Coronavirus spike (S) glycoprotein trimers promote entry into cells and are the main targets of the humoral immune response. We demonstrated that ACE2 is a functional entry receptor for this novel coronavirus and that the receptorbinding domains of SARS-CoV-2 S and SARS-CoV S bind with similar affinities to ACE2, which correlates with the efficient spread of SARS-CoV-2 among humans.
