia assimilation gene glnA (glutamine synthetase) was repressed in vivo, while gdhA (glutamate dehydrogenase) was upregulated in vivo. Contrary to our expectations, ammonia availability due to urease activity in P. mirabilis did not drive this gene expression. A gdhA mutant was growth deficient in minimal medium with citrate as the sole carbon source, and loss of gdhA resulted in a significant fitness defect in the mouse model of urinary tract infection. Unlike Escherichia coli, which represses gdhA and upregulates glnA in vivo and cannot utilize citrate, the data suggest that P. mirabilis uses glutamate dehydrogenase to monitor carbon-nitrogen balance, and this ability contributes to the pathogenic potential of P. mirabilis in the urinary tract. PMID:21505083

  2. A Zinc-Finger-Family Transcription Factor, AbVf19, Is Required for the Induction of a Gene Subset Important for Virulence in Alternaria brassicicola

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Akhil [Univ. of Hawaii, Manoa, HI (United States); Ohm, Robin A. [USDOE Joint Genome Inst., Walnut Creek, CA (United States); Oxiles, Lindsay [Univ. of Hawaii, Manoa, HI (United States); Brooks, Fred [Univ. of Hawaii, Manoa, HI (United States); Lawrence, Christopher B. [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Grigoriev, Igor V. [USDOE Joint Genome Inst., Walnut Creek, CA (United States); Cho, Yangrae [Univ. of Hawaii, Manoa, HI (United States)

    2011-10-26

    Alternaria brassicicola is a successful saprophyte and necrotrophic plant pathogen with a broad host range within the family Brassicaceae. It produces secondary metabolites that marginally affect virulence. Cell wall degrading enzymes (CDWE) have been considered important for pathogenesis but none of them individually have been identified as significant virulence factors in A. brassicicola. In this study, knockout mutants of a gene, AbVf19, were created and produced considerably smaller lesions than the wild type on inoculated host plants. The presence of tandem zinc-finger domains in the predicted amino acid sequence and nuclear localization of AbVf19- reporter protein suggested that it was a transcription factor. Gene expression comparisons using RNA-seq identified 74 genes being downregulated in the mutant during a late stage of infection. Among the 74 downregulated genes, 28 were putative CWDE genes. These were hydrolytic enzyme genes that composed a small fraction of genes within each family of cellulases, pectinases, cutinases, and proteinases. The mutants grew slower than the wild type on an axenic medium with pectin as a major carbon source. This study demonstrated the existence and the importance of a transcription factor that regulates a suite of genes that are important for decomposing and utilizing plant material during the late stage of plant infection.

  3. Distribution of nine virulence-associated genes in Campylobacter jejuni and C. coli isolated from broiler feces in Shiraz, Southern Iran.

    Science.gov (United States)

    Khoshbakht, Rahem; Tabatabaei, Mohammad; Hosseinzadeh, Saeid; Shekarforoush, Seied Shahram; Aski, Hesamaddin Shirzad

    2013-09-01

    To investigate the prevalence of nine virulence and toxin genes of Campylobacter, a total of 90 Campylobacter strains including 48 C. jejuni and 42 C. coli were recovered from chicken feces by cultivation methods. The isolates were identified on the basis of polymerase chain reaction (PCR) detection of 16SrRNA and multiplex PCR for determining two species. For confirmed strains, PCR was carried out for the presence of virulence genes using specific primers. Data were analyzed by SPSS software, version 12.0.1. The cadF gene and three genes associated with cytolethal distending toxin were present in 100% of isolates. Plasmid virB11 gene was not found in any of the Campylobacter isolates, and the prevalence of pldA, wlaN, iamA, and cgtB genes were 92.22%, 82.22%, 81.11%, and 22.22%, respectively. The findings revealed that the distribution of the majority of these genes were not dissimilar among Campylobacter species. The results emphasized that many of the pathogenic C. jejuni and C. coli may have these genes, and the Campylobacter strains with poultry origin have pathogenic potential properties for humans. PMID:23789768

  4. Novel terpenes generated by heterologous expression of bacterial terpene synthase genes in an engineered Streptomyces host

    OpenAIRE

    YAMADA, YUUKI; Arima, Shiho; Nagamitsu, Tohru; Johmoto, Kohei; Uekusa, Hidehiro; Eguchi, Tadashi; Shin’ya, Kazuo; Cane, David E.; Ikeda, Haruo

    2015-01-01

    Mining of bacterial genome data has revealed numerous presumptive terpene synthases. Heterologous expression of several putative terpene synthase genes in an engineered Streptomyces host has revealed 13 newly discovered terpenes whose GC-MS and NMR data did not match any known compounds in the spectroscopic databases. Each of the genes encoding the corresponding terpene synthases were silent in their parent microorganisms. Heterologous expression and detailed NMR spectroscopic analysis allowe...

  5. A novel subtyping assay for detection of Clostridium difficile virulence genes.

    Science.gov (United States)

    Angione, Stephanie L; Sarma, Aartik A; Novikov, Aleksey; Seward, Leah; Fieber, Jennifer H; Mermel, Leonard A; Tripathi, Anubhav

    2014-03-01

    This proof-of-concept study demonstrates the application of a novel nucleic acid detection platform to detect Clostridium difficile in subjects presenting with acute diarrheal symptoms. This method amplifies three genes associated with C. difficile infection, including genes and deletions (cdtB and tcdC) associated with hypervirulence attributed to the NAP1/027/BI strain. Amplification of DNA from the tcdB, tcdC, and cdtB genes was performed using a droplet-based sandwich platform with quantitative real-time PCR in microliter droplets to detect and identify the amplified fragments of DNA. The device and identification system are simple in design and can be integrated as a point-of-care test to help rapidly detect and identify C. difficile strains that pose significant health threats in hospitals and other health-care communities. PMID:24434086

  6. Cotransfer of Antibiotic Resistance Genes and a hylEfm-Containing Virulence Plasmid in Enterococcus faecium▿

    OpenAIRE

    Arias, Cesar A.; Panesso, Diana; Singh, Kavindra V.; Rice, Louis B.; Murray, Barbara E.

    2009-01-01

    The hylEfm gene (encoding a putative hyaluronidase) has been found almost exclusively in Enterococcus faecium clinical isolates, and recently, it was shown to be on a plasmid which increased the ability of E. faecium strains to colonize the gastrointestinal tract. In this work, the results of mating experiments between hylEfm-containing strains of E. faecium belonging to clonal cluster 17 and isolated in the United States and Colombia indicated that the hylEfm gene of these strains is also ca...

  7. Host response to respiratory bacterial pathogens as identified by integrated analysis of human gene expression data.

    Directory of Open Access Journals (Sweden)

    Steven B Smith

    Full Text Available Respiratory bacterial pathogens are one of the leading causes of infectious death in the world and a major health concern complicated by the rise of multi-antibiotic resistant strains. Therapeutics that modulate host genes essential for pathogen infectivity could potentially avoid multi-drug resistance and provide a wider scope of treatment options. Here, we perform an integrative analysis of published human gene expression data generated under challenges from the gram-negative and Gram-positive bacteria pathogens, Pseudomonas aeruginosa and Streptococcus pneumoniae, respectively. We applied a previously described differential gene and pathway enrichment analysis pipeline to publicly available host mRNA GEO datasets resulting from exposure to bacterial infection. We found 72 canonical human pathways common between four GEO datasets, representing P. aeruginosa and S. pneumoniae. Although the majority of these pathways are known to be involved with immune response, we found several interesting new interactions such as the SUMO1 pathway that might have a role in bacterial infections. Furthermore, 36 host-bacterial pathways were also shared with our previous results for respiratory virus host gene expression. Based on our pathway analysis we propose several drug-repurposing opportunities supported by the literature.

  8. Genetic diversity of bacterial communities and gene transfer agents in northern South China Sea.

    Directory of Open Access Journals (Sweden)

    Fu-Lin Sun

    Full Text Available Pyrosequencing of the 16S ribosomal RNA gene (rDNA amplicons was performed to investigate the unique distribution of bacterial communities in northern South China Sea (nSCS and evaluate community structure and spatial differences of bacterial diversity. Cyanobacteria, Proteobacteria, Actinobacteria, and Bacteroidetes constitute the majority of bacteria. The taxonomic description of bacterial communities revealed that more Chroococcales, SAR11 clade, Acidimicrobiales, Rhodobacterales, and Flavobacteriales are present in the nSCS waters than other bacterial groups. Rhodobacterales were less abundant in tropical water (nSCS than in temperate and cold waters. Furthermore, the diversity of Rhodobacterales based on the gene transfer agent (GTA major capsid gene (g5 was investigated. Four g5 gene clone libraries were constructed from samples representing different regions and yielded diverse sequences. Fourteen g5 clusters could be identified among 197 nSCS clones. These clusters were also related to known g5 sequences derived from genome-sequenced Rhodobacterales. The composition of g5 sequences in surface water varied with the g5 sequences in the sampling sites; this result indicated that the Rhodobacterales population could be highly diverse in nSCS. Phylogenetic tree analysis result indicated distinguishable diversity patterns among tropical (nSCS, temperate, and cold waters, thereby supporting the niche adaptation of specific Rhodobacterales members in unique environments.

  9. Cereulide synthetase gene cluster from emetic Bacillus cereus: Structure and location on a mega virulence plasmid related to Bacillus anthracis toxin plasmid pXO1

    Directory of Open Access Journals (Sweden)

    Wagner Martin

    2006-03-01

    Full Text Available Abstract Background Cereulide, a depsipeptide structurally related to valinomycin, is responsible for the emetic type of gastrointestinal disease caused by Bacillus cereus. Recently, it has been shown that this toxin is produced by a nonribosomal peptide synthetase (NRPS, but its exact genetic organization and biochemical synthesis is unknown. Results The complete sequence of the cereulide synthetase (ces gene cluster, which encodes the enzymatic machinery required for the biosynthesis of cereulide, was dissected. The 24 kb ces gene cluster comprises 7 CDSs and includes, besides the typical NRPS genes like a phosphopantetheinyl transferase and two CDSs encoding enzyme modules for the activation and incorporation of monomers in the growing peptide chain, a CDS encoding a putative hydrolase in the upstream region and an ABC transporter in the downstream part. The enzyme modules responsible for incorporation of the hydroxyl acids showed an unusual structure while the modules responsible for the activation of the amino acids Ala and Val showed the typical domain organization of NRPS. The ces gene locus is flanked by genetic regions with high homology to virulence plasmids of B. cereus, Bacillus thuringiensis and Bacillus anthracis. PFGE and Southern hybridization showed that the ces genes are restricted to emetic B. cereus and indeed located on a 208 kb megaplasmid, which has high similarities to pXO1-like plasmids. Conclusion The ces gene cluster that is located on a pXO1-like virulence plasmid represents, beside the insecticidal and the anthrax toxins, a third type of B. cereus group toxins encoded on megaplasmids. The ces genes are restricted to emetic toxin producers, but pXO1-like plasmids are also present in emetic-like strains. These data might indicate the presence of an ancient plasmid in B. cereus which has acquired different virulence genes over time. Due to the unusual structure of the hydroxyl acid incorporating enzyme modules of Ces

  10. Genomic Insights into a New Citrobacter koseri Strain Revealed Gene Exchanges with the Virulence-Associated Yersinia pestis pPCP1 Plasmid.

