ISG15 and viral infectious disease: Of the top 20 upregulated genes upon viral infection (IAV or SARS-CoV2), in both ALI tissues, 11/20 genes were shared (IFI27, ISG15, IFI6, IFIT1, BST2, IFIT2, IFIT3, CXCL10, MX1, OAS1, and IFI44L), with a primary function as defense response to viral infection (DAVID Analysis, GOTERM_BP_DIRECT, GO:0051607: defense response to virus, 10/11 genes, p value 2.9e-17).