Avian infectious bronchitis virus disrupts the melanoma differentiation associated gene 5 (MDA5) signaling pathway by cleavage of the adaptor protein MAVS

Yu, Liping; Zhang, Xiaorong; Wu, Tianqi; Su, Jin; Wang, Yuyang; Wang, Yuexin; Ruan, Baoyang; Niu, Xiaosai; Wu, Yantao

MDA5 and RIG-I are the two major PRRs for detecting RNA viruses. They can both detect RNA viruses and activate a signaling pathway that leads to the production of type I interferon and the initiation of antiviral activities [17, 37] . Considerable attention has recently been given to the role of chMDA5 in IBV infections in chickens, which appear to lack RIG-I [34] . Our results confirm the findings that chMDA5 is the receptor that mediates the antiviral response to IBV infection. Upregulation of chIFN-β following IBV infection in chMDA5-overexpression cells suggests that chMDA5 interacts with the proteins induced by IBV infection [25] . The silencing of chMDA5 expression resulted in a reduction of IBV-induced chIFN-β transcription and highlights the role that chMDA5 may play in antiviral defense. The absence of RIG-I in chickens may lead to insufficient antiviral responses to IBV infections, resulting in only chickens being susceptible to IBV infections, whereas ducks and geese, which possess RIG-I, are not infected with IBV [38] . chIFN-β was upregulated in response to IBV infection in dgRIG-I-overexpressed chicken cells, which is similar to observations made in mammalian models [23, 38] . Our study implies that dgRIG-I plays a similar role as chMDA5 in IBV-infected chicken cells, inducing the interferon response.