IFNA1 and infection: Although we had a particular interest in type I IFN response of pigs in the mutant PRRSV-infected groups, PRRSV-2 suppresses IFN response at an early stage of infection, and shortly after, IFNs are bounced back to 20, normal and increased by 3–4 days of infection, which led us to ignore the type I IFN measurements in the present study.