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Abstract：
Edwardsiella ictaluri is a Gram-negative intracellular facultative pathogen causing enteric septicemia of channel catfish (ESC). The Tol system, consisting of four envelope proteins TolQ, TolR, TolA, and TolB, are required for colicin import and contributes to bacterial virulence in several pathogenic bacteria. However, the Tol system and its importance in E. ictaluri virulence have not been investigated. Here we present construction and evaluation of the E. ictaluri TolQ, TolR and TolQR mutants (EiΔtolQ, EiΔtolR, and EiΔtolQR). The Tol mutants were developed using in-frame gene deletion and their attenuation and vaccine efficacy were determined in catfish fingerlings. The EiΔtolQ, EiΔtolR, and EiΔtolQR mutants showed reduced virulence in catfish (28.93%, 19.70%, and 39.82% mortality, respectively) compared to wild type (46.91% mortality). Further, vaccination with these mutants protected catfish against subsequent wild-type infection. This study suggests that the Tol system contributes to E. ictaluri virulence in catfish.
摘要：
Edwardsiellaictaluri是一种革兰氏阴性细胞内兼性病原体，可引起channel鱼（ESC）的肠败血症。Tol系统,由四种包膜蛋白TolQ组成，TolR,托拉,还有TolB,是大肠杆菌素进口所必需的，并有助于几种致病菌的细菌毒力。然而,Tol系统及其在伊氏大肠杆菌毒力中的重要性尚未得到研究。在这里，我们介绍了伊塔乌里托尔Q的构建和评估，TolR和TolQR突变体(EiΔtolQ，EΔtolR，和EiΔtolQR)。使用框内基因缺失开发了Tol突变体，并在cat鱼种中确定了它们的减毒和疫苗功效。EΔtolQ，EΔtolR，和EiΔtolQR突变体在鲶鱼中显示出降低的毒力(28.93%，19.70%,和39.82%的死亡率，分别)与野生型(46.91%死亡率)相比。Further,用这些突变体接种疫苗可以保护鲶鱼免受随后的野生型感染。这项研究表明，Tol系统有助于the鱼的E.ictaluri毒力。
