As SARS-CoV-2 is unable to engage mouse ACE2 as a receptor for infection, mice expressing hACE2 have been developed and widely used for COVID-19 research (Bao et al., 2020; Jiang et al., 2020; Wan et al., 2020; Dong et al., 2022; Sefik et al., 2022). The gene discussed is ACE2; the disease is infection.