What are the receptors used by SARS-CoV-2 for cell entry?
SARS-CoV-2 binds to ACE2 via its spike protein to enter human cells8. Cell entry is facilitated by the host serine protease TMPRSS2 that cleaves the spike protein into S1 and S2 fragments, thus enabling cellular membrane fusion (Figure 1 ).9 ACE2 is highly expressed in the lungs, small intestine, kidney and heart, but not in innate and adaptive immune cells.10-13 SARS-CoV-2 also binds to CD147 (known as basigin or extracellular matrix metalloproteinase inducer), which is expressed in human airway and kidney epithelium, as well as in innate cells and lymphocytes14. Receptors reported for other coronaviruses, such as CD26, aminopeptidase N and glutamyl aminopeptidase could be utilized by SARS-CoV-2 for cell invasion.13,15,16