Gtx635654

A 10% buffered formalin solution was prepared to fix all the collected tissues and organs. Paraffin sections (3–4 mm in thickness) were cut following established procedures. All the lung sections were stained with hematoxylin and eosin. The histopathological observation was carefully recorded by observing slides using an Olympus microscope. For IHC staining, to identify the expression of SARS-CoV-2 S protein (GTX635654, 1:200; GeneTex, Irvine, CA), dehydrated paraffin sections (3–4 µm in thickness) were treated with an antigen retrieval kit (AR0022; Boster Bio, Pleasanton, CA) and quenched for endogenous peroxidases in three percent H₂O₂ in methanol for 10 min. After blocking in 1% normal goat serum for 1 h at 37 °C, the sections were stained with anti-SARS-CoV-2 rabbit monoclonal antibody at 4 °C overnight, followed by incubation with a horseradish peroxidase HRP-labeled goat anti-rabbit IgG secondary antibody (ZDR-5306, 1:200; ZSGB Bio) for 1 h at 37 °C. Finally, the sections were visualized by incubation with 3,3′-diaminobenzidine tetrahydrochloride (DAB) and viewed carefully by an Olympus microscope.