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

In ovo and in vitro study, we show that infection with IBV leads to a considerable activation of the type I IFN and antiviral immune response [33] . Among birds, the RIG-I and MDA5 genes are present in ducks, geese and pigeons, but only MDA5 gene can be identified in chickens [34] . RIG-I and MDA5 share a similar homology in their overall primary structure and induce the downstream signaling pathway involving MAVS [7, 11, 12] . In this study, to investigate the effect of dgRIG-I in the chicken immune system response to IBV infection, we identified and cloned dgRIG-I. We found that dgRIG-I plays a similar role to chMDA5 in upregulating the transcription of chIFN-β in response to IBV infection. It has been previously demonstrated that IBV can delay the transcription of chIFN-β in the early stages of infection [35] . In this study, we found that through the cleavage of the chMAVS protein, IBV can downregulate chIFN-β transcription, and the knockdown of chMAVS had a dramatic effect on chIFN-β activation, indicating a more predominant role of MAVS in the innate immune response against IBV infection.