ISG15 and bacterial infectious disease: Ten hub genes were obtained using the PPI network and Cytoscape platform: RSAD2, IFIT3, GBP1, RTP4, IFI44, OAS1, IFI44L, ISG15, HERC5, and IFIT5, which were analyzed by Metascape platform and found to be associated with IFN signaling regulation and immune system response to viral infection and bacterial infection and were closely related.