title: Recombinant antibodies with conformationally constrained HIV type 1 epitope inserts elicit glycoprotein 160-specific antibody responses in vivo.
abstract: Although neutralizing epitopes have been identified on the HIV-1 gp120/gp41 envelope complex, efforts to exploit this information through the construction of synthetic peptide vaccines have been largely unsuccessful. Unfortunately, synthetic peptides tend to be poorly immunogenic, and most often lack the conformational characteristics of the corresponding epitope in the native protein. In an effort to circumvent these difficulties, we have utilized an anti-class II MHC antibody as a molecular scaffold for the construction of two conformationally constrained neutralizing HIV-1 epitopes. Previously we demonstrated that anti-class II MHC antibodies can function as vectors for the induction of adjuvant-independent antibody responses to incorporated epitopes. In this instance, one epitope, IHIGPGRAFYT, is the crown of the V3 loop from gp120, and the other, ELDKWAS, is a neutralizing epitope from gp41. The insertion of these epitopes into a specific loop region of the immunoglobulin heavy chain FR3 was found to preserve the anti-class II MHC-binding activity of these recombinant antibodies, and the inserts were recognized by epitope specific monoclonal antibodies. When utilized as immunogens, each of these epitope insertion antibodies was able to induce high-titer anti-HIV-1 gp160 responses in guinea pigs. These responses were conformation specific in that the anti-gp160 binding was not inhibited by the synthetic peptide corresponding to the epitope in question. These data demonstrate the potential to construct conformationally constrained HIV-1 epitope immunogens, and thus establish an alternative approach to the design of an effective HIV-1 subunit vaccine.
authors.affiliation: Department of Immunology, University of Toronto, Ontario, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Cook
authors.forename: B H
authors.initials: BH
authors.lastname: Barber
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D002460:Cell Line; D002522:Chlorocebus aethiops; D003429:Cross Reactions; D000939:Epitopes / Q000276:immunology*; D005260:Female; D006168:Guinea Pigs; D015483:HIV Antibodies / Q000276:immunology*; D019302:HIV Envelope Protein gp160 / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D011487:Protein Conformation; D011995:Recombination, Genetic; D014709:Vero Cells
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D015483:HIV Antibodies; D019302:HIV Envelope Protein gp160