Extended Data Fig. 1: Physical conditions of the infection mice at 5 dpi.

a, Representative images of WA1-, Delta-, and Omicron-infected mice 5 dpi. WA1-infected mice were lethargic and had a hunched posture, ungroomed coat, and squinted eyes. Delta-infected mice are mildly lethargic. Omicron-infected mice appeared normal. b, Representative images of lungs from mice infected with WA1, Delta, or Omicron at 2 dpi (n = 5), 4 dpi (n = 5), and 7 dpi (WA1 infection group n = 2, Delta n = 2 and Omicron n = 5). SARS-CoV-2 nucleocapsid is stained in green and nucleus is stained in blue. Scale bar, 2 mm. c, Representative images of tissue sections from lung tissue infected with WA1, Delta, or Omicron collected at 7 dpi (WA1 infection group n = 2, Delta n = 2 and Omicron n = 5). SARS-CoV-2 nucleocapsid is stained in green and nucleus is stained in blue. Scale bar, 300 μm. d, Representative images of mock infected lungs. SARS-CoV-2 nucleocapsid is stained in green and nucleus is stained in blue. Scale bar, 2 mm (left panel) and 300 μm (right panel), n = 5 mice.