To monitor and visualize virus assembly and release, ie. only the late steps of HIV-1 infection cycle, avoiding re-infection and entry, we used a single round virus, VSV-G pseudotyped HIV-1(i)GFP depleted from its Env glycoproteins (pVSV-G + pCMV-NL4.3(i)GFPΔEnv) for T cell infection (described in Supplementary Fig. 1). Here, ERVW-1 is linked to infection.