Fig. 3

S-M1237I mutation in the SARS-CoV-2 Alpha strains associates with higher viral protein levels but lower plaque forming capability. (A)(B) Representative immunoblot results of viral protein expression in Calu-3 cells (A) and in supernatants (B) after 24 h post infection with SARS-CoV-2 isolates (S-M1237-Alpha and S-I1237-Alpha (T-III) variants, MOI = 0.1). The relative ratio of S, N, and M protein in the supernatant was normalized with NTU52 (set as 1). The relative ratios were listed below the immunoblot in left panel and graphically illustrated in right panel of (B). (C) Comparison of viral titers (plaque-forming units (PFU)/mL) in the supernatants of Calu-3 cells infected with SARS-CoV-2 isolates (S-M1237-Alpha and S-I1237-Alpha (T-III) variants, MOI = 0.1) at 24 h post-infection. Data are presented as the mean ± SD (P < 0.01^**; P < 0.001^***)