SARS-CoV-2 is the causative virus for COVID-19. Cell entry of SARS-CoV-2 depends on angiotensin-converting enzyme II (ACE2), which is a membrane-associated zinc peptidase, and transmembrane serine protease 2, which is a cellular serine protease (Zhou et al., 2020b; Hoffmann et al., 2020; Hirano and Murakami, 2020). ACE2 is homologous with, but acts antagonistically to, angiotensin-converting enzyme (ACE) and has the critical function of protecting the lungs from severe acute injury (Imai et al., 2005).
