Fig. 5

Comparative pulmonary histologic lesions in AGMs infected with SARS-CoV-2. Representative tissues of AGM from 5 dpi (a-e & o) and 34 dpi (f-j). SARS-CoV-2 naïve tissues from an AGM (k-n). H&E staining at low magnification (20x) (a, f, & k) and higher magnification (40x) (b, g, l, and f inset) of pulmonary alveolar septae and alveolar spaces. Moderate neutrophilic bronchiolitis and alveolitis and mild interstitial pneumonia with congestion (a & b) Moderate lymphohistocytic interstitial pneumonia with congestion, mild alveolar wall fibrosis (f & g) and moderate perivascular lymphocytic cuffs (f inset). No significant lesions (k & l). IHC for anti-fibrin antigen (red) (c, h & m). Alveolar spaces are partially to completely flooded with fibrin (c) Minimal intravascular fibrin labeling (h) and no significant fibrin immunolabeling (m). Trichrome special stain for collagen (blue) (d, i & n). Minimal to mild alveolar wall collagen deposition (d) moderate alveolar wall collagen deposition (i) and minimal collagen staining of alveolar wall basement membranes (n). IHC labeling for anti-SARS-CoV2 antigen (red) (e, j & o). IHC positive type I pneumoncytes (black arrows) and type II pneumoncytes (white arrow) localized with alveolar inflammation (e), No immonolabeling (j) and IHC positive labeling of respiratory epithelium of the bronchus (o). Images captured at 20x (m, d, i, n, & j) and 40x (c, h, e, & o)