ACE2 and infection: Plaque assay showed significantly higher number of infectious virus particles in the supernatant of ACE2+ corpus cells, indicating productive virus replication (Figure 3F), yet the assay also showed some infectious virus in the supernatant of the wild-type (WT) corpus cells, as was already observed in Figure 1E. We suspected that these were residual virus particles from the initial high infection dose that generally escape washing steps.