A DNA/MVA-based candidate human immunodeficiency virus vaccine for Kenya induces multi-specific T cell responses in rhesus macaques.

The minimum requirement for candidate human immunodeficiency virus (HIV) vaccines to enter clinical evaluation in humans should be their demonstrable immunogenicity in non-human primates: induction of antibodies neutralizing primary HIV isolates or elicitation of broad T cell-mediated immune responses. Here, we showed in rhesus macaques that the very same vaccines that had entered clinical trials in Oxford and Nairobi, plasmid pTHr.HIVA DNA and recombinant modified vaccinia virus Ankara MVA.HIVA in a prime-boost protocol (Hanke & McMichael, Nature Medicine 6, 951-955, 2000), induced cellular immune responses specific for multiple HIV-derived epitopes. This was demonstrated by using the intracellular cytokine staining and ELISPOT assays detecting interferon-gamma and pools of peptides employed in the clinical studies. These results have both boosted our expectations for the performance of these vaccines in humans and increased our confidence about the choice of these assays as the primary readouts in the on-going human trials.