USP18 and viral infectious disease: Most of the upregulated genes in the high viral load group are involved in the immune response during viral infection, specifically, genes involved in interferon alpha/beta signaling (IFITM3, IFITM1, RSAD2, MX2, IFI6, ISG15, IFI35, IFIT1, USP18, OASL, BST2, ISG20, OAS1, OAS2, OAS3, IRF7, and XAF1) (Fig. 2A and B) and immunoregulatory interactions between a lymphoid and a nonlymphoid cell (IFITM1, CD300E, LILRB1, and SIGLEC1) (Fig. 2B).