Figure 6.
Histopathological and immunohistochemistry findings in SARS-CoV-2-infected mice. The lungs and spleens were collected from the control mice infected with SARS-CoV-2 without equine immunoglobulin drug injection at 3dpi, and the lungs, spleens, livers and kidneys were harvested from recovered mice. After each tissue was embedded in paraffin, the sections were sectioned for HE staining. (A, B, E, F) Lung tissue changes of control mice were characterized by more necrotic epithelial cells (blue arrow), a small amount of neutrophil infiltration, and perivascular edema with a small amount of inflammatory cell infiltration in the local alveolar cavity (yellow arrow). (C, D, G, H) Spleen tissue changes of control mice were characterized with spotted apoptosis of lymphocytes, nuclear pyknosis and deep staining or fragmentation in the spleen nodules (black arrows), and the expansion of germinal centers (yellow arrow), scattered neutrophils mostly seen in the red pulp granulocyte infiltration (red arrow), and more brown‒yellow particles in the red pulp (blue arrow). (I-L) The basically normal structure of the lung, spleen liver, and kidney tissues were found in administration groups given equine IgG or F(ab’)2. The figure showed immunohistochemistry (IHC) labeling against SARS-CoV-2 N. (M) Viral antigen was not detectable in prevention group given purified IgG; (N) Viral antigen was not detectable in prevention group given purified F(ab’)2; (O) Viral antigen was detected for positive in prevention control group; (P) Viral antigen was not detectable in treatment group given purified IgG; (Q) Viral antigen was not detectable in treatment group given purified IgG F(ab’)2; (R) Viral antigen was detected for positive in treatment control group. (scale bar = 100 μm).