Enhancement of immunodeficiency virus-specific immune responses in DNA-immunized rhesus macaques.

In contrast to results obtained with plasmid DNA vectors encoding antigens from viruses such as influenza and hepatitis B, plasmids coding for antigens from primate immunodeficiency viruses have elicited relatively weak antibody responses following gene gun-mediated DNA immunization of rhesus monkeys. In an effort to augment these responses, the importance of the immunization schedule was investigated, as well as the possible synergy that might result from boosting gene gun-primed animals with other routes of immunization. Here we demonstrate that endpoint gp120-specific antibody titers can be enhanced as much as tenfold by reducing the number of immunizations and lengthening the resting period between immunizations. In addition, boosting gene gun-primed animals with either recombinant subunits or gp120-expressing vaccinia recombinants resulted in synergistic responses.