Figure 1.
Schedule of SARS-CoV-2 pre- and reinfection in ferrets. To induce varied immune responses, three different doses of SARS-CoV-2 were used to infect groups of ferrets. Following three weeks of infection, serum NAb titres were measured in Vero cells, and ferrets were then grouped according to their NAb titres (NAb < 20, 20–40, 80, and 160) (A). Asterisks indicate statistical significance between each infection group as determined by two-way ANOVA Tukey’s multiple comparisons test (* indicates p < 0.05, ** indicates p < 0.0001). Each group of NMC-nCoV02 (S clade)-primed ferrets and the naive control group were inoculated intranasally with 105.0 TCID50 of CBNU-nCoV02 (GH clade) followed by virus and blood collection on day 14 post-infection (B).