Gleasserella parasuis autotransporter Apd interacts with host vimentin to facilitate bacterial adhesion and systemic infection.

Gleasserella parasuis is a commercial importance pathogen that colonizes the upper respiratory tract of pigs. It has the capacity to invade the body and cause systemic infections in immunocompromised individuals. However, the interactions between G. parasuis proteins and host molecules during colonization and invasion remain unclear. In the present study, we identified an interaction between the autotransporter Apd of G. parasuis and the vimentin protein in swine macrophages through co-immunoprecipitation and mass spectrometry analyses. We confirmed that this interaction also occurs in swine serum. Furthermore, the interaction of Apd with vimentin enhances the adhesion and invasion of G. parasuis in swine macrophages. A swine challenge experiment using Δapd and wild-type strains demonstrated that the interaction between Apd and vimentin increases the virulence and systemic infection of G. parasuis. Thus, we conclude that the interaction between Apd and vimentin takes place during various stages, including bacterial adhesion, invasion, and infection. Further investigation of the interaction between Apd and vimentin will contribute to elucidating the molecular mechanisms underlying infection, immunity, and pathogenesis of G. parasuis.