Infection did not occur when cells were infected with viruses without envelopes (Env-) or with viruses pseudotyped with HIV envelope (JR-FL), which requires CCR5 for viral entry (Supplementary Table S1), indicating the specificity of SARS-CoV-2 spike-protein-mediated entry of pseudotyped SARS-CoV-2 viruses. Here, ERVW-1 is linked to infection.