Fig. 3: Comparison of lesions in the lungs of CJ-1 and IT-1.

Anterior–posterior and right lateral chest radiographs (a) were collected from rhesus macaques prior to SARS-CoV-2 inoculation (day 0) and at 3, 5, and 7 dpi. Areas of interstitial infiltration, indicative of pneumonia, are highlighted (red circle); obscure costophrenic angles (red arrows) and patchy lesions (blue circle) are also shown. The histopathological and immunohistochemical observations in the lungs are shown (b). Both macaques exhibited interstitial pneumonia with a thickened alveolar septum; the infiltration of inflammatory cells, mainly lymphocytes and macrophages; and some amount of exudation (red arrows) in the alveolar cavities at 7 dpi. Infection via the conjunctival route caused relatively mild pneumonia. Sequential sections were stained by H&E and subjected to IHC. Viral antigens were observed primarily in the alveolar epithelia (black arrows), along with detached degenerative cellular debris (green arrows). H&E-stained sections are shown at ×100 magnification and magnified at ×400 magnification (black frame). The IHC image shows the same field outlined in black at ×400 magnification. Black scale bar = 100 µm, red scale bar = 50 µm. Data (b) are representative of three independent experiments.