ACE2 and infection: Unlike WT A549 cells stably transduced with ACE2 and TMPRSS2, in which SARS-CoV-2 can be detected 24 hours after infection, no SARS-CoV-2 was detected in THP-1–derived macrophages (61), whether parental or with a KO of OAS1, OAS2, or RNase L (Fig. 2, G and H, and fig.