To further identify the specific IRG that inhibits M1 viral infection, we used siRNAs to knock down the five genes identified above in the HCT‐15 cell line, including CDKN1A, IFI27, IFIT3, MX2, and ID1. The siRNA effectively knocked down the expression of these genes (Fig. S3), and only the knockdown of CDKN1A significantly increased the infection of M1 virus (Fig. 4A), indicating that CDKN1A might be a key factor. This evidence concerns the gene CDKN1A and viral infectious disease.