FIG 10.

Lung pathology score after challenge with SARS-CoV-2. Fixed lung tissues from day 4 after SARS-CoV-2 challenge were embedded in paraffin, sectioned at 5 μm, deparaffinized, rehydrated, and stained with hematoxylin and eosin (H&E) for the examination of histological changes under light microscopy. Each slide was quantified based on the severity of histologic changes, which included interstitial pneumonia, alveolar damage, multinucleated giant cells, extensive inflammation, bronchiolitis, pulmonary hemorrhage, mononuclear cell infiltration, and peribronchiolar inflammation. 4 = extremely severe lung pathological changes; 3 = severe lung pathological changes; 2 = moderate lung pathological changes; 1 = mild lung pathological changes; 0 = no pathological changes.