Fig. 6: Virulence of SARS-CoV-2 recombinant viruses in experimentally infected hamsters.
From: Phenotypic evolution of SARS-CoV-2 spike during the COVID-19 pandemic
Syrian hamsters were intranasally inoculated with the indicated recombinant viruses (3.75 × 106 genome copies per animal) or mock infected and killed at 6 dpi. a, Daily body weight changes of infected and uninfected hamsters. Data are median ± 95% confidence interval. Each group is n ≥ 6 animals. Weight comparisons were performed using two-way ANOVA and the Holm–ŠĂdák post hoc test. The calculated P values are indicated in the figures. b, Representative photomicrographs of one lung lobe section stained using immunohistochemistry with antibodies for IBA1, CD3 and TTF-1. Scale bar, 2 mm. c–e, Quantification of each marker for experiments shown in b using whole-section software-assisted imaging. Data are median ± 95% CI and expressed as relative quantification of markers detected in hamsters infected with S:B.1 (set as 1.0 for each marker). f, Viral load in nasopharyngeal swabs at 24 hpi in each infected animal. The copy numbers of viral RNA in the resuspended swabs collected from infected hamsters were quantified by RT–qPCR. Data are mean ± s.e.m. of n ≥ 6 animals. In c–e, statistical significance of differences between S:B.1 and other spike SARS-CoV-2 was determined using one-sample t-test, while statistical significance of differences between S:BA.1 and other post-Omicron recombinant viruses was determined using one-way ANOVA with multiple comparisons between conditions using the Holm–ŠĂdák post hoc test. *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001, ****P ≤ 0.0001, and exact P values are indicated in figures.
