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Sample records for virulent csfv strains

  1. Virulence in pigs of vPader10 rescued from an infectious cDNA clone of the CSFV strain Paderborn

    DEFF Research Database (Denmark)

    Friis, Martin Barfred; Nielsen, Jens; Uttenthal, Åse

    The BAC clone, pBeloPader10, contains a complete cDNA of the CSFV strain Paderborn. Virus, named vPader10, was rescued from this construct by electroporation of RNA transcripts into porcine PK15 cells. To further study the characteristics of vPader10, we evaluated the virulence of this virus...... in vivo in pigs. An animal experiment was performed where three pigs were inoculated with vPader10 and housed in-contact with two non-inoculated pigs for 5 weeks. Following inoculation with vPader10, two out of three pigs displayed severe clinical signs of CSF from PID 14 that progressed until death...... of the pigs at PID 21 and PID 22, respectively. High fever (>41ºC) was observed in these pigs from PID 14 and remained at a high level until day of death. One of two contact pigs developed similar clinical disease that initiated at PID 21 and progressed until it was euthanised at PID 32 due to severe clinical...

  2. Early pathogenesis of classical swine fever virus (CSFV) strains in Danish pigs

    DEFF Research Database (Denmark)

    Lohse, Louise; Nielsen, Jens; Uttenthal, Åse

    2012-01-01

    Host–virus interactions play an important role for the clinical outcome of classicalswinefevervirus (CSFV) infections in pigs. Strain virulence, host characteristics and environment are all factors that markedly influence disease severity. We tested CSFV strains of varying virulence...... in an experimental set-up, reducing the influence of host and environmental factors. Thus, weaner pigs were inoculated with one of 4 CSFV strains in order to compare the pathogenesis for a 3-week-period after infection. CSFV strains selected were 2 new and 2 previously characterized. None of these strains had been...... tested in Danish outbred pigs before. Clinical observations grouped the infected pigs into two different categories reflecting either non-specific, mainly gastro-intestinal, problems, or severe disease including high fever within the first week after inoculation. Gross-pathological findings varied...

  3. A comparison of early pathogenesis of CSFV-Glentorf and CSFV-Romania in Danish pigs

    DEFF Research Database (Denmark)

    Lohse, Louise; Uttenthal, Åse; Nielsen, Jens

    forms. Crucial factors for the clinical outcome of infection include strain virulence and host characteristics such as pig age, microbial health status and genetic background. In the presented experimental animal study, we inoculated young conventional Danish pigs with two different strains of CSFV: One...... effect on these two groups, and clinical symptoms resolved after 1-2 days of therapy. For the Romania-infected pigs, CS increased throughout the experiment from PID6 with mean CS=3 until termination of the experiment with mean CS=19 at PID18. Clinical symptoms in this group were dominated by diarrhea......, lethargy, changed body shape, coordination problems and further on respiratory symptoms and ataxia. Antibiotic therapy had no effect in this group. Virus distribution: Control pigs were all negative by RT-PCR analysis for CSFV. In Glentorf-infected pigs, CSFV RNA was found in blood samples of 6/10 pigs...

  4. Development of a new LAMP assay for the detection of CSFV strains from Cuba: a proof-of-concept study.

    Science.gov (United States)

    Postel, Alexander; Pérez, Lester J; Perera, Carmen L; Schmeiser, Stefanie; Meyer, Denise; Meindl-Boehmer, Alexandra; Rios, Liliam; Austermann-Busch, Sophia; Frias-Lepoureau, Maria T; Becher, Paul

    2015-06-01

    Classical swine fever (CSF) is a devastating animal disease of great economic impact worldwide. In many countries, CSF has been endemic for decades, and vaccination of domestic pigs is one of the measures to control the disease. Consequently, differentiating infected from vaccinated animals by antibody ELISA screening is not applicable. In some countries, such as Cuba, lack of molecular techniques for sensitive, rapid and reliable detection of virus genomes is a critical point. To overcome this problem, an easy-to-use one-tube assay based on the loop-mediated isothermal amplification (LAMP) principle has been developed for detection of the genome of CSF virus (CSFV) of endemic Cuban genotype 1.4 isolates. The assay reliably detected recent isolates from three different regions of Cuba with an analytical sensitivity 10-100 times lower than that of quantitative reverse transcription RT-qPCR. Diagnostic test sensitivity was examined using reference sera from two groups of pigs experimentally infected with Cuban virulent strain CSF0705 "Margarita" and the recent field isolate CSF1058 "Pinar del Rio". Differences in pathogenicity of the two viruses were reflected in the clinical course of disease as well as in virus loads of blood samples. Low viral RNA loads in samples from pigs infected with the field isolate caused serious detection problems in RT-LAMP as well as in RT-qPCR. Thus, it will be necessary in future research to focus on targeted sampling of diseased animals and to restrict diagnosis to the herd level in order to establish LAMP as an efficient tool for diagnosing CSF under field conditions.

  5. Rescue of the highly virulent classical swine fever virus strain “Koslov” from cloned cDNA and first insights into genome variations relevant for virulence

    DEFF Research Database (Denmark)

    Fahnøe, Ulrik; Pedersen, Anders Gorm; Risager, Peter Christian

    2014-01-01

    Classical swine fever virus (CSFV) strain “Koslov” is highly virulent with a mortality rate of up to 100% in pigs. In this study, we modified non-functional cDNAs generated from the blood of Koslov virus infected pigs bysite-directed mutagenesis, removing non-synonymous mutations step-by-step, th......Classical swine fever virus (CSFV) strain “Koslov” is highly virulent with a mortality rate of up to 100% in pigs. In this study, we modified non-functional cDNAs generated from the blood of Koslov virus infected pigs bysite-directed mutagenesis, removing non-synonymous mutations step......-by-step, thereby producing genomes encoding the consensus amino acid sequence. Viruses rescued from the construct corresponding to the inferred parental form were highly virulent, when tested in pigs, with infected animals displaying pronounced clinical symptoms leading to high mortality. The reconstruction...

  6. Recoding structural glycoprotein E2 in classical swine fever virus (CSFV) produces complete virus attenuation in swine and protects infected animals against disease.

    Science.gov (United States)

    Velazquez-Salinas, Lauro; Risatti, Guillermo R; Holinka, Lauren G; O'Donnell, Vivian; Carlson, Jolene; Alfano, Marialexia; Rodriguez, Luis L; Carrillo, Consuelo; Gladue, Douglas P; Borca, Manuel V

    2016-07-01

    Controlling classical swine fever (CSF) mainly involves vaccination with live attenuated vaccines (LAV). Experimental CSFV LAVs has been lately developed through reverse genetics using several different approaches. Here we present that codon de-optimization in the major CSFV structural glycoprotein E2 coding region, causes virus attenuation in swine. Four different mutated constructs (pCSFm1-pCSFm4) were designed using various mutational approaches based on the genetic background of the highly virulent strain Brescia (BICv). Three of these constructs produced infectious viruses (CSFm2v, CSFm3v, and CSFm4v). Animals infected with CSFm2v presented a reduced and extended viremia but did not display any CSF-related clinical signs. Animals that were infected with CSFm2v were protected against challenge with virulent parental BICv. This is the first report describing the development of an attenuated CSFV experimental vaccine by codon usage de-optimization, and one of the few examples of virus attenuation using this methodology that is assessed in a natural host. Published by Elsevier Inc.

  7. 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.

  8. Identification of Secreted Exoproteome Fingerprints of Highly-Virulent and Non-Virulent Staphylococcus aureus Strains.

    Science.gov (United States)

    Bonar, Emilia; Wojcik, Iwona; Jankowska, Urszula; Kedracka-Krok, Sylwia; Bukowski, Michal; Polakowska, Klaudia; Lis, Marcin W; Kosecka-Strojek, Maja; Sabat, Artur J; Dubin, Grzegorz; Friedrich, Alexander W; Miedzobrodzki, Jacek; Dubin, Adam; Wladyka, Benedykt

    2016-01-01

    Staphylococcus aureus is a commensal inhabitant of skin and mucous membranes in nose vestibule but also an important opportunistic pathogen of humans and livestock. The extracellular proteome as a whole constitutes its major virulence determinant; however, the involvement of particular proteins is still relatively poorly understood. In this study, we compared the extracellular proteomes of poultry-derived S. aureus strains exhibiting a virulent (VIR) and non-virulent (NVIR) phenotype in a chicken embryo experimental infection model with the aim to identify proteomic signatures associated with the particular phenotypes. Despite significant heterogeneity within the analyzed proteomes, we identified alpha-haemolysin and bifunctional autolysin as indicators of virulence, whereas glutamylendopeptidase production was characteristic for non-virulent strains. Staphopain C (StpC) was identified in both the VIR and NVIR proteomes and the latter fact contradicted previous findings suggesting its involvement in virulence. By supplementing NVIR, StpC-negative strains with StpC, and comparing the virulence of parental and supplemented strains, we demonstrated that staphopain C alone does not affect staphylococcal virulence in a chicken embryo model.

  9. CSFV proliferation is associated with GBF1 and Rab2

    Indian Academy of Sciences (India)

    Fulltext. Click here to view fulltext PDF. Permanent link: ... after BFA and GCA treatment. CSFV multiplication dynamics were retarded in cells transfected withGBF1 and Rab2 shRNA. ... Hence, Golgi function is important for CSFV multiplication, and GBF1 and Rab2 participate inCSFV proliferation. Further studies must ...

  10. Virulence parameters in the characterization of strains of Entamoeba histolytica

    Directory of Open Access Journals (Sweden)

    Maria A GOMES

    1997-03-01

    Full Text Available Differences in virulence of strains of Entamoeba histolytica have long been detected by various experimental assays, both in vivo and in vitro. Discrepancies in the strains characterization have been arisen when different biological assays are compared. In order to evaluate different parameters of virulence in the strains characterization, five strains of E. histolytica, kept under axenic culture, were characterized in respect to their, capability to induce hamster liver abscess, erythrophagocytosis rate and cytopathic effect upon VERO cells. It was found significant correlation between in vitro biological assays, but not between in vivo and in vitro assays. Good correlation was found between cytopathic effect and the mean number of uptaken erythrocytes, but not with percentage of phagocytic amoebae, showing that great variability can be observed in the same assay, according to the variable chosen. It was not possible to correlate isoenzyme and restriction fragment pattern with virulence indexes since all studied strains presented pathogenic patterns. The discordant results observed in different virulence assays suggests that virulence itself may not the directly assessed. What is in fact assessed are different biological characteristics or functions of the parasite more than virulence itself. These characteristics or functions may be related or not with pathogenic mechanisms occurring in the development of invasive amoebic diseaseParâmetros de virulência na caracterização de Cepas de Entamoeba histolytica. A caracterização quanto a virulência das diferentes cepas de E. histolytica foi avaliada através de ensaios in vivo e in vitro. Discrepâncias nesta caracterização têm surgido quando se compara os diferentes ensaios. Avaliamos alguns parâmetros de virulência na caracterização de 5 cepas axênicas de E. histolytica. Estas cepas foram caracterizadas com relação à sua capacidade para induzir abscesso em fígado de hamster

  11. Competition between two virulent Marek's disease virus strains in vivo.

    Science.gov (United States)

    Dunn, John R; Silva, Robert F; Lee, Lucy F; Witter, Richard L

    2012-01-01

    Previous studies have demonstrated the presence of multiple strains of Marek's disease virus simultaneously circulating within poultry flocks, leading to the assumption that individual birds are repeatedly exposed to a variety of virus strains in their lifetime. Virus competition within individual birds may be an important factor that influences the outcome of co-infection under field conditions, including the potential outcome of emergence or evolution of more virulent strains. A series of experiments was designed to evaluate virus competition within chickens following simultaneous challenge with two virulent serotype 1 Marek's disease virus strains, using either pathogenically similar (rMd5 and rMd5/pp38CVI) or dissimilar (JM/102W and rMd5/pp38CVI) virus pairs. Bursa of Fabricius, feather follicle epithelium, spleen, and tumour samples were collected at multiple time points to determine the frequency and distribution of each virus present using pyrosequencing, immunohistochemistry and virus isolation. In the similar pair, rMd5 appeared to have a competitive advantage over rMd5/pp38CVI, which in turn had a competitive advantage over the less virulent JM/102W in the dissimilar virus pair. Dominance of one strain over the other was not absolute for either virus pair, as the subordinate virus was rarely eliminated. Interestingly, competition between two viruses with either pair rarely ended in a draw. Further work is needed to identify factors that influence virus-specific dominance to better understand what characteristics favour emergence of one strain in chicken populations at the expense of other strains.

  12. Genetic Variation in Virulence among Chalkbrood Strains Infecting Honeybees

    Science.gov (United States)

    Vojvodic, Svjetlana; Jensen, Annette B.; Markussen, Bo; Eilenberg, Jørgen; Boomsma, Jacobus J.

    2011-01-01

    Ascosphaera apis causes chalkbrood in honeybees, a chronic disease that reduces the number of viable offspring in the nest. Although lethal for larvae, the disease normally has relatively low virulence at the colony level. A recent study showed that there is genetic variation for host susceptibility, but whether Ascosphaera apis strains differ in virulence is unknown. We exploited a recently modified in vitro rearing technique to infect honeybee larvae from three colonies with naturally mated queens under strictly controlled laboratory conditions, using four strains from two distinct A. apis clades. We found that both strain and colony of larval origin affected mortality rates. The strains from one clade caused 12–14% mortality while those from the other clade induced 71–92% mortality. Larvae from one colony showed significantly higher susceptibility to chalkbrood infection than larvae from the other two colonies, confirming the existence of genetic variation in susceptibility across colonies. Our results are consistent with antagonistic coevolution between a specialized fungal pathogen and its host, and suggest that beekeeping industries would benefit from more systematic monitoring of this chronic stress factor of their colonies. PMID:21966406

  13. Genetic variation in virulence among chalkbrood strains infecting honeybees.

    Directory of Open Access Journals (Sweden)

    Svjetlana Vojvodic

    Full Text Available Ascosphaera apis causes chalkbrood in honeybees, a chronic disease that reduces the number of viable offspring in the nest. Although lethal for larvae, the disease normally has relatively low virulence at the colony level. A recent study showed that there is genetic variation for host susceptibility, but whether Ascosphaera apis strains differ in virulence is unknown. We exploited a recently modified in vitro rearing technique to infect honeybee larvae from three colonies with naturally mated queens under strictly controlled laboratory conditions, using four strains from two distinct A. apis clades. We found that both strain and colony of larval origin affected mortality rates. The strains from one clade caused 12-14% mortality while those from the other clade induced 71-92% mortality. Larvae from one colony showed significantly higher susceptibility to chalkbrood infection than larvae from the other two colonies, confirming the existence of genetic variation in susceptibility across colonies. Our results are consistent with antagonistic coevolution between a specialized fungal pathogen and its host, and suggest that beekeeping industries would benefit from more systematic monitoring of this chronic stress factor of their colonies.

  14. Hereditary Hemochromatosis Restores the Virulence of Plague Vaccine Strains

    Science.gov (United States)

    Quenee, Lauriane E.; Hermanas, Timothy M.; Ciletti, Nancy; Louvel, Helene; Miller, Nathan C.; Elli, Derek; Blaylock, Bill; Mitchell, Anthony; Schroeder, Jay; Krausz, Thomas; Kanabrocki, Joseph; Schneewind, Olaf

    2012-01-01

    Nonpigmented Yersinia pestis (pgm) strains are defective in scavenging host iron and have been used in live-attenuated vaccines to combat plague epidemics. Recently, a Y. pestis pgm strain was isolated from a researcher with hereditary hemochromatosis who died from laboratory-acquired plague. We used hemojuvelin-knockout (Hjv−/−) mice to examine whether iron-storage disease restores the virulence defects of nonpigmented Y. pestis. Unlike wild-type mice, Hjv−/− mice developed lethal plague when challenged with Y. pestis pgm strains. Immunization of Hjv−/− mice with a subunit vaccine that blocks Y. pestis type III secretion generated protection against plague. Thus, individuals with hereditary hemochromatosis may be protected with subunit vaccines but should not be exposed to live-attenuated plague vaccines. PMID:22896664

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

    Science.gov (United States)

    Rhoades, K R; Rimler, R B

    1993-01-01

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

  16. Galleria mellonella model identifies highly virulent strains among all major molecular types of Cryptococcus gattii.

    Directory of Open Access Journals (Sweden)

    Carolina Firacative

    Full Text Available Cryptococcosis is mainly caused by Cryptococcus neoformans. However, the number of cases due to C. gattii is increasing, affecting mainly immunocompetent hosts. C. gattii is divided into four major molecular types, VGI to VGIV, which differ in their host range, epidemiology, antifungal susceptibility and geographic distribution. Besides studies on the Vancouver Island outbreak strains, which showed that the subtype VGIIa is highly virulent compared to the subtype VGIIb, little is known about the virulence of the other major molecular types. To elucidate the virulence potential of the major molecular types of C. gattii, Galleria mellonella larvae were inoculated with ten globally selected strains per molecular type. Survival rates were recorded and known virulence factors were studied. One VGII, one VGIII and one VGIV strain were more virulent (p 0.05, 21 (five VGI, five VGII, four VGIII and seven VGIV were less virulent (p <0.05 while one strain of each molecular type were avirulent. Cell and capsule size of all strains increased markedly during larvae infection (p <0.001. No differences in growth rate at 37°C were observed. Melanin synthesis was directly related with the level of virulence: more virulent strains produced more melanin than less virulent strains (p <0.05. The results indicate that all C. gattii major molecular types exhibit a range of virulence, with some strains having the potential to be more virulent. The study highlights the necessity to further investigate the genetic background of more and less virulent strains in order to recognize critical features, other than the known virulence factors (capsule, melanin and growth at mammalian body temperature, that maybe crucial for the development and progression of cryptococcosis.

  17. Presence of virulent strains of amphizoic amoebae in swimming pools of the city of Szczecin

    National Research Council Canada - National Science Library

    Górnik, Katarzyna; Kuźna-Grygiel, Wanda

    2004-01-01

    .... No pathogenic strains were detected in the water sampled in the indoor swimming pools, and the virulent strains, AD 16, AD 148, AD 166, AM 17, and AM 148, were found only in the open-air swimming pools...

  18. Phenotypic and Genotypic Characterization of Virulent Yersinia enterocolitica Strains Unable To Ferment Sucrose

    Science.gov (United States)

    Guiyoule, Annie; Guinet, Françoise; Martin, Liliane; Benoit, Catherine; Desplaces, Nicole; Carniel, Elisabeth

    1998-01-01

    Several atypical sucrose-negative Yersinia strains, isolated from clinical samples and sometimes associated with symptoms, proved to have full virulence potential in in vitro and in vivo testings. DNA-relatedness studies revealed that they were authentic Yersinia enterocolitica strains. Therefore, atypical sucrose-negative Yersinia isolates should be analyzed for their virulence potential. PMID:9705424

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

    Science.gov (United States)

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

    2017-02-01

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

  20. 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.

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

    Science.gov (United States)

    Demir, Feyza; Kuştimur, Semra

    2014-10-01

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

  2. A wide extent of inter-strain diversity in virulent and vaccine strains of alphaherpesviruses.

    Directory of Open Access Journals (Sweden)

    Moriah L Szpara

    2011-10-01

    Full Text Available Alphaherpesviruses are widespread in the human population, and include herpes simplex virus 1 (HSV-1 and 2, and varicella zoster virus (VZV. These viral pathogens cause epithelial lesions, and then infect the nervous system to cause lifelong latency, reactivation, and spread. A related veterinary herpesvirus, pseudorabies (PRV, causes similar disease in livestock that result in significant economic losses. Vaccines developed for VZV and PRV serve as useful models for the development of an HSV-1 vaccine. We present full genome sequence comparisons of the PRV vaccine strain Bartha, and two virulent PRV isolates, Kaplan and Becker. These genome sequences were determined by high-throughput sequencing and assembly, and present new insights into the attenuation of a mammalian alphaherpesvirus vaccine strain. We find many previously unknown coding differences between PRV Bartha and the virulent strains, including changes to the fusion proteins gH and gB, and over forty other viral proteins. Inter-strain variation in PRV protein sequences is much closer to levels previously observed for HSV-1 than for the highly stable VZV proteome. Almost 20% of the PRV genome contains tandem short sequence repeats (SSRs, a class of nucleic acids motifs whose length-variation has been associated with changes in DNA binding site efficiency, transcriptional regulation, and protein interactions. We find SSRs throughout the herpesvirus family, and provide the first global characterization of SSRs in viruses, both within and between strains. We find SSR length variation between different isolates of PRV and HSV-1, which may provide a new mechanism for phenotypic variation between strains. Finally, we detected a small number of polymorphic bases within each plaque-purified PRV strain, and we characterize the effect of passage and plaque-purification on these polymorphisms. These data add to growing evidence that even plaque-purified stocks of stable DNA viruses exhibit

  3. Recombinant Encephalomyocarditis Viruses Elicit Neutralizing Antibodies against PRRSV and CSFV in Mice.

    Science.gov (United States)

    Zhu, Shu; Guo, Xin; Keyes, Lisa R; Yang, Hanchun; Ge, Xinna

    2015-01-01

    Encephalomyocarditis virus (EMCV) is capable of infecting a wide range of species and the infection can cause myocarditis and reproductive failure in pigs as well as febrile illness in human beings. In this study, we introduced the entire ORF5 of the porcine reproductive and respiratory syndrome virus (PRRSV) or the neutralization epitope regions in the E2 gene of the classical swine fever virus (CSFV), into the genome of a stably attenuated EMCV strain, T1100I. The resultant viable recombinant viruses, CvBJC3m/I-ΔGP5 and CvBJC3m/I-E2, respectively expressed partial PRRSV envelope protein GP5 or CSFV neutralization epitope A1A2 along with EMCV proteins. These heterologous proteins fused to the N-terminal of the nonstructural leader protein could be recognized by anti-GP5 or anti-E2 antibody. We also tested the immunogenicity of these fusion proteins by immunizing BALB/c mice with the recombinant viruses. The immunized animals elicited neutralizing antibodies against PRRSV and CSFV. Our results suggest that EMCV can be engineered as an expression vector and serve as a tool in the development of novel live vaccines in various animal species.

  4. On the analysis of the virulence nature of TIGR4 and R6 strains of ...

    Indian Academy of Sciences (India)

    ... such as pneumoniae, bacteremia, meningitis, etc. After the whole genome of two strains of S. pneumoniae, the virulent TIGR4 and non-pathogenic R6 were sequenced; there is a hope that comparing the genomes will allow an identification of the genes responsible for its virulence and thus the development of treatment ...

  5. Exposure to pairs of Aeromonas strains enhances virulence in the Caenorhabditis elegans infection model

    Science.gov (United States)

    Aeromonad virulence remains poorly understood, and is difficult to predict from strain characteristics. In addition, infections are often polymicrobial (i.e., are mixed infections), and 5 -10% of such infections include two distinct aeromonads, which has an unknown impact on virulence. In this work,...

  6. A robust PCR for the differentiation of potential virulent strains of Haemophilus parasuis.

    Science.gov (United States)

    Galofré-Milà, N; Correa-Fiz, F; Lacouture, S; Gottschalk, M; Strutzberg-Minder, K; Bensaid, A; Pina-Pedrero, S; Aragon, V

    2017-05-08

    Haemophilus parasuis is the etiological agent of Glässer's disease in swine. H. parasuis comprises strains with heterogeneous virulence capacity, from non-virulent to highly virulent. Determination of the pathogenic potential of the strains is important for diagnosis and disease control. The virulence-associated trimeric autotransporters (vtaA) genes have been used to predict H. parasuis virulence by PCR amplification of their translocator domains. Here, we report a new and improved PCR designed to detect a different domain of the vtaA genes, the leader sequence (LS) as a diagnostic tool to predict virulence. A collection of 360 H. parasuis strains was tested by PCR with LS specific primers. Results of the PCR were compared with the clinical origin of the strains and, for a subset of strains, with their phagocytosis and serum resistance using a Chi-square test. LS-PCR was specific to H. parasuis, and allowed the differential detection of the leader sequences found in clinical and non-clinical isolates. Significant correlation was observed between the results of the LS-PCR and the clinical origin (organ of isolation) of the strains, as well as with their phagocytosis and serum susceptibility, indicating that this PCR is a good predictor of the virulence of the strains. In addition, this new PCR showed a full correlation with the previously validated PCR based on the translocator domain. LS-PCR could be performed in a wide range of annealing temperatures without losing specificity. This newly described PCR based on the leader sequence of the vtaA genes, LS-PCR, is a robust test for the prediction of the virulence potential of H. parasuis strains.

  7. Minor epidemiological importance of CSFV in “porcine high fever syndrome”

    DEFF Research Database (Denmark)

    Gaoming, Lou; Rasmussen, Thomas Bruun; Uttenthal, Åse

    The “porcine high fever syndrome (PHFS)” causing severe losses in China has been associated with several agents such as PCV-2, PRRS, APP and streptococcus. The aim of this study was to analyze the importance of CSFV in pigs in PHFS cases in China. Samples originating from 8 farms (733 Sera and 47....... As vaccination is compulsory in China, more than 95% of all pigs have antibodies and serosurveillance cannot be used. Therefore, the method for detection of CSFV in China was an IDEXX antigen ELISA analyzing full blood; based on this kit the majority of the farms were diagnosed with CSFV. Further CSFV analysis...... was performed in Denmark and CSFV was confirmed in samples from one herd only indicating a very low specificity of the previously used IDEXX antigen kit. The herd that was found CSFV positive did not use prophylactic vaccination against CSFV. In spite of the many similarities in the clinical picture of CSFV...

  8. Variable Virulence and Efficacy of BCG Vaccine Strains in Mice and Correlation With Genome Polymorphisms

    Science.gov (United States)

    Zhang, Lu; Ru, Huan-wei; Chen, Fu-zeng; Jin, Chun-yan; Sun, Rui-feng; Fan, Xiao-yong; Guo, Ming; Mai, Jun-tao; Xu, Wen-xi; Lin, Qing-xia; Liu, Jun

    2016-01-01

    Bacille Calmette–Guérin (BCG), an attenuated strain of Mycobacterium bovis, is the only vaccine available for tuberculosis (TB) control. However, BCG is not an ideal vaccine and has two major limitations: BCG exhibits highly variable effectiveness against the development of TB both in pediatric and adult populations and can cause disseminated BCG disease in immunocompromised individuals. BCG comprises a number of substrains that are genetically distinct. Whether and how these genetic differences affect BCG efficacy remains largely unknown. In this study, we performed comparative analyses of the virulence and efficacy of 13 BCG strains, representing different genetic lineages, in SCID and BALB/c mice. Our results show that BCG strains of the DU2 group IV (BCG-Phipps, BCG-Frappier, BCG-Pasteur, and BCG-Tice) exhibit the highest levels of virulence, and BCG strains of the DU2 group II (BCG-Sweden, BCG-Birkhaug) are among the least virulent group. These distinct levels of virulence may be explained by strain-specific duplications and deletions of genomic DNA. There appears to be a general trend that more virulent BCG strains are also more effective in protection against Mycobacterium tuberculosis challenge. Our findings have important implications for current BCG vaccine programs and for future TB vaccine development. PMID:26643797

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

    OpenAIRE

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

    2006-01-01

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

  10. Identification of Secreted Exoproteome Fingerprints of Highly-Virulent and Non-Virulent Staphylococcus aureus Strains

    NARCIS (Netherlands)

    Bonar, Emilia; Wojcik, Iwona; Jankowska, Urszula; Kedracka-Krok, Sylwia; Bukowski, Michal; Polakowska, Klaudia; Lis, Marcin W; Kosecka-Strojek, Maja; Sabat, Artur J; Dubin, Grzegorz; Friedrich, Alexander W; Miedzobrodzki, Jacek; Dubin, Adam; Wladyka, Benedykt

    2016-01-01

    Staphylococcus aureus is a commensal inhabitant of skin and mucous membranes in nose vestibule but also an important opportunistic pathogen of humans and livestock. The extracellular proteome as a whole constitutes its major virulence determinant; however, the involvement of particular proteins is

  11. Virulence of serotype M3 Group A Streptococcus strains in wax worms (Galleria mellonella larvae)

    Science.gov (United States)

    Watkins, M Ebru; Cantu, Concepcion C; Beres, Stephen B; Musser, James M

    2011-01-01

    Group A Streptococcus (GAS) causes human infections that range in severity from pharyngitis (“strep-throat”) to necrotizing fasciitis (“flesh-eating disease”). To facilitate investigation of the molecular basis of host-pathogen interactions, infection models capable of rapidly screening for differences in GAS strain virulence are needed. To this end, we developed a Galleria mellonella larvae (wax worm) model of invasive GAS infection and used it to compare the virulence of serotype M3 GAS strains. We found that GAS causes severe tissue damage and kills wax worms in a dose-dependent manner. The virulence of genetically distinct GAS strains was compared by Kaplan-Meier survival analysis and determining 50% lethal doses (LD50). Host-pathogen interactions were further characterized using quantitative culture, histopathology and TaqMan assays. GAS strains known to be highly pathogenic in mice and monkeys caused significantly lower survival and had significantly lower LD50s in wax worms than GAS strains associated with attenuated virulence or asymptomatic carriage. Furthermore, isogenic inactivation of proven virulence factors resulted in a significantly increased LD50 and decreased lesion size compared to the wild-type strain, a finding that also strongly correlates with animal studies. Importantly, survival analysis and LD50 determination in wax worms supported our hypothesis that a newly emerged GAS subclone that is epidemiologically associated with more human necrotizing fasciitis cases than its progenitor lineage has significantly increased virulence. We conclude that GAS virulence in wax worms strongly correlates with the data obtained in vertebrate models, and thus, the Galleria mellonella larva is a useful host organism to study GAS pathogenesis. PMID:21258213

  12. Genome-Wide Association Studies of Virulent and Avirulent Haemophilus parasuis Serotype 4 Strains.

    Science.gov (United States)

    Lawrence, Paulraj K; Wiener, Brittanny L; Kolander-Bremer, Tammy; Bey, Russell F; Stine, Douglas L; Kittichotirat, Weerayuth; Bumgarner, Roger E

    2014-09-04

    Haemophilus parasuis is a normal commensal of the upper respiratory tract of healthy pigs. However, in conjunction with stress and/or viral infections, or in immunocompromised animals, H. parasuis can transform into a pathogen causing Glasser's disease, which is typically characterized by fibrinous polyserositis, polyarthritis, meningitis, and sometimes acute pneumonia and septicemia. H. parasuis serotype 5 is highly virulent and more frequently isolated from respiratory and systemic infection in pigs. Recently Newport Laboratories isolated highly virulent H. parasuis serotype 4 strains from the tissues of diseased pigs. This study was undertaken to identify the genes responsible for H. parasuis serotype 4 virulence. To achieve this objective we performed genome-wide association studies (GWAS) across two virulent and three avirulent H. parasuis serotype 4 strains. Copyright © 2014 Lawrence et al.

  13. Genome sequencing and analysis of a highly virulent Vibrio parahaemolyticus strain isolated from the marine environment

    Science.gov (United States)

    Parks, M. C.; Moreno, E.

    2016-02-01

    Vibrio parahaemolyticus [Vp] is a Gram-negative bacterium and a natural inhabitant of coastal marine ecosystems worldwide. Vp is also a coincidental pathogen of humans. Virulent strains are commonly identified by the presence of the thermostable direct (tdh) or tdh-related (trh) hemolysin genes. However, virulence is multifaceted and many clinical Vp isolates do not carry tdh or trh. In this study, we sequenced and assembled the draft genome of a tdh- and trh-negative environmental isolate (805) shown previously to be highly virulent in zebrafish. To investigate potential mechanisms of virulence, we compared 805 to the clinical V. parahaemolyticus type strain (RIMD2210633). Pairwise comparison revealed the presence of multiple genomic regions including an IncF conjugative pilus (1.3 Kb) and a colicin V plasmid (1.49 Kb). These features are homologous to genomic regions present in clinical V. vulnificus and V. cholerae strains. Genome comparison also revealed the presence of five toxin-antitoxin systems. Isolate 805 likely attained these new features through the lateral acquisition of mobile genomic material - a hypothesis supported by the aberrant GC content of these regions. Colicin V plasmids are a diverse group of IncF plasmids found in invasive bacterial strains. Similarly, an abundance of toxin-antitoxin systems have been linked to virulence in Gram-negative bacteria. Current efforts are focused on characterizing 142 coding features present in 805 but absent from the type strain.

  14. Uropathogenic Escherichia coli (UPEC) strains may carry virulence properties of diarrhoeagenic E. coli.

    Science.gov (United States)

    Abe, Cecilia M; Salvador, Fábia A; Falsetti, Ivan N; Vieira, Mônica A M; Blanco, Jorge; Blanco, Jesús E; Blanco, Miguel; Machado, Antônia M O; Elias, Waldir P; Hernandes, Rodrigo T; Gomes, Tânia A T

    2008-04-01

    To analyze whether Escherichia coli strains that cause urinary tract infections (UPEC) share virulence characteristics with the diarrheagenic E. coli (DEC) pathotypes and to recognize their genetic diversity, 225 UPEC strains were examined for the presence of various properties of DEC and UPEC (type of interaction with HeLa cells, serogroups and presence of 30 virulence genes). No correlation between adherence patterns and serogroups was observed. Forty-five serogroups were found, but 64% of the strains belonged to one of the 12 serogroups (O1, O2, O4, O6, O7, O14, O15, O18, O21, O25, O75, and O175) and carried UPEC virulence genes (pap, hly, aer, sfa, cnf). The DEC genes found were: aap, aatA, aggC, agg3C, aggR, astA, eae, ehly, iha, irp2, lpfA(O113), pet, pic, pilS, and shf. Sixteen strains presented aggregative adherence and/or the aatA sequence, which are characteristics of enteroaggregative E. coli (EAEC), one of the DEC pathotypes. In summary, certain UPEC strains may carry DEC virulence properties, mostly associated to the EAEC pathotype. This finding raises the possibility that at least some faecal EAEC strains might represent potential uropathogens. Alternatively, certain UPEC strains may have acquired EAEC properties, becoming a potential cause of diarrhoea.

  15. Comparison of virulence-associated traits between a UPEC strain HEC4 and a APEC strain E058.

    Science.gov (United States)

    Huan, Hai-Xia; Zhou, Qiong; Zhao, Li-Xiang; Gao, Song; Liu, Xiu-Fan

    2007-10-01

    Since avian pathogenic Escherichia coli (APEC) and human uropathogenic Escherichia coli (UPEC) may encounter similar challenges when establishing infection in the extra-intestinal locations of the hosts, they may share a similar content of virulence genes and capacity to cause disease. One APEC and one UPEC isolates were compared by their content of virulence genes and other traits. The two strains showed overlap in terms of their virulence genotypes, including their possession of certain genes associated with a large transmissible plasmid of APEC, and also shared some biochemical activities. Study of the pathogenicity of UPEC in chicks showed the similar symptoms and lesions compare to those caused by APEC. Based on these results, the potential whether APEC might serve as a reservoir of plasmid-linked and virulence genes for UPEC should be considered.

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

    Directory of Open Access Journals (Sweden)

    A.W. Medeiros

    2014-01-01

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

  17. Gene expression patterns and dynamics of the colonization of common bean (Phaseolus vulgaris L. by highly virulent and weakly virulent strains of Fusarium oxysporum

    Directory of Open Access Journals (Sweden)

    Jonathan eNiño-Sánchez

    2015-04-01

    Full Text Available The dynamics of root and hypocotyl colonization, and the gene expression patterns of several fungal virulence factors and plant defense factors have been analyzed and compared in the interaction of two F. oxysporum f. sp. phaseoli strains displaying clear differences in virulence, with a susceptible common bean cultivar. The growth of the two strains on the root surface and the colonization of the root was cuantitatively similar although the highly virulent strain was more efficient reaching the central root cylinder. The main differences between both strains were found in the temporal and spatial dynamics of crown root and hypocotyl colonization. The increase of fungal biomass in the crown root was considerably larger for the highly virulent strain, which, after an initial stage of global colonization of both the vascular cylinder and the parenchymal cells, restricted its growth to the newly differentiated xylem vessels. The weakly virulent strain was a much slower and less efficient colonizer of the xylem vessels, showing also growth in the intercellular spaces of the parenchyma. Most of the virulence genes analyzed showed similar expression patterns in both strains, except SIX1, SIX6 and the gene encoding the transcription factor FTF1, which were highly upregulated in root crown and hypocotyl. The response induced in the infected plant showed interesting differences for both strains. The weakly virulent strain induced an early and strong transcription of the PR1 gene, involved in SAR response, while the highly virulent strain preferentially induced the early expression of the ethylene responsive factor ERF2.

  18. Virulence genes of Escherichia coli strains isolated from mastitic milk.

    Science.gov (United States)

    Bean, A; Williamson, J; Cursons, R T

    2004-08-01

    Escherichia coli, a Gram-negative environmental pathogen associated with bovine mastitis was isolated from the milk of 34 symptomatic cows that had been diagnosed with clinical mastitis. Eighty isolates were obtained over a 17-month period and these isolates were screened by DNA amplification for the following E. coli virulence genes: cnf1, cnf2, eaeA, eagg, einv, ltx1, stx1, stx2 and vt2e. Thirty of the bacterial isolates, obtained from 23 different cows, had toxin genes identified in their DNA. The most common virulence gene detected was stx1, with a prevalence of 31%, followed by cnf2 (7.5%), vt2e (6.25%) and eaeA (4%). The possession of different virulence genes by the bacterial isolates had no discernable impact on the health status of the cows as there was no correlation between the potential for toxin production by the E. coli isolates and the systemic clinical condition of the respective infected cows.

  19. 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.

  20. Detection of virulence genes in environmental strains of Vibrio cholerae from estuaries in northeastern Brazil.

    Science.gov (United States)

    Menezes, Francisca Gleire Rodrigues de; Neves, Soraya da Silva; Sousa, Oscarina Viana de; Vila-Nova, Candida Machado Vieira Maia; Maggioni, Rodrigo; Theophilo, Grace Nazareth Diogo; Hofer, Ernesto; Vieira, Regine Helena Silva dos Fernandes

    2014-01-01

    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.

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

    Science.gov (United States)

    de Menezes, Francisca Gleire Rodrigues; Neves, Soraya da Silva; de Sousa, Oscarina Viana; Vila-Nova, Candida Machado Vieira Maia; Maggioni, Rodrigo; Theophilo, Grace Nazareth Diogo; Hofer, Ernesto; Vieira, Regine Helena Silva dos Fernandes

    2014-01-01

    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. PMID:25229224

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

    Science.gov (United States)

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

    2016-09-20

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

  3. Pseudomonas aeruginosa ATCC 9027 is a non-virulent strain suitable for mono-rhamnolipids production.

    Science.gov (United States)

    Grosso-Becerra, María-Victoria; González-Valdez, Abigail; Granados-Martínez, María-Jessica; Morales, Estefanía; Servín-González, Luis; Méndez, José-Luis; Delgado, Gabriela; Morales-Espinosa, Rosario; Ponce-Soto, Gabriel-Yaxal; Cocotl-Yañez, Miguel; Soberón-Chávez, Gloria

    2016-12-01

    Rhamnolipids produced by Pseudomonas aeruginosa are biosurfactants with a high biotechnological potential, but their extensive commercialization is limited by the potential virulence of P. aeruginosa and by restrictions in producing these surfactants in heterologous hosts. In this work, we report the characterization of P. aeruginosa strain ATCC 9027 in terms of its genome-sequence, virulence, antibiotic resistance, and its ability to produce mono-rhamnolipids when carrying plasmids with different cloned genes from the type strain PAO1. The genes that were expressed from the plasmids are those coding for enzymes involved in the synthesis of this biosurfactant (rhlA and rhlB), as well as the gene that codes for the RhlR transcriptional regulator. We confirm that strain ATCC 9027 forms part of the PA7 clade, but contrary to strain PA7, it is sensitive to antibiotics and is completely avirulent in a mouse model. We also report that strain ATCC 9027 mono-rhamnolipid synthesis is limited by the expression of the rhlAB-R operon. Thus, this strain carrying the rhlAB-R operon produces similar rhamnolipids levels as PAO1 strain. We determined that strain ATCC 9027 with rhlAB-R operon was not virulent to mice. These results show that strain ATCC 9027, expressing PAO1 rhlAB-R operon, has a high biotechnological potential for industrial mono-rhamnolipid production.

  4. Gene expression patterns and dynamics of the colonization of common bean (Phaseolus vulgaris L.) by highly virulent and weakly virulent strains of Fusarium oxysporum

    Science.gov (United States)

    Niño-Sánchez, Jonathan; Tello, Vega; Casado-del Castillo, Virginia; Thon, Michael R.; Benito, Ernesto P.; Díaz-Mínguez, José María

    2015-01-01

    The dynamics of root and hypocotyl colonization, and the gene expression patterns of several fungal virulence factors and plant defense factors have been analyzed and compared in the interaction of two Fusarium oxysporum f. sp. phaseoli strains displaying clear differences in virulence, with a susceptible common bean cultivar. The growth of the two strains on the root surface and the colonization of the root was quantitatively similar although the highly virulent (HV) strain was more efficient reaching the central root cylinder. The main differences between both strains were found in the temporal and spatial dynamics of crown root and hypocotyl colonization. The increase of fungal biomass in the crown root was considerably larger for the HV strain, which, after an initial stage of global colonization of both the vascular cylinder and the parenchymal cells, restricted its growth to the newly differentiated xylem vessels. The weakly virulent (WV) strain was a much slower and less efficient colonizer of the xylem vessels, showing also growth in the intercellular spaces of the parenchyma. Most of the virulence genes analyzed showed similar expression patterns in both strains, except SIX1, SIX6 and the gene encoding the transcription factor FTF1, which were highly upregulated in root crown and hypocotyl. The response induced in the infected plant showed interesting differences for both strains. The WV strain induced an early and strong transcription of the PR1 gene, involved in SAR response, while the HV strain preferentially induced the early expression of the ethylene responsive factor ERF2. PMID:25883592

  5. Virulence Attributes and Host Response Assays for Determining Pathogenic Potential of Pseudomonas Strains Used in Biotechnology.

    Directory of Open Access Journals (Sweden)

    Azam F Tayabali

    Full Text Available Pseudomonas species are opportunistically pathogenic to humans, yet closely related species are used in biotechnology applications. In order to screen for the pathogenic potential of strains considered for biotechnology applications, several Pseudomonas strains (P.aeruginosa (Pa, P.fluorescens (Pf, P.putida (Pp, P.stutzeri (Ps were compared using functional virulence and toxicity assays. Most Pa strains and Ps grew at temperatures between 28°C and 42°C. However, Pf and Pp strains were the most antibiotic resistant, with ciprofloxacin and colistin being the most effective of those tested. No strain was haemolytic on sheep blood agar. Almost all Pa, but not other test strains, produced a pyocyanin-like chromophore, and caused cytotoxicity towards cultured human HT29 cells. Murine endotracheal exposures indicated that the laboratory reference strain, PAO1, was most persistent in the lungs. Only Pa strains induced pro-inflammatory and inflammatory responses, as measured by elevated cytokines and pulmonary Gr-1 -positive cells. Serum amyloid A was elevated at ≥ 48 h post-exposure by only some Pa strains. No relationship was observed between strains and levels of peripheral leukocytes. The species designation or isolation source may not accurately reflect pathogenic potential, since the clinical strain Pa10752 was relatively nonvirulent, but the industrial strain Pa31480 showed comparable virulence to PAO1. Functional assays involving microbial growth, cytotoxicity and murine immunological responses may be most useful for identifying problematic Pseudomonas strains being considered for biotechnology applications.

  6. Prior Inoculation with Type B Strains of Francisella tularensis Provides Partial Protection against Virulent Type A Strains in Cottontail Rabbits

    Science.gov (United States)

    Brown, Vienna R.; Adney, Danielle R.; Olea-Popelka, Francisco; Bowen, Richard A.

    2015-01-01

    Francisella tularensis is a highly virulent bacterium that is capable of causing severe disease (tularemia) in a wide range of species. This organism is characterized into two distinct subspecies: tularensis (type A) and holarctica (type B) which vary in several crucial ways, with some type A strains having been found to be considerably more virulent in humans and laboratory animals. Cottontail rabbits have been widely implicated as a reservoir species for this subspecies; however, experimental inoculation in our laboratory revealed type A organisms to be highly virulent, resulting in 100% mortality following challenge with 50–100 organisms. Inoculation of cottontail rabbits with the same number of organisms from type B strains of bacteria was found to be rarely lethal and to result in a robust humoral immune response. The objective of this study was to characterize the protection afforded by a prior challenge with type B strains against a later inoculation with a type A strain in North American cottontail rabbits (Sylvilagus spp). Previous infection with a type B strain of organism was found to lengthen survival time and in some cases prevent death following inoculation with a type A2 strain of F. tularensis. In contrast, inoculation of a type A1b strain was uniformly lethal in cottontail rabbits irrespective of a prior type B inoculation. These findings provide important insight about the role cottontail rabbits may play in environmental maintenance and transmission of this organism. PMID:26474413

  7. A variable region within the genome of Streptococcus pneumoniae contributes to strain-strain variation in virulence.

    Directory of Open Access Journals (Sweden)

    Richard M Harvey

    2011-05-01

    Full Text Available The bacterial factors responsible for the variation in invasive potential between different clones and serotypes of Streptococcus pneumoniae are largely unknown. Therefore, the isolation of rare serotype 1 carriage strains in Indigenous Australian communities provided a unique opportunity to compare the genomes of non-invasive and invasive isolates of the same serotype in order to identify such factors. The human virulence status of non-invasive, intermediately virulent and highly virulent serotype 1 isolates was reflected in mice and showed that whilst both human non-invasive and highly virulent isolates were able to colonize the murine nasopharynx equally, only the human highly virulent isolates were able to invade and survive in the murine lungs and blood. Genomic sequencing comparisons between these isolates identified 8 regions >1 kb in size that were specific to only the highly virulent isolates, and included a version of the pneumococcal pathogenicity island 1 variable region (PPI-1v, phage-associated adherence factors, transporters and metabolic enzymes. In particular, a phage-associated endolysin, a putative iron/lead permease and an operon within PPI-1v exhibited niche-specific changes in expression that suggest important roles for these genes in the lungs and blood. Moreover, in vivo competition between pneumococci carrying PPI-1v derivatives representing the two identified versions of the region showed that the version of PPI-1v in the highly virulent isolates was more competitive than the version from the less virulent isolates in the nasopharyngeal tissue, blood and lungs. This study is the first to perform genomic comparisons between serotype 1 isolates with distinct virulence profiles that correlate between mice and humans, and has highlighted the important role that hypervariable genomic loci, such as PPI-1v, play in pneumococcal disease. The findings of this study have important implications for understanding the processes that

  8. Decreased virulence of a pneumolysin-deficient strain of Streptococcus pneumoniae in murine meningitis.

    Science.gov (United States)

    Wellmer, Andreas; Zysk, Gregor; Gerber, Joachim; Kunst, Tammo; Von Mering, Matthias; Bunkowski, Stefanie; Eiffert, Helmut; Nau, Roland

    2002-11-01

    Pneumolysin, neuraminidases A and B, and hyaluronidase are virulence factors of Streptococcus pneumoniae that appear to be involved in the pathogenesis of meningitis. In a murine model of meningitis after intracerebral infection using mutants of S. pneumoniae D39, only mice infected with a pneumolysin-deficient strain were healthier at 32 and 36 h, had lower bacterial titers in blood at 36 h, and survived longer than the D39 parent strain. Cerebellar and spleen bacterial titers, meningeal inflammation, and neuronal damage scores remained uninfluenced by the lack of any of the virulence factors.

  9. Temporal Profile of Biofilm Formation, Gene Expression and Virulence Analysis in Candida albicans Strains.

    Science.gov (United States)

    de Barros, Patrícia Pimentel; Rossoni, Rodnei Dennis; De Camargo Ribeiro, Felipe; Junqueira, Juliana Campos; Jorge, Antonio Olavo Cardoso

    2017-04-01

    The characterization of Candida albicans strains with different degrees of virulence became very useful to understand the mechanisms of fungal virulence. Then, the objective of this study was to assess and compare the temporal profiles of biofilms formation, gene expression of ALS1, ALS3, HWP1, BCR1, EFG1, TEC1, SAP5, PLB2 and LIP9 and virulence in Galleria mellonella of C. albicans ATCC18804 and a clinical sample isolated from an HIV-positive patient (CA60). Although the CFU/mL counting was higher in biofilms formed in vitro by ATCC strain, the temporal profile of the analysis of the transcripts of the C. albicans strains was elevated to Ca60 compared to strain ATCC, especially in the genes HWP1, ALS3, SAP5, PLB2 and LIP9 (up regulation). Ca60 was more pathogenic for G. mellonella in the survival assay (p = 0.0394) and hemocytes density (p = 0.0349), agreeing with upregulated genes that encode the expression of hyphae and hydrolase genes of Ca60. In conclusion, the C. albicans strains used in this study differ in the amount of biofilm formation, virulence in vivo and transcriptional profiles of genes analyzed that can change factors associated with colonization, proliferation and survival of C. albicans at different niches. SAP5 and HWP1 were the genes more expressed in the formation of biofilm in vitro.

  10. Legionella pneumophila pangenome reveals strain-specific virulence factors

    Directory of Open Access Journals (Sweden)

    Peris-Bondia Francesc

    2010-03-01

    Full Text Available Abstract Background Legionella pneumophila subsp. pneumophila is a gram-negative γ-Proteobacterium and the causative agent of Legionnaires' disease, a form of epidemic pneumonia. It has a water-related life cycle. In industrialized cities L. pneumophila is commonly encountered in refrigeration towers and water pipes. Infection is always via infected aerosols to humans. Although many efforts have been made to eradicate Legionella from buildings, it still contaminates the water systems. The town of Alcoy (Valencian Region, Spain has had recurrent outbreaks since 1999. The strain "Alcoy 2300/99" is a particularly persistent and recurrent strain that was isolated during one of the most significant outbreaks between the years 1999-2000. Results We have sequenced the genome of the particularly persistent L. pneumophila strain Alcoy 2300/99 and have compared it with four previously sequenced strains known as Philadelphia (USA, Lens (France, Paris (France and Corby (England. Pangenome analysis facilitated the identification of strain-specific features, as well as some that are shared by two or more strains. We identified: (1 three islands related to anti-drug resistance systems; (2 a system for transport and secretion of heavy metals; (3 three systems related to DNA transfer; (4 two CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats systems, known to provide resistance against phage infections, one similar in the Lens and Alcoy strains, and another specific to the Paris strain; and (5 seven islands of phage-related proteins, five of which seem to be strain-specific and two shared. Conclusions The dispensable genome disclosed by the pangenomic analysis seems to be a reservoir of new traits that have mainly been acquired by horizontal gene transfer and could confer evolutionary advantages over strains lacking them.

  11. A virulent parent with probiotic progeny: comparative genomics of Escherichia coli strains CFT073, Nissle 1917 and ABU 83972

    DEFF Research Database (Denmark)

    Vejborg, Rebecca Munk; Friis, Carsten; Hancock, Viktoria

    2010-01-01

    ) with the highly virulent uropathogen CFT073. Only relatively minor genetic variations were found between the isolates, suggesting that the three strains may have originated from the same virulent ancestral parent. Interestingly, Nissle 1917 (a gut commensal strain) was more similar to CFT073 with respect...

  12. Characterization of Nomuraea rileyi strains using polymorphic DNA, virulence and enzyme activity

    Directory of Open Access Journals (Sweden)

    Vargas Lúcia Rosane Bertholdo

    2003-01-01

    Full Text Available The characterization of entomopathogenic microorganisms is important for the selection of more effective strains for use in integrated pest-control programs. Five Nomuraea rileyi strains (SA86101, GU87401, SR86151, CG128 and VA9101 were characterized using random amplified polymorphic DNA (RAPD analysis, virulence studies and assessment of chitinolytic and proteolytic activity. RAPD analysis divided the strains into two groups with a similarity coefficient of 0,76%, group 1 consisting of strains SA86101, GU87401 and SR86151 and group 2 of strains CG128 and VA9101. The LT50 varied from 165h with strain VA9101 to 246h with strain GU87401. Chitinolytic and proteolytic activity of the fungi after 144h growth in minimal medium were tested using colloidal chitin as substrate. All strains exhibited enzyme activity, with strain VA9101 having the highest chitinase activity (0,0040 mumol/mL/min the 40ºC and strain SA86101 the highest proteolytic activity. No relationship was found between RAPD analysis, virulence and chitinase or protease activity.

  13. Complete genome sequence of a virulent Streptococcus agalactiae strain 138P isolated from disease Nile tilapia

    Science.gov (United States)

    The complete genome of a virulent Streptococcus agalactiae strain 138P is 1838701 bp in size, containing 1831 genes. The genome has 1593 coding sequences, 152 pseudo genes, 16 rRNAs, 69 tRNAs, and 1 non-coding RNA. The annotation of the genome is added by the NCBI Prokaryotic Genome Annotation Pipel...

  14. Clinicopathological characterization of two recombinant Newcastle disease viruses derived from a virulent Chinese strain

    Science.gov (United States)

    Four-week-old white Leghorn chickens were inoculated intraconjunctivally with either a virulent recombinant clone of Newcastle disease virus (NDV), rZJ1, or a modified rZJ1, containing a green fluorescent protein (GFP), (rZJ1-GFP). The ZJ1 parent strain was responsible for NDV outbreaks in Southern...

  15. Virulence of Entomopathogenic Nematodes to Plum Curculio, Conotrachelus nenuphar: Effects of Strain, Temperature, and Soil Type.

    Science.gov (United States)

    Shapiro-Ilan, David I; Leskey, Tracy C; Wright, Starker E

    2011-09-01

    The plum curculio, Conotrachelus nenuphar, is a major pest of stone and pome fruit (e.g., apples, pears, peaches, cherries, etc.). Entomopathogenic nematodes (Steinernema spp. and Heterorhabditis spp.) may be used to control the larval stage of C. nenuphar following fruit drop. Indeed, certain entomopathogenic nematodes species have previously been shown to be highly effective in killing C. nenuphar larvae in laboratory and field trials. In field trials conducted in the Southeastern, USA, Steinernema riobrave has thus far been shown to be the most effective species. However, due to lower soil temperatures, other entomopathogenic nematode strains or species may be more appropriate for use against C. nenuphar in the insect's northern range. Thus, the objective of this study was to conduct a broad screening of entomopathogenic nematodes. Under laboratory conditions, we determined the virulence of 13 nematode strains (comprising nine species) in two different soils (a loam and clay-loam) and three different temperatures (12°C, 18°C, and 25°C). Superior virulence was observed in S. feltiae (SN strain), S. rarum (17 C&E strain), and S. riobrave (355 strain). Promising levels of virulence were also observed in others including H. indica (HOM1 strain), H. bacteriophora (Oswego strain), S. kraussei, and S. carpocapsae (Sal strain). All nematode treatments were affected by temperature with the highest virulence observed at the highest temperature (25°C). In future research, field tests will be used to further narrow down the most suitable nematode species for C. nenuphar control.

  16. White spot syndrome virus strains of different virulence induce distinct immune response in Cherax quadricarinatus.

    Science.gov (United States)

    Gao, Meiling; Li, Fang; Xu, Limei; Zhu, Xiaoming

    2014-07-01

    In this study, we identified three white spot syndrome virus (WSSV) strains (WSSV-CN01, WSSV-CN02 and WSSV-CN03) with significant differences in virulence. Among them, WSSV-CN01 caused significant higher and earlier mortality in redclaw crayfish Cherax quadricarinatus, thus was determined as high-virulent, while WSSV-CN02 and WSSV-CN03 were moderate-virulent and low-virulent. By investigating the total number of the circulating haemocytes and the activity of immune relative enzymes, we demonstrated that the different virulent WSSV strains induced distinct immune response in the host. Notably, a dramatic reduction of circulating haemocytes was observed in the crayfish infected with WSSV-CN01 and WSSV-CN02 but not WSSV-CN03. Further analysis revealed that cell death induced by WSSV-CN01 and WSSV-CN02 might be responsible for the decrease of circulating haemocytes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. IDENTIFICATION OF A FLAVOBACTERIUM STRAIN VIRULENT AGAINT GIARDIA LAMBLIA CYSTS

    Science.gov (United States)

    We have isolated a bacterial strain capable of killing the cyst form of Giardia lamblia, from a Kentucky stream. This bacterium, designated Sun4, is a Gram negative, aerobic rod which produces a yellow pigment, but not of the flexirubin-type. Although true gliding motility has no...

  18. Investigation of possible virulence factors in Candida strains isolated ...

    African Journals Online (AJOL)

    Background: The Candida species, which are one of the most common causes of nosocomial bloodstream infections, present with high mortality and morbidity rates. This study aims to investigate the production of esterase, phospholipase, proteinase, and biofilm formation ability of the Candida strains isolated from the ...

  19. Reconstructing the highly virulent Classical Swine Fever Virus strain Koslov

    DEFF Research Database (Denmark)

    Fahnøe, Ulrik; Pedersen, Anders Gorm; Nielsen, Jens

    DNA by site directed mutagenesis, removing non-synonymous mutations step by step. In vitro testing of modified constructs did indeed lead to fully functional viruses with similar growth kinetics as the wild-type strain. Moreover, viruses rescued from the construct had the ancestral amino acid sequence and...

  20. Unravelling the differences: comparative proteomic analysis of a clonal virulent and an attenuated Histomonas meleagridis strain.

    Science.gov (United States)

    Monoyios, Andreas; Patzl, Martina; Schlosser, Sarah; Hess, Michael; Bilic, Ivana

    2018-02-01

    The current study focused on Histomonas meleagridis, a unicellular protozoan, responsible for histomonosis in poultry. Recently, the occurrence of the disease increased due to the ban of effective chemotherapeutic drugs. Basic questions regarding the molecular biology, virulence mechanisms or even life cycle of the flagellate are still puzzling. In order to address some of these issues, we conducted a comparative proteomic analysis of a virulent and an attenuated H. meleagridis strain traced back to a single cell and propagated in vitro as monoxenic mono-eukaryotic cultures. Using two-dimensional electrophoresis (2-DE) for proteome visualization with computational 2-DE gel image and statistical analysis, upregulated proteins in either of the two H. meleagridis strains were detected. Statistical analysis fulfilling two criteria (≥threefold upregulation and P analysis of 32 protein spots upregulated in gels of the virulent strain identified 17 as H. meleagridis-specific. The identification revealed that these spots belonged to eight different proteins, with the majority related to cellular stress management. Two ubiquitous cellular proteins, actin and enolase, were upregulated in multiple gel positions in this strain, indicating either post-translational modification or truncation, or even both. Additionally, a known virulence factor named legumain cysteine peptidase was also detected. In contrast to this, mass spectrometric analysis of 49 protein spots, upregulated in gels of the attenuated strain, singled out 32 spots as specific for the flagellate. These spots were shown to correspond to 24 different proteins that reflect the increased metabolism, in vitro adaptation of the parasite, and amoeboid morphology. In addition to H. meleagridis proteins, the analysis identified differential expression of Escherichia coli DH5α proteins that could have been influenced by the co-cultivated H. meleagridis strain, indicating a reciprocal interaction of these two

  1. Characterization of virulence of the Streptococcus suis serotype 2 reference strain Henrichsen S 735 in newborn gnotobiotic pigs

    NARCIS (Netherlands)

    Vecht, U.; Wisselink, H.J.; Stockhofe-Zurwieden, N.; Smith, H.E.

    1996-01-01

    Strain Henrichsen S 735 (NCTC 10234) of Streptococcus suis serotype 2 reference and three other such strains (strains S 4005, S 3921 and T 141) were tested for virulence by inoculating pigs intranasally and intravenously. The taxonomical properties of each strain were determined. Phenotypes were

  2. Virulence potential of Enterococcus gallinarum strains isolated from selected Nigerian traditional fermented foods

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    IYABO C. OLADIPO

    2014-08-01

    Full Text Available Five Enterococcus isolates from some Nigerian traditional fermented foods were identified as Enterococcus gallinarum by using phenotypic and genotypic tests. Safety properties such as antibiotic susceptibility, virulence gene detection, haemolysin, gelatinase and bacteriocin production were determined using standard methods. There was no resistance to clinically relevant antibiotics. Virulence gene for collagen binding antigen and aggregation substance were detected in 60% of the E. gallinarum strains; while surface adhesin was detected in 20%, but none of the strains had cytolysin activator and gelatinase. Phenotype characterizations of the E. gallinarum isolates indicated that none of the isolates produced haemolysin and gelatinase. Enterococcus gallinarum C103 and U82 had no antimicrobial activity against all the selected bacteria pathogens while E. gallinarum W184, T71 and W21 were active against some of the indicator bacteria pathogens. Only E. gallinarum T71 and W21 showed broad spectra of antimicrobial activity. Combination of virulence factors did not appear in these food isolates. Therefore, these strains particularly the two strains with high spectra of antimicrobial activity could be exploited as functional starters in foods.

  3. Genomic sequence and virulence of clonal isolates of vaccinia virus Tiantan, the Chinese smallpox vaccine strain.

    Directory of Open Access Journals (Sweden)

    Qicheng Zhang

    Full Text Available Despite the worldwide eradication of smallpox in 1979, the potential bioterrorism threat from variola virus and the ongoing use of vaccinia virus (VACV as a vector for vaccine development argue for continued research on VACV. In China, the VACV Tiantan strain (TT was used in the smallpox eradication campaign. Its progeny strain is currently being used to develop a human immunodeficiency virus (HIV vaccine. Here we sequenced the full genomes of five TT clones isolated by plaque purification from the TT (752-1 viral stock. Phylogenetic analysis with other commonly used VACV strains showed that TT (752-1 and its clones clustered and exhibited higher sequence diversity than that found in Dryvax clones. The ∼190 kbp genomes of TT appeared to encode 273 open reading frames (ORFs. ORFs located in the middle of the genome were more conserved than those located at the two termini, where many virulence and immunomodulation associated genes reside. Several patterns of nucleotide changes including point mutations, insertions and deletions were identified. The polymorphisms in seven virulence-associated proteins and six immunomodulation-related proteins were analyzed. We also investigated the neuro- and skin- virulence of TT clones in mice and rabbits, respectively. The TT clones exhibited significantly less virulence than the New York City Board of Health (NYCBH strain, as evidenced by less extensive weight loss and morbidity in mice as well as produced smaller skin lesions and lower incidence of putrescence in rabbits. The complete genome sequences, ORF annotations, and phenotypic diversity yielded from this study aid our understanding of the Chinese historic TT strain and are useful for HIV vaccine projects employing TT as a vector.

  4. Genetic diversity and virulence genes in Streptococcus uberis strains isolated from bovine mastitis

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    Rafael Ambrósio Loures

    2017-08-01

    Full Text Available Mastitis is one of the most common and costly infectious diseases in dairy cattle worldwide. This is a multifactorial illness caused by different microorganisms, including virus, yeasts, algae, parasites, and several species of bacteria. Among these bacteria, Streptococcus uberis is an important environmental pathogen that is responsible for a large range of clinical and subclinical mammary infections, especially in intensively managed herds. Despite the increasing importance of this pathogen in the etiology of bovine mastitis, data on its virulence and diversity in Brazilian dairy herds are scarce. The aims of the present study were to investigate the virulence characteristics of S. uberis isolated from bovine mastitis and to assess the molecular epidemiology of the Brazilian isolates using pulsed-field gel electrophoresis (PFGE. In this work, 46 strains of S. uberis isolated from bovine mastitis from 26 Brazilian dairy herds were evaluated regarding their genetic diversity by PFGE using with the SmaI enzyme. Additionally, the presence of the virulence genes skc and pauA, which encode plasminogen activators, and the gene sua, which encodes an adhesion molecule in mammary epithelial cells, were assessed by PCR. Our results showed a high genetic diversity in the population, displaying many different patterns in the PFGE analysis. A high proportion of strains was positive for virulence genes in the sampled population (sua [100%], pauA [91%], and skc [91%]. The high frequency of skc, pauA, and sua genes among the studied strains suggests the importance of these virulence factors, possibly helping S. uberis in the colonization of the bovine mammary gland. Surveys of the genetic and molecular characteristics of this pathogen can improve our knowledge of bacterial activity and identify molecules that have roles in the establishment of the infection. This might help in the development of more effective measures to control and prevent bovine mastitis.

  5. Detection of virulence genes in Uropathogenic E. coli (UPEC strains by Multiplex-PCR method

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    Javad Mohammadi

    2017-06-01

    Full Text Available Background & Objectives: Urinary tract infection caused by E. coli is one of the most common illnesses in all age groups worldwide. Presence of virulence genes is a key factor in bacterial pathogens in uroepithelial cells. The present study was performed to detect iha, iroN, ompT genes in the Uropathogenic E.coli isolates from clinical samples using multiplex-PCR method in Kerman. Materials & Methods: In this descriptive cross-sectional study, 200 samples of patients with urinary tract infections in Kerman hospitals were collected. After biochemical and microbiological tests, all strains were tested with regard to the presence of iha, iroN, and ompT genes using multiplex-PCR method. Results: The results of Multiplex-PCR showed that all specimens had one, two, or three virulence genes simultaneously. The highest and lowest frequency distribution of genes was related to iha (56.7% and iroN (20% respectively. Conclusion: According to the prevalence of urinary tract infection in the community and distribution of resistance and virulence factors, the fast and accurate detection of the strains and virulence genes is necessary

  6. Comparing in vitro and in vivo virulence phenotypes of Burkholderia pseudomallei type G strains.

    Science.gov (United States)

    Lewis, Eric R G; Kilgore, Paul B; Mott, Tiffany M; Pradenas, Gonzalo A; Torres, Alfredo G

    2017-01-01

    Burkholderia pseudomallei (Bpm) is a saprophytic rod-shaped gram-negative bacterium and the causative agent of melioidosis. This disease has previously been described as endemic in areas such as northern Australia and Southeast Asia, but, more recently, a better understanding of the epidemiology of melioidosis indicated that the disease is distributed worldwide, including regions of the Americas and Africa. A 16S-23S rDNA internal transcribed spacer (ITS) typing system has been developed for Bpm and has revealed that ITS types C, E, and hybrid CE are mainly associated with Australia and Southeast Asia while type G strains are more associated with cases of melioidosis in the Western Hemisphere. The purpose of the current study was to determine the in vitro and in vivo virulence profiles of the understudied Bpm type G strains Ca2009, Ca2013a, Mx2013, and 724644 and compared such phenotypes to the commonly studied Bpm type C strain K96243. We evaluated virulence by measuring invasion/uptake and survival of these Bpm strains in murine respiratory epithelial LA-4 cells and alveolar macrophage MH-S cells using different multiplicity of infections (MOIs of 1 and 10). We also calculated the lethal dose 50 values (LD50) in BALB/c mice that were inoculated intranasally with either Ca2009, Ca2013a, or Mx2013. Overall, the virulence and lethality phenotypes of Bpm type G strains were similar to the Bpm type C strain K96243. Additional comparative analyses between the Bpm ITS types may lead to a better understanding of the contribution of the ITS type to the epidemiology and ecology of Bpm strains.

  7. Virulence of a Klebsiella pneumoniae strain carrying the New Delhi metallo-beta-lactamase-1 (NDM-1)

    DEFF Research Database (Denmark)

    Fuursted, Kurt; Schøler, Lone Vedel; Hansen, Frank

    2012-01-01

    The aim of the study was to compare and evaluate virulence in five strains of Klebsiella pneumoniae, including an isolate carrying New Delhi metallo-beta-lactamase-1 (NDM-1). In vivo virulence was assessed using a murine sepsis model and using the nematode Caenorhabditis elegans killing model...

  8. Comparative Genomics of Gardnerella vaginalis Strains Reveals Substantial Differences in Metabolic and Virulence Potential

    Science.gov (United States)

    Yeoman, Carl J.; Yildirim, Suleyman; Thomas, Susan M.; Durkin, A. Scott; Torralba, Manolito; Sutton, Granger; Buhay, Christian J.; Ding, Yan; Dugan-Rocha, Shannon P.; Muzny, Donna M.; Qin, Xiang; Gibbs, Richard A.; Leigh, Steven R.; Stumpf, Rebecca; White, Bryan A.; Highlander, Sarah K.; Nelson, Karen E.; Wilson, Brenda A.

    2010-01-01

    Background Gardnerella vaginalis is described as a common vaginal bacterial species whose presence correlates strongly with bacterial vaginosis (BV). Here we report the genome sequencing and comparative analyses of three strains of G. vaginalis. Strains 317 (ATCC 14019) and 594 (ATCC 14018) were isolated from the vaginal tracts of women with symptomatic BV, while Strain 409-05 was isolated from a healthy, asymptomatic individual with a Nugent score of 9. Principal Findings Substantial genomic rearrangement and heterogeneity were observed that appeared to have resulted from both mobile elements and substantial lateral gene transfer. These genomic differences translated to differences in metabolic potential. All strains are equipped with significant virulence potential, including genes encoding the previously described vaginolysin, pili for cytoadhesion, EPS biosynthetic genes for biofilm formation, and antimicrobial resistance systems, We also observed systems promoting multi-drug and lantibiotic extrusion. All G. vaginalis strains possess a large number of genes that may enhance their ability to compete with and exclude other vaginal colonists. These include up to six toxin-antitoxin systems and up to nine additional antitoxins lacking cognate toxins, several of which are clustered within each genome. All strains encode bacteriocidal toxins, including two lysozyme-like toxins produced uniquely by strain 409-05. Interestingly, the BV isolates encode numerous proteins not found in strain 409-05 that likely increase their pathogenic potential. These include enzymes enabling mucin degradation, a trait previously described to strongly correlate with BV, although commonly attributed to non-G. vaginalis species. Conclusions Collectively, our results indicate that all three strains are able to thrive in vaginal environments, and therein the BV isolates are capable of occupying a niche that is unique from 409-05. Each strain has significant virulence potential, although

  9. Virulence Differences among Melissococcus plutonius Strains with Different Genetic Backgrounds in Apis mellifera Larvae under an Improved Experimental Condition.

    Science.gov (United States)

    Nakamura, Keiko; Yamazaki, Yuko; Shiraishi, Akiyo; Kobayashi, Sota; Harada, Mariko; Yoshiyama, Mikio; Osaki, Makoto; Okura, Masatoshi; Takamatsu, Daisuke

    2016-09-14

    European foulbrood (EFB) caused by Melissococcus plutonius is an important bacterial disease of honeybee larvae. M. plutonius strains can be grouped into three genetically distinct groups (CC3, CC12 and CC13). Because EFB could not be reproduced in artificially reared honeybee larvae by fastidious strains of CC3 and CC13 previously, we investigated a method to improve experimental conditions using a CC3 strain and found that infection with a potassium-rich diet enhanced proliferation of the fastidious strain in larvae at the early stage of infection, leading to the appearance of clear clinical symptoms. Further comparison of M. plutonius virulence under the conditions revealed that the representative strain of CC12 was extremely virulent and killed all tested bees before pupation, whereas the CC3 strain was less virulent than the CC12 strain, and a part of the infected larvae pupated. In contrast, the tested CC13 strain was avirulent, and as with the non-infected control group, most of the infected brood became adult bees, suggesting differences in the insect-level virulence among M. plutonius strains with different genetic backgrounds. These strains and the improved experimental infection method to evaluate their virulence will be useful tools for further elucidation of the pathogenic mechanisms of EFB.

