ACE2 and infection: Previous researches demonstrated that mild infection symptoms and few SARS-CoV-2 viral particles were detected in brains of mice models expressing hACE2 when promoters were exogenous or endogenous murine ACE2 or cytomegalovirus (CMV).137,244–246 In these models, the evidence for the presence of SARS-CoV-2 mostly based on PCR,247,248 but did not prove through in situ hybridization or immunocytochemistry.