Finally, to test the role of ACE2 in AT1, AT2, and bronchiolar epithelial cell infection in the lung, we examined SARS-CoV-2 infection of ShhCre; hACE2fl/y animals in which Cre is active in all lower respiratory and gastrointestinal epithelium ([45]; S4 and S5 Figs). This evidence concerns the gene ACE2 and infection.