    Science.gov (United States)

    Armougom, Fabrice; Bitam, Idir; Croce, Olivier; Merhej, Vicky; Barassi, Lina; Nguyen, Ti-Thien; La Scola, Bernard; Raoult, Didier

    2016-01-01

    The history of infectious diseases raised the plague as one of the most devastating for human beings. Far too often considered an ancient disease, the frequent resurgence of the plague has led to consider it as a reemerging disease in Madagascar, Algeria, Libya, and Congo. The genetic factors associated with the pathogenicity of Yersinia pestis, the causative agent of the plague, involve the acquisition of the pPCP1 plasmid that promotes host invasion through the expression of the virulence factor Pla. The surveillance of plague foci after the 2003 outbreak in Algeria resulted in a positive detection of the specific pla gene of Y. pestis in rodents. However, the phenotypic characterization of the isolate identified a Citrobacter koseri. The comparative genomics of our sequenced C. koseri URMITE genome revealed a mosaic gene structure resulting from the lifestyle of our isolate and provided evidence for gene exchanges with different enteric bacteria. The most striking was the acquisition of a continuous 2 kb genomic fragment containing the virulence factor Pla of the Y. pestis pPCP1 plasmid; however, the subcutaneous injection of the CKU strain in mice did not produce any pathogenic effect. Our findings demonstrate that fast molecular detection of plague using solely the pla gene is unsuitable and should rather require Y. pestis gene marker combinations. We also suggest that the evolutionary force that might govern the expression of pathogenicity can occur through the acquisition of virulence genes but could also require the loss or the inactivation of resident genes such as antivirulence genes. PMID:27014253

  11. The Role of the st313-td Gene in Virulence of Salmonella Typhimurium ST313

    DEFF Research Database (Denmark)

    Herrero-Fresno, Ana; Wallrodt, Inke; Leekitcharoenphon, Pimlapas;

    2014-01-01

    = 82) and 100% of S. Dublin strains (n = 50) analysed. On the contrary, S. Typhimurium isolates of animal and food origin (n = 82) did not carry st313-td. Six human, non-blood isolates of S. Typhimurium from Belarus, China and Nepal harboured the gene and belonged to sequence types ST398 and ST19. Our...

  12. Duplication of Hemolysin Genes in a Virulent Isolate of Vibrio harveyi

    Science.gov (United States)

    Zhang, X.-H.; Meaden, P. G.; Austin, B.

    2001-01-01

    Vibrio harveyi VIB 645, which is very pathogenic towards salmonids and produces extracellular product with a high titer of hemolytic activity towards fish erythrocytes, was found to contain two closely related hemolysin genes (designated vhhA and vhhB), whereas the majority of strains examined (11 of 13) carried only a single hemolysin gene. Both genes from VIB 645 were cloned and sequenced. The open reading frames (ORFs) of vhhA and vhhB shared a high level of identity (98.8%) and were predicted to encode identical polypeptides comprising 418 amino acid residues. The VHH protein shows homology to the lecithinase of V. mimicus and V. cholerae. Transformants of Escherichia coli containing the ORF of either vhhA or vhhB displayed weak hemolytic activity in rainbow trout blood agar. The hemolytic activity was very high when the ORF of vhhB was cloned in E. coli together with the native promoter. Surprisingly, the level of vhh-specific RNA transcript produced by VIB 645 was found to be very low. We conclude that the hemolytic phenotype of VIB 645 is not due to increased expression of one or both copies of the vhh gene. PMID:11425736

  13. Who Possesses Drug Resistance Genes in the Aquatic Environment? : Sulfamethoxazole (SMX) Resistance Genes among the Bacterial Community in Water Environment of Metro-Manila, Philippines

    OpenAIRE

    Satoru eSuzuki; Mitsuko eOgo; Miller, Todd W.; Akiko eShimizu; Hideshige eTakada; Maria Auxilia eSiringan

    2013-01-01

    Recent evidence has shown that antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are ubiquitous in natural environments, including sites considered pristine. To understand the origin of ARGs and their dynamics, we must first define their actual presence in the natural bacterial assemblage. Here we found varying distribution profiles of sul genes in “colony forming bacterial assemblages” and “natural bacterial assemblages.” Our monitoring for antibiotic contamination r...

  14. Systematic mutagenesis of genes encoding predicted autotransported proteins of Burkholderia pseudomallei identifies factors mediating virulence in mice, net intracellular replication and a novel protein conferring serum resistance.

    Science.gov (United States)

    Lazar Adler, Natalie R; Stevens, Mark P; Dean, Rachel E; Saint, Richard J; Pankhania, Depesh; Prior, Joann L; Atkins, Timothy P; Kessler, Bianca; Nithichanon, Arnone; Lertmemongkolchai, Ganjana; Galyov, Edouard E

    2015-01-01

    Burkholderia pseudomallei is the causative agent of the severe tropical disease melioidosis, which commonly presents as sepsis. The B. pseudomallei K96243 genome encodes eleven predicted autotransporters, a diverse family of secreted and outer membrane proteins often associated with virulence. In a systematic study of these autotransporters, we constructed insertion mutants in each gene predicted to encode an autotransporter and assessed them for three pathogenesis-associated phenotypes: virulence in the BALB/c intra-peritoneal mouse melioidosis model, net intracellular replication in J774.2 murine macrophage-like cells and survival in 45% (v/v) normal human serum. From the complete repertoire of eleven autotransporter mutants, we identified eight mutants which exhibited an increase in median lethal dose of 1 to 2-log10 compared to the isogenic parent strain (bcaA, boaA, boaB, bpaA, bpaC, bpaE, bpaF and bimA). Four mutants, all demonstrating attenuation for virulence, exhibited reduced net intracellular replication in J774.2 macrophage-like cells (bimA, boaB, bpaC and bpaE). A single mutant (bpaC) was identified that exhibited significantly reduced serum survival compared to wild-type. The bpaC mutant, which demonstrated attenuation for virulence and net intracellular replication, was sensitive to complement-mediated killing via the classical and/or lectin pathway. Serum resistance was rescued by in trans complementation. Subsequently, we expressed recombinant proteins of the passenger domain of four predicted autotransporters representing each of the phenotypic groups identified: those attenuated for virulence (BcaA), those attenuated for virulence and net intracellular replication (BpaE), the BpaC mutant with defects in virulence, net intracellular replication and serum resistance and those displaying wild-type phenotypes (BatA). Only BcaA and BpaE elicited a strong IFN-γ response in a restimulation assay using whole blood from seropositive donors and were

  15. Detection, Virulence Gene Assessment and Antibiotic Resistance Pattern of O157 Enterohemorrhagic Escherichia coli in Tabriz, Iran

    Science.gov (United States)

    Akhi, Mohammad Taghi; Ostadgavahi, Ali Toloue; Ghotaslou, Reza; Asgharzadeh, Mohammad; Pirzadeh, Tahereh; Sorayaei Sowmesarayi, Vida; Memar, Mohammad Yousef

    2015-01-01

    Background: Shiga toxin-producing Escherichia coli (STEC) is a food-borne pathogen and infection with this organism causes illnesses such as bloody diarrhea, hemorrhagic colitis and hemolytic-uremic syndrome. Objectives: Considering the lack of any information about the prevalence rate and the antibiotic resistance pattern of O157:H7 serotype in Tabriz, finding answers to the above mentioned subjects was among the goals of this study. Materials and Methods: Two hundred E. coli strains from diarrheal or non-diarrheal stools of outpatients and hospitalized cases in Tabriz Imam Reza hospital were isolated between September and December 2014 using MacConkey agar and standard biochemical tests and then cultured on sorbitol MacConkey agar. The sorbitol-negative isolates were confirmed as the O157 serotype using O157 antisera. A multiplex polymerase chain reaction (PCR) method was used for the detection of stx-1, stx-2, eae, and mdh genes and the antibiotic resistance pattern of these isolates was determined using Kirby-Bauer method and clinical and laboratory standards institute (CLSI) standards. Results: Of the isolates 11 (5.5%) were sorbitol-negative, which were later analyzed by multiplex PCR and the results revealed that 2 (18.18%) isolates contained the stx-1 gene, 10 (90.91%) contained the stx-2 gene, and 5 (45.45%) contained the eae gene. The stx-2 and eae genes were the most commonly encountered virulence factors. All or most of the isolates were susceptible to ceftazidime (100%), gentamicin (100%), ciprofloxacin (100%), nalidixic acid (90.9%), trimetoprim sulfamethoxazole (90.9%), chloramphenicol (90.9%), ampicillin (81.8%), and cephalothin (72.7%). On the contrary, moderate susceptibility of the isolates to doxycycline (54.5%) was observed. Conclusions: Due to the low frequency of STEC O157 and the high susceptibility rates of the isolates to the tested antibiotics in this study, STEC O157 has not become a major problem in Tabriz yet, but comprehensive

  16. Study on isolation, molecular detection of virulence gene and antibiotic sensitivity pattern of Escherichia coli isolated from milk and milk products

    OpenAIRE

    M. N. Brahmbhatt; H. C. Thaker; J. B. Nayak; P. K. Virpari

    2013-01-01

    Aim: The study was undertaken to isolate pathogenic E. coli from milk and various milk products, detection of virulence gene using Polymerase chain reaction (PCR) and investigate their antibiotic sensitivity pattern. Materials and Methods: Altogether 250 milk and various milk products samples consisting of raw milk (50), cheese (50), ice-cream (50), mawa (50) and dahi (50) were collected from milk vendors, retail shops located in Anand city, under aseptic precautions. For the enrichment of th...

  17. Plasmid virulence gene expression induced by short-chain fatty acids in Salmonella dublin: identification of rpoS-dependent and rpo-S-independent mechanisms.

    OpenAIRE

    El-Gedaily, A; Paesold, G; Chen, C Y; Guiney, D G; Krause, M.

    1997-01-01

    The Salmonella plasmid virulence spvABCD genes are growth phase regulated and require RpoS for maximal expression in stationary phase. We identified a growth phase-independent expression of spv which is mediated by short-chain fatty acids. During this fatty acid-mediated expression of spv, RpoS is required for induction only during exponential phase. In stationary phase, an rpoS-independent mechanism is responsible for expression of spv.

  18. Molecular Cloning and Characterization of cgt, the Brucella abortus Cyclic β-1,2-Glucan Transporter Gene, and Its Role in Virulence

    OpenAIRE

    Roset, Mara S.; Ciocchini, Andrés E.; Ugalde, Rodolfo A.; Iñón de Iannino, Nora

    2004-01-01

    The animal pathogen Brucella abortus contains a gene cgt, which complemented Sinorhizobium meliloti nodule development (ndvA) and Agrobacterium tumefaciens chromosomal virulence (chvA) mutants. Complemented strains recovered the presence of anionic cyclic β-1,2-glucan, motility, tumor induction in A. tumefaciens, and nodule occupancy in S. meliloti, all traits strictly associated with the presence of cyclic β-1,2-glucan in the periplasm. Nucleotide sequencing revealed that B. abortus cgt cont...

  19. Antimicrobial resistance, virulence-associated genes, and pulsed-field gel electrophoresis profiles of Salmonella enterica subsp. enterica serovar Typhimurium isolated from piglets with diarrhea in Korea

    OpenAIRE

    Hur, Jin; Choi, Yoon Young; Park, Jong Ho; Jeon, Byung Woo; Lee, Hee Soo; Kim, Ae Ran; Lee, John Hwa

    2011-01-01

    Salmonella enterica subsp. enterica serovar Typhimurium was isolated from diarrheic piglets in 2 periods, 2000–2001 (n = 25) and 2005–2006 (n = 17). To compare the characteristics of the isolates collected during the 2 periods, all isolates were tested for antimicrobial resistance, the presence of virulence genes, and pulsed-field gel electrophoresis (PFGE) patterns. All 42 isolates were resistant to at least 1 of the 20 antimicrobials tested, and 39 (93%) were resistant to 2 or more antimicr...

  20. Inhibition of virulence gene expression in Rhodococcus fascians and Pseudomonas aeruginosa by flavonoïds isolated from the genera Dalbergia and Combretum

    OpenAIRE

    Rajaonson, Sanda

    2011-01-01

    Plants are continuously confronted with a multitude attack either abiotic but also biotic in nature. Interestingly, despite the abundance of bacteria that plant has to face, only few are able to induce death or disease in the host plant. It is therefore likely that, in addition to secondary metabolites with antimicrobial properties, plants also synthesize secondary metabolites which are able to inhibit the expression of virulence genes in bacteria without affecting either growth or viability,...

