SARS-CoV-2 infection in human ACE2-expressing transgenic mice (Winkler et al., 2020), ferrets (Blanco-Melo et al., 2020), Syrian golden hamsters (Chan et al., 2020) and non-human primates (Rockx et al., 2020) can mimic the pathology, immune response and clinical manifestations of COVID-19 patients. The gene discussed is ACE2; the disease is COVID-19.