Fig. 4: Characterization of Ob/Ob mice infected with MA-SARS-CoV-2.

a Virus titers in organs of MA-SARS-CoV-2-infected mice. Four mice per group were euthanized and virus titers in the lungs, nasal turbinate, brain, heart, liver, spleen, kidney, and intestine were determined by using plaque assays in VeroE6/TMPRSS2 cells. Dashed lines in the panels indicate the detection limit of the assay for each organ. n = 4 biologically independent animals. b Micro-CT imaging of the lungs of infected mice. Axial CT images of the thorax in MA-SARS-CoV-2-infected C57BL/6J mice and Ob/Ob mice. On day 4 post-infection, the MA-SARS-CoV-2-infected Ob/Ob mice had a higher degree of lung abnormalities than the infected C57BL/J mice, highlighted by the red circle. c Pathological features of MA-SARS-CoV-2-infected Ob/Ob mice. Representative images of lungs are shown. Left and middle columns show hematoxylin and eosin staining. Arrowheads indicate areas of inflammatory cell infiltration. Right column shows immunohistochemistry using a rabbit polyclonal antibody that detects SARS-CoV-2 nucleocapsid protein, with brown staining indicating virus-positive cells. Scale bars, 500 µm in the left column; 100 µm in the middle and right columns. d Histopathological scores for inflammation in the alveoli. Ns not significant. n = 3 biologically independent animals. e Population of immune cells in the lungs of MA-SARS-CoV-2-infected mice. Lung immune cell numbers were determined in the whole lung at 4 dpi in C57BL/6J mice and Ob/Ob mice by flow cytometry. n = 5 biologically independent animals. a, d, e Each dot represents data from an individual animal and the horizontal bars represent means ± SD. Source data are provided as a Source Data file.