A novel adhesive factor contributing to the virulence of Vibrio parahaemolyticus.
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ABSTRACT:
SUBMITTER: Liu M
PROVIDER: S-EPMC4585867 | biostudies-other | 2015 Sep
REPOSITORIES: biostudies-other
Publications
A novel adhesive factor contributing to the virulence of Vibrio parahaemolyticus.
Scientific reports 20150924
Bacterial adhesins play a pivotal role in the tight bacteria-host cells attachment to initiate the downstream processes and bacterial infection of hosts. In this study, we identified a novel adhesin, VpadF in V. parahaemolyticus. Deletion of VpadF in V. parahaemolyticus markedly impaired its attachment and cytotoxicity to epithelial cells, as well as attenuated the virulence in murine model. Biochemical studies revealed that VpadF recognized both fibronectin and fibrinogen. The binding of VpadF ...[more]
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Project description:Vibrio parahaemolyticus is a causative agent of serious human seafood-borne gastroenteritis disease and even death. In this study, for the first time, we obtained the secretomic profiles of seven V. parahaemolyticus strains of clinical and food origins. The strains exhibited various toxic genotypes and phenotypes of antimicrobial susceptibility and heavy metal resistance, five of which were isolated from aquatic products in Shanghai, China. Fourteen common extracellular proteins were identified from the distinct secretomic profiles using the two-dimensional gel electrophoresis (2-DE) and liquid chromatography tandem mass spectrometry (LC-MS/MS) techniques. Of these, half were involved in protein synthesis and sugar transport of V. parahaemolyticus. Strikingly, six identified proteins were virulence-associated factors involved in the pathogenicity of some other pathogenic bacteria, including the translation elongation factor EF-Tu, pyridoxine 5'-phosphate synthase, σ(54) modulation protein, dihydrolipoyl dehydrogenase, transaldolase and phosphoglycerate kinase. In addition, comparative secretomics also revealed several extracellular proteins that have not been described in any bacteria, such as the ribosome-recycling factor, translation elongation factor EF-Ts, phosphocarrier protein HPr and maltose-binding protein MalE. The results in this study will facilitate the better understanding of the pathogenesis of V. parahaemolyticus and provide data in support of novel vaccine candidates against the leading seafood-borne pathogen worldwide.
| S-EPMC4505105 | biostudies-literature
Project description:Translucent post-larvae disease (TPD), caused by Vibrio parahaemolyticus (Vp TPD), has become an emerging shrimp disease, affecting more than 70%-80% of coastal shrimp nurseries in China in spring 2020. Here, we investigated the key virulence factors of Vp TPD by analyzing protein fragments, related genomic information, as well as experimental challenge tests. After investigating the toxic effects of purified protein fragments with different molecular weights (MWs) from Vp TPD, we found that only the protein fragments with MW >100 kDa showed similar lethality to live Vp TPD in the experimental challenge test using post-larvae shrimp. Meanwhile, similar histopathological changes exhibiting in the hepatopancreas and midgut of the diseased individuals were observed in the post-larvae shrimp challenged with either bacterial protein fragments (MW >100 kDa) or live Vp TPD. Based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometry analyses, two novel proteins, Vibrio high virulent protein (VHVP)-1 and VHVP-2, were identified as the candidates of key virulence factors to cause TPD. Moreover, VHVP-1 and VHVP-2 were found to be encoded by two genes (vhvp-1 and vhvp-2) tandemly located on a 187,791-bp plasmid and were predicted to depend on the same promoter following a comparative genomic analysis. Further epidemiological investigation and challenge test indicated that the V. parahaemolyticus isolate carrying only the vhvp-1 gene and lacking vhvp-2 gene could not cause mortality of experimental Penaeus vannamei post-larvae. The mutant (Δvhvp-2) by deleting vhvp-2 gene could only cause 4.92% of accumulative mortality of post-larvae that is similar to the non-Vp TPD Vibrio