At that time, it was found that the protein S (spike) on the surface of the virus allowed the microorganism to enter the host’s lung using ACE2 as a receptor in the surface of type II pneumocytes (Hamming et al., 2004; Kuba et al., 2005) and downregulation of ACE2 expression was observed using both experimental SARS-CoV infections of wildtype mice in vivo in the lungs and recombinant SARS-CoV surface-spike protein binding to ACE2 in cell lines (Kuba et al., 2005). The gene discussed is ACE2; the disease is infection.