Apoptosis, inflammatory and innate immune responses induced by infection with a novel goose astrovirus in goose embryonic kidney cells

IntroductionSince 2016, a highly lethal visceral gout induced by infection with the novel goose astrovirus (GoAstV) resulted in an ongoing outbreak in goslings in China, with a mortality rate ranging from 10% to 50%, and causing considerable economic losses in the goose industry. However, the pathogenesis of GoAstV and the molecular mechanism by which kidney lesions are induced by GoAstV infection are unclear.MethodsIn the present study, a GEK cell infection model for GoAstV was established, and the apoptosis, inflammatory and innate immune responses induced by GoAstV were investigated in GEK cells.ResultsThe results shown that the expression of proapoptotic proteins, including Bax, caspase-3, caspase-9 and cytochrome c, increased in the infection group; however, the expression of the antiapoptotic protein Bcl-2 decreased, indicating that apoptosis was induced by GoAstV infection in GEK cells. Besides, the activation of the RIG-I/MDA5 pathway and the downstream upregulation of proinflammatory cytokines, including the adapter proteins MAVS, IRF7 and NF-κB and the proinflammatory cytokines IL-6, IL-8 and TNF-α, were detected in GEK cells infected with GoAstV. In addition, GoAstV infection induces the activation of the NLPR3 pathway and further stimulates the increased production of IL-1β. In summary, the present study revealed that GoAstV infection could induce apoptosis and the activation of the RIG-I/MDA5 and NLRP3 pathways in GEK cells, as well as the massive release of proinflammatory cytokines.DiscussionThese results are helpful for elucidating the molecular mechanism of pathological lesions in the kidney in gout goslings infected with GoAstV and the interaction between GoAstV and the innate immune system of the host.