  10. End-point disease investigation for virus strains of intermediate virulence as illustrated by flavivirus infections.

    Science.gov (United States)

    Suen, Willy W; Prow, Natalie A; Setoh, Yin X; Hall, Roy A; Bielefeldt-Ohmann, Helle

    2016-02-01

    Viruses of intermediate virulence are defined as isolates causing an intermediate morbidity/mortality rate in a specific animal model system, involving specific host and inoculation parameters (e.g. dose and route). Therefore, variable disease phenotype may exist between animals that develop severe disease or die and those that are asymptomatic or survive after infection with these isolates. There may also be variability amongst animals within each of these subsets. Such potential variability may confound the use of time-point sacrifice experiments to investigate pathogenesis of this subset of virus strains, as uniformity in disease outcome is a fundamental assumption for time-course sacrifice experiments. In the current study, we examined the disease phenotype, neuropathology, neural infection and glial cell activity in moribund/dead and surviving Swiss white (CD-1) mice after intraperitoneal infection with various Australian flaviviruses, including West Nile virus (WNV) strains of intermediate virulence (WNVNSW2011 and WNVNSW2012), and highly virulent Murray Valley encephalitis virus (MVEV) isolates. We identified notable intragroup variation in the end-point disease in mice infected with either WNVNSW strain, but to a lesser extent in mice infected with MVEV strains. The variable outcomes associated with WNVNSW infection suggest that pathogenesis investigations using time-point sacrifice of WNVNSW-infected mice may not be the best approach, as the assumption of uniformity in outcomes is violated. Our study has therefore highlighted a previously unacknowledged challenge to investigating pathogenesis of virus isolates of intermediate virulence. We have also set a precedent for routine examination of the disease phenotype in moribund/dead and surviving mice during survival challenge experiments.

  11. Characterization of systemic and pneumonic murine models of plague infection using a conditionally virulent strain.

    Science.gov (United States)

    Mellado-Sanchez, Gabriela; Ramirez, Karina; Drachenberg, Cinthia B; Diaz-McNair, Jovita; Rodriguez, Ana L; Galen, James E; Nataro, James P; Pasetti, Marcela F

    2013-03-01

    Yersinia pestis causes bubonic and pneumonic plague in humans. The pneumonic infection is the most severe and invariably fatal if untreated. Because of its high virulence, ease of delivery and precedent of use in warfare, Y. pestis is considered as a potential bioterror agent. No licensed plague vaccine is currently available in the US. Laboratory research with virulent strains requires appropriate biocontainment (i.e., Biosafety Level 3 (BSL-3) for procedures that generate aerosol/droplets) and secure facilities that comply with federal select agent regulations. To assist in the identification of promising vaccine candidates during the early phases of development, we characterized mouse models of systemic and pneumonic plague infection using the Y. pestis strain EV76, an attenuated human vaccine strain that can be rendered virulent in mice under in vivo iron supplementation. Mice inoculated intranasally or intravenously with Y. pestis EV76 in the presence of iron developed a systemic and pneumonic plague infection that resulted in disease and lethality. Bacteria replicated and severely compromised the spleen, liver and lungs. Susceptibility was age dependent, with younger mice being more vulnerable to pneumonic infection. We used these models of infection to assess the protective capacity of newly developed Salmonella-based plague vaccines. The protective outcome varied depending on the route and dose of infection. Protection was associated with the induction of specific immunological effectors in systemic/mucosal compartments. The models of infection described could serve as safe and practical tools for identifying promising vaccine candidates that warrant further potency evaluation using fully virulent strains in BSL-3 settings. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Influence of Temperature on the Physiology and Virulence of the Insect Pathogen Serratia sp. Strain SCBI

    Science.gov (United States)

    Petersen, Lauren M.

    2012-01-01

    The physiology of a newly recognized Serratia species, termed South African Caenorhabditis briggsae Isolate (SCBI), which is both a nematode mutualist and an insect pathogen, was investigated and compared to that of Serratia marcescens Db11, a broad-host-range pathogen. The two Serratia strains had comparable levels of virulence for Manduca sexta and similar cytotoxic activity patterns, but motility and lipase and hemolytic activities differed significantly between them. PMID:23042169

  13. Pathogenicity of a Very Virulent Strain of Marek's Disease Herpesvirus Cloned as Infectious Bacterial Artificial Chromosomes

    Directory of Open Access Journals (Sweden)

    Lorraine P. Smith

    2011-01-01

    Full Text Available Bacterial artificial chromosome (BAC vectors containing the full-length genomes of several herpesviruses have been used widely as tools to enable functional studies of viral genes. Marek's disease viruses (MDVs are highly oncogenic alphaherpesviruses that induce rapid-onset T-cell lymphomas in chickens. Oncogenic strains of MDV reconstituted from BAC clones have been used to examine the role of viral genes in inducing tumours. Past studies have demonstrated continuous increase in virulence of MDV strains. We have previously reported on the UK isolate C12/130 that showed increased virulence features including lymphoid organ atrophy and enhanced tropism for the central nervous system. Here we report the construction of the BAC clones (pC12/130 of this strain. Chickens were infected with viruses reconstituted from the pC12/130 clones along with the wild-type virus for the comparison of the pathogenic properties. Our studies show that BAC-derived viruses induced disease similar to the wild-type virus, though there were differences in the levels of pathogenicity between individual viruses. Generation of BAC clones that differ in the potential to induce cytolytic disease provide the opportunity to identify the molecular determinants of increased virulence by direct sequence analysis as well as by using reverse genetics approaches on the infectious BAC clones.

  14. Assessment of virulence diversity of methicillin-resistant Staphylococcus aureus strains with a Drosophila melanogaster infection model

    Directory of Open Access Journals (Sweden)

    Wu Kaiyu

    2012-11-01

    Full Text Available Abstract Background Staphylococcus aureus strains with distinct genetic backgrounds have shown different virulence in animal models as well as associations with different clinical outcomes, such as causing infection in the hospital or the community. With S. aureus strains carrying diverse genetic backgrounds that have been demonstrated by gene typing and genomic sequences, it is difficult to compare these strains using mammalian models. Invertebrate host models provide a useful alternative approach for studying bacterial pathogenesis in mammals since they have conserved innate immune systems of biological defense. Here, we employed Drosophila melanogaster as a host model for studying the virulence of S. aureus strains. Results Community-associated methicillin-resistant S. aureus (CA-MRSA strains USA300, USA400 and CMRSA2 were more virulent than a hospital-associated (HA-MRSA strain (CMRSA6 and a colonization strain (M92 in the D. melanogaster model. These results correlate with bacterial virulence in the Caenorhabditis elegans host model as well as human clinical data. Moreover, MRSA killing activities in the D. melanogaster model are associated with bacterial replication within the flies. Different MRSA strains induced similar host responses in D. melanogaster, but demonstrated differential expression of common bacterial virulence factors, which may account for the different killing activities in the model. In addition, hemolysin α, an important virulence factor produced by S. aureus in human infections is postulated to play a role in the fly killing. Conclusions Our results demonstrate that the D. melanogaster model is potentially useful for studying S. aureus pathogenicity. Different MRSA strains demonstrated diverse virulence in the D. melanogaster model, which may be the result of differing expression of bacterial virulence factors in vivo.

  15. iTRAQ-based comparative proteomic analysis of Vero cells infected with virulent and CV777 vaccine strain-like strains of porcine epidemic diarrhea virus.

    Science.gov (United States)

    Guo, Xiaozhen; Hu, Han; Chen, Fangzhou; Li, Zhonghua; Ye, Shiyi; Cheng, Shuang; Zhang, Mengjia; He, Qigai

    2016-01-01

    The re-emerging porcine epidemic diarrhea virus (PEDV) variant related diarrhea has been documented in China since late 2010 and now with global distribution. Currently, a virulent PEDV CH/YNKM-8/2013 and a CV777 vaccine strain-like AH-M have been successfully isolated from the clinical samples. To dissect out the underlying pathogenic mechanism of virulent PEDV and clarify the differences between virulent and CV777 vaccine strain-like PEDV infections, we performed an iTRAQ-based comparative quantitative proteomic study of Vero cells infected with both PEDV strains. A total of 661 and 474 differentially expressed proteins were identified upon virulent and CV777 vaccine strain-like isolates infection, respectively. Ingenuity Pathway Analysis was employed to investigate the canonical pathways and functional networks involved in both PEDV infections. Comprehensive studies have revealed that the PEDV virulent strain suppressed protein synthesis of Vero cells through down-regulating mTOR as well as its downstream targets 4EBP1 and p70S6K activities, which were validated by immunoblotting. In addition, the virulent strain could activate NF-κB pathway more intensively than the CV777 vaccine strain-like isolate, and elicit stronger inflammatory cascades as well. These data might provide new insights for elucidating the specific pathogenesis of PEDV infection, and pave the way for the development of effective therapeutic strategies. Porcine epidemic diarrhea is now worldwide distributed and causing huge economic losses to swine industry. The immunomodulation and pathogenesis between PEDV and host, as well as the difference between virulent and attenuated strains of PEDV infections are still largely unknown. In this study, we presented for the first application of proteomic analysis to compare whole cellular protein alterations induced by virulent and CV777 vaccine strain-like PEDV infections, which might contribute to understand the pathogenesis of PEDV and anti

  16. Molecular and virulence characterization of Toxoplasma gondii strains isolated from humans in Portugal.

    Science.gov (United States)

    Vilares, Anabela; Gargaté, Maria João; Ferreira, Idalina; Martins, Susana; Gomes, João Paulo

    2017-03-01

    Toxoplasma gondii is an apicomplexan parasite responsible for toxoplasmosis which infects all warm-blooded vertebrates, including mammals and birds. The majority of studies conducted in Europe have revealed that more than 80 % of strains isolated from human infections belong to genotype II, whereas genotypes I and III are responsible for a small number of cases. Atypical and recombinant strains are generally associated with more severe infections. In Portugal, there is a lack of data concerning genetic diversity as the classical typing studies in humans have never been performed. We aimed to determine the Sag2 and microsatellite-based (TUB2, TgM-A, W35, B17, B18) genotypes of T. gondii isolated from humans in Portugal, as well as to study their virulence in mice. We analyzed 48 strains from congenital and acquired toxoplasmosis collected during the last two decades. Sag2-based genotyping of T. gondii was achieved in all 48 strains where 35 (73 %) were classified as type II and 13 (27 %) were type I. The multilocus PCR of five microsatellites allowed the classification of 10 strains (21 %) as recombinant strains that had been previously identified as type II or I by Sag2 typing. Seven out of the 48 strains, including three type I, three recombinant, and one type I, were virulent in mice. This study constitutes the first evidence of recombinant strains circulating in Portugal in humans from congenital infection, highlighting the need for a better evaluation of these strains as their phenotype is still barely understood.

  17. Occurrence of virulence factors and antimicrobial resistance in Pasteurella multocida strains isolated from slaughter cattle in Iran

    National Research Council Canada - National Science Library

    Khamesipour, Faham; Momtaz, Hassan; Azhdary Mamoreh, Morteza

    2014-01-01

    A total of 30 Pasteurella multocida strains isolated from 333 pneumonic and apparently health slaughter cattle were examined for capsule biosynthesis genes and 23 virulence-associated genes by polymerase chain reaction (PCR...

  18. Influence of Triatoma dimidiata in Modulating the Virulence of Trypanosoma cruzi Mexican Strains

    Directory of Open Access Journals (Sweden)

    E. Guzman-Marin

    2012-01-01

    Full Text Available The epidemiology of Chagas disease is complex. There are different vectors and reservoirs and different clinical manifestations. In order to assess whether the biological behavior of three strains isolated in southeastern Mexico (H4 isolated from human, Z17 isolated from Didelphis sp., and V isolated from T. dimidiata could be modified during passage through the vector T. dimidiata, the parasitemia curve, the amount of amastigote nests, and mortality of BALB/c infected with blood trypomastigotes of T. cruzi were evaluated. Strains were maintained in continuous passage from mouse to mouse and in animals infected with metacyclic trypomastigotes. The parasitemia curves were significantly different ( between mice to mice and triatoma to mice groups in strains H4 and Z17, and was also observed fewer amastigote nests in cardiac tissue ( strain H4 with higher number versus all groups and Z17 between mice to mice and triatoma to mice 45 days after inoculation. It is concluded that T. dimidiata influences in modulating the virulence of strains of T. cruzi in the region. Further studies of the intestinal tract of the insect in search for some protein molecules involved in regulating may clarify the virulence of the parasite.

  19. Phenotypic characterization of an international Pseudomonas aeruginosa reference panel: strains of cystic fibrosis (CF) origin show less in vivo virulence than non-CF strains.

    Science.gov (United States)

    Cullen, Louise; Weiser, Rebecca; Olszak, Tomasz; Maldonado, Rita F; Moreira, Ana S; Slachmuylders, Lisa; Brackman, Gilles; Paunova-Krasteva, Tsvetelina S; Zarnowiec, Paulina; Czerwonka, Grzegorz; Reilly, James; Drevinek, Pavel; Kaca, Wieslaw; Melter, Oto; De Soyza, Anthony; Perry, Audrey; Winstanley, Craig; Stoitsova, Stoyanka R; Lavigne, Rob; Mahenthiralingam, Eshwar; Sá-Correia, Isabel; Coenye, Tom; Drulis-Kawa, Zuzanna; Augustyniak, Daria; Valvano, Miguel A; McClean, Siobhán

    2015-10-01

    Pseudomonas aeruginosa causes chronic lung infections in people with cystic fibrosis (CF) and acute opportunistic infections in people without CF. Forty-two P. aeruginosa strains from a range of clinical and environmental sources were collated into a single reference strain panel to harmonise research on this diverse opportunistic pathogen. To facilitate further harmonized and comparable research on P. aeruginosa, we characterized the panel strains for growth rates, motility, virulence in the Galleria mellonella infection model, pyocyanin and alginate production, mucoid phenotype, LPS pattern, biofilm formation, urease activity, and antimicrobial and phage susceptibilities. Phenotypic diversity across the P. aeruginosa panel was apparent for all phenotypes examined, agreeing with the marked variability seen in this species. However, except for growth rate, the phenotypic diversity among strains from CF versus non-CF sources was comparable. CF strains were less virulent in the G. mellonella model than non-CF strains (P = 0.037). Transmissible CF strains generally lacked O-antigen, produced less pyocyanin and had low virulence in G. mellonella. Furthermore, in the three sets of sequential CF strains, virulence, O-antigen expression and pyocyanin production were higher in the earlier isolate compared to the isolate obtained later in infection. Overall, this full phenotypic characterization of the defined panel of P. aeruginosa strains increases our understanding of the virulence and pathogenesis of P. aeruginosa and may provide a valuable resource for the testing of novel therapies against this problematic pathogen.

  20. Nucleotide Sequence-Homology-Independent Breakdown of Transgenic Resistance by More Virulent Virus Strains and a Potential Solution

    OpenAIRE

    Kung, Yi-Jung; You, Bang-Jau; Raja, Joseph A. J.; Chen, Kuan-Chun; Huang, Chiung-Huei; Bau, Huey-Jiunn; Yang, Ching-Fu; Huang, Chung-Hao; Chang, Chung-Ping; Yeh, Shyi-Dong

    2015-01-01

    Controlling plant viruses by genetic engineering, including the globally important Papaya ringspot virus (PRSV), mainly involves coat protein (CP) gene mediated resistance via post-transcriptional gene silencing (PTGS). However, the breakdown of single- or double-virus resistance in CP-gene-transgenic papaya by more virulent PRSV strains has been noted in repeated field trials. Recombination analysis revealed that the gene silencing suppressor HC-Pro or CP of the virulent PRSV strain 5-19 is ...

  1. Specific selection for virulent urinary tract infectious Escherichia coli strains during catheter-associated biofilm formation

    DEFF Research Database (Denmark)

    Ferrieres, Lionel; Hancock, Viktoria; Klemm, Per

    2007-01-01

    Biofilm-associated bacterial infections have a major impact on artificial implants such as urinary catheters, often with devastating consequences. The capacity of a microorganism to form a biofilm on a surface depends on the nature of the surface and its conditioning. When a urinary catheter...... microorganisms can attach. Urinary tract infectious (UTI) Escherichia coli range in pathogenicity and the damage they cause - from benign asymptomatic bacteriuria (ABU) strains, which inflict no or few problems to the host, to uropathogenic E. coli (UPEC) strains, which are virulent and often cause severe...... symptoms and complications. We have found that whereas ABU strains produce better biofilms on polystyrene and glass, UPEC strains have a clear competitive advantage during biofilm growth on catheter surfaces. Our results indicate that some silicone and silicone-latex catheters actually select...

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

    Science.gov (United States)

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

    2012-02-01

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

  3. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. [Investigation of the virulence genes in methicillin-resistant Staphylococcus aureus strains isolated from biomaterial surfaces].

    Science.gov (United States)

    Sudağidan, Mert; Cavuşoğlu, Cengiz; Bacakoğlu, Feza

    2008-01-01

    Staphylococci are the most important agents of nosocomial infections originating from biomaterials. The aim of this study was to investigate the presence of virulence genes and their phenotypic expressions in 11 methicillin-resistant Staphylococcus aureus strains isolated from the surfaces of clinically used biomaterials of 48 thorasic intensive-care unit patients. By the use of specific primers, the presence of genes encoding the attachment and biofilm production (icaA, icaC, bap), methicillin resistance (mecA), enterotoxins A-E (sea, seb, sec, sed, see), toxic shock syndrome toxin (tst), exfoliative toxins A and B (eta and etb), alpha- and beta-hemolysins (hla and hlb), staphylococcal exotoxin-like protein-1 (set1), proteases (sspA, sspB, aur, serine proteaz gene), lipase (geh) and the regulatory genes (sarA and agrCA) were investigated by polymerase chain reaction (PCR). The phenotypic properties of the isolates such as biofilm formation, antibiotic susceptibility, extracellular protease and lipase production were also evaluated. None of the isolates were found to be biofilm and/or slime producers, however, all strains were found to have icaA gene which is responsible for biofilm formation. Nevertheless the presence of icaC and bap genes that are also responsible for biofilm formation were not detected. All the strains have had mecA gene and were resistant to oxacillin, penicilin G and gentamicin, while 10 were also resistant to erythromycin and nine were also resistant to ofloxacin. The isolates were susceptible to vancomycin, teicoplanin and co-trimoxazole. Screening of toxin and regulatory genes revealed that all the strains harboured sea, set1, hla, hlb and sarA genes. The phenotypic tests for the determination of extracellular protease production revealed that all the strains formed very weak zones on skim milk and milk agar plates, and yielded negative results on casein agar plates. Furthermore, all strains were found to harbour sspA, sspB, aur and serine

  5. Comparative analysis of the pathogenic mechanisms of street rabies virus strains with different virulence levels.

    Science.gov (United States)

    Yin, Jing Feng; Ding, Yu Lin; Huang, Ying; Tao, Xiao Yan; Li, Hao; Yu, Peng Cheng; Shen, Xin Xin; Jiao, Wen Tao; Liang, Guo Dong; Tang, Qing; Wang, Feng Long

    2014-10-01

    To characterize two strains of street rabies virus (RABV) isolated from the brain tissue of cattle from Inner Mongolia. Differences in the histopathological and ultrastructural changes in the brain tissue of infected mice were determined to reveal variation in the pathogenesis of infection between street rabies virus strains. Ten-day-old mice were intracranially inoculated with one of three virus strains and brain tissue harvested when the mice were moribund. Various histopathological and ultrastructural markers of disease were then compared between the groups. Infection with the street virus strain CNM1101C resulted in severe neuronal dendrites damage, but only mild cell apoptosis, T lymphocyte infiltration and microglial activation. Infection with the other street virus strain, CNM1103C, was characterized by cell apoptosis, T lymphocyte infiltration and microglial activation as well as dendrites damage. However, in comparison, infection with the attenuated virus strain CTN caused severe T lymphocyte infiltration, microglial activation and cell apoptosis, but left the neuronal dendrites intact. The two street rabies virus strains isolated from cattle from Inner Mongolia had different levels of virulence and caused distinct pathological changes in infected mice. Therefore, we concluded that different pathogenic mechanisms exist between different RABV strains. Copyright © 2014 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

  6. 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.

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

    Science.gov (United States)

    Bessen, Debra E

    2016-06-01

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

  8. [A comparative analysis of genomes of virulent and avirulent strains of Vibrio cholerae O139].

    Science.gov (United States)

    Eroshenko, G A; Osin, A V; Shchelkanova, E Iu; Smirnova, N I

    2004-01-01

    A comparative analysis of the genome of V. cholerae O139 strains isolated in Russia's territory from patients with cholera and from the environment showed essential differences in their structures. The genome of clinical strains possessed all tested genes associated with virulence (ctxAB, zot, ace, rstC, rtxA, hap, toxR and toxT) and the at-tRS site for the CTXp phage DNA integration. As for the O139 V. cholerae chromosome strains isolated from water, 70% of the studied genes (ctxAB, zot, ace, rstC, tcpA, and toxT) and the attRS sequence were not detected in them. A lack of the key virulence genes in O139-serogroup "water" vibrios, including genes of toxin-coregulated adhesion pili. (that are receptors for the CTXp phage), and of the attachment site of the above phage are indicative of that the O139 V. cholerae strains isolated from open water sources located in different Russia's regions are epidemically negligible.

  9. Comparison of the virulence potential of Acinetobacter strains from clinical and environmental sources.

    Directory of Open Access Journals (Sweden)

    Azam F Tayabali

    Full Text Available Several Acinetobacter strains have utility for biotechnology applications, yet some are opportunistic pathogens. We compared strains of seven Acinetobacter species (baumannii, Ab; calcoaceticus, Ac; guillouiae, Ag; haemolyticus, Ah; lwoffii, Al; junii, Aj; and venetianus, Av-RAG-1 for their potential virulence attributes, including proliferation in mammalian cell conditions, haemolytic/cytolytic activity, ability to elicit inflammatory signals, and antibiotic susceptibility. Only Ah grew at 10(2 and 10(4 bacteria/well in mammalian cell culture medium at 37°C. However, co-culture with colonic epithelial cells (HT29 improved growth of all bacterial strains, except Av-RAG-1. Cytotoxicity of Ab and Ah toward HT29 was at least double that of other test bacteria. These effects included bacterial adherence, loss of metabolism, substrate detachment, and cytolysis. Only Ab and Ah exhibited resistance to killing by macrophage-like J774A.1 cells. Haemolytic activity of Ah and Av-RAG-1 was strong, but undetectable for other strains. When killed with an antibiotic, Ab, Ah, Aj and Av-RAG-1 induced 3 to 9-fold elevated HT29 interleukin (IL-8 levels. However, none of the strains altered levels of J774A.1 pro-inflammatory cytokines (IL-1β, IL-6 and tumor necrosis factor-α. Antibiotic susceptibility profiling showed that Ab, Ag and Aj were viable at low concentrations of some antibiotics. All strains were positive for virulence factor genes ompA and epsA, and negative for mutations in gyrA and parC genes that convey fluoroquinolone resistance. The data demonstrate that Av-RAG-1, Ag and Al lack some potentially harmful characteristics compared to other Acinetobacter strains tested, but the biotechnology candidate Av-RAG-1 should be scrutinized further prior to widespread use.

  10. Genotypic diversity and virulence markers of Yersinia enterocolitica biotype 1A strains isolated from clinical and non-clinical origins.

    Science.gov (United States)

    Campioni, Fábio; Falcão, Juliana P

    2014-03-01

    Yersinia enterocolitica biotype 1A (B1A) strains are considered as non-pathogenic; however, some reports have identified some strains as the causal agents of infection. In South America, few studies molecularly characterized the strains of this biotype. This work typed 51 B1A strains isolated from clinical and non-clinical sources from Brazil and Chile by Enterobacterial Repetitive Intergenic Consensus-PCR (ERIC-PCR) to elucidate their genotypic diversity, and verify the distribution of 11 virulence markers by PCR. The strains were divided into two groups, ERIC-A and ERIC-B, clustered independently of their clinical or non-clinical origin. No differences were observed in the frequencies of the virulence markers between clinical and non-clinical strains. However, the genes ystB, hreP and myfA occurred exclusively in the strains of the group ERIC-A. Some clinical and non-clinical strains were clustered in the same genetic group and presented the same number of virulence markers, which might suggest the role of the environment and food as a potential source of infection for humans and animals. The results corroborate with the hypothesis that B1A strains are divided into two main clusters that differ in the frequency of some virulence markers, a fact observed for the first time in South American strains. © 2013 APMIS. Published by John Wiley & Sons Ltd.

  11. Molecular evolution of virulence in natural field strains of Xanthomonas campestris pv. vesicatoria.

    Science.gov (United States)

    Gassmann, W; Dahlbeck, D; Chesnokova, O; Minsavage, G V; Jones, J B; Staskawicz, B J

    2000-12-01

    The avrBs2 avirulence gene of the bacterial plant pathogen Xanthomonas campestris pv. vesicatoria triggers disease resistance in pepper plants containing the Bs2 resistance gene and contributes to bacterial virulence on susceptible host plants. We studied the effects of the pepper Bs2 gene on the evolution of avrBs2 by characterizing the molecular basis for virulence of 20 X. campestris pv. vesicatoria field strains that were isolated from disease spots on previously resistant Bs2 pepper plants. All field strains tested were complemented by a wild-type copy of avrBs2 in their ability to trigger disease resistance on Bs2 plants. DNA sequencing revealed four mutant alleles of avrBs2, two of which consisted of insertions or deletions of 5 nucleotides in a repetitive region of avrBs2. The other two avrBs2 alleles were characterized by point mutations with resulting single amino acid changes (R403P or A410D). We generated isogenic X. campestris pv. vesicatoria strains by chromosomal avrBs2 gene exchange to study the effects of these mutations on the dual functions of avrBs2 in enhancing bacterial virulence and inducing plant resistance by in planta bacterial growth experiments. The deletion of 5 nucleotides led to loss of avrBs2-induced resistance on Bs2 pepper plants and abolition of avrBs2-mediated enhancement of fitness on susceptible plants. Significantly, the point mutations led to minimal reduction in virulence function of avrBs2 on susceptible pepper plants, with either minimal (R403P allele) or an intermediate level of (A410D allele) triggering of resistance on Bs2 plants. Consistent with the divergent selection pressures on avrBs2 exerted by the Bs2 resistance gene, our results show that avrBs2 is evolving to decrease detection by the Bs2 gene while at the same time maintaining its virulence function.

  12. Differences in the stress tolerances of Vibrio parahaemolyticus strains due to their source and harboring of virulence genes.

    Science.gov (United States)

    Hasegawa, Akio; Hara-Kudo, Yukiko; Ogata, Kikuyo; Saito, Shioko; Sugita-Konishi, Yoshiko; Kumagai, Susumu

    2013-08-01

    To investigate the diversity of stress tolerance levels in Vibrio parahaemolyticus, 200 V. parahaemolyticus strains isolated from various coastal environments, seafood, and human clinical cases were exposed to acid, low-osmolality, freezing-thawing, and heat stresses. Tolerance against acid stress was higher in the virulent (tdh- and/or trh-positive) strains than in the avirulent (tdh- and trh-negative) strains. Tolerance against low-osmolality, freezing-thawing, and heat stresses was higher in the clinical strains of tdh- and/or trh-positive V. parahaemolyticus than in the coastal environment- and seafood-originated strains of tdh and/or trh-positive V. parahaemolyticus. Tolerance against acid stress was higher in the strains isolated from coastal seawater at ≤15°C than in the strains isolated at ≥20°C. Tolerance against heat stress was higher in the avirulent strains than the virulent strains, and in the strains isolated from coastal seawater at ≥20°C than the strains isolated from coastal seawater at ≤15°C. Therefore, this study demonstrated that the diversity of stress tolerance levels in V. parahaemolyticus strains depended on their source and whether they harbored virulence genes. In particular, there was significantly greater tolerance against acid in the virulence gene-harboring strains and strains isolated from low-temperature seawater. Because the stress tolerances of V. parahaemolyticus have direct influences for the survival in environment and food, it is important for the prevention of foodborne infection to control the stress-tolerant strains.

  13. Tracing genomic variations in two highly virulent Yersinia enterocolitica strains with unequal ability to compete for host colonization

    Directory of Open Access Journals (Sweden)

    Garzetti Debora

    2012-09-01

    Full Text Available Abstract Background Yersinia enterocolitica is a gastrointestinal foodborne pathogen found worldwide and which especially affects infants and young children. While different bioserotypes have been associated with varying pathogenicity, research on Y. enterocolitica is mainly conducted on the highly virulent mouse-lethal strains of biotype 1B and serotype O:8. We demonstrate here that two Y. enterocolitica bioserotype 1B/O:8 strains, 8081 and WA-314, display different virulence and fitness properties in a mouse model. In vivo co-infection experiments revealed that strain WA-314 overcomes strain 8081 in the colonization of spleen and liver. To trace the reasons of this incongruity, we present here the first high-quality sequence of the whole genome of strain WA-314 and compare it to the published genome of strain 8081. Results Regions previously accepted as unique to strain 8081, like the YAPI and YGI-3 genomic islands, are absent from strain WA-314, confirming their strain-specificity. On the other hand, some fitness- and bacterial competition-associated features, such as a putative colicin cluster and a xenobiotic-acyltransferase-encoding gene, are unique to strain WA-314. Additional acquisitions of strain WA-314 are seven prophage-like regions. One of these prophages, the 28-kb P4-like prophage YWA-4, encodes a PilV-like protein that may be used for adhesion to and invasion of the intestinal cells. Furthermore, a putative autotransporter and two type 1 fimbrial proteins of strain WA-314 show a sequence similarity Y. enterocolitica strains 8081 and WA-314 and thus the different efficiency of host colonization. Further important differences were found in two pYV plasmid-encoded virulence factors, YopM and YscP. The impact of these differences on virulence is discussed. Conclusions Our study emphasizes that the virulence of pathogens can be increased, by acquiring new genes and/or improving the function of essential virulence proteins, resulting

  14. Tracing genomic variations in two highly virulent Yersinia enterocolitica strains with unequal ability to compete for host colonization

    Science.gov (United States)

    2012-01-01

    Background Yersinia enterocolitica is a gastrointestinal foodborne pathogen found worldwide and which especially affects infants and young children. While different bioserotypes have been associated with varying pathogenicity, research on Y. enterocolitica is mainly conducted on the highly virulent mouse-lethal strains of biotype 1B and serotype O:8. We demonstrate here that two Y. enterocolitica bioserotype 1B/O:8 strains, 8081 and WA-314, display different virulence and fitness properties in a mouse model. In vivo co-infection experiments revealed that strain WA-314 overcomes strain 8081 in the colonization of spleen and liver. To trace the reasons of this incongruity, we present here the first high-quality sequence of the whole genome of strain WA-314 and compare it to the published genome of strain 8081. Results Regions previously accepted as unique to strain 8081, like the YAPI and YGI-3 genomic islands, are absent from strain WA-314, confirming their strain-specificity. On the other hand, some fitness- and bacterial competition-associated features, such as a putative colicin cluster and a xenobiotic-acyltransferase-encoding gene, are unique to strain WA-314. Additional acquisitions of strain WA-314 are seven prophage-like regions. One of these prophages, the 28-kb P4-like prophage YWA-4, encodes a PilV-like protein that may be used for adhesion to and invasion of the intestinal cells. Furthermore, a putative autotransporter and two type 1 fimbrial proteins of strain WA-314 show a sequence similarity enterocolitica strains 8081 and WA-314 and thus the different efficiency of host colonization. Further important differences were found in two pYV plasmid-encoded virulence factors, YopM and YscP. The impact of these differences on virulence is discussed. Conclusions Our study emphasizes that the virulence of pathogens can be increased, by acquiring new genes and/or improving the function of essential virulence proteins, resulting in permanently hyper-virulent

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

    Directory of Open Access Journals (Sweden)

    Muhammad A. Rasheed

    2017-05-01

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

  16. Virulence determinants of Pseudomonas syringae strains isolated from grasses in the context of a small type III effector repertoire

    DEFF Research Database (Denmark)

    Dudnik, Alexey; Dudler, Robert

    2014-01-01

    derivative that inhibits the eukaryotic proteasome. In strains colonizing dicotyledonous plants, the compound was demonstrated to suppress the salicylic-acid-dependent defense pathway. Here, we analyze virulence factors of three strains colonizing wheat (Triticum aestivum): P. syringae pathovar syringae (Psy...

  17. Relationship between oviposition, virulence gene expression and parasitism success in Cotesia typhae nov. sp. parasitoid strains.

    Science.gov (United States)

    Benoist, R; Chantre, C; Capdevielle-Dulac, C; Bodet, M; Mougel, F; Calatayud, P A; Dupas, S; Huguet, E; Jeannette, R; Obonyo, J; Odorico, C; Silvain, J F; Le Ru, B; Kaiser, L

    2017-12-01

    Studying mechanisms that drive host adaptation in parasitoids is crucial for the efficient use of parasitoids in biocontrol programs. Cotesia typhae nov. sp. (Fernández-Triana) (Hymenoptera: Braconidae) is a newly described parasitoid of the Mediterranean corn borer Sesamia nonagrioides (Lefebvre) (Lepidoptera: Noctuidae). Braconidae are known for their domesticated bracovirus, which is injected with eggs in the host larva to overcome its resistance. In this context, we compared reproductive success traits of four Kenyan strains of C. typhae on a French and a Kenyan populations of its host. Differences were found between the four strains and the two most contrasted ones were studied more thoroughly on the French host population. Parasitoid offspring size was correlated with parasitism success and the expression of bracovirus virulence genes (CrV1 and Cystatin) in the host larva after parasitism. Hybrids between these two parasitoid strains showed phenotype and gene expression profiles similar to the most successful parental strain, suggesting the involvement of dominant alleles in the reproductive traits. Ovary dissections revealed that the most successful strain injected more eggs in a single host larva than the less successful one, despite an equal initial ovocyte number in ovaries. It can be expected that the amount of viral particles increase with the number of eggs injected. The ability to bypass the resistance of the allopatric host may in consequence be related to the oviposition behaviour (eggs allocation). The influence of the number of injected eggs on parasitism success and on virulence gene expression was evaluated by oviposition interruption experiments.

  18. Pathophysiology of Escherichia coli ventilator-associated pneumonia: implication of highly virulent extraintestinal pathogenic strains.

    Science.gov (United States)

    Messika, Jonathan; Magdoud, Fatma; Clermont, Olivier; Margetis, Dimitri; Gaudry, Stéphane; Roux, Damien; Branger, Catherine; Dreyfuss, Didier; Denamur, Erick; Ricard, Jean-Damien

    2012-12-01

    To characterize Escherichia coli ventilator-associated pneumonia (VAP) in intensive care unit (ICU) patients by determining antibioresistance and genotypic characteristics of E. coli isolates responsible for VAP or lung colonization, by comparing them with their oropharyngeal and rectal counterparts and by assessing representative isolates' virulence in a pneumonia mouse model. Patients under mechanical ventilation for more than 72 h were screened for simultaneous presence of E. coli in rectal, oropharyngeal, and respiratory samples (colonization or VAP). If present, E. coli isolates were characterized by antimicrobial susceptibility, phylogenetic grouping, and virulence factor (VF) gene content determination. BALB/c mice were challenged intranasally with 3.6 × 10(8) colony-forming units (CFU) of patients' E. coli isolates. Multisite E. coli colonization was observed in 19 % of patients (25 patients, 12 with E. coli VAP). One hundred fifteen distinct E. coli isolates were analyzed. B2 phylogenetic group was predominant, with high VF gene content and low antimicrobial resistance. Antimicrobial resistance diversity was observed in four patients with VAP. E. coli isolates from VAP patients were more frequently B2 isolates, with significantly greater VF gene content than lung colonization isolates. Among screened VF genes, iroN and sfa appeared important for lung infection. A very strong correlation (R (2) = 0.99) was found between VF gene content and mortality in the mouse model. This is the first study establishing antibioresistance and genotypic characteristics of E. coli isolates responsible for VAP in adult ICU patients. These isolates are highly virulent specific extraintestinal pathogenic E. coli strains expressing virulence factors, representing potential targets for new therapies.

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

    Directory of Open Access Journals (Sweden)

    Hatice Türk Dağı

    2015-06-01

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

  20. Staphylococcus aureus and Staphylococcus epidermidis Virulence Strains as Causative Agents of Persistent Infections in Breast Implants.

    Directory of Open Access Journals (Sweden)

    Daniela Chessa

    Full Text Available Staphylococcus epidermidis and Staphylococcus aureus are currently considered two of the most important pathogens in nosocomial infections associated with catheters and other medical implants and are also the main contaminants of medical instruments. However because these species of Staphylococcus are part of the normal bacterial flora of human skin and mucosal surfaces, it is difficult to discern when a microbial isolate is the cause of infection or is detected on samples as a consequence of contamination. Rapid identification of invasive strains of Staphylococcus infections is crucial for correctly diagnosing and treating infections. The aim of the present study was to identify specific genes to distinguish between invasive and contaminating S. epidermidis and S. aureus strains isolated on medical devices; the majority of our samples were collected from breast prostheses. As a first step, we compared the adhesion ability of these samples with their efficacy in forming biofilms; second, we explored whether it is possible to determine if isolated pathogens were more virulent compared with international controls. In addition, this work may provide additional information on these pathogens, which are traditionally considered harmful bacteria in humans, and may increase our knowledge of virulence factors for these types of infections.

  1. Yersinia enterocolitica YopH-Deficient Strain Activates Neutrophil Recruitment to Peyer's Patches and Promotes Clearance of the Virulent Strain.

    Science.gov (United States)

    Dave, Mabel N; Silva, Juan E; Eliçabe, Ricardo J; Jeréz, María B; Filippa, Verónica P; Gorlino, Carolina V; Autenrieth, Stella; Autenrieth, Ingo B; Di Genaro, María S

    2016-11-01

    Yersinia enterocolitica evades the immune response by injecting Yersinia outer proteins (Yops) into the cytosol of host cells. YopH is a tyrosine phosphatase critical for Yersinia virulence. However, the mucosal immune mechanisms subverted by YopH during in vivo orogastric infection with Y. enterocolitica remain elusive. The results of this study revealed neutrophil recruitment to Peyer's patches (PP) after infection with a YopH-deficient mutant strain (Y. enterocolitica ΔyopH). While the Y. enterocolitica wild-type (WT) strain in PP induced the major neutrophil chemoattractant CXCL1 mRNA and protein levels, infection with the Y. enterocolitica ΔyopH mutant strain exhibited a higher expression of the CXCL1 receptor, CXCR2, in blood neutrophils, leading to efficient neutrophil recruitment to the PP. In contrast, migration of neutrophils into PP was impaired upon infection with Y. enterocolitica WT strain. In vitro infection of blood neutrophils revealed the involvement of YopH in CXCR2 expression. Depletion of neutrophils during Y. enterocolitica ΔyopH infection raised the bacterial load in PP. Moreover, the clearance of WT Y. enterocolitica was improved when an equal mixture of Y. enterocolitica WT and Y. enterocolitica ΔyopH strains was used in infecting the mice. This study indicates that Y. enterocolitica prevents early neutrophil recruitment in the intestine and that the effector protein YopH plays an important role in the immune evasion mechanism. The findings highlight the potential use of the Y. enterocolitica YopH-deficient strain as an oral vaccine carrier. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  2. Genotypes and virulence characteristics of Shiga toxin-producing Escherichia coli O104 strains from different origins and sources.

    Science.gov (United States)

    Miko, Angelika; Delannoy, Sabine; Fach, Patrick; Strockbine, Nancy A; Lindstedt, Björn Arne; Mariani-Kurkdjian, Patricia; Reetz, Jochen; Beutin, Lothar

    2013-12-01

    Sixty-two Escherichia coli strains carrying the wzxO104-gene from different sources, origins and time periods were analyzed for their serotypes, virulence genes and compared for genomic similarity by pulsed-field gel-electrophoresis (PFGE). The O104 antigen was present in 55 strains and the structurally and genetically related capsular antigen K9 in five strains. The presence of 49 genes associated with enteropathogenic E. coli (EPEC), enteroaggregative E. coli (EAEC) and enterohemorrhagic E. coli (EHEC) was investigated. Fifty-four strains of serotypes O104:H2 (n=1), O104:H4 (n=37), O104:H7 (n=5) and O104:H21 (n=11) produced Shiga-toxins (Stx). Among STEC O104, a close association between serotype, virulence gene profile and genomic similarity was found. EAEC virulence genes were only present in STEC O104:H4 strains. EHEC-O157 plasmid-encoded genes were only found in STEC O104:H2, O104:H7 and O104:H21 strains. None of the 62 O104 or K9 strains carried an eae-gene involved in the attaching and effacing phenotype. The 38 O104:H4 strains formed a single PFGE-cluster (>83.7% similarity). Thirty-one of these strains were from the European O104:H4 outbreak in 2011. The outbreak strains and older O104:H4 strains from Germany (2001), Georgia and France (2009) clustered together at>86.2% similarity. O104:H4 strains isolated between 2001 and 2009 differed for some plasmid-encoded virulence genes compared to the outbreak strains from 2011. STEC O104:H21 and STEC O104:H7 strains isolated in the U.S. and in Europe showed characteristic differences in their Stx-types, virulence gene and PFGE profiles indicating that these have evolved separately. E. coli K9 strains were not associated with virulence and were heterogeneous for their serotypes and PFGE profiles. Copyright © 2013 Elsevier GmbH. All rights reserved.

  3. Small RNA pyrosequencing in the protozoan parasite Entamoeba histolytica reveals strain-specific small RNAs that target virulence genes

    Science.gov (United States)

    2013-01-01

    Background Small RNA mediated gene silencing is a well-conserved regulatory pathway. In the parasite Entamoeba histolytica an endogenous RNAi pathway exists, however, the depth and diversity of the small RNA population remains unknown. Results To characterize the small RNA population that associates with E. histolytica Argonaute-2 (EhAGO2-2), we immunoprecipitated small RNAs that associate with it and performed one full pyrosequencing run. Data analysis revealed new features of the 27nt small RNAs including the 5′-G predominance, distinct small RNA distribution patterns on protein coding genes, small RNAs mapping to both introns and exon-exon junctions, and small RNA targeted genes that are clustered particularly in sections of genome duplication. Characterization of genomic loci to which both sense and antisense small RNAs mapped showed that both sets of small RNAs have 5′-polyphosphate termini; strand-specific RT-PCR detected transcripts in both directions at these loci suggesting that both transcripts may serve as template for small RNA generation. In order to determine whether small RNA abundance patterns account for strain-specific gene expression profiles of E. histolytica virulent and non-virulent strains, we sequenced small RNAs from a non-virulent strain and found that small RNAs mapped to genes in a manner consistent with their regulation of strain-specific virulence genes. Conclusions We provided a full spectrum analysis for E. histolytica AGO2-2 associated 27nt small RNAs. Additionally, comparative analysis of small RNA populations from virulent and non-virulent amebic strains indicates that small RNA populations may regulate virulence genes. PMID:23347563

  4. Evaluation of CSFV Antibody ELISAs for the differentiation of infected from vacci-nated animals

    DEFF Research Database (Denmark)

    Schroeder, Sabine; Blome, Sandra; Koenen, Frank

    of vaccinated from infected animals (DIVA) is not possible. Newly developed modified live marker vaccines allow a DIVA strategy based on the use of enzyme linked immunosorbent assay (ELISA) tests. The aim of this study was to evaluate CSF virus (CSFV) Antibody ELISAs, com-mercially available in Europe......, for their diagnostic sensitivity as well as for their potential in differentiating between infected and marker vaccinated animals. Two newly available ELISAs were included into the tests, the Priocheck® CSFV Erns ELISA, a special DIVA test, and the LDL Pigtype® CSFV Antibody ELISA. An inter-laboratory comparison test...... with four EU national CSF reference labora-tories and one EU reference laboratory participating was organized. Seven differ-ent CSFV antibody ELISA test kits, targeting distinct antibodies (against E2, Erns, NS3) were provided to the participating laboratories together with a set of 41 samples. This set...

  5. Immunization of sheep against a virulent strain of Schistosoma mattheei using a strain of S. mattheei attenuated by hamster passage.

    Science.gov (United States)

    Dargie, J D; Berry, C I; Holmes, P H; Reid, J F; Breeze, R; Taylor, M G; James, E R; Nelson, G S

    1977-01-01

    We have previously described the characteristics of a relatively non-pathogenic laboratory strain of S. mattheei, attenuation of which was apparently caused by passage in hamsters. We now show that chronic infection with this avirulent strain largely protects sheep from the manifestations of acute schistosomiasis when challenged with a virulent strain of S. mattheei. Four sheep were each infected with 10 000 cercariae of the avirulent strain and, together with four wormfree sheep, challenged 63 weeks later with 10 000 S. mattheei cercariae of a pathogenic strain. Four more sheep acted as uninfected controls. Following challenge, the animals were weighed and bled weekly for PCV and serum protein determinations, and egg counts were carried out fortnightly on faeces taken from the rectum. Red cell and albumin turnover were monitored for two weeks immediately before challenge and for a similar period before necropsy, when the adult worms were recovered by perfusion and tissues sampled for histopathology and egg counting. The unvaccinated sheep developed severe disease 6-12 weeks after exposure characterised by marked anaemia, hypoalbuminaemia and hyper-gamma globulinaemia coinciding with the passage of blood-stained faeces and progressive inappetence. In the vaccinated sheep, there was an even earlier rise in gamma globulins, but the other clinico-pathological changes were generally slower to devleop and much milder in severity. The parasitological data showed that although this was partly due to a reduction in the establishment of the challenge worm population the main factor was probably a reduction in the fecundity of these worms.

  6. Systematic analysis of viral genes responsible for differential virulence between American and Australian West Nile virus strains.

    Science.gov (United States)

    Setoh, Yin Xiang; Prow, Natalie A; Rawle, Daniel J; Tan, Cindy Si En; Edmonds, Judith H; Hall, Roy A; Khromykh, Alexander A

    2015-06-01

    A variant Australian West Nile virus (WNV) strain, WNVNSW2011, emerged in 2011 causing an unprecedented outbreak of encephalitis in horses in south-eastern Australia. However, no human cases associated with this strain have yet been reported. Studies using mouse models for WNV pathogenesis showed that WNVNSW2011 was less virulent than the human-pathogenic American strain of WNV, New York 99 (WNVNY99). To identify viral genes and mutations responsible for the difference in virulence between WNVNSW2011 and WNVNY99 strains, we constructed chimeric viruses with substitution of large genomic regions coding for the structural genes, non-structural genes and untranslated regions, as well as seven individual non-structural gene chimeras, using a modified circular polymerase extension cloning method. Our results showed that the complete non-structural region of WNVNSW2011, when substituted with that of WNVNY99, significantly enhanced viral replication and the ability to suppress type I IFN response in cells, resulting in higher virulence in mice. Analysis of the individual non-structural gene chimeras showed a predominant contribution of WNVNY99 NS3 to increased virus replication and evasion of IFN response in cells, and to virulence in mice. Other WNVNY99 non-structural proteins (NS2A, NS4B and NS5) were shown to contribute to the modulation of IFN response. Thus a combination of non-structural proteins, likely NS2A, NS3, NS4B and NS5, is primarily responsible for the difference in virulence between WNVNSW2011 and WNVNY99 strains, and accumulative mutations within these proteins would likely be required for the Australian WNVNSW2011 strain to become significantly more virulent. © 2015 The Authors.

  7. Effects of Bacillus thuringiensis strains virulent to Varroa destructor on larvae and adults of Apis mellifera.

    Science.gov (United States)

    Alquisira-Ramírez, Eva Vianey; Peña-Chora, Guadalupe; Hernández-Velázquez, Víctor Manuel; Alvear-García, Andrés; Arenas-Sosa, Iván; Suarez-Rodríguez, Ramón

    2017-08-01

    The sublethal effects of two strains of Bacillus thuringiensis, which were virulent in vitro to Varroa destructor, were measured on Apis mellifera. The effects of five concentrations of total protein (1, 5, 25, 50 and 100μg/mL) from the EA3 and EA26.1 strains on larval and adult honey bees were evaluated for two and seven days under laboratory conditions. Based on the concentrations evaluated, total protein from the two strains did not affect the development of larvae, the syrup consumption, locomotor activity or proboscis extension response of adults. These same parameters were also tested for the effects of three concentrations (1, 10 and 15μg/kg) of cypermethrin as a positive control. Although no significant differences were observed after two days of treatment with cypermethrin, a dose-response relationship in syrup consumption and locomotor activity was observed. A significant reduction in the proboscis extension response of the bees treated with cypermethrin was also observed. Therefore, in contrast to cypermethrin, our results indicate that the EA3 and EA26.1 strains of B. thuringiensis can be used in beehives to control V. destructor and reduce the negative effects of this mite on colonies without adverse effects on the larvae and adults of A. mellifera. Additionally, the overuse of synthetic miticides, which produce both lethal and sublethal effects on bees, can be reduced. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. 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.

  9. Virion polypeptide heterogeneity among virulent and avirulent strains of eastern equine encephalitis (EEE) virus.

    Science.gov (United States)

    Walder, R; Rosato, R R; Eddy, G A

    1981-01-01

    Comparative analysis of structural virion polypeptides of 24 selected EEE virus strains, representing North and South American types, was performed by one-dimensional discontinuous sodium dodecyl sulfate (SDS)-polyacrylamide-gel electrophoresis (PAGE). The structural proteins of different EEE virus isolates, resolved by this method, exhibited mol.wts. values in the range of 57-60 X 10(3) for (E-1), 51-54 X 10(3) for (E-2) and 35-38 X 10(3) daltons for the core (NP) nucleocapsid. The exception was the South American human lethal virus, TRVL-89287 strain, which was shown to possess only a single envelope glycoprotein. The high molecular weight envelope (E-1) glycoprotein species was absent or co-migrated adjacent to the smaller envelope (E-2) glycoprotein. Results indicated similarities in the core (NP) proteins, however greater variability in the envelope (E-/ and/or E-2) glycoproteins. Based on these variations seven distinct profiles could be observed among the EEE virus strain studied. The classification based on the patterns of structural polypeptides obtained by SDS-PAGE of these strains does not correlate well with any other previously reported in vitro characteristics (antigenic subtypes, HTP elution profiles) nor with the in vivo virulence markers.

  10. Antimicrobial resistance and virulence gene profiles in P. multocida strains isolated from cats

    Directory of Open Access Journals (Sweden)

    Thais Sebastiana Porfida Ferreira

    2015-03-01

    Full Text Available Cats are often described as carriers of Pasteurella multocida in their oral microbiota. This agent is thought to cause pneumonia, conjunctivitis, rhinitis, gingivostomatitis, abscess and osteonecrosis in cats. Human infection with P. multocida has been described in several cases affecting cat owners or after cat bites. In Brazil, the cat population is approximately 21 million animals and is increasing, but there are no studies of the presence of P. multocida in the feline population or of human cases of infection associated with cats. In this study, one hundred and ninety-one healthy cats from owners and shelters in São Paulo State, Brazil, were evaluated for the presence of P. multocida in their oral cavities. Twenty animals were positive for P. multocida, and forty-one strains were selected and characterized by means of biochemical tests and PCR. The P. multocida strains were tested for capsular type, virulence genes and resistance profile. A total of 75.6% (31/41 of isolates belonged to capsular type A, and 24.4% (10/41 of the isolates were untypeable. None of the strains harboured toxA, tbpA or pfhA genes. The frequencies of the other genes tested were variable, and the data generated were used to build a dendrogram showing the relatedness of strains, which were clustered according to origin. The most common resistance profile observed was against sulfizoxazole and trimethoprim-sulphamethoxazole.

  11. Virulence genotype of Pasteurella multocida strains isolated from different hosts with various disease status.

    Science.gov (United States)

    Ewers, Christa; Lübke-Becker, Antina; Bethe, Astrid; Kiebling, Sabine; Filter, Matthias; Wieler, Lothar H

    2006-05-31

    To learn more about the molecular biology of Pasteurella multocida 289 strains isolated from various clinically healthy and diseased hosts were examined for capsule biosynthesis genes (capA, B, D, E, and F) and 14 virulence associated genes by PCR and DNA-DNA-hybridization. As expected, capsule type A strains were highly adapted to bovines (92.3%) and poultry (85.7%) while we mainly found capA (34.9%)- and capD (58.1%)-positive strains in swine. A noticeable amount of capD-positive strains also originated from small ruminants (34.9%) and capF was detected in wild type strains from diseased cattle (2.2%) and cats (7.4%). None of the isolates harboured capE, while capB was exclusively found in all strains from buffaloes. Nearly all isolates showed a combination of genes encoding outer membrane proteins, colonization factors, iron aquisition factors and superoxid-dismutases without any clue for host specificity. In contrast, the transferrin binding protein encoding gene tbpA (31.5%) was limited to ruminant strains and only 37.0% of all P. multocida strains harboured pfhA, coding for a filamentous hemagglutinin, supposed to be a putative adhesion- und serum resistance factor. PfhA revealed a strong positive association to the outcome of disease in bovine hosts and in combination with toxA to that in swine. The dermonecrotoxin encoding toxA, present in 12.5% of all strains, was detected in isolates from swine, small ruminants, cattle, and poultry. A significant association to the disease status, however, was only existent in swine, although with 66.7% we found a notably high prevalence of the toxin gene among strains from small ruminants. The genes toxA, tbpA and pfhA as well as capsule biosynthesis genes are supposed to be important epidemiological marker genes for characterizing P. multocida field strains.

  12. Characterization of Yersinia enterocolitica strains potentially virulent for humans and animals in river water.

    Science.gov (United States)

    Terech-Majewska, E; Pajdak, J; Platt-Samoraj, A; Szczerba-Turek, A; Bancerz-Kisiel, A; Grabowska, K

    2016-08-01

    The aim of this study was to isolate and identify potentially pathogenic strains of Yersinia enterocolitica in water samples collected from the upstream section of the Drwęca River in Poland. Thirty-nine water samples were collected. Strains were isolated, identified with the use of the API(®) 20E test kit (Biomerieux, Marcy l'Etoile, France) at 37°C, serotyped and subjected to a molecular analysis. Multiplex PCR was carried out to amplify three virulence genes: ail, ystA and ystB. Fragments of ail and ystA genes were not identified in the genetic material of the analysed strains. The ystB gene was identified in four strains. Yersinia enterocolitica strains of biotype 1A, which contain the ystB gene, may cause gastrointestinal problems. In our study, Y. enterocolitica strains of biotype 1A/ystB with serotypes 0 : 3, 0 : 5 and 0 : 8 were identified in samples collected from the Drwęca River which flows through the areas protected by Natura 2000, one of the largest networks of nature conservation areas in the European Union. The presence of Y. enterocolitica in the Drwęca River indicates that the analysed bacteria colonize natural water bodies. Most research focuses on food or sewage as a source of Y. enterocolitica infections. Little is known about the occurrence of this pathogen in natural waters. Our results show that natural waters are also a potential threat to human and animal health. © 2016 The Society for Applied Microbiology.

  13. Differential virulence and tsetse fly transmissibility of Trypanosoma congolense and Trypanosoma brucei strains

    Directory of Open Access Journals (Sweden)

    Purity K. Gitonga

    2017-01-01

    Full Text Available African animal trypanosomiasis causes significant economic losses in sub-Saharan African countries because of livestock mortalities and reduced productivity. Trypanosomes, the causative agents, are transmitted by tsetse flies (Glossina spp.. In the current study, we compared and contrasted the virulence characteristics of five Trypanosoma congolense and Trypanosoma brucei isolates using groups of Swiss white mice (n = 6. We further determined the vectorial capacity of Glossina pallidipes, for each of the trypanosome isolates. Results showed that the overall pre-patent (PP periods were 8.4 ± 0.9 (range, 4–11 and 4.5 ± 0.2 (range, 4–6 for T. congolense and T. brucei isolates, respectively (p < 0.01. Despite the longer mean PP, T. congolense–infected mice exhibited a significantly (p < 0.05 shorter survival time than T. brucei–infected mice, indicating greater virulence. Differences were also noted among the individual isolates with T. congolense KETRI 2909 causing the most acute infection of the entire group with a mean ± standard error survival time of 9 ± 2.1 days. Survival time of infected tsetse flies and the proportion with mature infections at 30 days post-exposure to the infective blood meals varied among isolates, with subacute infection–causing T. congolense EATRO 1829 and chronic infection–causing T. brucei EATRO 2267 isolates showing the highest mature infection rates of 38.5% and 23.1%, respectively. Therefore, our study provides further evidence of occurrence of differences in virulence and transmissibility of eastern African trypanosome strains and has identified two, T. congolense EATRO 1829 and T. brucei EATRO 2267, as suitable for tsetse infectivity and transmissibility experiments.

  14. Brucella abortus RB51 induces protection in mice orally infected with the virulent strain B. abortus 2308.

    Science.gov (United States)

    Pasquali, Paolo; Rosanna, Adone; Pistoia, Claudia; Petrucci, Paola; Ciuchini, Franco

    2003-05-01

    Brucellae are gram-negative, facultative intracellular bacteria which are one of the most common causes of abortion in animals. In addition, they are the source of a severe zoonosis. In this trial, we evaluated the effect of oral inoculation of Brucella abortus RB51 in mice against a challenge infection with B. abortus 2308. First, we showed that a gastric acid neutralization prior to the oral inoculation contributed to a more homogeneous and consistent infection with both vaccine strain B. abortus RB51 and virulent strain B. abortus 2308. Successively, we assessed the clearance and the immune response following an oral infection with B. abortus RB51. Oral inoculation gave a mild infection which was cleared 42 days after infection, and it induced a delayed humoral and cell-mediated immune response. Finally, we immunized mice by oral inoculation with B. abortus RB51, and we challenged them with the virulent strain B. abortus 2308 by an oral or intraperitoneal route 42 days after vaccination. Oral inoculation of B. abortus RB51 was able to give protection to mice infected with the virulent strain B. abortus 2308 by the oral route but not to mice infected intraperitoneally. Our results indicate that oral inoculation of mice with B. abortus RB51 is able to give a protective immunity against an oral infection with virulent strains, and this protection seems to rely on an immune response at the mucosal level.

  15. Differential interactions of virulent and non-virulent H. parasuis strains with naïve or swine influenza virus pre-infected dendritic cells

    Directory of Open Access Journals (Sweden)

    Mussá Tufária

    2012-11-01

    Full Text Available Abstract Pigs possess a microbiota in the upper respiratory tract that includes Haemophilus parasuis. Pigs are also considered the reservoir of influenza viruses and infection with this virus commonly results in increased impact of bacterial infections, including those by H. parasuis. However, the mechanisms involved in host innate responses towards H. parasuis and their implications in a co-infection with influenza virus are unknown. Therefore, the ability of a non-virulent H. parasuis serovar 3 (SW114 and a virulent serovar 5 (Nagasaki strains to interact with porcine bone marrow dendritic cells (poBMDC and their modulation in a co-infection with swine influenza virus (SwIV H3N2 was examined. At 1 hour post infection (hpi, SW114 interaction with poBMDC was higher than that of Nagasaki, while at 8 hpi both strains showed similar levels of interaction. The co-infection with H3N2 SwIV and either SW114 or Nagasaki induced higher levels of IL-1β, TNF-α, IL-6, IL-12 and IL-10 compared to mock or H3N2 SwIV infection alone. Moreover, IL-12 and IFN-α secretion differentially increased in cells co-infected with H3N2 SwIV and Nagasaki. These results pave the way for understanding the differences in the interaction of non-virulent and virulent strains of H. parasuis with the swine immune system and their modulation in a viral co-infection.

  16. Draft Genome Sequence of a Virulent Strain of Pasteurella Multocida Isolated From Alpaca.

    Science.gov (United States)

    Hurtado, Raquel Enma; Aburjaile, Flavia; Mariano, Diego; Canário, Marcus Vinicius; Benevides, Leandro; Fernandez, Daniel Antonio; Allasi, Nataly Olivia; Rimac, Rocio; Juscamayta, Julio Eduardo; Maximiliano, Jorge Enrique; Rosadio, Raul Hector; Azevedo, Vasco; Maturrano, Lenin

    2017-01-01

    Pasteurella multocida is one of the most frequently isolated bacteria in acute pneumonia cases, being responsible for high mortality rates in Peruvian young alpacas, with consequent social and economic costs. Here we report the genome sequence of P. multocida strain UNMSM, isolated from the lung of an alpaca diagnosed with pneumonia, in Peru. The genome consists of 2,439,814 base pairs assembled into 82 contigs and 2,252 protein encoding genes, revealing the presence of known virulence-associated genes (ompH, ompA, tonB, tbpA, nanA, nanB, nanH, sodA, sodC, plpB and toxA). Further analysis could provide insights about bacterial pathogenesis and control strategies of this disease in Peruvian alpacas.

  17. Pathologic changes in pigeons infected with a virulent Trichomonas gallinae strain (Eiberg).

    Science.gov (United States)

    Narcisi, E M; Sevoian, M; Honigberg, B M

    1991-01-01

    Trichomonas gallinae, Eiberg strain, is a virulent hepatotropic flagellate parasite of pigeons. The parasite initially infects the upper digestive tract, causing the formation of ulcers, which allow it to enter the circulatory system. The trichomonads later gain access to the liver, where they cause the formation of caseous lesions. Vascular congestion and perivascular cuffing in the liver were seen as early as 4 days postinfection (PI). By day 7 PI, a marked reduction in abdominal fat and hepatosplenomegaly was evident. Hepatocytes underwent fatty degeneration (seen by day 7 PI) before total necrosis set in. On day 8 PI, trichomonads could be found among the necrotic hepatocytes in caseous lesions. These lesions were delineated by a wall of leukocytes and occasional giant cells. Nonimmune pigeons died within 14 to 17 days PI of liver dysfunction. Other organs (kidney and genitalia) were also seen to undergo degeneration. These manifestations probably reflect the progression of liver dysfunction.

  18. Comparative Genomic Analysis of Lactococcus garvieae Strains Isolated from Different Sources Reveals Candidate Virulence Genes

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    Eiji Miyauchi

    2012-01-01

    Full Text Available Lactococcus garvieae is a major pathogen for fish. Two complete (ATCC 49156 and Lg2 and three draft (UNIUD074, 8831, and 21881 genome sequences of L. garvieae have recently been released. We here present the results of a comparative genomic analysis of these fish and human isolates of L. garvieae. The pangenome comprised 1,542 core and 1,378 dispensable genes. The sequenced L. garvieae strains shared most of the possible virulence genes, but the capsule gene cluster was found only in fish-pathogenic strain Lg2. The absence of the capsule gene cluster in other nonpathogenic strains isolated from mastitis and vegetable was also confirmed by PCR. The fish and human isolates of L. garvieae contained the specific two and four adhesin genes, respectively, indicating that these adhesion proteins may be involved in the host specificity differences of L. garvieae. The discoveries revealed by the pangenomic analysis may provide significant insights into the biology of L. garvieae.

  19. Comparative Genomic Analysis of Two Vibrio toranzoniae Strains with Different Virulence Capacity Reveals Clues on Its Pathogenicity for Fish.

    Science.gov (United States)

    Lasa, Aide; Gibas, Cynthia J; Romalde, Jesús L

    2017-01-01

    Vibrio toranzoniae is a Gram-negative bacterium of the Splendidus clade within the Vibrio genus. V. toranzoniae was first isolated from healthy clams in Galicia (Spain) but recently was also identified associated to disease outbreaks of red conger eel in Chile. Experimental challenges showed that the Chilean isolates were able to produce fish mortalities but not the strains isolated from clams. The aim of the present study was to determine the differences at the genomic level between the type strain of the species (CECT 7225(T)) and the strain R17, isolated from red conger eel in Chile, which could explain their different virulent capacity. The genome-based comparison showed high homology between both strains but differences were observed in certain gene clusters that include some virulence factors. Among these, we found that iron acquisition systems and capsule synthesis genes were the main differential features between both genomes that could explain the differences in the pathogenicity of the strains. Besides, the studied genomes presented genomic islands and toxins, and the R17 strain presented CRISPR sequences that are absent on the type strain. Taken together, this analysis provided important insights into virulence factors of V. toranzoniae that will lead to a better understanding of the pathogenic process.

  20. Differentiation of the virulence potential of Campylobacter jejuni strains by use of gene transcription analysis and a caco-2 assay

    DEFF Research Database (Denmark)

    Poli, Vanessa Fadanelli Schoenardie; Thorsen, Line; Olesen, Inger

    2012-01-01

    Campylobacter jejuni is the leading cause of bacterial diarrheal disease in humans, and contaminated poultry and poultry products are recognized as the main vehicle of infection. Despite the significance of C. jejuni as a foodborne pathogen, little is known about its response to stress, and......, especially, how its virulence is modulated under such conditions. The aim of this study was to assess the effect of temperature shift in a broth model system on virulence expression and cell survival of three different Campylobacter jejuni strains: two clinical (TB1048 and NCTC11168) and one chicken isolate...... properties were evaluated by analyzing transcriptions of the virulence genes cdtB, ciaB, cadF and the stress associated genes clpP, htrB using reverse transcription quantitative PCR (RT-qPCR) and by the ability of the C. jejuni strains to adhere to and invade Caco-2 cells. Similar cell survival and no growth...

  1. Ulcerogenic Helicobacter pylori strains isolated from children: a contribution to get insight into the virulence of the bacteria.

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    Inês Vitoriano

    Full Text Available Infection with Helicobacter pylori is the major cause for the development of peptic ulcer disease (PUD. In children, with no other etiology for the disease, this rare event occurs shortly after infection. In these young patients, habits of smoking, diet, consumption of alcohol and non-steroid anti-inflammatory drugs and stress, in addition to the genetic susceptibility of the patient, represent a minor influence. Accordingly, the virulence of the implicated H. pylori strain should play a crucial role in the development of PUD. Corroborating this, our in vitro infection assays comparing a pool of five H. pylori strains isolated from children with PUD to a pool of five other pediatric clinical isolates associated with non-ulcer dyspepsia (NUD showed the greater ability of PUD strains to induce a marked decrease in the viability of gastric cells and to cause severe damage in the cells cytoskeleton as well as an impairment in the production/secretion of mucins. To uncover virulence features, we compared the proteome of these two groups of H. pylori strains. Two-dimensional gel electrophoresis followed by mass-spectrometry allowed us to detect 27 differentially expressed proteins between them. In addition to the presence of genes encoding well established virulence factors, namely cagA, vacAs1, oipA "on" status, homB and jhp562 genes, the pediatric ulcerogenic strains shared a proteome profile characterized by changes in the abundance of: motility-associated proteins, accounting for higher motility; antioxidant proteins, which may confer increased resistance to inflammation; and enzymes involved in key steps in the metabolism of glucose, amino acids and urea, which may be advantageous to face fluctuations of nutrients. In conclusion, the enhanced virulence of the pediatric ulcerogenic H. pylori strains may result from a synergy between their natural ability to better adapt to the hostile human stomach and the expression of the established virulence

  2. Ulcerogenic Helicobacter pylori Strains Isolated from Children: A Contribution to Get Insight into the Virulence of the Bacteria

    Science.gov (United States)

    Vitoriano, Inês; Saraiva-Pava, Kathy D.; Rocha-Gonçalves, Alexandra; Santos, Andrea; Lopes, Ana I.; Oleastro, Mónica; Roxo-Rosa, Mónica

    2011-01-01

    Infection with Helicobacter pylori is the major cause for the development of peptic ulcer disease (PUD). In children, with no other etiology for the disease, this rare event occurs shortly after infection. In these young patients, habits of smoking, diet, consumption of alcohol and non-steroid anti-inflammatory drugs and stress, in addition to the genetic susceptibility of the patient, represent a minor influence. Accordingly, the virulence of the implicated H. pylori strain should play a crucial role in the development of PUD. Corroborating this, our in vitro infection assays comparing a pool of five H. pylori strains isolated from children with PUD to a pool of five other pediatric clinical isolates associated with non-ulcer dyspepsia (NUD) showed the greater ability of PUD strains to induce a marked decrease in the viability of gastric cells and to cause severe damage in the cells cytoskeleton as well as an impairment in the production/secretion of mucins. To uncover virulence features, we compared the proteome of these two groups of H. pylori strains. Two-dimensional gel electrophoresis followed by mass-spectrometry allowed us to detect 27 differentially expressed proteins between them. In addition to the presence of genes encoding well established virulence factors, namely cagA, vacAs1, oipA “on” status, homB and jhp562 genes, the pediatric ulcerogenic strains shared a proteome profile characterized by changes in the abundance of: motility-associated proteins, accounting for higher motility; antioxidant proteins, which may confer increased resistance to inflammation; and enzymes involved in key steps in the metabolism of glucose, amino acids and urea, which may be advantageous to face fluctuations of nutrients. In conclusion, the enhanced virulence of the pediatric ulcerogenic H. pylori strains may result from a synergy between their natural ability to better adapt to the hostile human stomach and the expression of the established virulence factors. PMID

  3. Production of cytolethal distending toxin and other virulence characteristics of Escherichia coli strains of serogroup O86

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    Ghilardi Ângela Cristina Rodrigues

    2001-01-01

    Full Text Available Genetic and phenotypic virulence markers of different categories of diarrhoeagenic Escherichia coli were investigated in 106 strains of enteropathogenic E. coli (EPEC serogroup O86. The most frequent serotype found was O86:H34 (86%. Strains of this serotype and the non motile ones behaved as EPEC i.e., carried eae, bfpA and EAF DNA sequences and presented localised adherence to HeLa cells. Serotypes O86:H2, O86:H6, O86:H10, O86:H18, O86:H27 and O86:H non determined, belonged to other categories. The majority of the strains of serotype O86:H34 and non motile strains produced cytolethal-distending toxin (CDT. The ribotyping analysis showed a correlation among ribotypes, virulence markers and serotypes, thus suggesting that CDT production might be a property associated with a universal clone represented by the O86:H34 serotype.

  4. Mortality and kidney histopathology of Chinook salmon Oncorhynchus tshawytscha exposed to virulent and attenuated Renibacterium salmoninarum strains

    Science.gov (United States)

    O'Farrell, Caroline L.; Elliott, Diane G.; Landolt, Marsha L.

