Angiotensin-Converting Enzyme 2 (ACE2) is a transmembrane protein found in the lungs, intestines, heart, kidney, liver and arteries that plays a central role in vascular, renal, and myocardial physiology. The normal function of ACE2 is to convert the inactive vasoconstrictor angiotensin I (AngI) to Ang1-9 and the active form AngII to Ang1-7. It is involved in controlling vascular function including blood pressure, and absence of ACE2 expression in ace2-/ace2- mice leads to severely reduced cardiac contractility, indicating its importance in regulating heart function. ACE2 is also the primary attachment receptor for HCoV-N63, SARS-CoV and SARS-CoV-2. The S1 portion of the coronavirus spike protein attaches to ACE2 presented on the host cell surface. The SARS-CoV-2 virus targets pneumocytes and macrophages expressing ACE2 in the lung, and it is believed to infect ACE2-positive cells in other tissues including the gastrointestinal tract and potentially the liver (in cholangiocytes). Hoffmann et al., 2020, Cell. 181, 1–10. April 16, 2020, DOI: 10.1016/j.cell.2020.02.052; Zhou, P et al. Nature.579, 270–273 (2020). DOI: 10.1038/s41586-020-2012-7; Xiaoqiang Chai et al. bioRxiv 2020.02.03.931766, DOI: 10.1101/2020.02.03.931766; Tikellis, Chris, and M C Thomas. Int J Pep. vol. 2012 (2012): 256294. doi:10.1155/2012/256294; Wrap et al. Science, 13 Mar 2020:Vol. 367, Issue 6483, pp. 1260-1263. DOI: 10.1126/science.abb2507;