Conformational constraints imposed on a pan-neutralizing HIV-1 antibody epitope result in increased antigenicity but not neutralizing response

Vaccine. 2005 Feb 18;23(13):1559-73. doi: 10.1016/j.vaccine.2004.09.037.

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.

MeSH terms

  • Animals
  • Binding Sites, Antibody
  • Cells, Cultured
  • Cross Reactions
  • Epitopes / chemistry*
  • Epitopes / genetics
  • Epitopes / immunology*
  • Epitopes / isolation & purification
  • HIV Antibodies / biosynthesis*
  • HIV Antibodies / genetics
  • HIV Antibodies / metabolism
  • HIV Antibodies / pharmacology*
  • HIV Envelope Protein gp160 / chemistry
  • HIV Envelope Protein gp160 / genetics
  • HIV Envelope Protein gp160 / immunology
  • HIV-1 / genetics
  • HIV-1 / growth & development
  • HIV-1 / immunology*
  • HLA-DR Antigens / genetics
  • HLA-DR Antigens / immunology
  • HLA-DR Antigens / metabolism
  • Humans
  • Immunoglobulin Fab Fragments / biosynthesis
  • Immunoglobulin Fab Fragments / metabolism
  • Neutralization Tests / methods
  • Peptide Fragments / metabolism
  • Peptide Fragments / pharmacology
  • Protein Conformation
  • Protein Structure, Secondary
  • Rabbits

Substances

  • Epitopes
  • HIV Antibodies
  • HIV Envelope Protein gp160
  • HLA-DR Antigens
  • Immunoglobulin Fab Fragments
  • Peptide Fragments