Representative histopathological changes of the intestine and spleen. A, H&E and immunofluorescence staining of intestinal tissue at 2 dpi. (a) Mock-infected hamster's intestine; (b) and (c) intestinal mucosal epithelia and Peyer’s patches of virus-challenged hamsters at 2 dpi; (d) a few mucosal epithelial cells and interstitial histiocytes were found weakly positive for viral NP (arrows); (e) epithelial cell necrosis and (f) viral NP expression (arrows) in the intestine at 4 dpi. B, Images of H&E- and TUNEL-stained spleen sections at 2 dpi and 4 dpi showing depletion of white and red pulps with reduced number and size of follicles and increased apoptosis. Abbreviations: dpi, days postinoculation; H&E, hematoxylin and eosin; NP, nucleocapsid protein; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; TUNEL, terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling.