ACE2 and infection: The other models, mouse ACE2 promoter with human ACE2 coding sequence [112], endogenous mouse ACE2 promoter model [113], and the ferret model [114], would not be useful in the study of lung clinical symptoms as they showed no or mild symptoms after infection with SARS-CoV-2 compared to the hACE2 transgenic mouse, Syrian hamster, and NHP models.