These pseudoviruses were based on env sequences observed after HIV-1 infection and represent infection in the absence of selection pressure (placebo arms, HVTN 703/HPTN 081 and HVTN 704/HPTN 085) or breakthrough infections in the presence of VRC01 (VRC01 arm of HVTN703/HPTN 081 trial). Here, ERVW-1 is linked to HIV-1 infection.