Fig. 1.

Infectivity of SARS-CoV-2 in A549 cells under submerged culture condition

(A) Growth curves of SARS-CoV-2 in A549 and Calu-3 cells. Viral titers in the culture supernatant were determined using a plaque assay. (B and C) SARS-CoV-2 RNA levels in Calu-3 cells (B) and A549 cells (C) were quantified by qRT-PCR and were normalized to the expression levels of β-actin. (D and E) Expression levels of exogenously transduced ACE2 (D) and TMPRSS2 (E) were quantified by qRT-PCR and normalized to the expression levels of β-actin. (F) Expression of exogenously transduced proteins was detected by Western Blotting with antibodies specific to the proteins indicated on the left. The full-length and cleaved forms of TMPRSS2 are indicated by close and open arrowheads, respectively. Asterisks indicate nonspecific bands that cross-reacted with anti-TMPRSS2 antibody. (G) Growth curves of SARS-CoV-2 in A549 cells expressing ACE2 and TMPRSS2. Viral titers in the culture supernatant were determined using a plaque assay. (H) The levels of SARS-CoV-2 N gene at 72 hpi were quantified by qRT-PCR and normalized to the expression levels of β-actin. The values in the graphs are expressed as the mean ± SD of triplicate samples.