INDUCTION OF HIV-1 IIIB NEUTRALIZING ANTIBODIES IN BALB C MICE BY A CHIMERIC PEPTIDE CONSISTING OF A T-HELPER CELL EPITOPE OF SEMLIKI-FOREST-VIRUS AND A B-CELL EPITOPE OF HIV/

A colinearly synthesized peptide consisting of a H-2(d) restricted T-h elper cell epitope of Semliki Forest virus (SFV) ann triple repents of sequence GPGRAF, derived from the V3 domain of HN-I strains, was used to immunize BALB/c (H-2(d)) mice. Pepscan analysis of sera from pepti de-immunized mice revealed that the chimaeric peptide GREKFTIRPHYGKEIG PGRAFGPGRAFGPGRAF contains three distinct antibody-reactive sequences GREKFTIR, PHYGKEI and GPGRAF. The chimaeric peptide evoked HN-I IIIb n eutralizing antibodies in serum as measured in vitro by reduction of s yncytia formation and reduction of p24 production as well. So, the T-h elper cell epitope of SFV provided help to a small linear neutralizati on epitope of HIV-1 strains. Interestingly; the T-helper cell epitope alone might induce antibodies cross-reactive with HN-I IIIb specific p eptide GPGRAFVTIGK which shows some homology (residues underlined) wit h the antibody-reactive sequence GREKTIR of SFV. (C) 1998 Elsevier Sci ence Ltd. All rights reserved.