Fig. 6. The furin-like cleavage site in SARS-CoV-2 spike is required for efficient SARS-CoV-2 replication in human lungs.

a Seven cell types of human and non-human origin, including Caco2 (human intestine), Calu3 (human lung), Huh7 (human liver), CRFK (cat), RK13 (rabbit), PK15 (pig), and VeroE6 (monkey) were infected with SARS-CoV-2 or SARS-CoV-2 S₁/S₂mut at 0.2 MOI. Cell lysates were collected at 24hpi for viral genome copy analysis by qRT-PCR (n = 3). b The expression of TMPRSS2, cathepsin L, cathepsin B, and furin from Caco2, Calu3, Huh7, and VeroE6 were analyzed with qRT-PCR (n = 3). c Schematic of ex vivo human lung and intestinal tissue infection. d–g Human lung and intestine tissues were infected with SARS-CoV-2 or SARS-CoV-2 S₁/S₂mut. Cell lysate and supernatant samples were harvested at the indicated time points for qRT-PCR analysis (n = 3). h The expression of ACE2, TMPRSS2, cathepsin L, cathepsin B, and furin from human lung and intestinal tissues were determined with qRT-PCR (n = 8 for TMPRSS2 in intestine and n = 9 for other groups). Data represented mean and standard deviations from the indicated number of biological repeats. Statistical significance between groups was determined with two way-ANOVA (d and f), one way-ANOVA (b), or two-sided unpaired Student’s t test (a, e, g, and h). * represented p < 0.05, ** represented p < 0.01, *** represented p < 0.001, **** represented p < 0.0001. ns not significant. Source data are provided as a Source Data file.