ERVW-1 and infection: Human 293T cells have been reported to be less susceptible to infection with SARS-CoV-2 [3,4,10,11,80], which is consistent with our present results in Figure 1A. To confirm whether the luciferase activity in our infectivity assay was generated by viral envelope-mediated infection, we conducted neutralization experiments using antibodies against the envelope glycoproteins of SARS-CoV-2 and Ebola virus.