ACE2 and severe acute respiratory syndrome: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its cousin, SARS-CoV, which was responsible for the SARS epidemic in 2002/2003, use the cellular carboxypeptidase angiotensin-converting enzyme 2 (ACE2) as receptor for entry.4,5 Binding of the viral spike protein (S) to ACE2 is essential for SARS-CoV and SARS-CoV-2 entry into target cells, although engaging other cellular factors like heparan sulfate proteoglycans can increase ACE2-dependent entry.