  1. Botrytis cinerea virulence is drastically reduced after disruption of chitin synthase class III gene (Bcchs3a).

    Science.gov (United States)

    Soulié, Marie-Christine; Perino, Claude; Piffeteau, Annie; Choquer, Mathias; Malfatti, Pierrette; Cimerman, Agnès; Kunz, Caroline; Boccara, Martine; Vidal-Cros, Anne

    2006-08-01

    Botrytis cinerea is an important phytopathogenic fungus requiring new methods of control. Chitin biosynthesis, which involves seven classes of chitin synthases, could be an attractive target. A fragment encoding one of the class III enzymes was used to disrupt the corresponding Bcchs3a gene in the B. cinerea genome. The resulting mutant exhibited a 39% reduction in its chitin content and an 89% reduction in its in vitro chitin synthase activity, compared with the wild-type strain. Bcchs3a mutant was not affected in its growth in liquid medium, neither in its production of sclerotia, micro- and macroconidia. In contrast, the mutant Bcchs3a was severely impaired in its growth on solid medium. Counterbalancing this defect in radial growth, Bcchs3a mutant presented a large increase in hyphal ramification, resulting in an enhanced aerial growth. Observations by different techniques of microscopy revealed a thick extracellular matrix around the hyphal tips. Moreover, Bcchs3a mutant had a largely reduced virulence on Vitis vinifera and Arabidopsis thaliana leaves. PMID:16882034

  2. Two distinct groups of porcine enteropathogenic Escherichia coli strains of serogroup O45 are revealed by comparative genomic hybridization and virulence gene microarray

    Directory of Open Access Journals (Sweden)

    Gannon Victor PJ

    2009-08-01

    Full Text Available Abstract Background Porcine enteropathogenic Escherichia coli (PEPEC strains of serogroup O45 cause post-weaning diarrhea and produce characteristic attaching and effacing (A/E lesions. Most O45 PEPEC strains possess the locus of enterocyte effacement (LEE, encoding the virulence factors required for production of A/E lesions, and often possess the paa gene, which is thought to contribute to the early stages of PEPEC pathogenicity. In this study, nine O45 PEPEC strains and a rabbit enteropathogenic (REPEC strain, known to produce A/E lesions in vivo, were characterized using an E. coli O157-E. coli K12 whole genome microarray and a virulence gene-specific microarray, and by PCR experiments. Results Based on their virulence gene profiles, the 10 strains were considered to be atypical EPEC. The differences in their genomes pointed to the identification of two distinct evolutionary groups of O45 PEPEC, Groups I and II, and provided evidence for a contribution of these genetic differences to their virulence in pigs. Group I included the REPEC strain and four O45 PEPEC strains known to induce severe A/E lesions in challenged pigs whereas Group II was composed of the five other O45 PEPEC strains, which induced less severe or no A/E lesions in challenged pigs. Significant differences between Groups I and II were found with respect to the presence or absence of 50 O-Islands (OIs or S-loops and 13 K-islands (KIs or K-loops, including the virulence-associated islands OI#1 (S-loop#1, OI#47 (S-loop#71, OI#57 (S-loop#85, OI#71 (S-loop#108, OI#115, OI#122, and OI#154 (S-loop#253. Conclusion We have genetically characterized a collection of O45 PEPEC strains and classified them into two distinct groups. The differences in their virulence gene and genomic island content may influence the pathogenicity of O45 PEPEC strains, and explain why Group I O45 PEPEC strains induced more severe A/E lesions in explants and challenged pigs than Group II strains.

  3. Distribution of virulence genes sefC, pefA and spvC in Salmonella Enteritidis phage type 4 strains isolated in Brazil Distribuição de genes de virulência sefC, pefA e spvC em cepas de Salmonella Enteritidis fago tipo 4 isoladas no Brasil

    OpenAIRE

    Karina Salvagni Castilla; Claudete Serrano Astolfi Ferreira; Andrea Micke Moreno; Iolanda Aparecida Nunes; Antônio José Piantino Ferreira

    2006-01-01

    The distribution of virulence genes, sefC, pefA and spvC, was investigated in 110 Salmonella Enteritidis phage type 4 strains by polymerase chain reaction. Their influence in the caecal colonization and invasion of liver and spleen of one-day-old chickens was studied. Eight isolates were negative for the spvC gene, three for the pefA gene and one, for the sefC gene. These results allowed grouping the strains into four genotypes. Presence of these genes did not influence bacteria invasion in t...

  4. UreR, the transcriptional activator of the Proteus mirabilis urease gene cluster, is required for urease activity and virulence in experimental urinary tract infections.

    Science.gov (United States)

    Dattelbaum, Jonathan D; Lockatell, C Virginia; Johnson, David E; Mobley, Harry L T

    2003-02-01

    Proteus mirabilis, a cause of complicated urinary tract infection, produces urease, an essential virulence factor for this species. UreR, a member of the AraC/XylS family of transcriptional regulators, positively activates expression of the ure gene cluster in the presence of urea. To specifically evaluate the contribution of UreR to urease activity and virulence in the urinary tract, a ureR mutation was introduced into P. mirabilis HI4320 by homologous recombination. The isogenic ureR::aphA mutant, deficient in UreR production, lacked measurable urease activity. Expression was not detected in the UreR-deficient strain by Western blotting with monoclonal antibodies raised against UreD. Urease activity and UreD expression were restored by complementation of the mutant strain with ureR expressed from a low-copy-number plasmid. Virulence was assessed by transurethral cochallenge of CBA mice with wild-type and mutant strains. The isogenic ureR::aphA mutant of HI4320 was outcompeted in the urine (P = 0.004), bladder (P = 0.016), and kidneys (P urease activity in the absence of urea, for induction of urease by urea, and for virulence of P. mirabilis in the urinary tract. PMID:12540589

  5. Ongoing Horizontal and Vertical Transmission of Virulence Genes and papA Alleles among Escherichia coli Blood Isolates from Patients with Diverse-Source Bacteremia

    Science.gov (United States)

    Johnson, James R.; O'Bryan, Timothy T.; Kuskowski, Michael; Maslow, Joel N.

    2001-01-01

    The phylogenetic distributions of multiple putative virulence factors (VFs) and papA (P fimbrial structural subunit) alleles among 182 Escherichia coli blood isolates from patients with diverse-source bacteremia were defined. Phylogenetic correspondence among these strains, the E. coli Reference (ECOR) collection, and other collections of extraintestinal pathogenic E. coli (ExPEC) was assessed. Although among the 182 bacteremia isolates phylogenetic group B2 predominated, exhibited the greatest concentration of individual VFs, and contained the largest number of familiar virulent clones, other phylogenetic groups exhibited greater concentrations of certain VFs than did group B2 and included several additional virulent clones. Certain of the newly detected VF genes, e.g., fyuA (yersiniabactin; 76%) and focG (F1C fimbriae; 25%), were as prevalent or more prevalent than their more familiar traditional counterparts, e.g., iut (aerobactin; 57%) and sfaS (S fimbriae; 14%), thus possibly offering additional useful targets for preventive interventions. Considerable diversity of VF profiles was observed at every level within the phylogenetic tree, including even within individual lineages. This suggested that many different pathways can lead to extraintestinal virulence in E. coli and that the evolution of ExPEC, which involves extensive horizontal transmission of VFs and continuous remodeling of pathogenicity-associated islands, is a highly active, ongoing process. PMID:11500406

  6. Complementation of Listeria monocytogenes Null Mutants with Selected Listeria seeligeri Virulence Genes Suggests Functional Adaptation of Hly and PrfA and Considerable Diversification of prfA Regulation in L. seeligeri▿ †

    OpenAIRE

    Lucas Stelling, Courtney R.; Orsi, Renato H.; Wiedmann, Martin

    2010-01-01

    While Listeria seeligeri and L. monocytogenes contain the main Listeria virulence gene cluster, only L. monocytogenes is considered an intracellular pathogen. Initial evolutionary analyses showed that the virulence genes prfA, hly, and plcA are conserved in L. seeligeri, with specific Hly and PrfA amino acid residues showing evidence for positive selection in L. seeligeri. Our data also show that temperature-dependent transcript patterns for prfA, which encodes a transcriptional regulator of ...

  7. Strategies used for genetically modifying bacterial genome: ite-directed mutagenesis, gene inactivation, and gene over-expression*

    Science.gov (United States)

    Xu, Jian-zhong; Zhang, Wei-guo

    2016-01-01

    With the availability of the whole genome sequence of Escherichia coli or Corynebacterium glutamicum, strategies for directed DNA manipulation have developed rapidly. DNA manipulation plays an important role in understanding the function of genes and in constructing novel engineering bacteria according to requirement. DNA manipulation involves modifying the autologous genes and expressing the heterogenous genes. Two alternative approaches, using electroporation linear DNA or recombinant suicide plasmid, allow a wide variety of DNA manipulation. However, the over-expression of the desired gene is generally executed via plasmid-mediation. The current review summarizes the common strategies used for genetically modifying E. coli and C. glutamicum genomes, and discusses the technical problem of multi-layered DNA manipulation. Strategies for gene over-expression via integrating into genome are proposed. This review is intended to be an accessible introduction to DNA manipulation within the bacterial genome for novices and a source of the latest experimental information for experienced investigators. PMID:26834010

  8. Strategies used for genetically modifying bacterial genome: site-directed mutagenesis, gene inactivation, and gene over-expression.

    Science.gov (United States)

    Xu, Jian-zhong; Zhang, Wei-guo

    2016-02-01

    With the availability of the whole genome sequence of Escherichia coli or Corynebacterium glutamicum, strategies for directed DNA manipulation have developed rapidly. DNA manipulation plays an important role in understanding the function of genes and in constructing novel engineering bacteria according to requirement. DNA manipulation involves modifying the autologous genes and expressing the heterogenous genes. Two alternative approaches, using electroporation linear DNA or recombinant suicide plasmid, allow a wide variety of DNA manipulation. However, the over-expression of the desired gene is generally executed via plasmid-mediation. The current review summarizes the common strategies used for genetically modifying E. coli and C. glutamicum genomes, and discusses the technical problem of multi-layered DNA manipulation. Strategies for gene over-expression via integrating into genome are proposed. This review is intended to be an accessible introduction to DNA manipulation within the bacterial genome for novices and a source of the latest experimental information for experienced investigators. PMID:26834010

  9. The dual oxidase gene BdDuox regulates the intestinal bacterial community homeostasis of Bactrocera dorsalis.

    Science.gov (United States)

    Yao, Zhichao; Wang, Ailin; Li, Yushan; Cai, Zhaohui; Lemaitre, Bruno; Zhang, Hongyu

    2016-05-01

    The guts of metazoans are in permanent contact with the microbial realm that includes beneficial symbionts, nonsymbionts, food-borne microbes and life-threatening pathogens. However, little is known concerning how host immunity affects gut bacterial community. Here, we analyze the role of a dual oxidase gene (BdDuox) in regulating the intestinal bacterial community homeostasis of the oriental fruit fly Bactrocera dorsalis. The results showed that knockdown of BdDuox led to an increased bacterial load, and to a decrease in the relative abundance of Enterobacteriaceae and Leuconostocaceae bacterial symbionts in the gut. The resulting dysbiosis, in turn, stimulates an immune response by activating BdDuox and promoting reactive oxygen species (ROS) production that regulates the composition and structure of the gut bacterial community to normal status by repressing the overgrowth of minor pathobionts. Our results suggest that BdDuox plays a pivotal role in regulating the homeostasis of the gut bacterial community in B. dorsalis. PMID:26565723

  10. Lateral organ boundaries 1 is a disease susceptibility gene for citrus bacterial canker disease.

    Science.gov (United States)

    Hu, Yang; Zhang, Junli; Jia, Hongge; Sosso, Davide; Li, Ting; Frommer, Wolf B; Yang, Bing; White, Frank F; Wang, Nian; Jones, Jeffrey B

