Transfection of pigeon CARDs into chicken DF-1 cells enhanced the production of IFN-β without infection; however, pRIG-I was not as effective as pCARDs in inducing IFN due to its autorepression by CARDs and the HEL2i interaction when no RNA ligand is present to bind with the C-terminal domain. This evidence concerns the gene IFNA1 and infection.