ACE2 and infection: After validation of exogenous ACE2 expression in BHK-21 and HEK293 cells by western blot (Supplementary Figure S1B), the infectivity assay were performed and showed that pseudovirus variants have significantly higher luciferase activities compared to the Wuhan strain (Supplementary Figure S1C), suggesting other variant strains exhibited more efficient ACE2-mediated infection than the wild type Wuhan strain as previously described (Arora et al., 2021; Kuzmina et al., 2021; Hoffmann et al., 2022).