    2001-01-01

    An isolate of Renibacterium salmoninarum (strain MT 239) exhibiting reduced virulence in rainbow trout Oncorhynchus mykiss was tested for its ability to cause bacterial kidney disease (BKD) in chinook salmon Oncorhynchus tshawytscha, a salmonid species more susceptible to BKD. Juvenile chinook salmon were exposed to either 33209, the American Type Culture Collection type strain of R. salmoninarum, or to MT 239, by an intraperitoneal injection of 1 x 10(3) or 1 x 10(6) bacteria fish(-1), or by a 24 h immersion in 1 x 10(5) or 1 x 10(7) bacteria ml(-1). For 22 wk fish were held in 12 degrees C water and monitored for mortality. Fish were sampled periodically for histological examination of kidney tissues. In contrast to fish exposed to the high dose of strain 33209 by either injection or immersion, none of the fish exposed to strain MT 239 by either route exhibited gross clinical signs or histopathological changes indicative of BKD. However, the MT 239 strain was detected by the direct fluorescent antibody technique in 4 fish that died up to 11 wk after the injection challenge and in 5 fish that died up to 20 wk after the immersion challenge. Viable MT 239 was isolated in culture from 3 fish that died up to 13 wk after the immersion challenge. Total mortality in groups injected with the high dose of strain MT 239 (12%) was also significantly lower (p < 0.05) than mortality in groups injected with strain 33209 (73 %). These data indicate that the attenuated virulence observed with MT 239 in rainbow trout also occurs in a salmonid species highly susceptible to BKD. The reasons for the attenuated virulence of MT 239 were not determined but may be related to the reduced levels of the putative virulence protein p57 associated with this strain.

  5. Comparative Transcriptome Profiling Reveals Different Expression Patterns in Xanthomonas oryzae pv. oryzae Strains with Putative Virulence-Relevant Genes

    Science.gov (United States)

    Zhang, Fan; Du, Zhenglin; Huang, Liyu; Cruz, Casiana Vera; Zhou, Yongli; Li, Zhikang

    2013-01-01

    Xanthomonas oryzae pv. oryzae (Xoo) is the causal agent of rice bacterial blight, which is a major rice disease in tropical Asian countries. An attempt has been made to investigate gene expression patterns of three Xoo strains on the minimal medium XOM2, PXO99 (P6) and PXO86 (P2) from the Philippines, and GD1358 (C5) from China, which exhibited different virulence in 30 rice varieties, with putative virulence factors using deep sequencing. In total, 4,781 transcripts were identified in this study, and 1,151 and 3,076 genes were differentially expressed when P6 was compared with P2 and with C5, respectively. Our results indicated that Xoo strains from different regions exhibited distinctly different expression patterns of putative virulence-relevant genes. Interestingly, 40 and 44 genes involved in chemotaxis and motility exhibited higher transcript alterations in C5 compared with P6 and P2, respectively. Most other genes associated with virulence, including exopolysaccharide (EPS) synthesis, Hrp genes and type III effectors, including Xanthomonas outer protein (Xop) effectors and transcription activator-like (TAL) effectors, were down-regulated in C5 compared with P6 and P2. The data were confirmed by real-time quantitative RT-PCR, tests of bacterial motility, and enzyme activity analysis of EPS and xylanase. These results highlight the complexity of Xoo and offer new avenues for improving our understanding of Xoo-rice interactions and the evolution of Xoo virulence. PMID:23734193

  6. Genome Plasticity and Polymorphisms in Critical Genes Correlate with Increased Virulence of Dutch Outbreak-Related Coxiella burnetii Strains

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    Runa Kuley

    2017-08-01

    Full Text Available Coxiella burnetii is an obligate intracellular bacterium and the etiological agent of Q fever. During 2007–2010 the largest Q fever outbreak ever reported occurred in The Netherlands. It is anticipated that strains from this outbreak demonstrated an increased zoonotic potential as more than 40,000 individuals were assumed to be infected. The acquisition of novel genetic factors by these C. burnetii outbreak strains, such as virulence-related genes, has frequently been proposed and discussed, but is not proved yet. In the present study, the whole genome sequence of several Dutch strains (CbNL01 and CbNL12 genotypes, a few additionally selected strains from different geographical locations and publicly available genome sequences were used for a comparative bioinformatics approach. The study focuses on the identification of specific genetic differences in the outbreak related CbNL01 strains compared to other C. burnetii strains. In this approach we investigated the phylogenetic relationship and genomic aspects of virulence and host-specificity. Phylogenetic clustering of whole genome sequences showed a genotype-specific clustering that correlated with the clustering observed using Multiple Locus Variable-number Tandem Repeat Analysis (MLVA. Ortholog analysis on predicted genes and single nucleotide polymorphism (SNP analysis of complete genome sequences demonstrated the presence of genotype-specific gene contents and SNP variations in C. burnetii strains. It also demonstrated that the currently used MLVA genotyping methods are highly discriminatory for the investigated outbreak strains. In the fully reconstructed genome sequence of the Dutch outbreak NL3262 strain of the CbNL01 genotype, a relatively large number of transposon-linked genes were identified as compared to the other published complete genome sequences of C. burnetii. Additionally, large numbers of SNPs in its membrane proteins and predicted virulence-associated genes were identified

  7. Genome Plasticity and Polymorphisms in Critical Genes Correlate with Increased Virulence of Dutch Outbreak-Related Coxiella burnetii Strains

    Science.gov (United States)

    Kuley, Runa; Kuijt, Eric; Smits, Mari A.; Roest, Hendrik I. J.; Smith, Hilde E.; Bossers, Alex

    2017-01-01

    Coxiella burnetii is an obligate intracellular bacterium and the etiological agent of Q fever. During 2007–2010 the largest Q fever outbreak ever reported occurred in The Netherlands. It is anticipated that strains from this outbreak demonstrated an increased zoonotic potential as more than 40,000 individuals were assumed to be infected. The acquisition of novel genetic factors by these C. burnetii outbreak strains, such as virulence-related genes, has frequently been proposed and discussed, but is not proved yet. In the present study, the whole genome sequence of several Dutch strains (CbNL01 and CbNL12 genotypes), a few additionally selected strains from different geographical locations and publicly available genome sequences were used for a comparative bioinformatics approach. The study focuses on the identification of specific genetic differences in the outbreak related CbNL01 strains compared to other C. burnetii strains. In this approach we investigated the phylogenetic relationship and genomic aspects of virulence and host-specificity. Phylogenetic clustering of whole genome sequences showed a genotype-specific clustering that correlated with the clustering observed using Multiple Locus Variable-number Tandem Repeat Analysis (MLVA). Ortholog analysis on predicted genes and single nucleotide polymorphism (SNP) analysis of complete genome sequences demonstrated the presence of genotype-specific gene contents and SNP variations in C. burnetii strains. It also demonstrated that the currently used MLVA genotyping methods are highly discriminatory for the investigated outbreak strains. In the fully reconstructed genome sequence of the Dutch outbreak NL3262 strain of the CbNL01 genotype, a relatively large number of transposon-linked genes were identified as compared to the other published complete genome sequences of C. burnetii. Additionally, large numbers of SNPs in its membrane proteins and predicted virulence-associated genes were identified in all Dutch

  8. Virulence variation among strains of the emerging infectious fungus Batrachochytrium dendrobatidis (Bd) in multiple amphibian host species.

    Science.gov (United States)

    Dang, Trang D; Searle, Catherine L; Blaustein, Andrew R

    2017-05-11

    Emerging infectious diseases have been documented in numerous plant and animal populations. The infectious disease amphibian chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is associated with global amphibian population declines. While much Bd-amphibian research has centered on response variation in hosts, a paucity of information exists on how variation in the pathogen, such as strain differences, affects infection dynamics. To examine how different Bd strains may differentially impact multiple hosts, we conducted laboratory experiments to measure 2 infection outcomes, viz. host survival and pathogen load, in 3 amphibian host species (Pacific treefrog, western toad, and Cascades frog) after exposure to 3 different Bd strains (an additional fourth Bd strain was tested in toads only). Our results confirm that the infection response differs among host species. Western toads experienced significant mortality, but Pacific treefrogs and Cascades frogs did not. Interestingly, our experiment also captured strain-dependent virulence variation but only in 1 host species, the western toad. Increased mortality was observed in 2 of the 4 Bd strains tested in this host species. Toads were also the only host species found to have variable pathogen load dependent on strain type; individuals exposed to the Panama strain harbored significantly higher loads compared to all other strains. These findings underscore the dynamic nature of Bd infection, showing that virulence can vary contingent on host and strain type. We highlight the importance of both host- and pathogen-dependent factors in determining overall infection virulence and show the need for in vivo testing to fully assess pathogenicity.

  9. Comparative Genomic Characterization of the Highly Persistent and Potentially Virulent Cronobacter sakazakii ST83, CC65 Strain H322 and Other ST83 Strains

    Directory of Open Access Journals (Sweden)

    Hannah R. Chase

    2017-06-01

    Full Text Available Cronobacter (C. sakazakii is an opportunistic pathogen and has been associated with serious infections with high mortality rates predominantly in pre-term, low-birth weight and/or immune compromised neonates and infants. Infections have been epidemiologically linked to consumption of intrinsically and extrinsically contaminated lots of reconstituted powdered infant formula (PIF, thus contamination of such products is a challenging task for the PIF producing industry. We present the draft genome of C. sakazakii H322, a highly persistent sequence type (ST 83, clonal complex (CC 65, serotype O:7 strain obtained from a batch of non-released contaminated PIF product. The presence of this strain in the production environment was traced back more than 4 years. Whole genome sequencing (WGS of this strain together with four more ST83 strains (PIF production environment-associated confirmed a high degree of sequence homology among four of the five strains. Phylogenetic analysis using microarray (MA and WGS data showed that the ST83 strains were highly phylogenetically related and MA showed that between 5 and 38 genes differed from one another in these strains. All strains possessed the pESA3-like virulence plasmid and one strain possessed a pESA2-like plasmid. In addition, a pCS1-like plasmid was also found. In order to assess the potential in vivo pathogenicity of the ST83 strains, each strain was subjected to infection studies using the recently developed zebrafish embryo model. Our results showed a high (90–100% zebrafish mortality rate for all of these strains, suggesting a high risk for infections and illness in neonates potentially exposed to PIF contaminated with ST83 C. sakazakii strains. In summary, virulent ST83, CC65, serotype CsakO:7 strains, though rarely found intrinsically in PIF, can persist within a PIF manufacturing facility for years and potentially pose significant quality assurance challenges to the PIF manufacturing industry.

  10. Outbreak of Salmonella typhimurium infection traced to contaminated chocolate and caused by a strain lacking the 60-megadalton virulence plasmid.

    Science.gov (United States)

    Kapperud, G; Gustavsen, S; Hellesnes, I; Hansen, A H; Lassen, J; Hirn, J; Jahkola, M; Montenegro, M A; Helmuth, R

    1990-12-01

    We describe an outbreak of Salmonella typhimurium infection, caused by contaminated chocolate produced by one Norwegian company, which occurred in Norway and Finland in 1987. A total of 349 bacteriologically verified cases were recorded in Norway, and 12 cases were recorded in Finland. There was a predominance of young children among the patients (median age, 6 years), many of whom developed acute hemorrhagic diarrhea. The outbreak strain exhibited a rare phage lysis pattern and a characteristic plasmid profile lacking the 60-MDa virulence-associated plasmid. DNA hybridization failed to demonstrate any DNA sequence homology between the outbreak strain and the virulence plasmid. The outbreak strain was nonlethal for orally infected mice. The finding of only less than or equal to 10 S. typhimurium cells per 100 g of chocolate in about 90% of the positive samples obtained from retail outlets suggested that an inoculum of fewer than 10 organisms may have been sufficient to cause symptomatic disease.

  11. Comparative Proteomic Profiling of Ehrlichia ruminantium Pathogenic Strain and Its High-Passaged Attenuated Strain Reveals Virulence and Attenuation-Associated Proteins.

    Directory of Open Access Journals (Sweden)

    Isabel Marcelino

    Full Text Available The obligate intracellular bacterium Ehrlichia ruminantium (ER causes heartwater, a fatal tick-borne disease in livestock. In the field, ER strains present different levels of virulence, limiting vaccine efficacy, for which the molecular basis remains unknown. Moreover, there are no genetic tools currently available for ER manipulation, thus limiting the knowledge of the genes/proteins that are essential for ER pathogenesis and biology. As such, to identify proteins and/or mechanisms involved in ER virulence, we performed the first exhaustive comparative proteomic analysis between a virulent strain (ERGvir and its high-passaged attenuated strain (ERGatt. Despite their different behaviors in vivo and in vitro, our results from 1DE-nanoLC-MS/MS showed that ERGvir and ERGatt share 80% of their proteins; this core proteome includes chaperones, proteins involved in metabolism, protein-DNA-RNA biosynthesis and processing, and bacterial effectors. Conventional 2DE revealed that 85% of the identified proteins are proteoforms, suggesting that post-translational modifications (namely glycosylation are important in ER biology. Strain-specific proteins were also identified: while ERGatt has an increased number and overexpression of proteins involved in cell division, metabolism, transport and protein processing, ERGvir shows an overexpression of proteins and proteoforms (DIGE experiments involved in pathogenesis such as Lpd, AnkA, VirB9 and B10, providing molecular evidence for its increased virulence in vivo and in vitro. Overall, our work reveals that ERGvir and ERGatt proteomes are streamlined to fulfill their biological function (maximum virulence for ERGvir and replicative capacity for ERGatt, and we provide both pioneering data and novel insights into the pathogenesis of this obligate intracellular bacterium.

  12. Comparative Proteomic Profiling of Ehrlichia ruminantium Pathogenic Strain and Its High-Passaged Attenuated Strain Reveals Virulence and Attenuation-Associated Proteins

    Science.gov (United States)

    Marcelino, Isabel; Ventosa, Miguel; Pires, Elisabete; Müller, Markus; Lisacek, Frédérique; Lefrançois, Thierry; Vachiery, Nathalie; Coelho, Ana Varela

    2015-01-01

    The obligate intracellular bacterium Ehrlichia ruminantium (ER) causes heartwater, a fatal tick-borne disease in livestock. In the field, ER strains present different levels of virulence, limiting vaccine efficacy, for which the molecular basis remains unknown. Moreover, there are no genetic tools currently available for ER manipulation, thus limiting the knowledge of the genes/proteins that are essential for ER pathogenesis and biology. As such, to identify proteins and/or mechanisms involved in ER virulence, we performed the first exhaustive comparative proteomic analysis between a virulent strain (ERGvir) and its high-passaged attenuated strain (ERGatt). Despite their different behaviors in vivo and in vitro, our results from 1DE-nanoLC-MS/MS showed that ERGvir and ERGatt share 80% of their proteins; this core proteome includes chaperones, proteins involved in metabolism, protein-DNA-RNA biosynthesis and processing, and bacterial effectors. Conventional 2DE revealed that 85% of the identified proteins are proteoforms, suggesting that post-translational modifications (namely glycosylation) are important in ER biology. Strain-specific proteins were also identified: while ERGatt has an increased number and overexpression of proteins involved in cell division, metabolism, transport and protein processing, ERGvir shows an overexpression of proteins and proteoforms (DIGE experiments) involved in pathogenesis such as Lpd, AnkA, VirB9 and B10, providing molecular evidence for its increased virulence in vivo and in vitro. Overall, our work reveals that ERGvir and ERGatt proteomes are streamlined to fulfill their biological function (maximum virulence for ERGvir and replicative capacity for ERGatt), and we provide both pioneering data and novel insights into the pathogenesis of this obligate intracellular bacterium. PMID:26691135

  13. Evaluation of shedding, tissue burdens, and humoral immune response in goats after experimental challenge with the virulent Brucella melitensis strain 16M and the reduced virulence vaccine strain Rev. 1.

    Directory of Open Access Journals (Sweden)

    Jennifer L Higgins

    Full Text Available Brucella melitensis is the causative agent of brucellosis in small ruminants and is of considerable economic and public health importance in many countries worldwide. The control of disease in humans depends on the control of disease in livestock; however, few counties with endemic B. melitensis infection have been able to successfully eradicate this pathogen. This underscores the need for further research on the pathogenesis of both virulent and vaccine strains of B. melitensis in the small ruminant host. The aim of the present study was to characterize clinical effects, tissue colonization, shedding, and humoral immune response following B. melitensis infection in goats. Both virulent (16M and reduced virulence (Rev. 1 strains of B. melitensis were studied. Pregnant goats were infected at 11-14 weeks of gestation with 8 x 106 or 8 x 107 CFU of B. melitensis. Infection of goats with B. melitensis 16M resulted in an 86% abortion rate. This strain disseminated widely in pregnant does post-infection with none of the 15 sampled tissues spared from colonization. Importantly, we report the first isolation of B. melitensis from muscle tissue in ruminants. Pathogenesis of Rev. 1 infection was variable with two does showing minimal colonization and one doe exhibiting disease similar to that of animals infected with fully virulent 16M. Shedding of B. melitensis in milk occurred in all 16M- and Rev. 1- infected goats. In pregnant animals challenged with virulent B. melitensis, median time to seroconversion was 21 days; however, 2 animals did not seroconvert until after abortion.

  14. Identification of high- and low-virulent strains of Chlamydia pneumoniae by their characterization in a mouse pneumonia model.

    Science.gov (United States)

    Sommer, Kirsten; Njau, Florence; Wittkop, Ulrike; Thalmann, Jessica; Bartling, Gerda; Wagner, Annette; Klos, Andreas

    2009-03-01

    Contradicting reports exist about the pathogenicity of Chlamydia pneumoniae and the severity of the respiratory disease they cause. This study aimed to clarify, in mice, our hypothesis that marked differences in virulence of well-defined C. pneumoniae strains might exist for lung infections. C57BL/6J mice were intranasally infected with equal amounts of five different, identically prepared laboratory strains of C. pneumoniae. Based on the clinical score, weight, histopathological score, the granulocyte marker-enzyme myeloperoxidase, and the amount of Chlamydiae in the lung tissue, the C. pneumoniae isolates exhibited clear differences in overall growth characteristics or clearance, and pathological potential. Thus, we could identify chlamydial strains (Kajaani-K6 and CWL-029), where mice became seriously ill, as well as a relatively low-virulent isolate (TWAR-183). Cytokine profiles also varied drastically between the five strains in extent and kinetic. Our results indicate that C. pneumoniae isolates differ markedly with regard to their interaction with the host and their pathological potential. This might also be true for the infection in humans. Because the genomic diversity of C. pneumoniae is rather small, more subtle genomic deviations account most likely for the apparent functional differences. Our results will be useful to identify additional virulence factors in the future.

  15. In vivo evolution of tigecycline-non-susceptible Klebsiella pneumoniae strains in patients: relationship between virulence and resistance.

    Science.gov (United States)

    Lin, Yi-Tsung; Huang, Yi-Wei; Huang, Hsin-Hui; Yang, Tsuey-Ching; Wang, Fu-Der; Fung, Chang-Phone

    2016-11-01

    Tigecycline resistance among Klebsiella pneumoniae isolates has been increasingly reported. We aimed to investigate the relationship among in vivo acquisition of tigecycline resistance in K. pneumoniae clinical isolates, the underlying molecular mechanisms and bacterial virulence. Clinical isolates of K. pneumoniae from the same patient in a medical centre in Taiwan that were initially tigecycline-susceptible (TS) and then became tigecycline-non-susceptible (TNS) were identified. Clinical data were collected. All isolates were subjected to MIC determination by Etest, pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), virulence factor determination, and growth rate and mouse lethality studies. Quantitative RT-PCR was performed to analyse acrA, oqxA, ramA and rarA expressions. The presence of mutations in acrR, ramR, oqxR and rpsJ were analysed by DNA sequencing. Five isogenic paired isolates were determined by PFGE fingerprinting. TNS K. pneumoniae appeared after treatment with a variety of antibiotics among patients infected with TS K. pneumoniae. TNS K. pneumoniae isolates were associated with upregulation of RamA and/or RarA and the corresponding AcrAB and/or OqxAB efflux pump(s), respectively. Various mutations in negative regulatory genes (ramR and oqxR) accounted for overexpression of ramA and rarA, respectively. Three of the five paired isolates showed similar growth rates and virulence between TS and TNS isolates. Two TNS K. pneumoniae strains belonging to capsular types K1 and K20 retained their high virulence. In conclusion, some TNS K. pneumoniae strains derived from TS isolates did not compromise their virulence. Dissemination of these highly pathogenic and resistant strains would be of major concern in the future. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  16. Characterization of a highly virulent and antimicrobial-resistant Acinetobacter baumannii strain isolated from diseased chicks in China.

    Science.gov (United States)

    Liu, Dong; Liu, Zeng-Shan; Hu, Pan; Hui, Qi; Fu, Bao-Quan; Lu, Shi-Ying; Li, Yan-Song; Zou, De-Ying; Li, Zhao-Hui; Yan, Dong-Ming; Ding, Yan-Xia; Zhang, Yuan-Yuan; Zhou, Yu; Liu, Nan-Nan; Ren, Hong-Lin

    2016-08-01

    Poultry husbandry is a very important aspect of the agricultural economy in China. However, chicks are often susceptible to infectious disease microorganisms, such as bacteria, viruses and parasites, causing large economic losses in recent years. In the present study, we isolated an Acinetobacter baumannii strain, CCGGD201101, from diseased chicks in the Jilin Province of China. Regression analyses of virulence and LD50 tests conducted using healthy chicks confirmed that A. baumannii CCGGD201101, with an LD50 of 1.81 (±0.11) × 10(4) CFU, was more virulent than A. baumannii ATCC17978, with an LD50 of 1.73 (±0.13) × 10(7) CFU. Moreover, TEM examination showed that the pili of A. baumannii CCGGD201101 were different from those of ATCC17978. Antibiotic sensitivity analyses showed that A. baumannii CCGGD201101 was sensitive to rifampicin but resistant to most other antibiotics. These results imply that A. baumannii strain CCGGD201101 had both virulence enhancement and antibiotic resistance characteristics, which are beneficial for A. baumannii survival under adverse conditions and enhance fitness and invasiveness in the host. A. baumannii CCGGD20101, with its high virulence and antimicrobial resistance, may be one of the pathogens causing death of diseased chicks. © 2016 The Societies and John Wiley & Sons Australia, Ltd.

  17. Screening probiotic strains for safety: Evaluation of virulence and antimicrobial susceptibility of enterococci from healthy Chinese infants.

    Science.gov (United States)

    Zhang, Fen; Jiang, Meiling; Wan, Cuixiang; Chen, Xiaoyan; Chen, Xiaoyong; Tao, Xueying; Shah, Nagendra P; Wei, Hua

    2016-06-01

    The aim of this study was to evaluate the safety of enterococci isolated from Chinese infants and screen out potential probiotic candidates. One hundred eight strains were isolated from feces of 34 healthy infants, and 38 strains of Enterococcus spp. were categorized as follows: E. faecalis (22), E. faecium (10), E. hirae (3), E. durans (2), and E. casseliflavus (1). Of these, 72.7% of E. faecalis came from infants delivered by cesarean and 62.5% of E. faecium from infants delivered vaginally. For safety evaluation of strains, we determined presence of virulence genes; production of hemolysin, gelatinase, and biofilm; and antimicrobial susceptibility of enterococci. Six out of 14 virulence genes were detected with a distribution of gelE (26.3%), cylA (39.4%), esp (15.8%), efaA (63.2%), asa1 (50.0%), and ace (50.0%). In phenotype analysis, 36.8% of the strains exhibited positive hemolytic activity and 17.5% were positive for production of gelatinase. Results of antimicrobial susceptibility showed that different percentages of the strains were resistant to ciprofloxacin (5.2%), vancomycin (7.8%), rifampicin (10.5%), erythromycin (52.6%), and gentamycin (52.6%); remarkably, none of the strains were resistant to ampicillin or chloramphenicol. In total, 10 strains, including 6 E. faecium, which are free of virulence determinants and sensitive to common antimicrobial agents (e.g., ampicillin and vancomycin), were further assessed for their probiotic properties. All strains survived well in simulated gastric fluid and intestinal tract, with maximum reductions of 0.600 and 0.887 log cfu/mL, respectively. Six strains of E. faecium could resist 0.3 to 1.0% bile salt, of which E. faecium WEFA23 presented the highest growth (75.06%) at 1.0% bile salt. All strains showed bile salt hydrolase activity on glycodeoxycholic acid, but only 3 of E. faecium showed activity on taurodeoxycholic acid. These results deliver useful information on the safety of enterococci in infants in

  18. Virulence-related genes, adhesion and invasion of some Yersinia enterocolitica-like strains suggests its pathogenic potential.

    Science.gov (United States)

    Imori, Priscilla F M; Passaglia, Jaqueline; Souza, Roberto A; Rocha, Lenaldo B; Falcão, Juliana P

    2017-03-01

    Yersina enterocolitica-like species have not been extensively studied regarding its pathogenic potential. This work aimed to assess the pathogenic potential of some Y. enterocolitica-like strains by evaluating the presence of virulence-related genes by PCR and their ability to adhere to and invade Caco-2 and HEp-2 cells. A total of 50 Y. frederiksenii, 55 Y. intermedia and 13 Y. kristensenii strains were studied. The strains contained the following genes: Y. frederiksenii, fepA(44%), fes(44%) and ystB(18%); Y. intermedia, ail(53%), fepA (35%), fepD(2%), fes(97%), hreP(2%), ystB(2%) and tccC(35%); Y. kristensenii, ail(62%), ystB(23%), fepA(77%), fepD(54%), fes(54%) and hreP(77%). Generally, the Y. enterocolitica-like strains had a reduced ability to adhere to and invade mammalian cells compared to the highly pathogenic Y. enterocolitica 8081. However, Y. kristensenii FCF410 and Y. frederiksenii FCF461 presented high invasion potentials in Caco-2 cells after five days of pre-incubation increased by 45- and 7.2-fold compared to Y. enterocolitica 8081, respectively; but, the ail gene was not detected in these strains. The presence of virulence-related genes in some of the Y. enterocolitica-like strains indicated their possible pathogenic potential. Moreover, the results suggest the existence of alternative virulence mechanisms and that the pathogenicity of Y. kristensenii and Y. frederiksenii may be strain-dependent. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Processing plant persistent strains of Listeria monocytogenes appear to have a lower virulence potential than clinical strains in selected virulence models

    DEFF Research Database (Denmark)

    Jensen, Anne; Thomsen, L.E.; Jørgensen, R.L.

    2008-01-01

    Listeria monocytogenes is an important foodborne bacterial pathogen that can colonize food processing equipment. One group of genetically similar L. monocytogenes strains (RAPID type 9) was recently shown to reside in several independent fish processing plants. Persistent strains are likely...

  20. Transcriptome-Based Identification of Differently Expressed Genes from Xanthomonas oryzae pv. oryzae Strains Exhibiting Different Virulence in Rice Varieties.

    Science.gov (United States)

    Noh, Tae-Hwan; Song, Eun-Sung; Kim, Hong-Il; Kang, Mi-Hyung; Park, Young-Jin

    2016-02-19

    Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial blight (BB) in rice (Oryza sativa L.). In this study, we investigated the genome-wide transcription patterns of two Xoo strains (KACC10331 and HB1009), which showed different virulence patterns against eight rice cultivars, including IRBB21 (carrying Xa21). In total, 743 genes showed a significant change (p-value 2) in the HB1009 (K3a race) strain than in the Xoo KACC10331 (K1 race) strain. Furthermore, 13 and 12 genes involved in hypersensitive response and pathogenicity (hrp) and two-component regulatory systems (TCSs), respectively, were upregulated in the HB1009 (K3a race) strain compared with the Xoo KACC10331 (K1 race) strain, which we determined using either quantitative real-time PCR analysis or next-generation RNA sequencing. These results will be helpful to improve our understanding of Xoo and to gain a better insight into the Xoo-rice interactions.

  1. A live oral Lawsonia intracellularis vaccine does not result in protective immunity comparable to that of a virulent strain

    DEFF Research Database (Denmark)

    Hvass, Henriette Cordes; Riber, Ulla; Ståhl, Marie

    Lawsonia intracellularis is the cause of proliferative enteropathy, an economically important enteric disease in pigs that causes weight loss and failure to thrive. The disease is controllable with antibiotics and an attenuated live oral vaccine (Enterisol®) is used for prophylaxis. Still...... these interventions have not resulted in eradication of the bacteria, which is abundantly present in most pig herds in many countries, including Denmark. In the experimental study we present here, weaned pigs received the oral L. intracellularis vaccine or a virulent field strain (Re-I pigs). The latter resulting...... in subclinical disease. Both groups were treated with antibiotics from day 21 to 26 and challenged at day 49 with the virulent strain. A control group (CC) only received challenge. We here report on clinical outcome, L. intracellularis infection of the intestines and immunological responses. While Re-I pigs had...

  2. Genetic Virulence Profile of Enteroaggregative Escherichia coli Strains Isolated from Danish Children with Either Acute or Persistent Diarrhea

    DEFF Research Database (Denmark)

    Hebbelstrup Jensen, Betina; Poulsen, Anja; Hebbelstrup Rye Rasmussen, Stig

    2017-01-01

    with an expected severe disease course. Questionnaires answered by parents provided information regarding duration of diarrhea and presence of blood or mucus. A total of 295 EAEC strains were collected from children with acute (≤7 days) and persistent diarrhea (≥14 days) and were compared by using multiplex PCR......Enteroaggregative Escherichia coli (EAEC) is frequently found in diarrheal stools worldwide. It has been associated with persistent diarrhea, weight loss, and failure to thrive in children living in developing countries. A number of important EAEC virulence genes are identified; however......, their roles in acute and persistent diarrhea have not been previously investigated. The aim of this study was to identify specific EAEC virulence genes associated with duration and type of diarrhea in Danish children. We aimed to improve the current diagnostics of EAEC and enable targeting of strains...

  3. Inactivation and Gene Expression of a Virulent WastewaterEscherichia coliStrain and the Nonvirulent CommensalEscherichia coliDSM1103 Strain upon Solar Irradiation

    KAUST Repository

    Aljassim, Nada I.

    2017-03-06

    This study examined the decay kinetics and molecular responses of two Escherichia coli strains upon solar irradiation. The first is E. coli PI-7, a virulent and antibiotic-resistant strain that was isolated from wastewater and carries the emerging NDM-1 antibiotic resistance gene. The other strain, E. coli DSM1103, displayed lower virulence and antibiotic resistance than E. coli PI-7. In a buffer solution, E. coli PI-7 displayed a longer lag phase prior to decay and a longer half-life compared with E. coli DSM1103 (6.64 ± 0.63 h and 2.85 ± 0.46 min vs 1.33 ± 0.52 h and 2.04 ± 0.36 min). In wastewater, both E. coli strains decayed slower than they did in buffer. Although solar irradiation remained effective in reducing the numbers of both strains by more than 5-log10 in <24 h, comparative genomics and transcriptomics revealed differences in the genomes and overall regulation of genes between the two E. coli strains. A wider arsenal of genes related to oxidative stress, cellular repair and protective mechanisms were upregulated in E. coli PI-7. Subpopulations of E. coli PI-7 expressed genes related to dormancy and persister cell formation during the late decay phase, which may have accounted for its prolonged persistence. Upon prolonged solar irradiation, both E. coli strains displayed upregulation of genes related to horizontal gene transfer and antibiotic resistance. Virulence functions unique to E. coli PI-7 were also upregulated. Our findings collectively indicated that, whereas solar irradiation is able to reduce total cell numbers, viable E. coli remained and expressed genes that enable survival despite solar treatment. There remains a need for heightened levels of concern regarding risks arising from the dissemination of E. coli that may remain viable in wastewater after solar irradiation.

  4. Molecular analyses of the hemagglutinin genes of H5 influenza viruses: origin of a virulent turkey strain.

    Science.gov (United States)

    Kawaoka, Y; Nestorowicz, A; Alexander, D J; Webster, R G

    1987-05-01

    Comparative sequence analysis of the hemagglutinin (HA) genes of a highly virulent H5N8 virus isolated from turkeys in Ireland in 1983 and a virus of the same subtype detected simultaneously in healthy ducks showed only four amino acid differences between these strains. Partial sequencing of six of the other genes and antigenic similarity of the neuraminidases established the overall genetic similarity of these two viruses. Comparison of the complete sequence of two H5 gene sequences and partial sequences of other virulent and avirulent H5 viruses provides evidence for at least two different lineages of H5 influenza virus in the world, one in Europe and the other in North America, with virulent and avirulent members in each group. In vivo studies in domestic ducks showed that all of the H5 viruses that are virulent in chickens and turkeys replicate in the internal organs of ducks but did not produce any disease signs. Additionally, both viruses isolated from turkeys and ducks in Ireland were detected in the blood. These studies provide the first conclusive evidence for the possibility that fully virulent influenza viruses in domestic poultry can arise directly from viruses in wild aquatic birds. Studies on the cleavability of the HA of virulent and avirulent H5 viruses showed that the principles established for H7 viruses (F. X. Bosch, M. Orlich, H. D. Klenk, and R. Rott, 1979, Virology 95, 197-207; F. X. Bosch, W. Garten, H. D. Klenk, and R. Rott, 1981, Virology 113, 725-735) also apply to the H5 subtype. These are (1) only the HAs of virulent influenza viruses were cleaved in tissue culture in the absence of trypsin and (2) virulent H5 influenza viruses contain a series of basic amino acids at the cleavage site of the HA, whereas avirulent strains contain only a single arginine with the exception of the avirulent Chicken/Pennsylvania virus. Thus, a series of basic amino acids at the cleavage site probably forms a recognition site for the enzyme(s) responsible for

  5. Genomic Changes in an Attenuated ZB Strain of Foot-and-Mouth Disease Virus Serotype Asia1 and Comparison with Its Virulent Parental Strain

    Directory of Open Access Journals (Sweden)

    Aiguo Xin

    2014-01-01

    Full Text Available The molecular basis of attenuation of foot-and-mouth disease virus (FMDV serotype Asia1 ZB strain remains unknown. To understand the genetic changes of attenuation, we compared the entire genomes of three different rabbit-passaged attenuated ZB strains (ZB/CHA/58(att, ZBRF168, and ZBRF188 and their virulent parental strains (ZBCF22 and YNBS/58. The results showed that attenuation may be brought about by 28 common amino acid substitutions in the coding region, with one nucleotide point mutation in the 5′-untranslated region (5′-UTR and another one in the 3′-UTR. In addition, a total of 21 nucleotides silent mutations had been found after attenuation. These substitutions, alone or in combination, may be responsible for the attenuated phenotype of the ZB strain in cattle. This will contribute to elucidation of attenuating molecular basis of the FMDV ZB strain.

  6. Virulence potential of Enterococcus gallinarum strains isolated from selected Nigerian traditional fermented foods

    OpenAIRE

    IYABO C. OLADIPO; ABIODUN I. SANNI; SNEHASIKTAS SWARNAKAR

    2014-01-01

    Five Enterococcus isolates from some Nigerian traditional fermented foods were identified as Enterococcus gallinarum by using phenotypic and genotypic tests. Safety properties such as antibiotic susceptibility, virulence gene detection, haemolysin, gelatinase and bacteriocin production were determined using standard methods. There was no resistance to clinically relevant antibiotics. Virulence gene for collagen binding antigen and aggregation substance were detected in 60% of the E. gallinaru...

  7. On the analysis of the virulence nature of TIGR4 and R6 strains of ...

    Indian Academy of Sciences (India)

    WINTEC

    gated, as virulence factors as potential vaccine or drug targets. Structural and biochemical studies of these pneumococcal virulence factors have facilitated the development of novel antibiotics or protein an- tigen-based vaccines for the treatment of pneumococcal disease. Here we describe the comparison bet- ween the ...

  8. Myxomatosis: the virulence of field strains of myxoma virus in a population of wild rabbits (Oryctolagus cuniculus L.) with high resistance to myxomatosis.

    Science.gov (United States)

    Edmonds, J W; Nolan, I F; Shepherd, R C; Gocs, A

    1975-06-01

    The virulence of field strains of myxoma virus is increasing in the Mallee region of Victoria where the resistance of the rabbit to myxomatosis is high. This suggests that the climax association will be a moderately severe disease.

  9. Draft genome sequence for virulent and avirulent strains of Xanthomonas arboricola isolated from Prunus spp. in Spain.

    Science.gov (United States)

    Garita-Cambronero, Jerson; Palacio-Bielsa, Ana; López, María M; Cubero, Jaime

    2016-01-01

    Xanthomonas arboricola is a species in genus Xanthomonas which is mainly comprised of plant pathogens. Among the members of this taxon, X. arboricola pv. pruni, the causal agent of bacterial spot disease of stone fruits and almond, is distributed worldwide although it is considered a quarantine pathogen in the European Union. Herein, we report the draft genome sequence, the classification, the annotation and the sequence analyses of a virulent strain, IVIA 2626.1, and an avirulent strain, CITA 44, of X. arboricola associated with Prunus spp. The draft genome sequence of IVIA 2626.1 consists of 5,027,671 bp, 4,720 protein coding genes and 50 RNA encoding genes. The draft genome sequence of strain CITA 44 consists of 4,760,482 bp, 4,250 protein coding genes and 56 RNA coding genes. Initial comparative analyses reveals differences in the presence of structural and regulatory components of the type IV pilus, the type III secretion system, the type III effectors as well as variations in the number of the type IV secretion systems. The genome sequence data for these strains will facilitate the development of molecular diagnostics protocols that differentiate virulent and avirulent strains. In addition, comparative genome analysis will provide insights into the plant-pathogen interaction during the bacterial spot disease process.

  10. Entamoeba histolytica: expression and localization of Gal/GalNAc lectin in virulent and non-virulent variants from HM1:IMSS strain.

    Science.gov (United States)

    López-Vancell, R; Arreguín Espinosa, R; González-Canto, A; Néquiz Avendaño, M; García de León, M C; Olivos-García, A; López-Vancell, D; Pérez-Tamayo, R

    2010-07-01

    We have purified Gal/GalNAc lectin from Entamoeba histolytica by electroelution. The purified protein was used to immunize rabbits and obtain polyclonal IgG's anti-lectin. These antibodies were used as tools to analyze the expression and localization of the amoebic lectin in both virulent (vEh) and non-virulent (nvEh) variants of axenically cultured HM1:IMSS strain. vEh is able to induce liver abscesses in hamsters, whereas nvEh has lost this ability. In vitro, amoebic trophozoites from both variants equally express this protein as shown by densitometric analysis of the corresponding band in Western blots from lysates. In both types of trophozoites, the pattern of distribution of the lectin was mainly on the surface. We have also compared by immunohistochemistry the presence and distribution of lectin in the in vivo liver lesions produced in hamsters. In order to prolong the survival of nvEh to analyze both variants in an in vivo model, hamsters inoculated with nvEh were treated with methyl prednisolone. Our results suggest that the Gal/GalNAc lectin is equally expressed in both nvEh and vEh.

  11. Antibiotic resistance and virulence genes in enterococcus strains isolated from different hospitals in Saudi Arabia

    Directory of Open Access Journals (Sweden)

    Mohamed M. Hassan

    2016-07-01

    Full Text Available The purpose of this study was molecular characterization of the antibiotic resistance profiles of some Enterococcus isolates obtained from different hospitals in Taif governorate in KSA. Out of the 89 bacterial isolates obtained, 12 isolates of Enterococcus spp. were subjected to fingerprinting based on repetitive sequence-based polymerase chain reaction (Rep-PCR, and tested their resistance/susceptibility against some antibiotics which are commonly used in KSA. They were identified using the specific primers for different antibiotic resistance genes of Enterococcus spp. as Tuf, VanC-1, VanC-2-VanC-3 genes and sequencing fragments of 16S rDNA gene. The obtained results indicated that about 58.3% of Enterococcus isolates were Enterococcus faecium, 16.6% were Enterococcus durans and 25.1% were other Enterococcus species. Sixty-seven per cent of the isolates had multi-drug resistance patterns against gentamicin, vancomycin, erythromycin, amoxicillin, cefazolin and tetracycline. Data on the prevalence and types of antibiotic resistance in Enterococcus species may be used to describe baseline antibiotic susceptibility profiles associated with Enterococcus spp. that were isolated from the hospitals’ environment. Some discrepancies were detected among the identification methods used, and the most reliable were the Tuf, VanC-1, VanC-2-VanC-3 genes, and 16S rDNA nucleotide sequencing of 12 Enterococcus isolates were deposited in Gene Bank under the accession numbers from KT366721 to KT366732, respectively. Selected isolates exhibited susceptibility to almost all studied antibiotics, and some virulence factors were detected by PCR. Finally, these Enterococcus isolates were molecularly characterized by Rep-PCR into a diverse genetic background. The data collected may also help to elucidate the role of hospitals in the transmission of antibiotic-resistant strains to human populations.

  12. Isolation, Antimicrobial Resistance, and Virulence Genes of Pasteurella multocida Strains from Swine in China▿

    Science.gov (United States)

    Tang, Xibiao; Zhao, Zhanqin; Hu, Junyong; Wu, Bin; Cai, Xuwang; He, Qigai; Chen, Huanchun

    2009-01-01

    A total of 233 isolates of Pasteurella multocida were obtained from 2,912 cases of clinical respiratory disease in pigs in China, giving an isolation rate of 8.0%. Serogroup A P. multocida isolates were isolated from 92 cases (39.5%), and serogroup D isolates were isolated from 128 cases (54.9%); 12 isolates (5.2%) were untypeable. P. multocida was the fourth most frequent pathogenic bacterium recovered from the respiratory tract, after Streptococcus suis, Haemophilus parasuis, and Escherichia coli. All isolates were characterized for their susceptibilities to 20 antibiotics and the presence of 19 genes for virulence factors (VFs). The frequency of antimicrobial resistance among P. multocida isolates from swine in China was higher than that reported among P. multocida isolates from swine in from other countries, and 93.1% of the isolates showed multiple-drug resistance. There was a progressive increase in the rate of multiresistance to more than seven antibiotics, from 16.2% in 2003 to 62.8% in 2007. The resistance profiles suggested that cephalosporins, florfenicol, and fluoroquinolones were the drugs most likely to be active against P. multocida. Use of PCR showed that colonization factors (ptfA, fimA, and hsf-2), iron acquisition factors, sialidases (nanH), and outer membrane proteins occurred in most porcine strains. The VFs pfhA, tadD, toxA, and pmHAS were each present in multocida isolates and suggest that the potential threat of such multiresistant bacteria in food-producing animals should not be neglected. PMID:19158260

  13. Isolation, antimicrobial resistance, and virulence genes of Pasteurella multocida strains from swine in China.

    Science.gov (United States)

    Tang, Xibiao; Zhao, Zhanqin; Hu, Junyong; Wu, Bin; Cai, Xuwang; He, Qigai; Chen, Huanchun

    2009-04-01

    A total of 233 isolates of Pasteurella multocida were obtained from 2,912 cases of clinical respiratory disease in pigs in China, giving an isolation rate of 8.0%. Serogroup A P. multocida isolates were isolated from 92 cases (39.5%), and serogroup D isolates were isolated from 128 cases (54.9%); 12 isolates (5.2%) were untypeable. P. multocida was the fourth most frequent pathogenic bacterium recovered from the respiratory tract, after Streptococcus suis, Haemophilus parasuis, and Escherichia coli. All isolates were characterized for their susceptibilities to 20 antibiotics and the presence of 19 genes for virulence factors (VFs). The frequency of antimicrobial resistance among P. multocida isolates from swine in China was higher than that reported among P. multocida isolates from swine in from other countries, and 93.1% of the isolates showed multiple-drug resistance. There was a progressive increase in the rate of multiresistance to more than seven antibiotics, from 16.2% in 2003 to 62.8% in 2007. The resistance profiles suggested that cephalosporins, florfenicol, and fluoroquinolones were the drugs most likely to be active against P. multocida. Use of PCR showed that colonization factors (ptfA, fimA, and hsf-2), iron acquisition factors, sialidases (nanH), and outer membrane proteins occurred in most porcine strains. The VFs pfhA, tadD, toxA, and pmHAS were each present in multocida isolates and suggest that the potential threat of such multiresistant bacteria in food-producing animals should not be neglected.

  14. Indole-3-acetaldehyde dehydrogenase-dependent auxin synthesis contributes to virulence of Pseudomonas syringae strain DC3000.

    Directory of Open Access Journals (Sweden)

    Sheri A McClerklin

    2018-01-01

    Full Text Available The bacterial pathogen Pseudomonas syringae modulates plant hormone signaling to promote infection and disease development. P. syringae uses several strategies to manipulate auxin physiology in Arabidopsis thaliana to promote pathogenesis, including its synthesis of indole-3-acetic acid (IAA, the predominant form of auxin in plants, and production of virulence factors that alter auxin responses in the host; however, the role of pathogen-derived auxin in P. syringae pathogenesis is not well understood. Here we demonstrate that P. syringae strain DC3000 produces IAA via a previously uncharacterized pathway and identify a novel indole-3-acetaldehyde dehydrogenase, AldA, that functions in IAA biosynthesis by catalyzing the NAD-dependent formation of IAA from indole-3-acetaldehyde (IAAld. Biochemical analysis and solving of the 1.9 Å resolution x-ray crystal structure reveal key features of AldA for IAA synthesis, including the molecular basis of substrate specificity. Disruption of aldA and a close homolog, aldB, lead to reduced IAA production in culture and reduced virulence on A. thaliana. We use these mutants to explore the mechanism by which pathogen-derived auxin contributes to virulence and show that IAA produced by DC3000 suppresses salicylic acid-mediated defenses in A. thaliana. Thus, auxin is a DC3000 virulence factor that promotes pathogenicity by suppressing host defenses.

  15. Rhoptry Proteins ROP5 and ROP18 Are Major Murine Virulence Factors in Genetically Divergent South American Strains of Toxoplasma gondii.

    Directory of Open Access Journals (Sweden)

    Michael S Behnke

    2015-08-01

    Full Text Available Toxoplasma gondii has evolved a number of strategies to evade immune responses in its many hosts. Previous genetic mapping of crosses between clonal type 1, 2, and 3 strains of T. gondii, which are prevalent in Europe and North America, identified two rhoptry proteins, ROP5 and ROP18, that function together to block innate immune mechanisms activated by interferon gamma (IFNg in murine hosts. However, the contribution of these and other virulence factors in more genetically divergent South American strains is unknown. Here we utilized a cross between the intermediately virulent North American type 2 ME49 strain and the highly virulent South American type 10 VAND strain to map the genetic basis for differences in virulence in the mouse. Quantitative trait locus (QTL analysis of this new cross identified one peak that spanned the ROP5 locus on chromosome XII. CRISPR-Cas9 mediated deletion of all copies of ROP5 in the VAND strain rendered it avirulent and complementation confirmed that ROP5 is the major virulence factor accounting for differences between type 2 and type 10 strains. To extend these observations to other virulent South American strains representing distinct genetic populations, we knocked out ROP5 in type 8 TgCtBr5 and type 4 TgCtBr18 strains, resulting in complete loss of virulence in both backgrounds. Consistent with this, polymorphisms that show strong signatures of positive selection in ROP5 were shown to correspond to regions known to interface with host immunity factors. Because ROP5 and ROP18 function together to resist innate immune mechanisms, and a significant interaction between them was identified in a two-locus scan, we also assessed the role of ROP18 in the virulence of South American strains. Deletion of ROP18 in South American type 4, 8, and 10 strains resulted in complete attenuation in contrast to a partial loss of virulence seen for ROP18 knockouts in previously described type 1 parasites. These data show that ROP5

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

    Science.gov (United States)

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

    2017-07-01

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

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

    Directory of Open Access Journals (Sweden)

    M.G. Ribeiro

    2006-10-01

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

  18. Increasing virulence, but not infectivity, associated with serially emergent virus strains of a fish rhabdovirus

    Science.gov (United States)

    Breyta, Rachel; McKenney, Douglas; Tesfaye, Tarin; Ono, Kotaro; Kurath, Gael

    2016-01-01

    Surveillance and genetic typing of field isolates of a fish rhabdovirus, infectious hematopoietic necrosis virus (IHNV), has identified four dominant viral genotypes that were involved in serial viral emergence and displacement events in steelhead trout (Oncorhynchus mykiss) in western North America. To investigate drivers of these landscape-scale events, IHNV isolates designated 007, 111, 110, and 139, representing the four relevant genotypes, were compared for virulence and infectivity in controlled laboratory challenge studies in five relevant steelhead trout populations. Viral virulence was assessed as mortality using lethal dose estimates (LD50), survival kinetics, and proportional hazards analysis. A pattern of increasing virulence for isolates 007, 111, and 110 was consistent in all five host populations tested, and correlated with serial emergence and displacements in the virus-endemic lower Columbia River source region during 1980–2013. The fourth isolate, 139, did not have higher virulence than the previous isolate 110. However, the mG139M genotype displayed a conditional displacement phenotype in that it displaced type mG110M in coastal Washington, but not in the lower Columbia River region, indicating that factors other than evolution of higher viral virulence were involved in some displacement events. Viral infectivity, measured as infectious dose (ID50), did not correlate consistently with virulence or with viral emergence, and showed a narrow range of variation relative to the variation observed in virulence. Comparison among the five steelhead trout populations confirmed variation in resistance to IHNV, but correlations with previous history of virus exposure or with sites of viral emergence varied between IHNV source and sink regions. Overall, this study indicated increasing viral virulence over time as a potential driver for emergence and displacement events in the endemic Lower Columbia River source region where these IHNV genotypes originated

  19. Transmission selects for HIV-1 strains of intermediate virulence: a modelling approach.

    Directory of Open Access Journals (Sweden)

    George Shirreff

    2011-10-01

    Full Text Available Recent data shows that HIV-1 is characterised by variation in viral virulence factors that is heritable between infections, which suggests that viral virulence can be naturally selected at the population level. A trade-off between transmissibility and duration of infection appears to favour viruses of intermediate virulence. We developed a mathematical model to simulate the dynamics of putative viral genotypes that differ in their virulence. As a proxy for virulence, we use set-point viral load (SPVL, which is the steady density of viral particles in blood during asymptomatic infection. Mutation, the dependency of survival and transmissibility on SPVL, and host effects were incorporated into the model. The model was fitted to data to estimate unknown parameters, and was found to fit existing data well. The maximum likelihood estimates of the parameters produced a model in which SPVL converged from any initial conditions to observed values within 100-150 years of first emergence of HIV-1. We estimated the 1 host effect and 2 the extent to which the viral virulence genotype mutates from one infection to the next, and found a trade-off between these two parameters in explaining the variation in SPVL. The model confirms that evolution of virulence towards intermediate levels is sufficiently rapid for it to have happened in the early stages of the HIV epidemic, and confirms that existing viral loads are nearly optimal given the assumed constraints on evolution. The model provides a useful framework under which to examine the future evolution of HIV-1 virulence.

  20. Caracterização da virulência da cepa de Escherichia coli - BK99 Virulence characterization of strain Escherichia coli - BK99

    Directory of Open Access Journals (Sweden)

    Benito Guimarães de Brito

    2001-06-01

    Full Text Available Com o objetivo de identificar a patogenicidade e resistência a antimicrobianos da cepa de E. coli BK99, foram utilizados alguns testes: aglutinação em lâmina para detecção da fímbria F5, produção de STa, ensaios para hemolisinas e colicinas, patogenicidade em leitões e antibiograma. A cepa BK99 apresentou o seguinte perfil: F1+, F5+, STa+, Col V+, Hly-, ST R, KA R, NO R, TT R SF R e foi capaz de provocar a doença clínica e morte em leitões inoculados; também foi possível o resgate dessa cepa de fezes diarréicas e do conteúdo intestinal dos leitões revelando, assim, alto índice de recuperação de colônias portadoras da fímbria F5+. Os resultados permitem concluir que a cepa de E. coli BK99 é produtora de fatores de virulência e reproduz experimentalmente a colibacilose suína neonatal.In order to evaluate the pathogenicity and antimicrobial resistance pattern of BK99 E. coli strain, several tests were assessed: slide agglutination for detection of the fimbriae F5, STa production, hemolytic and colicin activity, pathogenicity assessement using piglet inoculation and antimicrobial resistance to drugs. The strain BK99 showed the following profile: F1+, F5+, STa+, Col V+, Hly-, ST R, KA R, NO R, TT R SF R. It produced clinical disease and death of infected piglets. Moreover, it was possible to recover the BK99 strain from diarrheic feces and from the gut contents of the piglet, with high rate of recovery of colonies expressing fimbriae F5+. The present results suggest that the E. coli BK99 strain could produce virulence factors and experimentally reproduce neonatal colibacillosis in pigs.

  1. Comparison of the live attenuated yellow fever vaccine 17D-204 strain to its virulent parental strain Asibi by deep sequencing.

    Science.gov (United States)

    Beck, Andrew; Tesh, Robert B; Wood, Thomas G; Widen, Steven G; Ryman, Kate D; Barrett, Alan D T

    2014-02-01

    The first comparison of a live RNA viral vaccine strain to its wild-type parental strain by deep sequencing is presented using as a model the yellow fever virus (YFV) live vaccine strain 17D-204 and its wild-type parental strain, Asibi. The YFV 17D-204 vaccine genome was compared to that of the parental strain Asibi by massively parallel methods. Variability was compared on multiple scales of the viral genomes. A modeled exploration of small-frequency variants was performed to reconstruct plausible regions of mutational plasticity. Overt quasispecies diversity is a feature of the parental strain, whereas the live vaccine strain lacks diversity according to multiple independent measurements. A lack of attenuating mutations in the Asibi population relative to that of 17D-204 was observed, demonstrating that the vaccine strain was derived by discrete mutation of Asibi and not by selection of genomes in the wild-type population. Relative quasispecies structure is a plausible correlate of attenuation for live viral vaccines. Analyses such as these of attenuated viruses improve our understanding of the molecular basis of vaccine attenuation and provide critical information on the stability of live vaccines and the risk of reversion to virulence.

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

    Science.gov (United States)

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

    2017-09-06

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

  3. Attenuation mechanism of virulent infectious bronchitis virus strain with QX genotype by continuous passage in chicken embryos.

    Science.gov (United States)

    Huo, Ya-fei; Huang, Qing-hua; Lu, Mei; Wu, Jia-qiang; Lin, Shu-qian; Zhu, Fengzhu; Zhang, Xiu-mei; Huang, Yan-yan; Yang, Shao-hua; Xu, Chuan-tian

    2016-01-02

    The virulent isolate SDZB0808 of QX-type infectious bronchitis virus (IBV) was continuously passaged in chicken embryos for 110 generations. The safety and immune efficacy of the 110th generation of IBVs (P110) were evaluated. Damage was not found in the appearance of the 3-day-old specific-pathogen-free (SPF) chicks immunized with 10(4.5) EID50 (median embryo infective dose) of P110 by intranasal and ocular administration. At 14 d after the vaccination with 10(4.5) EID50 of P110, all the 3-day-old SPF chicks were immune from the attack of the homologous virulent strain SDZB0808 and the heterologous virulent strain SDIB821/2012. The whole genome sequencing of SDZB0808 of different generations (P1-P110) indicated that the replicase 1a sequences of P60-P110 all lost a length of 30bp in the same region. Specific primers were designed according to the differences in the genomes of P1-P110. SYBR Green I real-time quantitative PCR was adopted to analyze the proportion of the viruses with 30bp deletion in P60, P100, and P110. Results showed that with the passage in chicken embryos, the proportion of the viruses with 30bp deletion gradually increased. Almost 100% of the viruses in the P110 had 30bp deletion in the replicase 1a sequence. Therefore, the attenuation of IBV's virulence may be the outcome of directional screening in the chicken embryos. This work confirmed the high safety and immune efficacy of P110 in SPF chickens. Thus, P110 can serve as an attenuated IBV vaccine candidate. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Comparative genome analysis of an avirulent and two virulent strains of avian Pasteurella multocida reveals candidate genes involved in fitness and pathogenicity

    Science.gov (United States)

    2013-01-01

    Background Pasteurella multocida is the etiologic agent of fowl cholera, a highly contagious and severe disease of poultry causing significant mortality and morbidity throughout the world. All types of poultry are susceptible to fowl cholera. Turkeys are most susceptible to the peracute/acute forms of the disease while chickens are most susceptible to the acute and chronic forms of the disease. The whole genome of the Pm70 strain of P. multocida was sequenced and annotated in 2001. The Pm70 strain is not virulent to chickens and turkeys. In contrast, strains X73 and P1059 are highly virulent to turkeys, chickens, and other poultry species. In this study, we sequenced the genomes of P. multocida strains X73 and P1059 and undertook a detailed comparative genome analysis with the avirulent Pm70 strain. The goal of this study was to identify candidate genes in the virulent strains that may be involved in pathogenicity of fowl cholera disease. Results Comparison of virulent versus avirulent avian P. multocida genomes revealed 336 unique genes among the P1059 and/or X73 genomes compared to strain Pm70. Genes of interest within this subset included those encoding an L-fucose transport and utilization system, several novel sugar transport systems, and several novel hemagglutinins including one designated PfhB4. Additionally, substantial amino acid variation was observed in many core outer membrane proteins and single nucleotide polymorphism analysis confirmed a higher dN/dS ratio within proteins localized to the outer membrane. Conclusions Comparative analyses of highly virulent versus avirulent avian P. multocida identified a number of genomic differences that may shed light on the ability of highly virulent strains to cause disease in the avian host, including those that could be associated with enhanced virulence or fitness. PMID:23672515

  5. Inference of antibiotic resistance and virulence among diverse group A Streptococcus strains using emm sequencing and multilocus genotyping methods.

    Directory of Open Access Journals (Sweden)

    David Metzgar

    Full Text Available BACKGROUND: Group A Streptococcus pyogenes (GAS exhibits a high degree of clinically relevant phenotypic diversity. Strains vary widely in terms of antibiotic resistance (AbR, clinical severity, and transmission rate. Currently, strain identification is achieved by emm typing (direct sequencing of the genomic segment coding for the antigenic portion of the M protein or by multilocus genotyping methods. Phenotype analysis, including critical AbR typing, is generally achieved by much slower and more laborious direct culture-based methods. METHODOLOGY/PRINCIPAL FINDINGS: We compare genotype identification (by emm typing and PCR/ESI-MS with directly measured phenotypes (AbR and outbreak associations for 802 clinical isolates of GAS collected from symptomatic patients over a period of 6 years at 10 military facilities in the United States. All independent strain characterization methods are highly correlated. This shows that recombination, horizontal transfer, and other forms of reassortment are rare in GAS insofar as housekeeping genes, primary virulence and antibiotic resistance determinants, and the emm gene are concerned. Therefore, genotyping methods offer an efficient way to predict emm type and the associated AbR and virulence phenotypes. CONCLUSIONS/SIGNIFICANCE: The data presented here, combined with much historical data, suggest that emm typing assays and faster molecular methods that infer emm type from genomic signatures could be used to efficiently infer critical phenotypic characteristics based on robust genotype: phenotype correlations. This, in turn, would enable faster and better-targeted responses during identified outbreaks of constitutively resistant or particularly virulent emm types.

  6. Whole-Genome Sequence Analysis and Genome-Wide Virulence Gene Identification of Riemerella anatipestifer Strain Yb2.

    Science.gov (United States)

    Wang, Xiaolan; Ding, Chan; Wang, Shaohui; Han, Xiangan; Yu, Shengqing

    2015-08-01

    Riemerella anatipestifer is a well-described pathogen of waterfowl and other avian species that can cause septicemic and exudative diseases. In this study, we sequenced the complete genome of R. anatipestifer strain Yb2 and analyzed it against the published genomic sequences of R. anatipestifer strains DSM15868, RA-GD, RA-CH-1, and RA-CH-2. The Yb2 genome contains one circular chromosome of 2,184,066 bp with a 35.73% GC content and no plasmid. The genome has 2,021 open reading frames that occupy 90.88% of the genome. A comparative genomic analysis revealed that genome organization is highly conserved among R. anatipestifer strains, except for four inversions of a sequence segment in Yb2. A phylogenetic analysis found that the closest neighbor of Yb2 is RA-GD. Furthermore, we constructed a library of 3,175 mutants by random transposon mutagenesis, and 100 mutants exhibiting more than 100-fold-attenuated virulence were obtained by animal screening experiments. Southern blot analysis and genetic characterization of the mutants led to the identification of 49 virulence genes. Of these, 25 encode cytoplasmic proteins, 6 encode cytoplasmic membrane proteins, 4 encode outer membrane proteins, and the subcellular localization of the remaining 14 gene products is unknown. The functional classification of orthologous-group clusters revealed that 16 genes are associated with metabolism, 6 are associated with cellular processing and signaling, and 4 are associated with information storage and processing. The functions of the other 23 genes are poorly characterized or unknown. This genome-wide study identified genes important to the virulence of R. anatipestifer. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  7. The virulence factor ychO has a pleiotropic action in an Avian Pathogenic Escherichia coli (APEC) strain.

    Science.gov (United States)

    Pilatti, Livia; Boldrin de Paiva, Jacqueline; Rojas, Thaís Cabrera Galvão; Leite, Janaína Luisa; Conceição, Rogério Arcuri; Nakazato, Gerson; Dias da Silveira, Wanderley

    2016-03-10

    Avian pathogenic Escherichia coli strains cause extraintestinal diseases in birds, leading to substantial economic losses to the poultry industry worldwide. Bacteria that invade cells can overcome the host humoral immune response, resulting in a higher pathogenicity potential. Invasins are members of a large family of outer membrane proteins that allow pathogen invasion into host cells by interacting with specific receptors on the cell surface. An in silico analysis of the genome of a septicemic APEC strain (SEPT362) demonstrated the presence of a putative invasin homologous to the ychO gene from E. coli str. K-12 substr. MG1655. In vitro and in vivo assays comparing a mutant strain carrying a null mutation of this gene, a complemented strain, and its counterpart wild-type strain showed that ychO plays a role in the pathogenicity of APEC strain SEPT362. In vitro assays demonstrated that the mutant strain exhibited significant decreases in bacterial adhesiveness and invasiveness in chicken cells and biofilm formation. In vivo assay indicated a decrease in pathogenicity of the mutant strain. Moreover, transcriptome analysis demonstrated that the ychO deletion affected the expression of 426 genes. Among the altered genes, 93.66% were downregulated in the mutant, including membrane proteins and metabolism genes. The results led us to propose that gene ychO contributes to the pathogenicity of APEC strain SEPT362 influencing, in a pleiotropic manner, many biological characteristics, such as adhesion and invasion of in vitro cultured cells, biofilm formation and motility, which could be due to the possible membrane location of this protein. All of these results suggest that the absence of gene ychO would influence the virulence of the APEC strain herein studied.

  8. An attemp at reversibility and increase of the virulence of axenic strains of Entamoeba histolytica Tentativa de reversibilidade e aumento de virulência de cepas axônicas de Entamoeba histolytica

    Directory of Open Access Journals (Sweden)

    Maria Aparecida Gomes

    1993-12-01

    Full Text Available In this study we have tried to verify whether the interaction "in vitro" with bacteria or small pieces of normal hamster liver would modify the pathogenic behavior of axenic strains of E. histolytica: avirulent ones (ICB-32 and ICB-RPS, of attenuated virulence (ICB-CSP and HM1 and of mean virulence (ICB-462. Every attempt to render virulent, recover or increase the virulence of axenic strains of E. histolytica has failedNeste trabalho procuramos verificar se a interação "in vitro" com bactérias e fragmentos de fígado de hamster normal, modificaria o comportamento patogênico de cepas axênicas de E. histolytica avirulentas (ICB-32 e ICB-RPS; virulentas, porém atenuadas (ICB-CSP e HM1 e de média virulência (ICB-462. Todas as tentativas de tornar virulentas, restabelecer ou aumentar a virulência das cepas axênicas de E. histolytica utilizadas fracassaram

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

    DEFF Research Database (Denmark)

    Schwager, Stephan; Agnoli, Kirsty; Köthe, Manuela

    2013-01-01

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

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

    DEFF Research Database (Denmark)

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

    2017-01-01

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

  11. The genome of a clinical Klebsiella variicola strain reveals virulence-associated traits and a pl9-like plasmid.

    Science.gov (United States)

    Andrade, Bruno Gabriel N; de Veiga Ramos, Nilceia; Marin, Michel F Abanto; Fonseca, Erica L; Vicente, Ana Carolina P

    2014-11-01

    Klebsiella species frequently cause clinically relevant human infections worldwide. We report the draft genome sequence of a Brazilian clinical isolate (Bz19) of the recently recognized species Klebsiella variicola. The comparison of Bz19 genome content with the At-22 (environmental K. variicola) and several clinical Klebsiella pneumoniae shows that these species share a set of virulence-associated determinants. Of note, this K. variicola strain harbours a plasmid-like element that shares the same backbone present in a multidrug-resistant plasmid found in a clinical K. pneumoniae isolated in USA.

  12. Live Attenuated Mutants of Francisella tularensis Protect Rabbits against Aerosol Challenge with a Virulent Type A Strain

    Science.gov (United States)

    Smith, Le'Kneitah P.; Cole, Kelly Stefano; Santiago, Araceli E.; Mann, Barbara J.; Barry, Eileen M.

    2014-01-01

    Francisella tularensis, a Gram-negative bacterium, is the causative agent of tularemia. No licensed vaccine is currently available for protection against tularemia, although an attenuated strain, dubbed the live vaccine strain (LVS), is given to at-risk laboratory personnel as an investigational new drug (IND). In an effort to develop a vaccine that offers better protection, recombinant attenuated derivatives of a virulent type A strain, SCHU S4, were evaluated in New Zealand White (NZW) rabbits. Rabbits vaccinated via scarification with the three attenuated derivatives (SCHU S4 ΔguaBA, ΔaroD, and ΔfipB strains) or with LVS developed a mild fever, but no weight loss was detected. Twenty-one days after vaccination, all vaccinated rabbits were seropositive for IgG to F. tularensis lipopolysaccharide (LPS). Thirty days after vaccination, all rabbits were challenged with aerosolized SCHU S4 at doses ranging from 50 to 500 50% lethal doses (LD50). All rabbits developed fevers and weight loss after challenge, but the severity was greater for mock-vaccinated rabbits. The ΔguaBA and ΔaroD SCHU S4 derivatives provided partial protection against death (27 to 36%) and a prolonged time to death compared to results for the mock-vaccinated group. In contrast, LVS and the ΔfipB strain both prolonged the time to death, but there were no survivors from the challenge. This is the first demonstration of vaccine efficacy against aerosol challenge with virulent type A F. tularensis in a species other than a rodent since the original work with LVS in the 1960s. The ΔguaBA and ΔaroD SCHU S4 derivatives warrant further evaluation and consideration as potential vaccines for tularemia and for identification of immunological correlates of protection. PMID:24614653

  13. Deletion of the znuA virulence factor attenuates Actinobacillus pleuropneumoniae and confers protection against homologous or heterologous strain challenge.

    Science.gov (United States)

    Yuan, Fangyan; Liao, Yonghong; You, Wujin; Liu, Zewen; Tan, Yongqiang; Zheng, Chengkun; BinWang; Zhou, Danna; Tian, Yongxiang; Bei, Weicheng

    2014-12-05

    The znuA gene is known to be important for growth and survival in Escherichia coli, Haemophilus spp., Neisseria gonorrhoeae, and Pasteurella multocida under low Zn(2+) conditions. This gene is also present in Actinobacillus pleuropneumoniae serotype 1; therefore, the aim of this study was to investigate the existence of a similar role for the znuA gene in the growth and virulence of this organism. A precisely defined ΔznuA deletion mutant of A. pleuropneumoniae was constructed based on the sequence of the wild-type SLW01 using transconjugation and counterselection. This mutation was found to be lethal in low-Zn(2+) medium. Furthermore, the ΔznuA mutant strain exhibited attenuated virulence (≥22-fold) as well as reduced mortality and morbidity in a murine (Balb/C) model of infection. The majority of the bacteria were cleared from the lungs within 2 weeks. The ΔznuA mutant strain caused no adverse effects in pigs at doses of up to 1.0×10(9) CFU/mL. The ΔznuA mutant strain induced a significant immune response and conferred 80% and 100% protection on immunised pigs against challenge with A. pleuropneumoniae strains belonging to homologous or heterologous serovars, respectively, compared to the blank controls. The data obtained in this study indicate the potential of the mutant ΔznuA strain for development as a live vaccine capable of inducing reliable cross-serovar protection following intratracheal immunisation. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Biofilm formation by asymptomatic and virulent urinary tract infectious Escherichia coli strains

    DEFF Research Database (Denmark)

    Hancock, Viktoria; Ferrieres, Lionel; Klemm, Per

    2007-01-01

    have investigated the biofilm-forming capacity on abiotic surfaces of groups of ABU strains and UPEC strains in human urine. We found that there is a strong bias; ABU strains were significantly better biofilm formers than UPEC strains. Our data suggest that biofilm formation in urinary tract infectious...

  15. reaction of rice cultivars to a virulent rice yellow mottle virus strain

    African Journals Online (AJOL)

    Prof. Adipala Ekwamu

    Nonetheless, emerging diseases such as the Rice Yellow Mottle Virus sobemovirus (RYMV) undermine dissemination of new ... cultivars de riz au virus virulent de la panachure jaune en Ouganda était déterminée. Quatre variétés NERICA de ..... Kouassi, N.K., N'Guessan, P., Albar, L., Fauquet,. C.M. and Brugidou, C. 2005.

  16. Differences in Virulence Markers between Helicobacter pylori Strains from Iraq and Those from Iran: Potential Importance of Regional Differences in H. pylori-Associated Disease▿

    Science.gov (United States)

    Hussein, Nawfal R.; Mohammadi, Marjan; Talebkhan, Yeganeh; Doraghi, Masoumeh; Letley, Darren P.; Muhammad, Merdan K.; Argent, Richard H.; Atherton, John C.

    2008-01-01

    Helicobacter pylori causes peptic ulceration and gastric adenocarcinoma; the latter is common in Iran but not in Iraq. We hypothesized that more virulent H. pylori strains may be found in Iran than in Iraq and so compared established and newly described virulence factors in strains from these countries. We studied 59 unselected dyspeptic patients from Iran and 49 from Iraq. cagA was found in similar proportions of strains from both countries (76% in Iran versus 71% in Iraq) and was significantly associated with peptic ulcer disease in Iraq (P ≤ 0.01) but not in Iran. cagA alleles encoding four or more tyrosine phosphorylation motifs were found in 12% of the Iranian strains but none of the Iraqi strains (P = 0.02). There were no significant differences in the vacA signal-, middle-, or intermediate-region types between Iranian and Iraqi strains. Among the strains from Iran, vacA genotypes showed no specific peptic ulcer associations, but among the strains from Iraq, vacA i1 strains were associated with gastric ulcer (P ≤ 0.02), mimicking their previously demonstrated association with gastric cancer in Iran. dupA was found in similar proportions of Iranian and Iraqi strains (38% and 32%, respectively) and was associated with peptic ulceration in Iraqi patients (P ≤ 0.01) but not Iranian patients. H. pylori strains from Iraq and Iran possess virulence factors similar to those in Western countries. The presence of cagA with more phosphorylation motifs in Iranian strains may contribute to the higher incidence of gastric cancer. However, the association between strain virulence markers and disease in Iraq but not Iran suggests that other host and environmental factors may be more important in the disease-prone Iranian population. PMID:18353934

  17. Genetic virulence profile of enteroaggregative Escherichia coli strains isolated from Danish children with either acute or persistent diarrhea

    DEFF Research Database (Denmark)

    Jensen, Betina Hebbelstrup; Poulsen, Anja; Rasmussen, Stig Hebbelstrup Rye

    2017-01-01

    targeting the genes sat, sepA, pic, sigA, pet, astA, aatA, aggR, aaiC, aap, agg3/4C, ORF3, aafA, aggA, agg3A, agg4A, and agg5A. Furthermore, the distribution of EAEC genes in strains collected from cases of bloody, mucoid, and watery diarrhea was investigated. The classification and regression tree analysis...... (CART) was applied to investigate the relationship between EAEC virulence genes and diarrheal duration and type. Persistent diarrhea was associated with strains lacking the pic gene (p = 0.002) and with the combination of the genes pic, sat, and absence of the aggA gene (p = 0.05). Prolonged diarrhea...

