In detail, eexperimental infections and binding-affinity assays between the “receptor binding domain” (RBD) of the SARS-CoV-2 spike (S) protein and its receptor, angiotensin-converting enzyme-2 (ACE-2), demonstrate that SARS-CoV-2 has a wide host range because of the high similarity of this protein among difference species [19,20]. The gene discussed is ACE2; the disease is infection.