The S protein is the primary target for neutralizing antibodies to prevent viral infection, since SARS-CoV-2-RBD-specific IgG antibodies effectively block SARS-CoV-2-RBD binding to the host cell receptor human angiotensin-converting enzyme 2 (ACE2), a zinc metalloprotease that is also called peptidyl-dipeptidase (Turner et al., 2002; Chen et al., 2020). This evidence concerns the gene ACE2 and viral infectious disease.