[Composition of HIV-1 B-epitopes and heterologous T-cell epitopes. II. Combined analysis of immunogenicity of composite peptides in rabbits].

Rabbits were immunized with a mixture of linear cojoined peptides (composites) combining an immunodominant B-cell epitope from gp41 of HIV-1 (amino acids 593-604) and a heterogeneous T-cell epitope from tetanus toxoid or hepatitis B core antigen. HIV-1 B-epitope in the context of the composites induced HIV-1 specific antibody response, while no antibodies were produced in response to the peptide representing single HIV-1 B-epitope. Competition ELISA and ELISA of HIV-1 peptide omission analogous demonstrated that immunization induced antibodies of the correct specificity. T-Cell epitopic components also elicited potent antibody production. T-Cell epitopes appeared to be immunodominant. However, HIV-1 specific antibody response was not suppressed, on the contrary, antibody response against HIV-1 B- and heterologous T-cell epitopes developed in parallel. Cellular responses against composite peptides and/or their components were induced in all animals. The ability to develop cellular response against T-cell epitopes from the composites determined the efficacy of humoral response against the composites including HIV-1 specific one. Animals with strong cellular responses rapidly developed maximum antipeptide antibody titers. The immunization results imply that colinear fusion of B- and T-cell epitopes yielded bivalent multiepitopic products in which the immunological properties of the individual components were maintained and desired immunogenic properties were obtained. Immunogenicity of the composite peptides corresponded to that expected from the study of the composite antigenic properties.