In particular, SARS-CoV-2 infection could be driven by APOE, APP, BIN1, PSEN1/2, CD33, and TREM2; EBV infection is associated with SPI1, INPP5D, and MEF2C; HIV infection is linked to APOE and TREM2; HCV infection is correlated with BIN1, INPP5D, and CD2AP; and HSV-1 infection has associations with APOE, APP, PILRA, CLU, and PICALM. However, different genes may respond differently to a single viral infection, and some genes may act differently at different stages of infection. This evidence concerns the gene APOE and infection.