Trh Genes Research Articles

Antibiotic resistance of Vibrio parahaemolyticus isolated from pond-reared Litopenaeus vannamei marketed in Natal, Brazil

Ten out of fifty fresh and refrigerated samples of shrimp (Litopenaeus vannamei) collected from retailers in Natal (Rio Grande do Norte, Northeastern Brazil) tested positive for Vibrio parahaemolyticus. The Kanagawa test and multiplex PCR assays were used to detect TDH and TRH hemolysins and the tdh, trh and tlh genes, respectively. All strains were Kanagawa-negative and tlh-positive. Antibiotic susceptibility testing was done for seven antibiotics by the agar diffusion technique. Five strains (50%) presented multiple antibiotic resistance to ampicillin (90%) and amikacin (60%), while two strains (20%) displayed intermediate-level resistance to amikacin. All strains were sensitive to chloramphenicol. Intermediate-level susceptibility and/or resistance to other antibiotics ranged from 10 to 90%, with emphasis on the observed growing intermediate-level resistance to ciprofloxacin. Half our isolates yielded a multiple antibiotic resistance index above 0.2 (range: 0.14-0.29), indicating a considerable risk of propagation of antibiotic resistance throughout the food chain.

IDENTIFICATION TARGETED ON toxR GENE AND DETECTION OF VIRULENT FACTOR ENCODING GENES ON Vibrio parahaemolyticus ISOLATED FROM RAW CHICKEN MEAT

A number of V. parahaemolyticus isolates has been isolated from raw chicken meat samples collected in Pasar raya Padang. Isolation was done using ChromagarTM Vibrio media. Identification of toxR gene was then done to these isolates. toxR is a very specific gene in V. parahaemolyticus species. Detection for the presence of genes encoding virulence factors, in this case were the gene encoding thermostable direct hemolysin (tdh) and TDH related hemolysin (trh) was performed on toxR positive V. parahaemolyticus isolates. Identification of toxR gene and detection of tdh and trh genes were done trough amplification using polymerase chain reaction PCR (method). The results showed that all of the tested V. parahaemolyticus isolates (22 isolates) had toxR gene, but none of isolates has gene encoding the production of virulence factors both tdh and trh.

Seasonal prevalence of Vibrio species in retail shrimps with an emphasis on Vibrio parahaemolyticus

Seasonal prevalence of Vibrio species in shrimp samples from retail outlets in the South-western part of Iran was studied. A total of 300 samples were analyzed (75 samples in each season). Special attention was paid to the prevalence of total and pathogenic Vibrio parahaemolyticus. All the TCBS isolates were first identified to the genus level with PCR and then identified to the species level using a battery of biochemical reactions and tests. To investigate the pathogenicity of the isolated V. parahaemolyticus, multiplex PCR (tl, tdh and trh genes) was performed. Vibrios were detected during the whole investigation period, depending on the sampling season. They were detected in 18.6% of the winter samples, 64% of the spring samples, 70.6% of the summer samples and 41.3% of the autumn samples. Vibrio calviensis and Vibrio alginolyticus were dominant in samples of different seasons, with the average prevalence of 18.6% and 17.6%, respectively. V. parahaemolyticus was found in 4.0% of the winter samples, 13.3% of the spring samples, 18.6% of the summer samples and 8% of the autumn samples. During the period of this study, two tdh-positive strains were isolated, while no trh-positive V. parahaemolyticus strain was detected in samples of different seasons.

Characterization of Vibrio Parahaemolyticus isolated from oysters and mussels in São Paulo, Brazil

Vibrio parahaemolyticus is a marine bacterium, responsible for gastroenteritis in humans. Most of the clinical isolates produce thermostable direct hemolysin (TDH) and TDH-related hemolysin (TRH) encoded by tdh and trh genes respectively. In this study, twenty-three V. parahaemolyticus, previously isolated from oysters and mussels were analyzed by PCR using specific primers for the 16S rRNA and virulence genes (tdh, trh and tlh) and for resistance to different classes of antibiotics and PFGE. Nineteen isolates were confirmed by PCR as V. parahaemolyticus. The tlh gene was present in 100% of isolates, the tdh gene was identified in two (10.5%) isolates, whereas the gene trh was not detected. Each isolate was resistant to at least one of the nine antimicrobials tested. Additionally, all isolates possessed the blaTEM-116 gene. The presence of this gene in V. parahaemolyticus indicates the possibility of spreading this gene in the environment. Atypical strains of V. parahaemolyticus were also detected in this study.

