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. 2023 Mar 13;26(4):106395. doi: 10.1016/j.isci.2023.106395

Figure 4.

Figure 4

Endogenous IFITM expression is critical for efficient SARS-CoV replication

(A) Quantification of viral E gene RNA by qRT-PCR in the supernatant of Calu-3 48 h post-infection with SARS-CoV-1, SARS-CoV-2 or 24 h post-infection with MERS-CoV. Cells were transiently transfected with siRNA either control (CTRL) or targeting IFITM2 as indicated. In addition, cells were either treated with IFN-β (250 U/ml for SARS-CoV and 50 U/ml for MERS-CoV) or left untreated. Bars in all panels represent the mean of three independent experiments (±SEM). ∗, p < 0.05; ∗∗; p < 0.01; ∗∗∗, p < 0.001. The numbers directly above the bars indicate fold change compared to cells treated with control (CTRL) siRNA and number below the horizontal lines fold reduction on IFN-β treatment.

(B and C) Infectious SARS-CoV-1, SARS-CoV-2 or MERS-CoV particles in the supernatant of (A) as assessed by plaque-forming units assay. Panel C shows primary data.

(D) Viral E gene RNA levels in the supernatant of Calu-3 48 h post-infection with SARS-CoV-1 or 24 h post-infection with MERS-CoV. Cells were transiently transfected with control siRNA (CTRL) or siRNA targeting IFITM2 or IFITM3 as indicated. Cells were either treated with IFN-β (100 U/ml for SARS-CoV-1 or 50 U/ml for MERS-CoV) or left untreated.

(E) Infectious SARS-CoV-1 or MERS-CoV particles in the supernatant of (D) as assessed by plaque-forming units assay. Bars in all panels represent the mean of three independent experiments (±SEM); ∗, p < 0.05; ∗∗, p < 0.01; ∗∗∗, p < 0.001. See also Figure S2.