Linear fusion of HIV-1 B- and heterologous T-cell epitopes. I. Antigenic properties of HIV-1 B-cell epitope are preserved

Peptides were synthesized combining an immunodominant B-cell epitope from gp41 of HIV-1 with heterogenous T-cell epitopes from tetanus toxoid or hepatitis B core antigen with no spacer bridge between epitopes. The antigenic properties of the B-cell epitope within the composites were evaluated. The majority of the rabbit sera against the immunodominant B-cell epitope from gp41 recognized the B-cell epitope of gp41 and its composites as closely related structures. The comparative study of the composite peptide recognition by HIV-1 antibody positive human sera revealed that 82% of them similarly recognized a single gp41 epitope and its composites. The difference in the affinity values for the B-cell epitope from gp41 and its composites was less prominent than the difference between the affinity values for the single peptides derived from the immunodominant region of gp41. This indicates that the B-cell epitope from gp41 was not changed by fusion to heterologous amino acid sequences. The evaluation of the immunogenicity of the composites would reveal whether the antigenic characteristics can be of help in the selection of the components of multivalent peptide vaccines.