USP18 and infection: In this experiment, significant induction of IFNB and IFNL1 occurred in response to both PIV3 and IAV, but not SARS-CoV-2, at 24 hpi (Supplementary Fig. 7), and was accompanied by upregulation of ISGs USP18 and RSAD2. Infection of cell lines at high MOI are reported to enhance the relatively inefficient IFN-I induction to SARS-CoV-225.