A new multi-clade DNA prime/recombinant MVA boost vaccine induces broad and high levels of HIV-1-specific CD8+ T-cell and humoral responses in mice

The results presented here are from the preclinical evaluation in BALB/c mice of a DNA prime/modified vaccinia virus Ankara ( MVA) boost multi-gene multi-subtype human immunodeficiency virus-1(HIV-1) vaccine intended for use in humans. The plasmid DNA vaccine was delivered intradermally using a Biojector, and the MVA was delivered intramuscularly by needle. This combination of recombinant DNA and MVA proved to induce extraordinarily strong cellular responses, with more than 80% of the CD8(+) T cells specific for HIV-1 antigens. Furthermore, we show that the DNA priming increases the number of T-cell epitopes recognized after the MVA boost. In the prime/boost-immunized animals, a significant proportion of CD8+ T cells were stained positive for both interferon-gamma(IFN-gamma)and interleukin- 2 ( IL-2), a feature that has been associated with control of HIV-1 infection in long-term nonprogressors. The HIV-1-specific antibody levels were moderate after the plasmid DNA immunizations but increased dramatically after the MVA boost. Although the initial injection of MVA induced significant levels of vaccinianeutralizing antibodies, the HIV-specific responses were still significantly boosted by the second MVA immunization. The results from this study demonstrate the potency of this combination of DNA plasmids and MVA construct to induce broad and high levels of immune responses against several HIV-1 proteins of different subtypes.