Fig. 1: Experimental design and analysis of body weight changes, viral load and tissue pathology in SARS-CoV-2 and IAV infection.

a A schematic of the experiment and sample collection. Samples from each group were collected at 5, 15 and 30 dpi for serological analysis, histopathology and virus titration. Notably, tissue samples at 30 dpi were prepared for scRNA-seq analysis. Created with BioRender.com. b Body weight change data of the control group (CTRL, n = 20). c Survival rate of all three groups. d Body weight change data of the SARS-CoV-2 infection group (n = 80). e Proportions of the SARS-CoV-2 infection group based on body weight changes and mortality at 30 dpi. f Body weight change data of the IAV infection group (n = 80). g Proportions of the IAV infection group based on body weight changes and mortality at 30 dpi. h, i TCID₅₀ (h) and viral RNA copy number (i) of various tissues in the SARS-CoV-2 infection group at 5 dpi (n = 3). j, k TCID₅₀ (j) and viral RNA copy number (k) of various tissues in the IAV infection group at 5 dpi (n = 3). l, m Viral RNA copy number in nasal turbinates and lung tissues at 2-day intervals post-infection for SARS-CoV-2 (l) and IAV (m) (n = 3). n H&E, MT staining and RNAscope images. Enlarged images (scale bars, 2 mm) show whole lung images of H&E, with high-magnification images of corresponding areas stained with H&E, MT and RNAscope (scale bars, 500 μm). Light blue in MT-stained images indicates fibrosis, and red dots in RNAscope images represent detected viral RNA. o Graph showing the percentage of fibrosis area relative to total lung area based on MT staining results for each group (n = 4). Data for all graphs are presented as means ± s.d. Statistical significance is indicated as follows: *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, ns (P > 0.05), one-way ANOVA. SARS2, SARS-CoV-2.