Fig. 2: The furin CS of SARS-CoV-2 spike allows more efficient serine-protease-dependent entry into airway cells.
From: The furin cleavage site in the SARS-CoV-2 spike protein is required for transmission in ferrets
a–c, Inhibition of entry of lentiviral PVs into 293T-ACE2 (a), Caco-2 (b) or Calu-3 (c) cells by the serine protease inhibitor, camostat (green bars), or the cathepsin inhibitor, E64-d (purple bars). Assays were performed in triplicate and are plotted as mean + s.d. Data shown are a representative replicate (n = 3). All data were normalized to no drug control (black bars). Statistics were determined by two-way ANOVA with multiple comparisons against the no drug control. *0.05 ≥ P > 0.01; **0.01 ≥ P > 0.001; ***0.001 ≥ P > 0.0001; ****P ≤ 0.0001. d, Replication kinetics of SARS-CoV-2 WT and ΔCS viruses in HAE cells. Cells were pretreated with control media or media containing camostat for 1 h then infected at an MOI of 0.1. Assays were performed in triplicate and are plotted as mean + s.d. Statistics were determined by one-way ANOVA with multiple comparisons on log-transformed data. Black P values indicate statistical significance between no drug controls of WT and ΔCS, while coloured P values indicate significance between no drug control or camostat. Dotted line indicates limit of detection. e–h, Gene expression of selected SARS-CoV-2 entry factors in 293T-ACE2 (e), Caco-2 (f), Calu-3 (g) or HAEs (h). Gene expression was determined by RT–qPCR and normalized to β-actin. Assays were performed in triplicate and are plotted as mean + s.d. Data shown are a representative replicate (n = 2), except for primary HAEs, where data points represent repeats in (n = 3) independent donors. Camo, camostat; ND, not detectable.