Cloning, expressing, and hemolysis of tdh, trh and tlh genes of Vibrio parahaemolyticus

Vibrio parahaemolyticus (VP) is one of the pathogenic vibrios endangering net-cage cultured Pseudosciaena crocea, Fennerpenaeus chinensis, and shellfish in coastal areas of China. Several types of hemolysins produced by Vp have been characterized as major virulence factors. They are thermostable direct hemolysin (TDH), TDH-related hemolysin (TRH) and thermolabile hemolysin (TLH). In this study, we cloned tdh, trh, and tlh genes from the genome DNA of VP by polymerase chain reaction (PCR). We ligated the three genes into prokaryotic expression vector pET-28a (+), and transformed the recombinant plasmids into Escherichia coli BL21 (DE3). The expression of recombinant proteins was induced by isopropyl-β-D-thiogalacto-pyranoside (IPTG). The recombinant proteins were expressed in a form of inclusion bodies and thus purified with Ni-NTA affinity chromatography. Western blotting results showed that recombinant proteins, TDH, TRH and TLH, could be recognized by rabbit anti-VP serum. The three purified proteins were renatured by gradient dialysis. The renatured proteins exhibited hemolytic activity except for TLH in the presence of phosphatidylcholine. These results not only are helpful for better understanding these genes’ functions under a single factor level, but also provide evidence for VP vaccine engineering.

Identification and expression analysis of the genes involved in serotonin biosynthesis and transduction in the field cricket Gryllus bimaculatus

Serotonin (5-HT) modulates various aspects of behaviours such as aggressive behaviour and circadian behaviour in the cricket. To elucidate the molecular basis of the cricket 5-HT system, we identified 5-HT-related genes in the field cricket Gryllus bimaculatus DeGeer. Complementary DNA of tryptophan hydroxylase and phenylalanine-tryptophan hydroxylase, which convert tryptophan into 5-hydroxy-L-tryptophan (5-HTP), and that of aromatic L-amino acid decarboxylase, which converts 5-HTP into 5-HT, were isolated from a cricket brain cDNA library. In addition, four 5-HT receptor genes (5-HT(1A) , 5-HT(1B) , 5-HT(2α) , and 5-HT(7) ) were identified. Expression analysis of the tryptophan hydroxylase gene TRH and phenylalanine-tryptophan hydroxylase gene TPH, which are selectively involved in neuronal and peripheral 5-HT synthesis in Drosophila, suggested that two 5-HT synthesis pathways co-exist in the cricket neuronal tissues. The four 5-HT receptor genes were expressed in various tissues at differential expression levels, suggesting that the 5-HT system is widely distributed in the cricket.

Rapid detection of Vibrio parahaemolyticus by PCR targeted to the histone-like nucleoid structure (H-NS) gene and its genetic characterization

The aim of this study was to explore a new PCR target gene for Vibrio parahaemolyticus, based on the histone-like nucleoid structure (H-NS) gene. Primers for the H-NS gene were designed for specificity to V. parahaemolyticus and incorporated into a PCR assay. The PCR assay was able to specifically detect all of the 82 V. parahaemolyticus strains tested, but did not result in amplification in the 47 other Vibrio spp. and nonVibrio spp. strains. The detection limit of the PCR assay was 0.14 pg purified genomic DNA and 1.8 × 10(5) CFU g(-1) spiked oyster samples from V. parahaemolyticus RIMD2210633. Furthermore, a multiplex PCR assay targeting the hns, tdh and trh genes was successfully developed to detect virulent V. parahaemolyticus strains. The H-NS-based PCR assay developed in this study was sensitive and specific, with great potential for field detection of V. parahaemolyticus in seawater or seafood samples. The H-NS gene was validated as a new specific marker gene in PCR assays for accurate detection and identification of V. parahaemolyticus, which has the potential to be applied in diagnostics and taxonomic studies.

