IRF3 and infection: Although infection with a virus that expresses an NS1 protein with the ESEV PBM activates IRF3 (Fig. 8A, 8C), induction of IRF3-regulated genes such as IFN-β is unlikely to occur due to viral functions that antagonize the IFN-β response downstream of IRF3 activation, especially the inhibition of IFN-β mRNA 3′ end processing by the interaction between NS1 and CPSF30.