Interestingly, even in MEFs or MEF PKR-/-, MYXV or M029-minus virus infection can still efficiently inhibit mouse type I IFN-induced signaling provided the IFN is added at least 6 h after the viral infection, suggesting that the induced viral protein(s) are involved in blocking IFN signaling downstream of the IFN receptor. Here, IFNA1 is linked to viral infectious disease.