strain. Additionally, the complemented strains, Δvhvp-2/pBT3-vhvp-2 and Δvhvp-2/pwtCas9-vhvp-2, showed similar virulence to the wild-type Vp TPD. The results demonstrated that V. parahaemolyticus becomes lethal to post-larval shrimp by acquiring the VHVP-2 virulence factor. This study sheds light on further investigations of the pathogenic mechanism of Vp TPD and the development of strategies for early diagnosis of TPD in shrimp hatcheries. As a severe emerging shrimp disease, TPD has heavily impacted the shrimp aquaculture industry and resulted in serious economic losses in China since spring 2020. This study aimed to identify the key virulent factors and related genes of the Vp TPD, for a better understanding of its pathogenicity of the novel highly lethal infectious pathogen, as well as its molecular epidemiological characteristics in China. The present study revealed that a novel protein, Vibrio high virulent protein-2 (MW >100 kDa), is responsible to the lethal virulence of V. parahaemolyticus to shrimp post-larvae. The results are essential for effectively diagnosing and monitoring novel pathogenic bacteria, like Vp TPD, in aquaculture shrimps and would be beneficial to the fisheries department in early warning of Vp TPD emergence and developing prevention strategies to reduce economic losses due to severe outbreaks of TPD. Elucidation of the key virulence genes and genomics of Vp TPD could also provide valuable information on the evolution and ecology of this emerging pathogen in aquaculture environments.
| S-EPMC10714935 | biostudies-literature
Project description:BackgroundVibrio 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.ResultsGenomic 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 functional categories.ConclusionsOur data support the idea that the pandemic strains are closely related and that recent South American outbreaks of foodborne disease caused by V. parahaemolyticus are closely linked to outbreaks in India. Serotype conversion from O3:K6 to O4:K68 was likely due to a recombination event involving a region much larger than the O-antigen- and K-antigen-encoding gene clusters. Major differences between pathogenicity islands and mobile elements are also likely driving the evolution of V. parahaemolyticus. In addition, our analyses categorized genes that may be useful in differentiating pathogenic Vibrios at the species level.
| S-EPMC3130711 | biostudies-literature
Project description:BackgroundV. parahaemolyticus is autochthonous to the marine environment and causes seafood-borne gastroenteritis in humans. Generally, V. parahaemolyticus recovered from the environment and/or seafood is thought to be non-pathogenic and the relationship between environmental isolates and acute diarrhoeal disease is poorly understood. In this study, we explored the virulence potential of environmental V. parahaemolyticus isolated from water, plankton and assorted seafood samples collected from the Indian coast.ResultsTwenty-two V. parahaemolyticus isolates from seafood harboured virulence associated genes encoding the thermostable-direct haemolysin (TDH), TDH-related haemolysin (TRH), and Type 3 secretion systems (T3SS) and 95.5% of the toxigenic isolates had pandemic strain attributes (toxRS/new+). Nine serovars, with pandemic strain traits were newly identified and an O4:K36 tdh-trh+V. parahaemolyticus bearing pandemic marker gene was recognised for the first time. Results obtained by reverse transcription PCR showed trh, T3SS1 and T3SS2β to be functional in the seafood isolates. Moreover, the environmental strains were cytotoxic and could invade Caco-2 cells upon infection as well as induce changes to the tight junction protein, ZO-1 and the actin cytoskeleton.ConclusionOur study provides evidence that environmental isolates of V. parahaemolyticus are potentially invasive and capable of eliciting pathogenic characteristics typical of clinical strains and present a potential health risk. We also demonstrate that virulence of this pathogen is highly complex and hence draws attention for the need to investigate more reliable virulence markers in order to distinguish the environmental and clinical isolates, which will be crucial for the pathogenomics and control of this pathogen.
