IRF3 and infection: We performed western blot analysis of ECTV-infected L929, NIH3T3, and RAW264.7 cells, and found that the ECTV infection triggered Tbk1 and Irf3 phosphorylation in RAW264.7 and L929 cells, which reached peaks at 18 hpi (Figures S3A,B in Supplementary Material), whereas it failed to do so in NIH3T3 cells (Figure S3C in Supplementary Material), indicating that ECTV induced the levels of phosphorylation of Tbk1 and Irf3 in L929 and RAW264.7 cells in a cell type-dependent manner (15, 45).