BACKGROUND V. 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. RESULTS Twenty-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. CONCLUSION Our 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.

中文翻译：

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从印度海岸分离的副溶血性弧菌的遗传和毒力表征。

背景技术副溶血性弧菌对海洋环境是自生的，并在人类中引起海鲜传播的肠胃炎。通常，从环境和/或海鲜中回收的副溶血性弧菌被认为是非致病性的，人们对环境分离物与急性腹泻病之间的关系了解甚少。在这项研究中，我们探讨了从印度海岸采集的水，浮游生物和各种海鲜样品中分离到的副溶血性弧菌的潜在毒性。结果从海鲜中检出的22株副溶血弧菌带有毒力相关基因，这些基因编码热稳定直接溶血素（TDH），TDH相关溶血素（TRH）和3型分泌系统（T3SS），其中95.5％的产毒菌株具有大流行株属性（toxRS / new +）。九个血清型，新近鉴定出具有大流行毒株性状和O4：K36 tdh-trh + V。首次发现带有副溶血性大流行标记基因。通过逆转录PCR获得的结果显示，trh，T3SS1和T3SS2β在海鲜分离物中起作用。此外，环境菌株具有细胞毒性，在感染后可侵袭Caco-2细胞，并诱导紧密连接蛋白，ZO-1和肌动蛋白细胞骨架发生变化。结论我们的研究提供了证据，证明副溶血性弧菌的环境分离物具有潜在的侵入性，并能够引起临床菌株典型的致病特征，并存在潜在的健康风险。