IRF3 and infection: To further validate these findings, we knocked down Usp8 in Usp8fl/fl mouse embryonic fibroblast (MEF) cells via infection with Cre lentivirus and found that the EMCV‐induced expression of Ifnb1 and Cxcl10 and the EMCV‐induced phosphorylation of TBK1 and IRF3 were significantly impaired (Figure 2H–J).