ERVW-1 and HIV-1 infection: A hazard ratio (vaccine/placebo) of HIV-1 infection was estimated by stratifying breakthrough sequences based on their distance to the subtype B insert calculated for three sets of Env-gp120 sites: i) all Env-gp120 sites aligned with confidence (n = 432, 64.6% of sites); ii) CD4bs antibody contact sites (n = 93); and iii) sites corresponding to the 4 linear signature regions overlapping the CD4bs where significant sieve effects were found (n = 54; Table 1).