Cheng Zhao, Zhao Xianliang, Jiang Xinyu, Zhang Jie, Li Li, Pei Chao, Zhou Yong, Zeng Lingbing, Kong Xianghui
Engineering Lab of Henan Province for Aquatic Animal Disease Control, College of Fisheries, Henan Normal University, Xinxiang, Henan, China.
Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan, Hubei, China.
J Fish Dis. 2023 Mar;46(3):247-259. doi: 10.1111/jfd.13739. Epub 2022 Dec 14.
Aeromonas veronii is an important zoonotic and aquatic pathogen that causes a number of illnesses in both humans and animals. It is related to gastroenteritis, skin and soft tissue infections and bacteremia in humans, as well as causing significant economic losses in aquaculture owing to fish sepsis. Here, we constructed the flagellar cap gene (fliD) mutant strain of A. veronii by suicide plasmid-mediated homologous recombination system and analysed its characteristics. It was found that the deletion of fliD had no effect on growth and biochemical properties and could be inherited stably. However, the motility of A. veronii ΔfliD was significantly reduced, the flagellum was defective and the biofilm formation was attenuated compared with that of A. veronii wild-type strain. In vivo experiments revealed that the colonization capacity of ΔfliD was significantly lower than that of the wild-type strain in the period of first 24 h, and the median lethal dose (LD ) was 56 times higher than that of the wild-type strain. The Cyprinus carpio infected with the wild-type strain indicated faster death speed and more severe clinical signs compared to ΔfliD strain. These results suggest that fliD is closely related to the virulence of A. veronii and plays an important role in pathogenicity, providing the foundation for pathogenic mechanism studies of A. veronii.
维氏气单胞菌是一种重要的人畜共患病原体和水生病原体，可导致人类和动物多种疾病。它与人类的肠胃炎、皮肤和软组织感染以及菌血症有关，还会因鱼类败血症给水产养殖业造成重大经济损失。在此，我们通过自杀质粒介导的同源重组系统构建了维氏气单胞菌的鞭毛帽基因（fliD）突变株并分析其特性。结果发现，fliD的缺失对生长和生化特性没有影响，且能稳定遗传。然而，与维氏气单胞菌野生型菌株相比，维氏气单胞菌ΔfliD的运动性显著降低，鞭毛有缺陷，生物膜形成减弱。体内实验表明，在最初24小时内，ΔfliD的定殖能力显著低于野生型菌株，半数致死剂量（LD）比野生型菌株高56倍。与ΔfliD菌株相比，感染野生型菌株的鲤鱼死亡速度更快，临床症状更严重。这些结果表明，fliD与维氏气单胞菌的毒力密切相关，在致病性中起重要作用，为维氏气单胞菌致病机制研究奠定了基础。
