To further investigate this possibility, we measured the induction of IFN-β over the first 24 h after infection of VHS and G4 cells with the mutant PPRVs (MOI = 1); this was done by measuring IFN-β promoter activation using reporter assays and levels of IFN-β mRNA using RT-qPCR, as described for previous experiments. Here, IFNB1 is linked to infection.