IFNB1 and infection: Quantification of relative mRNA induction over the first 24 h after infection with an MOI of 1 revealed a gradual increase of 2′-5′-oligoadenylate synthase 3, the upstream activator of RNase L, IFN-β, and the IFN-stimulated gene Mx1 (Fig. 6C to E), which mirrored the increase in MeV N mRNA levels over the same period (Fig. 6A).