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

    Directory of Open Access Journals (Sweden)

    Faham eKhamesipour

    2014-10-01

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

  19. Comparative analysis of conventional natural killer cell responses to acute infection with Toxoplasma gondii strains of different virulence

    Directory of Open Access Journals (Sweden)

    Daria L Ivanova

    2016-09-01

    Full Text Available Conventional Natural Killer Cells (cNK, members of group 1 innate lymphoid cells, are a diverse cell subpopulation based on surface receptor expression, maturation and functional potential. cNK cells are critical for early immunity to T. gondii via IFNγ production. Acute cNK cell responses to infection with different strains of T. gondii have not yet been characterized in detail. Here we comprehensively performed this analysis with Type I virulent RH, and Type II avirulent ME49 and fully attenuated Type I cps1-1 strains. In response to these three parasite strains, murine cNK cells produce IFNγ, become cytotoxic and polyfunctional (IFNγ+CD107a+ at the site of infection. In contrast to virulent RH and avirulent ME49 T. gondii strains, attenuated cps1-1 induced only local cNK cell responses. Infections with RH and ME49 parasites significantly decreased cNK cell frequency and numbers in spleen 5 days post infection compared to cps1-1 parasites. cNK cell subsets expressing activating receptors Ly49H, Ly49D, NKG2D and inhibitory receptors Ly49I and NKG2A/CD94 were similar when compared between the strains and at 5 days post infection. cNK cells were not proliferating (Ki67- 5 days post infection with any of the strains. cNK cell maturation as measured by CD27, CD11b and KLRG1 was affected after infection with different parasite strains. RH and ME49 infection significantly reduced mature cNK cell frequency and increased immature cNK cell populations compared to cps1-1 infection. Interestingly, KLRG1 was highly expressed on immature cNK cells after RH infection. After RH and ME49 infections, CD69+ cNK cells were present at higher numbers than after cps1-1 infection, which may correlate with loss of the mature cNK cell population. Cytokine multiplex analysis indicated cNK cell responses correlated with peritoneal exudate cell (PEC, spleen and serum proinflammatory cytokine levels including IL-12. qPCR analysis of parasite-specific B1 gene revealed

  20. Strain dependent expression of stress response and virulence genes of Listeria monocytogenes in meat juices as determined by microarray.

    Science.gov (United States)

    Rantsiou, Kalliopi; Greppi, Anna; Garosi, Matteo; Acquadro, Alberto; Mataragas, Marios; Cocolin, Luca

    2012-01-16

    A subgenomic array, encompassing 54 probes targeting genes responsible for virulence, adhesion and stress response in Listeria monocytogenes, was used in order to study their expression in food systems. RNA extracted from L. monocytogenes inoculated in BHI and in situ (i.e. in minced meat and fermented sausage juices) and incubated at 4°C, was hybridized on the array and the results obtained were compared in order to understand the effect that the food juice has on the expression. Three different strains of L. monocytogenes were tested, in order to determine the effect of the strain provenience. As determined by cluster analysis, each strain behaved in a different way when inoculated in food juices. The goal was to respond to acidic and osmotic stresses encountered in the food, particularly in the fermented sausage juice. No differences in the expression profile between the three strains were observed, when they were inoculated in BHI. On the other hand, in the meat and sausage juices, the iap, gadC and gadE genes, together with different internalin encoding genes, were significantly differentially expressed in the three strains. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Identification of genomic islands in Chilean Piscirickettsia salmonis strains and analysis of gene expression involved in virulence.

    Science.gov (United States)

    Lagos, F; Cartes, C; Vera, T; Haussmann, D; Figueroa, J

    2017-10-01

    Piscirickettsia salmonis, an agent of Piscirickettsiosis, is the cause of major losses in the Chilean salmon industry. We identified, characterized and bioinformatically analysed genomic islands in field strains of P. Salmonis, using the bioinformatic software PIPS, that uses the characteristics of the islands of pathogenicity to identify them. We analysed nine partially sequenced genomes in different new field strains, and compared them with the LF-89 (Type strain) genome, selecting a genomic island present in all of them. We then evaluated the relative expression of three genes present in that island. From the obtained results, we conclude that the expression of the tcf gene is directly proportional to the cytopathogenicity in vitro of the bacteria; the product of the dnsa gene could contribute to its pathogenicity, but would be potentiated by one or more factors. The product of the gene liso is necessary for the virulence process and could have functions in early stages of infection. Regarding the strains, the IBM-040 strain showed a significant increase in the expression of all the genes in the study. Contrarily, LF-89 only presented a significant increase in expression of the gene liso, which correlates with the cytopathogenicity in vitro observed in the SHK-1 cells. © 2017 John Wiley & Sons Ltd.

  2. Identification of resistance and virulence factors in an epidemic Enterobacter hormaechei outbreak strain

    NARCIS (Netherlands)

    Paauw, A.; Caspers, M.P.M.; Leverstein-van Hall, M.A.; Schuren, F.H.J.; Montijn, R.C.; Verhoef, J.; Fluit, A.C.

    2009-01-01

    Bacterial strains differ in their ability to cause hospital outbreaks. Using comparative genomic hybridization, Enterobacter cloacae complex isolates were studied to identify genetic markers specific for Enterobacter cloacae complex outbreak strains. No outbreak-specific genes were found that were

  3. Virulence of ’Entamoeba histolytica’ According to the Strains in Korea.

    Science.gov (United States)

    Investigations are reported on the adaptation of Entamoeba histolytica strains to low temperature conditions. Nine strains of E. histolytica which...Electron microscopy of Entamoeba histolytica in culture and in intestinal mucosa are described. The ultrastructural differences among E. histolytica

  4. Genome-Wide Association Studies of Virulent and Avirulent Haemophilus parasuis Serotype 4 Strains

    OpenAIRE

    Lawrence, Paulraj K.; Wiener, Brittanny L.; Kolander-Bremer, Tammy; Bey, Russell F.; Stine, Douglas L.; Kittichotirat, Weerayuth; Bumgarner, Roger E.

    2014-01-01

    Haemophilus parasuis is a normal commensal of the upper respiratory tract of healthy pigs. However, in conjunction with stress and/or viral infections, or in immunocompromised animals, H. parasuis can transform into a pathogen causing Glasser’s disease, which is typically characterized by fibrinous polyserositis, polyarthritis, meningitis, and sometimes acute pneumonia and septicemia. H. parasuis serotype 5 is highly virulent and more frequently isolated from respiratory and systemic infectio...

  5. The secreted autotransporter toxin (Sat) does not act as a virulence factor in the probiotic Escherichia coli strain Nissle 1917.

    Science.gov (United States)

    Toloza, Lorena; Giménez, Rosa; Fábrega, María Jose; Alvarez, Carina Shianya; Aguilera, Laura; Cañas, María Alexandra; Martín-Venegas, Raquel; Badia, Josefa; Baldomà, Laura

    2015-10-30

    Escherichia coli Nissle 1917 (EcN) is a probiotic used in the treatment of intestinal diseases. Although it is considered safe, EcN is closely related to the uropathogenic E. coli strain CFT073 and contains many of its predicted virulence elements. Thus, it is relevant to assess whether virulence-associated genes are functional in EcN. One of these genes encodes the secreted autotransporter toxin (Sat), a member of the serine protease autotransporters of Enterobacteriaceae (SPATEs) that are secreted following the type V autotransporter pathway. Sat is highly prevalent in certain E. coli pathogenic groups responsible for urinary and intestinal infections. In these pathogens Sat promotes cytotoxic effects in several lines of undifferentiated epithelial cells, but not in differentiated Caco-2 cells. Here we provide evidence that sat is expressed by EcN during the colonization of mouse intestine. The EcN protein is secreted as an active serine protease, with its 107 kDa-passenger domain released into the medium as a soluble protein. Expression of recombinant EcN Sat protein in strain HB101 increases paracellular permeability to mannitol in polarized Caco-2 monolayers. This effect, also reported for the Sat protein of diffusely adherent E. coli, is not observed when this protein is expressed in the EcN background. In addition, we show that EcN supernatants confer protection against Sat-mediated effects on paracellular permeability, thus indicating that other secreted EcN factors are able to prevent barrier disruption caused by pathogen-related factors. Sat is not required for intestinal colonization, but the EcNsat::cat mutant outcompetes wild-type EcN in the streptomycin-treated mouse model. Analysis of the presence of sat in 29 strains of the ECOR collection isolated from stools of healthy humans shows 34.8 % positives, with high prevalence of strains of the phylogenetic groups D and B2, related with extra-intestinal infections. Sat does not act as a virulence factor

  6. Vaccination reduces macrophage infiltration in bronchus-associated lymphoid tissue in pigs infected with a highly virulent Mycoplasma hyopneumoniae strain

    Directory of Open Access Journals (Sweden)

    Vranckx Katleen

    2012-03-01

    Full Text Available Abstract Background Mycoplasma hyopneumoniae is the causative agent of enzootic pneumonia and is responsible for significant economic losses to the pig industry. To better understand the mode of action of a commercial, adjuvanted, inactivated whole cell vaccine and the influence of diversity on the efficacy of vaccination, we investigated samples from vaccinated and non-vaccinated pigs experimentally infected with either a low (LV or a highly virulent (HV M. hyopneumoniae strain. Non-vaccinated and sham-infected control groups were included. Lung tissue samples collected at 4 and 8 weeks post infection (PI were immunohistochemically tested for the presence of T-lymphocytes, B-lymphocytes and macrophages in the bronchus-associated lymphoid tissue (BALT. The number of M. hyopneumoniae organisms in bronchoalveolar lavage (BAL fluid was determined using quantitative PCR at 4 and 8 weeks PI. Serum antibodies against M. hyopneumoniae were determined at 0, 2, 4, 6 and 8 weeks PI. Results The immunostaining revealed a lower density of macrophages in the BALT of the vaccinated groups compared to the non-vaccinated groups. The highest number of M. hyopneumoniae organisms in the BAL fluid was measured at 4 weeks PI for the HV strain and at 8 weeks PI for the LV strain. Vaccination reduced the number of organisms non-significantly, though for the HV strain the reduction was clinically more relevant than for the LV strain. At the level of the individual pigs, a higher lung lesion score was associated with more M. hyopneumoniae organisms in the lungs and a higher density of the investigated immune cells in the BALT. Conclusions In conclusion, the infiltration of macrophages after infection with M. hyopneumoniae is reduced by vaccination. The M. hyopneumoniae replication in the lungs is also reduced in vaccinated pigs, though the HV strain is inhibited more than the LV strain.

  7. Vaccination reduces macrophage infiltration in bronchus-associated lymphoid tissue in pigs infected with a highly virulent Mycoplasma hyopneumoniae strain.

    Science.gov (United States)

    Vranckx, Katleen; Maes, Dominiek; Marchioro, Silvana B; Villarreal, Iris; Chiers, Koen; Pasmans, Frank; Haesebrouck, Freddy

    2012-03-12

    Mycoplasma hyopneumoniae is the causative agent of enzootic pneumonia and is responsible for significant economic losses to the pig industry. To better understand the mode of action of a commercial, adjuvanted, inactivated whole cell vaccine and the influence of diversity on the efficacy of vaccination, we investigated samples from vaccinated and non-vaccinated pigs experimentally infected with either a low (LV) or a highly virulent (HV) M. hyopneumoniae strain. Non-vaccinated and sham-infected control groups were included. Lung tissue samples collected at 4 and 8 weeks post infection (PI) were immunohistochemically tested for the presence of T-lymphocytes, B-lymphocytes and macrophages in the bronchus-associated lymphoid tissue (BALT). The number of M. hyopneumoniae organisms in bronchoalveolar lavage (BAL) fluid was determined using quantitative PCR at 4 and 8 weeks PI. Serum antibodies against M. hyopneumoniae were determined at 0, 2, 4, 6 and 8 weeks PI. The immunostaining revealed a lower density of macrophages in the BALT of the vaccinated groups compared to the non-vaccinated groups. The highest number of M. hyopneumoniae organisms in the BAL fluid was measured at 4 weeks PI for the HV strain and at 8 weeks PI for the LV strain. Vaccination reduced the number of organisms non-significantly, though for the HV strain the reduction was clinically more relevant than for the LV strain. At the level of the individual pigs, a higher lung lesion score was associated with more M. hyopneumoniae organisms in the lungs and a higher density of the investigated immune cells in the BALT. In conclusion, the infiltration of macrophages after infection with M. hyopneumoniae is reduced by vaccination. The M. hyopneumoniae replication in the lungs is also reduced in vaccinated pigs, though the HV strain is inhibited more than the LV strain.

  8. Prophage Rs551 and Its Repressor Gene orf14 Reduce Virulence and Increase Competitive Fitness of Its Ralstonia solanacearum Carrier Strain UW551

    Directory of Open Access Journals (Sweden)

    Abdelmonim Ali Ahmad

    2017-12-01

    Full Text Available We previously characterized a filamentous lysogenic bacteriophage, ϕRs551, isolated directly from the race 3 biovar 2 phylotype IIB sequevar 1 strain UW551 of Ralstonia solanacearum grown under normal culture conditions. The genome of ϕRs551 was identified with 100% identity in the deposited genomes of 11 race 3 biovar 2 phylotype IIB sequevar 1 strains of R. solanacearum, indicating evolutionary and biological importance, and ORF14 of ϕRs551 was annotated as a putative type-2 repressor. In this study, we determined the effect of the prophage and its ORF14 on the virulence and competitive fitness of its carrier strain UW551 by deleting the orf14 gene only (the UW551 orf14 mutant, and nine of the prophage’s 14 genes including orf14 and six out of seven structural genes (the UW551 prophage mutant, respectively, from the genome of UW551. The two mutants were increased in extracellular polysaccharide production, twitching motility, expression of targeted virulence and virulence regulatory genes (pilT, egl, pehC, hrPB, and phcA, and virulence, suggesting that the virulence of UW551 was negatively regulated by ϕRs551, at least partially through ORF14. Interestingly, we found that the wt ϕRs551-carrying strain UW551 of R. solanacearum significantly outcompeted the wt strain RUN302 which lacks the prophage in tomato plants co-inoculated with the two strains. When each of the two mutant strains was co-inoculated with RUN302, however, the mutants were significantly out-competed by RUN302 for the same colonization site. Our results suggest that ecologically, ϕRs551 may play an important role by regulating the virulence of and offering a competitive fitness advantage to its carrier bacterial strain for persistence of the bacterium in the environment, which in turn prolongs the symbiotic relationship between the phage ϕRs551 and the R. solanacearum strain UW551. Our study is the first toward a better understanding of the co-existence between a

  9. Identification of gyrB and rpoB gene mutations and differentially expressed proteins between a novobiocin-resistant Aeromonas hydrophila catfish vaccine strain and its virulent parent strain

    Science.gov (United States)

    Sequence comparison between the full-length 2412 bp DNA gyrase subunit B (gyrB) gene of a novobiocin resistant Aeromonas hydrophila AH11NOVO vaccine strain and that of its virulent parent strain AH11P revealed 10 missense mutations. Similarly, sequence comparison between the full-length 4092 bp RNA ...

  10. Live Brucella abortus rough vaccine strain RB51 stimulates enhanced innate immune response in vitro compared to rough vaccine strain RB51SOD and virulent smooth strain 2308 in murine bone marrow-derived dendritic cells.

    Science.gov (United States)

    Surendran, Naveen; Hiltbold, Elizabeth M; Heid, Bettina; Sriranganathan, Nammalwar; Boyle, Stephen M; Zimmerman, Kurt L; Makris, Melissa R; Witonsky, Sharon G

    2011-01-10

    Brucella spp. are Gram-negative, coccobacillary, facultative intracellular pathogens. B. abortus strain 2308 is a pathogenic strain affecting cattle and humans. Rough B. abortus strain RB51, which lacks the O-side chain of lipopolysaccharide (LPS), is the live attenuated USDA approved vaccine for cattle in the United States. Strain RB51SOD, which overexpresses Cu-Zn superoxide dismutase (SOD), has been shown to confer better protection than strain RB51 in a murine model. Protection against brucellosis is mediated by a strong CD4+ Th(1) and CD8+ Tc(1) adaptive immune response. In order to stimulate a robust adaptive response, a solid innate immune response, including that mediated by dendritic cells, is essential. As dendritic cells (DCs) are highly susceptible to Brucella infection, it is possible that pathogenic strains could limit the innate and thereby adaptive immune response. By contrast, vaccine strains could limit or bolster the innate and subsequent adaptive immune response. Identifying how Brucella vaccines stimulate innate and adaptive immunity is critical for enhancing vaccine efficacy. The ability of rough vaccine strains RB51 and RB51SOD to stimulate DC function has not been characterized. We report that live rough vaccine strain RB51 induced significantly better (p ≤ 0.05) DC maturation and function compared to either strain RB51SOD or smooth virulent strain 2308, based on costimulatory marker expression and cytokine production. Copyright © 2010. Published by Elsevier B.V.

  11. The highly virulent 2006 Norwegian EHEC O103:H25 outbreak strain is related to the 2011 German O104:H4 outbreak strain.

    Directory of Open Access Journals (Sweden)

    Trine M L'Abée-Lund

    Full Text Available In 2006, a severe foodborne EHEC outbreak occured in Norway. Seventeen cases were recorded and the HUS frequency was 60%. The causative strain, Esherichia coli O103:H25, is considered to be particularly virulent. Sequencing of the outbreak strain revealed resemblance to the 2011 German outbreak strain E. coli O104:H4, both in genome and Shiga toxin 2-encoding (Stx2 phage sequence. The nucleotide identity between the Stx2 phages from the Norwegian and German outbreak strains was 90%. During the 2006 outbreak, stx(2-positive O103:H25 E. coli was isolated from two patients. All the other outbreak associated isolates, including all food isolates, were stx-negative, and carried a different phage replacing the Stx2 phage. This phage was of similar size to the Stx2 phage, but had a distinctive early phage region and no stx gene. The sequence of the early region of this phage was not retrieved from the bacterial host genome, and the origin of the phage is unknown. The contaminated food most likely contained a mixture of E. coli O103:H25 cells with either one of the phages.

  12. Transplacental transmission of Toxoplasma gondii in minipigs infected with strains of different virulence

    DEFF Research Database (Denmark)

    Jungersen, Gregers; Bille-Hansen, Vivi; Jensen, Lene Bai

    2001-01-01

    inoculated into pregnant minipig gilts. Two strains caused abortions of uninfected fetuses following severe disease of the mothers. One strain caused no disease in the gilts but slightly elevated anti-T. gondii antibodies in 2 of 9 fetuses. One strain produced clinical disease with 4 mummified fetuses and 2...... full-term, congenitally infected piglets in 1 gilt and no clinical disease but elevated specific fetal antibodies in both piglets of the other gilt. Infection with the fifth strain (SVS-O14), which was considered apathogenic to both pigs and mice based on the clinical course of this and previous...

  13. Genomic characterization of Haemophilus parasuis SH0165, a highly virulent strain of serovar 5 prevalent in China.

    Directory of Open Access Journals (Sweden)

    Zhuofei Xu

    Full Text Available Haemophilus parasuis can be either a commensal bacterium of the porcine respiratory tract or an opportunistic pathogen causing Glässer's disease, a severe systemic disease that has led to significant economical losses in the pig industry worldwide. We determined the complete genomic sequence of H. parasuis SH0165, a highly virulent strain of serovar 5, which was isolated from a hog pen in North China. The single circular chromosome was 2,269,156 base pairs in length and contained 2,031 protein-coding genes. Together with the full spectrum of genes detected by the analysis of metabolic pathways, we confirmed that H. parasuis generates ATP via both fermentation and respiration, and possesses an intact TCA cycle for anabolism. In addition to possessing the complete pathway essential for the biosynthesis of heme, this pathogen was also found to be well-equipped with different iron acquisition systems, such as the TonB system and ABC-type transport complexes, to overcome iron limitation during infection and persistence. We identified a number of genes encoding potential virulence factors, such as type IV fimbriae and surface polysaccharides. Analysis of the genome confirmed that H. parasuis is naturally competent, as genes related to DNA uptake are present. A nine-mer DNA uptake signal sequence (ACAAGCGGT, identical to that found in Actinobacillus pleuropneumoniae and Mannheimia haemolytica, followed by similar downstream motifs, was identified in the SH0165 genome. Genomic and phylogenetic comparisons with other Pasteurellaceae species further indicated that H. parasuis was closely related to another swine pathogenic bacteria A. pleuropneumoniae. The comprehensive genetic analysis presented here provides a foundation for future research on the metabolism, natural competence and virulence of H. parasuis.

  14. Genomic Characterization of Haemophilus parasuis SH0165, a Highly Virulent Strain of Serovar 5 Prevalent in China

    Science.gov (United States)

    Zhou, Rui; Jin, Qi; Fan, Yang; Bei, Weicheng; Chen, Huanchun

    2011-01-01

    Haemophilus parasuis can be either a commensal bacterium of the porcine respiratory tract or an opportunistic pathogen causing Glässer's disease, a severe systemic disease that has led to significant economical losses in the pig industry worldwide. We determined the complete genomic sequence of H. parasuis SH0165, a highly virulent strain of serovar 5, which was isolated from a hog pen in North China. The single circular chromosome was 2,269,156 base pairs in length and contained 2,031 protein-coding genes. Together with the full spectrum of genes detected by the analysis of metabolic pathways, we confirmed that H. parasuis generates ATP via both fermentation and respiration, and possesses an intact TCA cycle for anabolism. In addition to possessing the complete pathway essential for the biosynthesis of heme, this pathogen was also found to be well-equipped with different iron acquisition systems, such as the TonB system and ABC-type transport complexes, to overcome iron limitation during infection and persistence. We identified a number of genes encoding potential virulence factors, such as type IV fimbriae and surface polysaccharides. Analysis of the genome confirmed that H. parasuis is naturally competent, as genes related to DNA uptake are present. A nine-mer DNA uptake signal sequence (ACAAGCGGT), identical to that found in Actinobacillus pleuropneumoniae and Mannheimia haemolytica, followed by similar downstream motifs, was identified in the SH0165 genome. Genomic and phylogenetic comparisons with other Pasteurellaceae species further indicated that H. parasuis was closely related to another swine pathogenic bacteria A. pleuropneumoniae. The comprehensive genetic analysis presented here provides a foundation for future research on the metabolism, natural competence and virulence of H. parasuis. PMID:21611187

  15. Determination of resistance and virulence genes in Enterococcus faecalis and E. faecium strains isolated from poultry and their genotypic characterization by ADSRRS-fingerprinting.

    Science.gov (United States)

    Nowakiewicz, A; Ziólkowska, G; Troscianczyk, A; Zieba, P; Gnat, S

    2017-04-01

    The aim of this study was to determine the antimicrobial resistance of E. faecalis and E. faecium strains isolated from poultry and to carry out genotypic characterization thereof with the ADSRRS-fingerprinting method (amplification of DNA fragments surrounding rare restriction sites) and analysis of the genetic relatedness between the isolates with different resistance and virulence determinants. Samples were collected from 70 4-week-old chickens and tested for Enterococcus. Minimum inhibitory concentrations of 11 antimicrobials were determined using the broth microdilution method. Detection of antibiotic resistance and virulence genes was performed using PCR, and molecular analysis was carried out using the ADSRRS-fingerprinting method. The highest percentage of strains was resistant to tetracycline (60.5%) and erythromycin (54.4%), and a large number exhibited high-level resistance to both kanamycin (42.1%) and streptomycin (34.2%). Among 8 genes encoding AME, the tested strains showed mainly the presence of [aph(3΄)-IIIa], [ant(6)-Ia], [aac(6΄)-Ie-aph(2΄΄)-Ia], and [ant(9)-Ia] genes. Phenotypic resistance to erythromycin was encoded in 98.4% strains by the ermB gene. Genotypic resistance to tetracycline in E. faecium was associated with the presence of tetM and tetL (respectively, in 95.5 and 57.7% of the isolates); in contrast, E. faecalis strains were characterized mainly by the presence of tetO (83.3%). The virulence profile was homogenous for all E. faecium strains and included only efaAfm and ccf genes. All E. faecalis strains exhibited efaAfs, gelE, and genes encoding sex pheromones. The strains tested exhibited 34 genotypic profiles. Comparative analysis of phenotypic and genotypic resistance and virulence profiles and confrontation thereof with the genotypes of the strains tested showed that strains assigned to a particular genotype have an identical phenotypic resistance profile and a panel of resistance and virulence genes. The results of this

  16. Virulence factors, antibiotic resistance phenotypes and O-serogroups of Escherichia coli strains isolated from community-acquired urinary tract infection patients in Mexico.

    Science.gov (United States)

    Paniagua-Contreras, Gloria Luz; Monroy-Pérez, Eric; Rodríguez-Moctezuma, José Raymundo; Domínguez-Trejo, Pablo; Vaca-Paniagua, Felipe; Vaca, Sergio

    2017-08-01

    Uropathogenic Escherichia coli (UPEC) strains isolated from patients with community-acquired urinary tract infections (UTIs) were assessed to determine the prevalence of virulence genes, antibiotic resistance, and the O-serogroup of the strains. Consenting patients with community-acquired UTI were enrolled at Unidad Médica Familiar Number 64 (Instituto Mexicano del Seguro Social, Estado de Mexico, Mexico) and 321 urine samples were collected. Polymerase chain reaction (PCR) was used to assess 24 virulence genes and 14 O-serogroups. The Kirby-Bauer method was used to evaluate the antibiotic susceptibility of the isolated strains to 12 commonly used antibiotics. A total of 194 strains were identified as E. coli using standard biochemical tests, followed by PCR amplification of 16S ribosomal RNA gene. Only 58.2% of the strains belonged to the assessed 14 O-serogroups. The serogroups O25, O15, O8, and O75 were present in 20.6%, 17%, 6.1%, and 4.6% of strains, respectively. The most frequently occurring virulence genes among UPEC strains included kpsMT (92.2% strains), usp (87.1%), irp2 (79.3%), iha (64.9%), fim (61.3%), set (36%), astA (33.5%), pap (24.7%), and papGII (21.1%). In addition, 97% of the strains were multi-drug resistant (coresistance to 3-11 antibiotics). The isolated UPEC strains predominantly belonged to three serogroups (O25, O15, and O8), harboured numerous virulence genes, and are multiresistant to antibiotics. The findings of this study could be used to orient UTI treatment strategies and in epidemiological studies in Mexico. Copyright © 2015. Published by Elsevier B.V.

  17. The efficacy of CP7_E2alf: an animal study involving piglets from C–strain vaccinated sows

    DEFF Research Database (Denmark)

    Rangelova, Desislava Yordanova; Nielsen, Jens; Strandbygaard, Bertel

    Outbreaks of Classical Swine Fever (CSF) in the European Union have caused enormous economical losses. To facilitate the possibility of free trade with pigs and their products, a chimeric live DIVA vaccine CP7_E2alf was developed. Most likely, passive immunity against CSF virus in populations...... previously vaccinated with C-strain interferes with the efficacy of CP7_E2alf vaccination. To study the interaction with maternal antibodies, the efficacy of CP7_E2alf in piglets from C-strain vaccinated sows was examined. At 5 or at 8 weeks of age, piglets were vaccinated with CP7_E2alf. The vaccinated...... piglets together with mock-vaccinated littermate controls were challenged 2 weeks post vaccination with highly virulent CSFV Kozlov. The results showed that CP7_E2alf is effective in preventing mortality, severe clinical signs and pathological lesions in piglets vaccinated at 5 or at 8 weeks of age...

  18. Evaluation of the Antibiotic Resistance and Virulence of Escherichia coli Strains Isolated from Chicken Carcasses in 2007 and 2013 from Paraná, Brazil.

    Science.gov (United States)

    Koga, Vanessa L; Rodrigues, Gabriela R; Scandorieiro, Sara; Vespero, Eliana C; Oba, Alexandre; de Brito, Benito G; de Brito, Kelly C T; Nakazato, Gerson; Kobayashi, Renata K T

    2015-06-01

    The frequent use of antimicrobials in commercial poultry production has raised concerns regarding the potential impact of antimicrobials on human health due to selection for resistant bacteria. Several studies have reported similarities between extraintestinal pathogenic Escherichia coli (ExPEC) strains isolated from birds and humans, indicating that these contaminant bacteria in poultry may be linked to human disease. The aim of our study was to analyze the frequency of antimicrobial resistance and virulence factors among E. coli strains isolated from commercial chicken carcasses in Paraná, Brazil, in 2007 and 2013. A total of 84 E. coli strains were isolated from chicken carcasses in 2007, and 121 E. coli strains were isolated in 2013. Polymerase chain reaction was used to detect virulence genes (hlyF, iss, ompT, iron, and iutA) and to determine phylogenetic classification. Antimicrobial susceptibility testing was performed using 15 antimicrobials. The strains were also confirmed as extended-spectrum β-lactamase (ESBL)-producing E. coli with phenotypic and genotypic tests. The results indicated that our strains harbored virulence genes characteristic of ExPEC, with the iutA gene being the most prevalent. The phylogenetic groups D and B1 were the most prevalent among the strains isolated in 2007 and 2013, respectively. There was an increase in the frequency of resistance to a majority of antimicrobials tested. An important finding in this study was the large number of ESBL-producing E. coli strains isolated from chicken carcasses in 2013, primarily for the group 2 cefotaximase (CTX-M) enzyme. ESBL production confers broad-spectrum resistance and is a health risk because ESBL genes are transferable from food-producing animals to humans via poultry meat. These findings suggest that our strains harbored virulence and resistance genes, which are often associated with plasmids that can facilitate their transmission between bacteria derived from different hosts

  19. Exploring Genomic, Geographic and Virulence Interactions among Epidemic and Non-Epidemic St. Louis Encephalitis Virus (Flavivirus Strains.

    Directory of Open Access Journals (Sweden)

    Luis A Diaz

    Full Text Available St. Louis encephalitis virus (SLEV is a re-emerging arbovirus in South America. In 2005, an encephalitis outbreak caused by SLEV was reported in Argentina. The reason for the outbreak remains unknown, but may have been related to virological factors, changes in vectors populations, avian amplifying hosts, and/or environmental conditions. The main goal of this study was to characterize the complete genome of epidemic and non-epidemic SLEV strains from Argentina. Seventeen amino acid changes were detected; ten were non-conservative and located in proteins E, NS1, NS3 and NS5. Phylogenetic analysis showed two major clades based on geography: the North America and northern Central America (NAnCA clade and the South America and southern Central America (SAsCA clade. Interestingly, the presence of SAsCA genotype V SLEV strains in the NAnCA clade was reported in California, Florida and Texas, overlapping with known bird migration flyways. This work represents the first step in understanding the molecular mechanisms underlying virulence and biological variation among SLEV strains.

  20. The importance of Bordetella pertussis strains which do not produce virulence factors in the epidemiology of pertussis

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    Maciej Polak

    2017-05-01

    Full Text Available Bordetella pertussis strains, which have lost the ability to produce antigens, such as pertactin - Prn, pertussis toxin - Ptx, filamentous haemagglutinin - FHA, fimbriae type 2 and 3 - Fim 2 and 3, tracheal colonization factor - TcfA, have recently been isolated in countries with a high vaccination coverage. The emergence of such isolates might have resulted from B. pertussis natural evolution course or adaptive mechanisms, allowing increased circulation of the pathogen in vaccinated populations. So far, the majority of described mutants were deficient in the Prn production. Prn deficient isolates were found in countries which use acellular pertussis vaccines (aP in routine immunization programmes. The increase of frequency of Prn¯ strains isolation was correlated with the period of routine vaccination with aP vaccines. In most countries, the spread of these isolates has resulted from independent mutations rather than from the expansion of a single clone. Prn¯ isolates were collected from patients showing typical clinical symptoms of pertussis found for Prn+ strains. Results of in vitro and in vivo studies have shown that Prn¯, Ptx¯ and FHA¯ isolates retain cytotoxic properties, and besides Ptx¯ isolates, were lethal in intranasally infected mice. Further explanation of the impact of antigen deficiencies on virulence and transmission of B. pertussis in the context of the continuous increase of pertussis incidence is necessary to develop a new, optimized strategy of pertussis prevention.

  1. Staphylococcus epidermidis strains isolated from breast milk of women suffering infectious mastitis: potential virulence traits and resistance to antibiotics.

    Science.gov (United States)

    Delgado, Susana; Arroyo, Rebeca; Jiménez, Esther; Marín, Maria L; del Campo, Rosa; Fernández, Leonides; Rodríguez, Juan M

    2009-05-07

    Although Staphylococcus aureus is considered the main etiological agent of infectious mastitis, recent studies have suggested that coagulase-negative staphylococci (CNS) may also play an important role in such infections. The aims of this work were to isolate staphylococci from milk of women with lactational mastitis, to select and characterize the CNS isolates, and to compare such properties with those displayed by CNS strains isolated from milk of healthy women. The milk of 30 women was collected and bacterial growth was noted in 27 of them, of which Staphylococcus epidermidis was isolated from 26 patients and S. aureus from 8. Among the 270 staphylococcal isolates recovered from milk of women with mastitis, 200 were identified as Staphylococcus epidermidis by phenotypic assays, species-specific PCR and PCR sequencing. They were typified by pulsed field gel electrophoresis (PFGE) genotyping. The PFGE profiles of the S. epidermidis strains were compared with those of 105 isolates from milk of healthy women. A representative of the 76 different PFGE profiles was selected to study the incidence of virulence factors and antibiotic resistance. The number of strains that contained the biofilm-related icaD gene and that showed resistance to oxacillin, erythromycin, clindamycin and mupirocin was significantly higher among the strains isolated from mastitic milk. S. epidermidis may be a frequent but largely underrated cause of infectious mastitis in lactating women. The resistance to diverse antibiotics and a higher ability to form biofilms found among the strains isolated from milk of women suffering mastitis may explain the chronic and/or recurrent nature of this infectious condition.

  2. Staphylococcus epidermidis strains isolated from breast milk of women suffering infectious mastitis: potential virulence traits and resistance to antibiotics

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    Fernández Leonides

    2009-05-01

    Full Text Available Abstract Background Although Staphylococcus aureus is considered the main etiological agent of infectious mastitis, recent studies have suggested that coagulase-negative staphylococci (CNS may also play an important role in such infections. The aims of this work were to isolate staphylococci from milk of women with lactational mastitis, to select and characterize the CNS isolates, and to compare such properties with those displayed by CNS strains isolated from milk of healthy women. Results The milk of 30 women was collected and bacterial growth was noted in 27 of them, of which Staphylococcus epidermidis was isolated from 26 patients and S. aureus from 8. Among the 270 staphylococcal isolates recovered from milk of women with mastitis, 200 were identified as Staphylococcus epidermidis by phenotypic assays, species-specific PCR and PCR sequencing. They were typified by pulsed field gel electrophoresis (PFGE genotyping. The PFGE profiles of the S. epidermidis strains were compared with those of 105 isolates from milk of healthy women. A representative of the 76 different PFGE profiles was selected to study the incidence of virulence factors and antibiotic resistance. The number of strains that contained the biofilm-related icaD gene and that showed resistance to oxacillin, erythromycin, clindamycin and mupirocin was significantly higher among the strains isolated from mastitic milk. Conclusion S. epidermidis may be a frequent but largely underrated cause of infectious mastitis in lactating women. The resistance to diverse antibiotics and a higher ability to form biofilms found among the strains isolated from milk of women suffering mastitis may explain the chronic and/or recurrent nature of this infectious condition.

  3. Virulence factors of Streptococcus pyogenes strains from women in peri-labor with invasive infections.

    Science.gov (United States)

    Golińska, E; van der Linden, M; Więcek, G; Mikołajczyk, D; Machul, A; Samet, A; Piórkowska, A; Dorycka, M; Heczko, P B; Strus, M

    2016-05-01

    Invasive group A streptococcal (GAS) infections constitute an important epidemiological problem. Many cases occur in women during the postnatal period. The objective of this study was to evaluate the presence of the genes responsible for production of iron-chelating protein (perR) and superantigens (speA, speB, speC, speF, speG, speH, speI, speJ, speK, speL, speM, smeZ, and ssa) in S. pyogenes strains isolated from invasive infections in women after delivery. Furthermore, this study sought to verify whether S. pyogenes strains show special phenotypic and genotypic (sla, spy1325) characteristics that may play a decisive role in adherence to the genital tract epithelium. Moreover, the emm-types and antibiotic susceptibility were determined. We tested 30 invasive S. pyogenes strains isolated from postpartum invasive infection and 37 GAS control strains isolated from the genital tracts of asymptomatic multiparous women. The majority of the tested strains were shown to express two types of emm genes (1 and 28), though emm -12, -28, -75 and -89 were uniquely expressed in the group of strains isolated from invasive infections. A significantly higher prevalence of perR in the strains from puerperal fever was shown. Significant differences were also found between the two groups with respect to the incidence of the genes related to adherence; GAS strains originating from women with sepsis/puerperal fever showed presence of these genes less frequently than those of the control group. Although differences in frequencies of the gene coding for various superantigens were noted between the compared groups of GAS strains, they were not significant.

  4. Infection with a Virulent Strain of Wolbachia Disrupts Genome Wide-Patterns of Cytosine Methylation in the Mosquito Aedes aegypti.

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    Yixin H Ye

    Full Text Available Cytosine methylation is one of several reversible epigenetic modifications of DNA that allow a greater flexibility in the relationship between genotype and phenotype. Methylation in the simplest models dampens gene expression by modifying regions of DNA critical for transcription factor binding. The capacity to methylate DNA is variable in the insects due to diverse histories of gene loss and duplication of DNA methylases. Mosquitoes like Drosophila melanogaster possess only a single methylase, DNMT2.Here we characterise the methylome of the mosquito Aedes aegypti and examine its relationship to transcription and test the effects of infection with a virulent strain of the endosymbiont Wolbachia on the stability of methylation patterns.We see that methylation in the A. aegypti genome is associated with reduced transcription and is most common in the promoters of genes relating to regulation of transcription and metabolism. Similar gene classes are also methylated in aphids and honeybees, suggesting either conservation or convergence of methylation patterns. In addition to this evidence of evolutionary stability, we also show that infection with the virulent wMelPop Wolbachia strain induces additional methylation and demethylation events in the genome. While most of these changes seem random with respect to gene function and have no detected effect on transcription, there does appear to be enrichment of genes associated with membrane function. Given that Wolbachia lives within a membrane-bound vacuole of host origin and retains a large number of genes for transporting host amino acids, inorganic ions and ATP despite a severely reduced genome, these changes might represent an evolved strategy for manipulating the host environments for its own gain. Testing for a direct link between these methylation changes and expression, however, will require study across a broader range of developmental stages and tissues with methods that detect splice variants.

  5. Transcriptome analysis of rainbow trout infected with high and low virulence strains of Infectious hematopoietic necrosis virus

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    Purcell, Maureen K.; Marjara, Inderjit Singh; Batts, William; Kurath, Gael; Hansen, John D.

    2010-01-01

    There are three main genetic lineages or genogroups of Infectious hematopoietic necrosis virus (IHNV) in N. America. Strains representing the M genogroup are more virulent in rainbow trout relative to the U genogroup. In this study, we used microarray analysis to evaluate potential mechanisms responsible for host-specific virulence in rainbow trout that were given intraperitoneal injections of buffer or a representative M or U type virus strain. Reverse transcriptase quantitative PCR (RT-qPCR) was used to assess viral load and gene expression of select immune genes. Viral load was significantly higher in trout infected with the M virus starting at 24 h post-infection (p.i.) and continuing until 72 h p.i. Microarray analysis of the 48 h time point revealed 153 up-regulated and 248 down-regulated features in response to M virus infection but only 62 up-regulated and 49 down-regulated features following U virus infection. Translation and transcription features were among the most frequent down-regulated features in response to M virus infection and may be associated with the host cell shutoff phenomenon. A greater host cell shutoff response by the M virus may facilitate subversion of the host cell transcriptional machinery and enhance viral replication, suggesting the M virus may be better optimized to manipulate the rainbow trout transcriptional and translational machinery. Anti-viral associated features were the most commonly up-regulated features. A common set of features were up-regulated in both the M and U infection groups, but were induced to a higher magnitude in the M infection group. Gene expression of the anti-viral genes Mx-1 and Vig-1 was correlated but not entirely dependent on viral load in the anterior kidney. Slower replication of the U virus may allow the host more time to induce protective anti-viral immune mechanisms.

  6. DIVA vaccine properties of the live chimeric pestivirus strain CP7_E2gif.

    Science.gov (United States)

    von Rosen, Tanya; Rangelova, Desislava; Nielsen, Jens; Rasmussen, Thomas Bruun; Uttenthal, Åse

    2014-06-04

    Live modified vaccines to protect against classical swine fever virus (CSFV), based on chimeric pestiviruses, have been developed to enable serological Differentiation of Infected from Vaccinated Animals (DIVA). In this context, the chimeric virus CP7_E2gif vaccine candidate is unique as it does not include any CSFV components. In the present study, the DIVA vaccine properties of CP7_E2gif were evaluated in comparison to the conventional live attenuated Riemser C-strain vaccine. Sera and tonsil samples obtained from pigs immunised with these two vaccines were analysed. No viral RNA was found in serum after vaccination with CP7_E2gif, whereas some serum samples from C-strain vaccinated animals were positive. In both vaccinated groups, individual viral RNA-positive tonsil samples were detected in animals euthanised between 7 and 21 days post vaccination. Furthermore, serum samples from these animals, together with archival samples from pigs vaccinated with CP7_E2gif and subsequently CSFV challenged, were analysed for specific antibodies using ELISAs and for homologous neutralising antibodies. In animals vaccinated with CP7_E2gif, neutralising antibodies were detected from day 10. However, the sera remained negative for anti-CSFV E2-specific antibodies whereas pigs vaccinated with C-strain seroconverted against CSFV by 14 days after vaccination, as determined by a CSFV-E2 specific blocking ELISA. One week after subsequent CSFV challenge, a strong anti-CSFV E2 reaction was detected in CP7_E2gif vaccinated pigs and anti-E(rns) antibodies were detected from 10 days after infection. In conclusion, CP7_E2gif has the potential to be used as a DIVA vaccine in combination with detection of anti-CSFV E2-specific antibodies. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Occurrence of virulence factors and antimicrobial resistance in Pasteurella multocida strains isolated from slaughter cattle in Iran

    Science.gov (United States)

    Khamesipour, Faham; Momtaz, Hassan; Azhdary Mamoreh, Morteza

    2014-01-01

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

  8. Occurrence of virulence factors and antimicrobial resistance in Pasteurella multocida strains isolated from slaughter cattle in Iran.

    Science.gov (United States)

    Khamesipour, Faham; Momtaz, Hassan; Azhdary Mamoreh, Morteza

    2014-01-01

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

  9. Contrasting transcriptional responses of a virulent and an attenuated strain of Mycobacterium tuberculosis infecting macrophages.

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    Alice H Li

    2010-06-01

    Full Text Available H37Rv and H37Ra are well-described laboratory strains of Mycobacterium tuberculosis derived from the same parental strain, H37, that show dramatically different pathogenic phenotypes.In this study, the transcriptomes of the two strains during axenic growth in broth and during intracellular growth within murine bone-marrow macrophages were compared by whole genome expression profiling. We identified and compared adaptations of either strain upon encountering an intracellular environment, and also contrasted the transcriptomes of the two strains while inside macrophages. In the former comparison, both strains induced genes that would facilitate intracellular survival including those involved in mycobactin synthesis and fatty acid metabolism. However, this response was stronger and more extensive for H37Rv than for H37Ra. This was manifested as the differential expression of a greater number of genes and an increased magnitude of expression for these genes in H37Rv. In comparing intracellular transcriptional signatures, fifty genes were found to be differentially expressed between the strains. Of these fifty, twelve were under control of the PhoPR regulon. Further differences between strains included genes whose products were members of the ESAT-6 family of proteins, or were associated with their secretion.Along with the recent identification of single nucleotide polymorphisms in H37Ra when compared to H37Rv, our demonstration of differential expression of PhoP-regulated and ESX-1 region-related genes during macrophage infection further highlights the significance of these genes in the attenuation of H37Ra.

  10. Frequency of virulence genes in mixed infections with Helicobacter pylori strains from a Mexican population

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    R. González-Vázquez

    2016-01-01

    Conclusions: The Fisher's exact test did not support a significant association between clinical outcome and genotype. The main circulating genotypes in the Mexican population studied were: cagA+, vacAs1, and vacAm1. Multiplex PCR can be used as a screening test for H. pylori strains. Furthermore, the cagE gene is a good marker for identifying cag-PAI positive strains.

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

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    Benito Guimarães de Brito

    2004-04-01

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

  12. Virulence Markers and Phylogenetic Analysis of Escherichia coli Strains with Hybrid EAEC/UPEC Genotypes Recovered from Sporadic Cases of Extraintestinal Infections.

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    Lara, Flaviane B M; Nery, Danielly R; de Oliveira, Pâmela M; Araujo, Mayana L; Carvalho, Fabiana R Q; Messias-Silva, Lorena C F; Ferreira, Leonardo B; Faria-Junior, Celio; Pereira, Alex L

    2017-01-01

    Virulence genes from different E. coli pathotypes are blended in hybrid strains. E. coli strains with hybrid enteroaggregative/uropathogenic (EAEC/UPEC) genotypes have sporadically emerged causing outbreaks of extraintestinal infections, however their association with routine infections is yet underappreciated. We assessed 258 isolates of E. coli recovered from 86 consecutive cases of extraintestinal infections seeking EAEC and hybrid genotype (EAEC/UPEC) strains. Extensive virulence genotyping was carried out to detect 21 virulence genes, including molecular predictors of EAEC and UPEC strains. Phylogenetic groups and sequence types (STs) were identified, as well as it was performed phylogenetic analyses in order to evaluate whether hybrid EAEC/UPEC strains belonged to intestinal or extraintestinal lineages of E. coli. Adhesion assays were performed to evaluate the biofilm formation by hybrid strains in human urine and cell culture medium (DMEM). Molecular predictors of UPEC were detected in more than 70% of the strains (chuA in 85% and fyuA in 78%). Otherwise, molecular predictors of EAEC (aatA and aggR) were detected in only 3.4% (9/258) of the strains and always along with the UPEC predictor fyuA. Additionally, the pyelonephritis-associated pilus (pap) gene was also detected in all of the hybrid EAEC/UPEC strains. EAEC/UPEC strains were recovered from two cases of community-onset urinary tract infections (UTI) and from a case of bacteremia. Analyses revealed that hybrid EAEC/UPEC strains were phylogenetically positioned in two different clades. Two representative strains, each recovered from UTI and bacteremia, were positioned into a characteristic UPEC clade marked by strains belonging to phylogenetic group D and ST3 (Warwick ST 69). Another hybrid EAEC/UPEC strain was classified as phylogroup A-ST478 and positioned in a commensal clade. Hybrid EAEC/UPEC strains formed biofilms at modest, but perceptible levels either in DMEM or in urine samples. We showed

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

    Science.gov (United States)

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

    2015-01-01

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

  14. Relationship between the Antifungal Susceptibility Profile and the Production of Virulence-Related Hydrolytic Enzymes in Brazilian Clinical Strains of Candida glabrata

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    Maria Helena Galdino Figueiredo-Carvalho

    2017-01-01

    Full Text Available Candida glabrata is a facultative intracellular opportunistic fungal pathogen in human infections. Several virulence-associated attributes are involved in its pathogenesis, host-pathogen interactions, modulation of host immune defenses, and regulation of antifungal drug resistance. This study evaluated the in vitro antifungal susceptibility profile to five antifungal agents, the production of seven hydrolytic enzymes related to virulence, and the relationship between these phenotypes in 91 clinical strains of C. glabrata. All C. glabrata strains were susceptible to flucytosine. However, some of these strains showed resistance to amphotericin B (9.9%, fluconazole (15.4%, itraconazole (5.5%, or micafungin (15.4%. Overall, C. glabrata strains were good producers of catalase, aspartic protease, esterase, phytase, and hemolysin. However, caseinase and phospholipase in vitro activities were not detected. Statistically significant correlations were identified between micafungin minimum inhibitory concentration (MIC and esterase production, between fluconazole and micafungin MIC and hemolytic activity, and between amphotericin B MIC and phytase production. These results contribute to clarify some of the C. glabrata mechanisms of pathogenicity. Moreover, the association between some virulence attributes and the regulation of antifungal resistance encourage the development of new therapeutic strategies involving virulence mechanisms as potential targets for effective antifungal drug development for the treatment of C. glabrata infections.

  15. Whole genome sequencing of diverse Shiga toxin-producing and non-producing Escherichia coli strains reveals a variety of virulence and novel antibiotic resistance plasmids.

    Science.gov (United States)

    Losada, Liliana; DebRoy, Chitrita; Radune, Diana; Kim, Maria; Sanka, Ravi; Brinkac, Lauren; Kariyawasam, Subhashinie; Shelton, Daniel; Fratamico, Pina M; Kapur, Vivek; Feng, Peter C H

    2016-01-01

    The genomes of a diverse set of Escherichia coli, including many Shiga toxin-producing strains of various serotypes were determined. A total of 39 plasmids were identified among these strains, and many carried virulence or putative virulence genes of Shiga toxin-producing E. coli strains, virulence genes for other pathogenic E. coli groups, and some had combinations of these genes. Among the novel plasmids identified were eight that carried resistance genes to aminoglycosides, carbapenems, penicillins, cephalosporins, chloramphenicol, dihydrofolate reductase inhibitors, sulfonamides, tetracyclines and resistance to heavy metals. Two of the plasmids carried six of these resistance genes and two novel IncHI2 plasmids were also identified. The results of this study showed that plasmids carrying diverse resistance and virulence genes of various pathogenic E. coli groups can be found in E. coli strains and serotypes regardless of the isolate's source and therefore, is consistent with the premise that these mobile elements carrying these traits may be broadly disseminated among E. coli. Published by Elsevier Inc.

  16. Investigation on prevalence of Escherichia coli strains carrying virulence genes ipaH, estA, eaeA and bfpA isolated from different water sources

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    Reza Ranjbar

    2016-04-01

    Full Text Available Objective: To investigate prevalence of Escherichia coli (E. coli strains carrying virulence genes ipaH, estA, eaeA and bfpA, isolated from different water sources in Alborz Province. Methods: This study was carried out in 2014. The research included all E. coli strains isolated from different surface water sources in Alborz Province of Iran. E. coli isolates were detected and identified by standard microbiological and biochemical tests. The strains were evaluated for the presence of virulence genes ipaH, estA, eaeA and bfpA by PCR using specific primers. The PCR amplicons were visualized via electrophoresis and stained with ethidium bromide. Results: One hundred E. coli strains were isolated and included in the study. The PCR results showed that 97% of the strains harbored ipaH gene. Moreover, estA, eaeA and bfpA genes were found in 37%, 31% and 3% of the isolates. Conclusions: Our finding showed that the prevalence rates of virulence genes ipaH and estA were very high among E. coli strains isolated from different surface water sources in Alborz Province. Considering their plasmid-borne nature, the risk of transmission of these genes between other bacterial species could pose a high threat to public health.

  17. Reversion to virulence evaluation of a 9R vaccine strain of Salmonella enterica serovar gallinarum in commercial brown layers

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    AS Okamoto

    2010-03-01

    Full Text Available The live vaccine Cevac S. Gallinarum, made from a rough strain of Salmonella enterica subspecies enterica serotype Gallinarum is used for preventing fowl typhoid, a disease that still causes considerable economic losses in countries with a developing poultry industry. The objective of this paper was to evaluate a possible reversion to virulence of the strain used in a vaccine in commercial brown layers. Only Salmonella-free chicks were utilized. One hundred twenty (120 12-day-old Dekalb brown layers divided in two trials were used. The first trial had six groups of 15 birds each. Birds of group 1 were vaccinated with 10 doses of Cevac S. Gallinarum subcutaneously and 10 doses orally, in a total of 20 doses of vaccine. Then the birds of groups 2, 3, 4, and 5 received inocula that contained feces and a pool of organs with fragments of liver, heart, spleen, and cecal tonsils obtained from the immediately previous group. The second trial had three groups with 10 birds each. Birds in group 7 received inocula containing a pool of organs from birds of group 5 from trial 1, whilst the birds in group 8 were vaccinated subcutaneously with one dose of vaccine. Both trials included negative control groups (6 and 9. Throughout the experimental period, birds were monitored for reactions to the vaccination on the site of administration, clinical signs, and post-mortem lesions. In each passage, in addition to the birds euthanized to provide the inocula material, two birds from each group were euthanized for assessment of possible lesions, and their organs (liver, heart, spleen and cecal tonsils were cultured in an attempt to isolate the vaccine strain. Except for one bird from group 1, that had a local reaction on the site of vaccination - a small vesicle with less that 0.5 mm that persisted until the third day post vaccination -, no other bird had any local reaction to the vaccine or any visible clinical alteration. Birds in group 8 did not present any

  18. Experimental Infection of Richardson's Ground Squirrels (Spermophilus richardsonii) with Attenuated and Virulent Strains of Brucella abortus

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    Exposure of non-target species to wildlife vaccines is an important concern when evaluating a candidate vaccine for use in the field. A previous investigation of the safety of Brucella abortus strain RB51 (sRB51) in various non-target species suggested that Richardson’s ground squirrels (Spermophil...

  19. Complete genome sequence of a virulent Streptococcus agalactiae strain 138P isolated from diseased Nile tilapia

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    Streptococcus agalactiae strain 138P was isolated from the kidney of diseased Nile tilapia in Idaho during a 2007 streptococcal disease outbreak. The full genome of S. agalactiae 138P is 1,838,716 bp. The availability of this genome will allow comparative genomics to identify genes for antigen disco...

  20. Antimicrobial resistance and virulence traits in Enterococcus strains isolated from dogs and cats.

    Science.gov (United States)

    Iseppi, Ramona; Messi, Patrizia; Anacarso, Imacolata; Bondi, Moreno; Sabia, Carla; Condò, Carla; de Niederhausern, Simona

    2015-07-01

    We investigated presence and prevalence of antibiotic-resistances and other biological characters in enterococci isolated from faeces of healthy dogs and cats because these microorganisms represent important human and veterinary pathogens/opportunists, and a significant burden for healthcare systems. In all samples (n=115) we detected enterococci, with a predominance of Enterococcus faecium (42; 36.5%) and Enterococcus faecalis (36; 31.3%) species, endowed with virulence traits and multidrug-resistance. The two predominant resistance patterns (erythromycin, tetracycline) were examined by polymerase chain reaction for tet and erm genes. Only tetM for tetracycline, and ermA and ermB for erythromycin were detected. PCR for gelatinase gene (gelE) was positive in 62.6% of isolates, but only 26.1% produce gelatinase suggesting the existence of silent genes. efaAfs and efaAfm genes were found in E. faecalis and E. faecium respectively. 89.6% of isolates produced bacteriocin-like substances with a prevailing action against Listeria genus and, among these, 33.9% were positive for the bacteriocin structural genes entA, entL50 or entP. According to our study, pet animals can be considered a reservoir of potentially pathogenic enterococci and we cannot exclude that those microorganisms may be responsible for opportunistic infections in high-risk pet owners.

  1. Complete Sequence of Virulence Plasmid pJM1 from the Marine Fish Pathogen Vibrio anguillarum Strain 775

    Science.gov (United States)

    Di Lorenzo, Manuela; Stork, Michiel; Tolmasky, Marcelo E.; Actis, Luis A.; Farrell, David; Welch, Timothy J.; Crosa, Lidia M.; Wertheimer, Anne M.; Chen, Qian; Salinas, Patricia; Waldbeser, Lillian; Crosa, Jorge H.

    2003-01-01

    The virulence plasmid pJM1 enables the fish pathogen Vibrio anguillarum, a gram-negative polarly flagellated comma-shaped rod bacterium, to cause a highly fatal hemorrhagic septicemic disease in salmonids and other fishes, leading to epizootics throughout the world. The pJM1 plasmid 65,009-nucleotide sequence, with an overall G+C content of 42.6%, revealed genes and open reading frames (ORFs) encoding iron transporters, nonribosomal peptide enzymes, and other proteins essential for the biosynthesis of the siderophore anguibactin. Of the 59 ORFs, approximately 32% were related to iron metabolic functions. The plasmid pJM1 confers on V. anguillarum the ability to take up ferric iron as a complex with anguibactin from a medium in which iron is chelated by transferrin, ethylenediamine-di(o-hydroxyphenyl-acetic acid), or other iron-chelating compounds. The fatDCBA-angRT operon as well as other downstream biosynthetic genes is bracketed by the homologous ISV-A1 and ISV-A2 insertion sequences. Other clusters on the plasmid also show an insertion element-flanked organization, including ORFs homologous to genes involved in the biosynthesis of 2,3-dihydroxybenzoic acid. Homologues of replication and partition genes are also identified on pJM1 adjacent to this region. ORFs with no known function represent approximately 30% of the pJM1 sequence. The insertion sequence elements in the composite transposon-like structures, corroborated by the G+C content of the pJM1 sequence, suggest a modular composition of plasmid pJM1, biased towards acquisition of modules containing genes related to iron metabolic functions. We also show that there is considerable microheterogeneity in pJM1-like plasmids from virulent strains of V. anguillarum isolated from different geographical sources. PMID:13129954

  2. Cytokine responses in primary chicken embryo intestinal cells infected with Campylobacter jejuni strains of human and chicken origin and the expression of bacterial virulence-associated genes

    DEFF Research Database (Denmark)

    Li, Yiping; Ingmer, Hanne; Madsen, Mogens

    2008-01-01

    -free media from another co-cultivation experiment also increased the expression of the virulence-associated genes in the C. jejuni chicken isolate, indicating that the expression of bacterial genes is regulated by component(s) secreted upon co-cultivation of bacteria and CEICs. Conclusion We show that under...... in vitro culture condition C. jejuni strains of both human and chicken origins can invade avian host cells with a pro-inflammatory response and that the virulence-associated genes of C. jejuni may play a role in this process....

  3. Variable Virulence and Efficacy of BCG Vaccine Strains in Mice and Correlation With Genome Polymorphisms

    OpenAIRE

    Zhang, Lu; Ru, Huan-wei; Chen, Fu-zeng; Jin, Chun-yan; Sun, Rui-feng; Fan, Xiao-yong; Guo, Ming; Mai, Jun-tao; Xu, Wen-xi; Lin, Qing-xia; Liu, Jun

    2016-01-01

    Bacille Calmette?Gu?rin (BCG), an attenuated strain of Mycobacterium bovis, is the only vaccine available for tuberculosis (TB) control. However, BCG is not an ideal vaccine and has two major limitations: BCG exhibits highly variable effectiveness against the development of TB both in pediatric and adult populations and can cause disseminated BCG disease in immunocompromised individuals. BCG comprises a number of substrains that are genetically distinct. Whether and how these genetic differen...

  4. Incremental Contributions of FbaA and Other Impetigo-Associated Surface Proteins to Fitness and Virulence of a Classical Group A Streptococcal Skin Strain.

    Science.gov (United States)

    Rouchon, Candace N; Ly, Anhphan T; Noto, John P; Luo, Feng; Lizano, Sergio; Bessen, Debra E

    2017-11-01

    Group A streptococci (GAS) are highly prevalent human pathogens whose primary ecological niche is the superficial epithelial layers of the throat and/or skin. Many GAS strains with a strong tendency to cause pharyngitis are distinct from strains that tend to cause impetigo; thus, genetic differences between them may confer host tissue-specific virulence. In this study, the FbaA surface protein gene was found to be present in most skin specialist strains but largely absent from a genetically related subset of pharyngitis isolates. In an ΔfbaA mutant constructed in the impetigo strain Alab49, loss of FbaA resulted in a slight but significant decrease in GAS fitness in a humanized mouse model of impetigo; the ΔfbaA mutant also exhibited decreased survival in whole human blood due to phagocytosis. In assays with highly sensitive outcome measures, Alab49ΔfbaA was compared to other isogenic mutants lacking virulence genes known to be disproportionately associated with classical skin strains. FbaA and PAM (i.e., the M53 protein) had additive effects in promoting GAS survival in whole blood. The pilus adhesin tip protein Cpa promoted Alab49 survival in whole blood and appears to fully account for the antiphagocytic effect attributable to pili. The finding that numerous skin strain-associated virulence factors make slight but significant contributions to virulence underscores the incremental contributions to fitness of individual surface protein genes and the multifactorial nature of GAS-host interactions. Copyright © 2017 American Society for Microbiology.

  5. Genetic Determinants of Japanese Encephalitis Virus Vaccine Strain SA14-14-2 That Govern Attenuation of Virulence in Mice.

    Science.gov (United States)

    Gromowski, Gregory D; Firestone, Cai-Yen; Whitehead, Stephen S

    2015-06-01

    The safety and efficacy of the live-attenuated Japanese encephalitis virus (JEV) SA14-14-2 vaccine are attributed to mutations that accumulated in the viral genome during its derivation. However, little is known about the contribution that is made by most of these mutations to virulence attenuation and vaccine immunogenicity. Here, we generated recombinant JEV (rJEV) strains containing JEV SA14-14-2 vaccine-specific mutations that are located in the untranslated regions (UTRs) and seven protein genes or are introduced from PCR-amplified regions of the JEV SA14-14-2 genome. The resulting mutant viruses were evaluated in tissue culture and in mice. The authentic JEV SA14-14-2 (E) protein, with amino acid substitutions L107F, E138K, I176V, T177A, E244G, Q264H, K279M, A315V, S366A, and K439R relative to the wild-type rJEV clone, was essential and sufficient for complete attenuation of neurovirulence. Individually, the nucleotide substitution T39A in the 5' UTR (5'-UTR-T39A), the capsid (C) protein amino acid substitution L66S (C-L66S), and the complete NS1/2A genome region containing 10 mutations each significantly reduced virus neuroinvasion but not neurovirulence. The levels of peripheral virulence attenuation imposed by the 5'-UTR-T39A and C-L66S mutations, individually, were somewhat mitigated in combination with other vaccine strain-specific mutations, which might be compensatory, and together did not affect immunogenicity. However, a marked reduction in immunogenicity was observed with the addition of the NS1/2A and NS5 vaccine virus genome regions. These results suggest that a second-generation recombinant vaccine can be rationally engineered to maximize levels of immunogenicity without compromising safety. The live-attenuated JEV SA14-14-2 vaccine has been vital for controlling the incidence of disease caused by JEV, particularly in rural areas of Asia where it is endemic. The vaccine was developed >25 years ago by passaging wild-type JEV strain SA14 in tissue

  6. Comparative analysis of virulence traits between a Legionella feeleii strain implicated in Pontiac fever and a strain that caused Legionnaires' disease.

    Science.gov (United States)

    Wang, Changle; Saito, Mitsumasa; Tanaka, Tamami; Amako, Kazunobu; Yoshida, Shin-ichi

    2015-12-01

    Legionella strains of the same species and serogroup are known to cause Legionnaires' disease (a potentially fatal atypical pneumonia) or Pontiac fever (a mild, flu-like disease), but the bacterial factors that define these dramatic differences in pathology have not been elucidated. To gain a better understanding of these factors, we compared the characteristics of Legionella feeleii strains that were isolated from either a sample of freshwater implicated in an outbreak of Pontiac fever (ATCC 35072, serogroup 1, LfPF), or a patient with Legionnaires' disease (ATCC 38549, serogroup 2, LfLD). Growth of LfPF and LfLD in BYE broth was slower than the positive control, Legionella pneumophila strain JR32. However, LfLD grew faster than LfPF at 42 °C. After in vitro infection to J774 murine or U937 human macrophage cell lines and A549 human lung epithelial cell line, LfLD showed a higher cell infection rate, stronger internalization by host cells, and greater cytotoxicity than that of LfPF. Large amounts of IL-6 and IL-8 were secreted by human host cells after infection with LfLD, but not with LfPF. LfLD possessed mono-polar flagellum while LfPF was unflagellated. When LfLD was cultured at 25, 30 and 37 °C, the bacteria had higher motility rate at lower temperatures. Based on our results, this is the first study that showed distinct characteristics between LfPF and LfLD, which may give important leads in elucidating differences in their virulence. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Virulence, immunogenicity and vaccine properties of a novel chimeric pestivirus

    DEFF Research Database (Denmark)

    Rasmussen, Thomas Bruun; Uttenthal, Åse; Reimann, Ilona

    2007-01-01

    A chimeric pestivirus of border disease virus Gifhorn and bovine viral diarrhea virus CP7 (Meyers et al., 1996) was constructed. Virulence, immunogenicity and vaccine properties of the chimeric virus were studied in a vaccination–challenge experiment in pigs. The chimeric virus proved...... to be avirulent and neither chimeric virus nor viral RNA was detected in serum after vaccination. The safety of the vaccine was tested by horizontal transmission to sentinel pigs, which remained uninfected. The vaccine efficacy was examined by challenge infection with classical swine fever virus (CSFV) Eystrup....... In ‘challenge controls’, the viral load of CSFV coincided with the development of pronounced clinical symptoms. In contrast, the vaccinated pigs showed transient and weak clinical signs. Analysis of the viral load in these pigs showed 1000-fold lower viral RNA levels compared to ‘challenge controls...

  8. Antibiotic resistance, virulence factors and biofilm formation ability in Escherichia coli strains isolated from chicken meat and wildlife in the Czech Republic.

    Science.gov (United States)

    Pavlickova, Silvie; Klancnik, Anja; Dolezalova, Magda; Mozina, Sonja Smole; Holko, Ivan

    2017-08-03

    Attachment of pathogenic bacteria to food contact surfaces and the subsequent biofilm formation represent a serious threat for the food industry, since these bacteria are more resistant to antimicrobials or possess more virulence factors. The main aim of this study was to investigate the correlation between antibiotic resistance against 13 antibiotics, distribution of 10 virulence factors and biofilm formation in 105 Escherichia coli strains according to their origin. The high prevalence of antibiotic resistance that we have found in wildlife isolates could be acquired by horizontal transfer of resistance genes from human or domestic or farm animals. Consequently, these commensal bacteria might serve as indicator of antimicrobial usage for human and veterinary purposes in the Czech Republic. Further, 46 out of 66 resistant isolates (70%) were able to form biofilm and we found out statistically significant correlation between prevalence of antibiotic resistance and biofilm formation ability. The highest prevalence of antibiotic resistance was observed in weak biofilm producers. Biofilm formation was not statistically associated with any virulence determinant. However, we confirmed the correlation between prevalence of virulence factors and host origin. Chicken isolates possessed more virulence factors (66%), than isolates from wildlife (37%). We can conclude that the potential spread of antibiotic resistance pattern via the food chain is of high concern for public health. Even more, alarming is that E. coli isolates remain pathogenic potential with ability to form biofilm and these bacteria may persist during food processing and consequently lead to greater risks of food contamination.

  9. Proteomic profiling of Pseudomonas aeruginosa AES-1R, PAO1 and PA14 reveals potential virulence determinants associated with a transmissible cystic fibrosis-associated strain.

    Science.gov (United States)

    Hare, Nathan J; Solis, Nestor; Harmer, Christopher; Marzook, N Bishara; Rose, Barbara; Harbour, Colin; Crossett, Ben; Manos, Jim; Cordwell, Stuart J

    2012-01-22

    Pseudomonas aeruginosa is an opportunistic pathogen that is the major cause of morbidity and mortality in patients with cystic fibrosis (CF). While most CF patients are thought to acquire P. aeruginosa from the environment, person-person transmissible strains have been identified in CF clinics worldwide. The molecular basis for transmissibility and colonization of the CF lung remains poorly understood. A dual proteomics approach consisting of gel-based and gel-free comparisons were undertaken to analyse protein profiles in a transmissible, early (acute) isolate of the Australian epidemic strain 1 (AES-1R), the virulent burns/wound isolate PA14, and the poorly virulent, laboratory-associated strain PAO1. Over 1700 P. aeruginosa proteins were confidently identified. AES-1R protein profiles revealed elevated abundance of proteins associated with virulence and siderophore biosynthesis and acquisition, antibiotic resistance and lipopolysaccharide and fatty acid biosynthesis. The most abundant protein in AES-1R was confirmed as a previously hypothetical protein with sequence similarity to carbohydrate-binding proteins and database search revealed this gene is only found in the CF-associated strain PA2192. The link with CF infection may suggest that transmissible strains have acquired an ability to rapidly interact with host mucosal glycoproteins. Our data suggest that AES-1R expresses higher levels of proteins, such as those involved in antibiotic resistance, iron acquisition and virulence that may provide a competitive advantage during early infection in the CF lung. Identification of novel proteins associated with transmissibility and acute infection may aid in deciphering new strategies for intervention to limit P. aeruginosa infections in CF patients.

  10. Phylogenetic group distributions, virulence factors and antimicrobial resistance properties of uropathogenic Escherichia coli strains isolated from patients with urinary tract infections in South Korea.

    Science.gov (United States)

    Lee, J H; Subhadra, B; Son, Y-J; Kim, D H; Park, H S; Kim, J M; Koo, S H; Oh, M H; Kim, H-J; Choi, C H

    2016-01-01

    Urinary tract infections (UTIs) are one of the most common diseases by which humans seek medical help and are caused mainly by uropathogenic Escherichia coli (UPEC). Studying the virulence and antibiotic resistance of UPEC with respect to various phylogenetic groups is of utmost importance in developing new therapeutic agents. Thus, in this study, we analysed the virulence factors, antibiotic resistance and phylogenetic groups among various UPEC isolates from children with UTIs. The phylogenetic analysis revealed that majority of the strains responsible for UTIs belonged to the phylogenetic groups B2 and D. Of the 58 E. coli isolates, 79·31% belonged to group B2, 15·51% to group D, 3·44% to group A and 1·72% to B1. Simultaneously, the number of virulence factors and antibiotic resistance exhibited were also significantly high in groups B2 and D compared to other groups. Among the isolates, 44·8% were multidrug resistant and of that 73% belonged to the phylogenetic group B2, indicating the compatibility of antibiotic resistance and certain strains carrying virulence factor genes. The antibiotic resistance profiling of UPEC strains elucidates that the antimicrobial agents such as chloramphenicol, cefoxitin, cefepime, ceftazidime might still be used in the therapy for treating UTIs. As the antibiotic resistance pattern of uropathogenic Escherichia coli varies depending on different geographical regions, the antibiotic resistance pattern from this study will help the physicians to effectively administer antibiotic therapy for urinary tract infections. In addition, the frequency of virulence factors and antibiotic resistance genes among various phylogenic groups could be effectively used to draw new targets for uropathogenic Escherichia coli antibiotic-independent therapies. The study emphasizes need of public awareness on multidrug resistance and for more prudent use of antimicrobials. © 2015 The Society for Applied Microbiology.