    2014-01-28

    Citrus bacterial canker (CBC) disease occurs worldwide and incurs considerable costs both from control measures and yield losses. Bacteria that cause CBC require one of six known type III transcription activator-like (TAL) effector genes for the characteristic pustule formation at the site of infection. Here, we show that Xanthomonas citri subspecies citri strain Xcc306, with the type III TAL effector gene pthA4 or with the distinct yet biologically equivalent gene pthAw from strain XccA(w), induces two host genes, CsLOB1 and CsSWEET1, in a TAL effector-dependent manner. CsLOB1 is a member of the Lateral Organ Boundaries (LOB) gene family of transcription factors, and CsSWEET1 is a homolog of the SWEET sugar transporter and rice disease susceptibility gene. Both TAL effectors drive expression of CsLOB1 and CsSWEET1 promoter reporter gene fusions when coexpressed in citrus or Nicotiana benthamiana. Artificially designed TAL effectors directed to sequences in the CsLOB1 promoter region, but not the CsSWEET1 promoter, promoted pustule formation and higher bacterial leaf populations. Three additional distinct TAL effector genes, pthA*, pthB, and pthC, also direct pustule formation and expression of CsLOB1. Unlike pthA4 and pthAw, pthB and pthC do not promote the expression of CsSWEET1. CsLOB1 expression was associated with the expression of genes associated with cell expansion. The results indicate that CBC-inciting species of Xanthomonas exploit a single host disease susceptibility gene by altering the expression of an otherwise developmentally regulated gene using any one of a diverse set of TAL effector genes in the pathogen populations. PMID:24474801

  11. More than 9,000,000 unique genes in human gut bacterial community: estimating gene numbers inside a human body.

    Directory of Open Access Journals (Sweden)

    Xing Yang

    Full Text Available BACKGROUND: Estimating the number of genes in human genome has been long an important problem in computational biology. With the new conception of considering human as a super-organism, it is also interesting to estimate the number of genes in this human super-organism. PRINCIPAL FINDINGS: We presented our estimation of gene numbers in the human gut bacterial community, the largest microbial community inside the human super-organism. We got 552,700 unique genes from 202 complete human gut bacteria genomes. Then, a novel gene counting model was built to check the total number of genes by combining culture-independent sequence data and those complete genomes. 16S rRNAs were used to construct a three-level tree and different counting methods were introduced for the three levels: strain-to-species, species-to-genus, and genus-and-up. The model estimates that the total number of genes is about 9,000,000 after those with identity percentage of 97% or up were merged. CONCLUSION: By combining completed genomes currently available and culture-independent sequencing data, we built a model to estimate the number of genes in human gut bacterial community. The total number of genes is estimated to be about 9 million. Although this number is huge, we believe it is underestimated. This is an initial step to tackle this gene counting problem for the human super-organism. It will still be an open problem in the near future. The list of genomes used in this paper can be found in the supplementary table.

  12. Nitrate Assimilation Contributes to Ralstonia solanacearum Root Attachment, Stem Colonization, and Virulence

    OpenAIRE

    Dalsing, Beth L.; Allen, Caitilyn

    2014-01-01

    Ralstonia solanacearum, an economically important plant pathogen, must attach, grow, and produce virulence factors to colonize plant xylem vessels and cause disease. Little is known about the bacterial metabolism that drives these processes. Nitrate is present in both tomato xylem fluid and agricultural soils, and the bacterium's gene expression profile suggests that it assimilates nitrate during pathogenesis. A nasA mutant, which lacks the gene encoding the catalytic subunit of R. solanacear...

  13. Dual role of RsmA in the coordinated regulation of expression of virulence genes in Pectobacterium wasabiae strain SCC3193.

    Science.gov (United States)

    Andresen, Liis; Frolova, Jekaterina; Põllumaa, Lee; Mäe, Andres

    2015-11-01

    The CsrA/RsmA family of post-transcriptional regulators in bacteria is involved in regulating many cellular processes, including pathogenesis. Using a bioinformatics approach, we identified an RsmA binding motif, A(N)GGA, in the Shine-Dalgarno regions of 901 genes. Among these genes with the predicted RsmA binding motif, 358 were regulated by RsmA according to our previously published gene expression profiling analysis (WT vs rsmA negative mutant; Kõiv et al., 2013). A small subset of the predicted targets known to be important as virulence factors was selected for experimental validation. RNA footprint analyses demonstrated that RsmA binds specifically to the ANGGA motif in the 5'UTR sequences of celV1, pehA, pelB, pel2 and prtW. RsmA-dependent regulation of these five genes was examined in vivo using plasmid-borne translational and transcriptional fusions with a reporter gusA gene. They were all affected negatively by RsmA. However, we demonstrated that whereas the overall effect of RsmA on celV1 and prtW was determined on both the translational and transcriptional level, expression of pectinolytic enzyme genes (pehA, pel2 and pelB) was affected mainly on the level of transcription in tested conditions. In summary, these data indicate that RsmA controls virulence by integration of its regulatory activities at various levels. PMID:26306750

  14. Construction and evaluation of live attenuated myxoma virus vaccines with targeted virulence gene deletions.

    Science.gov (United States)

    Adams, Mathew M; van Leeuwen, Barbara H; Kerr, Peter J

    2008-10-29

    Three deletion mutant viruses were constructed as potential vaccines against myxomatosis using the naturally attenuated Uriarra strain of myxoma virus. The viruses had the M007 (encodes a secreted gamma-interferon receptor homologue), M010 (encodes an epidermal growth factor homologue) and M011 (encodes an inhibitor of apoptosis in T lymphocytes) genes insertionally inactivated as either DeltaM007, DeltaM010/M011 or DeltaM007/M010/M011. All three viruses induced high serum antibody titres. Rabbits immunized with these deletion mutants were protected from lethal challenge. However, immunization of adult rabbits with DeltaM007 or DeltaM010/M011 was associated with mild clinical signs that would make these viruses unacceptable as vaccines. The triple gene knock-out virus (DeltaM007/M010/M011) termed Ur-TKO was very well tolerated by adult and juvenile rabbits. The low pathogenicity of Ur-TKO was confirmed by pathogenesis studies in domestic and wild rabbits. PMID:18789367

  15. Prevalence of virulence and antimicrobial resistance genes in Salmonella spp. isolated from commercial chickens and human clinical isolates from South Africa and Brazil

    Directory of Open Access Journals (Sweden)

    Oliver T. Zishiri

    2016-03-01

    Full Text Available Salmonellosis is a significant public health concern around the world. The injudicious use of antimicrobial agents in poultry production for treatment, growth promotion and prophylaxis has resulted in the emergence of drug resistant strains of Salmonella. The current study was conducted to investigate the prevalence of virulence and antimicrobial resistance genes from Salmonella isolated from South African and Brazilian broiler chickens as well as human clinical isolates. Out of a total of 200 chicken samples that were collected from South Africa 102 (51% tested positive for Salmonella using the InvA gene. Of the overall 146 Salmonella positive samples that were screened for the iroB gene most of them were confirmed to be Salmonella enterica with the following prevalence rates: 85% of human clinical samples, 68.6% of South African chicken isolates and 70.8% of Brazilian chicken samples. All Salmonella isolates obtained were subjected to antimicrobial susceptibility testing with 10 antibiotics. Salmonella isolates from South African chickens exhibited resistance to almost all antimicrobial agents used, such as tetracycline (93%, trimethoprim-sulfamthoxazole (84%, trimethoprim (78.4%, kanamycin (74%, gentamicin (48%, ampicillin (47%, amoxicillin (31%, chloramphenicol (31%, erythromycin (18% and streptomycin (12%. All samples were further subjected to PCR in order to screen some common antimicrobial and virulence genes of interest namely spiC, pipD, misL, orfL, pse-1, tet A, tet B, ant (3"-la, sul 1 and sul. All Salmonella positive isolates exhibited resistance to at least one antimicrobial agent; however, antimicrobial resistance patterns demonstrated that multiple drug resistance was prevalent. The findings provide evidence that broiler chickens are colonised by pathogenic Salmonella harbouring antimicrobial resistance genes. Therefore, it is evident that there is a need for prudent use of antimicrobial agents in poultry production systems in

  16. Virulence-related Mycobacterium avium subsp hominissuis MAV_2928 gene is associated with vacuole remodeling in macrophages

    Directory of Open Access Journals (Sweden)

    Vogt Steven

    2010-04-01

    Full Text Available Abstract Background Mycobacterium avium subsp hominissuis (previously Mycobacterium avium subsp avium is an environmental organism associated with opportunistic infections in humans. Mycobacterium hominissuis infects and replicates within mononuclear phagocytes. Previous study characterized an attenuated mutant in which the PPE gene (MAV_2928 homologous to Rv1787 was inactivated. This mutant, in contrast to the wild-type bacterium, was shown both to have impaired the ability to replicate within macrophages and to have prevented phagosome/lysosome fusion. Results MAV_2928 gene is primarily upregulated upon phagocytosis. The transcriptional profile of macrophages infected with the wild-type bacterium and the mutant were examined using DNA microarray, which showed that the two bacteria interact uniquely with mononuclear phagocytes. Based on the results, it was hypothesized that the phagosome environment and vacuole membrane of the wild-type bacterium might differ from the mutant. Wild-type bacterium phagosomes expressed a number of proteins different from those infected with the mutant. Proteins on the phagosomes were confirmed by fluorescence microscopy and Western blot. The environment in the phagosome of macrophages infected with the mutant differed from the environment of vacuoles with M. hominissuis wild-type in the concentration of zinc, manganese, calcium and potassium. Conclusion The results suggest that the MAV_2928 gene/operon might participate in the establishment of bacterial intracellular environment in macrophages.

  17. Cloning of a peroxidase gene from cassava with potential as a molecular marker for resistance to bacterial blight

    OpenAIRE

    Luiz Filipe Pereira; Goodwin, Paul H.; Larry Erickson

    2003-01-01

    Cassava bacterial blight (CBB), caused by Xanthomonas axonopodis pv. manihotis, is considered one of the most important bacterial diseases of cassava (Manihot esculenta Crantz). In order to characterize the cassava genes involved in resistance to this disease, a genomic clone of a cationic peroxidase gene, MEPX1, was isolated by PCR from cassava cultivar MCOL 22. The DNA sequence of MEPX1 showed high homology with other plant peroxidase genes and contained a large intron typical of peroxidase...

  18. Co2+-dependent gene expression in Streptococcus pneumoniae: opposite effect of Mn2+ and Co2+ on the expression of the virulence genes psaBCA, pcpA, and prtA

    OpenAIRE

    Manzoor, Irfan; Shafeeq, Sulman; Kloosterman, Tomas G.; Oscar P. Kuipers

    2015-01-01

    Manganese (Mn2+)-, zinc (Zn2+)- and copper (Cu2+) play significant roles in transcriptional gene regulation, physiology, and virulence of Streptococcus pneumoniae. So far, the effect of the important transition metal ion cobalt (Co2+) on gene expression of S. pneumoniae has not yet been explored. Here, we study the impact of Co2+ stress on the transcriptome of S. pneumoniae strain D39. BLAST searches revealed that the genome of S. pneumoniae encodes a putative Co2+-transport operon (cbi opero...

  19. Co2+-dependent gene expression in Streptococcus pneumoniae: Opposite effect of Mn2+ and Co2+ on the expression of the virulence genes psaBCA, pcpA and prtA

    OpenAIRE

    Irfan eManzoor; Sulman eShafeeq; Kloosterman, Tomas G.; Oscar P. Kuipers

    2015-01-01

    Manganese (Mn2+)-, zinc (Zn2+)- and copper (Cu2+) play significant roles in transcriptional gene regulation, physiology and virulence of Streptococcus pneumoniae. So far, the effect of the important transition metal ion cobalt (Co2+) on gene expression of S. pneumoniae has not yet been explored. Here, we study the impact of Co2+ stress on the transcriptome of S. pneumoniae strain D39. BLAST searches revealed that the genome of S. pneumoniae encodes a putative Co2+-transport operon (cbi operon...

