What are the main structural differences of SARS-CoV-1 and -2?
The spike protein of SARS-CoV-2 has a receptor-binding domain that binds ACE2 with higher affinity than SARS-CoV.8 In addition, the SARS-CoV-2 spike protein harbors a polybasic furin cleavage site (PRRAR) with an insertion of 4 amino acid residues, which is distinct from that found in SARS-CoV and other SARS-like viruses. This allows effective cleavage by furin and other proteases and determines viral infectivity and host range.6