BACKGROUNDRV144 is the only preventive HIV vaccine regimen demonstrating efficacy in humans. Attempting to build upon RV144 immune responses, we conducted a phase 1, multicenter, randomized, double-blind trial to assess the safety and immunogenicity of regimens substituting the DNA-HIV-PT123 (DNA) vaccine for ALVAC-HIV in different sequences or combinations with AIDSVAX B/E (protein).METHODSOne hundred and four HIV-uninfected participants were randomized to 4 treatment groups (T1, T2, T3, and T4) and received intramuscular injections at 0, 1, 3, and 6 months (M): T1 received protein at M0 and M1 and DNA at M3 and M6; T2 received DNA at M0 and M1 and protein at M3 and M6; T3 received DNA at M0, M1, M3, and M6 with protein coadministered at M3 and M6; and T4 received protein and DNA coadministered at each vaccination visit.RESULTSAll regimens were well tolerated. Antibodies binding to gp120 and V1V2 scaffold were observed in 95%-100% of participants in T3 and T4, two weeks after final vaccination at high magnitude. While IgG3 responses were highest in T3, a lower IgA/IgG ratio was observed in T4. Binding antibodies persisted at 12 months in 35%-100% of participants. Antibody-dependent cell-mediated cytotoxicity and tier 1 neutralizing-antibody responses had higher response rates for T3 and T4, respectively. CD4+ T cell responses were detectable in all treatment groups (32%-64%) without appreciable CD8+ T cell responses.CONCLUSIONThe DNA/protein combination regimens induced high-magnitude and long-lasting HIV V1V2-binding antibody responses, and early coadministration of the 2 vaccines led to a more rapid induction of these potentially protective responses.TRIAL REGISTRATIONClinicalTrials.gov NCT02207920.FUNDINGNational Institute of Allergy and Infectious Diseases (NIAID) grants UM1 AI068614, UM1 AI068635, UM1 AI068618, UM1 AI069511, UM1 AI069470, UM1 AI069534, P30 AI450008, UM1 AI069439, UM1 AI069481, and UM1 AI069496; the National Center for Advancing Translational Sciences, NIH (grant UL1TR001873); and the Bill & Melinda Gates Foundation (grant OPP52845).