Mammalian retinoic acid-inducible gene I (RIG-I) is a chief antiviral gene sensing viral RNA molecules including Newcastle disease virus (NDV). In this study, goose RIG-I gene (gRIG-I) was identified. The 2805 bp-long gene encodes a gRIG-I protein that exhibits 93.8% amino acid identity to duck RIG-I. DF-1 chicken fibroblast cells transfected with full-length of gRIG-I or CARD domain of gRIG-I plasmids respond significantly to the agonist of 21-mer 5'ppp RNA, evident through enhancement of IFN-β promoter activity. Goose RIG-I transfected 293T/17 cells were then tested for the response to NDV infection, resulting in up-regulated activity of IFN-β promoter, and mRNA levels of IRF-3 and IFIT1, but decreased virus titer. Similar results were obtained in transfected DF-1 chicken fibroblast cells and goose embryo fibroblast cells in response to NDV infections Animal experiments further support a role of gRIG-I in goose innate immunity against NDV infections by showing increased gRIG-I mRNA levels and decreased virus titer in geese lung and air sac post-infection.
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