| S-EPMC7092547 | biostudies-literature
Project description:In this study, 77 clinical and 67 oyster Vibrio parahaemolyticus isolates from North America were examined for biochemical profiles, serotype, and the presence of potential virulence factors (tdh, trh, and type III secretion system [T3SS] genes). All isolates were positive for oxidase, indole, and glucose fermentation, consistent with previous reports. The isolates represented 35 different serotypes, 9 of which were shared by clinical and oyster isolates. Serotypes associated with pandemic strains (O1:KUT, O1:K25, O3:K6, and O4:K68) were observed for clinical isolates, and 7 (9%) oyster isolates belonged to serotype O1:KUT. Of the clinical isolates, 27% were negative for tdh and trh, while 45% contained both genes. Oyster isolates were preferentially selected for the presence of tdh and/or trh; 34% contained both genes, 42% had trh but not tdh, and 3% had tdh but not trh. All but 1 isolate (143/144) had at least three of the four T3SS1 genes examined. The isolates lacking both tdh and trh contained no T3SS2? or T3SS2? genes. All clinical isolates positive for tdh and negative for trh possessed all T3SS2? genes, and all isolates negative for tdh and positive for trh possessed all T3SS2? genes. The two oyster isolates containing tdh but not trh possessed all but the vopB2 gene of T3SS2?, as reported previously. In contrast to the findings of previous studies, all strains examined that were positive for both tdh and trh also carried T3SS2? genes. This report identifies the serotype as the most distinguishing feature between clinical and oyster isolates. Our findings raise concerns about the reliability of the tdh, trh, and T3SS genes as virulence markers and highlight the need for more-detailed pathogenicity investigations of V. parahaemolyticus.
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Project description:Non-toxigenic V. parahaemolyticus isolates (tdh-/trh-/T3SS2-) have recently been isolated from patients with gastroenteritis. In this study we report that the larvae of the wax moth (Galleria mellonella) are susceptible to infection by toxigenic or non-toxigenic clinical isolates of V. parahaemolyticus. In comparison larvae inoculated with environmental isolates of V. parahaemolyticus did not succumb to disease. Whole genome sequencing of clinical non-toxigenic isolates revealed the presence of a gene encoding a nudix hydrolase, identified as mutT. A V. parahaemolyticus mutT mutant was unable to kill G. mellonella at 24 h post inoculation, indicating a role of this gene in virulence. Our findings show that G. mellonella is a valuable model for investigating screening of possible virulence genes of V. parahaemolyticus and can provide new insights into mechanisms of virulence of atypical non-toxigenic V. parahaemolyticus. These findings will allow improved genetic tests for the identification of pathogenic V. parahaemolyticus to be developed and will have a significant impact for the scientific community.
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Project description:Most Vibrio parahaemolyticus isolates found in marine environments are non-pathogenic; however, certain lineages have acquired genomic pathogenicity islands (PAIs) that enable these isolates to cause human illness. The V. parahaemolyticus PAI contains one or both of two toxins: thermostable direct haemolysin (TDH) or TDH-related haemolysin (TRH) and type III secretion system 2 (T3SS2). Recently, a few V. parahaemolyticus isolates that do not have this PAI were obtained from clinical samples, and there has been interest in determining whether these isolates possess novel virulence factors. In this investigation, we have selected four V. parahaemolyticus isolates: a canonical pathogenic strain containing TDH, TRH and T3SS2; two strains from clinical cases which do not contain a PAI; and an environmental isolate which also does not contain a PAI. For each isolate, we analyzed differential gene expression after crude bile exposure. Several enteric bacterial pathogens are known to use bile as a signal to enhance virulence gene expression. We have shown that in the tdh-positive trh-positive pathotype gene virulence gene expression was not up-regulated in response to crude bile, strongly indicating that the current dogma of virulence gene regulation in V. parahaemolyticus needs to be revisited and separately investigated for each pathotype. In addition, we have created a list of genes of interest that were up-regulated in the non-canonical pathotypes which may contribute to virulence in these isolates.
