Transgenic mouse expressing human angiotensin converting enzyme 2 (ACE2), the receptor for SARS-CoV-2,24 under the control of the epithelial cell cytokeratin-18 promoter, represents a model of severe COVID-19.25,26 However, the artificial expression of human ACE2 does not faithfully recapitulate human ACE2 expression and animals suffer from severe SARS-CoV-2-induced encephalitis, a cause of death not observed in humans. This evidence concerns the gene ACE2 and encephalitis.