CRISPR/cas9 mediated recombination inserted a CAG promoter, floxed stop cassette, modified human ACE2 cDNA, woodchuck hepatitis virus post-transcriptional regulatory element, simian virus 40 polyA sequence, loxP site, and an FRT-flanked PGK-neo cassette. The human ACE2 cDNA was modified to use the mouse Ace2 signal peptide and codon optimized for mouse. (J:315719)