Transcriptional profiling of fetal hypothalamic TRH neurons

BackgroundDuring murine hypothalamic development, different neuroendocrine cell phenotypes are generated in overlapping periods; this suggests that cell-type specific developmental programs operate to achieve complete maturation. A balance between programs that include cell proliferation, cell cycle withdrawal as well as epigenetic regulation of gene expression characterizes neurogenesis. Thyrotropin releasing hormone (TRH) is a peptide that regulates energy homeostasis and autonomic responses. To better understand the molecular mechanisms underlying TRH neuron development, we performed a genome wide study of its transcriptome during fetal hypothalamic development.ResultsIn primary cultures, TRH cells constitute 2% of the total fetal hypothalamic cell population. To purify these cells, we took advantage of the fact that the segment spanning -774 to +84 bp of the Trh gene regulatory region confers specific expression of the green fluorescent protein (GFP) in the TRH cells. Transfected TRH cells were purified by fluorescence activated cell sorting, various cell preparations pooled, and their transcriptome compared to that of GFP- hypothalamic cells. TRH cells undergoing the terminal phase of differentiation, expressed genes implicated in protein biosynthesis, intracellular signaling and transcriptional control. Among the transcription-associated transcripts, we identified the transcription factors Klf4, Klf10 and Atf3, which were previously uncharacterized within the hypothalamus.ConclusionTo our knowledge, this is one of the first reports identifying transcripts with a potentially important role during the development of a specific hypothalamic neuronal phenotype. This genome-scale study forms a rational foundation for identifying genes that might participate in the development and function of hypothalamic TRH neurons.

Creb and Sp/Krüppel response elements cooperate to control rat TRH gene transcription in response to cAMP

Expression of hypophysiotropic TRH, that controls thyroid axis activity, is increased by cold exposure; this effect is mimicked in rat hypothalamic cells incubated with norepinephrine or cAMP analogs. TRH proximal promoter contains three putative CRE: Site-4 or CRE-1 that overlaps an element recognized by thyroid hormone receptors, CRE-2 with adjacent sequences GC box or CACCC recognized by Sp/Krüppel factors (extended CRE-2), and AP-1 sites flanking a GRE 1/2. To evaluate the role of each element in the cAMP response, these sites were mutated or deleted in rat TRH promoter linked to luciferase gene (TRH-luc) and co-transfected with β-gal expression vector in various cell lines; C6 cells gave the highest response to forskolin. Basal activity was most affected by mutations or deletion of CRE-2 site, or CACCC (50–75% of wild type—WT). Forskolin-induced 3× stimulation in WT which decreased 25% with CRE-1 or AP-1 deletions, but 50% when CRE-2 or its 5′ adjacent GC box was altered. SH-SY5Y cells co-transfected with CREB-expression vector increased dB-cAMP response in the wild type but not in the CRE-2 mutated plasmid; cotransfecting CREB-A (a dominant negative expression vector) strongly diminished basal or cAMP response. Primary cultures of hypothalamic cells transfected with plasmids containing deletions of CRE-1, CRE-2, or extended CRE-2 failed to respond to forskolin when CRE-2 was modified. These results corroborate the CRE-2 site as the main cAMP-response element of rat TRH promoter, not exclusive of transcription factors of hypothalamic cells, and stress the relevance of adjacent Sp-1 sites, important mediators of some metabolic hormones.

Development of monoclonal antibody based sandwich ELISA for the rapid detection of pathogenic Vibrio parahaemolyticus in seafood

Thermostable direct hemolysin (TDH) and TDH-related hemolysin (TRH) are considered important virulence factors of Vibrio parahaemolyticus and strains producing either of these or both are considered pathogenic. In this study, we generated monoclonal antibodies (mAbs) against purified TRH recombinant protein of pathogenic V. parahaemolyticus. Sandwich enzyme-linked immunosorbent assays (ELISA) using the hybridoma clone 4B10 showed higher sensitivity of detection compared to other clones. Using mAb 4B10 based sandwich ELISA, we could detect pathogenic V. parahaemolyticus in 41.18% (14 out of 34) of the seafood samples analyzed. PCR targeting the toxR gene showed the presence of V. parahaemolyticus in 64.7% (22 out of 34) seafood samples. Further, PCR targeting the virulence genes showed that 6 seafood samples harboured the tdh gene while 9 harboured the trh gene indicating the presence of pathogenic V. parahaemolyticus. Our results show that mAb 4B10 sandwich ELISA developed in this study could be used as a rapid method for screening seafood samples for the presence of pathogenic V. parahaemolyticus.

