Fig. 5
Contact transmission of B.1.351 in wild-type mice. a Schematic of experimental design and sample collection of close-contact transmission assay. Twelve C57BL/6 mice were inoculated with 5 × 106 FFU of B.1.351 virus on Day 0 and assigned to two cages (n = 6 for each cage). On Day 1 post inoculation, six naive mice were assigned into each cage. On Day 7, three inoculated mice and three contact mice from both cages were euthanized to detect viral RNA copies. On Day 14, three inoculated mice and three contact mice from both cages were euthanized for serological detection. As a control, B.1.351-infected hACE2 mice were co-housed with naive hACE2 mice (6:6 ratio, 2 cages). Viral and serological detections were conducted as above. The body weight changes were monitored every 2 days. b, c The viral RNA copies of lung and trachea samples from B.1.351-infected and close-contact mice were quantified and represented as log10 copies per ml (n = 6). d, e Reactivity of the serum samples from B.1.351-infected and close-contact mice with SARS-CoV-2 S antigens. Both anti-S IgM and anti-S IgG of these sera were detected. The absorbance at 450 nm represented the relative amount of antibodies (n = 6). f The body weight changes of both B.1.351-inoculated and close-contact mice. The body weight of each mouse was monitored every 2 days. Data in b–f are represented as mean ± SEM in sextuplicate. p Values in b–e were calculated by one-way ANOVA with Tukey’s multiple comparison test, which compared the mean of each group with the mean of every other group. p Values in f were calculated by two-way ANOVA with Dunnett’s multiple comparisons test, which compared the mean of each group with the mean of the first group. ns = p ≥ 0.05, *p < 0.05, ***p < 0.001, ****p < 0.0001
