Li Sen, Wang Yanhua, Ning Congran, Yang Rongkun, Wu Yaxin, Cheng Xu, Ren Keke, Huang Minghua, Liu Xiong, Zhou Naiji, Zhang Wanpo, Hu Sishun, Xiao Yuncai, Li Zili, Zhou Hongbo, Liu Zhengfei, Zhou Zutao
College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.
Vet Res. 2025 Jun 8;56(1):112. doi: 10.1186/s13567-025-01550-8.
Riemerella anatipestifer infection is a critical disease that is a major threat to the poultry industry worldwide. The adhesion and invasion of host cells are key steps in the primary stages of bacterial infection. However, the outer membrane proteins that mediate these events in R. anatipestifer are poorly characterized. In this study, the PorV and PosF proteins, as well as the previously described OMP71 protein, were identified as important mediators of the adhesion and invasion of duck embryo fibroblast (DEF) cells by R. anatipestifer. Affinity chromatography-based surface proteomics was used to screen for adhesion proteins. The surface proteins on DEF cells were labelled with biotin-avidin to enrich for outer membrane proteins of R. anatipestifer, which generated 11 candidate proteins that were tested further. Protein adhesion and blocking assays and polyclonal antiserum inhibition analysis revealed that the PorV, PosF, and OMP71 proteins are adhesion factors. Knockout of porV or posF reduced the adhesion and invasion of R. anatipestifer in DEF cells. Moreover, the pathogenicity of the mutant strains was significantly attenuated, which supports the hypothesis that PorV and PosF are important virulence factors required for the pathogenicity of R. anatipestifer. The PorV protein is a key component of the type IX secretory system and is responsible for transporting effector substrates to the extracellular environment, whereas PosF belongs to the porin superfamily of barrel-shaped transmembrane proteins. This is the first description that PorV is an adhesin involved in host‒microbial interactions, which represents a breakthrough in pathogenicity studies of R. anatipestifer and other members of Flavobacteriaceae.
鸭疫里默氏菌感染是一种严重疾病，对全球家禽业构成重大威胁。宿主细胞的黏附和侵袭是细菌感染初期的关键步骤。然而，介导鸭疫里默氏菌这些过程的外膜蛋白特性尚不明确。在本研究中，PorV和PosF蛋白以及先前描述的OMP71蛋白被确定为鸭疫里默氏菌黏附和侵袭鸭胚成纤维细胞（DEF）的重要介质。基于亲和层析的表面蛋白质组学用于筛选黏附蛋白。用生物素-抗生物素蛋白标记DEF细胞上的表面蛋白，以富集鸭疫里默氏菌的外膜蛋白，从而产生11种待进一步测试的候选蛋白。蛋白质黏附与阻断试验以及多克隆抗血清抑制分析表明，PorV、PosF和OMP71蛋白是黏附因子。敲除porV或posF可降低鸭疫里默氏菌在DEF细胞中的黏附和侵袭。此外，突变菌株的致病性显著减弱，这支持了PorV和PosF是鸭疫里默氏菌致病性所需的重要毒力因子这一假说。PorV蛋白是IX型分泌系统的关键组分，负责将效应子底物转运到细胞外环境，而PosF属于桶状跨膜蛋白的孔蛋白超家族。这是首次描述PorV是一种参与宿主-微生物相互作用的黏附素，这代表了鸭疫里默氏菌及黄杆菌科其他成员致病性研究的一项突破。