  20. Characterization of a Legionella pneumophila relA Insertion Mutant and Roles of RelA and RpoS in Virulence Gene Expression

    OpenAIRE

    Zusman, Tal; Gal-Mor, Ohad; Segal, Gil

    2002-01-01

    To investigate the involvement of RelA in the regulation of Legionella pneumophila virulence, a deletion substitution was constructed in the relA gene. The relA knockout resulted in an undetectable level of ppGpp in the cells during the stationary phase, but the original level was restored when the relA gene product was supplied on a plasmid. The effect of the relA mutation was examined with two systems that are known to be expressed during the stationary phase in L. pneumophila. Pigment prod...

  1. Escherichia coli O157:H7 stress and virulence gene expression on Romaine lettuce using comparative real-time PCR.

    Science.gov (United States)

    Carey, Christine M; Kostrzynska, Magdalena; Thompson, Stacey

    2009-05-01

    Foodborne outbreaks attributed to the contamination of fresh produce with Escherichia coli O157:H7 are a growing concern. In particular, leafy-green vegetables, including lettuce and spinach, are susceptible to contamination by irrigation water, manure, and food processing and storage practices. The survival of E. coli O157:H7 and natural microflora on Romaine lettuce stored at 4 degrees C and 15 degrees C over a 9-day period was evaluated by plate counts. A two-step reverse-transcription comparative quantitative real-time PCR assay was employed to evaluate expression of genes coding for the A subunit of Shiga-toxin 1 and 2 (stx1A and stx2A), intimin (eaeA), flagellin (fliC), sigmaS--general stress sigma factor (rpoS) and iron superoxide dismutase (sodB) in E. coli O157:H7. Results indicate that reducing the storage temperature from 15 degrees C to 4 degrees C significantly (P<0.05) reduced the growth of Escherichia coli O157:H7 on Romaine lettuce, however, viable populations remained after the end of both storage periods. At end of the storage period, a 0.430 and 0.180 log decrease in E. coli O157:H7 was observed at 4 degrees C and 15 degrees C, respectively. Under both storage temperatures, total aerobic plate counts increased over the duration of the experiment. An increase in E. coli O157:H7 fold expression was observed with stx2A. Although stx1A exhibited upregulation for all storage conditions, variable gene expression was observed throughout the storage period. In addition, fliC was up-regulated during storage at 15 degrees C, while transcription at 4 degrees C storage changed only slightly. Expression of eaeA was variable at 15 degrees C with a tendency towards down-regulation, however, this gene was slightly up-regulated when stored at 4 degrees C. A slight upregulation of rpoS and sodB was also observed at 4 degrees C. In conclusion, our results suggest E. coli O157:H7 may become more virulent with prolonged storage of Romaine lettuce, particularly when

  2. Pyruvate kinase is necessary for Brucella abortus full virulence in BALB/c mouse.

    Science.gov (United States)

    Gao, Jianpeng; Tian, Mingxing; Bao, Yanqing; Li, Peng; Liu, Jiameng; Ding, Chan; Wang, Shaohui; Li, Tao; Yu, Shengqing

    2016-01-01

    Brucellosis, caused by a facultative intracellular pathogen Brucella, is one of the most prevalent zoonosis worldwide. Host infection relies on several uncanonical virulence factors. A recent research hotpot is the links between carbon metabolism and bacterial virulence. In this study, we found that a carbon metabolism-related pyruvate kinase (Pyk) encoded by pyk gene (locus tag BAB_RS24320) was associated with Brucella virulence. Determination of bacterial growth curves and resistance to environmental stress factors showed that Pyk plays an important role in B. abortus growth, especially under the conditions of nutrition deprivation, and resistance to oxidative stress. Additionally, cell infection assay showed that Pyk is necessary for B. abortus survival and evading fusion with lysosomes within RAW264.7 cells. Moreover, animal experiments exhibited that the Pyk deletion significantly reduced B. abortus virulence in a mouse infection model. Our results elucidated the role of the Pyk in B. abortus virulence and provided information for further investigation of Brucella virulence associated carbon metabolism. PMID:27561260

  3. Occurrence of virulence genes associated with diarrheagenic Escherichia coli isolated from raw cow's milk from two commercial dairy farms in the Eastern Cape Province, South Africa.

    Science.gov (United States)

    Caine, Lesley-Anne; Nwodo, Uchechukwu U; Okoh, Anthony I; Ndip, Roland N; Green, Ezekiel

    2014-11-01

    Escherichia coli remains a public health concern worldwide as an organism that causes diarrhea and its reservoir in raw milk may play an important role in the survival and transport of pathogenic strains. Diarrheagenic E. coli strains are diverse food-borne pathogens and causes diarrhea with varying virulence in humans. We investigated the prevalence of pathogenic E. coli in raw milk from two commercial dairy farms. Four hundred raw milk samples, 200 from each dairy farm, were screened for the presence of fliCH7, eagR, ial, eagg, lt, and papC genes. In dairy farm A, 100 E. coli were identified based on culture, oxidase and Gram staining, while 88 isolates from dairy farm B were identified in the same manner. Gene detection showed fliCH7 27 (54%) to be the highest gene detected from farm A and lt 2 (4%) to be the lowest. The highest gene detected in dairy farm B was fliCH7 16 (43.2%) and papC 1 (2.7%) was the least. The amplification of pathogenic genes associated with diarrheagenic E. coli from cows' raw milk demonstrates that potentially virulent E. coli strains are widely distributed in raw milk and may be a cause of concern for human health. PMID:25411727

  4. Occurrence of Virulence Genes Associated with Diarrheagenic Escherichia coli Isolated from Raw Cow’s Milk from Two Commercial Dairy Farms in the Eastern Cape Province, South Africa

    Directory of Open Access Journals (Sweden)

    Lesley-Anne Caine

    2014-11-01

    Full Text Available Escherichia coli remains a public health concern worldwide as an organism that causes diarrhea and its reservoir in raw milk may play an important role in the survival and transport of pathogenic strains. Diarrheagenic E. coli strains are diverse food-borne pathogens and causes diarrhea with varying virulence in humans. We investigated the prevalence of pathogenic E. coli in raw milk from two commercial dairy farms. Four hundred raw milk samples, 200 from each dairy farm, were screened for the presence of fliCH7, eagR, ial, eagg, lt, and papC genes. In dairy farm A, 100 E. coli were identified based on culture, oxidase and Gram staining, while 88 isolates from dairy farm B were identified in the same manner. Gene detection showed fliCH7 27 (54% to be the highest gene detected from farm A and lt 2 (4% to be the lowest. The highest gene detected in dairy farm B was fliCH7 16 (43.2% and papC 1 (2.7% was the least. The amplification of pathogenic genes associated with diarrheagenic E. coli from cows’ raw milk demonstrates that potentially virulent E. coli strains are widely distributed in raw milk and may be a cause of concern for human health.

  5. Virulence Factors of Erwinia amylovora: A Review

    Directory of Open Access Journals (Sweden)

    Núria Piqué

    2015-06-01

    Full Text Available Erwinia amylovora, a Gram negative bacteria of the Enterobacteriaceae family, is the causal agent of fire blight, a devastating plant disease affecting a wide range of host species within Rosaceae and a major global threat to commercial apple and pear production. Among the limited number of control options currently available, prophylactic application of antibiotics during the bloom period appears the most effective. Pathogen cells enter plants through the nectarthodes of flowers and other natural openings, such as wounds, and are capable of rapid movement within plants and the establishment of systemic infections. Many virulence determinants of E. amylovora have been characterized, including the Type III secretion system (T3SS, the exopolysaccharide (EPS amylovoran, biofilm formation, and motility. To successfully establish an infection, E. amylovora uses a complex regulatory network to sense the relevant environmental signals and coordinate the expression of early and late stage virulence factors involving two component signal transduction systems, bis-(3′-5′-cyclic di-GMP (c-di-GMP and quorum sensing. The LPS biosynthetic gene cluster is one of the relatively few genetic differences observed between Rubus- and Spiraeoideae-infecting genotypes of E. amylovora. Other differential factors, such as the presence and composition of an integrative conjugative element associated with the Hrp T3SS (hrp genes encoding the T3SS apparatus, have been recently described. In the present review, we present the recent findings on virulence factors research, focusing on their role in bacterial pathogenesis and indicating other virulence factors that deserve future research to characterize them.

  6. Virulence Factors of Erwinia amylovora: A Review.

    Science.gov (United States)

    Piqué, Núria; Miñana-Galbis, David; Merino, Susana; Tomás, Juan M

    2015-01-01

    Erwinia amylovora, a Gram negative bacteria of the Enterobacteriaceae family, is the causal agent of fire blight, a devastating plant disease affecting a wide range of host species within Rosaceae and a major global threat to commercial apple and pear production. Among the limited number of control options currently available, prophylactic application of antibiotics during the bloom period appears the most effective. Pathogen cells enter plants through the nectarthodes of flowers and other natural openings, such as wounds, and are capable of rapid movement within plants and the establishment of systemic infections. Many virulence determinants of E. amylovora have been characterized, including the Type III secretion system (T3SS), the exopolysaccharide (EPS) amylovoran, biofilm formation, and motility. To successfully establish an infection, E. amylovora uses a complex regulatory network to sense the relevant environmental signals and coordinate the expression of early and late stage virulence factors involving two component signal transduction systems, bis-(3'-5')-cyclic di-GMP (c-di-GMP) and quorum sensing. The LPS biosynthetic gene cluster is one of the relatively few genetic differences observed between Rubus- and Spiraeoideae-infecting genotypes of E. amylovora. Other differential factors, such as the presence and composition of an integrative conjugative element associated with the Hrp T3SS (hrp genes encoding the T3SS apparatus), have been recently described. In the present review, we present the recent findings on virulence factors research, focusing on their role in bacterial pathogenesis and indicating other virulence factors that deserve future research to characterize them. PMID:26057748

  7. RegA, an AraC-like protein, is a global transcriptional regulator that controls virulence gene expression in Citrobacter rodentium.

    Science.gov (United States)

    Hart, Emily; Yang, Ji; Tauschek, Marija; Kelly, Michelle; Wakefield, Matthew J; Frankel, Gad; Hartland, Elizabeth L; Robins-Browne, Roy M

    2008-11-01

    Citrobacter rodentium is an attaching and effacing pathogen which causes transmissible colonic hyperplasia in mice. Infection with C. rodentium serves as a model for infection of humans with enteropathogenic and enterohemorrhagic Escherichia coli. To identify novel colonization factors of C. rodentium, we screened a signature-tagged mutant library of C. rodentium in mice. One noncolonizing mutant had a single transposon insertion in an open reading frame (ORF) which we designated regA because of its homology to genes encoding members of the AraC family of transcriptional regulators. Deletion of regA in C. rodentium resulted in markedly reduced colonization of the mouse intestine. Examination of lacZ transcriptional fusions using promoter regions of known and putative virulence-associated genes of C. rodentium revealed that RegA strongly stimulated transcription of two newly identified genes located close to regA, which we designated adcA and kfcC. The cloned adcA gene conferred autoaggregation and adherence to mammalian cells to E. coli strain DH5alpha, and a kfc mutation led to a reduction in the duration of intestinal colonization, but the kfc mutant was far less attenuated than the regA mutant. These results indicated that other genes of C. rodentium whose expression required activation by RegA were required for colonization. Microarray analysis revealed a number of RegA-regulated ORFs encoding proteins homologous to known colonization factors. Transcription of these putative virulence determinants was activated by RegA only in the presence of sodium bicarbonate. Taken together, these results show that RegA is a global regulator of virulence in C. rodentium which activates factors that are required for intestinal colonization. PMID:18765720

  8. In Candida parapsilosis the ATC1 gene encodes for an acid trehalase involved in trehalose hydrolysis, stress resistance and virulence.

