SARS-CoV-2 enters host cells by membrane fusion dependent on the interaction between viral spike protein and cell surface protein ACE2.33 During subsequent viral replication, the infected cells can form syncytia mediated by cell surface expression of the spike protein.22 We found that, at 20 h post infection, substantial HeLa-ACE2 cells were fused to form multinucleated cells (Supplementary Fig. 1, b). The gene discussed is ACE2; the disease is infection.