A Mouse Model for Betacoronavirus Subgroup 2c Using a Bat Coronavirus Strain HKU5 Variant

Agnihothram, Sudhakar; Yount, Boyd L.; Donaldson, Eric F.; Huynh, Jeremy; Menachery, Vineet D.; Gralinski, Lisa E.; Graham, Rachel L.; Becker, Michelle M.; Tomar, Sakshi; Scobey, Trevor D.; Osswald, Heather L.; Whitmore, Alan; Gopal, Robin; Ghosh, Arun K.; Mesecar, Andrew; Zambon, Maria; Heise, Mark; Denison, Mark R.; Baric, Ralph S.

Although little if any pathology was noted in young infected animals, aged mice developed more-severe airway disease, perivascular and peribronchial cuffing, and pneumonia by 4 days p.i. The airway disease ( Fig. 3C and D, bottom) included denuded regions of the airway epithelium, debris in the lumen of small airways, and peribronchial cuffing with increased numbers of neutrophils and monocytes. Perivascular cuffing was also evident, with large numbers of infiltrating neutrophils and monocytes. A few animals developed focal regions of severe pneumonia with accompanying edema-filled alveoli, consistent with early acute DAD (Fig. 3D , bottom). To identify cellular targets, immunohistochemistry with polyclonal serum to HKU5 N protein was performed in lung sections of young and aged mice. As seen with SARS-CoV (25), BtCoV HKU5-SE antigens were abundant in airway epithelial cells and in epithelial cells with features characteristic of type II pneumocytes in the alveoli (Fig. 4) . No staining was noted in mockinfected lungs (Fig. 4 , top and bottom, far right).