| S-EPMC6096935 | biostudies-literature
Project description:Historically, Vibrio parahaemolyticus infections have been characterized by sporadic cases caused by multiple, diverse serotypes. However, since 1996, V. parahaemolyticus serotype O3:K6 strains have been associated with several large-scale outbreaks of illness, suggesting the emergence of a "new" group of organisms with enhanced virulence. We have applied three different molecular subtyping techniques to identify an appropriate method for differentiating O3:K6 isolates from other serotypes. Pulsed-field gel electrophoresis (PFGE) following NotI digestion differentiated seven closely related subtypes among O3:K6 and related strains, which were distinct from PFGE patterns for non-O3:K6 isolates. Ribotyping and tdh sequencing were less discriminatory than PFGE, but further confirmed close genetic relationships among recent O3:K6 isolates. In vitro adherence and cytotoxicity studies with human epithelial cells showed that O3:K6 isolates exhibited statistically higher levels of adherence and cytotoxicity to host cells than non-O3:K6 isolates. Epithelial cell cytotoxicity patterns were determined with a lactate dehydrogenase release assay. At 3 h postinfection, high relative cytotoxicities (>50% maximum lactate dehydrogenase activity) were found among a greater proportion of recently isolated O3:K6 and closely related strains (75%) than among the non-O3:K6 isolates (23%). A statistically significant relationship between adherence and cytotoxicity suggests that the pathogenic potential of some isolates may be associated with increased adherence to epithelial cells. Our findings suggest that enhanced adherence and cytotoxicity may contribute to the apparent unique pathogenic potential of V. parahaemolyticus O3:K6 strains.
| S-EPMC123939 | biostudies-literature
Project description:Virulence factor genes encoding the thermostable direct hemolysin (tdh) and the thermostable direct hemolysin-related hemolysin (trh) are strongly correlated with virulence of the emergent human pathogen Vibrio parahaemolyticus. The gene encoding the thermolabile hemolysin (tlh) is also considered a signature molecular marker for the species. These genes are typically reported in very low percentages (1 to 2%) of nonclinical strains. V. parahaemolyticus strains were isolated from various niches within a pristine estuary (North Inlet, SC) and were screened for these genes using both newly designed PCR primers and more commonly used primers. DNA sequences of tdh and trh were recovered from 48% and 8.3%, respectively, of these North Inlet strains. The recovery of pathogenic V. parahaemolyticus strains in such high proportions from an estuarine ecosystem that is virtually free of anthropogenic influences indicates the potential for additional, perhaps environmental roles of the tdh and trh genes.
| S-EPMC3623233 | biostudies-literature
Project description:Vibrio parahaemolyticus, a bacterial pathogen, causes human gastroenteritis. A type III secretion system (T3SS2) encoded in pathogenicity island (Vp-PAI) is the main contributor to enterotoxicity and expression of Vp-PAI encoded genes is regulated by two transcriptional regulators, VtrA and VtrB. However, a host-derived inducer for the Vp-PAI genes has not been identified. Here, we demonstrate that bile induces production of T3SS2-related proteins under osmotic conditions equivalent to those in the intestinal lumen. We also show that bile induces vtrA-mediated vtrB transcription. Transcriptome analysis of bile-responsive genes revealed that bile strongly induces expression of Vp-PAI genes in a vtrA-dependent manner. The inducing activity of bile was diminished by treatment with bile acid sequestrant cholestyramine. Finally, we demonstrate an in vivo protective effect of cholestyramine on enterotoxicity and show that similar protection is observed in infection with a different type of V. parahaemolyticus or with non-O1/non-O139 V. cholerae strains of vibrios carrying the same kind of T3SS. In summary, these results provide an insight into how bacteria, through the ingenious action of Vp-PAI genes, can take advantage of an otherwise hostile host environment. The results also reveal a new therapeutic potential for widely used bile acid sequestrants in enteric bacterial infections.
| S-EPMC2954181 | biostudies-literature