These animals are permissive to infection by some SARS-CoV-2 variants (including B.1.1.7, B.1.1.28, and B.1.351) or mouse-adapted strains (15–17) that encode an N501Y mutation, which enables engagement of endogenous murine angiotensin converting enzyme 2 (ACE2) (18). The gene discussed is ACE2; the disease is infection.