  11. Metabolite Transporter PEG344 Is Required for Full Virulence of Hypervirulent Klebsiella pneumoniae Strain hvKP1 after Pulmonary but Not Subcutaneous Challenge.

    Science.gov (United States)

    Bulger, Jeffrey; MacDonald, Ulrike; Olson, Ruth; Beanan, Janet; Russo, Thomas A

    2017-10-01

    Hypervirulent Klebsiella pneumoniae (hvKP) is an emerging pathotype that is capable of causing tissue-invasive and organ- and life-threatening infections in healthy individuals from the community. Knowledge on the virulence factors specific to hvKP is limited. In this report, we describe a new factor (PEG344) that increases the virulence of hvKP strain hvKP1. peg-344 is present on the hvKP1 virulence plasmid, is broadly prevalent among hvKP strains, and has increased RNA abundance when grown in human ascites. An isogenic derivative of hvKP1 (hvKP1Δ peg-344 ) was constructed and compared with its wild-type parent strain in in vitro , ex vivo , and infection model studies. Both survival and competition experiments with outbred CD1 mice demonstrated that PEG344 was required for full virulence after pulmonary challenge but, interestingly, not after subcutaneous challenge. In silico analysis suggested that PEG344 serves as an inner membrane transporter. Compared to hvKP1, a small but significant decrease in the growth/survival of hvKP1Δ peg-344 was observed in human ascites, but resistance to the bactericidal activity of complement was similar. These data suggested that PEG344 may transport an unidentified growth factor present in ascites. The data presented are important since they expand our limited knowledge base on virulence factors unique to hvKP, which is needed to lay the groundwork for translational approaches to prevent or treat these devastating infections. Copyright © 2017 American Society for Microbiology.

  12. [Immunochemical differences in the surface polysaccharides obtained from Entamoeba histolytica strain HM1:IMSS and its virulent (C-A) and non-virulent (L-6) clones].

    Science.gov (United States)

    Isibasi, A; Blanco, F; Arreguín, C; Martínez, G; Pelayo, R; Orozco, E; Kumate, J

    1990-01-01

    There probably exist many different surface molecular polysaccharides with different compositions of their constituent sugars, in the different zymodemes. This fact might have a repercussion upon the resistance to the lysis of the complement. Seeking to prove this hypothesis, the ideal would be to obtain polysaccharide molecules of type LPFG of pathogenic and non-pathogenic zymodemes, demonstrating that there is a difference in the chemical composition of their polysaccharides. If this were true, a serologic classification, of the different zymodemes, would be possible in a fashion similar to gram-negative bacteria. Our results suggest the existence of structural differences between the polysaccharides of a virulent clone (C-A) and a non-virulent one (L-6).

  13. Carriage of extended-spectrum beta-lactamase-plasmids does not reduce fitness but enhances virulence in some strains of pandemic E. coli lineages

    Directory of Open Access Journals (Sweden)

    Katharina eSchaufler

    2016-03-01

    Full Text Available Pathogenic ESBL-producing E. coli lineages occur frequently worldwide, not only in a human health context but in animals and the environment, also in settings with low antimicrobial pressures. This study investigated the fitness costs of ESBL-plasmids and their influence on chromosomally encoded features associated with virulence, such as those involved in the planktonic and sessile behaviors of ST131 and ST648 E. coli. ESBL-plasmid-carrying wild-type E. coli strains, their corresponding ESBL-plasmid-cured variants (PCV, and complementary ESBL-carrying transformants were comparatively analyzed using growth curves, Omnilog® phenotype microarray (PM assays, macrocolony and biofilm formation, swimming motility, and RNA sequence analysis. Growth curves and PM results pointed towards similar growth and metabolic behaviors among the strains. Phenotypic differences in some strains were detected, including enhanced curli fimbriae and/or cellulose production as well as a reduced swimming capacity of some ESBL-carrying strains, as compared to their respective PCVs. RNA sequencing mostly confirmed the phenotypic results, suggesting that the chromosomally encoded csgD pathway is a key factor involved. These results contradict the hypothesis that ESBL-plasmid-carriage leads to a fitness loss in ESBL-carrying strains. Instead, the results indicate an influence of some ESBL-plasmids on chromosomally encoded features associated with virulence in some E. coli strains. In conclusion, apart from antibiotic resistance selective advantages, ESBL-plasmid-carriage may also lead to enhanced virulence or adaption to specific habitats in some strains of pandemic ESBL-producing E. coli lineages.

  14. Virulence and pathogenesis of the MSW and MSD strains of Californian myxoma virus in European rabbits with genetic resistance to myxomatosis compared to rabbits with no genetic resistance.

    Science.gov (United States)

    Silvers, L; Inglis, B; Labudovic, A; Janssens, P A; van Leeuwen, B H; Kerr, P J

    2006-04-25

    The pathogenesis of two Californian strains of myxoma virus (MSW and MSD) was examined in European rabbits (Oryctolagus cuniculus) that were either susceptible to myxomatosis (laboratory rabbits) or had undergone natural selection for genetic resistance to myxomatosis (Australian wild rabbits). MSW was highly lethal for both types of rabbits with average survival times of 7.3 and 9.4 days, respectively, and 100% mortality. Classical clinical signs of myxomatosis were not present except in one rabbit that survived for 13 days following infection. Previously described clinical signs of trembling and shaking were observed in laboratory but not wild rabbits. Despite the high resistance of wild rabbits to myxomatosis caused by South American strains of myxoma virus, the MSW strain was of such high virulence that it was able to overcome resistance. The acute nature of the infection, relatively low viral titers in the tissues and destruction of lymphoid tissues, suggested that death was probably due to an acute and overwhelming immunopathological response to the virus. No virus was found in the brain. The MSD strain was attenuated compared to previously published descriptions and therefore was only characterized in laboratory rabbits. It is concluded that Californian MSW strain of myxoma virus is at the extreme end of a continuum of myxoma virus virulence but that the basic pathophysiology of the disease induced is not broadly different to other strains of myxoma virus.

  15. The roles of the shikimate pathway genes, aroA and aroB, in virulence, growth and UV tolerance of Burkholderia glumae strain 411gr-6.

    Science.gov (United States)

    Karki, Hari Sharan; Ham, Jong Hyun

    2014-12-01

    Burkholderia glumae is the major causal agent of bacterial panicle blight of rice, which is a growing disease problem for rice growers worldwide. In our previous study, some B. glumae strains showed pigmentation phenotypes producing at least two (yellow-green and purple) pigment compounds in casein-peptone-glucose agar medium. The B. glumae strains LSUPB114 and LSUPB116 are pigment-deficient mutant derivatives of the virulent and pigment-proficient strain 411gr-6, having mini-Tn5gus insertions in aroA encoding 3-phosphoshikimate 1-carboxyvinyltransferase and aroB encoding 3-dehydroquinate synthase, respectively. Both enzymes are known to be involved in the shikimate pathway, which leads to the synthesis of aromatic amino acids. Here, we demonstrate that aroA and aroB are required for normal virulence in rice and onion, growth in M9 minimal medium and tolerance to UV light, but are dispensable for the production of the phytotoxin toxoflavin. These results suggest that the shikimate pathway is involved in bacterial pathogenesis by B. glumae without a significant role in the production of toxoflavin, a major virulence factor of this pathogen. © 2014 BSPP AND JOHN WILEY & SONS LTD.

  16. CovRS-Regulated Transcriptome Analysis of a Hypervirulent M23 Strain of Group A Streptococcus pyogenes Provides New Insights into Virulence Determinants.

    Science.gov (United States)

    Bao, Yun-Juan; Liang, Zhong; Mayfield, Jeffrey A; Lee, Shaun W; Ploplis, Victoria A; Castellino, Francis J

    2015-10-01

    The two-component control of virulence (Cov) regulator (R)-sensor (S) (CovRS) regulates the virulence of Streptococcus pyogenes (group A Streptococcus [GAS]). Inactivation of CovS during infection switches the pathogenicity of GAS to a more invasive form by regulating transcription of diverse virulence genes via CovR. However, the manner in which CovRS controls virulence through expression of extended gene families has not been fully determined. In the current study, the CovS-regulated gene expression profiles of a hypervirulent emm23 GAS strain (M23ND/CovS negative [M23ND/CovS(-)]) and a noninvasive isogenic strain (M23ND/CovS(+)), under different growth conditions, were investigated. RNA sequencing identified altered expression of ∼ 349 genes (18% of the chromosome). The data demonstrated that M23ND/CovS(-) achieved hypervirulence by allowing enhanced expression of genes responsible for antiphagocytosis (e.g., hasABC), by abrogating expression of toxin genes (e.g., speB), and by compromising gene products with dispensable functions (e.g., sfb1). Among these genes, several (e.g., parE and parC) were not previously reported to be regulated by CovRS. Furthermore, the study revealed that CovS also modulated the expression of a broad spectrum of metabolic genes that maximized nutrient utilization and energy metabolism during growth and dissemination, where the bacteria encounter large variations in available nutrients, thus restructuring metabolism of GAS for adaption to diverse growth environments. From constructing a genome-scale metabolic model, we identified 16 nonredundant metabolic gene modules that constitute unique nutrient sources. These genes were proposed to be essential for pathogen growth and are likely associated with GAS virulence. The genome-wide prediction of genes associated with virulence identifies new candidate genes that potentially contribute to GAS virulence. The CovRS system modulates transcription of ∼ 18% of the genes in the

  17. Serum resistance of Pasteurella multocida in avian and porcine sera, and comparative virulence investigations of selected serum-sensitive and resistant strains in chickens.

    Science.gov (United States)

    Muhairwa, Amandus P; Christensen, Jens P; Bisgaard, Magne

    2002-04-01

    Growth in serum of Pasteurella multocida and related species in chicken, turkey, duck and pig sera were compared, and selected serum-resistant and serum-sensitive strains were inoculated into 18-week-old layers. Eighty-seven field strains of Pasteurella spp. and nine reference strains representing different clones defined by restriction endonuclease analysis (REA) profiles were used in the study. Serum activity was measured by changes in the optical density (OD) of the serum after inoculation and incubation at 41 degrees C for chicken, turkey and duck serum and 39 degrees C for pig serum. Serum activity was measured by comparison with previously determined serum-resistant (P-1059) and serum-sensitive (CU vaccine) strains, and classified into highly serum-resistant, moderately serum-resistant and serum-sensitive. Strains of the same REA type were found to have identical growth curves and the same maximum OD values when tested in serum from the same host species. Turkey serum was shown to be less inhibitory to a wide range of P. multocida strains than chicken, duck and pig sera. Serum-resistant strains were demonstrated among avian as well as mammalian strains. Among the avian strains, the proportion of serum-resistant strains was higher in outbreak strains than in strains from apparently healthy carriers. Removal of the capsule from selected strains by hyaluronidase treatment failed to change the serum activity. The most severe lesions in experimentally infected chickens were produced by a serum-resistant strain; however, lesions were also found in chickens infected by serum-sensitive strains, indicating the involvement of multiple factors in the virulence of P. multocida. Further investigations on serum resistance are indicated in order to relate other host and bacterial factors responsible for the development of fowl cholera.

  18. Challenge of Pigs with Classical Swine Fever Viruses after C-Strain Vaccination Reveals Remarkably Rapid Protection and Insights into Early Immunity

    Science.gov (United States)

    Haines, Felicity J.; Johns, Helen L.; Sosan, Olubukola A.; Salguero, Francisco J.; Clifford, Derek J.; Steinbach, Falko; Drew, Trevor W.; Crooke, Helen R.

    2012-01-01

    Pre-emptive culling is becoming increasingly questioned as a means of controlling animal diseases, including classical swine fever (CSF). This has prompted discussions on the use of emergency vaccination to control future CSF outbreaks in domestic pigs. Despite a long history of safe use in endemic areas, there is a paucity of data on aspects important to emergency strategies, such as how rapidly CSFV vaccines would protect against transmission, and if this protection is equivalent for all viral genotypes, including highly divergent genotype 3 strains. To evaluate these questions, pigs were vaccinated with the Riemser® C-strain vaccine at 1, 3 and 5 days prior to challenge with genotype 2.1 and 3.3 challenge strains. The vaccine provided equivalent protection against clinical disease caused by for the two challenge strains and, as expected, protection was complete at 5 days post-vaccination. Substantial protection was achieved after 3 days, which was sufficient to prevent transmission of the 3.3 strain to animals in direct contact. Even by one day post-vaccination approximately half the animals were partially protected, and were able to control the infection, indicating that a reduction of the infectious potential is achieved very rapidly after vaccination. There was a close temporal correlation between T cell IFN-γ responses and protection. Interestingly, compared to responses of animals challenged 5 days after vaccination, challenge of animals 3 or 1 days post-vaccination resulted in impaired vaccine-induced T cell responses. This, together with the failure to detect a T cell IFN-γ response in unprotected and unvaccinated animals, indicates that virulent CSFV can inhibit the potent antiviral host defences primed by C-strain in the early period post vaccination. PMID:22235283

  19. Genetic basis of virulence attenuation revealed by comparative genomic analysis of Mycobacterium tuberculosis strain H37Ra versus H37Rv.

    Directory of Open Access Journals (Sweden)

    Huajun Zheng

    2008-06-01

    Full Text Available Tuberculosis, caused by Mycobacterium tuberculosis, remains a leading infectious disease despite the availability of chemotherapy and BCG vaccine. The commonly used avirulent M. tuberculosis strain H37Ra was derived from virulent strain H37 in 1935 but the basis of virulence attenuation has remained obscure despite numerous studies. We determined the complete genomic sequence of H37Ra ATCC25177 and compared that with its virulent counterpart H37Rv and a clinical isolate CDC1551. The H37Ra genome is highly similar to that of H37Rv with respect to gene content and order but is 8,445 bp larger as a result of 53 insertions and 21 deletions in H37Ra relative to H37Rv. Variations in repetitive sequences such as IS6110 and PE/PPE/PE-PGRS family genes are responsible for most of the gross genetic changes. A total of 198 single nucleotide variations (SNVs that are different between H37Ra and H37Rv were identified, yet 119 of them are identical between H37Ra and CDC1551 and 3 are due to H37Rv strain variation, leaving only 76 H37Ra-specific SNVs that affect only 32 genes. The biological impact of missense mutations in protein coding sequences was analyzed in silico while nucleotide variations in potential promoter regions of several important genes were verified by quantitative RT-PCR. Mutations affecting transcription factors and/or global metabolic regulations related to in vitro survival under aging stress, and mutations affecting cell envelope, primary metabolism, in vivo growth as well as variations in the PE/PPE/PE-PGRS family genes, may underlie the basis of virulence attenuation. These findings have implications not only for improved understanding of pathogenesis of M. tuberculosis but also for development of new vaccines and new therapeutic agents.

  20. AB5075, a Highly Virulent Isolate of Acinetobacter baumannii, as a Model Strain for the Evaluation of Pathogenesis and Antimicrobial Treatments.

    Science.gov (United States)

    Jacobs, Anna C; Thompson, Mitchell G; Black, Chad C; Kessler, Jennifer L; Clark, Lily P; McQueary, Christin N; Gancz, Hanan Y; Corey, Brendan W; Moon, Jay K; Si, Yuanzheng; Owen, Matthew T; Hallock, Justin D; Kwak, Yoon I; Summers, Amy; Li, Charles Z; Rasko, David A; Penwell, William F; Honnold, Cary L; Wise, Matthew C; Waterman, Paige E; Lesho, Emil P; Stewart, Rena L; Actis, Luis A; Palys, Thomas J; Craft, David W; Zurawski, Daniel V

    2014-05-27

    Acinetobacter baumannii is recognized as an emerging bacterial pathogen because of traits such as prolonged survival in a desiccated state, effective nosocomial transmission, and an inherent ability to acquire antibiotic resistance genes. A pressing need in the field of A. baumannii research is a suitable model strain that is representative of current clinical isolates, is highly virulent in established animal models, and can be genetically manipulated. To identify a suitable strain, a genetically diverse set of recent U.S. military clinical isolates was assessed. Pulsed-field gel electrophoresis and multiplex PCR determined the genetic diversity of 33 A. baumannii isolates. Subsequently, five representative isolates were tested in murine pulmonary and Galleria mellonella models of infection. Infections with one strain, AB5075, were considerably more severe in both animal models than those with other isolates, as there was a significant decrease in survival rates. AB5075 also caused osteomyelitis in a rat open fracture model, while another isolate did not. Additionally, a Tn5 transposon library was successfully generated in AB5075, and the insertion of exogenous genes into the AB5075 chromosome via Tn7 was completed, suggesting that this isolate may be genetically amenable for research purposes. Finally, proof-of-concept experiments with the antibiotic rifampin showed that this strain can be used in animal models to assess therapies under numerous parameters, including survival rates and lung bacterial burden. We propose that AB5075 can serve as a model strain for A. baumannii pathogenesis due to its relatively recent isolation, multidrug resistance, reproducible virulence in animal models, and genetic tractability. The incidence of A. baumannii infections has increased over the last decade, and unfortunately, so has antibiotic resistance in this bacterial species. A. baumannii is now responsible for more than 10% of all hospital-acquired infections in the

  1. Comparison between virulence characteristics of dominant and non-dominant Escherichia coli strains of the gut and their interaction with Caco-2 cells.

    Science.gov (United States)

    Owrangi, B; Masters, N; Vollmerhausen, T L; O'Dea, C; Kuballa, A; Katouli, M

    2017-04-01

    Escherichia coli strains are normal inhabitants of the gut and are normally found in the faeces of the host at different population sizes. We characterised faecal E. coli of 45 healthy male (n = 17) and female (n = 28) volunteers by testing 28 isolates from each individual. These isolates were typed and divided into dominant (if constituted >50% of the population tested) and non-dominant types in each individual. Representative strains of each dominant and non-dominant type were tested for their virulence gene profiles, their ability to form biofilm, adhere to, invade and translocate through a gut epithelial cell line (Caco-2 cells). Strains belonging to dominant types adhered significantly more to Caco-2 cells than non-dominant strains (5.7 ± 0.3 versus 4.3.± 0.13 CFU/cell mean ± SEM, P = 0.0003). They also invaded (135 ± 6 versus 63 ± 13 CFU) and translocated through Caco-2 cells (84 ± 5 versus 32 ± 9 CFU) significantly more than non-dominant strains (P < 0.0001 and P = 0.0002, respectively). Moreover, dominant strains showed the ability to form significantly more biofilm than non-dominant strains (1.1 ± 0.01 versus 0.5 ± 0.1 OD600, P < 0.0001). Majority (51%) of the strains belonged to phylogroup D followed by B2 (23%). Furthermore, out of 25 virulence genes tested, kpsMTII, papC and papG allele III were found to be significantly higher among dominant than non-dominant strains. Our results suggest that E. coli strains dominating the gut may have virulence properties that enable them to efficiently interact with the gut epithelium and translocate under predisposing conditions of the host. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Conjugation-mediated horizontal gene transfer of Clostridium perfringens plasmids in the chicken gastrointestinal tract results in the formation of new virulent strains.

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    Lacey, Jake A; Keyburn, Anthony L; Ford, Mark E; Portela, Ricardo W; Johanesen, Priscilla A; Lyras, Dena; Moore, Robert J

    2017-10-13

    Clostridium perfringens is a gastrointestinal pathogen capable of causing disease in a variety of hosts. Necrotic enteritis in chickens is caused by C. perfringens strains that produce the pore-forming toxin NetB, the major virulence factor for this disease. Like many other C. perfringens toxins and antibiotic resistance genes, NetB is encoded on a conjugative plasmid. Conjugative transfer of the netB-containing plasmid pJIR3535 has been demonstrated in vitro with a netB null mutant. This study has investigated the effect of plasmid transfer on disease pathogenesis, with two genetically distinct transconjugants constructed under in vitro conditions, within the intestinal tract of chickens. This study also demonstrates that plasmid transfer can occur naturally in the host gut environment, without the need for antibiotic selective pressure to be applied. The demonstration of plasmid transfer within the chicken host may have implications for disease progression and pathogenesis of C. perfringens-mediated disease. Such horizontal gene transfer events are likely to be common in the clostridia and may be a key factor in strain evolution, both within animals and in the wider environment.ImportanceClostridium perfringens is a major gastrointestinal pathogen of poultry. C. perfringens strains that express the NetB pore-forming toxin, which is encoded on a conjugative plasmid, cause necrotic enteritis. This study demonstrated that the conjugative transfer of the netB containing plasmid to two different non-pathogenic strains converted them into disease causing strains with similar disease-causing capability as the donor strain. Plasmid transfer of netB and antibiotic resistance was also demonstrated to occur within the gastrointestinal tract of chickens, with approximately 14% of isolates recovered comprising of three distinct, in vivo derived, transconjugant types. The demonstration of in vivo plasmid transfer indicates the potential importance of strain plasticity and the

  3. Association of virulence plasmid and antibiotic resistance determinants with chromosomal multilocus genotypes in Mexican Salmonella enterica serovar Typhimurium strains

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    Silva Claudia

    2009-07-01

    Full Text Available Abstract Background Bacterial genomes are mosaic structures composed of genes present in every strain of the same species (core genome, and genes present in some but not all strains of a species (accessory genome. The aim of this study was to compare the genetic diversity of core and accessory genes of a Salmonella enterica subspecies enterica serovar Typhimurium (Typhimurium population isolated from food-animal and human sources in four regions of Mexico. Multilocus sequence typing (MLST and macrorestriction fingerprints by pulsed-field gel electrophoresis (PFGE were used to address the core genetic variation, and genes involved in pathogenesis and antibiotic resistance were selected to evaluate the accessory genome. Results We found a low genetic diversity for both housekeeping and accessory genes. Sequence type 19 (ST19 was supported as the founder genotype of STs 213, 302 and 429. We found a temporal pattern in which the derived ST213 is replacing the founder ST19 in the four geographic regions analyzed and a geographic trend in the number of resistance determinants. The distribution of the accessory genes was not random among chromosomal genotypes. We detected strong associations among the different accessory genes and the multilocus chromosomal genotypes (STs. First, the Salmonella virulence plasmid (pSTV was found mostly in ST19 isolates. Second, the plasmid-borne betalactamase cmy-2 was found only in ST213 isolates. Third, the most abundant integron, IP-1 (dfrA12, orfF and aadA2, was found only in ST213 isolates. Fourth, the Salmonella genomic island (SGI1 was found mainly in a subgroup of ST19 isolates carrying pSTV. The mapping of accessory genes and multilocus genotypes on the dendrogram derived from macrorestiction fingerprints allowed the establishment of genetic subgroups within the population. Conclusion Despite the low levels of genetic diversity of core and accessory genes, the non-random distribution of the accessory genes

  4. A subset of naturally isolated Bacillus strains show extreme virulence to the free-living nematodes Caenorhabditis elegans and Pristionchus pacificus.

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    Rae, Robbie; Iatsenko, Igor; Witte, Hahn; Sommer, Ralf J

    2010-11-01

    The main food source of free-living nematodes in the soil environment is bacteria, which can affect nematode development, fecundity and survival. In order to occupy a reliable source of bacterial food, some nematodes have formed specific relationships with an array of invertebrate hosts (where bacteria proliferate once the hosts dies), thus forming a tritrophic system of nematode, bacteria and insect or other invertebrates. We isolated 768 Bacillus strains from soil (from Germany and the UK), horse dung and dung beetles and fed them to the genetically tractable free-living nematodes Caenorhabditis elegans and Pristionchus pacificus to isolate nematocidal strains. While C. elegans is a bacteriovorous soil nematode, P. pacificus is an omnivorous worm that is often found in association with scarab beetles. We found 20 Bacillus strains (consisting of B. cereus, B. weihenstephanensis, B. mycoides and Bacillus sp.) that were pathogenic to C. elegans and P. pacificus causing 70% to 100% mortality over 5 days and significantly affect development and brood size. The most pathogenic strains are three B. cereus-like strains isolated from dung beetles, which exhibit extreme virulence to C. elegans in less than 24 h, but P. pacificus remains resistant. C. elegans Bre mutants were also highly susceptible to the B. cereus-like strains indicating that their toxins use a different virulence mechanism than B. thuringiensis Cry 5B toxin. Also, mutations in the daf-2/daf-16 insulin signaling pathway do not rescue survival. We profiled the toxin genes (bcet, nhe complex, hbl complex, pcpl, sph, cytK, piplc, hly2, hly3, entFM and entS) of these three B. cereus-like strains and showed presence of most toxin genes but absence of the hbl complex. Taken together, this study shows that the majority of naturally isolated Bacillus from soil, horse dung and Geotrupes beetles are benign to both C. elegans and P. pacificus. Among 20 pathogenic strains with distinct virulence patterns against the

  5. Virulence-associated factors in Vibrio cholerae non-O1/non-O139 and V. mimicus strains isolated in ornamental fish species.

    Science.gov (United States)

    Zago, V; Zambon, M; Civettini, M; Zaltum, O; Manfrin, A

    2017-12-01

    During recent decades, ornamental fish have proven to be one of the fastest growing categories of pets in Europe. In this framework, we evaluated both the potential pathogenic and zoonotic risks caused by 53 Vibrio cholerae non-O1/non-O139 and a Vibrio mimicus strain isolated from ornamental fish species mostly originating from South-East Asia countries between 2000 and 2015 in Italy. All the strains were firstly identified at species level by biochemical, phylogenetic and mass spectrometry (matrix-assisted laser desorption ionization time of flight) methods, and then studied to reveal the presence of the main virulence and colonization-associated factors, as ctxA, ace, zot, stn/sto, toxR, rtxA, hlyA and tcpA by multiplex and single endpoint PCR assays. Findings showed that 21 of 54 strains harboured at least one virulence factor with a predominance for the toxR+ , rtxA+ and hlyAET+ genotype. Interestingly, the V. mimicus strain harboured the colonization factor and the CTX prophage receptor, tcpA, indicating the ability to capture and integrate it in its genome increasing its pathogenicity. Although these enterotoxins can sporadically cause gastroenteritis, the results highlight their probable involvement in causing severe implications for public health, suggesting the need for an European microbiological monitoring. © 2017 John Wiley & Sons Ltd.

  6. Comparative virulence of in vitro-cultured primate- and pig-associated Helicobacter suis strains in a BALB/c mouse and a Mongolian gerbil model.

    Science.gov (United States)

    Bosschem, Iris; Flahou, Bram; Bakker, Jaco; Heuvelman, Edwin; Langermans, Jan A M; De Bruyne, Ellen; Joosten, Myrthe; Smet, Annemieke; Ducatelle, Richard; Haesebrouck, Freddy

    2017-04-01

    Helicobacter suis (H. suis) is the most prevalent gastric non-H. pylori Helicobacter species in humans. This bacterium mainly colonizes the stomach of pigs, but it has also been detected in the stomach of nonhuman primates. The aim of this study was to obtain better insights into potential differences between pig- and primate-associated H. suis strains in virulence and pathogenesis. In vitro-isolated H. suis strains obtained from pigs, cynomolgus monkeys (Macaca fascicularis), and rhesus monkeys (Macaca mulatta) were used for intragastric inoculation of BALB/c mice and Mongolian gerbils. Nine weeks and six months later, samples of the stomach of inoculated and control animals were taken for PCR analysis and histopathological examination. The cynomolgus monkey-associated H. suis strain only colonized the stomach of mice, but not of Mongolian gerbils. All other H. suis strains colonized the stomach in both rodent models. In all colonized animals, severe gastric inflammation was induced. Gastric lymphoid follicles and destruction of the antral epithelium were observed in infected gerbils, but not in mice. Infection with both pig- and primate-associated H. suis strains evoked a similar marked Th17 response in mice and gerbils, accompanied by increased CXCL-13 expression levels. Apart from the cynomolgus monkey-associated strain which was unable of colonizing the stomach of Mongolian gerbils, no substantial differences in virulence were found in rodent models between in vitro-cultured pig-associated, cynomolgus monkey-associated and rhesus monkey-associated H. suis strains. The experimental host determines the outcome of the immune response against H. suis infection, rather than the original host. © 2016 John Wiley & Sons Ltd.

  7. Differential gene expression in chicken primary B cells infected ex vivo with attenuated and very virulent strains of infectious bursal disease virus (IBDV).

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    Dulwich, Katherine L; Giotis, Efstathios S; Gray, Alice; Nair, Venugopal; Skinner, Michael A; Broadbent, Andrew J

    2017-11-20

    Infectious bursal disease virus (IBDV) belongs to the family Birnaviridae and is economically important to the poultry industry worldwide. IBDV infects B cells in the bursa of Fabricius (BF), causing immunosuppression and morbidity in young chickens. In addition to strains that cause classical Gumboro disease, the so-called 'very virulent' (vv) strain, also in circulation, causes more severe disease and increased mortality. IBDV has traditionally been controlled through the use of live attenuated vaccines, with attenuation resulting from serial passage in non-lymphoid cells. However, the factors that contribute to the vv or attenuated phenotypes are poorly understood. In order to address this, we aimed to investigate host cell-IBDV interactions using a recently described chicken primary B-cell model, where chicken B cells are harvested from the BF and cultured ex vivo in the presence of chicken CD40L. We demonstrated that these cells could support the replication of IBDV when infected ex vivo in the laboratory. Furthermore, we evaluated the gene expression profiles of B cells infected with an attenuated strain (D78) and a very virulent strain (UK661) by microarray. We found that key genes involved in B-cell activation and signalling (TNFSF13B, CD72 and GRAP) were down-regulated following infection relative to mock, which we speculate could contribute to IBDV-mediated immunosuppression. Moreover, cells responded to infection by expressing antiviral type I IFNs and IFN-stimulated genes, but the induction was far less pronounced upon infection with UK661, which we speculate could contribute to its virulence.

  8. Frequency of vacA, cagA and babA2 virulence markers in Helicobacter pylori strains isolated from Mexican patients with chronic gastritis

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    Negrete Erasmo

    2009-04-01

    Full Text Available Abstract Background Helicobacter pylori has been strongly associated with chronic gastritis, peptic and duodenal ulcers, and it is a risk factor for gastric cancer. Three major virulence factors of H. pylori have been described: the vacuolating toxin (VacA, the cytotoxin-associated gene product (CagA and the adhesion protein BabA2. Since considerable geographic diversity in the prevalence of H. pylori virulence factors has been reported, the aim of this work was to establish the H. pylori and vacA, cagA and babA2 gene status in 238 adult patients, from a marginal urban area of Mexico, with chronic gastritis. Methods H. pylori was identified in cultures of gastric biopsies by nested PCR. vacA and cagA genes were detected by multiplex PCR, whereas babA2 gene was identified by conventional PCR. Results H. pylori-positive biopsies were 143 (60.1%. All H. pylori strains were vacA+; 39.2% were cagA+; 13.3% were cagA+ babA2+ and 8.4% were babA2+. Mexican strains examined possessed the vacA s1, m1 (43.4%, s1, m2 (24.5%, s2, m1 (20.3% and s2, m2 (11.9% genotypes. Conclusion These results show that the Mexican patients suffering chronic gastritis we have studied had a high incidence of infection by H. pylori. Forty four percent (63/143 of the H. pylori strains analyzed in this work may be considered as highly virulent since they possessed two or three of the virulence markers analyzed: vacA s1 cagA babA2 (9.8%, 14/143, vacA s1 babA2 (4.9%, 7/143, and vacA s1 cagA (29.4%, 42/143. However, a statistically significant correlation was not observed between vacAs1, cagA and babA2 virulence markers (χ2 test; P > 0.05.

  9. Genotypic characterization of virulence factors in Escherichia coli strains from patients with cystitis Caracterização genotípica dos fatores de virulência em amostras de Escherichia coli isoladas de pacientes com cistite

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    Monique Ribeiro Tiba

    2008-10-01

    Full Text Available Adhesins (P-fimbriae, S-fimbriae, type 1 fimbriae and afimbrial adhesin, toxins (α-hemolysin and cytotoxic necrotizing factor type 1, iron acquisition systems (aerobactin and host defense avoidance mechanisms (capsule or lipopolysaccharide have been shown to be prevalent in Escherichia coli strains associated with urinary tract infections. In this work, 162 Uropathogenic Escherichia coli (UPEC strains from patients with cystitis were genotypically characterized by polymerase chain reaction (PCR assay. We developed three multiplex PCR assays for virulence-related genes papC, papE/F, papG alleles, fimH, sfa/foc, afaE, hly, cnf-1, usp, cdtB, iucD, and kpsMTII, all of them previously identified in UPEC strains. The PCR assay results identified 158 fimH (97.5%, 86 kpsMTII (53.1%, 53 papC/papEF/papG (32.7%, 45 sfa (27.8%, 42 iucD (25.9%, 41 hly (25.3%, 36 usp (22.2%, 30 cnf-1(18.5% and 10 afa (6.2% strains. No strain was positive for cdtB. In this work, we also demonstrated that adhesins may be multiple within a single strain and that several virulence genes can occur combined in association.Adesinas (Fímbria P, fímbria S, fímbria do tipo 1 e a adesina afimbrial, toxinas (α-hemolisina e o fator necrosante citotóxico do tipo 1, sistemas de captação de ferro (aerobactina, e mecanismos de defesa do hospedeiro (cápsula ou lipopolissacarídeo são prevalentes em amostras de Escherichia coli associadas a infecções do trato urinário. O objetivo deste trabalho foi caracterizar genotipicamente 162 amostras de Escherichia coli uropatogênica (UPEC de pacientes com cistite através do ensaio da reação em cadeia da polimerase. Foram realizados três ensaios de PCR multiplex para os seguintes fatores de virulência: papC, papE/F, alelos de papG, fimH, sfa/foc, afaE, hly, cnf-1, usp, cdtB, iucD, e kpsMTII. Os resultados da PCR identificaram, 158 amostras fimH (97,5%, 86 amostras kpsMTII (53,1%, 53 amostras papC/papEF/papG (32,7%, 45 amostras sfa (27

  10. Surveillance of Virulence Markers and Antibiotic Resistance of Shiga toxin Producing E.coli O157:H7 Strains from Meats Purchase in Shiraz

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    Mohammad Kargar

    2011-09-01

    Full Text Available Background: Shiga toxin Producing Escherichia coli O157:H7 is a common pathogen in cattle, which occasional causes some human disease. This bacterium can potentially contaminate meat and clinical cases of E.coli O157:H7 infections are often associated with consumption of undercooked ground beef. Methods: In this cross-sectional study 122 samples of ground meat were collected and after enrichment in specific culture media and evaluation sorbitol fermentation and their β-glucoronidase activity, the isolation of E.coli O157:H7 strains have been confirmed with specific antisera. Then virulence genes verotoxin, intimin and hemolysin with multiplex PCR and antibiotic resistance strains with disk diffusion method have been tested. Results: Out of specimens that have been supplied, 119 sorbitol negative colonies isolated which 3 strains O157:H7 (2.45% with specific antisera confirmed. Out of considered virulence genes, in two cases of these samples (1.64% the stx1 and eaeA genes were seen and also 2 isolated bacteria had resistance to erythromycin, tetracycline, ampicillin, penicillin, clindamicin, cefixime, novobiocin, and gentamicin antibiotics. Conclusion: As this organism lives in intestines of healthy cattle, preventive measures on cattle farms and during meat processing are necessary.

  11. Modulation of behaviour and virulence of a high alginate expressing Pseudomonas aeruginosa strain from cystic fibrosis by oral commensal bacterium Streptococcus anginosus.

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    Richard D Waite

    Full Text Available Cystic fibrosis (CF airways harbour complex and dynamic polymicrobial communities that include many oral bacteria. Despite increased knowledge of CF airway microbiomes the interaction between established CF pathogens and other resident microbes and resulting impact on disease progression is poorly understood. Previous studies have demonstrated that oral commensal streptococci of the Anginosus group (AGS can establish chronic pulmonary infections and become numerically dominant in CF sputa indicating that they play an important role in CF microbiome dynamics. In this study a strain of Pseudomonas aeruginosa (DWW2 of the mucoid alginate overproducing phenotype associated with chronic CF airway infection and a strain of the oral commensal AGS species Streptococcus anginosus (3a from CF sputum were investigated for their ability to co-exist and their responses to biofilm co-culture. Bacteria in biofilms were quantified, pyocyanin expression by DWW2 was measured and the effect of AGS strain 3a on reversion of DWW2 to a non-mucoidal phenotype investigated. The virulence of DWW2, 3a and colony variant phenotypes of DWW2 in mono- and co-culture were compared in a Galleria mellonella infection model. Co-culture biofilms were formed in normoxic, hypercapnic (10% CO2 and anoxic atmospheres with the streptococcus increasing in number in co-culture, indicating that these bacteria would be able to co-exist and thrive within the heterogeneous microenvironments of the CF airway. The streptococcus caused increased pyocyanin expression by DWW2 and colony variants by stimulating reversion of the mucoid phenotype to the high pyocyanin expressing non-mucoid phenotype. The latter was highly virulent in the infection model with greater virulence when in co-culture with the streptococcus. The results of this study demonstrate that the oral commensal S. anginosus benefits from interaction with P. aeruginosa of the CF associated mucoid phenotype and modulates the

  12. Virulence genes and antimicrobial susceptibility of lactose-negative and lactose-positive strains of Escherichia coli isolated from pregnant women and neonates.

    Science.gov (United States)

    Kaczmarek, Agnieszka; Skowron, Krzysztof; Budzyńska, Anna; Grudlewska, Katarzyna; Gospodarek-Komkowska, Eugenia

    2017-09-01

    Escherichia coli can cause serious infections in the neonates and pregnant women. Although E. coli is widely studied, E. coli lactose-negative (lac-) strains have been rarely described before. So, the aim of this study was to compare lac- and lactose-positive (lac+) E. coli strains in respect of antimicrobial susceptibility and the frequency of virulence genes (VGs). The study included 58 lac+ and 58 lac- E. coli strains isolated from pregnant women and neonates. Culture and the results of biochemical reactions were conducted for lac- and lac+ E. coli identification and differentiation. Disc diffusion test was performed to study the antimicrobial susceptibility of the isolates, and PCR was used to detect VGs. Resistance to at least one of the tested antibiotics was found among 14 (25.9%) E. coli lac+ and in 26 (44.9%) E. coli lac- strains. Both lac+ and lac- E. coli strains were mostly resistant to ampicillin (22.4 and 39.7%) and ticarcillin (20.7 and 39.7%). None of the tested strains produced extended-spectrum β-lactamases (ESBLs). Genes fimH, fimA, iutA, sfa/foc, neuC, ibeA, and hlyF were detected, respectively, in 96.6, 82.8, 32.8, 24.1, 22.4, 12.1, and 6.9% of lac+ E. coli strains and in 94.8, 86.2, 48.3, 19.0, 8.6, 8.6, and 1.7% of lac- strains. The antimicrobial susceptibility and the pathogenic potential of both tested groups of E. coli strains are similar. Therefore, omitting E. coli lac- strains as a potential etiological agent of infections may pose a threat to the health and life of both mothers and neonates.

  13. Differences in virulence of Naegleria fowleri.

    Science.gov (United States)

    De Jonckheere, J

    1979-10-01

    All pathogenic Naegleria fowleri isolated from the environment were highly virulent to mice when instilled intranasally. Axenic cultivation gradually decreased virulence of highly virulent strains. This decrease was most pronounced in environmental isolates and of minor importance in N. fowleri isolated from human cerebrospinal fluid. The low virulent strains obtained by continuous axenic cultivation appeared after clonation to consist of individuals with different virulence. Virulence could be enhanced in low virulent strains by brain passage and passages in Vero cell cultures, but could not be induced by these methods in nonvirulent strains isolated from the environment. Different mice strains showed different sensitivities to infection with pathogenic Naegleria. In addition, older mice were less sensitive than younger animals to low virulent strains.

  14. Complete genome sequence of hypervirulent and outbreak-associated Acinetobacter baumannii strain LAC-4: epidemiology, resistance genetic determinants and potential virulence factors

    Science.gov (United States)

    Ou, Hong-Yu; Kuang, Shan N.; He, Xinyi; Molgora, Brenda M.; Ewing, Peter J.; Deng, Zixin; Osby, Melanie; Chen, Wangxue; Xu, H. Howard

    2015-01-01

    Acinetobacter baumannii is an important human pathogen due to its multi-drug resistance. In this study, the genome of an ST10 outbreak A. baumannii isolate LAC-4 was completely sequenced to better understand its epidemiology, antibiotic resistance genetic determinants and potential virulence factors. Compared with 20 other complete genomes of A. baumannii, LAC-4 genome harbors at least 12 copies of five distinct insertion sequences. It contains 12 and 14 copies of two novel IS elements, ISAba25 and ISAba26, respectively. Additionally, three novel composite transposons were identified: Tn6250, Tn6251 and Tn6252, two of which contain resistance genes. The antibiotic resistance genetic determinants on the LAC-4 genome correlate well with observed antimicrobial susceptibility patterns. Moreover, twelve genomic islands (GI) were identified in LAC-4 genome. Among them, the 33.4-kb GI12 contains a large number of genes which constitute the K (capsule) locus. LAC-4 harbors several unique putative virulence factor loci. Furthermore, LAC-4 and all 19 other outbreak isolates were found to harbor a heme oxygenase gene (hemO)-containing gene cluster. The sequencing of the first complete genome of an ST10 A. baumannii clinical strain should accelerate our understanding of the epidemiology, mechanisms of resistance and virulence of A. baumannii. PMID:25728466

  15. Phytohormone Involvement in the Ustilago maydis- Zea mays Pathosystem: Relationships between Abscisic Acid and Cytokinin Levels and Strain Virulence in Infected Cob Tissue.

    Science.gov (United States)

    Morrison, Erin N; Emery, R J Neil; Saville, Barry J

    2015-01-01

    Ustilago maydis is the causative agent of common smut of corn. Early studies noted its ability to synthesize phytohormones and, more recently these growth promoting substances were confirmed as cytokinins (CKs). Cytokinins comprise a group of phytohormones commonly associated with actively dividing tissues. Lab analyses identified variation in virulence between U. maydis dikaryon and solopathogen infections of corn cob tissue. Samples from infected cob tissue were taken at sequential time points post infection and biochemical profiling was performed using high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI MS/MS). This hormone profiling revealed that there were altered levels of ABA and major CKs, with a marked reduction in CK glucosides, increases in methylthiol CKs and a particularly dramatic increase in cisZ CK forms, in U. maydis infected tissue. These changes were more pronounced in the more virulent dikaryon relative to the solopathogenic strain suggesting a role for cytokinins in moderating virulence during biotrophic infection. These findings highlight the fact that U. maydis does not simply mimic a fertilized seed but instead reprograms the host tissue. Results underscore the suitability of the Ustilago maydis- Zea mays model as a basis for investigating the control of phytohormone dynamics during biotrophic infection of plants.

  16. Phytohormone Involvement in the Ustilago maydis– Zea mays Pathosystem: Relationships between Abscisic Acid and Cytokinin Levels and Strain Virulence in Infected Cob Tissue

    Science.gov (United States)

    Morrison, Erin N.; Emery, R. J. Neil; Saville, Barry J.

    2015-01-01

    Ustilago maydis is the causative agent of common smut of corn. Early studies noted its ability to synthesize phytohormones and, more recently these growth promoting substances were confirmed as cytokinins (CKs). Cytokinins comprise a group of phytohormones commonly associated with actively dividing tissues. Lab analyses identified variation in virulence between U. maydis dikaryon and solopathogen infections of corn cob tissue. Samples from infected cob tissue were taken at sequential time points post infection and biochemical profiling was performed using high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI MS/MS). This hormone profiling revealed that there were altered levels of ABA and major CKs, with a marked reduction in CK glucosides, increases in methylthiol CKs and a particularly dramatic increase in cisZ CK forms, in U. maydis infected tissue. These changes were more pronounced in the more virulent dikaryon relative to the solopathogenic strain suggesting a role for cytokinins in moderating virulence during biotrophic infection. These findings highlight the fact that U. maydis does not simply mimic a fertilized seed but instead reprograms the host tissue. Results underscore the suitability of the Ustilago maydis– Zea mays model as a basis for investigating the control of phytohormone dynamics during biotrophic infection of plants. PMID:26107181

  17. Phytohormone Involvement in the Ustilago maydis- Zea mays Pathosystem: Relationships between Abscisic Acid and Cytokinin Levels and Strain Virulence in Infected Cob Tissue.

    Directory of Open Access Journals (Sweden)

    Erin N Morrison

    Full Text Available Ustilago maydis is the causative agent of common smut of corn. Early studies noted its ability to synthesize phytohormones and, more recently these growth promoting substances were confirmed as cytokinins (CKs. Cytokinins comprise a group of phytohormones commonly associated with actively dividing tissues. Lab analyses identified variation in virulence between U. maydis dikaryon and solopathogen infections of corn cob tissue. Samples from infected cob tissue were taken at sequential time points post infection and biochemical profiling was performed using high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI MS/MS. This hormone profiling revealed that there were altered levels of ABA and major CKs, with a marked reduction in CK glucosides, increases in methylthiol CKs and a particularly dramatic increase in cisZ CK forms, in U. maydis infected tissue. These changes were more pronounced in the more virulent dikaryon relative to the solopathogenic strain suggesting a role for cytokinins in moderating virulence during biotrophic infection. These findings highlight the fact that U. maydis does not simply mimic a fertilized seed but instead reprograms the host tissue. Results underscore the suitability of the Ustilago maydis- Zea mays model as a basis for investigating the control of phytohormone dynamics during biotrophic infection of plants.

  18. Validation of a Novel Immunoline Assay for Patient Stratification according to Virulence of the Infecting Helicobacter pylori Strain and Eradication Status

    Directory of Open Access Journals (Sweden)

    Luca Formichella

    2017-01-01

    Full Text Available Helicobacter pylori infection shows a worldwide prevalence of around 50%. However, only a minority of infected individuals develop clinical symptoms or diseases. The presence of H. pylori virulence factors, such as CagA and VacA, has been associated with disease development, but assessment of virulence factor presence requires gastric biopsies. Here, we evaluate the H. pylori recomLine test for risk stratification of infected patients by comparing the test score and immune recognition of type I or type II strains defined by the virulence factors CagA, VacA, GroEL, UreA, HcpC, and gGT with patient’s disease status according to histology. Moreover, the immune responses of eradicated individuals from two different populations were analysed. Their immune response frequencies and intensities against all antigens except CagA declined below the detection limit. CagA was particularly long lasting in both independent populations. An isolated CagA band often represents past eradication with a likelihood of 88.7%. In addition, a high recomLine score was significantly associated with high-grade gastritis, atrophy, intestinal metaplasia, and gastric cancer. Thus, the recomLine is a sensitive and specific noninvasive test for detecting serum responses against H. pylori in actively infected and eradicated individuals. Moreover, it allows stratifying patients according to their disease state.

  19. Validation of a Novel Immunoline Assay for Patient Stratification according to Virulence of the Infecting Helicobacter pylori Strain and Eradication Status.

    Science.gov (United States)

    Formichella, Luca; Romberg, Laura; Meyer, Hannelore; Bolz, Christian; Vieth, Michael; Geppert, Michael; Göttner, Gereon; Nölting, Christina; Schepp, Wolfgang; Schneider, Arne; Ulm, Kurt; Wolf, Petra; Holster, Ingrid Lisanne; Kuipers, Ernst J; Birkner, Bernd; Soutschek, Erwin; Gerhard, Markus

    2017-01-01

    Helicobacter pylori infection shows a worldwide prevalence of around 50%. However, only a minority of infected individuals develop clinical symptoms or diseases. The presence of H. pylori virulence factors, such as CagA and VacA, has been associated with disease development, but assessment of virulence factor presence requires gastric biopsies. Here, we evaluate the H. pylori recomLine test for risk stratification of infected patients by comparing the test score and immune recognition of type I or type II strains defined by the virulence factors CagA, VacA, GroEL, UreA, HcpC, and gGT with patient's disease status according to histology. Moreover, the immune responses of eradicated individuals from two different populations were analysed. Their immune response frequencies and intensities against all antigens except CagA declined below the detection limit. CagA was particularly long lasting in both independent populations. An isolated CagA band often represents past eradication with a likelihood of 88.7%. In addition, a high recomLine score was significantly associated with high-grade gastritis, atrophy, intestinal metaplasia, and gastric cancer. Thus, the recomLine is a sensitive and specific noninvasive test for detecting serum responses against H. pylori in actively infected and eradicated individuals. Moreover, it allows stratifying patients according to their disease state.

  20. Virulence of the Pseudomonas fluorescens clinical strain MFN1032 towards Dictyostelium discoideum and macrophages in relation with type III secretion system

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    Sperandio Daniel

    2012-09-01

    Full Text Available Abstract Background Pseudomonas fluorescens biovar I MFN1032 is a clinical isolate able to grow at 37°C. This strain displays secretion-mediated hemolytic activity involving phospholipase C and cyclolipopeptides, and a cell-associated hemolytic activity distinct from the secreted hemolytic activity. Cell-associated hemolysis is independent of biosurfactant production and remains in a gacA mutant. Disruption of the hrpU-like operon (the basal part of type III secretion system from rhizospheric strains suppresses this activity. We hypothesized that this phenotype could reflect evolution of an ancestral mechanism involved in the survival of this species in its natural niche. In this study, we evaluated the hrpU-like operon’s contribution to other virulence mechanisms using a panel of Pseudomonas strains from various sources. Results We found that MFN1032 inhibited the growth of the amoebae Dictyostelium discoideum and that this inhibition involved the hrpU-like operon and was absent in a gacA mutant. MFN1032 was capable of causing macrophage lysis, if the hrpU-like operon was intact, and this cytotoxicity remained in a gacA mutant. Cell-associated hemolytic activity and macrophage necrosis were found in other P. fluorescens clinical isolates, but not in biocontrol P. fluorescens strains harbouring hrpU-like operon. The growth of Dictyostelium discoideum was inhibited to a different extent by P. fluorescens strains without correlation between this inhibition and hrpU-like operon sequences. Conclusions In P. fluorescens MFN1032, the basal part of type III secretion system plays a role in D. discoideum growth inhibition and macrophage necrosis. The inhibition of D. discoideum growth is dependent on the GacS/GacA system, while cell-associated hemolytic activity and macrophage lysis are not. Virulence against eukaryotic cells based on the hrpU-like operon may be more than just a stochastic evolution of a conserved system dedicated to survival in

  1. Decreased Fitness and Virulence in ST10 Escherichia coli Harboring blaNDM-5 and mcr-1 against a ST4981 Strain with blaNDM-5

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    Yawei Zhang

    2017-06-01

    Full Text Available Although coexistence of blaNDM-5 and mcr-1 in Escherichia coli has been reported, little is known about the fitness and virulence of such strains. Three carbapenem-resistant Escherichia coli (GZ1, GZ2, and GZ3 successively isolated from one patient in 2015 were investigated for microbiological fitness and virulence. GZ1 and GZ2 were also resistant to colistin. To verify the association between plasmids and fitness, growth kinetics of the transconjugants were performed. We also analyzed genomic sequences of GZ2 and GZ3 using PacBio sequencing. GZ1 and GZ2 (ST10 co-harbored blaNDM-5 and mcr-1, while GZ3 (ST4981 carried only blaNDM-5. GZ3 demonstrated significantly more rapid growth (P < 0.001 and overgrew GZ2 with a competitive index of 1.0157 (4 h and 2.5207 (24 h. Increased resistance to serum killing and mice mortality was also identified in GZ3. While GZ2 had four plasmids (IncI2, IncX3, IncHI2, IncFII, GZ3 possessed one plasmid (IncFII. The genetic contexts of blaNDM-5 in GZ2 and GZ3 were identical but inserted into different backbones, IncX3 (102,512 bp and IncFII (91,451 bp, respectively. The growth was not statistically different between the transconjugants with mcr-1 or blaNDM-5 plasmid and recipient (P = 0.6238. Whole genome sequence analysis revealed that 28 virulence genes were specific to GZ3, potentially contributing to increased virulence of GZ3. Decreased fitness and virulence in a mcr-1 and blaNDM-5 co-harboring ST10 E. coli was found alongside a ST4981 strain with only blaNDM-5. Acquisition of mcr-1 or blaNDM-5 plasmid did not lead to considerable fitness costs, indicating the potential for dissemination of mcr-1 and blaNDM-5 in Enterobacteriaceae.

  2. Genetic Virulence Profile of Enteroaggregative Escherichia coli Strains Isolated from Danish Children with Either Acute or Persistent Diarrhea

    DEFF Research Database (Denmark)

    Hebbelstrup Jensen, Betina; Poulsen, Anja; Hebbelstrup Rye Rasmussen, Stig

    2017-01-01

    Enteroaggregative Escherichia coli (EAEC) is frequently found in diarrheal stools worldwide. It has been associated with persistent diarrhea, weight loss, and failure to thrive in children living in developing countries. A number of important EAEC virulence genes are identified; however, their ro...

  3. A virulent strain of deformed wing virus (DWV) of honeybees (Apis mellifera) prevails after Varroa destructor-mediated, or in vitro, transmission.

    Science.gov (United States)

    Ryabov, Eugene V; Wood, Graham R; Fannon, Jessica M; Moore, Jonathan D; Bull, James C; Chandler, Dave; Mead, Andrew; Burroughs, Nigel; Evans, David J

    2014-06-01

    The globally distributed ectoparasite Varroa destructor is a vector for viral pathogens of the Western honeybee (Apis mellifera), in particular the Iflavirus Deformed Wing Virus (DWV). In the absence of Varroa low levels DWV occur, generally causing asymptomatic infections. Conversely, Varroa-infested colonies show markedly elevated virus levels, increased overwintering colony losses, with impairment of pupal development and symptomatic workers. To determine whether changes in the virus population were due Varroa amplifying and introducing virulent virus strains and/or suppressing the host immune responses, we exposed Varroa-naïve larvae to oral and Varroa-transmitted DWV. We monitored virus levels and diversity in developing pupae and associated Varroa, the resulting RNAi response and transcriptome changes in the host. Exposed pupae were stratified by Varroa association (presence/absence) and virus levels (low/high) into three groups. Varroa-free pupae all exhibited low levels of a highly diverse DWV population, with those exposed per os (group NV) exhibiting changes in the population composition. Varroa-associated pupae exhibited either low levels of a diverse DWV population (group VL) or high levels of a near-clonal virulent variant of DWV (group VH). These groups and unexposed controls (C) could be also discriminated by principal component analysis of the transcriptome changes observed, which included several genes involved in development and the immune response. All Varroa tested contained a diverse replicating DWV population implying the virulent variant present in group VH, and predominating in RNA-seq analysis of temporally and geographically separate Varroa-infested colonies, was selected upon transmission from Varroa, a conclusion supported by direct injection of pupae in vitro with mixed virus populations. Identification of a virulent variant of DWV, the role of Varroa in its transmission and the resulting host transcriptome changes furthers our

  4. Pseudomonas aeruginosa quorum-sensing response in the absence of functional LasR and LasI proteins: the case of strain 148, a virulent dolphin isolate.

    Science.gov (United States)

    Morales, Estefanía; González-Valdez, Abigail; Servín-González, Luis; Soberón-Chávez, Gloria

    2017-07-03

    Pseudomonas aeruginosa is an opportunistic pathogen that presents a complex regulatory network called 'quorum-sensing', which is responsible for the transcription of genes coding for several traits implicated in its pathogenicity. Strain 148 is a dolphin isolate that has been shown to produce quorum-sensing-regulated virulence traits and to be virulent in a mouse model, despite the fact that it contains a 20-kbp deletion that eliminates from the chromosome the lasR gene and the lasI promoter. LasR is a key quorum-sensing transcriptional regulator that, when coupled with the autoinducer 3-oxo-dodecanoyl homoserine lactone (3O-C12-HSL) produced by LasI, activates transcription of genes coding for some virulence-associated traits such as elastase, lasI, rhlI and rhlR. RhlR is also a key quorum-sensing transcriptional regulator that, when interacting with the autoinducer butanoyl homoserine lactone (C4-HSL) that is produced by the synthase RhlI, activates the genes involved in the synthesis of some virulence-associated traits, as rhamnolipids and pyocyanin. We describe that in P. aeruginosa 148, the LasR/3O-C12-HSL-independent rhlR transcriptional activation is due to the release of the negative effect of Vfr (a CRP-ortholog) caused by the insertion of an IS element in vfr, and that rhlI transcription is driven from the rhlR promoter, forming the rhlR-I operon. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  5. A virulent strain of deformed wing virus (DWV of honeybees (Apis mellifera prevails after Varroa destructor-mediated, or in vitro, transmission.

    Directory of Open Access Journals (Sweden)

    Eugene V Ryabov

    2014-06-01

    Full Text Available The globally distributed ectoparasite Varroa destructor is a vector for viral pathogens of the Western honeybee (Apis mellifera, in particular the Iflavirus Deformed Wing Virus (DWV. In the absence of Varroa low levels DWV occur, generally causing asymptomatic infections. Conversely, Varroa-infested colonies show markedly elevated virus levels, increased overwintering colony losses, with impairment of pupal development and symptomatic workers. To determine whether changes in the virus population were due Varroa amplifying and introducing virulent virus strains and/or suppressing the host immune responses, we exposed Varroa-naïve larvae to oral and Varroa-transmitted DWV. We monitored virus levels and diversity in developing pupae and associated Varroa, the resulting RNAi response and transcriptome changes in the host. Exposed pupae were stratified by Varroa association (presence/absence and virus levels (low/high into three groups. Varroa-free pupae all exhibited low levels of a highly diverse DWV population, with those exposed per os (group NV exhibiting changes in the population composition. Varroa-associated pupae exhibited either low levels of a diverse DWV population (group VL or high levels of a near-clonal virulent variant of DWV (group VH. These groups and unexposed controls (C could be also discriminated by principal component analysis of the transcriptome changes observed, which included several genes involved in development and the immune response. All Varroa tested contained a diverse replicating DWV population implying the virulent variant present in group VH, and predominating in RNA-seq analysis of temporally and geographically separate Varroa-infested colonies, was selected upon transmission from Varroa, a conclusion supported by direct injection of pupae in vitro with mixed virus populations. Identification of a virulent variant of DWV, the role of Varroa in its transmission and the resulting host transcriptome changes furthers

  6. Comparative genomic analysis of Xanthomonas axonopodis pv. citrumelo F1, which causes citrus bacterial spot disease, and related strains provides insights into virulence and host specificity.

    Science.gov (United States)

    Jalan, Neha; Aritua, Valente; Kumar, Dibyendu; Yu, Fahong; Jones, Jeffrey B; Graham, James H; Setubal, João C; Wang, Nian

    2011-11-01

    Xanthomonas axonopodis pv. citrumelo is a citrus pathogen causing citrus bacterial spot disease that is geographically restricted within the state of Florida. Illumina, 454 sequencing, and optical mapping were used to obtain a complete genome sequence of X. axonopodis pv. citrumelo strain F1, 4.9 Mb in size. The strain lacks plasmids, in contrast to other citrus Xanthomonas pathogens. Phylogenetic analysis revealed that this pathogen is very close to the tomato bacterial spot pathogen X. campestris pv. vesicatoria 85-10, with a completely different host range. We also compared X. axonopodis pv. citrumelo to the genome of citrus canker pathogen X. axonopodis pv. citri 306. Comparative genomic analysis showed differences in several gene clusters, like those for type III effectors, the type IV secretion system, lipopolysaccharide synthesis, and others. In addition to pthA, effectors such as xopE3, xopAI, and hrpW were absent from X. axonopodis pv. citrumelo while present in X. axonopodis pv. citri. These effectors might be responsible for survival and the low virulence of this pathogen on citrus compared to that of X. axonopodis pv. citri. We also identified unique effectors in X. axonopodis pv. citrumelo that may be related to the different host range as compared to that of X. axonopodis pv. citri. X. axonopodis pv. citrumelo also lacks various genes, such as syrE1, syrE2, and RTX toxin family genes, which were present in X. axonopodis pv. citri. These may be associated with the distinct virulences of X. axonopodis pv. citrumelo and X. axonopodis pv. citri. Comparison of the complete genome sequence of X. axonopodis pv. citrumelo to those of X. axonopodis pv. citri and X. campestris pv. vesicatoria provides valuable insights into the mechanism of bacterial virulence and host specificity.

  7. Comparative Genomic Analysis of Xanthomonas axonopodis pv. citrumelo F1, Which Causes Citrus Bacterial Spot Disease, and Related Strains Provides Insights into Virulence and Host Specificity ▿ #

    Science.gov (United States)

    Jalan, Neha; Aritua, Valente; Kumar, Dibyendu; Yu, Fahong; Jones, Jeffrey B.; Graham, James H.; Setubal, João C.; Wang, Nian

    2011-01-01

    Xanthomonas axonopodis pv. citrumelo is a citrus pathogen causing citrus bacterial spot disease that is geographically restricted within the state of Florida. Illumina, 454 sequencing, and optical mapping were used to obtain a complete genome sequence of X. axonopodis pv. citrumelo strain F1, 4.9 Mb in size. The strain lacks plasmids, in contrast to other citrus Xanthomonas pathogens. Phylogenetic analysis revealed that this pathogen is very close to the tomato bacterial spot pathogen X. campestris pv. vesicatoria 85-10, with a completely different host range. We also compared X. axonopodis pv. citrumelo to the genome of citrus canker pathogen X. axonopodis pv. citri 306. Comparative genomic analysis showed differences in several gene clusters, like those for type III effectors, the type IV secretion system, lipopolysaccharide synthesis, and others. In addition to pthA, effectors such as xopE3, xopAI, and hrpW were absent from X. axonopodis pv. citrumelo while present in X. axonopodis pv. citri. These effectors might be responsible for survival and the low virulence of this pathogen on citrus compared to that of X. axonopodis pv. citri. We also identified unique effectors in X. axonopodis pv. citrumelo that may be related to the different host range as compared to that of X. axonopodis pv. citri. X. axonopodis pv. citrumelo also lacks various genes, such as syrE1, syrE2, and RTX toxin family genes, which were present in X. axonopodis pv. citri. These may be associated with the distinct virulences of X. axonopodis pv. citrumelo and X. axonopodis pv. citri. Comparison of the complete genome sequence of X. axonopodis pv. citrumelo to those of X. axonopodis pv. citri and X. campestris pv. vesicatoria provides valuable insights into the mechanism of bacterial virulence and host specificity. PMID:21908674

  8. An interferon inducing porcine reproductive and respiratory syndrome virus vaccine candidate elicits protection against challenge with the heterologous virulent type 2 strain VR-2385 in pigs.

    Science.gov (United States)

    Fontanella, Eve; Ma, Zexu; Zhang, Yanjin; de Castro, Alessandra M M G; Shen, Huigang; Halbur, Patrick G; Opriessnig, Tanja

    2017-01-03

    Achieving consistent protection by vaccinating pigs against porcine reproductive and respiratory syndrome virus (PRRSV) remains difficult. Recently, an interferon-inducing PRRSV vaccine candidate strain A2MC2 was demonstrated to be attenuated and induced neutralizing antibodies. The objective of this study was to determine the efficacy of passage 90 of A2MC2 (A2P90) to protect pigs against challenge with moderately virulent PRRSV strain VR-2385 (92.3% nucleic acid identity with A2MC2) and highly virulent atypical PRRSV MN184 (84.5% nucleic acid identity with A2MC2). Forty 3-week old pigs were randomly assigned to five groups including a NEG-CONTROL group (non-vaccinated, non-challenged), VAC-VR2385 (vaccinated, challenged with strain VR-2385), VR2385 (challenged with strain VR-2385), VAC-MN184 (vaccinated, challenged with strain MN184) and a MN184 group (challenged with MN184 virus). Vaccination was done at 3weeks of age followed by challenge at 8weeks of age. No viremia was detectable in any of the vaccinated pigs; however, by the time of challenge, 15/16 vaccinated pigs had seroconverted based on ELISA and had neutralizing antibodies against a homologous strain with titers ranging from 8 to 128. Infection with VR-2385 resulted in mild-to-moderate clinical disease and lesions. For VR-2385 infected pigs, vaccination significantly lowered PRRSV viremia and nasal shedding by 9days post challenge (dpc), significantly reduced macroscopic lung lesions, and significantly increased the average daily weight gain compared to the non-vaccinated pigs. Infection with MN184 resulted in moderate-to-severe clinical disease and lesions regardless of vaccination status; however, vaccinated pigs had significantly less nasal shedding by dpc 5 compared to non-vaccinated pigs. Under the study conditions, the A2P90 vaccine strain was attenuated without detectable shedding, improved weight gain, and offered protection to the pigs challenged with VR-2385 by reduction of virus load and

  9. Comparative Proteomic Analysis of Mycobacterium tuberculosis Lineage 7 and Lineage 4 Strains Reveals Differentially Abundant Proteins Linked to Slow Growth and Virulence

    Directory of Open Access Journals (Sweden)

    Solomon A. Yimer

    2017-05-01

    Full Text Available In order to decipher the nature of the slowly growing Mycobacterium tuberculosis (M.tuberculosis lineage 7, the differentially abundant proteins in strains of M. tuberculosis lineage 7 and lineage 4 were defined. Comparative proteomic analysis by mass spectrometry was employed to identify, quantitate and compare the protein profiles of strains from the two M. tuberculosis lineages. Label-free peptide quantification of whole cells from M. tuberculosis lineage 7 and 4 yielded the identification of 2825 and 2541 proteins, respectively. A combined total of 2867 protein groups covering 71% of the predicted M. tuberculosis proteome were identified. The abundance of 125 proteins in M. tuberculosis lineage 7 and 4 strains was significantly altered. Notably, the analysis showed that a number of M. tuberculosis proteins involved in growth and virulence were less abundant in lineage 7 strains compared to lineage 4. Five ABC transporter proteins, three phosphate binding proteins essential for inorganic phosphate uptake, and six components of the type 7 secretion system ESX-3 involved in iron acquisition were less abundant in M. tuberculosis lineage 7. This proteogenomic analysis provided an insight into the lineage 7-specific protein profile which may provide clues to understanding the differential properties of lineage 7 strains in terms of slow growth, survival fitness, and pathogenesis.

  10. Protection induced by virus-like particles containing Toxoplasma gondii microneme protein 8 against highly virulent RH strain of Toxoplasma gondii infection.

    Science.gov (United States)

    Lee, Su-Hwa; Kim, Ah-Ra; Lee, Dong-Hun; Rubino, Ilaria; Choi, Hyo-Jick; Quan, Fu-Shi

    2017-01-01

    Toxoplasma gondii (T. gondii) microneme protein 8 (MIC8) represents a novel, functional distinct invasion factor. In this study, we generated virus-like particles (VLPs) targeting Toxoplasma gondii MIC8 for the first time, and investigated the protection against highly virulent RH strain of T. gondii in a mouse model. We found that VLP vaccination induced Toxoplasma gondii-specific IgG and IgG1 antibody responses in the sera. Upon challenge infection with RH strain of T. gondii tachyzoites, vaccinated mice showed a significant increase of both IgG antibodies in sera and IgA antibodies in feces compared to those before challenge, and a rapid expansion of both germinal center B cell (B220+, GL7+) and T cell (CD4+, CD8+) populations. Importantly, intranasally immunized mice showed higher neutralizing antibodies and displayed no proinflammatory cytokine IFN-γ in the spleen. Mice were completely protected from a lethal challenge infection with the highly virulent T. gondii (RH) showing no body weight loss (100% survival). Our study shows the effective protection against T. gondii infection provided by VLPs containing microneme protein 8 of T. gondii, thus indicating a potential T. gondii vaccine candidate.

  11. Effects of double-stranded RNA on virulence of Paecilomyces fumosoroseus (Deuteromycotina: Hyphomycetes against the silverleaf whitefly, Bemisia tabaci strain B (Homoptera: Aleyrodidae

    Directory of Open Access Journals (Sweden)

    Andréia Cristiane Souza Azevedo

    2000-03-01

    Full Text Available Bands of double-stranded RNA (dsRNA were detected in three out of twelve isolates of Paecilomyces fumosoroseus. Identity of these bands was confirmed by RNAse, DNAse and S1 nuclease treatments. The cure of dsRNA for one isolate (P92 was successfully carried out for a single conidium subculture. Isogenic strains, with or without dsRNA, were submitted to virulence tests against the whitefly Bemisia tabaci strain B. In contrast to findings for some phytopathogenic fungi, these dsRNA fragments did not cause hypovirulence in P. fumosoroseus.Bandas de dsRNA foram detectadas em três dos doze isolados de Paecilomyces fumosoroseus. A identidade destas bandas foi provada através de tratamentos com RNAse, DNAse e S1 nuclease. A cura do dsRNA para um dos isolados (P92 foi obtida através do isolamento de colônias monospóricas. Linhagens isogênicas, com e sem dsRNA, foram submetidas ao teste de virulência contra a mosca branca Bemisia tabaci biotipo B. Ao contrário do que ocorre para vários fungos fitopatogênicos, os fragmentos de dsRNA não causaram hipovirulência em P. fumosoroseus.

  12. Highly virulent Beauveria bassiana strains against the two-spotted spider mite, Tetranychus urticae, show no pathogenicity against five phytoseiid mite species.

    Science.gov (United States)

    Wu, Shengyong; Xie, Haicui; Li, Maoye; Xu, Xuenong; Lei, Zhongren

    2016-12-01

    Entomopathogenic fungi and predatory mites can independently contribute to suppressing the two-spotted spider mite, Tetranychus urticae Koch. It is important to assess the risk of possible fungal infections in predators when a combination of them are being considered as a tandem control strategy for suppressing T. urticae. The first part of this study tested 12 Beauveria bassiana isolates for virulence in T. urticae. Strains SCWJ-2, SDDZ-9, LNSZ-26, GZGY-1-3 and WLMQ-32 were found to be the most potent, causing 37.6-49.5% adult corrected mortality at a concentration of 1 × 10(7) m/L conidia 4 days post-treatment. The second part evaluated the pathogenicity of these five strains in five species of predatory phytoseiid mites. The bioassay results indicated that all adult predatory mite mortalities ranged from 7.5 to 9.1% 4 days post-treatment. No viable fungal hyphae were found on predator cadavers. Observations with scanning electron microscopy revealed that conidia were attached to the cuticle of predatory mites within 2-12 h after spraying with strain LNSZ-26, and had germinated within 24-36 h. After 48 h, conidia had gradually been shed from the mites, after none of the conidia had penetrated the cuticular surfaces. In contrast, the germinated conidia successfully penetrated the cuticle of T. urticae, and within 60 h the fungus colonized the mite's body. Our study demonstrated that although several B. bassiana strains displayed a high virulence in T. urticae there was no evident pathogenicity to phytoseiid mites. These findings support the potential use of entomopathogenic fungus in combination with predatory mites in T. urticae control programs.

