Fig. 5: K18 hACE2 transgenic mice develop rhinitis, pneumonia with associated pulmonary inflammation after infection with SARS-CoV-2.

a–d and i–l WT C57BL/6 mice. Minimal mononuclear and neutrophilic interstitial pneumonia in WT lung at 2 DPI a, b bracket. By 4 DPI c, d minimal alveolar histiocytosis d, asterisk pneumocyte type II cells d, arrowheads, perivascular mononuclear inflammation d, bracket and rhinitis with low numbers of neutrophils k, arrowhead were variably observed. Lymphocyte aggregates in the lamina propria of the small intestine i, asterisk. Mixed mononuclear inflammation with individual hepatocellular necrosis j, arrowhead. Brain from WT 4 DPI was normal l. e–h and m–p K18 hACE2 transgenic mice. Interstitial pneumonia e, f associated with alveolar histiocytosis admixed neutrophils and lymphocytes f, asterisks, mild type II pneumocyte hyperplasia f, arrowhead, bronchiolar syncytia (f, arrow), endothelial cells hyperplasia and vasculitis (f, bracket) by 2 DPI. Gut-associated lymphoid tissue (GALT) with prominent germinal centers was observed (m, asterisk). Liver inflammation with variable amounts of individual hepatocellular necrosis (n, arrowhead). Greater lung involvement indicative of pneumonia (g), with inflammatory cellular accumulations and hemorrhage in alveolar spaces (h, asterisk) and interstitium (h, bracket), intra-alveolar fibrin admixed cellular debris (h, arrow), vasculitis (h, bracket), edema (h, arrowhead) by 4 DPI. Neutrophilic rhinitis observed at 4 DPI (o, bracket). Mild meningoencephalitis with vasculitis (p, arrowhead). Representative images of n = 8 (50:50 male:female per time-point and group) randomly chosen. Scale bars left images, 1 mm. Scale bars right images, 50 μm. DPI days post infection. Data are representative over two independent experiments.