The role of GtxA during Gallibacterium anatis infection of primary chicken oviduct epithelial cells

Abstract Gallibacterium anatis (G. anatis), one of the major pathogens causing reproductive tract disorders in laying hens, leads to egg production and increased mortality, either single or mixed infections with other diseases. As a specific virulence factor of G. anatis, the role of GtxA in layers’ salpingitis remains unclear. In this study, we explored the effect of GtxA on G. anatis infection by comparing wild strain Yu-PDS-RZ-1-SLG (RZ) and its GtxA deleted counterpart RZΔgtxA in primary chicken oviduct epithelial cells (COEC). Their adherence, invasion, cytotoxicity, inducing apoptosis and cytokine secretion were evaluated and the cytotoxicity and cytokine secretion of the recombinant GtxA protein and its structural domain were also analyzed. We found that the adhesion ability of RZΔgtxA was significantly lower than that of parental strain RZ, and its toxicity to COEC was weakened; Meanwhile, apoptosis was inhibited and the expression of IL-6, IL-2, TNF-α and IFN-γ were dramatically reduced in COEC infected by RZΔgtxA. In contrast, the recombinant protein GtxA inhibited the proliferation of oviduct cells and induced obvious cytotoxicity, and the expression of IL-6, TNF-α and IFN-γ were up-regulated in COEC interacted with recombinant proteins. Our study indicates that GtxA promotes G. anatis adhere to cells, changes cells permeability and expression of inflammatory factors, resulting in cell damage and apoptosis.