  13. Heat-killed and γ-irradiated Brucella strain RB51 stimulates enhanced dendritic cell activation, but not function compared with the virulent smooth strain 2308.

    Science.gov (United States)

    Surendran, Naveen; Hiltbold, Elizabeth M; Heid, Bettina; Sriranganathan, Nammalwar; Boyle, Stephen M; Zimmerman, Kurt L; Witonsky, Sharon G

    2010-11-01

    Brucella spp. are Gram-negative, facultative intracellular bacterial pathogens that cause abortion in livestock and undulant fever in humans worldwide. Brucella abortus strain 2308 is a pathogenic strain that affects cattle and humans. Currently, there are no efficacious human vaccines available. However, B. abortus strain RB51, which is approved by the USDA, is a live-attenuated rough vaccine against bovine brucellosis. Live strain RB51 induces protection via CD4(+) and CD8(+) T-cell-mediated immunity. To generate an optimal T-cell response, strong innate immune responses by dendritic cells (DCs) are crucial. Because of safety concerns, the use of live vaccine strain RB51 in humans is limited. Therefore, in this study, we analyzed the differential ability of the same doses of live, heat-killed (HK) and γ-irradiated (IR) strain RB51 in inducing DC activation and function. Smooth strain 2308, live strain RB51 and lipopolysaccharide were used as controls. Studies using mouse bone marrow-derived DCs revealed that, irrespective of viability, strain RB51 induced greater DC activation than smooth strain 2308. Live strain RB51 induced significantly (P≤0.05) higher DC maturation than HK and IR strains, and only live strain RB51-infected DCs (at multiplicity of infection 1:100) induced significant (P≤0.05) tumor necrosis factor-α and interleukin-12 secretion. © 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  14. In vivo influence of in vitro up-regulated genes in the virulence of an APEC strain associated with swollen head syndrome.

    Science.gov (United States)

    de Paiva, Jacqueline Boldrin; da Silva, Livia Pilatti Mendes; Casas, Monique Ribeiro Tiba; Conceição, Rogério Arcuri; Nakazato, Gerson; de Pace, Fernanda; Sperandio, Vanessa; da Silveira, Wanderley Dias

    2016-01-01

    Avian Pathogenic Escherichia coli is responsible for significant economic losses in the poultry industry by causing a range of systemic or localized diseases collectively termed colibacillosis. The virulence mechanisms of these strains that are pathogenic in poultry and possibly pathogenic in humans have not yet been fully elucidated. This work was developed to study if over-expressed genes in a microarray assay could be potentially involved in the pathogenicity of an Avian Pathogenic Escherichia coli strain isolated from a swollen head syndrome case. For this study, five over-expressed genes were selected for the construction of null mutants [flgE (flagellar hook), tyrR (transcriptional regulator), potF (putrescine transporter), yehD (putative adhesin) and bfr (bacterioferritin)]. The constructed mutants were evaluated for their capacity for the adhesion and invasion of in vitro cultured cells, their motility capacity, and their pathogenic potential in one-day-old chickens compared with the wild-type strain (WT). The Δbfr strain showed a decreased adhesion capacity on avian fibroblasts compared with WT, in the presence and absence of alpha-D-mannopyranoside, and the ΔpotF strain showed decreased adhesion only in the absence of alpha-D-mannopyranoside. The ΔtyrR mutant had a reduced ability to invade Hep-2 cells. No mutant showed changes in invading CEC-32 cells. The mutants ΔflgE and ΔtyrR showed a decreased ability to survive in HD-11 cells. The motility of the mutant strains Δbfr, ΔyehD and ΔpotF was increased, while the ΔtyrR mutant showed reduction, and the ΔflgE became non-motile. No mutant strain caused the same mortality of the WT in one-day-old chickens, showing attenuation to different degrees.

  15. EcoR phylogenetic analysis and virulence genotyping of avian pathogenic Escherichia coli strains and Escherichia coli isolates from commercial chicken carcasses in southern Brazil.

    Science.gov (United States)

    Kobayashi, Renata K T; Aquino, Ivani; Ferreira, Ana Lívia da S; Vidotto, Marilda C

    2011-05-01

    Escherichia coli strains designated as avian pathogenic E. coli (APEC) are responsible for avian colibacillosis, an acute and largely systemic disease that promotes significant economic losses in poultry industry worldwide because of mortality increase, medication costs, and condemnation of carcasses. APEC is a subgroup of extraintestinal pathogenic E. coli pathotype, which includes uropathogenic E. coli, neonatal meningitis E. coli, and septicemic E. coli. We isolated E. coli from commercial chicken carcasses in a Brazilian community and compared by polymerase chain reaction-defined phylogenetic group (A, B1, B2, or D) with APEC strains isolated from sick chickens from different poultry farms. A substantial number of strains assigned to phylogenetic E. coli reference collection group B2, which is known to harbor potent extraintestinal human and animal E. coli pathogens, were identified as APEC (26.0%) in both commercial chicken carcasses and retail poultry meat (retail poultry E. coli [RPEC]) (21.25%). The majority of RPEC were classified as group A (35%), whereas the majority of APEC were groups B1 (30.8) and A (27.6%). APEC and RPEC presented the genes pentaplex, iutA, hly, iron, ompT, and iss, but with different virulence profiles. The similarity between APEC and RPEC indicates RPEC as potentially pathogenic strains and supports a possible zoonotic risk for humans.

  16. Over-expression of homologous antigens in a leucine auxotroph of Brucella abortus strain RB51 protects mice against a virulent B. suis challenge.

    Science.gov (United States)

    Rajasekaran, Parthiban; Surendran, Naveen; Seleem, Mohamed N; Sriranganathan, Nammalwar; Schurig, Gerhardt G; Boyle, Stephen M

    2011-04-12

    Infection by members of the Gram-negative bacterial genus Brucella causes brucellosis in a variety of mammals. Brucellosis in swine remains a challenge, as there is no vaccine in the USA approved for use in swine against brucellosis. Here, we developed an improved recombinant Brucella abortus vaccine strain RB51 that could afford protection against Brucella suis infection by over-expressing genes encoding homologous proteins: L7/L12 ribosomal protein, Cu/Zn superoxide dismutase [SOD] and glycosyl-transferase [WboA]. Using strain RB51leuB as a platform and an antibiotic-resistance marker free plasmid, strains RB51leuB/SOD, RB51leuB/SOD/L7/L12 and RB51leuB/SOD/WboA were constructed to over-express the antigens: SOD alone, SOD and ribosomal protein L7/L12 or SOD and glycosyl-transferase, respectively. The ability of these vaccine candidates to protect against a virulent B. suis challenge were evaluated in a mouse model. All vaccine groups protected mice significantly (PBrucella antigens can be over-expressed in strain RB51leuB and elicit protective immune responses against brucellosis. Since the plasmid over-expressing homologous antigens does not carry an antibiotic resistance gene, it complies with federal regulations and therefore could be used to develop safer multi-species vaccines for prevention of brucellosis caused by other species of Brucella. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. Comparative Genomic Analyses of Multiple Pseudomonas Strains Infecting Corylus avellana Trees Reveal the Occurrence of Two Genetic Clusters with Both Common and Distinctive Virulence and Fitness Traits.

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    Simone Marcelletti

    Full Text Available The European hazelnut (Corylus avellana is threatened in Europe by several pseudomonads which cause symptoms ranging from twig dieback to tree death. A comparison of the draft genomes of nine Pseudomonas strains isolated from symptomatic C. avellana trees was performed to identify common and distinctive genomic traits. The thorough assessment of genetic relationships among the strains revealed two clearly distinct clusters: P. avellanae and P. syringae. The latter including the pathovars avellanae, coryli and syringae. Between these two clusters, no recombination event was found. A genomic island of approximately 20 kb, containing the hrp/hrc type III secretion system gene cluster, was found to be present without any genomic difference in all nine pseudomonads. The type III secretion system effector repertoires were remarkably different in the two groups, with P. avellanae showing a higher number of effectors. Homologue genes of the antimetabolite mangotoxin and ice nucleation activity clusters were found solely in all P. syringae pathovar strains, whereas the siderophore yersiniabactin was only present in P. avellanae. All nine strains have genes coding for pectic enzymes and sucrose metabolism. By contrast, they do not have genes coding for indolacetic acid and anti-insect toxin. Collectively, this study reveals that genomically different Pseudomonas can converge on the same host plant by suppressing the host defence mechanisms with the use of different virulence weapons. The integration into their genomes of a horizontally acquired genomic island could play a fundamental role in their evolution, perhaps giving them the ability to exploit new ecological niches.

  18. Genomic insights into a new Citrobacter koseri strain revealed gene exchanges with the virulence-associated Yersinia pestis pPCP1 plasmid

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    Fabrice eArmougom

    2016-03-01

    Full Text Available 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.

  19. Interactions of virulent and avirulent Yersinia ruckeri strains with isolated gill arches and intestinal explants of rainbow trout Oncorhynchus mykiss.

    Science.gov (United States)

    Tobback, E; Hermans, K; Decostere, A; Van den Broeck, W; Haesebrouck, F; Chiers, K

    2010-07-01

    Yersinia ruckeri is the causative agent of enteric redmouth disease leading to significant losses in salmonid aquaculture worldwide. Little information is available on the pathogenesis of this disease. Basic steps in the establishment of an infection include attachment to the epithelium followed by invasion at the portal of entry. In this study, the interactions of Y. ruckeri with the gills and the gut of rainbow trout Oncorhynchus mykiss (Walbaum, 1792) were studied using standardized perfusion models. Virulent and avirulent Y ruckeri isolates appeared to adhere to and invade both tissues without significant differences. For the first time, the gill and gut perfusion models are shown to be suitable to study bacterial invasiveness.

  20. Immunological response to re-infections with clones of the Colombian strain of Trypanosoma cruzi with different degrees of virulence: influence on pathological features during chronic infection in mice

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    Marcos Lazaro da Silva Guerreiro

    2015-06-01

    Full Text Available Re-infections with Trypanosoma cruzi are an aggravating factor for Chagas disease morbidity. The Colombian strain of T. cruzi represents multiclonal populations formed by clonally propagating organisms with different tropisms and degrees of virulence. In the present study, the influence of successive inoculations with clones of the Colombian strain, exhibiting different degrees of virulence, on chronic myocarditis and the humoral and cellular immune responses (Col-C1 high virulence, Col-C8 medium virulence and Col-C5 low virulence were demonstrated. Mice from three groups with a single infection were evaluated during the acute (14th-30th day and chronic phases for 175 days. An immunofluorescence assay, ELISA and delayed type hypersensitivity (DTH cutaneous test were also performed. Mice with a triple infection were studied on the 115th-175th days following first inoculation. The levels of IgM and IgG2a were higher in the animals with a triple infection. DTH showed a higher intensity in the inflammatory infiltrate based on the morphometric analysis during a 48 h period of the triple infection and at 24 h with a single infection. The histopathology of the heart demonstrated significant exacerbation of cardiac inflammatory lesions confirmed by the morphometric test. The humoral responses indicate a reaction to the triple infection, even with clones of the same strain.

  1. Intrahost Diversity of Feline Coronavirus: A Consensus between the Circulating Virulent/Avirulent Strains and the Internal Mutation Hypotheses?

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    Aline S. Hora

    2013-01-01

    Full Text Available To evaluate the most controversial issue concerning current feline coronavirus (FCoV virology, the coexisting hypotheses of the intrahost and interhost origins of feline infectious peritonitis virus (FIPV in regard to the pathogenesis of feline infectious peritonitis (FIP, this study aimed to assess the molecular diversity of the membrane gene FCoVs in 190 samples from 10 cats with signs of FIP and in 5 faecal samples from cats without signs of FIP. All samples from the non-FIP cats and 25.26% of the samples from the FIP cats were positive for the FCoV membrane (M gene. Mutations in this gene consisted of SNP changes randomly scattered among the sequences; few mutations resulted in amino acid changes. No geographic pattern was observed. Of the cats without FIP that harboured FECoV, the amino acid sequence identities for the M gene were 100% among cats (Cats 1–3 from the same cattery, and the overall sequence identity for the M gene was ≥91%. In one cat, two different lineages of FCoV, one enteric and one systemic, were found that segregated apart in the M gene tree. In conclusion, the in vivo mutation transition hypothesis and the circulating high virulent-low virulent FCoV hypothesis have been found to be plausible according to the results obtained from sequencing the M gene.

  2. Intrahost Diversity of Feline Coronavirus: A Consensus between the Circulating Virulent/Avirulent Strains and the Internal Mutation Hypotheses?

    Science.gov (United States)

    Hora, Aline S.; Asano, Karen M.; Guerra, Juliana M.; Mesquita, Ramon G.; Maiorka, Paulo; Richtzenhain, Leonardo J.; Brandão, Paulo E.

    2013-01-01

    To evaluate the most controversial issue concerning current feline coronavirus (FCoV) virology, the coexisting hypotheses of the intrahost and interhost origins of feline infectious peritonitis virus (FIPV) in regard to the pathogenesis of feline infectious peritonitis (FIP), this study aimed to assess the molecular diversity of the membrane gene FCoVs in 190 samples from 10 cats with signs of FIP and in 5 faecal samples from cats without signs of FIP. All samples from the non-FIP cats and 25.26% of the samples from the FIP cats were positive for the FCoV membrane (M) gene. Mutations in this gene consisted of SNP changes randomly scattered among the sequences; few mutations resulted in amino acid changes. No geographic pattern was observed. Of the cats without FIP that harboured FECoV, the amino acid sequence identities for the M gene were 100% among cats (Cats 1–3) from the same cattery, and the overall sequence identity for the M gene was ≥91%. In one cat, two different lineages of FCoV, one enteric and one systemic, were found that segregated apart in the M gene tree. In conclusion, the in vivo mutation transition hypothesis and the circulating high virulent-low virulent FCoV hypothesis have been found to be plausible according to the results obtained from sequencing the M gene. PMID:23589704

  3. [Factors of virulence associated with enteropathogenicity in strains of Aeromonas spp. isolated from children with diarrhea in Mérida, Venezuela].

    Science.gov (United States)

    Longa, Aurora; Vizcaya, Luisa; Nieves, Beatriz; Bravo, Laura; Morier, Luis; Pérez-Schael, Irene; Enrique Cabrera, Luis

    2005-01-01

    The feces of 397 patients with acute diarrheal disease (ADD) and of other 121 patients without diarrea (control group) were studied in the state of Mérida, Venezuela, from June 1993 to December 1994. The genus Aeromonas was identified in patients with ADD in 11.83% and in 5.78% of the patients from the control group. On studying the virulence factors described for Aeromonas (enterotoxin, cytotoxin, hemaglutinins, cellular hydrofibrosity, and hemolytic activity) in the isolated strains, it was detected that all presented at least one of the factors investigated associated with enteropathogenicity. Of the isolated species, Aeromonas caviae was the most frequently identified. All these results suggest that the Aeromonas species are potential enteric pathogens in this population.

  4. Escherichia coli Strains Isolated from the Uteri Horn, Mouth, and Rectum of Bitches Suffering from Pyometra: Virulence Factors, Antimicrobial Susceptibilities, and Clonal Relationships among Strains

    Science.gov (United States)

    Agostinho, Juliana M. A.; de Souza, Andressa; Schocken-Iturrino, Ruben P.; Beraldo, Lívia G.; Borges, Clarissa A.; Ávila, Fernando A.; Marin, José M.

    2014-01-01

    Pyometra is recognized as one of the main causes of disease and death in the bitch, and Escherichia coli is the major pathogen associated with this disease. In this study, 70 E. coli isolates from the uteri horn, mouth, and rectum of bitches suffering from the disease and 43 E. coli isolates from the rectum of clinically healthy bitches were examined for the presence of uropathogenic virulence genes and susceptibility to antimicrobial drugs. DNA profiles of isolates from uteri horn and mouth in bitches with pyometra were compared by REP, ERIC, and BOX-PCR. Virulence gene frequencies detected in isolates from canine pyometra were as follows: 95.7% fim, 27.1% iss, 25.7% hly, 18.5% iuc, and 17.1% usp. Predominant resistance was determined for cephalothin, ampicillin, and nalidixic acid among the isolates from all sites examined. Multidrug resistance was found on ∼50% pyometra isolates. Using the genotypic methods some isolates from uteri, pus, and saliva of the same bitch proved to have identical DNA profiles which is a reason for concern due to the close relationship between household pets and humans. PMID:24734047

  5. Escherichia coli Strains Isolated from the Uteri Horn, Mouth, and Rectum of Bitches Suffering from Pyometra: Virulence Factors, Antimicrobial Susceptibilities, and Clonal Relationships among Strains

    Directory of Open Access Journals (Sweden)

    Juliana M. A. Agostinho

    2014-01-01

    Full Text Available Pyometra is recognized as one of the main causes of disease and death in the bitch, and Escherichia coli is the major pathogen associated with this disease. In this study, 70 E. coli isolates from the uteri horn, mouth, and rectum of bitches suffering from the disease and 43 E. coli isolates from the rectum of clinically healthy bitches were examined for the presence of uropathogenic virulence genes and susceptibility to antimicrobial drugs. DNA profiles of isolates from uteri horn and mouth in bitches with pyometra were compared by REP, ERIC, and BOX-PCR. Virulence gene frequencies detected in isolates from canine pyometra were as follows: 95.7% fim, 27.1% iss, 25.7% hly, 18.5% iuc, and 17.1% usp. Predominant resistance was determined for cephalothin, ampicillin, and nalidixic acid among the isolates from all sites examined. Multidrug resistance was found on ∼50% pyometra isolates. Using the genotypic methods some isolates from uteri, pus, and saliva of the same bitch proved to have identical DNA profiles which is a reason for concern due to the close relationship between household pets and humans.

  6. Influence of the major nitrite transporter NirC on the virulence of a Swollen Head Syndrome avian pathogenic E. coli (APEC) strain.

    Science.gov (United States)

    de Paiva, Jacqueline Boldrin; Leite, Janaína Luisa; da Silva, Livia Pilatti Mendes; Rojas, Thais Cabrera Galvão; de Pace, Fernanda; Conceição, Rogério Arcuri; Sperandio, Vanessa; da Silveira, Wanderley Dias

    2015-01-30

    Avian Pathogenic Escherichia coli (APEC) strains are extra-intestinal E. coli that infect poultry and cause diseases. Nitrite is a central branch-point in bacterial nitrogen metabolism and is used as a cytotoxin by macrophages. Unlike nitric oxide (NO), nitrite cannot diffuse across bacterial membrane cells. The NirC protein acts as a specific channel to facilitate the transport of nitrite into Salmonella and E. coli cells for nitrogen metabolism and cytoplasmic detoxification. NirC is also required for the pathogenicity of Salmonella by downregulating the production of NO by the host macrophages. Based on an in vitro microarray that revealed the overexpression of the nirC gene in APEC strain SCI-07, we constructed a nirC-deficient SCI-07 strain (ΔnirC) and evaluated its virulence potential using in vivo and in vitro assays. The final cumulative mortalities caused by mutant and wild-type (WT) were similar; while the ΔnirC caused a gradual increase in the mortality rate during the seven days recorded, the WT caused mortality up to 24h post-infection (hpi). Counts of the ΔnirC cells in the spleen, lung and liver were higher than those of the WT after 48 hpi but similar at 24 hpi. Although similar number of ΔnirC and WT cells was observed in macrophages at 3 hpi, there was higher number of ΔnirC cells at 16 hpi. The cell adhesion ability of the ΔnirC strain was about half the WT level in the presence and absence of alpha-D-mannopyranoside. These results indicate that the nirC gene influences the pathogenicity of SCI-07 strain. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Phenotypic Characterization of a Novel Virulence-Factor Deletion Strain of Burkholderia mallei That Provides Partial Protection against Inhalational Glanders in Mice.

    Science.gov (United States)

    Bozue, Joel A; Chaudhury, Sidhartha; Amemiya, Kei; Chua, Jennifer; Cote, Christopher K; Toothman, Ronald G; Dankmeyer, Jennifer L; Klimko, Christopher P; Wilhelmsen, Catherine L; Raymond, Jolynn W; Zavaljevski, Nela; Reifman, Jaques; Wallqvist, Anders

    2016-01-01

    Burkholderia mallei (Bm) is a highly infectious intracellular pathogen classified as a category B biological agent by the Centers for Disease Control and Prevention. After respiratory exposure, Bm establishes itself within host macrophages before spreading into major organ systems, which can lead to chronic infection, sepsis, and death. Previously, we combined computational prediction of host-pathogen interactions with yeast two-hybrid experiments and identified novel virulence factor genes in Bm, including BMAA0553, BMAA0728 (tssN), and BMAA1865. In the present study, we used recombinant allelic exchange to construct deletion mutants of BMAA0553 and tssN (ΔBMAA0553 and ΔTssN, respectively) and showed that both deletions completely abrogated virulence at doses of >100 times the LD50 of the wild-type Bm strain. Analysis of ΔBMAA0553- and ΔTssN-infected mice showed starkly reduced bacterial dissemination relative to wild-type Bm, and subsequent in vitro experiments characterized pathogenic phenotypes with respect to intracellular growth, macrophage uptake and phagosomal escape, actin-based motility, and multinucleated giant cell formation. Based on observed in vitro and in vivo phenotypes, we explored the use of ΔTssN as a candidate live-attenuated vaccine. Mice immunized with aerosolized ΔTssN showed a 21-day survival rate of 67% after a high-dose aerosol challenge with the wild-type Bm ATCC 23344 strain, compared to a 0% survival rate for unvaccinated mice. However, analysis of histopathology and bacterial burden showed that while the surviving vaccinated mice were protected from acute infection, Bm was still able to establish a chronic infection. Vaccinated mice showed a modest IgG response, suggesting a limited potential of ΔTssN as a vaccine candidate, but also showed prolonged elevation of pro-inflammatory cytokines, underscoring the role of cellular and innate immunity in mitigating acute infection in inhalational glanders.

  8. Phenotypic characterization of a novel virulence-factor deletion strain of Burkholderia mallei that provides partial protection against inhalational glanders in mice

    Directory of Open Access Journals (Sweden)

    Joel A. Bozue

    2016-02-01

    Full Text Available Burkholderia mallei (Bm is a highly infectious intracellular pathogen classified as a category B biological agent by the Centers for Disease Control and Prevention. After respiratory exposure, Bm establishes itself within host macrophages before spreading into major organ systems, which can lead to chronic infection, sepsis, and death. Previously, we combined computational prediction of host-pathogen interactions with yeast two-hybrid experiments and identified novel virulence factor genes in Bm, including BMAA0553, BMAA0728 (tssN, and BMAA1865. In the present study, we used recombinant allelic exchange to construct deletion mutants of BMAA0553 and tssN (ΔBMAA0553 and ΔTssN, respectively and showed that both deletions completely abrogated virulence at doses of >100 times the LD50 of the wild-type Bm strain. Analysis of ΔBMAA0553- and ΔTssN-infected mice showed starkly reduced bacterial dissemination relative to wild-type Bm, and subsequent in vitro experiments characterized pathogenic phenotypes with respect to intracellular growth, macrophage uptake and phagosomal escape, actin-based motility, and multinucleated giant cell formation. Based on observed in vitro and in vivo phenotypes, we explored the use of ΔTssN as a candidate live-attenuated vaccine. Mice immunized with aerosolized ΔTssN showed a 21-day survival rate of 67% after a high-dose aerosol challenge with the wild-type Bm ATCC 23344 strain, compared to a 0% survival rate for unvaccinated mice. However, analysis of histopathology and bacterial burden showed that while the surviving vaccinated mice were protected from acute infection, Bm was still able to establish a chronic infection. Vaccinated mice showed a modest IgG response, suggesting a limited potential of ΔTssN as a vaccine candidate, but also showed prolonged elevation of pro-inflammatory cytokines, underscoring the role of cellular and innate immunity in mitigating acute infection in inhalational glanders.

  9. Booster vaccination with safe, modified, live-attenuated mutants of Brucella abortus strain RB51 vaccine confers protective immunity against virulent strains of B. abortus and Brucella canis in BALB/c mice.

    Science.gov (United States)

    Truong, Quang Lam; Cho, Youngjae; Kim, Kiju; Park, Bo-Kyoung; Hahn, Tae-Wook

    2015-11-01

    Brucella abortus attenuated strain RB51 vaccine (RB51) is widely used in prevention of bovine brucellosis. Although vaccination with this strain has been shown to be effective in conferring protection against bovine brucellosis, RB51 has several drawbacks, including residual virulence for animals and humans. Therefore, a safe and efficacious vaccine is needed to overcome these disadvantages. In this study, we constructed several gene deletion mutants (ΔcydC, ΔcydD and ΔpurD single mutants, and ΔcydCΔcydD and ΔcydCΔpurD double mutants) of RB51 with the aim of increasing the safety of the possible use of these mutants as vaccine candidates. The RB51ΔcydC, RB51ΔcydD, RB51ΔpurD, RB51ΔcydCΔcydD and RB51ΔcydCΔpurD mutants exhibited significant attenuation of virulence when assayed in murine macrophages in vitro or in BALB/c mice. A single intraperitoneal immunization with RB51ΔcydC, RB51ΔcydD, RB51ΔcydCΔcydD or RB51ΔcydCΔpurD mutants was rapidly cleared from mice within 3 weeks, whereas the RB51ΔpurD mutant and RB51 were detectable in spleens until 4 and 7 weeks, respectively. Vaccination with a single dose of RB51 mutants induced lower protective immunity in mice than did parental RB51. However, a booster dose of these mutants provided significant levels of protection in mice against challenge with either the virulent homologous B. abortus strain 2308 or the heterologous Brucella canis strain 26. In addition, these mutants were found to induce a mixed but T-helper-1-biased humoral and cellular immune response in immunized mice. These data suggest that immunization with a booster dose of attenuated RB51 mutants provides an attractive strategy to protect against either bovine or canine brucellosis.

  10. Virulence-associated gene profiling of Streptococcus suis isolates by PCR

    NARCIS (Netherlands)

    Silva, L.M.G.; Baums, C.G.; Rehm, T.; Wisselink, H.J.; Goethe, R.; Valentin-Weigand, P.

    2006-01-01

    Definition of virulent Streptococcus suis strains is controversial. One successful approach for identification of virulent European strains is differentiation of capsular serotypes (or the corresponding cps types) and subsequent detection of virulence-associated factors, namely the extracellular

  11. [Distribution of phylogenetic groups and virulence factors in CTX-M-15 β-lactamase-producing uropathogenic Escherichia coli strains isolated from patients in the community of Mérida, Venezuela].

    Science.gov (United States)

    Millán, Ysheth; Hernández, Erick; Millán, Beatriz; Araque, María

    2014-01-01

    In this study, the distribution of phylogenetic groups and the genetic detection of virulence factors in CTX-M-15 β-lactamase-producing uropathogenic Escherichia coli (UPEC) strains were analyzed. Twenty eight strains were isolated between January 2009 and July 2011 from patients with urinary tract infection (UTI) who attended the Public Health Laboratory at Mérida, Venezuela. Determination of phylogenetic groups and detection of six virulence genes, fimH, fyuA, kpsMTII, usp, PAI and papAH, were performed by PCR amplification. Fifteen of the 28 isolates were mainly located in the phylogenetic group A, followed by B2 (12/28) and D (1/28). No direct relationship between the severity or recurrence of UTI and the distribution of phylogroups was observed. All studied virulence factors were found in group B2 strains with the highest frequency. The prevalent virulence profile included the combination of three main genes: fimH, kpsMTII and fyuA and, to a lesser extent, the presence of other determinants such as usp, PAI and/or papAH. These results indicate that virulent UPEC incorporated three important properties: adhesion, iron uptake and evasion of phagocytosis, which favored the production of recurrent UTI. This is the first report describing the association of phylogenetic groups with the potential virulence of CTX-M-15 β-lactamase producing UPEC strains in Venezuela. Copyright © 2014 Asociación Argentina de Microbiología. Publicado por Elsevier España. All rights reserved.

  12. 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

    VAGs) infection. Moreover, initial evidence indicates that inVAGs and exVAGs support intestinal colonization. We developed new screening tools to genotypically and phenotypically characterize E. coli isolates originating in humans, domestic pigs, and 17 wild mammal and avian species. We analyzed 317 isolates......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......) and the European hedgehog (Erinaceus europaeus). The prevalence of exVAGs depended on isolation from a specific host. Human uropathogenic E. coli isolates carried exVAGs with the highest prevalence, followed by badger (Meles meles) and roe deer isolates. Adhesion was found to be very diverse. Adhesion was specific...

  13. Response to Bile Salts in Clinical Strains of Acinetobacter baumannii Lacking the AdeABC Efflux Pump: Virulence Associated with Quorum Sensing

    Science.gov (United States)

    López, Maria; Blasco, Lucia; Gato, Eva; Perez, Astrid; Fernández-Garcia, Laura; Martínez-Martinez, Luis; Fernández-Cuenca, Felipe; Rodríguez-Baño, Jesús; Pascual, Alvaro; Bou, German; Tomás, Maria

    2017-01-01

    Introduction: Acinetobacter baumannii is an opportunistic nosocomial pathogen associated with multiple infections. This pathogen usually colonizes (first stage of microbial infection) host tissues that are in contact with the external environment. As one of the sites of entry in human hosts is the gastrointestinal tract, the pathogen must be capable of tolerating bile salts. However, studies analyzing the molecular characteristics involved in the response to bile salts in clinical strains of A. baumannii are scarce. Material and Methods: Microbiological and transcriptional studies (arrays and RT-PCR) in the response to bile salts were carried out in isogenic (A. baumanni ΔadeB ATCC 17978 and A. baumannii ΔadeL ATCC 17978) and clinical strains from clone ST79/PFGE-HUI-1 which is characterized by lacking the AdeABC efflux pump and by overexpression the AdeFGH efflux pump. Results and Discussion: In presence of bile salts, in addition to the glutamate/aspartate transporter were found overexpressed in A. baumannii ΔadeB ATCC 17978, the virulence factors (surface motility, biofilm, and Type VI Secretion System) which are associated with activation of the Quorum Sensing system. Overexpression of these factors was confirmed in clinical strains of clone ST79/PFGE-HUI-1. Conclusions: This the first study about the adaptive response to bile salts investigating the molecular and microbiological characteristics in response to bile salts of an isogenic model of A. baumannii ATCC 17978 and clinical isolates of A. baumannii (clinical strains of ST79/PFGE-HUI-1) lacking the main RND efflux pump (AdeABC). Clinical isolates of A. baumannii lacking the AdeABC efflux pump (clone ST79/PFGE-HUI-1) displayed a new clinical profile (increased invasiveness) possibly associated with the response to stress conditions (such as the presence of bile salts). PMID:28536672

  14. Phase-contrast MRI measurement of systolic cerebrospinal fluid peak velocity (CSFV(peak)) in the aqueduct of Sylvius: a noninvasive tool for measurement of cerebral capacity.

    Science.gov (United States)

    Kolbitsch, C; Schocke, M; Lorenz, I H; Kremser, C; Zschiegner, F; Pfeiffer, K P; Felber, S; Aichner, F; Hörmann, C; Benzer, A

    1999-06-01

    Cerebrospinal fluid (CSF) outflow to intra- and extracranial subarachnoid spaces caused by arterial inflow to the brain predominantly compensates systolic increases in cerebral blood volume. Phase-contrast magnetic resonance imaging is a new tool for noninvasive assessment of CSF displacement by measuring CSF peak velocity (CSFV(Peak)). The authors tested this new tool in an experimental human model of increased intracranial pressure and reduced cerebral capacity by means of continuous positive airway pressure (CPAP) breathing. The authors investigated systolic CSFV(Peak) in the aqueduct of Sylvius in 11 awake, normocapnic (end-tidal carbon dioxide [ET(CO2)] = 40 mmHg) volunteers without CPAP and at two different CPAP levels (6 and 12 cm H2O) by means of electroencephalography-gated phase-contrast magnetic resonance imaging. Administration of 6 cm H2O CPAP did not change systolic CSFV(Peak) (-4.9+/-2.8 cm/s vs. control: -5.1+/-2.7 cm/s), whereas 12 cm H2O CPAP significantly reduced systolic CSFV(Peak) (-4.0+/-1.8 cm/s vs. control: -5.1+/-2.7 cm/s; P aqueduct of Sylvius is a sensitive method for detecting even minor impairment of cerebral capacity caused by experimentally induced increases in intracranial pressure.

  15. Klebsiella pneumoniae asparagine tDNAs are integration hotspots for different genomic islands encoding microcin E492 production determinants and other putative virulence factors present in hypervirulent strains

    Directory of Open Access Journals (Sweden)

    Andrés Esteban Marcoleta

    2016-06-01

    Full Text Available Due to the developing of multi-resistant and invasive hypervirulent strains, Klebsiella pneumoniae has become one of the most urgent bacterial pathogen threats in the last years. Genomic comparison of a growing number of sequenced isolates has allowed the identification of putative virulence factors, proposed to be acquirable mainly through horizontal gene transfer. In particular, those related with synthesizing the antibacterial peptide microcin E492 (MccE492 and salmochelin siderophores were found to be highly prevalent among hypervirulent strains. The determinants for the production of both molecules were first reported as part of a 13-kbp segment of K. pneumoniae RYC492 chromosome, and were cloned and characterized in E. coli. However, the genomic context of this segment in K. pneumoniae remained uncharacterized.In this work we provided experimental and bioinformatics evidence indicating that the MccE492 cluster is part of a highly conserved 23-kbp genomic island (GI named GIE492, that was integrated in a specific asparagine-tRNA gene (asn-tDNA and was found in a high proportion of isolates from liver abscesses sampled around the world. This element resulted to be unstable and its excision frequency increased after treating bacteria with mytomicin C and upon the overexpression of the island-encoded integrase. Besides the MccE492 genetic cluster, it invariably included an integrase-coding gene, at least 7 protein-coding genes of unknown function, and a putative transfer origin that possibly allows this GI to be mobilized through conjugation. In addition, we analyzed the asn-tDNA loci of all the available K. pneumoniae assembled chromosomes to evaluate them as GI-integration sites. Remarkably, 73% of the strains harbored at least one GI integrated in one of the four asn-tDNA present in this species, confirming them as integration hotspots. Each of these tDNAs was occupied with different frequencies, although they were 100% identical. Also, we

  16. Time-course investigation of infection with a low virulent Pasteurella multocida strain in normal and immune-suppressed 12-week-old free-range chickens.

    Science.gov (United States)

    Mbuthia, P G; Njagi, L W; Nyaga, P N; Bebora, L C; Minga, U; Christensen, J P; Olsen, J E

    2011-12-01

    Twelve-week-old indigenous chickens, either immune-suppressed using dexamethasone (IS) or non-immune-suppressed (NIS), were challenged with a low virulent strain, Pasteurella multocida strain NCTC 10322(T), and developed clinical signs and pathological lesions typical of chronic fowl cholera. NIS birds demonstrated much more severe signs of fowl cholera than IS birds. With few exceptions, signs recorded in IS and NIS birds were of the same types, but significantly milder in the IS birds, indicating that immune suppression does not change the course of infection but rather the severity of signs in fowl cholera. P. multocida signals by fluorescent in situ hybridization (FISH) were observed between 1 h and 14 days in the lungs, trachea, air sacs, liver, spleen, bursa of Fabricius and caecal tonsils, while signals from other organs mostly were observed after 24 h. More organs had FISH signals in NIS birds than in IS birds and at higher frequency per organ. Many organs were positive by FISH even 14 days post infection, and it is suggested that these organs may be likely places for long-term carriage of P. multocida following infection. The present study has demonstrated the spread of P. multocida in different tissues in chickens and distribution of lesions associated with chronic fowl cholera, and pointed to a decrease of pathology in IS birds. Since dexamethasone mostly affects heterophils, the study suggests that these cells play a role in the development of lesions associated with chronic fowl cholera in chickens.

  17. Safety and efficacy of Mycoplasma gallisepticum TS-11 vaccine for the protection of layer pullets against challenge with virulent M. gallisepticum R-strain.

    Science.gov (United States)

    Bíró, Judit; Povazsán, J; Korösi, L; Glávits, R; Hufnagel, L; Stipkovits, L

    2005-08-01

    Mycoplasma gallisepticum TS-11 vaccine was studied for its safety and protective ability in 49-day-old M. gallisepticum-free and Mycoplasma synoviae-free commercial Tetra SL layer chickens. Sixty birds were distributed into four groups: 15 were unvaccinated but were challenged with M. gallisepticum R-strain, 15 were vaccinated by eye drop and then challenged with virulent M. gallisepticum R-strain 4 weeks post vaccination, 15 were designated as controls without vaccination and challenge, and 15 received TS-11 vaccine but no challenge. Based on the post-challenge clinical signs, body weight gain, gross pathological examination of air sacs and peritoneum, histological examination of the trachea, lung, spleen and liver, and reisolation of mycoplasmas from inner organs, the TS-11 vaccine is safe and does not produce clinical signs, a major decrease of body weight gain or pathological lesions. Vaccination induced a slight serological response to M. gallisepticum antigen in serum plate agglutination and blocking enzyme-linked immunosorbent assay tests and prevented development clinical signs of airsacculitis, peribronchitis and interstitial pneumonia on M. gallisepticum challenge.

  18. Comparison of virulence-associated in vitro properties of typed strains of Campylobacter jejuni from different sources

    DEFF Research Database (Denmark)

    Coote, J.G.; Stewart-Tull, D.E.S.; Owen, R.J.

    2007-01-01

    mammalian cells. The results were correlated with source of isolation and genetic makeup by amplified fragment length polymorphism (AFLP) typing. The isolates had variable degrees of haemolytic activity against rabbit erythrocytes and cytotoxicity towards CaCo-2, HeLa and Vero cells. The data indicated...... that the haemolytic and cytotoxic activities were due to separate factors. A range of cytotoxicity was exhibited, whereby some strains had no activity against the target cells and others had activity against all three cell lines. Certain strains had activity against CaCo-2 cells but little or no activity against...... the other cells, while others exhibited the opposite phenotype. The data suggested that the cytotoxicity assay with the different cell lines may have detected more than one cytotoxin. A wide variation between isolates was observed for both adherence and invasion with all three cell lines, yet, overall...

  19. Outbreak of Salmonella typhimurium infection traced to contaminated chocolate and caused by a strain lacking the 60-megadalton virulence plasmid.

    OpenAIRE

    Kapperud, G; Gustavsen, S; Hellesnes, I; Hansen, A. H.; Lassen, J; Hirn, J.; Jahkola, M; Montenegro, M A; Helmuth, R

    1990-01-01

    We describe an outbreak of Salmonella typhimurium infection, caused by contaminated chocolate produced by one Norwegian company, which occurred in Norway and Finland in 1987. A total of 349 bacteriologically verified cases were recorded in Norway, and 12 cases were recorded in Finland. There was a predominance of young children among the patients (median age, 6 years), many of whom developed acute hemorrhagic diarrhea. The outbreak strain exhibited a rare phage lysis pattern and a characteris...

  20. Characterization of the virulence, growth temperature and antibiotic resistance of the Campylobacter jejuni IAL 2383 strain isolated from humans

    Science.gov (United States)

    Fonseca, B.B.; Rossi, D.A.; Maia, C.A.; Nalevaiko, P.C.; Melo, R.T.; Cuccato, L.P.; Beletti, M.E.

    2014-01-01

    The objective of this study was to characterize the C. jejuni IAL2383 strain isolated from humans in Brazil. Transcripts for the racR, dnaJ and ciaB genes were found and flaA, plda and cadF genes were present in the genome and bacteria was sensitive to most of the important antimicrobials used to treat humans. C. jejuni IAL2383 is a good experimental model to analyze the interactions with cells. PMID:24948944

  1. Adhesion of Human and Animal Escherichia coli Strains in Association with Their Virulence-Associated Genes and Phylogenetic Origins

    Science.gov (United States)

    Frömmel, Ulrike; Lehmann, Werner; Rödiger, Stefan; Böhm, Alexander; Nitschke, Jörg; Weinreich, Jörg; Groß, Julia; Roggenbuck, Dirk; Zinke, Olaf; Ansorge, Hermann; Vogel, Steffen; Klemm, Per; Wex, Thomas; Schröder, Christian; Wieler, Lothar H.

    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 (exVAGs) infection. Moreover, initial evidence indicates that inVAGs and exVAGs support intestinal colonization. We developed new screening tools to genotypically and phenotypically characterize E. coli isolates originating in humans, domestic pigs, and 17 wild mammal and avian species. We analyzed 317 isolates for the occurrence of 44 VAGs using a novel multiplex PCR microbead assay (MPMA) and for adhesion to four epithelial cell lines using a new adhesion assay. We correlated data for the definition of new adhesion genes. inVAGs were identified only sporadically, particularly in roe deer (Capreolus capreolus) and the European hedgehog ( Erinaceus europaeus). The prevalence of exVAGs depended on isolation from a specific host. Human uropathogenic E. coli isolates carried exVAGs with the highest prevalence, followed by badger (Meles meles) and roe deer isolates. Adhesion was found to be very diverse. Adhesion was specific to cells, host, and tissue, though it was also unspecific. Occurrence of the following VAGs was associated with a higher rate of adhesion to one or more cell lines: afa-dra, daaD, tsh, vat, ibeA, fyuA, mat, sfa-foc, malX, pic, irp2, and papC. In summary, we established new screening methods which enabled us to characterize large numbers of E. coli isolates. We defined reservoirs for potential pathogenic E. coli. We also identified a very broad range of colonization strategies and defined potential new adhesion genes. PMID:23872574

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

    Science.gov (United States)

    Frömmel, Ulrike; Lehmann, Werner; Rödiger, Stefan; Böhm, Alexander; Nitschke, Jörg; Weinreich, Jörg; Groß, Julia; Roggenbuck, Dirk; Zinke, Olaf; Ansorge, Hermann; Vogel, Steffen; Klemm, Per; Wex, Thomas; Schröder, Christian; Wieler, Lothar H; Schierack, Peter

    2013-10-01

    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 (exVAGs) infection. Moreover, initial evidence indicates that inVAGs and exVAGs support intestinal colonization. We developed new screening tools to genotypically and phenotypically characterize E. coli isolates originating in humans, domestic pigs, and 17 wild mammal and avian species. We analyzed 317 isolates for the occurrence of 44 VAGs using a novel multiplex PCR microbead assay (MPMA) and for adhesion to four epithelial cell lines using a new adhesion assay. We correlated data for the definition of new adhesion genes. inVAGs were identified only sporadically, particularly in roe deer (Capreolus capreolus) and the European hedgehog ( Erinaceus europaeus). The prevalence of exVAGs depended on isolation from a specific host. Human uropathogenic E. coli isolates carried exVAGs with the highest prevalence, followed by badger (Meles meles) and roe deer isolates. Adhesion was found to be very diverse. Adhesion was specific to cells, host, and tissue, though it was also unspecific. Occurrence of the following VAGs was associated with a higher rate of adhesion to one or more cell lines: afa-dra, daaD, tsh, vat, ibeA, fyuA, mat, sfa-foc, malX, pic, irp2, and papC. In summary, we established new screening methods which enabled us to characterize large numbers of E. coli isolates. We defined reservoirs for potential pathogenic E. coli. We also identified a very broad range of colonization strategies and defined potential new adhesion genes.

  3. Análise das impressões digitais de DNA e de fatores de virulência de linhagens de Helicobacter pylori Analysis of molecular fingerprint and virulence factors of Helicobacter pylori strains

    Directory of Open Access Journals (Sweden)

    Anita P. O. Godoy

    2007-06-01

    outcome of the infection is related to several factors, among them bacterial ones such as cagA and vacA s1m1 genotype. Random amplified polymorphic DNA (RAPD-PCR, has been used to generate DNA fingerprints to evaluate similarity among strains within a bacterial species. AIM: To assess the association between RAPD fingerprinting, virulence factors and the disease. METHODS: H. pylori was isolated from 112 patients (41 with gastritis; 19 with gastric ulcers; 38 with duodenal ulcer disease; and 14 with gastroesophageal reflux disease. Allelic variants of cagA and vacA were identified using the polymerase chain reaction (PCR and the fingerprints were generated by RAPD-PCR. RESULTS: There was a strong association between the genotype vacA s1m1 and duodenal ulcers. Although RADP-PCR is a very useful tool in genotyping H. pylori, no significant correlation between the diseases studied and DNA fingerprint was detected neither with fingerprint and different vacA and, cagA genotypes. CONCLUSIONS: The extension of our analysis to patients with well-characterized gastric diseases may provide significant information on the relationship between vacA genotypes and clinical outcomes of H. pylori infection.

  4. Characterization of a new partitivirus strain in Verticillium dahliae provides further evidence of the spread of the highly virulent defoliating pathotype through new introductions

    Directory of Open Access Journals (Sweden)

    Mari Carmen CAÑIZARES

    2015-12-01

    Full Text Available The soilborne pathogen Verticillium dahliae, causal agent of Verticillium wilt, has a worldwide distribution and many hosts of agronomic value. The worldwide spread of a highly virulent defoliating (D pathotype has greatly increased the threat posed by V. dahliae in olive trees. For effective disease management, it is important to know if the D pathotype is spreading long distances from contaminated material, or if D pathotype isolates may have originated locally from native V. dahliae populations several times. We identified a double-stranded RNA mycovirus in an olive D pathotype isolate from Turkey. Sequencing and phylogenetic analysis clustered the virus with members of the family Partitiviridae. The virus was most similar to a partitivirus previously identified in a V. dahliae isolate from cotton in China (VdPV1, with sequence identities of 94% and 91% at the nucleotide level for RNA1 and RNA2, respectively. The virus therefore corresponded to a strain of the established species, and we designated it VdPV1-ol (VdPV1 from olive. The identification of the same viral species in these two fungal isolates from geographically distant origins provides evidence of their relationships, supporting the hypothesis of long-distance movement of V. dahliae isolates.

  5. [Investigation of pathogenic phenotypes and virulence determinants of food-borne Salmonella enterica strains in Caenorhabditis elegans animal model].

    Science.gov (United States)

    Aksoy, Deniz; Şen, Ece

    2015-10-01

    Salmonellosis, caused by non-typhoidal Salmonella enterica serovars with the consumption of contaminated food, is one of the leading food-borne disease that makes microbial food safety an important public health issue. This study was performed in order to determine the antibiotic resistance, serotyping, plasmid profiles and pathogenicity potentials of food-borne Salmonella isolates in Caenorhabditis elegans animal model system in Edirne province, located at Thrace region of Turkey. In this study, 32 Salmonella isolates, of which 26 belonged to Infantis, four to Enteritidis, one to Telaviv and one to Kentucky serovars, isolated from chicken carcasses were used. Antibiotic resistance profiles were determined by disc diffusion and broth microdilution methods. A new C.elegans nematode animal model system was used to determine the pathogenicity potential of the isolates. The antibiotic resistance profiles revealed that one (3.1%) isolate was resistant to gentamicin, two (6.2%) to ciprofloxacin, three (9.4%) to ampicillin, 18 (56.3%) to kanamycin, 19 (60.8%) to neomycin, 25 (78.1%) to tetracycline, 25 (78.1%) to trimethoprim, 26 (81.25%) to nalidixic acid, 27 (84.4%) to streptomycin and 32 (100%) to sulfonamide. All of the 32 strains were susceptible to chloramphenicol and ampicillin/sulbactam. High levels of resistance to streptomycin, nalidixic acid, tetracycline, trimethoprim, sulfonamide, kanamycin and neomycin was determined. According to the plasmid analysis, six isolates (18.75%) harboured 1-3 plasmids with sizes between 1.2 and 42.4 kb. In C.elegans nematode animal model system, the time (in days) required to kill 50% (TD50) of nematodes was calculated for each experimental group. TD50 values of the nematode group fed with S.Typhimurium ATCC 14028 that was used as the positive control and another group fed with E.coli OP50 as the negative control were 4.2 ± 0.5 days and 8.0 ± 0.02 days, respectively. TD50 of the groups fed with Salmonella isolates ranged

  6. Comparison of the live-attenuated Japanese encephalitis vaccine SA14-14-2 strain with its pre-attenuated virulent parent SA14 strain: similarities and differences in vitro and in vivo.

    Science.gov (United States)

    Yun, Sang-Im; Song, Byung-Hak; Polejaeva, Irina A; Davies, Christopher J; White, Kenneth L; Lee, Young-Min

    2016-10-01

    Japanese encephalitis virus (JEV) is the main cause of acute viral encephalitis, primarily affecting children and young adults in the Asia-Pacific region. JEV is a vaccine-preventable pathogen, with four types of JE vaccine licensed in different regions of the world. To date, the most common JEV strain used in vaccine development and production is SA14-14-2, an attenuated strain derived from its wild-type parental strain SA14. In this study, we directly compared the phenotypic and genotypic characteristics of SA14 and SA14-14-2 to determine the biological and genetic properties associated with their differential virulence. In susceptible BHK-21 cells, SA14-14-2 grew slightly more slowly and formed smaller plaques than SA14, but unlike SA14, it showed almost no expression of the viral protein NS1', the product of a conserved predicted RNA pseudoknot-mediated ribosomal frameshift. In weanling ICR mice, SA14-14-2 was highly attenuated in terms of both neuroinvasiveness and neurovirulence, with its median lethal doses invariably over five logs higher than those of SA14 when inoculated intramuscularly and intracerebrally. Interestingly, the neurovirulence of SA14-14-2 was dependent on mouse age, with the 1- to 7-day-old mice being highly susceptible and the 14- to 21-day-old mice becoming resistant to intracerebral inoculation. At the genome level, SA14-14-2 differed from SA14 by 57 nucleotides, including one silent G-to-A substitution at position 3599 within the predicted RNA pseudoknot for NS1' synthesis; of the 57 differences, 25 resulted in amino acid substitutions. Our data pave the way for the development of new genetically modified JE vaccines.

  7. Delineating the effect of host environmental signals on a fully virulent strain of Bacillus anthracis using an integrated transcriptomics and proteomics approach

    NARCIS (Netherlands)

    Panda, G.; Basak, T.; Tanwer, P.; Sengupta, S.; Martins dos Santos, V.A.P.; Bhatnagar, R.

    2014-01-01

    Pathogenic bacteria sense the host environment and regulate expression of virulence-related genes. Environmental signals like temperature, bicarbonate/CO2 and glucose induce toxin production in Bacillus anthracis, but the mechanisms by which these signals contribute to virulence and overall

  8. Lichtheimia species exhibit differences in virulence potential.

    Directory of Open Access Journals (Sweden)

    Volker U Schwartze

    Full Text Available Although the number of mucormycosis cases has increased during the last decades, little is known about the pathogenic potential of most mucoralean fungi. Lichtheimia species represent the second and third most common cause of mucormycosis in Europe and worldwide, respectively. To date only three of the five species of the genus have been found to be involved in mucormycosis, namely L. corymbifera, L. ramosa and L. ornata. However, it is not clear whether the clinical situation reflects differences in virulence between the species of Lichtheimia or whether other factors are responsible. In this study the virulence of 46 strains of all five species of Lichtheimia was investigated in chicken embryos. Additionally, strains of the closest-related genus Dichotomocladium were tested. Full virulence was restricted to the clinically relevant species while all strains of L. hyalospora, L. sphaerocystis and Dichotomocladium species were attenuated. Although virulence differences were present in the clinically relevant species, no connection between origin (environmental vs clinical or phylogenetic position within the species was observed. Physiological studies revealed no clear connection of stress resistance and carbon source utilization with the virulence of the strains. Slower growth at 37°C might explain low virulence of L. hyalospora, L. spaherocystis and Dichotomocladium; however, similarly slow growing strains of L. ornata were fully virulent. Thus, additional factors or a complex interplay of factors determines the virulence of strains. Our data suggest that the clinical situation in fact reflects different virulence potentials in the Lichtheimiaceae.

  9. Efficacy evaluation of the C-strain-based vaccines against the subgenotype 2.1d classical swine fever virus emerging in China.

    Science.gov (United States)

    Luo, Yuzi; Ji, Shengwei; Lei, Jian-Lin; Xiang, Guang-Tao; Liu, Yan; Gao, Yao; Meng, Xing-Yu; Zheng, Guanglai; Zhang, En-Yu; Wang, Yimin; Du, Ming-Liang; Li, Yongfeng; Li, Su; He, Xi-Jun; Sun, Yuan; Qiu, Hua-Ji

    2017-03-01

    Classical swine fever (CSF) is a devastating infectious disease of pigs caused by classical swine fever virus (CSFV). The disease has been controlled following extensive vaccination with the lapinized attenuated vaccine C-strain for decades in China. However, frequent CSF outbreaks occurred recently in a large number of C-strain-vaccinated pig farms in China and a new subgenotype 2.1d of CSFV has been reported to be responsible for the outbreaks. Here we analyzed the molecular variations and antigenic differences among the C-strain-based commercial vaccines of different origins from different manufacturers in China, and reevaluated the vaccines against the emerging subgenotype 2.1d strain of CSFV. The results showed that the C-strain adapted to the continuous ST cell line (CST) contain a unique M290K variation on the E2 protein, compared to those of primary BT cells (CBT) or rabbit origin (CRT) and the traditional C-strain sequences available in the GenBank database. Serum neutralization test revealed the antigenic differences between CST and CBT or CRT. Notably, the neutralizing titers of porcine anti-C-strain sera against the CSFV isolate of subgenotype 2.1d were significantly lower than those against C-strain or Shimen strain. The C-strain-vaccinated, subgenotype 2.1d HLJZZ2014 strain-challenged pigs did not show any clinical signs and all survived. However, these pigs displayed mild pathological and histological lesions, and the CSFV viral RNA was detected in the various tissue and blood samples. Taken together, the C-strain-based vaccines of different origins showed molecular variations and antigenic differences, and could provide clinical but not pathological and virological protection against the subgenotype 2.1d CSFV emerging in China. Further investigation is needed to comprehensively assess the efficacy of C-strain of different doses against the subgenotype 2.1d CSFV. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Comparison of the genome sequence of FP9, an attenuated, tissue culture-adapted European strain of Fowlpox virus, with those of virulent American and European viruses.

    Science.gov (United States)

    Laidlaw, Stephen M; Skinner, Michael A

    2004-02-01

    The 266 kbp genome sequence of plaque-purified, tissue culture-adapted, attenuated European Fowlpox virus FP9 has been determined and compared with the 288 kbp sequence of a pathogenic US strain (FPVUS). FP9 carries 244 of the 260 reported FPVUS ORFs (both viruses also have an unreported orthologue of conserved poxvirus gene A14.5L). Relative to FPVUS, FP9 differed by 118 mutations (26 deletions, 15 insertions and 77 base substitutions), affecting FP9 equivalents of 71 FPVUS ORFs. To help to identify mutations involved in adaptation and attenuation, the virulent parent of FP9, HP1, was sequenced at positions where FP9 differed from FPVUS. At 68 positions, FP9 and HP1 sequences were identical, reflecting differences between American and European lineages. Mutations at the remaining 50 positions in FP9 relative to FPVUS and HP1, involving 46 ORFs, therefore accounted for adaptation and attenuation. ORFs deleted during passage included those encoding members of multigene families: 12 ankyrin repeat proteins, three C-type lectin-like proteins, two C4L/C10L-like proteins, one G-protein coupled receptor protein, one V-type Ig domain protein, two N1R/p28 proteins and one EFc family protein. Tandem ORFs encoding Variola virus B22R orthologues were fused by a 5.8 kbp deletion. Single-copy genes disrupted or deleted during passage included those encoding a homologue of murine T10, a conserved DNA/pantothenate metabolism flavoprotein, photolyase, the A-type inclusion protein and an orthologue of vaccinia A47L. Gene assignments have been updated for DNase II/DLAD, binding proteins for IL-18 and interferon-gamma, phospholipid hydroperoxide glutathione peroxidase (PHGPX/GPX-4) and for a highly conserved homologue of ELOVL4.

  11. COMPARATIVE EVALUATION OF THE PROTECTIVE EFFICACY OF DIFFERENT VACCINATION PROGRAMS AGAINST A VIRULENT FIELD STRAIN OF THE NEWCASTLE DISEASE VIRUS IN BROILERS

    Directory of Open Access Journals (Sweden)

    M Sarcheshmei

    Full Text Available ABSTRACT Despite the intensive vaccination programs used for controlling Newcastle disease (ND in the Iranian poultry industry, outbreaks of ND have been reported in poultry farms. This study was conducted to evaluate the effectiveness of vaccines for the protection against ND infection and virus-shedding period of velogenic Newcastle disease virus (vNDV field strain after different immunization schemes. Eight groups of commercial broiler chickens were used. Six groups were vaccinated with different vaccination programs using commercial live and inactivated ND vaccines. All groups, except for group 8, were challenged with a virulent field isolate (104EID50/bird at 28 days of age. Clinical signs, mortality rate and gross lesions were investigated. Antibody titers were assayed by hemagglutination inhibition test and fecal virus shedding was determined for 14 days post challenge (dpc with 3-day intervals by the RT-PCR method. All unvaccinated-challenged control birds died. Vaccination with these ND vaccines protected chickens from clinical disease. The mortality rate in the vaccinated groups was significantly lower than in the positive control group. However, vaccinated chickens shed the challenge virus in fecal samples. Although the different vaccination regimens displayed close degrees of protection against the disease, the best protection was observed in broilers primed with the live B1 vaccine via eye drop simultaneously with inactivated vaccine at 8 days of age and boosted with B1 or LaSota via drinking water on day 18. In conclusion, the currently used vaccines with different vaccination schemes can protect chickens against the disease in areas where ND is endemic, while the spread of the field virus to other flocks cannot be prevented.

  12. Iron, copper, zinc, and manganese transport and regulation in pathogenic Enterobacteria: correlations between strains, site of infection and the relative importance of the different metal transport systems for virulence.

    Science.gov (United States)

    Porcheron, Gaëlle; Garénaux, Amélie; Proulx, Julie; Sabri, Mourad; Dozois, Charles M

    2013-01-01

    For all microorganisms, acquisition of metal ions is essential for survival in the environment or in their infected host. Metal ions are required in many biological processes as components of metalloproteins and serve as cofactors or structural elements for enzymes. However, it is critical for bacteria to ensure that metal uptake and availability is in accordance with physiological needs, as an imbalance in bacterial metal homeostasis is deleterious. Indeed, host defense strategies against infection either consist of metal starvation by sequestration or toxicity by the highly concentrated release of metals. To overcome these host strategies, bacteria employ a variety of metal uptake and export systems and finely regulate metal homeostasis by numerous transcriptional regulators, allowing them to adapt to changing environmental conditions. As a consequence, iron, zinc, manganese, and copper uptake systems significantly contribute to the virulence of many pathogenic bacteria. However, during the course of our experiments on the role of iron and manganese transporters in extraintestinal Escherichia coli (ExPEC) virulence, we observed that depending on the strain tested, the importance of tested systems in virulence may be different. This could be due to the different set of systems present in these strains, but literature also suggests that as each pathogen must adapt to the particular microenvironment of its site of infection, the role of each acquisition system in virulence can differ from a particular strain to another. In this review, we present the systems involved in metal transport by Enterobacteria and the main regulators responsible for their controlled expression. We also discuss the relative role of these systems depending on the pathogen and the tissues they infect.

  13. Serum Metabolomic Profiling of Piglets Infected with Virulent Classical Swine Fever Virus

    Directory of Open Access Journals (Sweden)

    Jishu Shi

    2017-04-01

    Full Text Available Classical swine fever (CSF is a highly contagious swine infectious disease and causes significant economic losses for the pig industry worldwide. The objective of this study was to determine whether small molecule metabolites contribute to the pathogenesis of CSF. Birefly, serum metabolomics of CSFV Shimen strain-infected piglets were analyzed by ultraperformance liquid chromatography/electrospray ionization time-of-flight mass spectrometry (UPLC/ESI-Q-TOF/MS in combination with multivariate statistical analysis. In CSFV-infected piglets at days 3 and 7 post-infection changes were found in metabolites associated with several key metabolic pathways, including tryptophan catabolism and the kynurenine pathway, phenylalanine metabolism, fatty acid and lipid metabolism, the tricarboxylic acid and urea cycles, branched-chain amino acid metabolism, and nucleotide metabolism. Several pathways involved in energy metabolism including fatty acid biosynthesis and β-oxidation, branched-chain amino acid metabolism, and the tricarboxylic acid cycle were significantly inhibited. Changes were also observed in several metabolites exclusively associated with gut microbiota. The metabolomic profiles indicate that CSFV-host gut microbiome interactions play a role in the development of CSF.

  14. Prevalence of virulence factors in Escherichia coli strains isolated from the genital tract of healthy cows Prevalência de fatores de virulência em cepas de Escherichia coli isoladas do trato genital de vacas saudáveis

    Directory of Open Access Journals (Sweden)

    D. Resende

    2007-06-01

    Full Text Available The prevalence of virulence genes expressing fimbriae, production of hemolysin, colicin and aerobactin, was determined in Escherichia coli isolates from healthy cow’s genital tract not showing clinical signs of infection. The presence of fimbriae expression genes (pap, sfa, afa was assayed using specific primers in a polymerase chain reaction; none were detected in any of the isolates. Yet, a prevalence of 90.4%, 69.8%, and 28.5% of virulence factors for colicin, hemolysin and aerobactin respectively, was detected in the isolates. Analysis of the bacterial pathogenicity of isolates from the bovine genital tract may contribute towards the understanding of E. coli behavior.Determinou-se a prevalência dos genes de virulência expressando fimbrias, produção de hemolisina, colicina e aerobactina em cepas de Escherichia coli obtidas do trato genital de vacas saudáveis que não apresentam sinais clínicos indicativos de infecção. A presença dos genes responsáveis pela expressão de fimbrias (pap, sfa, afa foi avaliada através de reação em cadeia da polimerase utilizando primers especificos para cada um dos genes, nenhum deles foi detectado em qualquer uma das cepas isoladas. A prevalência dos fatores de virulência foi de 90,4%, 69,8%, 28,5% para colicina, hemolisina e aerobactina, respectivamente. A análise da patogenicidade das cepas do trato genital pode contribuir para o entendimento do comportamento das cepas de E. coli.

  15. In Vivo Assessment of Growth and Virulence Gene Expression during Commensal and Pathogenic Lifestyles of luxABCDE-Tagged Enterococcus faecalis Strains in Murine Gastrointestinal and Intravenous Infection Models

    Science.gov (United States)

    Casey, Pat G.; Hill, Colin; Diep, Dzung B.; Nes, Ingolf F.

    2013-01-01

    Cytolysin and gelatinase are prominent pathogenicity determinants associated with highly virulent Enterococcus faecalis strains. In an effort to explore the expression profiles of these virulence traits in vivo, we have employed E. faecalis variants expressing the luxABCDE cassette under the control of either the P16S, cytolysin, or gelatinase promoter for infections of Galleria mellonella caterpillars and mice. Systemic infection of G. mellonella with bioluminescence-tagged E. faecalis MMH594 revealed temporal regulation of both gelatinase and cytolysin promoters and demonstrated that these traits were induced in response to the host environment. Gavage of mice pretreated perorally with antibiotics resulted in efficient colonization of the murine gastrointestinal tract (GIT) in a strain-dependent manner, where the commensal baby isolate EF62 was more persistent than the nosocomial isolate MMH594. A highly significant correlation (R2 > 0.94) was found between bioluminescence and the CFU counts in mouse fecal samples. Both strains showed similar preferences for growth and persistence in the ileum, cecum, and colon. Cytolysin expression was uniform in these compartments of the intestinal lumen. In spite of high numbers (109 CFU/g of intestinal matter) in the ileum, cecum, and colon, no evidence of translocation or systemic infection could be observed. In the murine intravenous infection model, cytolysin expression was readily detected in the liver, kidneys, and bladder. At 72 h postinfection, the highest bacterial loads were found in the liver, kidneys, and spleen, with organ-specific expression levels of cytolysin ∼400- and ∼900-fold higher in the spleen and heart, respectively, than in the liver and kidneys. Taken together, this system based on the bioluminescence imaging technology is established as a new, powerful method to monitor the differential regulation of E. faecalis virulence determinants and to study the spatiotemporal course of infection in living

  16. Controlling of CSFV in European wild boar using oral vaccination: a review

    Directory of Open Access Journals (Sweden)

    Sophie eRossi

    2015-10-01

    Full Text Available Classical swine fever (CSF is among the most detrimental diseases for the swine industry worldwide. Infected wild boar populations can play a crucial role in CSF epidemiology and controlling wild reservoirs is of utmost importance for preventing domestic outbreaks. Oral mass vaccination (OMV has been implemented to control CSF in wild boars and limit the spill over to domestic pigs. This retrospective overview of vaccination experiences illustrates the potential for that option. The C-strain live vaccine was confirmed to be highly efficacious and palatable baits were developed for oral delivery in free ranging wild boars. The first field trials were performed in Germany in the 1990’s and allowed deploying oral baits at a large scale. The delivery process was further improved during the 2000’s among different European countries. Optimal deployment has to be early regarding disease emergence and correctly designed regarding the landscape structure and the natural food sources that can compete with oral baits. OMV deployment is also highly dependent on a local veterinary support working closely with hunters, wildlife and forestry agencies. Vaccination has been the most efficient strategy for CSF control in free ranging wild boar when vaccination is wide spread and lasting for a sufficient period of time. Alternative disease control strategies such as intensified hunting or creating physical boundaries such as fences have been, in contrast, seldom satisfactory and reliable. However, monitoring outbreaks has been challenging during and after vaccination deployment since OMV results in a low probability to detect virus-positive animals and the live-vaccine currently available does not allow serological differentiation of infected from vaccinated animals. The development of a new marker vaccine and companion test is thus a promising option for better monitoring outbreaks during OMV deployment as well as help to better determine when to stop

  17. Pseudomonas aeruginosa Virulence Analyzed in a Dictyostelium discoideum Host System

    OpenAIRE

    Cosson, Pierre; Zulianello, Laurence; Join-Lambert, Olivier; Faurisson, François; Gebbie, Leigh; Benghezal, Mohammed; Van Delden, Christian; Kocjancic Curty, Lasta; Köhler, Thilo

    2002-01-01

    Pseudomonas aeruginosa is an important opportunistic pathogen that produces a variety of cell-associated and secreted virulence factors. P. aeruginosa infections are difficult to treat effectively because of the rapid emergence of antibiotic-resistant strains. In this study, we analyzed whether the amoeba Dictyostelium discoideum can be used as a simple model system to analyze the virulence of P. aeruginosa strains. The virulent wild-type strain PAO1 was shown to inhibit growth of D. discoide...

  18. Rapid and simple method by combining FTA™ card DNA extraction with two set multiplex PCR for simultaneous detection of non-O157 Shiga toxin-producing Escherichia coli strains and virulence genes in food samples.

    Science.gov (United States)

    Kim, S A; Park, S H; Lee, S I; Ricke, S C

    2017-12-01

    The aim of this research was to optimize two multiplex polymerase chain reaction (PCR) assays that could simultaneously detect six non-O157 Shiga toxin-producing Escherichia coli (STEC) as well as the three virulence genes. We also investigated the potential of combining the FTA™ card-based DNA extraction with the multiplex PCR assays. Two multiplex PCR assays were optimized using six primer pairs for each non-O157 STEC serogroup and three primer pairs for virulence genes respectively. Each STEC strain specific primer pair only amplified 155, 238, 321, 438, 587 and 750 bp product for O26, O45, O103, O111, O121 and O145 respectively. Three virulence genes were successfully multiplexed: 375 bp for eae, 655 bp for stx1 and 477 bp for stx2. When two multiplex PCR assays were validated with ground beef samples, distinctive bands were also successfully produced. Since the two multiplex PCR examined here can be conducted under the same PCR conditions, the six non-O157 STEC and their virulence genes could be concurrently detected with one run on the thermocycler. In addition, all bands clearly appeared to be amplified by FTA card DNA extraction in the multiplex PCR assay from the ground beef sample, suggesting that an FTA card could be a viable sampling approach for rapid and simple DNA extraction to reduce time and labour and therefore may have practical use for the food industry. Two multiplex polymerase chain reaction (PCR) assays were optimized for discrimination of six non-O157 Shiga toxin-producing Escherichia coli (STEC) and identification of their major virulence genes within a single reaction, simultaneously. This study also determined the successful ability of the FTA™ card as an alternative to commercial DNA extraction method for conducting multiplex STEC PCR assays. The FTA™ card combined with multiplex PCR holds promise for the food industry by offering a simple and rapid DNA sample method for reducing time, cost and labour for detection of STEC in

  19. Comparison of Virulence Gene Identification, Ribosomal Spacer PCR, and Pulsed-Field Gel Electrophoresis for Typing of Staphylococcus aureus Strains Isolated from Cases of Subclinical Bovine Mastitis in the United States.

