IRF1 and viral infectious disease: In the present study, overexpression of IRF1 in KO IRF7 cells did not restore the IFN-β expression, whereas overexpression of IRF1 in KO IFNAR1 in the presence of IRF7 increased the IFN-β expression at the later stage of viral infection, supporting the dominant role of IFN-β induction by IRF1 in DTMUV-infected DF1 cells.