Aeromonas veronii is one of the main pathogens causing sepsis and ulcer syndrome in freshwater fish. Analysis of the results of epidemiological investigations in recent years has revealed that the virulence of A. veronii and its tolerance to drugs have been increasing year by year. Currently, most of the research on A. veronii focuses on its isolation, identification, and drug susceptibility, whereas research on its virulence factors and pathogenesis mechanisms is relatively rare. In this study, we identified and obtained the highly expressed TH0426 cadaverine reverse transporter (CadB) of A. veronii. We used efficient suicide plasmid-mediated homologous recombination to delete the cadB gene in TH0426 and constructed a cadB deletion strain. The LD50 of ΔcadB was 93.2 times higher than that of TH0426 in zebrafish, the toxicity of ΔcadB was 9.5 times less than that of TH0426 in EPC cells, and the biofilm formation ability of ΔcadB was 5.6-fold greater than that of TH0426. In addition, motility detection results indicated that ΔcadB had lost its swimming ability. The results of flagellar staining and TEM demonstrated that ΔcadB shed the flagella. In summary, the virulence and adhesion of A. veronii TH0426 were significantly decreased by the deletion of cadB, which might provide a theoretical basis for research into A. veronii virulence factors.

中文翻译：

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尸胺反向转运蛋白（CadB蛋白）有助于维罗纳气单胞菌TH0426的毒性。

Veronii气单胞菌是引起淡水鱼败血症和溃疡综合症的主要病原体之一。近年来对流行病学调查结果的分析表明，维罗氏假单胞菌的毒力及其对药物的耐受性逐年增加。目前，对Ver.ii的大多数研究都集中在其分离，鉴定和药物敏感性上，而对它的毒力因子和发病机理的研究则相对较少。在这项研究中，我们鉴定并获得了高表达的拟南芥TH0426尸胺反向转运蛋白（CadB）。我们使用有效的自杀质粒介导的同源重组删除TH0426中的cadB基因，并构建了cadB删除菌株。在斑马鱼中，ΔcadB的LD50是TH0426的93.2倍，ΔcadB的毒性是9。在EPC细胞中，其比TH0426小5倍，并且ΔcadB的生物膜形成能力是TH0426的5.6倍。另外，运动性检测结果表明ΔcadB丧失了游泳能力。鞭毛染色和透射电镜的结果表明，ΔcadB脱落了鞭毛。综上所述，cadB的缺失显着降低了Ver。a。veronii TH0426的毒力和粘附力，这可能为研究A. veronii毒力因子提供理论依据。