Figure 3

SARS-CoV-2 activates type I and III IFN responses via MDA5 and IRF3, and inhibits ISG induction in infected Calu-3 cells. (A) Calu-3 cells were depleted of MAVS, STING, IRF3, MDA5 or RIG-I using a lenti-CRISPR approach. Depletion of the targeted proteins was assessed by western blot. Control cells were targeted for GFP, which is absent in Calu-3 cells. See Supplementary Figure 4 for full blots. (B) Cells from (A) were infected and analysed as described in Fig. 2C. (C–F) Cells from (A) were infected as in Fig. 2C, stained for live cells, SARS-CoV-2N protein and MxA, and analysed by flow cytometry. Live cells were assessed for SARS-CoV-2 N protein expression (D) and MxA induction, shown as mean fluorescence intensity (MFI; E). (F) Cells in the SARS-CoV-2-infected samples were further subdivided into SARS-CoV-2 N positive (N+) and SARS-CoV-2 N negative (N−) cells, and MxA MFI was determined within these subpopulations. Data in (A,C) are representative of two independent biological repeats. Data in (B,D–F) are pooled from two independent biological repeats, with bars representing the average.