Virulence and antimicrobial resistance characteristics of Vibrio parahaemolyticus isolated from environment, food and clinical samples in the south of Vietnam, 2010

Background Vibrio parahaemolyticus is a major cause of food poisoning in many countries. The rapid cases of this agent in recent years made it become an important etiology. However, the relationship between strains isolated from environment, food and clinical samples is still unclear. The presence of antimicrobial resistance and virulence factors such as tdh (thermostable direct hemolysin), trh (the TDH – related hemolysin) are proven to be candidate markers for studying on Vibrio parahaemolyticus. In Vietnam, the existence of Vibrio parahaemolyticus is poorly understood. Our objective was to analyse the presence of Vibrio parahaemolyticus from different sources of samples as well as its virulent factors (tdh and trh genes) and antibiotic resistance characteristics.

Antibiotic resistance of Vibrio parahaemolyticus isolated from pond-reared Litopenaeus vannamei marketed in natal, brazil.

Ten out of fifty fresh and refrigerated samples of shrimp (Litopenaeus vannamei) collected from retailers in Natal (Rio Grande do Norte, Northeastern Brazil) tested positive for Vibrio parahaemolyticus. The Kanagawa test and multiplex PCR assays were used to detect TDH and TRH hemolysins and the tdh, trh and tlh genes, respectively. All strains were Kanagawa-negative and tlh-positive. Antibiotic susceptibility testing was done for seven antibiotics by the agar diffusion technique. Five strains (50%) presented multiple antibiotic resistance to ampicillin (90%) and amikacin (60%), while two strains (20%) displayed intermediate-level resistance to amikacin. All strains were sensitive to chloramphenicol. Intermediate-level susceptibility and/or resistance to other antibiotics ranged from 10 to 90%, with emphasis on the observed growing intermediate-level resistance to ciprofloxacin. Half our isolates yielded a multiple antibiotic resistance index above 0.2 (range: 0.14–0.29), indicating a considerable risk of propagation of antibiotic resistance throughout the food chain.

The Krüppel-like factor 4 controls biosynthesis of thyrotropin-releasing hormone during hypothalamus development

Embryonic neurogenesis is controlled by the activation of specific genetic programs. In the hypothalamus, neuronal thyrotropin-releasing hormone (TRH) populations control important physiological process, including energy homeostasis and autonomic function; however, the genetic program leading to the TRH expression is poorly understood. Here, we show that the Klf4 gene, encoding the transcription factor Krüppel-like factor 4 (Klf4), was expressed in the rat hypothalamus during development and regulated Trh expression. In rat fetal hypothalamic cells Klf4 regulated Trh promoter activity through CACCC and GC motifs present on the Trh gene promoter. Accordingly, hypothalamic Trh expression was down-regulated at embryonic day 15 in the Klf4 −/− mice resulting in diminished bioactive peptide levels. Although at the neonatal stage the Trh transcript levels of the Klf4 −/− mice were normal, the reduction in peptide levels persisted. Thus, our data indicate that Klf4 plays a key role in the maturation of TRH expression in hypothalamic neurons.

Evaluation of the virulence of Vibrio parahaemolyticus strains isolated in Russia and contiguous states

One hundred and ninety-six Vibrio parahaemolyticus strains that are etiological agents causing outbreaks and sporadic cases of food toxicoinfections and isolated from the environments of Russia, Ukraine, and Turkmenia are characterized by virulence-associated phenotypic and genotypic signs. Most clinical strains were found to contain the genes of the major pathogenicity factors - thermostable direct hemolysin (TDH) and/or TDH-related hemolysin (TRH); however, a large number of pathogens lack these genes. In all likelihood, these strains can cause human diseases, by producing other toxic substances. The presence of the trh gene correlated with that and expression of the urease genes. Comparative analysis of the findings has demonstrated that the results of polymerase chain reaction detection of the tdh gene do not always agree with the signs of hemolytic activity on the Wagatsum medium (Kanagawa phenomenon). Therefore, both tests that complement each other are recommended for a fuller evaluation of the potential danger of Vibrio parahaemolyticus strains.

