In the case of SARS‐CoV, ACE2 binding was found to be a critical determinant for the range of hosts the virus can infect, and key amino acid residues in the RBD were identified to be essential for ACE2‐mediated SARS‐ CoV infection and adaptation to humans (Li et al., 2005, 2006). This evidence concerns the gene ACE2 and severe acute respiratory syndrome.