Cross-reactive potential of rabbit antibodies raised against a cyclic peptide representing a chimeric V3 loop of HIV-1 gp120 studied by biosensor technique and ELISA.

Rabbit antibodies were induced against a free cyclic peptide representing the chimeric sequence of a consensus V3 loop of HIV-1 gp120. The reactivity of these antibodies was tested in a biosensor system (BIAcore, Pharmacia AB, Uppsala, Sweden) and in ELISA with the peptide immunogen in its cyclic and linear forms, as well as with peptides corresponding to the V3 region of different HIV-1 variants. The antibodies reacted with all the peptides tested both in ELISA and in biosensor assays and recognized the cyclic form of the chimeric peptide better than the linear form. Although antibodies raised against the V3 region of particular HIV-1 variants cross-react with other HIV-1 strains, it seems that the use of a chimeric peptide as immunogen improved the cross-reactivity spectrum of recognition of the antibodies. The anti-V3 antibodies were also tested for their ability to neutralize in vitro four HIV-1 laboratory strains. Only the HIVMN variant was found to be neutralized. Compared to conventional solid phase immunoassays, the BIAcore presents several advantages for measuring the differential reactivity of peptide analogues. In view of their broadly cross-reactive potential, antibodies raised against a consensus sequence should be useful in immunodiagnosis of viral antigenic variants.