Fig. 1: MISTRG6 humanized mice that transiently express hACE2 can be infected with SARS-CoV-2.

a, Schematic of experimental design. MISTRG6 mice were neonatally reconstituted with human CD34⁺ cells. After confirmation of human immune cell humanization in circulation, reconstituted MISTRG6 mice were injected with AAV-hACE2 (10¹¹ genomic copies per milliliter) intratracheally (MISTRG6-hACE2). After a 2-week acclimation and recovery period, MISTRG6-hACE2 mice were infected intranasally with SARS-CoV-2 (10⁶ PFU). b, Viral RNA (quantification of N gene) in homogenized lung tissue at 2, 4, 7, 14 and 28 dpi in B6 control or reconstituted or unengrafted MISTRG6 mice expressing or lacking human ACE2. Group 1: n = 4 (2 dpi), 3 (4 dpi), 3 (7 dpi), 3 (14 dpi) and 3 (28 dpi) biologically independent mice examined over two independent experiments. Group 2: n = 4 (2–28 dpi) biologically independent mice examined over two independent experiments. Group 3: n = 4 (2 dpi), 4 (4 dpi), 7 (7 dpi), 4 (14 dpi) and 2 (28 dpi) biologically independent mice examined over three independent experiments. Group 4: n = 4 (2 dpi), 26 (4 dpi), 6 (7 dpi), 8 (14 dpi) and 8 (28 dpi) biologically independent mice examined over at least four independent experiments. Group 5: n = 3 (2 dpi), 11 (4 dpi), 3 (7 dpi), 3 (14 dpi) and 2 (28 dpi) biologically independent mice examined over at least two independent experiments. Significance in viral RNA was determined by Mann–Whitney, two-tailed test. Individual values for each mouse and means are presented. c, Viral titers measured by PFU (using standard Vero E6 cells) in homogenized lung tissue at 2, 4, 7, 14 and 28 dpi in B6 control or reconstituted or unengrafted MISTRG6 mice expressing or lacking human ACE2. Group 1: n = 4 (2 dpi), 4 (4 dpi), 2 (7 dpi) biologically independent mice examined over two independent experiments. Group 2: n = 4 (2 dpi), 4 (4 dpi), 2 (7 dpi) biologically independent mice examined over two independent experiments. Group 3: n = 4 (2 dpi), 6 (4 dpi), 2 (7 dpi), 3 (14 dpi) biologically independent mice examined over three independent experiments. Group 4: n = 4 (2 dpi), 11 (4 dpi), 6 (7 dpi), 4 (14 dpi) and 4 (28 dpi) biologically independent mice examined over at least four independent experiments. Group 5: n = 3 (2 dpi), 7 (4 dpi), 4 (7 dpi), 3 (14 dpi) and 2 (28 dpi) biologically independent mice examined over at least two independent experiments. One-sample t and Wilcoxon tests were used for comparison of viral titers. Individual values for each mouse and means are presented. d, Weight change during the course of infection plotted as percent change compared to original weight measured just before inoculation with SARS-CoV-2. Group A–D n = 7 and Group E n = 8 biologically independent mice examined over at least three independent experiments for 28 d. Means with s.d. are presented. Ordinary one-way ANOVA compared to the mean of uninfected reconstituted MISTRG6 mice (Group A) with Dunnett’s multiple comparison test was used. Group E P < 0.0001; Group D P = 0.2889; Group C P = 0.8926; Group B P = 0.9974. Means with s.d. are plotted. Individual values for Group E are presented in Supplementary Fig. 1c. e, Representative images of H&E staining (×2 and ×10 magnification) and box and whisker plot (minimum to maximum) of the histopathological scores and percent area affected of infected (2, 4, 7, 14, 28 and 35 dpi) or uninfected lungs. The whiskers go down to the smallest value (minimum) and up to the largest value (maximum). The box extends from the 25th to 75th percentiles. The median is shown as a line in the center of the box. Uninfected, n = 9; 2 dpi, n = 5; 4 dpi, n = 14; 7 dpi, n = 6; 14 dpi, n = 11; 28 dpi, n = 10; and 35 dpi, n = 6 biologically independent mice examined over at least three independent experiments. Ordinary one-way ANOVA compared to uninfected lungs was used. P value was adjusted by Sidak’s multiple comparisons test. f, Trichrome staining of infected (2, 4, 7, 14, 28 and 35 dpi) or uninfected lungs. Representative images (×40) and box and whisker plot (minimum to maximum) of the histopathological scores are presented. Arrows indicate areas with collagen deposition. The extent of fibrosis was determined by the thickness of collagen bundles. The whiskers go down to the smallest value (minimim) and up to the largest value (maximum). The box extends from the 25th to 75th percentiles. The median is shown as a line in the center of the box. Uninfected, n = 7; 2 dpi, n = 3; 4 dpi, n = 4; 14 dpi, n = 12; 28 dpi, n = 8; 35 dpi, n = 4 biologically independent mice examined over at least three independent experiments. Ordinary one-way ANOVA compared to uninfected lungs was used. P value was adjusted by Sidak’s multiple comparisons test. Representative images of all time points are presented as part of Supplementary Fig. 1f. NS, not significant.