    Directory of Open Access Journals (Sweden)

    Ruth Sánchez-Fresneda

    Full Text Available An ORF named CPAR2-208980 on contig 005809 was identified by screening a Candida parapsilosis genome data base. Its 67% identity with the acid trehalase sequence from C. albicans (ATC1 led us to designate it CpATC1. Homozygous mutants that lack acid trehalase activity were constructed by gene disruption at the two CpATC1 chromosomal alleles. Phenotypic characterization showed that atc1Δ null cells were unable to grow on exogenous trehalose as carbon source, and also displayed higher resistance to environmental challenges, such as saline exposure (1.2 M NaCl, heat shock (42°C and both mild and severe oxidative stress (5 and 50 mM H2O2. Significant amounts of intracellular trehalose were specifically stored in response to the thermal upshift in both wild type and mutant strains. Analysis of their antioxidant activities revealed that catalase was only triggered in response to heat shock in atc1Δ cells, whereas glutathione reductase was activated upon mild oxidative stress in wild type and reintegrant strains, and in response to the whole set of stress treatments in the homozygous mutant. Furthermore, yeast cells with double CpATC1 deletion were significantly attenuated in non-mammalian infection models, suggesting that CpATC1 is required for the pathobiology of the fungus. Our results demonstrate the involvement of CpAtc1 protein in the physiological hydrolysis of external trehalose in C. parapsilosis, where it also plays a major role in stress resistance and virulence.

  9. Mutations in polymerase genes enhanced the virulence of 2009 pandemic H1N1 influenza virus in mice.

    Directory of Open Access Journals (Sweden)

    Wenfei Zhu

    Full Text Available Influenza A virus can infect a wide variety of animal species with illness ranging from mild to severe, and is a continual cause for concern. Genetic mutations that occur either naturally or during viral adaptation in a poorly susceptible host are key mechanisms underlying the evolution and virulence of influenza A virus. Here, the variants containing PA-A36T or PB2-H357N observed in the mouse-adapted descendants of 2009 pandemic H1N1 virus (pH1N1, A/Sichuan/1/2009 (SC, were characterized. Both mutations enhanced polymerase activity in mammalian cells. These effects were confirmed using recombinant SC virus containing polymerase genes with wild type (WT or mutant PA or PB2. The PA-A36T mutant showed enhanced growth property compared to the WT in both human A549 cells and porcine PK15 cells in vitro, without significant effect on viral propagation in murine LA-4 cells and pathogenicity in mice; however, it did enhance the lung virus titer. PB2-H357N variant demonstrated growth ability comparable to the WT in A549 cells, but replicated well in PK15, LA-4 cells and in mice with an enhanced pathogenic phenotype. Despite such mutations are rare in nature, they could be observed in avian H5 and H7 subtype viruses which were currently recognized to pose potential threat to human. Our findings indicated that pH1N1 may adapt well in mammals when acquiring these mutations. Therefore, future molecular epidemiological surveillance should include scrutiny of both markers because of their potential impact on pathogenesis.

  10. [Progress in expression regulation of bacterial lipase genes--A review].

    Science.gov (United States)

    Zha, Daiming; Yan, Yunjun

    2015-11-01

    Microbial lipases are major sources of commercial ones, which have been extensively used in a wide variety of industrial fields, such as foods, beverages, lipids, detergents, feeds, textiles, leathers, advanced materials, fine chemicals, medicines, cosmetics, papermaking, pollution treatment, and bioenergy. Compared with fungal lipases, bacterial lipases have more types of reactions and exhibit higher activity and better stability in aqueous or organic phases. Amongst bacterial lipases, the most excellent ones are those originating from the genus Pseudomonas. So far, the conventional strategies, such as traditional breeding, optimization of medium and fermentation conditions, cannot fundamentally solve the problem of low production of bacterial lipases. Construction of genetically engineered strains to efficiently overexpress their own lipases is an effective solution. But it must base on clarifying molecular regulation mechanism of lipase gene expression and further finding out key regulators. In this article, we reviewed the progress in expression regulation of bacterial lipase genes from the aspects of direct regulators, quorum sensing system, Gac/Rsm signal transduction system, regulators controlling the Gac/Rsm system, and other regulators. To provide a useful reference for the construction of genetically engineered strains, we also discussed a research prospect in this field based on our ongoing research. PMID:26915218

  11. Ultra-deep pyrosequencing of partial surface protein genes from infectious Salmon Anaemia virus (ISAV suggest novel mechanisms involved in transition to virulence.

    Directory of Open Access Journals (Sweden)

    Turhan Markussen

    Full Text Available Uncultivable HPR0 strains of infectious salmon anaemia viruses (ISAVs infecting gills are non-virulent putative precursors of virulent ISAVs (vISAVs causing systemic disease in farmed Atlantic salmon (Salmo salar. The transition to virulence involves two molecular events, a deletion in the highly polymorphic region (HPR of the hemagglutinin-esterase (HE gene and a Q266→L266 substitution or insertion next to the putative cleavage site (R267 in the fusion protein (F. We have performed ultra-deep pyrosequencing (UDPS of these gene regions from healthy fish positive for HPR0 virus carrying full-length HPR sampled in a screening program, and a vISAV strain from an ISA outbreak at the same farming site three weeks later, and compared the mutant spectra. As the UDPS data shows the presence of both HE genotypes at both sampling times, and the outbreak strain was unlikely to be directly related to the HPR0 strain, this is the first report of a double infection with HPR0s and vISAVs. For F amplicon reads, mutation frequencies generating L266 codons in screening samples and Q266 codons in outbreak samples were not higher than at any random site. We suggest quasispecies heterogeneity as well as RNA structural properties are linked to transition to virulence. More specifically, a mechanism where selected single point mutations in the full-length HPR alter the RNA structure facilitating single- or sequential deletions in this region is proposed. The data provides stronger support for the deletion hypothesis, as opposed to recombination, as the responsible mechanism for generating the sequence deletions in HE.

  12. Emergence of Collective Territorial Defense in Bacterial Communities: Horizontal Gene Transfer Can Stabilize Microbiomes

    OpenAIRE

    János Juhász; Attila Kertész-Farkas; Dóra Szabó; Sándor Pongor

    2014-01-01

    Multispecies bacterial communities such as the microbiota of the gastrointestinal tract can be remarkably stable and resilient even though they consist of cells and species that compete for resources and also produce a large number of antimicrobial agents. Computational modeling suggests that horizontal transfer of resistance genes may greatly contribute to the formation of stable and diverse communities capable of protecting themselves with a battery of antimicrobial agents while preserving ...

  13. Host PGRP Gene Expression and Bacterial Release in Endosymbiosis of the Weevil Sitophilus zeamais

    OpenAIRE

    Anselme, Caroline; Vallier, Agnès; Balmand, Séverine; Fauvarque, Marie-Odile; Heddi, Abdelaziz

    2006-01-01

    Intracellular symbiosis (endosymbiosis) with gram-negative bacteria is common in insects, yet little is known about how the host immune system perceives the endosymbionts and controls their growth and invasion without complete bacterial clearance. In this study, we have explored the expression of a peptidoglycan recognition protein gene of the weevil Sitophilus zeamais (wPGRP); an ortholog in Drosophila (i.e., PGRP-LB) was recently shown to downregulate the Imd pathway (A. Zaidman-Remy, M. He...

  14. Housefly Larva Vermicomposting Efficiently Attenuates Antibiotic Resistance Genes in Swine Manure, with Concomitant Bacterial Population Changes

    OpenAIRE

    Wang, Hang; Li, Hongyi; Gilbert, Jack A.; Li, Haibo; Wu, Longhua; Liu, Meng; Wang, Liling; Zhou, Qiansheng; Yuan, Junxiang; Zhang, Zhijian

    2015-01-01

    Manure from swine treated with antimicrobials as feed additives is a major source for the expansion of the antibiotic resistance gene (ARG) reservoir in the environment. Vermicomposting via housefly larvae (Musca domestica) can be efficiently used to treat manure and regenerate biofertilizer, but few studies have investigated its effect on ARG attenuation. Here, we tracked the abundances of 9 ARGs and the composition and structure of the bacterial communities in manure samples across 6 days o...

  15. 四川省钩端螺旋体毒力相关基因研究%Study on the Virulence Associated Genes of Leptospires in Sichuan Province

    Institute of Scientific and Technical Information of China (English)

    曾林子; 郭宗琪; 曾义学; 祁腾; 刘谊; 刘莉莉; 罗隆泽

    2011-01-01

    Objective To study the factors related to the virulence associated genes of Leptospira in Sichuan province , provide scientific evidence for the prevention and control of Leptospirosis. Methods Seven putative virulence associated genes and group specific gene G1, C2 were detected by polymerase chain reaction (PCR) in the 90 field strains of Leptospira interrogans isolated in Sichuan province and from patients or animals between 1970 -2010, and 4 strains of Leptospira biflexas. Results In the 90 field strains, among 7 putative virulent genes, sphA detected rate was 6.67% , and the other 6 virulence associated genes detected rates were between 81. 1% to 98. 9%. Gl and G2 detected rate was 100%. Detection rates of those 8 genes were 0 in 4 strains of Leptospira bifiexa. Conclusion The virulence associated genes of Leprosies interrogans isolated from Sichuan province were widely distributed, and the detection rates were high. The virulence associated genes distributed in the strains isolated from Leptospira interrogans and from the patients or animals were quite identically.%目的 研究四川省问号钩端螺旋体(简称钩体)中毒力相关基因分布特点,为防治钩体病提供科学依据.方法根据钩体赖型赖株全基因组序列生物信息学资料,选择7个钩体致病相关基因与群特异性G1、G2基因,采用聚合酶链反应(PCR),对四川省1970 - 2010年分离保存的问号钩体90株和对照用双曲钩体4株,共94株进行了检测.结果90株问号钩体中7个毒力相关基因,除sphA基因检出率较低外(6.67%),其余6个毒力相关基因检出率在81.1%~98.9%之间,G1、G2基因检出率为100%,双曲钩体中未检测出7个毒力相关基因和G1、G2基因.结论四川省问号钩体中毒力相关基因分布广泛,检出率高,患者分离株与黑线姬鼠分离株毒力相关基因分布高度一致.

  16. Differential regulation of horizontally acquired and core genome genes by the bacterial modulator H-NS.

    Directory of Open Access Journals (Sweden)

    Rosa C Baños

    2009-06-01

    Full Text Available Horizontal acquisition of DNA by bacteria dramatically increases genetic diversity and hence successful bacterial colonization of several niches, including the human host. A relevant issue is how this newly acquired DNA interacts and integrates in the regulatory networks of the bacterial cell. The global modulator H-NS targets both core genome and HGT genes and silences gene expression in response to external stimuli such as osmolarity and temperature. Here we provide evidence that H-NS discriminates and differentially modulates core and HGT DNA. As an example of this, plasmid R27-encoded H-NS protein has evolved to selectively silence HGT genes and does not interfere with core genome regulation. In turn, differential regulation of both gene lineages by resident chromosomal H-NS requires a helper protein: the Hha protein. Tight silencing of HGT DNA is accomplished by H-NS-Hha complexes. In contrast, core genes are modulated by H-NS homoligomers. Remarkably, the presence of Hha-like proteins is restricted to the Enterobacteriaceae. In addition, conjugative plasmids encoding H-NS variants have hitherto been isolated only from members of the family. Thus, the H-NS system in enteric bacteria presents unique evolutionary features. The capacity to selectively discriminate between core and HGT DNA may help to maintain horizontally transmitted DNA in silent form and may give these bacteria a competitive advantage in adapting to new environments, including host colonization.

  17. Absence of co-localization between pathovar-associated virulence factors and extended-spectrum β-lactamase (blaCTX-M) genes on a single plasmid.

