Fig 1: Photomicrographs of immunohistochemically (IHC) stained lung sections from uninfected and SARS-CoV-2–inoculated hamsters. A–D: IHC staining using antibodies against endothelial cells [ECs; von Willebrand factor/factor 8 (F8); A], macrophages [macs; ionized calcium-binding adaptor molecule 1 (Iba1); B], T lymphocytes (T-cells; CD3; C), and B lymphocytes (B-cells; CD79a; D), where positive cells exhibit intracytoplasmic or membranous brown staining. A–D: Insets: Higher-magnification views of the black boxed areas. Overall, IHC indicates that the subendothelial mononuclear cell infiltrate is composed primarily of macrophages. See Supplemental Figure S2 for internal controls. Scale bars = 20 μm (A–D). Dpi, days post inoculation.