FIG. 8.

Light photomicrographs of alveolar parenchyma from 12-month-old mice that were mock inoculated (A) or inoculated with recombinant SARS-CoV spike glycoprotein variant icUrbani (B), icGZ02 (C), icHC/SZ/61/03 (D), icCUHK-W1 (E), or icA031G (F) and sacrificed 4 days after inoculation. No microscopic lesions are evident in panel A, B, E, or F. Diffuse acute alveolitis with alveolar septal congestion (dotted arrows with open arrowhead) and numerous hyaline membranes in alveolar airspaces (arrows with closed arrowheads) are present in panels C and D. AL, alveoli; AD, alveolar ducts; BV, blood vessels. Tissues were stained with hematoxylin and eosin. Scaling bars, 50 μm.