Molecular cloning, gene structure, molecular evolution and expression analyses of thyrotropin-releasing hormone receptors from medaka ( Oryzias latipes)

Molecular cloning of thyrotropin-releasing hormone receptors (TRHR) was performed in a model teleost fish, medaka ( Oryzias latipes). Four subtypes of TRHR were cloned and named them as TRHR1a, TRHR1b, TRHR2 and TRHR3 based on their similarity to known TRHR subtypes in vertebrates. TRHR1a, TRHR1b, TRHR2, and TRHR3 of medaka encode 416, 398, 451, and 386 amino acid residues, respectively. Comparison of cDNA sequences of medaka TRHR subtypes with respective genomic DNA sequences revealed gene structures: TRHR1a, TRHR1b and TRHR3 genes consist of two exons while the TRH2 gene consists of five exons. Molecular phylogenetic analyses depicted the molecular evolution of TRHR in vertebrates: From the ancestral molecule, TRHR2 diverged first and then TRHR1 and TRHR3. Reverse transcription-polymerase chain reaction analyses revealed the sites of TRHR expression: Expression of TRHR1, TRHR1b and TRHR2 subtypes has been confirmed in the brain, pineal organ, retina and pituitary gland. In addition, TRHR1b is expressed in spleen, digestive tract and skin, and TRHR2 in testis, ovary and gill. TRHR3 is widely expressed in various tissues. These results indicate that in medaka, TRH might exert multiple functions mediated by different TRHR subtypes expressed in each tissue.

Regulation of Thyrotropin-Releasing Hormone-Expressing Neurons in Paraventricular Nucleus of the Hypothalamus by Signals of Adiposity

Fasting-induced suppression of thyroid hormone levels is an adaptive response to reduce energy expenditure in both humans and mice. This suppression is mediated by the hypothalamic-pituitary-thyroid axis through a reduction in TRH levels expressed in neurons of the paraventricular nucleus of the hypothalamus (PVN). TRH gene expression is positively regulated by leptin. Whereas decreased leptin levels during fasting lead to a reduction in TRH gene expression, the mechanisms underlying this process are still unclear. Indeed, evidence exists that TRH neurons in the PVN are targeted by leptin indirectly via the arcuate nucleus, whereas correlative evidence for a direct action exists as well. Here we provide both in vivo and in vitro evidence that the activity of hypothalamic-pituitary-thyroid axis is regulated by both direct and indirect leptin regulation. We show that both leptin and α-MSH induce significant neuronal activity mediated through a postsynaptic mechanism in TRH-expressing neurons of PVN. Furthermore, we provide in vivo evidence indicating the contribution of each pathway in maintaining serum levels of thyroid hormone.

Occurrence of ToxigenicVibrio parahaemolyticusStrains in Shrimp in Iran

Vibrio parahaemolyticus, a common cause of foodborne gastroenteritis in people, is frequently isolated from a variety of seafood, including shrimp. The virulence of clinical V. parahaemolyticus strains is commonly associated with expression of thermostable direct hemolysin (TDH) and TDH-related hemolysin (TRH), which are encoded by the tdh and trh genes. This study was conducted to determine the prevalence rate of total and toxigenic V. parahaemolyticus in shrimp caught off the south coast of Iran. Three hundred freshly caught shrimp from four different species, Penaeus monodon, Penaeus semisulcatus, Penaeus indicus, and Penaeus merguiensis, were collected in three provinces along Persian Gulf in the south coast of Iran. Shrimp were collected at the end of each month from July 2008 to July 2009. The samples were analyzed for the presence of V. parahaemolyticus and the occurrence of toxigenic strains. Using conventional bacteriological techniques, 29 V. parahaemolyticus isolates were identified in which 28 strains were confirmed by a polymerase chain reaction assay targeting the tlh gene of V. parahaemolyticus. Using polymerase chain reaction assays targeting the tdh and trh genes, five (1.7%) and two (0.7%) isolates were tdh positive and trh positive, respectively. The tdh-positive isolates were commonly detected in summer, whereas no toxigenic strain was isolated in winter. To the best of our knowledge, the present study is the first report of the presence of toxigenic tdh- and trh-positive V. parahaemolyticus strains in the seafood in Iran.

Distribution of type III secretion systems in Vibrio parahaemolyticus from the northern Gulf of Mexico

