Fig. 4: The furin CS of SARS-CoV-2 allows for efficient replication and transmission in a ferret model.
From: The furin cleavage site in the SARS-CoV-2 spike protein is required for transmission in ferrets
a,b, Head-to-head transmission experiment of WT and ΔCS SARS-CoV-2 in ferrets. In each group, four individually housed donor ferrets were infected with 105 p.f.u. of either WT or ΔCS SARS-CoV-2. At 1 d post-inoculation, naïve contact ferrets were added to each donor ferret. Ferrets were sampled by nasal wash daily and donor (a) and direct contact (b) ferret virus titres were determined by E gene quantitative PCR. Statistics were determined by multiple two-tailed t-tests of the log-transformed E gene copy numbers between each group. *P ≤ 0.05. c,d, Competition transmission experiment of SARS-CoV-2 mix of WT and ΔCS in ferrets. Four individually housed donor ferrets (c) were infected with 105 p.f.u. of virus mix containing ~70% ΔCS and ~30% WT. At 1 d post-inoculation, naïve contact ferrets (d) were added to each donor ferret. Ferrets were sampled by nasal wash daily and virus titres were determined by E gene quantitative PCR. For donors on days 2, 3, 5, 6 and 8, and for contacts on days 3, 6, 8 and 9, viral RNA across the S1/S2 CS was deep sequenced. Where sequencing data were obtained, bars showing the ratios of WT and deletion are shown. Inoc., inoculum. Dotted lines indicate limits of detection.
