We first produced GFP-expressing HIV-1 pseudovirions bearing the individual Env of HIV-1 by co-transfecting HEK293T cells with pLenti-Puro-GFP, Gag-Pol Δ8.2 and HIV-1 Env of interest and analyzed the pseudoviral infection efficiency in U87-derived cell lines by flow cytometry. Here, ERVW-1 is linked to infection.