Macrophage inflammatory protein-1α (MIP-1α) expression plasmid enhances DNA vaccine-induced immune response against HIV-1

CD8(+) cell-secreted CC-chemokines, MIP-1 alpha, and MIP-beta have recently been identified as factors which suppress HIV. In this study we co-inoculated MIP-1 alpha expression plasmid with a DNA vaccine constructed from HIV-1 pCMV160IIIB and pcREV, and evaluated the effect of the adjuvant on HIV-specific immune responses following intramuscular and intranasal immunization. The levels of both cytotoxic T lymphocyte (CTL) activity and DTH showed that HIV-specific cell-mediated immunity (CMI) was significantly enhanced by co-inoculation of the MIP-1 alpha expression plasmid with the DNA vaccine compared with inoculation of the DNA vaccine alone. The HIV-specific serum IgG1/IgG2a ratio was significantly lowered when the plasmid was co-inoculated in both intramuscular and intranasal routes, suggesting a strong elicitation of the T helper (Th) 1-type response. When the MIP-1 alpha expression plasmid was inoculated intramuscularly with the DNA vaccine, an infiltration of mononuclear cells was observed at the injection site. After intranasal administration, the level of mucosal secretory IgA antibody was markedly enhanced. These findings demonstrate that MIP-1 alpha expression plasmid inoculated together with DNA vaccine acts as a strong adjuvant for eliciting Th1-derived immunity.