Two well-characterized Vibrio parahaemolyticus pathogenicity factors - thermostable direct haemolysin (TDH) and TDH-related haemolysin - are produced by strains containing the tdh and trh genes, respectively. Most strains of V. parahaemolyticus contain two nonredundant type III secretion systems (T3SS), T3SS1 and T3SS2, both of which contribute to pathogenicity. Furthermore, a recent study has revealed two distinct lineages of the V. parahaemolyticus T3SS2: T3SS2α and T3SS2β. The aim of this study was to determine the incidence of these pathogenicity factors in environmental isolates of V. parahaemolyticus. We collected 130 V. parahaemolyticus isolates (TCBS agar) containing tdh and/or trh (determined by colony hybridization) from sediment, oyster and water in the northern Gulf of Mexico and screened them and 12 clinical isolates (PCR and agarose gel electrophoresis) for pathogenicity factors tdh, trh, T3SS1, T3SS2α and T3SS2β. The majority of potential pathogens were detected in the sediment, including all tdh(-) /trh(+) isolates. T3SS2α components were detected in all tdh(+) /trh(-) isolates and zero of 109 trh(+) isolates. One T3SS2α gene, vopB2, was found in all tdh(+) /trh(-) clinical strains but not in any of the 130 environmental strains. Fluorescence in situ hybridization adapted for individual gene recognition (RING-FISH) was used to confirm the presence/absence of vopB2. T3SS2β was found in all tdh(-) /trh(+) isolates and in no tdh(+) /trh(-) isolates. The combination of haemolysins found in each isolate consistently corresponded to the presence and type of T3SS detected. The vopB2 gene may represent a novel marker for identifying increased virulence among strains. This is the first study to confirm the presence of T3SS2β genes in V. parahaemolyticus strains isolated from the Gulf of Mexico and one of the few that examines the distribution and co-existence of tdh, trh, T3SS1, T3SS2α and T3SS2β in a large collection of environmental strains.

Molecular characterizations of pathogenic Vibrio parahaemolyticus isolated from Southern Taiwan oyster-growing environment

Ninety-four virulent strains of Vibrio parahaemolyticus containing tdh and/or trh genes isolated from seawater, sediment, and oysters collected in Penghu, Tainan, and Changhua Lukang coastal water were characterized by analyses of O-group antigens, pulsed-field gel electrophoresis (PFGE) after digestion with SfiI enzyme, and randomly amplified polymorphic DNAs (RAPD). Analysis of virulence markers ( tdh and trh) revealed that 60.6% of the isolates possessed only tdh, 13.8% of them possessed only trh, and 25.5% of them possessed both tdh and trh. Ten O-group serotypes (O1, O2, O3, O4, O5, O6, O7, O8, O10, and O11) were identified among the isolates with O1 group (28 isolates) being the most prevalent, followed by the O3 group (16 isolates) and O5 group (15 isolates). PFGE typing of the isolates revealed 94 patterns while RAPD analyses categorized the isolates into five major groups. Both PFGE and RAPD analyses showed high index of discrimination ( DI) values. This study identified diverse serotypes and genotypes of virulent V. parahaemolyticus distributed in the oyster-growing environments, which can be used for risk assessment of V. parahaemolyticus infection associated with oyster consumption in Taiwan.

Distribution of Genes Encoding Four Pathogenicity Islands (VPaIs), T6SS, Biofilm, and Type I Pilus in Food and Clinical Strains ofVibrio parahaemolyticusin China

Vibrio parahaemolyticus is a major cause of foodborne gastroenteritis in China, Japan, and other countries. The pandemic O3:K6 clone, which harbors thermostable direct hemolysin [tdh] gene and toxRS/new gene, is mainly responsible for the foodborne outbreaks after 1995. Previous studies showed that genes in the pathogenicity island-1 (VPaI-1) and VPaI-5 are harbored only by pandemic strains, whereas genes in VPaI-7 and type III secretion system 2 are closely associated with tdh-positive strains of V. parahaemolyticus. In this study, we examined the distribution of genes encoding VPaI-2, VPaI-3, VPaI-4, VPaI-6, type VI secretion systems (T6SS), biofilm, and type I pilus in 71 food and 116 clinical strains of V. parahaemolyticus. The results showed that most of the pandemic strains of V. parahaemolyticus harbored the complete genes of VPaI-2, T6SS, and type I pilus. In contrast, most of the pathogenic strains (harboring tdh gene or TDH-related hemolysin [trh] gene) and nonpathogenic strains (harboring neither tdh gene nor trh gene) contained partial genes of VPaI-2, T6SS, and type I pilus. Genes of VPaI-4 were exclusively present in the pandemic strains. Genes of VPaI-3 were present in most of the pandemic strains and a small percentage of nonpathogenic strains, mainly O3:K6 strains. VPaI-6 and biofilm-associated genes were harbored by almost all the strains, irrespective of their pandemic, pathogenic, or nonpathogenic traits.