    Science.gov (United States)

    Valat, Charlotte; Forest, Karine; Billet, Méganne; Polizzi, Charlène; Saras, Estelle; Madec, Jean-Yves; Haenni, Marisa

    2016-08-30

    Extended-spectrum β-lactamases (ESBLs) were reported in virulent food-borne Escherichia coli clones, and numerous genes encoding ESBLs and virulence factors (VFs) are plasmid-mediated. We investigated the plasmidic co-localization of ESBL genes and pathovar-associated VF genes isolated in 18 E. coli isolates from faecal samples of diseased cattle. From the rare ESBL-producing E. coli among the various pathovars, no plasmid co-localization was found between VF and blaCTX-M genes on a single plasmid. However, a link between replicon types and VFs was highlighted: EspP was associated with IncFIB and ToxB with IncB/O. Associations of IncF alleles to VF or CTX-M-types were also identified: CS31A was linked to the allele FIB38 and CTX-M-14 to IncFII2. Also, as illustrated here, IncFII and IncFIB were carried by two different plasmids in a single cell. PMID:27527778

  18. Analysis of bone marrow stromal cell transferred bacterial β-galactosidase gene by PIXE

    International Nuclear Information System (INIS)

    PIXE, Particle Induced X-ray Emission, is a powerful, multi-elemental analysis method which has many distinguishing features and has been used in varies research fields. Recently the method of applying baby cyclotrons for nuclear medicine to PIXE has been developed. This enables us to study biomedical phenomena from the physical point of view. Mouse bone marrow stromal cells were transferred bacterial β-galactosidase gene (LacZ gene) by murine retroviral vectors. Analysis of the bone marrow stromal cells with the LacZ gene by PIXE revealed remarkable changes of intracellular trace elements compared with the normal control cells. These results indicate that gene transfer by retroviral vectors may bring about a dynamic change of intracellular circumstances of the target cell. (author)

  19. CONJUGAL GENE TRANSFER IN THE RHIZOSPHERE OF WATER GRASS (ECHINOCHLORA CRUSGALLI): INFLUENCE OF ROOT EXUDATE AND BACTERIAL ACTIVITY

    Science.gov (United States)

    The premise that genetic exchange is primarily localized in niches characterized by dense bacterial populations and high availability of growth substrates was tested by relating conjugal gene transfer of an RP4 derivative to availability of root exudates and bacterial metabolic a...

  20. Non-virulence of a recombinant shrimp nidovirus is associated with its non structural gene sequence and not a large structural gene deletion

    International Nuclear Information System (INIS)

    RT-PCR using a commercial kit for yellow head virus (YHV) detection in growth-retarded shrimp yielded an unusual 777 bp amplicon instead of expected amplicons of 277 bp for YHV type-1 (YHV-1) or 406 bp for YHV type-2 (YHV-2). Cloning and sequencing (GenBank (EU170438)) revealed approximately 80% identity to non-structural (NS) ORF1b sequences of both YHV-1 (GenBank (AA083987)) and YHV-2 (GenBank (AF227196)), indicating an atypical YHV type (A-YHV) phylogenetically equidistant from both types. An RT-PCR test specifically designed for A-YHV revealed that it was uncommon and that its occurrence in shrimp culture ponds did not correlate with growth retardation or mortality. By immunohistochemistry with YHV-specific monoclonal antibodies, the A-YHV gave positive reactions for envelope protein gp64 and capsid protein p20, but not for envelope protein gp116, even though gp116 and gp64 originate from a polyprotein of ORF3. Lack of gp116 immunoreactivity correlated with a large ORF3 deletion (GenBank (EU123854)) in the region of the protein targeted by an MAb against gp116. Transmission electron microscopy of A-YHV-infected shrimp revealed only unenveloped pre-virions. During manuscript revision, information received revealed that typing of YHV isolates based on sequences of ORF1b and ORF3 had yielded several geographical types, including one virulent type (YHV-1b) with an ORF3 deletion sequence that matched the sequence of A-YHV. Using these sequences and an additional A-YHV sequence ( (EU853170)) from the ORF1b typing region, A-YHV potentially represents a recombinant between type 1b and type 5. SDS-PAGE and Western blot analysis revealed that type 1b produced a gp116 deletion protein that did not bind with the MAb or polyclonal Ab to normal gp116. Overall, the information suggested that lack of A-YHV virulence was associated with the NS gene sequence linked to ORF1b rather than the deletion in ORF3

  1. Screening of virulence-associated genes as a molecular typing method for characterization of Streptococcus suis isolates recovered from wild boars and pigs.

    Science.gov (United States)

    Sánchez Del Rey, Verónica; Fernández-Garayzábal, José F; Domínguez, Lucas; Gottschalk, Marcelo; Vela, Ana I

    2016-03-01

    Streptococcus suis is an important zoonotic pathogen associated with a wide range of diseases in pigs, but has also been isolated from wild animals such as rabbits and wild boars. In the current study, 126 S. suis isolates recovered from pigs (n = 85) and wild boars (n = 41) were tested by polymerase chain reaction (PCR) for the presence of nine virulence-associated genes. S. suis isolates from wild boars were differentiated by the lower detection rates of the epf, sly, mrp, sao and dltA genes (0%, 2.4%, 2.4%, 4.8% and 21.9%, respectively) compared with the isolates from pigs (56.5%, 75.3%, 56.5%, 88.2.0% and 88.2%, respectively). The differences in the content of these virulence-associated genes were statistically significant (P < 0.05). There was a correlation between the variants saoM and saoL and serotypes 2 and 9, respectively (P < 0.05). Isolates were classified into 31 virulence-associated gene profiles (VPs). Ten VPs were detected among wild boar isolates and 22 VPs among pig isolates, with only two VPs common to wild boars and pigs. The predominant VPs among isolates from wild boars (VP1, VP7) were different from those observed in pig isolates (VP16 and VP26). VP16 was detected exclusively in clinical pig isolates of serotype 9 and VP26 was detected in 71.4% of the serotype 2 clinical pig isolates. Further multilocus sequence typing (MLST) analysis showed a significant correlation association between certain VPs and STs (VP16 and VP17 with ST123 and ST125 and VP26 with ST1). In conclusion, the current study showed that combination of virulence-associated gene profiling and MLST analysis may provide more information of the relatedness of the S. suis strains from different animal species that could be useful for epidemiological purposes. PMID:26831161

  2. Gene expression in gut symbiotic organ of stinkbug affected by extracellular bacterial symbiont.

    Directory of Open Access Journals (Sweden)

    Ryo Futahashi

    Full Text Available The bean bug Riptortus pedestris possesses a specialized symbiotic organ in a posterior region of the midgut, where numerous crypts harbor extracellular betaproteobacterial symbionts of the genus Burkholderia. Second instar nymphs orally acquire the symbiont from the environment, and the symbiont infection benefits the host by facilitating growth and by occasionally conferring insecticide resistance. Here we performed comparative transcriptomic analyses of insect genes expressed in symbiotic and non-symbiotic regions of the midgut dissected from Burkholderia-infected and uninfected R. pedestris. Expression sequence tag analysis of cDNA libraries and quantitative reverse transcription PCR identified a number of insect genes expressed in symbiosis- or aposymbiosis-associated patterns. For example, genes up-regulated in symbiotic relative to aposymbiotic individuals, including many cysteine-rich secreted protein genes and many cathepsin protease genes, are likely to play a role in regulating the symbiosis. Conversely, genes up-regulated in aposymbiotic relative to symbiotic individuals, including a chicken-type lysozyme gene and a defensin-like protein gene, are possibly involved in regulation of non-symbiotic bacterial infections. Our study presents the first transcriptomic data on gut symbiotic organ of a stinkbug, which provides initial clues to understanding of molecular mechanisms underlying the insect-bacterium gut symbiosis and sheds light on several intriguing commonalities between endocellular and extracellular symbiotic associations.

  3. Comparative analysis of agr groups and virulence genes among subclinical and clinical mastitis Staphylococcus aureus isolates from sheep flocks of the Northeast of Brazil

    Directory of Open Access Journals (Sweden)

    Lara M. de Almeida

    2013-01-01

    Full Text Available Staphylococcus aureus is one of the most frequent mastitis causative agents in small ruminants. The expression of most virulence genes of S. aureus is controlled by an accessory gene regulator (agrlocus. This study aimed to ascertain the prevalence of the different agr groups and to evaluate the occurrence of encoding genes for cytotoxin, adhesins and toxins with superantigen activity in S. aureus isolates from milk of ewes with clinical and subclinical mastitis in sheep flocks raised for meat production The agr groups I and II were identified in both cases of clinical and subclinical mastitis. Neither the arg groups III and IV nor negative agr were found. The presence of cflA gene was identified in 100% of the isolates. The frequency of hla and lukE-D genes was high -77.3 and 82.8%, respectively and all isolates from clinical mastitis presented these genes. The sec gene, either associated to tst gene or not, was identified only in isolates from subclinical mastitis. None of the following genes were identified: bbp, ebpS, cna, fnbB, icaA, icaD, bap, hlg, lukM-lukF-PV and se-a-b-d-e.

  4. Comparative analysis of agr groups and virulence genes among subclinical and clinical mastitis Staphylococcus aureus isolates from sheep flocks of the Northeast of Brazil.

    Science.gov (United States)

    de Almeida, Lara M; de Almeida, Mayra Zilta P R B; de Mendonça, Carla L; Mamizuka, Elsa M

    2013-01-01

    Staphylococcus aureus is one of the most frequent mastitis causative agents in small ruminants. The expression of most virulence genes of S. aureus is controlled by an accessory gene regulator (agr) locus. This study aimed to ascertain the prevalence of the different agr groups and to evaluate the occurrence of encoding genes for cytotoxin, adhesins and toxins with superantigen activity in S. aureus isolates from milk of ewes with clinical and subclinical mastitis in sheep flocks raised for meat production The agr groups I and II were identified in both cases of clinical and subclinical mastitis. Neither the arg groups III and IV nor negative agr were found. The presence of cflA gene was identified in 100% of the isolates. The frequency of hla and lukE-D genes was high - 77.3 and 82.8%, respectively and all isolates from clinical mastitis presented these genes. The sec gene, either associated to tst gene or not, was identified only in isolates from subclinical mastitis. None of the following genes were identified: bbp, ebpS, cna, fnbB, icaA, icaD, bap, hlg, lukM-lukF-PV and se-a-b-d-e. PMID:24294245

  5. 粪肠球菌毒力基因及耐药性分析%The Incidence of Virulence Genes and AntibioticResistence in Enterococcus Faecalis Strains

    Institute of Scientific and Technical Information of China (English)

    祝进; 白永凤; 陆军; 陈晓; 陈瑜

    2012-01-01

    Objective To examine the occurrence of known virulence factor genes in a group of E. Faecalis strains isolated from clinical isolates and healthy individuals, and to explore the relationship between the virulence genes to pathogenicity and antibiotic resistance. Methods A total of 113 E. Faecalis strains, isolated from clinical specimens (89 strains) and healthy individuals (24 strains) , were investigated for the presence of nine virulence genes including aggA, cylA, cylB, cylM, eep, efaA, enlA, espandgelE by using PCR. Antimicrobial susceptibility was determined by the K-B method among clinical isolates. Results The data showed 86. 7% of the strains carried at least one virulence marker. Most of the strains carried eep(76.1% ) ,efaA (74.3% ) ,esp(52.2% ) and aggA (52.2% ) genes respectively, whereas the remaining virulence markers were detected in variable percentages ranging from 31.9 to 47.8%. Excepting enlA, the presences of other virulence genes in clinical isolates were significantly more common than isolates from healthy individuals. The results showed most isolates (23.9% ) carried 8 kinds of virulence genes. The resistance rates of clinical isolates to CIP,P,TET were high, resistance to F/M was low, while none of strains appeared to be resistance VAN and TEC. Finally, excepting GEH, there was no significant association between number of virulence markers and antibiotic resistance. Conclusion The distribution of virulence genes among E. Faecalis is associated with the increased risk of causing clinical infection, while the relationship between virulence genes and antibiotic resistance should be further studied in detail.%目的 了解临床标本与健康人群肠道来源粪肠球菌(Enterococcus faecalis,Efa)的毒力基因分布,探讨毒力基因与细菌致病性及抗生素耐药性之间关系.方法 收集89株分离临床标本和24株健康人群的粪肠球菌,采用PCR方法检测aggA、cylA、cylB、cylM、eep、efaA、enlA、esp和gelE基

  6. Molecular cloning and characterization of cgt, the Brucella abortus cyclic beta-1,2-glucan transporter gene, and its role in virulence.

