Immunogenic combinations of HIV-1 B- and heterologous T-cell epitopes.

Peptides were synthesized which combined HIV-1 B-epitopes from gp41, p34pol and heterologous T-cell epitopes from hepatitis B virus (HBV) core or tetanus toxoid. Mixtures of these composite peptides and peptides representing single HIV-1 B-epitopes were used to immunize rabbits in an adjuvant-free immunization regimen. Fusion to T-cell epitopes made the HIV-1 B-epitopes immunogenic and high titers of anti-HIV-1 antibodies were reached. Efficient antibody response against an immunorecessive HIV-1 B-epitope from p34 pol introduced as a B+T-composite also developed in rabbits pre-immunized by composites of the same T-cell epitopes but with a B-epitope from gp41. Fusion changed the fine antigenicity of the epitopes, but at least part of the antibodies against gp41-containing B+T composites recognized whole viral gp160. Composite peptides stimulated T-cells in the majority of the immunized animals.