title: Conformational constraints imposed on a pan-neutralizing HIV-1 antibody epitope result in increased antigenicity but not neutralizing response.
abstract: 2F5 is one of the few broadly neutralizing monoclonal antibodies against type 1 Human Immunodeficiency Virus (HIV-1). It recognizes the amino acid sequence ELDKWAS in gp41. We have previously identified a number of immunotargeting 2F5-reactive candidate immunogens. Three of them (designated H-BT1-3) have the ELDKWAS sequence constrained at beta-turn sites within the immunoglobulin heavy chain. Two others (L-CT and L-CTx3) have the sequence attached at the C-terminus of the immunoglobulin light chain with minimal conformational constraints. In the present investigation, the H-BTs were found to bind 2F5 with up to 10-fold higher affinities than their unconstrained counterpart. When used as immunogens, immunogen-specific antibodies were induced with or without adjuvant, confirming the immunotargeting potential of these immunogen constructs. While HIV-1 gp160 cross-reactive antibodies were induced, virus neutralization was not detected. Thus, factors other than 2F5 binding affinity may have a critical role to play in the design of a 2F5-based vaccine.
authors.affiliation: Department of Immunology, University of Toronto, Toronto, Ontario, Canada M5S 1A8.
authors.forename: Jason
authors.initials: J
authors.lastname: Ho
authors.forename: Robert A
authors.initials: RA
authors.lastname: Uger
authors.forename: Michael B
authors.initials: MB
authors.lastname: Zwick
authors.forename: Mark A
authors.initials: MA
authors.lastname: Luscher
authors.forename: Brian H
authors.initials: BH
authors.lastname: Barber
authors.forename: Kelly S
authors.initials: KS
authors.lastname: MacDonald
mesh_terms: D000818:Animals; D001666:Binding Sites, Antibody; D002478:Cells, Cultured; D003429:Cross Reactions; D000939:Epitopes / Q000737:chemistry* / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D015483:HIV Antibodies / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D019302:HIV Envelope Protein gp160 / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D015497:HIV-1 / Q000235:genetics / Q000254:growth & development / Q000276:immunology*; D006684:HLA-DR Antigens / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000096:biosynthesis / Q000378:metabolism; D009500:Neutralization Tests / Q000379:methods; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011817:Rabbits
chemical_list: D000939:Epitopes; D015483:HIV Antibodies; D019302:HIV Envelope Protein gp160; D006684:HLA-DR Antigens; D007140:Immunoglobulin Fab Fragments; D010446:Peptide Fragments