    Science.gov (United States)

    Adkins, Pamela R F; Middleton, John R; Fox, Lawrence K

    2016-07-01

    Staphylococcus aureus is one of the most important pathogens causing contagious mastitis in dairy cattle worldwide. The objectives of this study were to determine if recently described S. aureus genotype B was present among previously characterized isolates from cases of bovine intramammary infection in the United States and to compare pulsed-field gel electrophoresis (PFGE) to the combination of ribosomal spacer PCR (RS-PCR) and virulence gene identification for typing of S. aureus strains. The hypothesis was that isolates that were previously characterized as contagious would be identified as genotype B and that the results of the two strain-typing methods would be comparable. Isolates were selected from a collection of S. aureus isolates from eight dairy farms. Mammary quarter milk somatic cell count (SCC) and N-acetyl-β-d-gluconaminidase (NAGase) activity data were known and used to evaluate strain pathogenicity. RS-PCR was performed with conventional gel electrophoresis, and PCR was used for toxin gene identification. RS-PCR patterns were associated with a specific virulence gene pattern, as previously reported. Five RS-PCR banding patterns were identified. None of the isolates were characterized as genotype B. No association between RS-PCR types and milk SCC was found; however, NAGase activity was significantly higher in milk from mammary glands infected with RS-PCR banding type 1 (RSP type 1) than in milk from those infected with RSP type 2. The discriminatory power values were 1.0 and 0.46 for PFGE and RS-PCR, respectively. These data suggest that genotype B may have a limited geographic distribution and that PFGE is more discriminatory than RS-PCR performed with conventional gel electrophoresis for typing of S. aureus isolates of bovine origin. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  20. Occurrence of virulence-related sequences and phylogenetic analysis of commensal and pathogenic avian Escherichia coli strains (APEC Ocorrência de seqüências relacionadas com a virulência e análise filogenética de estirpes comensais e patogênicas de Escherichia coli aviário (APEC

    Directory of Open Access Journals (Sweden)

    Tatiana Amabile de Campos

    2008-10-01

    Full Text Available The presence of iron uptake (irp-2, fyuA, sitA, fepC, iucA, adhesion (iha, lpfA O157/O141, lpfA O157/O154, efa, toxB and invasion (inv, ial-related DNA sequences and assignment to the four main Escherichia coli phylogenetic groups (A, B1, B2 e D were determined in 30 commensal E. coli strains isolated from healthy chickens and in 49 APEC strains isolated from chickens presenting clinical signs of septicemia (n=24 swollen head syndrome (n=14 and omphalitis (n=11 by PCR. None of the strains presented DNA sequences related to the inv, ial, efa, and toxB genes. DNA sequences related to lpfA O157/O154, iucA, fepC, and irp-2 genes were significantly found among pathogenic strains, where iucA gene was associated with septicemia and swollen head syndrome and fepC and irp-2 genes were associated with swollen head syndrome strains. Phylogenetic typing showed that commensal and omphalitis strains belonged mainly to phylogenetic Group A and swollen head syndrome to phylogenetic Group D. Septicemic strains were assigned in phylogenetic Groups A and D. These data could suggest that clonal lineage of septicemic APEC strains have a multiple ancestor origin; one from a pathogenic bacteria ancestor and other from a non-pathogenic ancestor that evolved by the acquisition of virulence related sequences through horizontal gene transfer. Swollen head syndrome may constitute a pathogenic clonal group. By the other side, omphalitis strains probably constitute a non-pathogenic clonal group, and could cause omphalitis as an opportunistic infection. The sharing of virulence related sequences by human pathogenic E. coli and APEC strains could indicate that APEC strains could be a source of virulence genes to human strains and could represent a zoonotic risk.A presença de seqüências de DNA associadas à capacidade de captação de ferro (irp-2, fyuA, sitA, fepC, iucA, adesão (iha, lpfA O157/O141, lpfA O157/O154, efa, toxB e de invasão (inv, ial e a classifica

  1. The effects of host age, host nuclear background and temperature on phenotypic effects of the virulent Wolbachia strain popcorn in Drosophila melanogaster.

    OpenAIRE

    Reynolds, K. Tracy; Thomson, Linda J; Ary A Hoffmann

    2003-01-01

    Because of their obligate endosymbiotic nature, Wolbachia strains by necessity are defined by their phenotypic effects upon their host. Nevertheless, studies on the influence of host background and environmental conditions upon the manifestation of Wolbachia effects are relatively uncommon. Here we examine the behavior of the overreplicating Wolbachia strain popcorn in four different Drosophila melanogaster backgrounds at two temperatures. Unlike other strains of Wolbachia in Drosophila, popc...

  2. Acquisition of the Sda1-Encoding Bacteriophage Does Not Enhance Virulence of the Serotype M1 Streptococcus pyogenes Strain SF370

    OpenAIRE

    Venturini, Carola; Ong, Cheryl-Lynn Y.; Gillen, Christine M.; Ben-Zakour, Nouri L.; Maamary, Peter G.; Nizet, Victor; Beatson, Scott A.; Walker, Mark J.

    2013-01-01

    The resurgence of invasive disease caused by Streptococcus pyogenes (group A Streptococcus [GAS]) in the past 30 years has paralleled the emergence and global dissemination of the highly virulent M1T1 clone. The GAS M1T1 clone has diverged from the ancestral M1 serotype by horizontal acquisition of two unique bacteriophages, encoding the potent DNase Sda1/SdaD2 and the superantigen SpeA, respectively. The phage-encoded DNase promotes escape from neutrophil extracellular traps and is linked to...

  3. Extensive genomic diversity and selective conservation of virulence-determinants in enterohemorrhagic Escherichia coli strains of O157 and non-O157 serotypes

    OpenAIRE

    Ogura, Yoshitoshi; Ooka, Tadasuke; Asadulghani,; Terajima, Jun; Nougayr?de, Jean-Philippe; Kurokawa, Ken; Tashiro, Kousuke; Tobe, Toru; Nakayama, Keisuke; Kuhara, Satoru; Oswald, Eric; Watanabe, Haruo; Hayashi, Tetsuya

    2007-01-01

    Background: Enterohemorrhagic Escherichia coli (EHEC) O157 causes severe food-borne illness in humans. The chromosome of O157 consists of 4.1 Mb backbone sequences shared by benign E. coli K-12, and 1.4 Mb O157-specific sequences encoding many virulence determinants, such as Shiga toxin genes (stx genes) and the locus of enterocyte effacement (LEE). Non-O157 EHECs belonging to distinct clonal lineages from O157 also cause similar illness in humans. According to the "parallel" evolution model,...

  4. Staphylococcus hyicus virulence in relation to exudative epidermitis in pigs

    DEFF Research Database (Denmark)

    Wegener, Henrik Caspar; Andresen, Lars Ole; Bille-Hansen, Vivi

    1993-01-01

    Staphylococcus hyicus strains with different phage types, plasmid profiles, and antibiotic resistance patterns were isolated from piglets with exudative epidermitis. The strains could be divided into virulent strains, producing exudative epidermitis, and avirulent strains, producing no dermal...... changes when injected in experimental piglets. The results showed that both virulent and avirulent strains were present simultaneously on diseased piglets. This constitutes a diagnostic problem. Concentrated culture supernatants from nine virulent strains injected in the skin of healthy piglets produced...... a crusting reaction in all piglets. Acanthosis was observed in the histopathological examination of the crustaceous skin. Concentrated culture supernatants from nine avirulent strains produced no macroscopic or microscopic skin changes. Protein profiles from all virulent strains and seven out of nine...

  5. Sample collection of virulent and non-virulent B. anthracis and Y. pestis for bioforensics analysis

    Energy Technology Data Exchange (ETDEWEB)

    Hong-geller, Elizabeth [Los Alamos National Laboratory; Valdez, Yolanda E [Los Alamos National Laboratory; Shou, Yulin [Los Alamos National Laboratory; Yoshida, Thomas M [Los Alamos National Laboratory; Marrone, Babetta L [Los Alamos National Laboratory; Dunbar, John [Los Alamos National Laboratory

    2009-01-01

    Validated sample collection methods are needed for recovery of microbial evidence in the event of accidental or intentional release of biological agents into the environment. To address this need, we evaluated the sample recovery efficiencies of two collection methods -- swabs and wipes -- for both non-virulent and virulent strains of B. anthracis and Y. pestis from four types of non-porous surfaces: two hydrophilic surfaces, stainless steel and glass, and two hydrophobic surfaces, vinyl and plastic. Sample recovery was quantified using Real-time qPCR to assay for intact DNA signatures. We found no consistent difference in collection efficiency between swabs or wipes. Furthermore, collection efficiency was more surface-dependent for virulent strains than non-virulent strains. For the two non-virulent strains, B. anthracis Sterne and Y. pestis A1122, collection efficiency was approximately 100% and 1 %, respectively, from all four surfaces. In contrast, recovery of B. anthracis Ames spores and Y. pestis C092 from vinyl and plastic was generally lower compared to collection from glass or stainless steel, suggesting that surface hydrophobicity may playa role in the strength of pathogen adhesion. The surface-dependent collection efficiencies observed with the virulent strains may arise from strain-specific expression of capsular material or other cell surface receptors that alter cell adhesion to specific surfaces. These findings contribute to validation of standard bioforensics procedures and emphasize the importance of specific strain and surface interactions in pathogen detection.

  6. DIVA vaccine properties of the live chimeric pestivirus strain CP7_E2gif

    DEFF Research Database (Denmark)

    von Rosen, Tanya; Rangelova, Desislava Yordanova; Nielsen, Jens

    2014-01-01

    Live modified vaccines to protect against classical swine fever virus (CSFV), based on chimeric pestiviruses, have been developed to enable serological Differentiation of Infected from Vaccinated Animals (DIVA). In this context, the chimeric virus CP7_E2gif vaccine candidate is unique as it does...... not include any CSFV components. In the present study, the DIVA vaccine properties of CP7_E2gif were evaluated in comparison to the conventional live attenuated Riemser C-strain vaccine. Sera and tonsil samples obtained from pigs immunised with these two vaccines were analysed. No viral RNA was found in serum...... after vaccination with CP7_E2gif, whereas some serum samples from C-strain vaccinated animals were positive. In both vaccinated groups, individual viral RNA-positive tonsil samples were detected in animals euthanised between 7 and 21 days post vaccination. Furthermore, serum samples from these animals...

  7. 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

    Directory of Open Access Journals (Sweden)

    Karina Salvagni Castilla

    2006-06-01

    Full Text Available 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 the liver and spleen of the chickens ten days after infection, although the presence of more than one fimbrial gene can be related to caecal colonization.A distribuição dos genes de virulência sefC, pefA e spvC foi investigada em 110 amostras de Salmonella Enteritidis pertencentes ao fagotipo 4 através da reação em cadeia da polimerase. A influência destes genes na colonização do ceco e invasão do fígado e baço em pintinhos de um dia de idade foi avaliada. Oito amostras foram negativas para o gene spvC, três para o gene pefA e uma amostra para o gene sefC. Estes resultados permitiram a classificação das amostras em quatro genótipos. A presença destes genes não influenciou a invasão da bactéria no fígado e baço das aves dez dias após a infecção, entretanto, a presença de mais de um gene fimbrial pode ter relação com a colonização cecal.

  8. Complement-mediated opsonization of invasive group A Streptococcus pyogenes strain AP53 is regulated by the bacterial two-component cluster of virulence responder/sensor (CovRS) system.

    Science.gov (United States)

    Agrahari, Garima; Liang, Zhong; Mayfield, Jeffrey A; Balsara, Rashna D; Ploplis, Victoria A; Castellino, Francis J

    2013-09-20

    Group A Streptococcus pyogenes (GAS) strain AP53 is a primary isolate from a patient with necrotizing fasciitis. These AP53 cells contain an inactivating mutation in the sensor component of the cluster of virulence (cov) responder (R)/sensor (S) two-component gene regulatory system (covRS), which enhances the virulence of the primary strain, AP53/covR(+)S(-). However, specific mechanisms by which the covRS system regulates the survival of GAS in humans are incomplete. Here, we show a key role for covRS in the regulation of opsonophagocytosis of AP53 by human neutrophils. AP53/covR(+)S(-) cells displayed potent binding of host complement inhibitors of C3 convertase, viz. Factor H (FH) and C4-binding protein (C4BP), which concomitantly led to minimal C3b deposition on AP53 cells, further showing that these plasma protein inhibitors are active on GAS cells. This resulted in weak killing of the bacteria by human neutrophils and a corresponding high death rate of mice after injection of these cells. After targeted allelic alteration of covS(-) to wild-type covS (covS(+)), a dramatic loss of FH and C4BP binding to the AP53/covR(+)S(+) cells was observed. This resulted in elevated C3b deposition on AP53/covR(+)S(+) cells, a high level of opsonophagocytosis by human neutrophils, and a very low death rate of mice infected with AP53/covR(+)S(+). We show that covRS is a critical transcriptional regulator of genes directing AP53 killing by neutrophils and regulates the levels of the receptors for FH and C4BP, which we identify as the products of the fba and enn genes, respectively.

  9. Antimicrobial peptides effectively kill a broad spectrum of Listeria monocytogenes and Staphylococcus aureus strains independently of origin, sub-type, or virulence factor expression

    DEFF Research Database (Denmark)

    Gottlieb, Caroline Trebbien; Thomsen, L.E.; Ingmer, H.

    2008-01-01

    . Hence it is important to determine the natural variation in susceptibility to HDPs to ensure a successful use in clinical treatment regimes. Results Strains of two human bacterial pathogens, Listeria monocytogenes and Staphylococcus aureus, were selected to cover a wide range of origin, sub....... Conclusion Strains of L. monocytogenes and S. aureus were within each species equally sensitive to a range of HDPs despite variations in subtype, origin, and phenotypic behavior. Our results suggest that therapeutic use of HDPs will not be hampered by occurrence of naturally tolerant strains of the two...

  10. The canine distemper epidemic in Serengeti: are lions victims of a new highly virulent canine distemper virus strain, or is pathogen circulation stochasticity to blame?

    Science.gov (United States)

    Guiserix, Micheline; Bahi-Jaber, Narges; Fouchet, David; Sauvage, Frank; Pontier, Dominique

    2007-12-22

    In the year 1994, the Serengeti lion population was decimated by a canine distemper disease outbreak. Retrospective investigations showed that this host population had already been in contact with the pathogen in 1981 without any detected sign of disease. As an alternative to the virus mutation hypothesis to explain this difference in virulences observed in 1981 and 1994, we propose a novel mechanism of disease emergence based on variation in population immunity. We use a stochastic model to show that stochastic fluctuations in pathogen circulation, owing to a low probability of virus transmission from its reservoir to the target host and thereby resulting in variations in the global immunity level of the target host population, can explain the observations made in Serengeti. This mechanism may also be involved in other infectious disease emergences or re-emergences.

  11. Mexican Trypanosoma cruzi (TCI Strains with Different Degrees of Virulence Induce Diverse Humoral and Cellular Immune Responses in a Murine Experimental Infection Model

    Directory of Open Access Journals (Sweden)

    B. Espinoza

    2010-01-01

    Full Text Available It is has been shown that the majority of T. cruzi strains isolated from Mexico belong to the T. cruzi I (TCI. The immune response produced in response to Mexican T. cruzi I strains has not been well characterized. In this study, two Mexican T. cruzi I strains were used to infect Balb/c mice. The Queretaro (TBAR/MX/0000/Queretaro(Qro strain resulted in 100% mortality. In contrast, no mortality was observed in mice infected with the Ninoa (MHOM/MX/1994/Ninoa strain. Both strains produced extended lymphocyte infiltrates in cardiac tissue. Ninoa infection induced a diverse humoral response with a higher variety of immunoglobulin isotypes than were found in Qro-infected mice. Also, a stronger inflammatory TH1 response, represented by IL-12p40, IFNγ, RANTES, MIG, MIP-1β, and MCP-1 production was observed in Qro-infected mice when compared with Ninoa-infected mice. We propose that an exacerbated TH1 immune response is a likely cause of pathological damage observed in cardiac tissue and the primary cause of death in Qro-infected mice.

  12. Complete Genome Sequences of Low-Passage Virulent and High-Passage Avirulent Variants of Pathogenic Leptospira interrogans Serovar Manilae Strain UP-MMC-NIID, Originally Isolated from a Patient with Severe Leptospirosis, Determined Using PacBio Single-Molecule Real-Time Technology.

    Science.gov (United States)

    Satou, Kazuhito; Shimoji, Makiko; Tamotsu, Hinako; Juan, Ayaka; Ashimine, Noriko; Shinzato, Misuzu; Toma, Claudia; Nohara, Toshitsugu; Shiroma, Akino; Nakano, Kazuma; Teruya, Kuniko; Terabayashi, Yasunobu; Ohki, Shun; Koizumi, Nobuo; Okano, Shou; Suzuki, Toshihiko; Hirano, Takashi

    2015-08-13

    Here, we report the complete genome sequences of low-passage virulent and high-passage avirulent variants of pathogenic Leptospira interrogans serovar Manilae strain UP-MMC-NIID, a major causative agent of leptospirosis. While there were no major differences between the genome sequences, the levels of base modifications were higher in the avirulent variant. Copyright © 2015 Satou et al.

  13. Comparative analysis of the virulence characteristics of epidemic methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from Chinese children: ST59 MRSA highly expresses core gene-encoded toxin.

    Science.gov (United States)

    Li, Shipeng; Sun, Jing; Zhang, Jianzhong; Li, Xiangmei; Tao, Xiaoxia; Wang, Lijuan; Sun, Mingjiao; Liu, Yingchao; Li, Juan; Qiao, Yanhong; Yu, Sangjie; Yao, Kaihu; Yang, Yonghong; Shen, Xuzhuang

    2014-02-01

    This study aims to investigate the prevalence of a novel cell wall-anchored protein gene, sasX, and to obtain information on the genetic basis for the pathogenic potential of the MRSA strains isolated from Chinese children. The molecular and virulence characteristics of the clinical strains were analyzed. Twenty-two sequence types (STs) were obtained, with six epidemic clones ST59, ST239, ST1, ST910, ST88, and ST338 accounting for 35.8, 22, 6.6, 6.6, 5.3, and 4.1% respectively. The expression levels of hla, psmα, and RNAIII were higher in ST59 than in other STs (p MRSA isolates. ST239-MRSA-SCCmecIII-t037 (61.5%) was the predominant sasX-positive MRSA clone. The expressions of PSMα and RNAIII were higher in sasX-positive ST239 isolates than in sasX-negative ST239 ones (p MRSA was higher than that by sasX-negative ST239 MRSA (p = 0.008). This study indicated that ST59 was the predominant clone in the MRSA isolates obtained from Chinese children and might have stronger pathogenic potential. The prevalence of the sasX gene in the MRSA isolates from children was relatively low. Furthermore, the sasX gene might be related to the expressions of PSMα and RNAIII and infection invasiveness. © 2013 APMIS Published by John Wiley & Sons Ltd.

  14. 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

    For microbial risk assessment, it is necessary to recognize and predict Virulence of bacterial pathogens, including their ability to contaminate foods. Hazard characterization requires data on strain variability regarding virulence and survival during food processing. Moreover, information on vir...

  15. Protection of pigs against challenge with virulent Streptococcus suis serotype 2 strains by a muramidase-released protein and extracellular factor vaccine

    NARCIS (Netherlands)

    Wisselink, H.J.; Vecht, U.; Stockhofe Zurwieden, N.; Smith, H.E.

    2001-01-01

    The efficacy of a muramidase-released protein (MRP) and extracellular factor (EF) vaccine in preventing infection and disease in pigs challenged either with a homologous or a heterologous Streptococcus suis serotype 2 strain (MRP EF ) was compared with the efficacy of a vaccine containing

  16. Comparative genome analysis of an avirulent and two virulent strains of avian Pasteurella multocida reveals candidate genes involved in fitness and pathogenicity

    Science.gov (United States)

    Fowl cholera is a highly contagious systemic disease affecting wild and domestic birds, frequently resulting in high morbidity and mortality. The causative agent is Pasteurella multocida (P. multocida). The completed genome of P. multocida strain Pm70 has been available for over eleven years and has...

  17. Current status of taxonomic groups of oral streptococci in endocarditis. Can virulence factors discriminate between endocarditis and non-endocarditis strains?

    DEFF Research Database (Denmark)

    Larsen, Tove; Fiehn, Nils-Erik; Gutschik, Ernö

    1999-01-01

    OBJECTIVE: Infective endocarditis is frequently caused by oral streptococci, especially Streptococcus sanguis. In this group, many strains have recently been reclassified on the basis of new taxonomic schemes. The purpose of this study was to classify oral streptococci from patients with infective...

  18. Assessment of virulence potential of uncharacterized Enterococcus faecalis strains using pan genomic approach – Identification of pathogen–specific and habitat-specific genes

    Science.gov (United States)

    Bakshi, Utpal; Sarkar, Munmun; Paul, Sandip; Dutta, Chitra

    2016-01-01

    Enterococcus faecalis, a leading nosocomial pathogen and yet a prominent member of gut microbiome, lacks clear demarcation between pathogenic and non-pathogenic strains at genome level. Here we present the comparative genome analysis of 36 E. faecalis strains with different pathogenic features and from different body-habitats. This study begins by addressing the genome dynamics, which shows that the pan-genome of E. faecalis is still open, though the core genome is nearly saturated. We identified eight uncharacterized strains as potential pathogens on the basis of their co-segregation with reported pathogens in gene presence-absence matrix and Pathogenicity Island (PAI) distribution. A ~7.4 kb genomic-cassette, which is itself a part of PAI, is found to exist in all reported and potential pathogens, but not in commensals and other uncharacterized strains. This region encodes four genes and among them, products of two hypothetical genes are predicted to be intrinsically disordered that may serve as novel targets for therapeutic measures. Exclusive existence of 215, 129, 4 and 1 genes in the blood, gastrointestinal tract, urogenital tract, oral cavity and lymph node derived E. faecalis genomes respectively suggests possible employment of distinct habitat-specific genetic strategies in the adaptation of E. faecalis in human host. PMID:27924951

  19. The 17D-204 Vaccine Strain-Induced Protection against Virulent Yellow Fever Virus Is Mediated by Humoral Immunity and CD4+ but not CD8+ T Cells.

    Directory of Open Access Journals (Sweden)

    Alan M Watson

    2016-07-01

    Full Text Available A gold standard of antiviral vaccination has been the safe and effective live-attenuated 17D-based yellow fever virus (YFV vaccines. Among more than 500 million vaccinees, only a handful of cases have been reported in which vaccinees developed a virulent wild type YFV infection. This efficacy is presumed to be the result of both neutralizing antibodies and a robust T cell response. However, the particular immune components required for protection against YFV have never been evaluated. An understanding of the immune mechanisms that underlie 17D-based vaccine efficacy is critical to the development of next-generation vaccines against flaviviruses and other pathogens. Here we have addressed this question for the first time using a murine model of disease. Similar to humans, vaccination elicited long-term protection against challenge, characterized by high neutralizing antibody titers and a robust T cell response that formed long-lived memory. Both CD4+ and CD8+ T cells were polyfunctional and cytolytic. Adoptive transfer of immune sera or CD4+ T cells provided partial protection against YFV, but complete protection was achieved by transfer of both immune sera and CD4+ T cells. Thus, robust CD4+ T cell activity may be a critical contributor to protective immunity elicited by highly effective live attenuated vaccines.

  20. The usefulness of semi-solid medium in the isolation of highly virulent Leptospira strains from wild rats in an urban area of Fukuoka, Japan.

    Science.gov (United States)

    Saito, Mitsumasa; Villanueva, Sharon Y A M; Masuzawa, Toshiyuki; Haraguchi, Yusuke; Ita, Shuhei; Miyahara, Satoshi; Ozuru, Ryo; Yamaguchi, Takayoshi; Yoshimura, Michinobu; Ikejiri, Mami; Aramaki, Natsumi; Amran, Muhammad Yunus; Muslich, Lisa Tenriesa; Iida, Ken-ichiro; Yanagihara, Yasutake; Gloriani, Nina G; Yoshida, Shin-ichi

    2015-06-01

    Leptospirosis is a worldwide zoonosis. The importance of urban leptospirosis is recognized in Japan: urban rats carry pathogenic leptospires and people acquire these pathogens through contact with surface water or soil contaminated by the urine of the infected animals. To determine the current Leptospira carriage rate in urban rats, 29 wild rats were trapped in the central area of Fukuoka and strains isolated from their kidneys and urine analyzed. When semi-solid Korthof's medium containing 0.1% agar was used for isolation, 72.2% and 30.8% of the kidney and urine cultures, respectively, were found to be Leptospira-positive. The isolates belonged to Leptospira interrogans, and were classified into two groups (serogroups Pomona and Icterohaemorrhagiae) based on the results of gyrB sequence analysis and microscopic agglutination testing (MAT). Strains belonging to serogroup Icterohemorrhagiae grew well in liquid medium. On the other hand, serogroup Pomona isolates multiplied very little in liquid medium, but did grow in a semi-solid medium. Although strains belonging to serogroup Pomona have not been recognized as native to Japan, this strain may be widely distributed in urban rats. Representative strains from each group were found to be highly pathogenic to hamsters. Our findings should serve as a warning that it is still possible to become infected with leptospires from wild rats living in inner cities of Japan. Furthermore, the use of semi-solid medium for culture will improve the isolation rate of leptospires from the kidneys of wild rats. © 2015 The Societies and Wiley Publishing Asia Pty Ltd.

  1. Virulence Attributes of Low-Virulence Organisms

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    Bryan Larsen

    1994-01-01

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

  2. Toxins and virulence factors of enterotoxigenic Escherichia coli associated with strains isolated from indigenous children and international visitors to a rural community in Guatemala.

    Science.gov (United States)

    Torres, O R; González, W; Lemus, O; Pratdesaba, R A; Matute, J A; Wiklund, G; Sack, D A; Bourgeois, A L; Svennerholm, A-M

    2015-06-01

    Diarrhoea remains a common cause of illness in Guatemala, with children suffering most frequently from the disease. This study directly compared the frequency, enterotoxin, and colonization factor (CF) profiles of enterotoxigenic Escherichia coli (ETEC) strains isolated from children living in a rural community in Guatemala and from Western visitors to the same location during the same seasons, using similar detection methodologies. We found that ETEC accounted for 26% of severe cases of diarrhoea in children requiring hospitalization, 15% of diarrhoea in the community, and 29% of travellers' diarrhoea in visitors staying ⩾2 weeks. The toxin and CF patterns of the ETEC strains isolated from both groups differed significantly (P < 0·0005) as determined by χ 2 = 60·39 for CFs and χ 2 = 35 for toxins, while ETEC phenotypes found in Guatemalan children were comparable to those found in children from other areas of the world.

  3. The effects of host age, host nuclear background and temperature on phenotypic effects of the virulent Wolbachia strain popcorn in Drosophila melanogaster.

    Science.gov (United States)

    Reynolds, K Tracy; Thomson, Linda J; Hoffmann, Ary A

    2003-07-01

    Because of their obligate endosymbiotic nature, Wolbachia strains by necessity are defined by their phenotypic effects upon their host. Nevertheless, studies on the influence of host background and environmental conditions upon the manifestation of Wolbachia effects are relatively uncommon. Here we examine the behavior of the overreplicating Wolbachia strain popcorn in four different Drosophila melanogaster backgrounds at two temperatures. Unlike other strains of Wolbachia in Drosophila, popcorn has a major fitness impact upon its hosts. The rapid proliferation of popcorn causes cells to rupture, resulting in the premature death of adult hosts. Apart from this effect, we found that popcorn delayed development time, and host background influenced both this trait and the rate of mortality associated with infection. Temperature influenced the impact of popcorn upon host mortality, with no reduction in life span occurring in flies reared at 19 degrees. No effect upon fecundity was found. Contrary to earlier reports, popcorn induced high levels of incompatibility when young males were used in tests, and CI levels declined rapidly with male age. The population dynamics of popcorn-type infections will therefore depend on environmental temperature, host background, and the age structure of the population.

  4. In vitro markers for virulence in Yersinia ruckeri.

    Science.gov (United States)

    Tobback, E; Decostere, A; Hermans, K; Van den Broeck, W; Haesebrouck, F; Chiers, K

    2010-03-01

    In this study, different traits that have been associated with bacterial virulence were studied in Yersinia ruckeri. Two isolates that had been shown to cause disease and mortality in experimentally infected rainbow trout were compared with five avirulent isolates. Both virulent isolates showed high adhesion to gill and intestinal mucus of rainbow trout, whereas the majority of non-virulent strains demonstrated significantly lower adhesion. A decrease in adherence capability following bacterial treatment with sodium metaperiodate and proteolytic enzymes suggested the involvement of carbohydrates and proteins. All strains were able to adhere to and invade chinook salmon embryo cell line (CHSE-214), fathead minnow epithelial cell line (FHM) and rainbow trout liver cell line (R1). One non-virulent strain was highly adhesive and invasive in the three cell lines, whereas the virulent strains showed moderate adhesive and invasive capacity. The internalization of several isolates was inhibited by colchicine and cytochalasin-D, suggesting that microtubules and microfilaments play a role. For all strains, intracellular survival assays showed a decrease of viable bacteria in the cells 6 h after inoculation, suggesting that Y. ruckeri is not able to multiply or survive inside cultured cells. Analysis of the susceptibility to the bactericidal effect of rainbow trout serum demonstrated that virulent Y. ruckeri strains were serum resistant, whereas non-virulent strains were generally serum sensitive.

  5. Rare Helicobacter pylori Virulence Genotypes in Bhutan.

    Science.gov (United States)

    Matsunari, Osamu; Miftahussurur, Muhammad; Shiota, Seiji; Suzuki, Rumiko; Vilaichone, Ratha-Korn; Uchida, Tomohisa; Ratanachu-ek, Thawee; Tshering, Lotay; Mahachai, Varocha; Yamaoka, Yoshio

    2016-03-02

    Both the prevalence of Helicobacter pylori infection and the incidence of gastric cancer are high in Bhutan. The high incidence of atrophic gastritis and gastric cancer suggest the phylogeographic origin of an infection with a more virulent strain of H. pylori. More than 90% of Bhutanese strains possessed the highly virulent East Asian-type CagA and all strains had the most virulent type of vacA (s1 type). More than half also had multiple repeats in East Asian-type CagA, which are rare in other countries and are reported characteristictly found in assciation with atrophic gastritis and gastric cancer consistent with Bhutanese strains having multiple H. pylori virulence factors associated with an increase in gastric cancer risk. Phylogeographic analyses showed that most Bhutanese strains belonged to the East Asian population type with some strains (17.5%) sharing East Asian and Amerindian components. Only 9.5% belonged to the European type consistant with H. pylori in Bhutan representing an intermediate evolutionary stage between H. pylori from European and East Asian countries.

  6. Structural and Biophysical Characterization of the Mycobacterium tuberculosis Protein Rv0577, a Protein Associated with Neutral Red Staining of Virulent Tuberculosis Strains and Homologue of the Streptomyces coelicolor Protein KbpA

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    Buchko, Garry W.; Echols, Nathaniel; Flynn, E. M.; Ng, Ho-Leung; Stephenson, Sam; Kim, Heungbok; Myler, Peter J.; Terwilliger, Thomas C.; Alber, Tom; Kim, Chang Y.

    2017-07-25

    The 261-residue Mycobacterium tuberculosis protein Rv0577 is a prominent antigen in tuberculosis patients, the responsible component for neutral red staining of virulent strains of M. tuberculosis, a putative component in a methylglyoxal detoxification pathway, and an agonist of toll-like receptor 2. It also has 36% sequence identity to AfsK-binding protein A (KbpA), a component in the complex secondary metabolite pathways in the Streptomycetes genus from which many commercial antibiotics are derived. To gain insight into the biological function of Rv0577 and the family of KpbA kinase regulators, the crystal structure for Rv0577 was determined to a resolution of 1.75 Å (3OXH), binding properties with neutral red and deoxyadenosine (Ado) surveyed, backbone dynamics measured, and thermal stability assayed by CD spectroscopy. The protein is composed of four approximate repeats with an topology arranged radially in consecutive pairs to form two continuous eight-strand -sheets capped on both ends with an -helix. The two -sheets intersect in the center at roughly a right angle and form an asymmetric deep “saddle” on both sides of the protein, saddle one (P11 to A129) and saddle two (L143 to A258), that may serve to bind ligands. NMR chemical shift perturbation experiments show that neutral red binds to Rv0577, further cementing the role of Rv0577 in the neutral red staining of virulent strains of M. tuberculosis. Similar experiments show that adenosine also bind to Rv0577, although less tightly, with estimated dissociation constants of 4.1 ± 0.3 mM for saddle one and > 1 M for saddle two. Heteronuclear steady-state {1H}-15N NOE, T1, and T2 values were generally uniform through-out the sequence with only a few modest pockets of differences suggestive of slightly different motion in loops between -strands in saddle 1. Circular dichroism spectroscopy characterization of the thermal stability of Rv0577 indicated irreversible unfolding upon heating with an estimated

  7. Synergistic effect of various virulence factors leading to high toxicity of environmental V. cholerae non-O1/ non-O139 isolates lacking ctx gene : comparative study with clinical strains.

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    Neha Rajpara

    Full Text Available Vibrio cholerae non-O1/ non-O139 serogroups have been reported to cause sporadic diarrhoea in humans. Cholera toxins have been mostly implicated for hypersecretion of ions and water into the small intestine. Though most of the V. cholerae non-O1/ non-O139 strains lack these cholera toxins, several other innate virulence factors contribute towards their pathogenicity. The environmental isolates may thus act as reservoirs for potential spreading of these virulence genes in the natural environment which may cause the emergence of epidemic-causing organisms.The environmental isolates of vibrios were obtained from water samples, zooplanktons and phytoplanktons, from a village pond in Gandhinagar, Gujarat, India. They were confirmed as Vibrio cholerae non-O1/ non-O139 using standard biochemical and serotyping tests. PCR experiments revealed that the isolates lacked ctxA, ctxB, tcpA, zot and ace genes whereas other pathogenicity genes like toxR, rtxC, hlyA, hapA and prtV were detected in these isolates. Compared with epidemic strain V. cholerae O1 El Tor N16961, culture supernatants from most of these isolates caused higher cytotoxicity to HT29 cells and higher hemolytic, hemagglutinin and protease activities. In rabbit ileal loop assays, the environmental isolates showed only 2-4 folds lesser fluid accumulation in comparison to N16961 and a V. cholerae clinical isolate IDH02365 of 2009. Pulsed Field Gel electrophoresis and Random amplification of Polymorphic DNA indicated that these isolates showed considerable diversity and did not share the same clonal lineage even though they were derived from the same water source. All the isolates showed resistance to one or more antibiotics.Though these environmental isolates lacked the cholera toxins, they seem to have adopted other survival strategies by optimally utilising a diverse array of several other toxins. The current findings indicate the possibility that these isolates could cause some gastroenteric

  8. Pulmonary immunity and durable protection induced by the ID93/GLA-SE vaccine candidate against the hyper-virulent Korean Beijing Mycobacterium tuberculosis strain K.

    Science.gov (United States)

    Cha, Seung Bin; Kim, Woo Sik; Kim, Jong-Seok; Kim, Hongmin; Kwon, Kee Woong; Han, Seung Jung; Cho, Sang-Nae; Coler, Rhea N; Reed, Steven G; Shin, Sung Jae

    2016-04-27

    The majority of tuberculosis (TB) vaccine candidates advanced to clinical trials have been evaluated preclinically using laboratory-adapted strains. However, it has been proposed that challenge with clinical isolates in preclinical vaccine testing could provide further and more practical validation. Here, we tested the ID93/GLA-SE TB vaccine candidate against the clinical Mycobacterium tuberculosis (Mtb) strain K (Mtb K) belonging to the Beijing family, the most prevalent Mtb strain in South Korea. Mice immunized with ID93/GLA-SE exhibited a significant reduction in bacteria and reduced lung inflammation against Mtb K when compared to non-immunized controls. In addition, we analyzed the immune responses in the lungs of ID93/GLA-SE-immunized mice, and showed that ID93/GLA-SE was able to elicit sustained Th1-biased immune responses including antigen-specific multifunctional CD4(+) T cell co-producing IFN-γ, TNF-α, and IL-2 as well as a high magnitude of IFN-γ response for up to 10 weeks post-challenge. Notably, further investigation of T cell subsets in the lung following challenge showed remarkable generation of CD8(+) central memory T cells by ID93/GLA-SE-immunization. Our findings showed that ID93/GLA-SE vaccine confers a high level of robust protection against the hypervirulent Mtb Beijing infection which was characterized by pulmonary Th1-polarized T-cell immune responses. These findings may also provide relevant information for potential utility of this vaccine candidate in East-Asian countries where the Beijing genotype is highly prevalent. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Mice infected with low-virulence strains of Toxoplasma gondii lose their innate aversion to cat urine, even after extensive parasite clearance.

    Science.gov (United States)

    Ingram, Wendy Marie; Goodrich, Leeanne M; Robey, Ellen A; Eisen, Michael B

    2013-01-01

    Toxoplasma gondii chronic infection in rodent secondary hosts has been reported to lead to a loss of innate, hard-wired fear toward cats, its primary host. However the generality of this response across T. gondii strains and the underlying mechanism for this pathogen-mediated behavioral change remain unknown. To begin exploring these questions, we evaluated the effects of infection with two previously uninvestigated isolates from the three major North American clonal lineages of T. gondii, Type III and an attenuated strain of Type I. Using an hour-long open field activity assay optimized for this purpose, we measured mouse aversion toward predator and non-predator urines. We show that loss of innate aversion of cat urine is a general trait caused by infection with any of the three major clonal lineages of parasite. Surprisingly, we found that infection with the attenuated Type I parasite results in sustained loss of aversion at times post infection when neither parasite nor ongoing brain inflammation were detectable. This suggests that T. gondii-mediated interruption of mouse innate aversion toward cat urine may occur during early acute infection in a permanent manner, not requiring persistence of parasite cysts or continuing brain inflammation.

  10. Mice infected with low-virulence strains of Toxoplasma gondii lose their innate aversion to cat urine, even after extensive parasite clearance.

    Directory of Open Access Journals (Sweden)

    Wendy Marie Ingram

    Full Text Available Toxoplasma gondii chronic infection in rodent secondary hosts has been reported to lead to a loss of innate, hard-wired fear toward cats, its primary host. However the generality of this response across T. gondii strains and the underlying mechanism for this pathogen-mediated behavioral change remain unknown. To begin exploring these questions, we evaluated the effects of infection with two previously uninvestigated isolates from the three major North American clonal lineages of T. gondii, Type III and an attenuated strain of Type I. Using an hour-long open field activity assay optimized for this purpose, we measured mouse aversion toward predator and non-predator urines. We show that loss of innate aversion of cat urine is a general trait caused by infection with any of the three major clonal lineages of parasite. Surprisingly, we found that infection with the attenuated Type I parasite results in sustained loss of aversion at times post infection when neither parasite nor ongoing brain inflammation were detectable. This suggests that T. gondii-mediated interruption of mouse innate aversion toward cat urine may occur during early acute infection in a permanent manner, not requiring persistence of parasite cysts or continuing brain inflammation.

  11. Antigenic analysis of classical swine fever virus E2 glycoprotein using pig antibodies identifies residues contributing to antigenic variation of the vaccine C-strain and group 2 strains circulating in China

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    Peng Jinrong

    2010-12-01

    Full Text Available Abstract Background Glycoprotein E2, the immunodominant protein of classical swine fever virus (CSFV, can induce neutralizing antibodies and confer protective immunity in pigs. Our previous phylogenetic analysis showed that subgroup 2.1 viruses branched away from subgroup 1.1, the vaccine C-strain lineage, and became dominant in China. The E2 glycoproteins of CSFV C-strain and recent subgroup 2.1 field isolates are genetically different. However, it has not been clearly demonstrated how this diversity affects antigenicity of the protein. Results Antigenic variation of glycoprotein E2 was observed not only between CSFV vaccine C-strain and subgroup 2.1 strains, but also among strains of the same subgroup 2.1 as determined by ELISA-based binding assay using pig antisera to the C-strain and a representative subgroup 2.1 strain QZ-07 currently circulating in China. Antigenic incompatibility of E2 proteins markedly reduced neutralization efficiency against heterologous strains. Single amino acid substitutions of D705N, L709P, G713E, N723S, and S779A on C-strain recombinant E2 (rE2 proteins significantly increased heterologous binding to anti-QZ-07 serum, suggesting that these residues may be responsible for the antigenic variation between the C-strain and subgroup 2.1 strains. Notably, a G713E substitution caused the most dramatic enhancement of binding of the variant C-strain rE2 protein to anti-QZ-07 serum. Multiple sequence alignment revealed that the glutamic acid residue at this position is conserved within group 2 strains, while the glycine residue is invariant among the vaccine strains, highlighting the role of the residue at this position as a major determinant of antigenic variation of E2. A variant Simpson's index analysis showed that both codons and amino acids of the residues contributing to antigenic variation have undergone similar diversification. Conclusions These results demonstrate that CSFV vaccine C-strain and group 2 strains

  12. Virulence Genotype and Phylogenetic Groups in relation to Chinese ...

    African Journals Online (AJOL)

    Conclusion: PapA and papC are significant VFs with an essential role in contributing to Chinese herb-resistance. Chinese herb-resistance is associated with a shift towards more virulent strains and B2 phylogenetic group. Key words: Escherichia coli; Virulence factors; Phylogenetic group; Chinese herb-resistance.

  13. Isolation, Virulence, and Antimicrobial Resistance of Methicillin-Resistant Staphylococcus aureus (MRSA and Methicillin Sensitive Staphylococcus aureus (MSSA Strains from Oklahoma Retail Poultry Meats

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    Lubna S. Abdalrahman

    2015-05-01

    Full Text Available Staphylococcus aureus is one the top five pathogens causing domestically acquired foodborne illness in the U.S. Only a few studies are available related to the prevalence of S. aureus and MRSA in the U.S. retail poultry industry. The objectives of this study were to determine the prevalence of S. aureus (MSSA and MRSA in retail chicken and turkey meats sold in Tulsa, Oklahoma and to characterize the recovered strains for their antimicrobial resistance and possession of toxin genes. A total of 167 (114 chicken and 53 turkey retail poultry samples were used in this study. The chicken samples included 61 organic samples while the rest of the poultry samples were conventional. The overall prevalence of S. aureus was 57/106 (53.8% in the conventional poultry samples and 25/61 (41% in the organic ones. Prevalence in the turkey samples (64.2% was higher than in the chicken ones (42.1%. Prevalence of S. aureus did not vary much between conventional (43.4% and organic chicken samples (41%. Two chicken samples 2/114 (1.8% were positive for MRSA. PFGE identified the two MRSA isolates as belonging to PFGE type USA300 (from conventional chicken and USA 500 (from organic chicken which are community acquired CA-MRSA suggesting a human based source of contamination. MLST and spa typing also supported this conclusion. A total of 168 Staphylococcus aureus isolates (101 chicken isolates and 67 turkey isolates were screened for their antimicrobial susceptibility against 16 antimicrobials and their possession of 18 different toxin genes. Multidrug resistance was higher in the turkey isolates compared to the chicken ones and the percentage of resistance to most of the antimicrobials tested was also higher among the turkey isolates. The hemolysin hla and hld genes, enterotoxins seg and sei, and leucocidins lukE-lukD were more prevalent in the chicken isolates. The PVL gene lukS-lukF was detected only in chicken isolates including the MRSA ones. In conclusion, S

  14. Inhibitory effect of biofilm-forming Lactobacillus kunkeei strains against virulent Pseudomonas aeruginosa in vitro and in honeycomb moth (Galleria mellonella) infection model.

    Science.gov (United States)

    Berríos, P; Fuentes, J A; Salas, D; Carreño, A; Aldea, P; Fernández, F; Trombert, A N

    2017-11-10

    Biofilms correspond to complex communities of microorganisms embedded in an extracellular polymeric matrix. Biofilm lifestyle predominates in Pseudomonas aeruginosa, an opportunistic Gram negative pathogen responsible for a wide spectrum of infections in humans, plants and animals. In this context, anti-biofilm can be considered a key strategy to control P. aeruginosa infections, thereby more research in the field is required. On the other hand, Lactobacillus species have been described as beneficial due to their anti-biofilm properties and their consequent effect against a wide spectrum of pathogens. In fact, biofilm-forming Lactobacilli seem to be more efficient than their planktonic counterpart to antagonise pathogenic bacteria. In this work, we demonstrated that Lactobacillus kunkeei, a novel Lactobacillus species isolated from honeybee guts, can form biofilms in vitro. In addition, the L. kunkeei biofilm can, in turn, inhibit the formation of P. aeruginosa biofilms. Finally, we found that L. kunkeei strains attenuate infection of P. aeruginosa in the Galleria mellonella model, presumably by affecting P. aeruginosa biofilm formation and/or their stability. Since L. kunkeei presents characteristics of a probiotic, this work provides evidence arguing that the use of this Lactobacillus species in both animals (including insects) and humans could contribute to impair P. aeruginosa biofilm formation.

  15. Passive transfer of virus-specific antibodies confers protection against reproductive failure induced by a virulent strain of porcine reproductive and respiratory syndrome virus and establishes sterilizing immunity.

    Science.gov (United States)

    Osorio, F A; Galeota, J A; Nelson, E; Brodersen, B; Doster, A; Wills, R; Zuckermann, F; Laegreid, W W

    2002-10-10

    Immune mechanisms mediating protective immunity against porcine reproductive and respiratory syndrome virus (PRRSV) are not well understood. The PRRSV-specific humoral immune response has been dismissed as being ineffective and perhaps deleterious for the host. The function of PRRSV antibodies in protective immunity against infection with a highly abortifacient strain of this virus was examined by passive transfer experiments in pregnant swine. All of a group of pregnant gilts (n = 6) that received PRRSV immunoglobulin (Ig) from PRRSV-convalescent, hyperimmune animals were fully protected from reproductive failure as judged by 95% viability of offspring at weaning (15 days of age). On the other hand, the totality of animals in a matched control group (n = 6) receiving anti-pseudorabies virus (PRV) Ig exhibited marked reproductive failure with 4% survival at weaning. Besides protecting the pregnant females from clinical reproductive disease, the passive transfer of PRRSV Ig prevented the challenge virus from infecting the dams and precluded its vertical transmission, as evidenced by the complete absence of infectious PRRSV from the tissues of the dams and lack of infection in their offspring. In summary, these results indicate that PRRSV-Igs are capable of conferring protective immunity against PRRSV and furthermore that these Igs can provide sterilizing immunity in vivo.

  16. Low-dose benznidazole treatment results in parasite clearance and attenuates heart inflammatory reaction in an experimental model of infection with a highly virulent Trypanosoma cruzi strain.

    Science.gov (United States)

    Cevey, Ágata Carolina; Mirkin, Gerardo Ariel; Penas, Federico Nicolás; Goren, Nora Beatriz

    2016-04-01

    Chagas disease, caused by Trypanosoma cruzi, is the main cause of dilated cardiomyopathy in the Americas. Antiparasitic treatment mostly relies on benznidazole (Bzl) due to Nifurtimox shortage or unavailability. Both induce adverse drug effects (ADE) of varied severity in many patients, leading to treatment discontinuation or abandonment. Since dosage may influence ADE, we aimed to assess Bzl efficacy in terms of parasiticidal and anti-inflammatory activity, using doses lower than those previously reported. BALB/c mice infected with the T. cruzi RA strain were treated with different doses of Bzl. Parasitaemia, mortality and weight change were assessed. Parasite load, tissue infiltrates and inflammatory mediators were studied in the heart. Serum creatine kinase (CK) activity was determined as a marker of heart damage. The infection-independent anti-inflammatory properties of Bzl were studied in an in vitro model of LPS-treated cardiomyocyte culture. Treatment with 25 mg/kg/day Bzl turned negative the parasitological parameters, induced a significant decrease in IL-1β, IL-6 and NOS2 in the heart and CK activity in serum, to normal levels. No mortality was observed in infected treated mice. Primary cultured cardiomyocytes treated with Bzl showed that inflammatory mediators were reduced via inhibition of the NF-κB pathway. A Bzl dose lower than that previously reported for treatment of experimental Chagas disease exerts adequate antiparasitic and anti-inflammatory effects leading to parasite clearance and tissue healing. This may be relevant to reassess the dose currently used for the treatment of human Chagas disease, aiming to minimize ADE.

  17. Low-dose benznidazole treatment results in parasite clearance and attenuates heart inflammatory reaction in an experimental model of infection with a highly virulent Trypanosoma cruzi strain

    Directory of Open Access Journals (Sweden)

    Ágata Carolina Cevey

    2016-04-01

    Full Text Available Chagas disease, caused by Trypanosoma cruzi, is the main cause of dilated cardiomyopathy in the Americas. Antiparasitic treatment mostly relies on benznidazole (Bzl due to Nifurtimox shortage or unavailability. Both induce adverse drug effects (ADE of varied severity in many patients, leading to treatment discontinuation or abandonment. Since dosage may influence ADE, we aimed to assess Bzl efficacy in terms of parasiticidal and anti-inflammatory activity, using doses lower than those previously reported. BALB/c mice infected with the T. cruzi RA strain were treated with different doses of Bzl. Parasitaemia, mortality and weight change were assessed. Parasite load, tissue infiltrates and inflammatory mediators were studied in the heart. Serum creatine kinase (CK activity was determined as a marker of heart damage. The infection-independent anti-inflammatory properties of Bzl were studied in an in vitro model of LPS-treated cardiomyocyte culture. Treatment with 25 mg/kg/day Bzl turned negative the parasitological parameters, induced a significant decrease in IL-1β, IL-6 and NOS2 in the heart and CK activity in serum, to normal levels. No mortality was observed in infected treated mice. Primary cultured cardiomyocytes treated with Bzl showed that inflammatory mediators were reduced via inhibition of the NF-κB pathway. A Bzl dose lower than that previously reported for treatment of experimental Chagas disease exerts adequate antiparasitic and anti-inflammatory effects leading to parasite clearance and tissue healing. This may be relevant to reassess the dose currently used for the treatment of human Chagas disease, aiming to minimize ADE.

  18. Molecular epidemiology reveals emergence of a virulent infectious hematopoietic necrosis (IHN) virus strain in wild salmon and its transmission to hatchery fish

    Science.gov (United States)

    Anderson, Eric D.; Engelking, H. Mark; Emmenegger, Eveline J.; Kurath, Gael

    2000-01-01

    Infectious hematopoietic necrosis virus (IHNV) has been known to be a significant salmonid pathogen in the Pacific Northwest of North America for decades. The goal of this study was to characterize the IHNV genetic heterogeneity and viral traffic over time at a study site in the Deschutes River watershed in Oregon, with an emphasis on the epidemiology of IHNV types causing epidemics in wild kokanee Oncorhynchus nerkabetween 1991 and 1995. The study site included kokanee spawning grounds in the Metolius River and Lake Billy Chinook downstream, in which the IHNV epidemics occurred in 2- and 3-year-old kokanee, and the Round Butte Fish Hatchery at the outflow of the lake. Forty-two IHNV isolates collected from this area between 1975 and 1995 were characterized on a genetic basis by ribonuclease (RNase) protection fingerprint analyses of the virus nucleocapsid, glycoprotein, and nonvirion genes. Analysis of the 16 identified composite haplotypes suggested that both virus evolution and introduction of new IHNV strains contributed to the genetic diversity observed. The results indicated that the 1991–1995 epidemics in kokanee from Lake Billy Chinook were due to a newly introduced IHNV type that was first detected in spawning adult kokanee in 1988 and that this virus type was transmitted from the wild kokanee to hatchery fish downstream in 1991. Twelve IHNV haplotypes were found at Round Butte Fish Hatchery, indicating a series of virus displacement events during the 20-year period examined. This work shows that IHNV traffic can be much more complex than was previously recognized, and the results have implications for fisheries management at the hatchery and throughout the watershed.

  19. STUDIES ON NATURAL IMMUNITY TO PNEUMOCOCCUS TYPE III : II. CERTAIN DISTINGUISHING PROPERTIES OF TWO STRAINS OF PNEUMOCOCCUS TYPE III VARYING IN THEIR VIRULENCE FOR RABBITS, AND THE REAPPEARANCE OF THESE PROPERTIES FOLLOWING R-->S RECONVERSION OF THEIR RESPECTIVE ROUGH DERIVATIVES.

    Science.gov (United States)

    Shaffer, M F; Enders, J F; Wu, C J

    1936-07-31

    The results which have been presented show that under the conditions of artificial cultivation at 37 degrees C. definite differences exist between two smooth strains of Pneumococcus Type III both of which are highly virulent for mice by the intraperitoneal route, but which may be sharply distinguished in their virulence for rabbits. These differences consist in the size of the fully developed intact capsule and the interval of time required for its loss. The somewhat smaller capsule of the avirulent strain, well formed and easily demonstrable during the early period of growth, diminishes quickly, while the large capsule of the strain virulent for rabbits is retained for a considerably longer period. Closely correlated with the time at which this reduction of capsule occurs is the appearance of changes in the surface properties of the bacteria which are revealed by a shifting of the range of acid agglutination, susceptibility to clumping in anti-R serum and ingestion by normal adult human polymorphonuclear leucocytes and serum. Since it has been shown that these alterations as growth continues, result in a loss of characteristics which distinguish the strictly type specific, fully capsulated pneumococcus and ultimately lead to a state temporarily approximating that of the completely avirulent R form, and since under the experimental conditions they are inaugurated sooner, advance more rapidly and are more complete in the rabbit avirulent organism, we believe that they may partly account for difference in rabbit virulence of the two strains. In the following paper an attempt has therefore been made to correlate this behavior in vitro with the events attendant upon inoculation into the animal body. The studies of Clark and Ruehl (16), Henrici (17), Bayne-Jones and Adolph (18) and others have demonstrated a marked increase in the size of the bacterial cell associated with the early phases of growth. These authors have dealt chiefly with noncapsulated rod forms and even

  20. Imperfect Vaccination Can Enhance the Transmission of Highly Virulent Pathogens.

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    Andrew F Read

    2015-07-01

    Full Text Available Could some vaccines drive the evolution of more virulent pathogens? Conventional wisdom is that natural selection will remove highly lethal pathogens if host death greatly reduces transmission. Vaccines that keep hosts alive but still allow transmission could thus allow very virulent strains to circulate in a population. Here we show experimentally that immunization of chickens against Marek's disease virus enhances the fitness of more virulent strains, making it possible for hyperpathogenic strains to transmit. Immunity elicited by direct vaccination or by maternal vaccination prolongs host survival but does not prevent infection, viral replication or transmission, thus extending the infectious periods of strains otherwise too lethal to persist. Our data show that anti-disease vaccines that do not prevent transmission can create conditions that promote the emergence of pathogen strains that cause more severe disease in unvaccinated hosts.

  1. Genes from pUM505 plasmid contribute to Pseudomonas aeruginosa virulence.

    Science.gov (United States)

    Rodríguez-Andrade, E; Hernández-Ramírez, K C; Díaz-Peréz, S P; Díaz-Magaña, A; Chávez-Moctezuma, M P; Meza-Carmen, V; Ortíz-Alvarado, R; Cervantes, C; Ramírez-Díaz, M I

    2016-03-01

    The pUM505 plasmid was isolated from a clinical strain of Pseudomonas aeruginosa. This plasmid contains a genomic island with sequence similar to islands found in chromosomes of virulent P. aeruginosa clinical isolates. The objective of this work was to determine whether pUM505 increases the virulence of P. aeruginosa and to identify the genes responsible for this property. First, using the lettuce-leaf model, we found that pUM505 significantly increases the virulence of P. aeruginosa reference strain PAO1. pUM505 also increased the PAO1 virulence in a murine model and increased cytotoxicity of this strain toward HeLa cells. Thus, we generated a pUM505 gene library of 103 clones in the pUCP20 binary vector. The library was transferred to Escherichia coli TOP10 and P. aeruginosa PAO1 to identify genes. The lettuce-leaf model allowed us to identify three recombinant plasmids that increased the virulence of both E. coli and P. aeruginosa strains. These recombinant plasmids also increased the virulence of the PAO1 strain in mice and induced a cytotoxic effect in HeLa cells. Eleven genes were identified in the virulent transformants. Of these genes, only the pUM505 ORF 2 has homology with a gene previously implicated in virulence. These results indicate that pUM505 contains several genes that encode virulence factors, suggesting that the plasmid may contribute directly to bacterial virulence.

  2. Draft genome sequences of two virulent serotypes of avian Pasteurella multocida

    Science.gov (United States)

    Here we report the draft genome sequences of two virulent avian strains of Pasteurella multocida. Comparative analyses of these genomes were done with the published genome sequence of avirulent Pasteurella multocida strain Pm70....

  3. Virulence of Vancomycin-Resistant Enterococcus faecium According to Linezolid Resistance and Clinical Outbreak Status

    OpenAIRE

    McLaughlin, Milena; Malczynski, Michael; Qi, Chao; Barajas, Grace; Radetski, Jordan; Zembower, Teresa; Scheetz, Marc H.

    2013-01-01

    Assessing clinical virulence differences between vancomycin-resistant Enterococcus faecium (VREF) strains resistant to linezolid (LRVRE) and linezolid-susceptible VRE (LSVRE) strains is difficult due to confounding patient variables. Galleria mellonella is a validated host interaction model allowing straightforward organism virulence assessment. The objective of this study was to assess the virulence of VREF in G. mellonella according to linezolid resistance and clinical outbreak status. A ge...

  4. Virulence Analysis of Bacillus cereus Isolated after Death of Preterm Neonates, Nice, France, 2013.

    Science.gov (United States)

    Lotte, Romain; Hérissé, Anne-Laure; Berrouane, Yasmina; Lotte, Laurène; Casagrande, Florence; Landraud, Luce; Herbin, Sabine; Ramarao, Nalini; Boyer, Laurent; Ruimy, Raymond

    2017-05-01

    After the deaths of 2 preterm neonates with Bacillus cereus systemic infection in the same intensive care unit, we investigated the pathogenic potential of this bacterium. Genetic and virulence analysis indicated the neonates were infected with 2 different strains with a virulence potential similar to environmental strains, indicating likely patient immune response failure.

  5. Glucose starvation boosts Entamoeba histolytica virulence.

    Directory of Open Access Journals (Sweden)

    Ayala Tovy

    2011-08-01

    Full Text Available The unicellular parasite, Entamoeba histolytica, is exposed to numerous adverse conditions, such as nutrient deprivation, during its life cycle stages in the human host. In the present study, we examined whether the parasite virulence could be influenced by glucose starvation (GS. The migratory behaviour of the parasite and its capability to kill mammalian cells and to lyse erythrocytes is strongly enhanced following GS. In order to gain insights into the mechanism underlying the GS boosting effects on virulence, we analyzed differences in protein expression levels in control and glucose-starved trophozoites, by quantitative proteomic analysis. We observed that upstream regulatory element 3-binding protein (URE3-BP, a transcription factor that modulates E.histolytica virulence, and the lysine-rich protein 1 (KRiP1 which is induced during liver abscess development, are upregulated by GS. We also analyzed E. histolytica membrane fractions and noticed that the Gal/GalNAc lectin light subunit LgL1 is up-regulated by GS. Surprisingly, amoebapore A (Ap-A and cysteine proteinase A5 (CP-A5, two important E. histolytica virulence factors, were strongly down-regulated by GS. While the boosting effect of GS on E. histolytica virulence was conserved in strains silenced for Ap-A and CP-A5, it was lost in LgL1 and in KRiP1 down-regulated strains. These data emphasize the unexpected role of GS in the modulation of E.histolytica virulence and the involvement of KRiP1 and Lgl1 in this phenomenon.

  6. Toxoplasma gondii: I. Avaliação da virulência de oito amostras

    Directory of Open Access Journals (Sweden)

    Regina Mitsuka

    1998-01-01

    Full Text Available In order to evaluate the virulence and pathogenicity of tachyzoites, eight Toxoplasma gondii strains isolated from different animal species and humans - LIV IV, LIV V e S 11 isolated from swine, RH e VPS from humans, AS 28 from mice, HV III from dog and CN from cat - were inoculated in mice and rabbits. All the strains were strongly virulent for mice. Groups of mice inoculated, intraperitonially, with 10(4 tachyzoites died in an average of 6.0 to 7.8 days, after inoculation. The strains isolated more recently, LIV V and HV III (LD50 of 7 and 15 tachyzoites, respectively were the most virulent. The RH strain showed the lowest virulence, with LD50 of 3160 tachyzoites. The LIV V strain also seems to be most virulent to rabbits.

  7. Systemic Approach to Virulence Gene Network Analysis for Gaining New Insight into Cryptococcal Virulence

    Directory of Open Access Journals (Sweden)

    Antoni N Malachowski

    2016-10-01

    Full Text Available Cryptococcus neoformans is pathogenic yeast, responsible for highly lethal infections in compromised patients around the globe. C. neoformans typically initiates infections in mammalian lung tissue and subsequently disseminates to the central nervous system where it causes significant pathologies. Virulence genes of C. neoformans are being characterized at an increasing rate, however, we are far from a comprehensive understanding of their roles and genetic interactions. Some of these reported virulence genes are scattered throughout different databases, while others are not yet included. This study gathered and analyzed 150 reported virulence associated factors (VAFs of C. neoformans. Using the web resource STRING database, our study identified different interactions between the total VAFs and those involved specifically in lung and brain infections and identified a new strain specific virulence gene, sho1, involved in the mitogen-activated protein kinase signaling pathway. As predicted by our analysis, sho1 expression enhanced C. neoformans virulence in a mouse model of pulmonary infection, contributing to enhanced non-protective immune Th2 bias and progressively enhancing fungal growth in the infected lungs. Sequence analysis indicated 77.4% (116 of total studied VAFs are soluble proteins, and 22.7% (34 are transmembrane proteins. Motifs involved in regulation and signaling such as protein kinases and transcription factors are highly enriched in Cryptococcus VAFs. Altogether, this study represents a pioneering effort in analysis of the virulence composite network of C. neoformans using a systems biology approach.

  8. Systemic Approach to Virulence Gene Network Analysis for Gaining New Insight into Cryptococcal Virulence.

    Science.gov (United States)

    Malachowski, Antoni N; Yosri, Mohamed; Park, Goun; Bahn, Yong-Sun; He, Yongqun; Olszewski, Michal A

    2016-01-01

    Cryptococcus neoformans is pathogenic yeast, responsible for highly lethal infections in compromised patients around the globe. C. neoformans typically initiates infections in mammalian lung tissue and subsequently disseminates to the central nervous system where it causes significant pathologies. Virulence genes of C. neoformans are being characterized at an increasing rate, however, we are far from a comprehensive understanding of their roles and genetic interactions. Some of these reported virulence genes are scattered throughout different databases, while others are not yet included. This study gathered and analyzed 150 reported virulence associated factors (VAFs) of C. neoformans. Using the web resource STRING database, our study identified different interactions between the total VAFs and those involved specifically in lung and brain infections and identified a new strain specific virulence gene, SHO1, involved in the mitogen-activated protein kinase signaling pathway. As predicted by our analysis, SHO1 expression enhanced C. neoformans virulence in a mouse model of pulmonary infection, contributing to enhanced non-protective immune Th2 bias and progressively enhancing fungal growth in the infected lungs. Sequence analysis indicated 77.4% (116) of total studied VAFs are soluble proteins, and 22.7% (34) are transmembrane proteins. Motifs involved in regulation and signaling such as protein kinases and transcription factors are highly enriched in Cryptococcus VAFs. Altogether, this study represents a pioneering effort in analysis of the virulence composite network of C. neoformans using a systems biology approach.

  9. Bacterial proteases and virulence

    DEFF Research Database (Denmark)

    Frees, Dorte; Brøndsted, Lone; Ingmer, Hanne

    2013-01-01

    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....... 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....

  10. Determinants of Bluetongue Virus Virulence in Murine Models of Disease ▿

    Science.gov (United States)

    Caporale, Marco; Wash, Rachael; Pini, Attilio; Savini, Giovanni; Franchi, Paola; Golder, Matthew; Patterson-Kane, Janet; Mertens, Peter; Di Gialleonardo, Luigina; Armillotta, Gisella; Lelli, Rossella; Kellam, Paul; Palmarini, Massimo

    2011-01-01

    Bluetongue is a major infectious disease of ruminants that is caused by bluetongue virus (BTV). In this study, we analyzed virulence and genetic differences of (i) three BTV field strains from Italy maintained at either a low (L strains) or high (H strains) passage number in cell culture and (ii) three South African “reference” wild-type strains and their corresponding live attenuated vaccine strains. The Italian BTV L strains, in general, were lethal for both newborn NIH-Swiss mice inoculated intracerebrally and adult type I interferon receptor-deficient (IFNAR−/−) mice, while the virulence of the H strains was attenuated significantly in both experimental models. Similarly, the South African vaccine strains were not pathogenic for IFNAR−/− mice, while the corresponding wild-type strains were virulent. Thus, attenuation of the virulence of the BTV strains used in this study is not mediated by the presence of an intact interferon system. No clear distinction in virulence was observed for the South African BTV strains in newborn NIH-Swiss mice. Full genomic sequencing revealed relatively few amino acid substitutions, scattered in several different viral proteins, for the strains found to be attenuated in mice compared to the pathogenic related strains. However, only the genome segments encoding VP1, VP2, and NS2 consistently showed nonsynonymous changes between all virulent and attenuated strain pairs. This study established an experimental platform for investigating the determinants of BTV virulence. Future studies using reverse genetics will allow researchers to precisely map and “weight” the relative influences of the various genome segments and viral proteins on BTV virulence. PMID:21865388

  11. Specific and functional diversity of endophytic bacteria from pine wood nematode Bursaphelenchus xylophilus with different virulence.

    Science.gov (United States)

    Wu, Xiao-Qin; Yuan, Wei-Min; Tian, Xiao-Jing; Fan, Ben; Fang, Xin; Ye, Jian-Ren; Ding, Xiao-Lei

    2013-01-01

    Pine wilt disease (PWD) caused by the pine wood nematode (PWN), Bursaphelenchus xylophilus, is one of the most devastating diseases of Pinus spp. The PWN was therefore listed as one of the most dangerous forest pests in China meriting quarantine. Virulence of the PWN is closely linked with the spread of PWD. However, main factors responsible for the virulence of PWNs are still unclear. Recently epiphytic bacteria carried by PWNs have drawn much attention. But little is known about the relationship between endophytic bacteria and virulence of B. xylophilus. In this research, virulence of ten strains of B. xylophilus from different geographical areas in six provinces of China and four pine species were tested with 2-year-old seedlings of Pinus thunbergii. Endophytic bacteria were isolated from PWNs with different virulence to investigate the relationship between the bacteria and PWN virulence. Meanwhile, the carbon metabolism of endophytic bacteria from highly and low virulent B. xylophilus was analyzed using Biolog plates (ECO). The results indicated that ten strains of PWNs showed a wide range of virulence. Simultaneously, endophytic bacteria were isolated from 90% of the B. xylophilus strains. The dominant endophytic bacteria in the nematodes were identified as species of Stenotrophomonas, Achromobacter, Ewingella, Leifsonia, Rhizobium, and Pseudomonas using molecular and biochemical methods. Moreover, S. maltophilia, and A. xylosoxidans subsp. xylosoxidans were the predominant strains. Most of the strains (80%) from P. massoniana contained either S. maltophilia, A. xylosoxidans, or both species. There was a difference between the abilities of the endophytic bacteria to utilize carbon sources. Endophytic bacteria from highly virulent B. xylophilus had a relatively high utilization rate of carbohydrate and carboxylic acids, while bacteria from low virulent B. xylophilus made better use of amino acids. In conclusion, endophytic bacteria widely exist in B. xylophilus

  12. A comprehensive study on the role of the Yersinia pestis virulence markers in an animal model of pneumonic plague

    NARCIS (Netherlands)

    Kaman, W.E.; Hawkey, S.; Kleij, D. van der; Broekhuijsen, M.P.; Silman, N.J.; Bikker, F.J.

    2011-01-01

    We determined the role of Yersinia pestis virulence markers in an animal model of pneumonic plague. Eleven strains of Y. pestis were characterized using PCR assays to detect the presence of known virulence genes both encoded by the three plasmids as well as chromosomal markers. The virulence of all

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

    Science.gov (United States)

    Pavlickova, Silvie; Dolezalova, Magda; Holko, Ivan

    2015-01-01

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

  14. 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.

  15. Effect of salt and acidic pH on the stability of virulence plasmid (pYV) in Yersinia enterocolitica and expression of virulence-associated characteristics

    Science.gov (United States)

    The stability of the Yersinia enterocolitica virulence plasmid (pYV) under different NaCl concentrations and under acidic pH conditions was investigated. Exposure of five strains representing five serotypes of pYV-bearing virulent Y. enterocolitica to 0.5, 2 and 5% NaCl and under conditions of pH 4...

  16. Metabolism and virulence in Neisseria meningitidis

    Directory of Open Access Journals (Sweden)

    Christoph eSchoen

    2014-08-01

    Full Text Available A longstanding question in infection biology addresses the genetic basis for invasive behaviour in commensal pathogens. A prime example for such a pathogen is Neisseria meningitidis. On the one hand it is a harmless commensal bacterium exquisitely adapted to humans, and on the other hand it sometimes behaves like a ferocious pathogen causing potentially lethal disease such as sepsis and acute bacterial meningitis. Despite the lack of a classical repertoire of virulence genes in N. meningitidis separating commensal from invasive strains, molecular epidemiology suggests that carriage and invasive strains belong to genetically distinct populations. In recent years, it has become increasingly clear that metabolic adaptation enables meningococci to exploit host resources, supporting the concept of nutritional virulence as a crucial determinant of invasive capability. Here, we discuss the contribution of core metabolic pathways in the context of colonization and invasion with special emphasis on results from genome-wide surveys. The metabolism of lactate, the oxidative stress response, and, in particular, glutathione metabolism as well as the denitrification pathway provide examples of how meningococcal metabolism is intimately linked to pathogenesis. We further discuss evidence from genome-wide approaches regarding potential metabolic differences between strains from hyperinvasive and carriage lineages and present new data assessing in vitro growth differences of strains from these two populations. We hypothesize that strains from carriage and hyperinvasive lineages differ in the expression of regulatory genes involved particularly in stress responses and amino acid metabolism under infection conditions.

  17. Secreted Expression of the Cap Gene of Porcine Circovirus Type 2 in Classical Swine Fever Virus C-Strain: Potential of C-Strain Used as a Vaccine Vector

    Directory of Open Access Journals (Sweden)

    Lingkai Zhang

    2017-10-01

    Full Text Available Bivalent vaccines based on live attenuated viruses expressing a heterologous protein are an attractive strategy to address co-infections with various pathogens in the field. Considering the excellent efficacy and safety of the lapinized live attenuated vaccine C-strain (HCLV strain of classical swine fever virus (CSFV, we proposed that C-strain has the potential as a viral vector for developing bivalent vaccines. To this end, we generated three recombinant viruses based on C-strain, one expressing the capsid (Cap gene of porcine circovirus type 2 (PCV2 with the nuclear localization signal (NLS (rHCLV-2ACap, and the other two expressing the PCV2 Cap gene without the NLS yet containing the signal peptide of the prolactin gene (rHCLV-pspCap or that of the ubiquitin-specific peptidase gene (rHCLV-uspCap. All the recombinant viruses exhibited phenotypes similar to those of the parental virus and produced high-level anti-CSFV neutralizing antibodies (NAbs in rabbits. Interestingly, rHCLV-uspCap and rHCLV-pspCap, but not rHCLV-2ACap, elicited detectable anti-Cap and -PCV2 NAbs in rabbits. Taken together, our data demonstrate that C-strain can be used as a viral vector to develop bivalent vaccines.

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

    DEFF Research Database (Denmark)

    Nielsen, A.; Nielsen, Kristian Fog; Frees, D.

    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 ...... of the agr locus are scored based on color change in the presence of a chromogenic beta-galactosidase substrate. The assay can be used to screen for novel antivirulence compounds from many different sources, such as fungi, as demonstrated here.......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...

  19. CRISPR interference can prevent natural transformation and virulence acquisition during in vivo bacterial infection.

    Science.gov (United States)

    Bikard, David; Hatoum-Aslan, Asma; Mucida, Daniel; Marraffini, Luciano A

    2012-08-16

    Pathogenic bacterial strains emerge largely due to transfer of virulence and antimicrobial resistance genes between bacteria, a process known as horizontal gene transfer (HGT). Clustered, regularly interspaced, short palindromic repeat (CRISPR) loci of bacteria and archaea encode a sequence-specific defense mechanism against bacteriophages and constitute a programmable barrier to HGT. However, the impact of CRISPRs on the emergence of virulence is unknown. We programmed the human pathogen Streptococcus pneumoniae with CRISPR sequences that target capsule genes, an essential pneumococcal virulence factor, and show that CRISPR interference can prevent transformation of nonencapsulated, avirulent pneumococci into capsulated, virulent strains during infection in mice. Further, at low frequencies bacteria can lose CRISPR function, acquire capsule genes, and mount a successful infection. These results demonstrate that CRISPR interference can prevent the emergence of virulence in vivo and that strong selective pressure for virulence or antibiotic resistance can lead to CRISPR loss in bacterial pathogens. Copyright © 2012 Elsevier Inc. All rights reserved.

