Ileal & myocardial expression of SARS-CoV and influenza virus activating proteases and receptors.

<p>Ileum (A–D) and myocardium (E–H) immunostained for TMPRSS2 (A&E), ACE2 (B&F) and HAT (C&G), or stained for 2,6-linked sialic acid (D&H; detected with elderberry (<i>Sambucus nigra</i>) lectin). All positive reactions are detected with the peroxidase technique (brown) and the tissue is counterstained with haematoxylin (blue). (A) There is strong positive anti-TMPRSS2 immunostaining of ileal epithelium (Ep) and also of lymphocytes (Ly) within the core of the villus. (B) There is strong positive anti-ACE2 immunostaining of ileal epithelium (Ep) and also of lymphocytes (Ly) within the core of the villus. (C) There is strongly positive anti-HAT immunostaining of the basal part of the ileal epithelial cells (Ep), but only weak positive immunostaining of occasional lymphocytes (Ly) within the villus core. (D) All structures are strongly stained for 2,6-sialic acid, including ileal epithelium (Ep) and lymphocytes (Ly). (E) There is strong positive anti-TMPRSS2 immunostaining of cardiac myocytes. (F) There is strong positive anti-ACE2 immunostaining of some cardiac myocytes. (G) There is no anti-HAT immunostaining of cardiac myocytes. (H) There is strong 2,6-sialic acid staining of cardiac myocytes. Scale bar = 50 microns (shown in panels D and H and also pertaining to 3 preceding panels in each case).