Fig. 2

Expression of SARS-CoV-2 receptor and cofactor proteins in respiratory epithelium as analyzed by immunohistochemistry. Representative screenshots of immunohistochemistry (IHC) images from The Human Protein Atlas (www.proteinatlas.org). a-b ACE-2 IHC images from the nasopharynx (n = 4), bronchi (n = 3), lungs (n = 6), and oral mucosa (n = 4). Positive control: duodenum tissue (n = 6). c TMPRSS2 IHC images from the nasopharynx (n = 3), bronchi (n = 2), lungs (n = 3), and oral mucosa (n = 3). Positive control: prostate tissue (n = 3). d-e BSG/CD147 IHC images from the nasopharynx (n = 2), bronchi (n = 3), lungs (n = 6), and oral mucosa (n = 5). Positive control: heart tissue (n = 3). f Furin IHC images from the nasopharynx (n = 3), bronchi (n = 3), lungs (n = 3), and oral mucosa (n = 3). Positive control: salivary gland tissue (n = 3). Red arrows indicate IHC positive cells morphologically consistent with alveolar macrophages. Scale bars, lower left of respective images. Images were analyzed by a board-certified surgical pathologist (C.M.S.)