Figure 7.

ACE2 cell surface expression is not affected by silencing of endogenous IFITM expression and critical for SARS-CoV-2 infection

(A) Calu-3 cells were transfected twice with non-targeting control (NT) or with IFITM1, 2 or 3 siRNAs (with or without IFN-β treatment). Six hours after the second transfection, cells were stained with anti-ACE2 antibody and images acquired using the LSM system. ACE2 signal intensities at the cell surface and in the cytoplasm were quantified using ImageJ.

(B) Calu-3 cells were transfected twice with NT or IFITM1, 2 or 3 siRNAs as described in panel A, permeabilized or not, stained with anti-ACE2 antibody and analyzed by flow cytometry. Bar diagrams in panel B and C represent the mean of three independent experiments (±SEM).

(C) Calu-3 cells were treated with NT or ACE2 siRNAs, infected with the SARS-CoV-2 Hu-1 or Delta variants (MOI 0.05) and viral RNA production in the cell culture supernatants determined by qRT-PCR two days later.

(D) Schematic heatmap summarizing the effects of IFITMs on S-containing viral pseudo-particles and genuine hCoVs. Note that this overview is provisional and results may vary depending on the experimental conditions and cell types used.