FIG 8.

Inhibition of SARS-CoV-2 replication by type I IFN in A549-ACE2 and Caco-2-ACE2 cells. Human A549-ACE2 (A, C, and E) and Caco-2-ACE2 (B, D, and F) cells, as indicated, were pretreated or not with IFN for 16 to 20 h, then the medium was replaced and cells were mock infected (N.I.) or incubated with SARS-CoV-2 at the indicated MOIs. (A and B) Cells were harvested and lysed for RNA extraction and RT-qPCR analysis using RdRp primers and probe. (C and D) Cells were fixed with PFA, permeabilized, and stained with an anti-spike antibody conjugated to an Alexa fluorochrome. The percentage of spike(+) cells was scored by flow cytometry. (E and F) Cells were lysed for immunoblot analysis of SARS-CoV-2 nucleoprotein (N) and spike, IFITM3, RIG-I, and MX1 ISG expression levels. Actin serves as a loading control. Representative immunoblots are shown. Of note, MX1 was not detected in Caco-2-ACE2 cell lysates. The means of three independent experiments are shown (A to D), with error bars representing one standard deviation (SD) from the mean.