Fig. 1: Distinct replication, S cleavage and competition for ΔPRRA SARS-CoV-2.
From: Loss of furin cleavage site attenuates SARS-CoV-2 pathogenesis
a, Schematic of SARS-CoV-2, showing deletion of the furin cleavage site. ORF3, ORF6, ORF7 and ORF8 are designated 3, 6, 7 and 8, respectively. b, SARS-CoV-2 trimer (grey) with ΔPRRA mutant monomer overlaid (red). The loop (inset) shows wild-type SARS-CoV-2 (WT) (cyan) with the PRRA sequence (blue) and ΔPRRA mutant (pink). Models were generated using the structure of SARS-CoV (Protein Data Bank code 6ACD). c, Viral titre from Vero E6 cells infected with wild-type (black) or ΔPRRA (blue) SARS-CoV-2 at an MOI of 0.01 (n = 3). d, Purified SARS-CoV, wild-type SARS-CoV-2 and ΔPRRA SARS-CoV-2 virions from Vero E6 cells probed with anti-S (top) or anti-N antibody (bottom). Full length (FL), S1/S2 cleavage form and S2′ are annotated. Results are representative of two independent experiments. e, Competition assay between wild-type (black) and ΔPRRA (blue) SARS-CoV-2, showing RNA percentage based on RT–qPCR at 50:50 (top), 90:10 (middle) and 10:90 (bottom) ratios of wild type:ΔPRRA (n = 3 per group). f, Viral titre from Calu-3 2B4 cells infected with wild-type (black) or ΔPRRA (blue) SARS-CoV-2 at an MOI of 0.01 (n = 3). g, Purified SARS-CoV, wild-type SARS-CoV-2 and ΔPRRA SARS-CoV-2 virions from Calu-3 2B4 cells probed with anti-S (top) or anti-N (bottom) antibody. Results are representative of two independent experiments. h, Viral titre from Vero E6 cells expressing TMPRSS2, infected with wild-type (black) or ΔPRRA (blue) SARS-CoV-2 at an MOI of 0.01 (n = 5). i, Competition assay between wild-type (black) and ΔPRRA (blue) SARS-CoV-2 in Vero E6 cells expressing TMPRSS2, showing RNA percentage based on RT–qPCR at 50:50 ratio of wild type:ΔPRRA (n = 3 per group). j, Purified SARS-CoV, wild-type SARS-CoV-2 and ΔPRRA SARS-CoV-2 virions from Vero E6 cells expressing TMPRSS2, probed with anti-S (top) or anti-N (bottom) antibody. Results are representative of two independent experiments. Data are mean ± s.d. in c, e, f, h, i. P values from two-tailed Student’s t-test.
