Infection at an MOI of 1 resulted in few to no infected cells at 6 hpi; however, at an MOI of 10, where most of the cells were infected (Fig. 4K), we observed a reduced level of phosphorylated IRF3 in PR1NS53UTR compared with PR1 (Fig. 4J), indicating early inhibition of the type I IFN response. Here, IRF3 is linked to infection.