IFNB1 and infection: At least two structural proteins (M and N proteins) and four nonstructural proteins of PRRSV, nsp1, nsp2, nsp11, and nsp4, have been identified as exhibiting inhibitory effects on IFN-β promoter activation, with nsp1 showing the strongest inhibitory effect and self-cleavage of nsp1 during infection to produce NSP1α and NSP1β.