In an effort to develop a more effective DNA immunization strategy for HIV, we synthesized an HIV-2 env DNA vaccine and delivered it in a novel polycationic adjuvant formulation that forms nanoparticles in solution and enhances protein expression. The polycationic adjuvant contained imidazole moieties to facilitate endosomal escape. Nanoparticles containing the DNA vaccine plasmid were formed by electrostatic condensation with the polycationic adjuvant. We hypothesized that this formulation would improve immune responses to the gp140 env gene from HIV-2(UC2) by increasing the level of expressed antigen. We found that the nanoparticles were superior at inducing high levels of systemic antibody responses compared to naked DNA when delivered by the intradermal route in BALB/c mice. In addition, the nanoparticles induced higher levels of IgM, IgG, and IgA antibodies. These results suggest that nanoparticles may be an important adjuvant formulation to improve the effectiveness of genetic immunization and rationalize its use in the evaluation of vaccine candidates in non-human primate models for AIDS.