  20. An E2-Substituted Chimeric Pestivirus With DIVA Vaccine Properties

    DEFF Research Database (Denmark)

    Rasmussen, Thomas Bruun; Uttenthal, Åse; Nielsen, Jens

    An advantage of the use of chimeric pestiviruses as modified live vaccines against classical swine fever (CSF) resides in their capacity to be manipulated to achieve the characteristics desired for safe and efficacious DIVA vaccines. We have recently generated a new chimeric virus, Riems26_E2gif...... engineered specifically for this purpose. The E2-substituted Riems26_E2gif was derived by homologues recombination of the complete E2 protein encoding genome region from Border disease strain Gifhorn into a bacterial artificial chromosome (BAC) harbouring the genome of the CSFV vaccine strain C......-Riems. The virulence, immunogenicity and vaccine properties of Riems26_E2gif were tested in a vaccine-challenge experiment in pigs. Riems26_E2gif vaccinated pigs could be differentiated from infected pigs using a CSFV-E2 specific ELISA. Following challenge infection with highly virulent CSFV strain Koslov, all...

  1. Virulence Factors Associated with Enterococcus Faecalis Infective Endocarditis

    DEFF Research Database (Denmark)

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

    2017-01-01

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

  2. Comparative assessment of Vibrio virulence in marine fish larvae

    DEFF Research Database (Denmark)

    Rønneseth, A.; Castillo, D.; D'Alvise, Paul

    2017-01-01

    Vibrionaceae infections are a major obstacle for marine larviculture; however, little is known about virulence differences of Vibrio strains. The virulence of Vibrio strains, mostly isolated from vibriosis outbreaks in farmed fish, was tested in larval challenge trials with cod (Gadus morhua...... effects on survival. Some Vibrio strains were pathogenic in all of the larva species, while some caused disease only in one of the species. Twenty-nine of the Vibrio anguillarum strains increased the mortality of larvae from at least one fish species; however, pathogenicity of the strains differed...... markedly. Other Vibrio species had no or less pronounced effects on larval mortalities. Iron uptake has been related to V. anguillarum virulence; however, the presence or absence of the plasmid pJM1 encoding anguibactin did not correlate with virulence. The genomes of V. anguillarum were compared (D...

  3. High and low-virulent bovine Pasteurella multocida capsular type A isolates exhibit different virulence gene expression patterns in vitro and in vivo.

    Science.gov (United States)

    Li, Nengzhang; Long, Qingshan; Du, Huihui; Zhang, Jixin; Pan, Tingting; Wu, Chenlu; Lei, Guihua; Peng, Yuanyi; Hardwidge, Philip R

    2016-11-30

    Pasteurella multocida capsular type A causes respiratory disease in cattle. P. multocida virulence gene expression patterns, especially among different virulent isolates, during in vitro and in vivo growth are poorly understood. Here we show that the highly virulent bovine P. multocida capsular type A isolate PmCQ2 exhibits a significantly higher growth rate in mice, as compared with a strain of lower virulence, P. multocida capsular type A isolate PmCQ6. Among the six known and potential virulence genes (ompA, ompH, pfhB2, hasR, pm0979, and pm0442) investigated, most genes were expressed more highly in both isolates when grown in vivo as compared with in vitro, with ompH and pm0442 having the highest magnitude of expression. Virulence gene expression was higher in PmCQ6 than in PmCQ2 during in vitro growth. However, in mice, most virulence genes were expressed more highly in PmCQ2 as compared with PmCQ6. Virulence gene expression was highest in the liver and lowest in the lung, but was uncorrelated to bacterial loads. This study indicates that individual pathogenic capacity of P. multocida isolates is associated with the virulence gene expression patterns in vivo growth but not in vitro, and the investigation of virulence gene expression in pathogen should be performed in vivo. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Transient virulence of emerging pathogens.

    Science.gov (United States)

    Bolker, Benjamin M; Nanda, Arjun; Shah, Dharmini

    2010-05-06

    Should emerging pathogens be unusually virulent? If so, why? Existing theories of virulence evolution based on a tradeoff between high transmission rates and long infectious periods imply that epidemic growth conditions will select for higher virulence, possibly leading to a transient peak in virulence near the beginning of an epidemic. This transient selection could lead to high virulence in emerging pathogens. Using a simple model of the epidemiological and evolutionary dynamics of emerging pathogens, along with rough estimates of parameters for pathogens such as severe acute respiratory syndrome, West Nile virus and myxomatosis, we estimated the potential magnitude and timing of such transient virulence peaks. Pathogens that are moderately evolvable, highly transmissible, and highly virulent at equilibrium could briefly double their virulence during an epidemic; thus, epidemic-phase selection could contribute significantly to the virulence of emerging pathogens. In order to further assess the potential significance of this mechanism, we bring together data from the literature for the shapes of tradeoff curves for several pathogens (myxomatosis, HIV, and a parasite of Daphnia) and the level of genetic variation for virulence for one (myxomatosis). We discuss the need for better data on tradeoff curves and genetic variance in order to evaluate the plausibility of various scenarios of virulence evolution.

  5. Correlates of virulence in a frog-killing fungal pathogen: evidence from a California amphibian decline

    Science.gov (United States)

    Jonah Piovia-Scott; Karen Pope; S. Joy Worth; Erica Bree Rosenblum; Dean Simon; Gordon Warburton; Louise A. Rollins-Smith; Laura K. Reinert; Heather L. Wells; Dan Rejmanek; Sharon Lawler; Janet Foley

    2015-01-01

    The fungal pathogen Batrachochytrium dendrobatidis (Bd) has caused declines and extinctions in amphibians worldwide, and there is increasing evidence that some strains of this pathogen are more virulent than others. While a number of putative virulence factors have been identified, few studies link these factors to specific epizootic events. We...

  6. 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 ...

  7. Proteomic comparison of phase I and II coxiella burnetii cells reveals potential virulence biomarkers

    Science.gov (United States)

    Coxiella burnetii, a category B biological warfare agent, causes several worldwide outbreaks of zoonotic disease each year. In order to identify C. burnetii virulence factors, the virulent phase I and avirulent phase II variants of the Nine Mile RSA strains, were propagated in embryonated hen eggs ...

  8. Evaluation of a FRET-peptide substrate to predict virulence in Pseudomonas aeruginosa

    NARCIS (Netherlands)

    W.E. Kaman (Wendy); N. El Arkoubi-El Arkoubi (Nora); S. Roffel (Sanne); H.P. Endtz (Hubert); A.F. van Belkum (Alex); F.J. Bikker (Floris); J.P. Hays (John)

    2013-01-01

    textabstractPseudomonas aeruginosa produces a number of proteases that are associated with virulence and disease progression. A substrate able to detect P. aeruginosa-specific proteolytic activity could help to rapidly alert clinicians to the virulence potential of individual P. aeruginosa strains.

  9. Evaluation of a FRET-peptide substrate to predict virulence in Pseudomonas aeruginosa

    NARCIS (Netherlands)

    Kaman, W.E.; El Arkoubi-El Arkoubi, N.; Roffel, S.; Endtz, H.P.; van Belkum, A.; Bikker, F.J.; Hays, J.P.

    2013-01-01

    Pseudomonas aeruginosa produces a number of proteases that are associated with virulence and disease progression. A substrate able to detect P. aeruginosa-specific proteolytic activity could help to rapidly alert clinicians to the virulence potential of individual P. aeruginosa strains. For this

  10. Variable Virulence of Biotype 3 Vibrio vulnificus due to MARTX Toxin Effector Domain Composition.

    Science.gov (United States)

    Kim, Byoung Sik; Gavin, Hannah E; Satchell, Karla J F

    2017-01-01

    Vibrio vulnificus is an environmental organism that causes septic human infections characterized by high morbidity and mortality. The annual incidence and global distribution of this pathogen are increasing as ocean waters warm. Clinical strains exhibit variations in the primary virulence toxin, suggesting a potential for the emergence of new strains with altered virulence properties. A clonal outbreak of tilapia-associated wound infections in Israel serves as a natural experiment for the sudden emergence of a new V. vulnificus strain. The effector domain content of the multifunctional autoprocessing RTX (MARTX) toxin of the outbreak-associated biotype 3 (BT3) strains was previously shown to harbor a modification generated by recombination. The modification introduced an actin-induced adenylate cyclase effector domain (ExoY) and an effector domain that disrupts the Golgi organelle (DmX). Here, we report that the exchange of these effector domains for a putative progenitor biotype 1 toxin arrangement produces a toxin that slows the lysis kinetics of targeted epithelial cells but increases cellular rounding phenotypes in response to bacteria. In addition, replacing the biotype 3 toxin variant with the putative progenitor biotype 1 variant renders the resulting strain significantly more virulent in mice. This suggests that the exchange of MARTX effector domains during the emergence of BT3 generated a toxin with reduced toxin potency, resulting in decreased virulence of this outbreak-associated strain. We posit that selection for reduced virulence may serve as a route for this lethal infectious agent to enter the human food chain by allowing it to persist in natural hosts. IMPORTANCEVibrio vulnificus is a serious infection linked to climate change. The virulence capacity of these bacteria can vary by gene exchange, resulting in new variants of the primary virulence toxin. In this study, we tested whether the emergence of an epidemic strain of V. vulnificus with a

  11. Toxigenic Helicobacter pylori infection precedes gastric hypochlorhydria in cancer relatives, and H. pylori virulence evolves in these families.

    Science.gov (United States)

    Argent, Richard H; Thomas, Rachael J; Aviles-Jimenez, Francisco; Letley, Darren P; Limb, Marie C; El-Omar, Emad M; Atherton, John C

    2008-04-01

    Helicobacter pylori infection by virulent strains is associated with gastric adenocarcinoma. We aimed to determine whether infection with virulent H. pylori preceded precancerous gastric hypochlorhydria and atrophy in gastric cancer relatives and quantify the extent of virulence factor evolution. H. pylori strains from 51 Scottish gastric cancer relatives were characterized by genetic fingerprinting and typing the vacuolating cytotoxin gene (vacA), the cytotoxin-associated gene (cagA), and housekeeping genes. We phenotyped strains by coculture with gastric epithelial cells and assessing vacuolation (microscopy), CagA tyrosine phosphorylation (immunoblot), and interleukin-8 secretion (ELISA). Toxigenic (vacA type s1/m1) H. pylori was associated with precancerous gastric hypochlorhydria (Phypochlorhydria, suggesting that virulent H. pylori increases cancer risk by causing this condition. Microevolution of virulence genes is common within families of gastric cancer patients and changes H. pylori virulence.

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

    NARCIS (Netherlands)

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

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

  13. Evaluation of iron dextran and mucin for enhancement of the virulence of Yersinia enterocolitica serotype O:3 in mice.

    OpenAIRE

    Smith, R. E.; Carey, A M; Damare, J M; Hetrick, F M; Johnston, R W; Lee, W.H.

    1981-01-01

    The pathogenic role of Yersinia enterocolitica serotypes O:3, O:8, and O:9 in human infections is well documented. Whereas the virulence of the O:8 strains can be readily demonstrated in mice by 50% lethal dose determinations, the O:3 and O:9 strains have no lethal effect on mice by any route of inoculation. A mouse virulence test for the O:3 and O:9 strains is described. Y. enterocolitica strains were first tested for the presence of virulence-associated plasmid characteristics by auto-agglu...

  14. Virulence potential and genomic mapping of the worldwide clone Escherichia coli ST131.

    Directory of Open Access Journals (Sweden)

    Jean-Philippe Lavigne

    Full Text Available Recently, the worldwide propagation of clonal CTX-M-15-producing Escherichia coli isolates, namely ST131 and O25b:H4, has been reported. Like the majority of extra-intestinal pathogenic E. coli isolates, the pandemic clone ST131 belongs to phylogenetic group B2, and has recently been shown to be highly virulent in a mouse model, even though it lacks several genes encoding key virulence factors (Pap, Cnf1 and HlyA. Using two animal models, Caenorhabditis elegans and zebrafish embryos, we assessed the virulence of three E. coli ST131 strains (2 CTX-M-15- producing urine and 1 non-ESBL-producing faecal isolate, comparing them with five non-ST131 B2 and a group A uropathogenic E. coli (UPEC. In C. elegans, the three ST131 strains showed intermediate virulence between the non virulent group A isolate and the virulent non-ST131 B2 strains. In zebrafish, the CTX-M-15-producing ST131 UPEC isolates were also less virulent than the non-ST131 B2 strains, suggesting that the production of CTX-M-15 is not correlated with enhanced virulence. Amongst the non-ST131 B2 group isolates, variation in pathogenic potential in zebrafish embryos was observed ranging from intermediate to highly virulent. Interestingly, the ST131 strains were equally persistent in surviving embryos as the non-ST131-group B2 strains, suggesting similar mechanisms may account for development of persistent infection. Optical maps of the genome of the ST131 strains were compared with those of 24 reference E. coli strains. Although small differences were seen within the ST131 strains, the tree built on the optical maps showed that these strains belonged to a specific cluster (86% similarity with only 45% similarity with the other group B2 strains and 25% with strains of group A and D. Thus, the ST131 clone has a genetic composition that differs from other group B2 strains, and appears to be less virulent than previously suspected.

  15. Hairy root: plasmid encodes virulence traits in Agrobacterium rhizogenes.

    Science.gov (United States)

    White, F F; Nester, E W

    1980-01-01

    Agrobacterium rhizogenes strain 15834, which incites hairy root disease in plants, harbors three large plasmids: pAr15834a (107 x 10(6) daltons), pAr15834b (154 x 10(6) daltons), and pAr15834c (258 x 10(6) daltons). Kanamycin-resistant transconjugants were selected in a cross of kanamycin-resistant derivate of strain 15834 and an avirulent recipient. The transconjugants belonging to one class were virulent and contained all three donor plasmids. These transconjugants also acquired sensitivity to the bacteriocin agrocin 84. The loss of plasmids from virulent transconjugants during growth at 37 degrees C indicated that virulence genes reside on pAr15834b, whereas agrocin 84 sensitivity genes reside on pAr15834a. The pathology induced by the virulent transconjugants containing only pAr15834b was identical to that produced by the wild-type strain of A. rhizogenes. Restriction endonuclease fragment analysis of plasmids from the transconjugants and the donor revealed that pAr15834c is a cointegrate of pAr15834a and pAr15834b. Kanamycin-resistant transconjugants belonging to a second class were avirulent and contained an altered form of pAr15834b. Strain 15834 can utilize octopine. However, this trait was not detected in any of the transconjugants. Octopine is not synthesized by infected plant tissue. Images PMID:6245060

  16. Virulence markers of opportunistic black yeast in Exophiala

    NARCIS (Netherlands)

    Sav, Hafize; Ozakkas, Fatma; Altınbas, Rabiye; Kiraz, Nuri; Tümgör, Ayşegül; Gümral, Ramazan; Döğen, Aylin; Ilkit, Macit; de Hoog, G Sybren

    The black yeast genus Exophiala is known to cause a wide variety of diseases in severely ill individuals but can also affect immunocompetent individuals. Virulence markers and other physiological parameters were tested in eight clinical and 218 environmental strains, with a specific focus on

  17. Pseudomonas aeruginosa virulence analyzed in a Dictyostelium discoideum host system.

    Science.gov (United States)

    Cosson, Pierre; Zulianello, Laurence; Join-Lambert, Olivier; Faurisson, François; Gebbie, Leigh; Benghezal, Mohammed; Van Delden, Christian; Curty, Lasta Kocjancic; Köhler, Thilo

    2002-06-01

    Pseudomonas aeruginosa is an important opportunistic pathogen that produces a variety of cell-associated and secreted virulence factors. P. aeruginosa infections are difficult to treat effectively because of the rapid emergence of antibiotic-resistant strains. In this study, we analyzed whether the amoeba Dictyostelium discoideum can be used as a simple model system to analyze the virulence of P. aeruginosa strains. The virulent wild-type strain PAO1 was shown to inhibit growth of D. discoideum. Isogenic mutants deficient in the las quorum-sensing system were almost as inhibitory as the wild type, while rhl quorum-sensing mutants permitted growth of Dictyostelium cells. Therefore, in this model system, factors controlled by the rhl quorum-sensing system were found to play a central role. Among these, rhamnolipids secreted by the wild-type strain PAO1 could induce fast lysis of D. discoideum cells. By using this simple model system, we predicted that certain antibiotic-resistant mutants of P. aeruginosa should show reduced virulence. This result was confirmed in a rat model of acute pneumonia. Thus, D. discoideum could be used as a simple nonmammalian host system to assess pathogenicity of P. aeruginosa.

  18. Virulence of Burkholderia mallei quorum-sensing mutants.

    Science.gov (United States)

    Majerczyk, Charlotte; Kinman, Loren; Han, Tony; Bunt, Richard; Greenberg, E Peter

    2013-05-01

    Many Proteobacteria use acyl-homoserine lactone-mediated quorum-sensing (QS) to activate specific sets of genes as a function of cell density. QS often controls the virulence of pathogenic species, and in fact a previous study indicated that QS was important for Burkholderia mallei mouse lung infections. To gain in-depth information on the role of QS in B. mallei virulence, we constructed and characterized a mutant of B. mallei strain GB8 that was unable to make acyl-homoserine lactones. The QS mutant showed virulence equal to that of its wild-type parent in an aerosol mouse infection model, and growth in macrophages was indistinguishable from that of the parent strain. Furthermore, we assessed the role of QS in B. mallei ATCC 23344 by constructing and characterizing a mutant strain producing AiiA, a lactonase enzyme that degrades acyl-homoserine lactones. Although acyl-homoserine lactone levels in cultures of this strain are very low, it showed full virulence. Contrary to the previous report, we conclude that QS is not required for acute B. mallei infections of mice. QS may be involved in some stage of chronic infections in the natural host of horses, or the QS genes may be remnants of the QS network in B. pseudomallei from which this host-adapted pathogen evolved.

  19. Metal acquisition and virulence in Brucella

    Science.gov (United States)

    Roop, R. Martin

    2013-01-01

    Similar to other bacteria, Brucella strains require several biologically essential metals for their survival in vitro and in vivo. Acquiring sufficient levels of some of these metals, particularly iron, manganese and zinc, is especially challenging in the mammalian host, where sequestration of these micronutrients is a well-documented component of both the innate and acquired immune responses. This review describes the Brucella metal transporters that have been shown to play critical roles in the virulence of these bacteria in experimental and natural hosts. PMID:22632611

  20. Transmission of classical swine fever virus depends on the clinical course of infection which is associated with high and low level of virus excretion

    NARCIS (Netherlands)

    Weesendorp, E.; Backer, J.A.; Stegeman, J.A.; Loeffen, W.L.A.

    2011-01-01

    Infection with moderately virulent strains of classical swine fever virus (CSFV) can lead to different courses of disease: either (sub)acute, resulting in death or recovery, or chronic disease. The virus excretion dynamics between these courses are quite dissimilar, but it is not known if this also

  1. Co-expression of the C-terminal domain of Yersinia enterocolitica ...

    Indian Academy of Sciences (India)

    2015-01-11

    Jan 11, 2015 ... infection and persistent infection), which causes great eco- nomic losses to livestock (Moennig 2000). ... targeting delivery of antigen to the lymphatic tissues (Clark et al. 1998). This characteristic is used to ... kidney cell line PK-15. The virulent CSFV. 'Shimen' strain was provided by the Control Institute of.

  2. 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.

  3. Virulence Characterization of Salmonella enterica by a New Microarray: Detection and Evaluation of the Cytolethal Distending Toxin Gene Activity in the Unusual Host S. Typhimurium

    OpenAIRE

    Rui Figueiredo; Roderick Card; Carla Nunes; Manal AbuOun; Bagnall, Mary C.; Javier Nunez; Nuno Mendonça; Anjum, Muna F.; Gabriela Jorge da Silva

    2015-01-01

    Salmonella enterica is a zoonotic foodborne pathogen that causes acute gastroenteritis in humans. We assessed the virulence potential of one-hundred and six Salmonella strains isolated from food animals and products. A high through-put virulence genes microarray demonstrated Salmonella Pathogenicity Islands (SPI) and adherence genes were highly conserved, while prophages and virulence plasmid genes were variably present. Isolates were grouped by serotype, and virulence plasmids separated S. T...

  4. Investigating the ?Trojan Horse? Mechanism of Yersinia pestis Virulence

    Energy Technology Data Exchange (ETDEWEB)

    McCutchen-Maloney, S L; Fitch, J P

    2005-02-08

    Yersinia pestis, the etiological agent of plague, is a Gram-negative, highly communicable, enteric bacterium that has been responsible for three historic plague pandemics. Currently, several thousand cases of plague are reported worldwide annually, and Y. pestis remains a considerable threat from a biodefense perspective. Y. pestis infection can manifest in three forms: bubonic, septicemic, and pneumonic plague. Of these three forms, pneumonic plague has the highest fatality rate ({approx}100% if left untreated), the shortest intervention time ({approx}24 hours), and is highly contagious. Currently, there are no rapid, widely available vaccines for plague and though plague may be treated with antibiotics, the emergence of both naturally occurring and potentially engineered antibiotic resistant strains makes the search for more effective therapies and vaccines for plague of pressing concern. The virulence mechanism of this deadly bacterium involves induction of a Type III secretion system, a syringe-like apparatus that facilitates the injection of virulence factors, termed Yersinia outer membrane proteins (Yops), into the host cell. These virulence factors inhibit phagocytosis and cytokine secretion, and trigger apoptosis of the host cell. Y. pestis virulence factors and the Type III secretion system are induced thermally, when the bacterium enters the mammalian host from the flea vector, and through host cell contact (or conditions of low Ca{sup 2+} in vitro). Apart from the temperature increase from 26 C to 37 C and host cell contact (or low Ca{sup 2+} conditions), other molecular mechanisms that influence virulence induction in Y. pestis are largely uncharacterized. This project focused on characterizing two novel mechanisms that regulate virulence factor induction in Y. pestis, immunoglobulin G (IgG) binding and quorum sensing, using a real-time reporter system to monitor induction of virulence. Incorporating a better understanding of the mechanisms of virulence

  5. Brucella, nitrogen and virulence.

    Science.gov (United States)

    Ronneau, Severin; Moussa, Simon; Barbier, Thibault; Conde-Álvarez, Raquel; Zuniga-Ripa, Amaia; Moriyon, Ignacio; Letesson, Jean-Jacques

    2016-08-01

    The brucellae are α-Proteobacteria causing brucellosis, an important zoonosis. Although multiplying in endoplasmic reticulum-derived vacuoles, they cause no cell death, suggesting subtle but efficient use of host resources. Brucellae are amino-acid prototrophs able to grow with ammonium or use glutamate as the sole carbon-nitrogen source in vitro. They contain more than twice amino acid/peptide/polyamine uptake genes than the amino-acid auxotroph Legionella pneumophila, which multiplies in a similar vacuole, suggesting a different nutritional strategy. During these two last decades, many mutants of key actors in nitrogen metabolism (transporters, enzymes, regulators, etc.) have been described to be essential for full virulence of brucellae. Here, we review the genomic and experimental data on Brucella nitrogen metabolism and its connection with virulence. An analysis of various aspects of this metabolism (transport, assimilation, biosynthesis, catabolism, respiration and regulation) has highlighted differences and similarities in nitrogen metabolism with other α-Proteobacteria. Together, these data suggest that, during their intracellular life cycle, the brucellae use various nitrogen sources for biosynthesis, catabolism and respiration following a strategy that requires prototrophy and a tight regulation of nitrogen use.

  6. The Early Dendritic Cell Signaling Induced by Virulent Francisella tularensis Strain Occurs in Phases and Involves the Activation of Extracellular Signal-Regulated Kinases (ERKs) and p38 In the Later Stage

    Czech Academy of Sciences Publication Activity Database

    Fabrik, I.; Link, M.; Putzova, D.; Plzakova, L.; Lubovska, Zuzana; Philimonenko, Vlada; Pavkova, I.; Řehulka, P.; Krocová, Z.; Hozák, Pavel; Santic, M.; Stulík, J.

    2018-01-01

    Roč. 17, č. 1 (2018), s. 95-108 ISSN 1535-9476 R&D Projects: GA MŠk(CZ) LM2015062 Institutional support: RVO:68378050 Keywords : factor-alpha production * live vaccine strain * phosphorylation sites * negative regulator * innate immunity * lvs infection * pathway * identification * reveals * mapk Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 6.540, year: 2016

  7. Diet, microbial virulence, and Helicobacter pylori-induced gastric cancer.

    Science.gov (United States)

    Cover, Timothy L; Peek, Richard M

    2013-01-01

    Gastric adenocarcinoma is a leading cause of cancer-related death worldwide, and Helicobacter pylori infection is one of the strongest known risk factors for this malignancy. H. pylori strains exhibit a high level of genetic diversity, and the risk of gastric cancer is higher in persons carrying certain strain types (for example, those that contain a cag pathogenicity island or type s1 vacA alleles) than in persons carrying other strain types. Additional risk factors for gastric cancer include specific human genetic polymorphisms and specific dietary preferences (for example, a high-salt diet or a diet deficient in fruits and vegetables). Finally, iron-deficiency anemia is a risk factor for gastric cancer. Recent studies have provided evidence that several dietary risk factors for gastric cancer directly impact H. pylori virulence. In this review article, we discuss mechanisms by which diet can modulate H. pylori virulence and thereby influence gastric cancer risk.

  8. Intensive fish farming and the evolution of pathogen virulence: the case of columnaris disease in Finland.

    Science.gov (United States)

    Pulkkinen, K; Suomalainen, L-R; Read, A F; Ebert, D; Rintamäki, P; Valtonen, E T

    2010-02-22

    Ecological changes affect pathogen epidemiology and evolution and may trigger the emergence of novel diseases. Aquaculture radically alters the ecology of fish and their pathogens. Here we show an increase in the occurrence of the bacterial fish disease Flavobacterium columnare in salmon fingerlings at a fish farm in northern Finland over 23 years. We hypothesize that this emergence was owing to evolutionary changes in bacterial virulence. We base this argument on several observations. First, the emergence was associated with increased severity of symptoms. Second, F. columnare strains vary in virulence, with more lethal strains inducing more severe symptoms prior to death. Third, more virulent strains have greater infectivity, higher tissue-degrading capacity and higher growth rates. Fourth, pathogen strains co-occur, so that strains compete. Fifth, F. columnare can transmit efficiently from dead fish, and maintain infectivity in sterilized water for months, strongly reducing the fitness cost of host death likely experienced by the pathogen in nature. Moreover, this saprophytic infectiousness means that chemotherapy strongly select for strains that rapidly kill their hosts: dead fish remain infectious; treated fish do not. Finally, high stocking densities of homogeneous subsets of fish greatly enhance transmission opportunities. We suggest that fish farms provide an environment that promotes the circulation of more virulent strains of F. columnare. This effect is intensified by the recent increases in summer water temperature. More generally, we predict that intensive fish farming will lead to the evolution of more virulent pathogens.

  9. Genotypic and Phenotypic Diversity of Cryptococcus gattii VGII Clinical Isolates and Its Impact on Virulence

    Directory of Open Access Journals (Sweden)

    Vanessa A. Barcellos

    2018-02-01

    Full Text Available The Cryptococcus gattii species complex harbors the main etiological agents of cryptococcosis in immunocompetent patients. C. gattii molecular type VGII predominates in the north and northeastern regions of Brazil, leading to high morbidity and mortality rates. C. gattii VGII isolates have a strong clinical relevance and phenotypic variations. These phenotypic variations among C. gattii species complex isolates suggest that some strains are more virulent than others, but little information is available related to the pathogenic properties of those strains. In this study, we analyzed some virulence determinants of C. gattii VGII strains (CG01, CG02, and CG03 isolated from patients in the state of Piauí, Brazil. The C. gattii R265 VGIIa strain, which was isolated from the Vancouver outbreak, differed from C. gattii CG01, CG02 and CG03 isolates (also classified as VGII when analyzed the capsular dimensions, melanin production, urease activity, as well as the glucuronoxylomannan (GXM secretion. Those differences directly reflected in their virulence potential. In addition, CG02 displayed higher virulence compared to R265 (VGIIa strain in a cryptococcal murine model of infection. Lastly, we examined the genotypic diversity of these strains through Multilocus Sequence Type (MLST and one new subtype was described for the CG02 isolate. This study confirms the presence and the phenotypic and genotypic diversity of highly virulent strains in the Northeast region of Brazil.

  10. Assessing the diversity of the virulence potential of Escherichia coli isolated from bacteremia in São Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    A.C.M. Santos

    2013-11-01

    Full Text Available Most of the knowledge of the virulence determinants of extraintestinal pathogenic Escherichia coli (ExPEC comes from studies with human strains causing urinary tract infections and neonatal meningitis and animal strains causing avian colibacillosis. In this research, we analyzed the phylogenetic background, the presence of 20 ExPEC virulence factors, and the intrinsic virulence potential of 74 E. coli strains isolated in São Paulo, Brazil, from 74 hospitalized patients (43 males and 31 females with unknown-source bacteremia. Unlike other places in the world, the bacteremic strains originated equally from phylogroups B2 (35% and D (30%. A great variability in the profiles of virulence factors was noted in this survey. Nevertheless, 61% of the strains were classified as ExPEC, meaning that they possessed intrinsic virulent potential. Accordingly, these strains presented high virulence factor scores (average of 8.7, and were positively associated with 12 of 17 virulence factors detected. On the contrary, the non-ExPEC strains, isolated from 39% of the patients, presented a generally low virulence capacity (medium virulence factor score of 3.1, and were positively associated with only the colicin cvaC gene. These results show the importance of discriminating E. coli isolates that possess characteristics of true pathogens from those that may be merely opportunistic in order to better understand the virulence mechanisms involved in extraintestinal E. coli infections. Such knowledge is essential for epidemiological purposes as well as for development of control measures aimed to minimize the incidence of these life-threatening and costly infections.

  11. Virulence differences among Francisella tularensis subsp. tularensis clades in mice.

    Directory of Open Access Journals (Sweden)

    Claudia R Molins

    Full Text Available Francisella tularensis subspecies tularensis (type A and holarctica (type B are of clinical importance in causing tularemia. Molecular typing methods have further separated type A strains into three genetically distinct clades, A1a, A1b and A2. Epidemiological analyses of human infections in the United States suggest that A1b infections are associated with a significantly higher mortality rate as compared to infections caused by A1a, A2 and type B. To determine if genetic differences as defined by molecular typing directly correlate with differences in virulence, A1a, A1b, A2 and type B strains were compared in C57BL/6 mice. Here we demonstrate significant differences between survival curves for infections caused by A1b versus A1a, A2 and type B, with A1b infected mice dying earlier than mice infected with A1a, A2 or type B; these results were conserved among multiple strains. Differences were also detected among type A clades as well as between type A clades and type B with respect to bacterial burdens, and gross anatomy in infected mice. Our results indicate that clades defined within F. tularensis subsp. tularensis by molecular typing methods correlate with virulence differences, with A1b strains more virulent than A1a, A2 and type B strains. These findings indicate type A strains are not equivalent with respect to virulence and have important implications for public health as well as basic research programs.

  12. Multiple genome segments determine virulence of bluetongue virus serotype 8.

    Science.gov (United States)

    Janowicz, Anna; Caporale, Marco; Shaw, Andrew; Gulletta, Salvatore; Di Gialleonardo, Luigina; Ratinier, Maxime; Palmarini, Massimo

    2015-05-01

    Bluetongue virus (BTV) causes bluetongue, a major hemorrhagic disease of ruminants. In order to investigate the molecular determinants of BTV virulence, we used a BTV8 strain minimally passaged in tissue culture (termed BTV8L in this study) and a derivative strain passaged extensively in tissue culture (BTV8H) in in vitro and in vivo studies. BTV8L was pathogenic in both IFNAR(-/-) mice and in sheep, while BTV8H was attenuated in both species. To identify genetic changes which led to BTV8H attenuation, we generated 34 reassortants between BTV8L and BTV8H. We found that partial attenuation of BTV8L in IFNAR(-/-) mice was achieved by simply replacing genomic segment 2 (Seg2, encoding VP2) or Seg10 (encoding NS3) with the BTV8H homologous segments. Fully attenuated viruses required at least two genome segments from BTV8H, including Seg2 with either Seg1 (encoding VP1), Seg6 (encoding VP6 and NS4), or Seg10 (encoding NS3). Conversely, full reversion of virulence of BTV8H required at least five genomic segments of BTV8L. We also demonstrated that BTV8H acquired an increased affinity for glycosaminoglycan receptors during passaging in cell culture due to mutations in its VP2 protein. Replication of BTV8H was relatively poor in interferon (IFN)-competent primary ovine endothelial cells compared to replication of BTV8L, and this phenotype was determined by several viral genomic segments, including Seg4 and Seg9. This study demonstrated that multiple viral proteins contribute to BTV8 virulence. VP2 and NS3 are primary determinants of BTV pathogenesis, but VP1, VP5, VP4, VP6, and VP7 also contribute to virulence. Bluetongue is one of the major infectious diseases of ruminants, and it is listed as a notifiable disease by the World Organization for Animal Health (OIE). The clinical outcome of BTV infection varies considerably and depends on environmental and host- and virus-specific factors. Over the years, BTV serotypes/strains with various degrees of virulence (including

  13. Assessment of Listeria monocytogenes virulence in the Galleria mellonella insect larvae model.

    Science.gov (United States)

    Rakic Martinez, Mira; Wiedmann, Martin; Ferguson, Martine; Datta, Atin R

    2017-01-01

    Several animal models have been used to understand the molecular basis of the pathogenicity, infectious dose and strain to strain variation of Listeria monocytogenes. The greater wax worm Galleria mellonella, as an alternative model, provides some useful advantages not available with other models and has already been described as suitable for the virulence assessment of various pathogens including L. monocytogenes. The objectives of this study are: 1) confirming the usefulness of this model with a wide panel of Listeria spp. including non-pathogenic L. innocua, L. seeligeri, L. welshimeri and animal pathogen L. ivanovii; 2) assessment of virulence of several isogenic in-frame deletion mutants in virulence and stress related genes of L. monocytogenes and 3) virulence assessment of paired food and clinical isolates of L. monocytogenes from 14 major listeriosis outbreaks occurred worldwide between 1980 and 2015. Larvae injected with different concentrations of Listeria were incubated at 37°C and monitored over seven days for time needed to kill 50% of larvae (LT50) and to determine change of bacterial population in G. mellonella, 2 and 24 hours post-inoculation. Non-pathogenic members of Listeria and L. ivanovii showed significantly (P < 0.05) higher LT50 (lower virulence) than the wild type L. monocytogenes strains. Isogenic mutants of L. monocytogenes with the deletions in prfA, plcA, hly, actA and virR genes, also showed significantly (P < 0.05) higher LT50 than the wild type strain at the inoculum of 106CFU/larva. Food isolates had significantly (P < 0.05) lower virulence than the paired clinical isolates, at all three inoculum concentrations. L. monocytogenes strains related to non-invasive (gastroenteritis) outbreaks of listeriosis showed significantly (P < 0.05) lower virulence than isolates of the same serotype obtained from outbreaks with invasive symptoms. The difference, however, was dose and strain- dependent. No significant differences in virulence were

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

    Science.gov (United States)

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

    2017-03-01

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

  15. Divergence between the Highly Virulent Zoonotic Pathogen Helicobacter heilmannii and Its Closest Relative, the Low-Virulence “Helicobacter ailurogastricus” sp. nov.

    Science.gov (United States)

    Joosten, Myrthe; Lindén, Sara; Rossi, Mirko; Skoog, Emma; Padra, Médea; Peters, Fanny; Perkins, Tim; Vandamme, Peter; Van Nieuwerburgh, Filip; D'Herde, Katharina; Van den Broeck, Wim; Flahou, Bram; Deforce, Dieter; Ducatelle, Richard; Marshall, Barry; Haesebrouck, Freddy

    2015-01-01

    Helicobacter heilmannii naturally colonizes the stomachs of dogs and cats and has been associated with gastric disorders in humans. Nine feline Helicobacter strains, classified as H. heilmannii based on ureAB and 16S rRNA gene sequences, were divided into a highly virulent and a low-virulence group. The genomes of these strains were sequenced to investigate their phylogenetic relationships, to define their gene content and diversity, and to determine if the differences in pathogenicity were associated with the presence or absence of potential virulence genes. The capacities of these helicobacters to bind to the gastric mucosa were investigated as well. Our analyses revealed that the low-virulence strains do not belong to the species H. heilmannii but to a novel, closely related species for which we propose the name Helicobacter ailurogastricus. Several homologs of H. pylori virulence factors, such as IceA1, HrgA, and jhp0562-like glycosyltransferase, are present in H. heilmannii but absent in H. ailurogastricus. Both species contain a VacA-like autotransporter, for which the passenger domain is remarkably larger in H. ailurogastricus than in H. heilmannii. In addition, H. ailurogastricus shows clear differences in binding to the gastric mucosa compared to H. heilmannii. These findings highlight the low-virulence character of this novel Helicobacter species. PMID:26527212

  16. Molecular analysis of virulent determinants of enterovirus 71.

    Directory of Open Access Journals (Sweden)

    Renqing Li

    Full Text Available Enterovirus 71 (EV71 is the most important causative agent of hand, foot and mouth disease (HFMD in children. In most cases, it is a self-limiting illness. However some EV71 infectious cases can develop severe clinical outcomes, such as encephalitis, meningitis, poliomyelitis like paralysis, and even death. To identify the determinants of virulence, the deduced amino acid sequence of polyprotein and nucleotide sequence of 5'-NTR and 3'-NTR in 25 SC-EV71 strains (strains from severe cases and 31 MC-EV71 strains (strains from mild cases were analyzed. Results showed four amino acids on two positions (Gly(P710/Gln(P710/Arg(P710 and Glu(P729 on the DE and EF loop of VP1, one (Lys(P930 on the surface of protease 2A and four nucleotides on three positions (G(P272, U(P488 and A(P700/U(P700 in the 5'-NTR region are associated with EV71 virulent phenotype. Predicted secondary structure of RNA using the consensus sequence of 5'-NTR by RNAStructure showed the mutation of nucleotide at position 488 in strain BJ08-Z004-3 (position 491 in prototype strain BrCr can result in the discrepancy of an additional pair of nucleotides and thus change the stability of the second structure of IRES. Fragment base content analysis showed that in the region 696 to 714 bp at the 5'-NTR, where the A(P700/U(P700 was located, the nucleotide constitution ratios differed significantly between SC-EV71 and MC-EV71 strains. In conclusion, comparative genomic analysis showed that virulence of EV71 strains are mainly determined by the amino acids on two positions of VP1, one position of protease 2A and the nucleotides on three positions in 5'-NTR.

  17. Differences in Virulence of Marine and Freshwater Isolates of Viral Hemorrhagic Septicemia Virus In Vivo Correlate with In Vitro Ability To Infect Gill Epithelial Cells and Macrophages of Rainbow Trout (Oncorhynchus mykiss)

    DEFF Research Database (Denmark)

    Brudeseth, Bjørn E.; Skall, Helle Frank; Evensen, Øystein

    2008-01-01

    ). The strains included one low-virulence marine VHSV (ma-VHSV) strain, ma-1p8, and a highly pathogenic freshwater VHSV (fw-VHSV) strain, fw-DK-3592B. Infectivities toward trout head kidney macrophages were also studied (by a time course method), and differences in in vivo virulence were reconfirmed, the aim...

  18. Genetic Modulation of c-di-GMP Turnover Affects Multiple Virulence Traits and Bacterial Virulence in Rice Pathogen Dickeya zeae.

    Directory of Open Access Journals (Sweden)

    Yufan Chen

    Full Text Available The frequent outbreaks of rice foot rot disease caused by Dickeya zeae have become a significant concern in rice planting regions and countries, but the regulatory mechanisms that govern the virulence of this important pathogen remain vague. Given that the second messenger cyclic di-GMP (c-di-GMP is associated with modulation of various virulence-related traits in various microorganisms, here we set to investigate the role of the genes encoding c-di-GMP metabolism in the regulation of the bacterial physiology and virulence by construction all in-frame deletion mutants targeting the annotated c-di-GMP turnover genes in D. zeae strain EC1. Phenotype analyses identified individual mutants showing altered production of exoenzymes and phytotoxins, biofilm formation and bacterial motilities. The results provide useful clues and a valuable toolkit for further characterization and dissection of the regulatory complex that modulates the pathogenesis and persistence of this important bacterial pathogen.

  19. Genetic Modulation of c-di-GMP Turnover Affects Multiple Virulence Traits and Bacterial Virulence in Rice Pathogen Dickeya zeae.

    Science.gov (United States)

    Chen, Yufan; Lv, Mingfa; Liao, Lisheng; Gu, Yanfang; Liang, Zhibin; Shi, Zurong; Liu, Shiyin; Zhou, Jianuan; Zhang, Lianhui

    2016-01-01

    The frequent outbreaks of rice foot rot disease caused by Dickeya zeae have become a significant concern in rice planting regions and countries, but the regulatory mechanisms that govern the virulence of this important pathogen remain vague. Given that the second messenger cyclic di-GMP (c-di-GMP) is associated with modulation of various virulence-related traits in various microorganisms, here we set to investigate the role of the genes encoding c-di-GMP metabolism in the regulation of the bacterial physiology and virulence by construction all in-frame deletion mutants targeting the annotated c-di-GMP turnover genes in D. zeae strain EC1. Phenotype analyses identified individual mutants showing altered production of exoenzymes and phytotoxins, biofilm formation and bacterial motilities. The results provide useful clues and a valuable toolkit for further characterization and dissection of the regulatory complex that modulates the pathogenesis and persistence of this important bacterial pathogen.

  20. A NEW STRAIN OF TRANSMISSIBLE LEUCEMIA IN FOWLS (STRAIN H).

    Science.gov (United States)

    Ellermann, V

    1921-03-31

    1. A new strain of fowl leucosis has been transmitted through twelve generations of fowls. 2. An increase in virulence was observed during its passage. This was shown in a shortening of the interval between inoculation and death. The increase in virulence does not affect the number of successful inoculations, which remains approximately constant in from 20 to 40 per cent of the birds employed. 3. As with former strains, the disease manifests itself in various forms; i.e., myeloid and intravascular lymphoid types. A single lymphatic case was observed. 4. In several intravascular cases a diminution in the hemolytic power of the serum was established. This phenomenon was absent in a number of myeloid cases. 5. Active immunization cannot be produced by means of the subcutaneous injection of virulent material. 6. The finding of previous experiments that the virus is filterable has been confirmed. 7. The inoculation of human leucemic material into fowls gave negative results.

  1. A comprehensive study on the role of the Yersinia pestis virulence markers in an animal model of pneumonic plague

    NARCIS (Netherlands)

    W.E. Kaman (Wendy); S. Hawkey; D. van der Kleij (Desiree); M.P. Broekhuijsen; N.J. Silman; F.J. Bikker (Floris)

    2011-01-01

    textabstractWe determined the role of Yersinia pestis virulence markers in an animal model of pneumonic plague. Eleven strains of Y. pestis were characterized using PCR assays to detect the presence of known virulence genes both encoded by the three plasmids as well as chromosomal markers. The

  2. Does Virulence Assessment of Vibrio anguillarum Using Sea Bass (Dicentrarchus labrax) Larvae Correspond with Genotypic and Phenotypic Characterization?

    DEFF Research Database (Denmark)

    Frans, Ingeborg; Dierckens, Kristof; Crauwels, Sam

    2013-01-01

    or phenotypic characteristics, illustrating the complexity of V. anguillarum virulence. Moreover, the standardized gnotobiotic system used in this study has proven its strength as a model to assess and compare the virulence of different V. anguillarum strains in vivo. In this way, the bioassay contributes...

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

    Science.gov (United States)

    Bidet, P; Bonarcorsi, S; Bingen, E

    2012-11-01

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

  4. Molecular Characterization of Putative Virulence Determinants in Burkholderia pseudomallei

    Directory of Open Access Journals (Sweden)

    Suat Moi Puah

    2014-01-01

    Full Text Available The Gram-negative saprophyte Burkholderia pseudomallei is the causative agent of melioidosis, an infectious disease which is endemic in Southeast Asia and northern Australia. This bacterium possesses many virulence factors which are thought to contribute to its survival and pathogenicity. Using a virulent clinical isolate of B. pseudomallei and an attenuated strain of the same B. pseudomallei isolate, 6 genes BPSL2033, BP1026B_I2784, BP1026B_I2780, BURPS1106A_A0094, BURPS1106A_1131, and BURPS1710A_1419 were identified earlier by PCR-based subtractive hybridization. These genes were extensively characterized at the molecular level, together with an additional gene BPSL3147 that had been identified by other investigators. Through a reverse genetic approach, single-gene knockout mutants were successfully constructed by using site-specific insertion mutagenesis and were confirmed by PCR. BPSL2033::Km and BURPS1710A_1419::Km mutants showed reduced rates of survival inside macrophage RAW 264.7 cells and also low levels of virulence in the nematode infection model. BPSL2033::Km demonstrated weak statistical significance (P=0.049 at 8 hours after infection in macrophage infection study but this was not seen in BURPS1710A_1419::Km. Nevertheless, complemented strains of both genes were able to partially restore the gene defects in both in vitro and in vivo studies, thus suggesting that they individually play a minor role in the virulence of B. pseudomallei.

  5. Uncovering the components of the Francisella tularensis Virulence stealth strategy

    Directory of Open Access Journals (Sweden)

    Bradley D Jones

    2014-03-01

    Full Text Available Over the last decade, studies on the virulence of the highly pathogenic intracellular bacterial pathogen Francisella tularensis have increased dramatically. The organism produces an inert LPS, a capsule, escapes the phagosome to grow in the cytosol (encoded by the FPI genes of a variety of host cell types that include epithelial, endothelial, dendritic, macrophage and neutrophil. This review focuses on the work that has identified and characterized individual virulence factors of this organism and we hope to highlight how these factors collectively function to produce the pathogenic strategy of this pathogen. In addition, several recent studies have been published characterizing F. tularensis mutants that induce host immune responses not observed in wild type F. tularensis strains that can induce protection against challenge with virulent F. tularensis. As more detailed studies with attenuated strains are performed, it will be possible to see how host models develop acquired immunity to Francisella. Collectively, detailed insights into the mechanisms of virulence of this pathogen are emerging that will allow the design of anti-infective strategies.

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

    Science.gov (United States)

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

    2014-02-01

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

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

    DEFF Research Database (Denmark)

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

    2017-01-01

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

  8. [Evolutionary engineering in Salmonella: emergence of hybrid virulence-resistance plasmids in non-typhoid serotypes].

    Science.gov (United States)

    Mendoza, María Del Carmen; Herrero, Ana; Rodicio, María Rosario

    2009-01-01

    An example of evolutive engineering in bacterial pathogens is the emergence of hybrid virulence-resistance (VR) plasmids in Salmonella enterica, resulting from an association between antimicrobial resistance determinants and specific virulence plasmids of the S. typhimurium and S. choleraesuis serotypes. VR plasmids all possess the spv (Salmonella plasmid virulence) operon, which is involved in systemic infection; however, they differ in the presence of other virulence determinants and in the resistance gene profile. VR plasmids of S. typhimurium have been found in Europe, and show resistance regions with different levels of complexity that can include class 1 integrons and various transposons. VR plasmids of S. choleraesuis, detected in strains isolated in Taiwan, only confer resistance to ampicillin and sulfonamides. Both serotypes are zoonotic and the presence of hybrid VR plasmids may confer an adaptive advantage under certain conditions, resulting in bacterial strains that are more difficult to treat and have a higher epidemic potential.

  9. Modification of a virulence-associated phenotype after growth of Listeria monocytogenes on food.

    Science.gov (United States)

    Midelet-Bourdin, G; Leleu, G; Copin, S; Roche, S M; Velge, P; Malle, P

    2006-08-01

    To assess the effect of different foods, which have been implicated or not in cases of listeriosis, on the in vitro virulence-associated phenotype level of different Listeria monocytogenes strains. The virulence-associated phenotype level of L. monocytogenes was studied with the in vitro cell test based on a plaque-forming assay with a human adenocarcinoma cell line (HT-29) monolayer. Three strains of L. monocytogenes were grown in preparations (homogenate, 1-mum filtrate or 0.2-mum filtrate) of different food extracts ['rillettes' (potted minced pork), milk, raw salmon and cold-smoked salmon] or in a control medium, brain heart infusion (BHI). The bacterial suspensions grown in food extracts or in BHI at 37 degrees C were diluted with their growth medium (food extract or BHI) or with minimum essential medium before seeding on confluent HT-29 cell monolayers. Filtration of food extracts had no significant effect on the plaque numbers formed by the bacteria. A significant decrease in the plaque numbers was noted for the three strains when they grew in the rillettes extracts, compared with the other food extracts and BHI. The levels of in vitro virulence-associated phenotype of the strains after growth in the rillettes extract were similar to or lower than that of the hypovirulent internal reference strain L. monocytogenes 442. After growth in milk and cold-smoked salmon, the impact on virulence-associated phenotype depended on the strain. In contrast, plaque-forming assay indicated increased virulence-associated phenotype when the strains were switched from a nutrient-rich medium (food extract or BHI) to a minimum essential medium. In vitro virulence-associated phenotype level of the studied strains grown in BHI or cold-smoked salmon was the same as the control virulent strain EGD. In contrast, the nutrients present in rillettes may therefore substantially reduce the number of plaques but not the growth of L. monocytogenes. The utilization of minimum essential

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

    Directory of Open Access Journals (Sweden)

    Maria eBartolomeu

    2016-03-01

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

  11. Route of infection alters virulence of neonatal septicemia Escherichia coli clinical isolates

    Science.gov (United States)

    Cole, Bryan K.; Scott, Edgar; Ilikj, Marko; Bard, David; Akins, Darrin R.; Dyer, David W.

    2017-01-01

    Escherichia coli is the leading cause of Gram-negative neonatal septicemia in the United States. Invasion and passage across the neonatal gut after ingestion of maternal E. coli strains produce bacteremia. In this study, we compared the virulence properties of the neonatal E. coli bacteremia clinical isolate SCB34 with the archetypal neonatal E. coli meningitis strain RS218. Whole-genome sequencing data was used to compare the protein coding sequences among these clinical isolates and 33 other representative E. coli strains. Oral inoculation of newborn animals with either strain produced septicemia, whereas intraperitoneal injection caused septicemia only in pups infected with RS218 but not in those injected with SCB34. In addition to being virulent only through the oral route, SCB34 demonstrated significantly greater invasion and transcytosis of polarized intestinal epithelial cells in vitro as compared to RS218. Protein coding sequences comparisons highlighted the presence of known virulence factors that are shared among several of these isolates, and revealed the existence of proteins exclusively encoded in SCB34, many of which remain uncharacterized. Our study demonstrates that oral acquisition is crucial for the virulence properties of the neonatal bacteremia clinical isolate SCB34. This characteristic, along with its enhanced ability to invade and transcytose intestinal epithelium are likely determined by the specific virulence factors that predominate in this strain. PMID:29236742

  12. Route of infection alters virulence of neonatal septicemia Escherichia coli clinical isolates.

    Directory of Open Access Journals (Sweden)

    Bryan K Cole

    Full Text Available Escherichia coli is the leading cause of Gram-negative neonatal septicemia in the United States. Invasion and passage across the neonatal gut after ingestion of maternal E. coli strains produce bacteremia. In this study, we compared the virulence properties of the neonatal E. coli bacteremia clinical isolate SCB34 with the archetypal neonatal E. coli meningitis strain RS218. Whole-genome sequencing data was used to compare the protein coding sequences among these clinical isolates and 33 other representative E. coli strains. Oral inoculation of newborn animals with either strain produced septicemia, whereas intraperitoneal injection caused septicemia only in pups infected with RS218 but not in those injected with SCB34. In addition to being virulent only through the oral route, SCB34 demonstrated significantly greater invasion and transcytosis of polarized intestinal epithelial cells in vitro as compared to RS218. Protein coding sequences comparisons highlighted the presence of known virulence factors that are shared among several of these isolates, and revealed the existence of proteins exclusively encoded in SCB34, many of which remain uncharacterized. Our study demonstrates that oral acquisition is crucial for the virulence properties of the neonatal bacteremia clinical isolate SCB34. This characteristic, along with its enhanced ability to invade and transcytose intestinal epithelium are likely determined by the specific virulence factors that predominate in this strain.

  13. Route of infection alters virulence of neonatal septicemia Escherichia coli clinical isolates.

    Science.gov (United States)

    Cole, Bryan K; Scott, Edgar; Ilikj, Marko; Bard, David; Akins, Darrin R; Dyer, David W; Chavez-Bueno, Susana

    2017-01-01

    Escherichia coli is the leading cause of Gram-negative neonatal septicemia in the United States. Invasion and passage across the neonatal gut after ingestion of maternal E. coli strains produce bacteremia. In this study, we compared the virulence properties of the neonatal E. coli bacteremia clinical isolate SCB34 with the archetypal neonatal E. coli meningitis strain RS218. Whole-genome sequencing data was used to compare the protein coding sequences among these clinical isolates and 33 other representative E. coli strains. Oral inoculation of newborn animals with either strain produced septicemia, whereas intraperitoneal injection caused septicemia only in pups infected with RS218 but not in those injected with SCB34. In addition to being virulent only through the oral route, SCB34 demonstrated significantly greater invasion and transcytosis of polarized intestinal epithelial cells in vitro as compared to RS218. Protein coding sequences comparisons highlighted the presence of known virulence factors that are shared among several of these isolates, and revealed the existence of proteins exclusively encoded in SCB34, many of which remain uncharacterized. Our study demonstrates that oral acquisition is crucial for the virulence properties of the neonatal bacteremia clinical isolate SCB34. This characteristic, along with its enhanced ability to invade and transcytose intestinal epithelium are likely determined by the specific virulence factors that predominate in this strain.

  14. Virulence Genes Profile of Multidrug Resistant Pseudomonas aeruginosa Isolated from Iranian Children with UTIs

    Directory of Open Access Journals (Sweden)

    Zohreh Heidary

    2016-04-01

    Full Text Available Virulent and resistant strains Pseudomonas aeruginosa (P. aeruginosa is one of the most important cause of UTIs in pediatrics. The present study was carried to investigate the frequency of virulence factors in the multi-drug resistant strains of P. aeruginosa isolated from pediatrics hospitalized due to the UTIs. One - hundred and forty three urine samples were collected from pediatric patients suffered from UTIs. Samples were cultured and those that were P. aeruginosa positive were analyzed for the presence of putative virulence genes. Seventy one out of 143 samples (49.65% were positive for P. aeruginosa. Monthly, sex and age-dependent prevalence were seen for P. aeruginosa. Bacterial strains had the highest levels of resistance against ampicillin (95.77%, gentamicin (92.95% and ciprofloxacin (81.69%. Of 71 P. aeruginosa isolates, 12 strains were resistant to more than 9 antibiotics (16.90%. The most commonly detected virulence factors in the cases of urethral infections were exoU and plcH while those of pyelonephritis and cystitis were were exoS and lasB. Our findings should raise awareness about antibiotic resistance in hospitalized pediatrics with UTIs in Iran. Clinicians should exercise caution in prescribing antibiotics, especially in cases of UTIs. Such information can help in identifying these virulence genes as useful diagnostic markers for clinical P. aeruginosa strains isolated from UTIs.

  15. Effect of cyclophosphamide on infections produced by Escherichia coli of high and low virulence in chickens.

    Science.gov (United States)

    Nakamura, K; Imada, Y; Abe, F

    1987-01-01

    The effect of cyclophosphamide (Cy) on infections caused by Escherichia coli strains of high (Expt 1) and low (Expt 2) virulence was examined in 4-week-old specified-pathogen-free chickens. In Expt 1 the mortalities of Cy-treated and non-treated chickens given 5 x 10(7) cfu of a strain of E. coli of high virulence were both 100%. In the groups given 5 x 10(5) cfu, the mortality of Cy-treated chickens was 90% and that of non-treated chickens was 10%. In Expt 2 the groups given 1 x 10(9) cfu of an E. coli strain of low virulence showed a mortality of 30% when treated with Cy and 0% when non-treated. The chickens given 5 x 10(7) or 5 x 10(5) cfu showed no mortality, clinical signs or histological lesions. Cy-treated chickens showed severe hypoplasia of granulopoiesis in the bone marrow. Haematological examination of Cy-treated chickens revealed leukopenia, especially lymphopenia, and thrombocytopenia. This study suggests that Cy treatment may enhance infection caused by E. coli strain of high virulence and manifest signs of infection caused by E. coli strain of low virulence in the chickens.

  16. Spontaneous Loss of Virulence in Natural Populations of Listeria monocytogenes.

    Science.gov (United States)

    Maury, Mylène M; Chenal-Francisque, Viviane; Bracq-Dieye, Hélène; Han, Lei; Leclercq, Alexandre; Vales, Guillaume; Moura, Alexandra; Gouin, Edith; Scortti, Mariela; Disson, Olivier; Vázquez-Boland, José A; Lecuit, Marc

    2017-11-01

    The pathogenesis of Listeria monocytogenes depends on the ability of this bacterium to escape from the phagosome of the host cells via the action of the pore-forming toxin listeriolysin O (LLO). Expression of the LLO-encoding gene ( hly ) requires the transcriptional activator PrfA, and both hly and prfA genes are essential for L. monocytogenes virulence. Here, we used the hemolytic activity of LLO as a phenotypic marker to screen for spontaneous virulence-attenuating mutations in L. monocytogenes Sixty nonhemolytic isolates were identified among a collection of 57,820 confirmed L. monocytogenes strains isolated from a variety of sources (0.1%). In most cases (56/60; 93.3%), the nonhemolytic phenotype resulted from nonsense, missense, or frameshift mutations in prfA Five strains carried hly mutations leading to a single amino acid substitution (G299V) or a premature stop codon causing strong virulence attenuation in mice. In one strain, both hly and gshF (encoding a glutathione synthase required for full PrfA activity) were missing due to genomic rearrangements likely caused by a transposable element. The PrfA/LLO loss-of-function (PrfA - /LLO - ) mutants belonged to phylogenetically diverse clades of L. monocytogenes , and most were identified among nonclinical strains (57/60). Consistent with the rare occurrence of loss-of-virulence mutations, we show that prfA and hly are under purifying selection. Although occurring at a low frequency, PrfA - /LLO - mutational events in L. monocytogenes lead to niche restriction and open an evolutionary path for obligate saprophytism in this facultative intracellular pathogen. Copyright © 2017 Maury et al.

  17. New Role for DCR-1/Dicer in Caenorhabditis elegans Innate Immunity against the Highly Virulent Bacterium Bacillus thuringiensis DB27

    OpenAIRE

    Iatsenko, Igor; Sinha, Amit; Rödelsperger, Christian; Sommer, Ralf J.

    2013-01-01

    Bacillus thuringiensis produces toxins that target invertebrates, including Caenorhabditis elegans. Virulence of Bacillus strains is often highly specific, such that B. thuringiensis strain DB27 is highly pathogenic to C. elegans but shows no virulence for another model nematode, Pristionchus pacificus. To uncover the underlying mechanisms of the differential responses of the two nematodes to B. thuringiensis DB27 and to reveal the C. elegans defense mechanisms against this pathogen, we condu...

  18. Higher resource level promotes virulence in an environmentally transmitted bacterial fish pathogen.

    Science.gov (United States)

    Kinnula, Hanna; Mappes, Johanna; Valkonen, Janne K; Pulkkinen, Katja; Sundberg, Lotta-Riina

    2017-06-01

    Diseases have become a primary constraint to sustainable aquaculture, but remarkably little attention has been paid to a broad class of pathogens: the opportunists. Opportunists often persist in the environment outside the host, and their pathogenic features are influenced by changes in the environment. To test how environmental nutrient levels influence virulence, we used strains of Flavobacterium columnare, an environmentally transmitted fish pathogen, to infect rainbow trout and zebra fish in two different nutrient concentrations. To separate the effects of dose and nutrients, we used three infective doses and studied the growth of bacteria in vitro. High nutrient concentration promoted both the virulence and the outside-host growth of the pathogen, most notably in a low-virulence strain. The increase in virulence could not be exhaustively explained by the increased dose under higher nutrient supply, suggesting virulence factor activation. In aquaculture settings, accumulation of organic material in rearing units can locally increase water nutrient concentration and therefore increase disease risk as a response to elevated bacterial density and virulence factor activation. Our results highlight the role of increased nutrients in outside-host environment as a selective agent for higher virulence and faster evolutionary rate in opportunistic pathogens.

  19. Map-based comparative genomic analysis of virulent haemophilus parasuis serovars 4 and 5.

    Science.gov (United States)

    Lawrence, Paulraj; Bey, Russell

    2015-01-01

    Haemophilus parasuis is a commensal bacterium of the upper respiratory tract of healthy pigs. However, in conjunction with viral infections in immunocompromised animals H. parasuis can transform into a pathogen that is responsible for causing Glasser's disease which is typically characterized by fibrinous polyserositis, polyarthritis, meningitis and sometimes acute pneumonia and septicemia in pigs. Haemophilus parasuis serovar 5 is highly virulent and more frequently isolated from respiratory and systemic infection in pigs. Recently a highly virulent H. parasuis serovar 4 was isolated from the tissues of diseased pigs. To understand the differences in virulence and virulence-associated genes between H. parasuis serovar 5 and highly virulent H. parasuis serovar 4 strains, a genomic library was generated by TruSeq preparation and sequenced on Illumina HiSeq 2000 obtaining 50 bp PE reads. A three-way comparative genomic analysis was conducted between two highly virulent H. parasuis serovar 4 strains and H. parasuis serovar 5. Haemophilus parasuis serovar 5 GenBank isolate SH0165 (GenBank accession number CP001321.1) was used as reference strain for assembly. Results of these analysis revealed the highly virulent H. parasuis serovar 4 lacks genes encoding for, glycosyl transferases, polysaccharide biosynthesis protein capD, spore coat polysaccharide biosynthesis protein C, polysaccharide export protein and sialyltransferase which can modify the lipopolysaccharide forming a short-chain LPS lacking O-specific polysaccharide chains often referred to as lipooligosaccharide (LOS). In addition, it can modify the outer membrane protein (OMP) structure. The lack of sialyltransferase significantly reduced the amount of sialic acid incorporated into LOS, a major and essential component of the cell wall and an important virulence determinant. These molecules may be involved in various stages of pathogenesis through molecular mimicry and by causing host cell cytotoxicity, reduced

  20. Thioridazine protects the mouse from a virulent infection by Salmonella enterica serovar Typhimurium 74

    DEFF Research Database (Denmark)

    Dasgupta, Asish; Mukherjee, Sayanti; Chaki, Shaswati

    2010-01-01

    When administered to mice at doses of 100microg/mouse and 200microg/mouse, thioridazine (TDZ) significantly protected animals from the lethality produced by a virulent strain of Salmonella enterica serovar Typhimurium and reduced the number of bacteria retrieved from the spleen, liver and heart...... blood. The protection conferred by TDZ against a virulent Salmonella infection is hypothesised to be due to a reduction in the 55kDa virulence protein of the outer membrane of the organism, as this protein is almost totally absent when the organism is exposed to the phenothiazine. It is further...

  1. Eugenol exhibits anti-virulence properties by competitively binding to quorum sensing receptors.

    Science.gov (United States)

    Rathinam, Prasanth; Vijay Kumar, H S; Viswanathan, Pragasam

    2017-09-01

    The primary objective of this study was to ascertain the anti-biofilm and anti-virulence properties of sub-minimum inhibitory concentration (MIC) levels of eugenol against the standard strain PAO1 and two multi-drug resistant P. aeruginosa clinical isolates utilizing quorum sensing inhibition (QSI). Eugenol at 400 μM significantly reduced biofilm formation on urinary catheters and the virulence factors (VF) including extracellular polysaccharides, rhamnolipid, elastase, protease, pyocyanin, and pyoverdine (p associated genes besides the VF genes (p < 0.001). This study provides insights, for the first time, into the mechanism of the anti-virulence properties of eugenol.

  2. Comparative genomic analysis of Vibrio parahaemolyticus: serotype conversion and virulence

    Directory of Open Access Journals (Sweden)

    Gil Ana I

    2011-06-01

    Full Text Available Abstract Background Vibrio parahaemolyticus is a common cause of foodborne disease. Beginning in 1996, a more virulent strain having serotype O3:K6 caused major outbreaks in India and other parts of the world, resulting in the emergence of a pandemic. Other serovariants of this strain emerged during its dissemination and together with the original O3:K6 were termed strains of the pandemic clone. Two genomes, one of this virulent strain and one pre-pandemic strain have been sequenced. We sequenced four additional genomes of V. parahaemolyticus in this study that were isolated from different geographical regions and time points. Comparative genomic analyses of six strains of V. parahaemolyticus isolated from Asia and Peru were performed in order to advance knowledge concerning the evolution of V. parahaemolyticus; specifically, the genetic changes contributing to serotype conversion and virulence. Two pre-pandemic strains and three pandemic strains, isolated from different geographical regions, were serotype O3:K6 and either toxin profiles (tdh+, trh- or (tdh-, trh+. The sixth pandemic strain sequenced in this study was serotype O4:K68. Results Genomic analyses revealed that the trh+ and tdh+ strains had different types of pathogenicity islands and mobile elements as well as major structural differences between the tdh pathogenicity islands of the pre-pandemic and pandemic strains. In addition, the results of single nucleotide polymorphism (SNP analysis showed that 94% of the SNPs between O3:K6 and O4:K68 pandemic isolates were within a 141 kb region surrounding the O- and K-antigen-encoding gene clusters. The "core" genes of V. parahaemolyticus were also compared to those of V. cholerae and V. vulnificus, in order to delineate differences between these three pathogenic species. Approximately one-half (49-59% of each species' core genes were conserved in all three species, and 14-24% of the core genes were species-specific and in different

  3. Identification of virulence genes carried by bacteriophages obtained from clinically isolated methicillin-resistant Staphylococcus aureus.

    Science.gov (United States)

    Karasartova, Djursun; Cavusoglu, Zeynep Burcin; Turegun, Buse; Ozsan, Murat T; Şahin, Fikret

    2016-12-01

    Bacteriophages play an important role in the pathogenicity of Staphylococcus aureus (S. aureus) either by carrying accessory virulence factors or several superantigens. Despite their importance, there are not many studies showing the actual distribution of the virulence genes carried by the prophages obtained from the clinically isolated Staphylococcus. In this study, we investigated prophages obtained from methicillin-resistant S. aureus (MRSA) strains isolated from hospital- and community-associated (HA-CA) infections for the virulence factors. In the study, 43 phages isolated from 48 MRSA were investigated for carrying toxin genes including the sak, eta, lukF-PV, sea, selp, sek, seg, seq chp, and scn virulence genes using polymerase chain reaction (PCR) and Southern blot. Restriction fragment length polymorphism was used to analyze phage genomes to investigate the relationship between the phage profiles and the toxin genes' presence. MRSA strains isolated from HA infections tended to have higher prophage presence than the MRSA strains obtained from the CA infections (97% and 67%, respectively). The study showed that all the phages with the exception of one phage contained one or more virulence genes in their genomes with different combinations. The most common toxin genes found were sea (83%) followed by sek (77%) and seq (64%). The study indicates that prophages encode a significant proportion of MRSA virulence factors.

  4. Virulence of endemic nonpigmented northern Australian Staphylococcus aureus clone (clonal complex 75, S. argenteus) is not augmented by staphyloxanthin.

    Science.gov (United States)

    Tong, Steven Y C; Sharma-Kuinkel, Batu K; Thaden, Joshua T; Whitney, Adeline R; Yang, Soo-Jin; Mishra, Nagendra N; Rude, Thomas; Lilliebridge, Rachael A; Selim, Maria A; Ahn, Sun Hee; Holt, Deborah C; Giffard, Philip M; Bayer, Arnold S; Deleo, Frank R; Fowler, Vance G

    2013-08-01

    Staphylococcus aureus clonal complex 75 (herein referred to as S. argenteus) lacks the carotenoid pigment operon, crtOPQMN, responsible for production of the putative virulence factor, staphyloxanthin. Although a common cause of community-onset skin infections among Indigenous populations in northern Australia, this clone is infrequently isolated from hospital-based patients with either bacteremic or nonbacteremic infections. We hypothesized that S. argenteus would have attenuated virulence compared to other S. aureus strains due to its staphyloxanthin "deficiency." Compared to prototypical S. aureus strains, S. argenteus was more susceptible to oxidative stress and neutrophil killing in vitro and had reduced virulence in murine sepsis and skin infection models. Transformation with pTX-crtOPQMN resulted in staphyloxanthin expression and increased resistance to oxidative stress in vitro. However, neither resistance to neutrophil killing nor in vivo virulence was increased. Thus, reduced virulence of S. argenteus in these models is due to mechanisms unrelated to lack of staphyloxanthin production.

  5. Bioinformatics for Diagnostics, Forensics, and Virulence Characterization and Detection

    Energy Technology Data Exchange (ETDEWEB)

    Gardner, S; Slezak, T

    2005-04-05

    We summarize four of our group's high-risk/high-payoff research projects funded by the Intelligence Technology Innovation Center (ITIC) in conjunction with our DHS-funded pathogen informatics activities. These are (1) quantitative assessment of genomic sequencing needs to predict high quality DNA and protein signatures for detection, and comparison of draft versus finished sequences for diagnostic signature prediction; (2) development of forensic software to identify SNP and PCR-RFLP variations from a large number of viral pathogen sequences and optimization of the selection of markers for maximum discrimination of those sequences; (3) prediction of signatures for the detection of virulence, antibiotic resistance, and toxin genes and genetic engineering markers in bacteria; (4) bioinformatic characterization of virulence factors to rapidly screen genomic data for potential genes with similar functions and to elucidate potential health threats in novel organisms. The results of (1) are being used by policy makers to set national sequencing priorities. Analyses from (2) are being used in collaborations with the CDC to genotype and characterize many variola strains, and reports from these collaborations have been made to the President. We also determined SNPs for serotype and strain discrimination of 126 foot and mouth disease virus (FMDV) genomes. For (3), currently >1000 probes have been predicted for the specific detection of >4000 virulence, antibiotic resistance, and genetic engineering vector sequences, and we expect to complete the bioinformatic design of a comprehensive ''virulence detection chip'' by August 2005. Results of (4) will be a system to rapidly predict potential virulence pathways and phenotypes in organisms based on their genomic sequences.