    Science.gov (United States)

    Roset, Mara S; Ciocchini, Andrés E; Ugalde, Rodolfo A; Iñón de Iannino, Nora

    2004-04-01

    The animal pathogen Brucella abortus contains a gene cgt, which complemented Sinorhizobium meliloti nodule development (ndvA) and Agrobacterium tumefaciens chromosomal virulence (chvA) mutants. Complemented strains recovered the presence of anionic cyclic beta-1,2-glucan, motility, tumor induction in A. tumefaciens, and nodule occupancy in S. meliloti, all traits strictly associated with the presence of cyclic beta-1,2-glucan in the periplasm. Nucleotide sequencing revealed that B. abortus cgt contains a 1,797-bp open reading frame coding for a predicted membrane protein of 599 amino acids (65.9 kDa) that is 58.5 and 59.9% identical to S. meliloti NdvA and A. tumefaciens ChvA, respectively. Additionally, B. abortus cgt, like S. meliloti ndvA and A. tumefaciens chvA possesses ATP-binding motifs and the ABC signature domain features of a typical ABC transporter. Characterization of Cgt was carried out by the construction of null mutants in B. abortus 2308 and S19 backgrounds. Both mutants do not transport cyclic beta-1,2-glucan to the periplasm, as shown by the absence of anionic cyclic glucan, and they display reduced virulence in mice and defective intracellular multiplication in HeLa cells. These results suggest that cyclic beta-1,2-glucan must be transported into the periplasmatic space to exert its action as a virulence factor. PMID:15039351

  7. Sulfonamide and tetracycline resistance genes in total- and culturable-bacterial assemblages in South African aquatic environments

    OpenAIRE

    Satoru eSuzuki; Mitsuko eOgo; Tatsuya eKoike; Hideshige eTakada; Brent eNewman

    2015-01-01

    Antibiotic resistant bacteria (ARB) are ubiquitous in the natural environment. The introduction of effluent derived antibiotic resistance genes (ARGs) into aquatic environments is of concern in the spreading of genetic risk. This study showed the prevalence of sulfonamide and tetracycline resistance genes, sul1, sul2, sul3 and tet(M), in the total bacterial assemblage and colony forming bacterial assemblage in river and estuarine water and sewage treatment plants (STP) in South Africa. There ...

  8. Sulfonamide and tetracycline resistance genes in total- and culturable-bacterial assemblages in South African aquatic environments

    OpenAIRE

    Suzuki, Satoru; Ogo, Mitsuko; Koike, Tatsuya; Takada, Hideshige; Newman, Brent

    2015-01-01

    Antibiotic resistant bacteria are ubiquitous in the natural environment. The introduction of effluent derived antibiotic resistance genes (ARGs) into aquatic environments is of concern in the spreading of genetic risk. This study showed the prevalence of sulfonamide and tetracycline resistance genes, sul1, sul2, sul3, and tet(M), in the total bacterial assemblage and colony forming bacterial assemblage in river and estuarine water and sewage treatment plants (STP) in South Africa. There was no ...

  9. Nature of bacterial colonization influences transcription of mucin genes in mice during the first week of life

    OpenAIRE

    Bergström Anders; Kristensen Matilde B; Bahl Martin I; Metzdorff Stine B; Fink Lisbeth N; Frøkiær Hanne; Licht Tine R

    2012-01-01

    Abstract Background Postnatal regulation of the small intestinal mucus layer is potentially important in the development of adult gut functionality. We hypothesized that the nature of bacterial colonization affects mucus gene regulation in early life. We thus analyzed the influence of the presence of a conventional microbiota as well as two selected monocolonizing bacterial strains on the transcription of murine genes involved in mucus layer development during the first week of life. Mouse pu...

  10. Disruption of Francisella tularensis Schu S4 iglI, iglJ, and pdpC genes results in attenuation for growth in human macrophages and in vivo virulence in mice and reveals a unique phenotype for pdpC.

    Science.gov (United States)

    Long, Matthew E; Lindemann, Stephen R; Rasmussen, Jed A; Jones, Bradley D; Allen, Lee-Ann H

    2013-03-01

    Francisella tularensis is a facultative intracellular bacterial pathogen and the causative agent of tularemia. After infection of macrophages, the organism escapes from its phagosome and replicates to high density in the cytosol, but the bacterial factors required for these aspects of virulence are incompletely defined. Here, we describe the isolation and characterization of Francisella tularensis subsp. tularensis strain Schu S4 mutants that lack functional iglI, iglJ, or pdpC, three genes of the Francisella pathogenicity island. Our data demonstrate that these mutants were defective for replication in primary human monocyte-derived macrophages and murine J774 cells yet exhibited two distinct phenotypes. The iglI and iglJ mutants were similar to one another, exhibited profound defects in phagosome escape and intracellular growth, and appeared to be trapped in cathepsin D-positive phagolysosomes. Conversely, the pdpC mutant avoided trafficking to lysosomes, phagosome escape was diminished but not ablated, and these organisms replicated in a small subset of infected macrophages. The phenotype of each mutant strain was reversed by trans complementation. In vivo virulence was assessed by intranasal infection of BALB/c mice. The mutants appeared avirulent, as all mice survived infection with 10(8) CFU iglJ- or pdpC-deficient bacteria. Nevertheless, the pdpC mutant disseminated to the liver and spleen before being eliminated, whereas the iglJ mutant did not. Taken together, our data demonstrate that the pathogenicity island genes tested are essential for F. tularensis Schu S4 virulence and further suggest that pdpC may play a unique role in this process, as indicated by its distinct intermediate phenotype. PMID:23275090

  11. OpWise: Operons aid the identification of differentially expressed genes in bacterial microarray experiments

    Directory of Open Access Journals (Sweden)

    Arkin Adam P

    2006-01-01

    Full Text Available Abstract Background Differentially expressed genes are typically identified by analyzing the variation between replicate measurements. These procedures implicitly assume that there are no systematic errors in the data even though several sources of systematic error are known. Results OpWise estimates the amount of systematic error in bacterial microarray data by assuming that genes in the same operon have matching expression patterns. OpWise then performs a Bayesian analysis of a linear model to estimate significance. In simulations, OpWise corrects for systematic error and is robust to deviations from its assumptions. In several bacterial data sets, significant amounts of systematic error are present, and replicate-based approaches overstate the confidence of the changers dramatically, while OpWise does not. Finally, OpWise can identify additional changers by assigning genes higher confidence if they are consistent with other genes in the same operon. Conclusion Although microarray data can contain large amounts of systematic error, operons provide an external standard and allow for reasonable estimates of significance. OpWise is available at http://microbesonline.org/OpWise.

  12. Antimicrobial activity and the presence of virulence factors and bacteriocin structural genes in Enterococcus faecium CM33 isolated from ewe colostrum

    Directory of Open Access Journals (Sweden)

    YOUSEF eNAMI

    2015-07-01

    Full Text Available AbstractScreening of lactic acid bacteria isolated from ewe colostrum led to the identification and isolation of Enterococcus faecium CM33 with interesting features, such as high-survival rates under acidic or bile salt conditions, high tolerance to the simulated gastrointestinal condition, and high adhesive potential to Caco-2 cells. According to the inhibition of pathogen adhesion test results, this strain could reduce more than 50% adhesion capacity of Escherichia coli, Shigella flexneri, Klebsiella pneumoniae, Listeria monocytogenes, and Staphylococcus aureus to Caco-2 cells. Based on the antibiotic sensitivity test findings, E. faecium CM33 was susceptible to gentamycin, vancomycin, erythromycin, ampicillin, penicillin, tetracycline, and rifampicin, but resistant to chloramphenicol, clindamycin, and kanamycin. Upon the assessment of the virulence determinants for E. faecium CM33, this strain was negative for all tested virulence genes. Furthermore, the genome of this strain was evaluated for the incidence of the known enterocin genes by specific PCR amplification, and the genes encoding enterocins A, 31, X, and Q were discovered. The findings of this study showed that the strain E. faecium CM33 could be considered a valuable nutraceutical, and it can be introduced as a new potential probiotic.

  13. Small RNA Derived from the Virulence Modulating Region of the Potato spindle tuber viroid Silences callose synthase Genes of Tomato Plants.

    Science.gov (United States)

    Adkar-Purushothama, Charith Raj; Brosseau, Chantal; Giguère, Tamara; Sano, Teruo; Moffett, Peter; Perreault, Jean-Pierre

    2015-08-01

    The tomato (Solanum lycopersicum) callose synthase genes CalS11-like and CalS12-like encode proteins that are essential for the formation of callose, a major component of pollen mother cell walls; these enzymes also function in callose formation during pathogen infection. This article describes the targeting of these callose synthase mRNAs by a small RNA derived from the virulence modulating region of two Potato spindle tuber viroid variants. More specifically, viroid infection of tomato plants resulted in the suppression of the target mRNAs up to 1.5-fold, depending on the viroid variant used and the gene targeted. The targeting of these mRNAs by RNA silencing was validated by artificial microRNA experiments in a transient expression system and by RNA ligase-mediated rapid amplification of cDNA ends. Viroid mutants incapable of targeting callose synthase mRNAs failed to induce typical infection phenotypes, whereas a chimeric viroid obtained by swapping the virulence modulating regions of a mild and a severe variant of Potato spindle tuber viroid greatly affected the accumulation of viroids and the severity of disease symptoms. These data provide evidence of the silencing of multiple genes by a single small RNA derived from a viroid. PMID:26290537

  14. Application of relative real-time PCR to detect differential expression of virulence genes in Vibrio anguillarum under standard and stressed growth conditions.

    Science.gov (United States)

    Crisafi, F; Denaro, R; Genovese, M; Yakimov, M; Genovese, L

    2014-07-01

    In this study, we aimed to understand whether abiotic factors affect the expression of virulence genes in Vibrio anguillarum. We observed the in vitro responses of two Mediterranean strains of V. anguillarum to temperature, NaCl and iron concentration changes. We monitored growth performance and gene transcription levels by comparing the results obtained under stressed conditions (temperatures of 5 °C, 15 °C and 37 °C; NaCl concentrations of 3% and 5%; and iron depletion and excess) with those obtained under standard growth conditions (25 °C, 1.5% NaCl and 0.6 μm of iron). The results showed that the strains respond differently. The strain 975/I was most strongly affected by conditions of 15 °C and iron depletion; these conditions induced increased transcription levels of empA, angR and fatA. Growth of the strain 17/I was inhibited at 15 °C and in iron depletion conditions; this strain also showed dramatic changes in the transcription levels of toxR and tonB2 under increased NaCl concentrations. These results demonstrate that environmental stress affects the expression of virulence genes in V. anguillarum that have implications for the competitiveness, stress tolerance and the ability of V. anguillarum to cause infection. PMID:24033758

  15. Small RNA Derived from the Virulence Modulating Region of the Potato spindle tuber viroid Silences callose synthase Genes of Tomato Plants[OPEN

    Science.gov (United States)

    Adkar-Purushothama, Charith Raj; Brosseau, Chantal; Giguère, Tamara; Sano, Teruo; Moffett, Peter; Perreault, Jean-Pierre

    2015-01-01

    The tomato (Solanum lycopersicum) callose synthase genes CalS11-like and CalS12-like encode proteins that are essential for the formation of callose, a major component of pollen mother cell walls; these enzymes also function in callose formation during pathogen infection. This article describes the targeting of these callose synthase mRNAs by a small RNA derived from the virulence modulating region of two Potato spindle tuber viroid variants. More specifically, viroid infection of tomato plants resulted in the suppression of the target mRNAs up to 1.5-fold, depending on the viroid variant used and the gene targeted. The targeting of these mRNAs by RNA silencing was validated by artificial microRNA experiments in a transient expression system and by RNA ligase-mediated rapid amplification of cDNA ends. Viroid mutants incapable of targeting callose synthase mRNAs failed to induc