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BACKGROUNDHVTN 098, a randomized, double-blind, placebo-controlled trial, evaluated the safety, tolerability, and immunogenicity of PENNVAX-GP HIV DNA vaccine, administered with or without plasmid IL-12 (pIL-12), via intradermal (ID) or intramuscular (IM) electroporation (EP) in healthy, HIV-uninfected adults. The study tested whether PENNVAX-GP delivered via ID/EP at one-fifth the dose could elicit equivalent immune responses to delivery via IM/EP and whether inclusion of pIL-12 provided additional benefit.METHODSParticipants received DNA encoding HIV-1 env/gag/pol in 3 groups: 1.6 mg ID (ID no IL-12 group, n = 20), 1.6 mg ID + 0.4 mg pIL-12 (ID + IL-12 group, n = 30), 8 mg IM + 1 mg pIL-12 (IM + IL-12 group, n = 30), or placebo (n = 9) via EP at 0, 1, 3, and 6 months. Results of cellular and humoral immunogenicity assessments are reported.RESULTSFollowing vaccination, the frequency of responders (response rate) to any HIV protein based on CD4+ T cells expressing IFN-γ or IL-2 was 96% for both the ID + IL-12 and IM + IL-12 groups; CD8+ T cell response rates were 64% and 44%, respectively. For ID delivery, the inclusion of pIL-12 increased CD4+ T cell response rate from 56% to 96%. The frequency of responders was similar (≥90%) for IgG binding antibody to gp140 consensus Env across all groups, but the magnitude was higher in the ID + IL-12 group compared with the IM + IL-12 group.CONCLUSIONPENNVAX-GP DNA induced robust cellular and humoral immune responses, demonstrating that immunogenicity of DNA vaccines can be enhanced by EP route and inclusion of pIL-12. ID/EP was dose sparing, inducing equivalent, or in some aspects superior, immune responses compared with IM/EP.TRIAL REGISTRATIONClinicalTrials.gov NCT02431767.FUNDINGThis work was supported by National Institute of Allergy and Infectious Diseases (NIAID), U.S. Public Health Service grants, an HIV Vaccine Design and Development Team contract, Integrated Preclinical/Clinical AIDS Vaccine Development Program, and an NIH award.