IMMUNOGENICITY OF SYNTHETIC HIV-1 GP120 V3-LOOP PEPTIDE-CONJUGATE IMMUNOGENS

A successful prophylactic human immunodeficiency virus type 1 (HIV-1) vaccine must elicit an immune response that will prevent establishment of the persistent viral infection. The only response shown to be effe ctive in this regard is virus-neutralizing antibody directed against t he viral gp120 hypervariable V3-loop region. Conjugate immunogens, con taining cyclic peptides representing the V3 determinant covalently bou nd to a carrier protein, were capable of eliciting virus-neutralizing antibodies. The consistency of the response was related to peptide siz e. The smaller cyclic peptides, expressing relatively conserved sequen ces from the V3-loop apex, were poor inducers of neutralizing activity . In contrast, the largest cyclic peptides mediated neutralizing respo nses that were similar to those observed and previously reported for i ntact gp120 immunogens. A cyclic synthetic peptide expressing most of the prototypic HIV-1 MN variant V3 determinant warrants further study as a potentially effective vaccine immunogen.