Analysis of the neutralization breadth of the anti-V3 antibody F425-B4e8 and re-assessment of its epitope fine specificity by scanning mutagenesis

Virology. 2007 Aug 1;364(2):441-53. doi: 10.1016/j.virol.2007.03.007. Epub 2007 Apr 6.


The identification of cross-neutralizing antibodies to HIV-1 is important for designing antigens aimed at eliciting similar antibodies upon immunization. The monoclonal antibody (mAb) F425-B4e8 had been suggested previously to bind an epitope at the base of V3 and shown to neutralize two primary HIV isolates. Here, we have assessed the neutralization breadth of mAb F425-B4e8 using a 40-member panel of primary HIV-1 and determined the epitope specificity of the mAb. The antibody was able to neutralize 8 clade B viruses (n=16), 1 clade C virus (n=11), and 2 clade D viruses (n=6), thus placing it among the more broadly neutralizing anti-V3 antibodies described so far. Contrary to an initial report, results from our scanning mutagenesis of the V3 region suggest that mAb F425-B4e8 interacts primarily with the crown/tip of V3, notably Ile(309), Arg(315), and Phe(317). Despite the somewhat limited neutralization breadth of mAb F425-B4e8, the results presented here, along with analyses from other cross-neutralizing anti-V3 mAbs, may facilitate the template-based design of antigens that target V3 and permit neutralization of HIV-1 strains in which the V3 region is accessible to antibodies.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Amino Acid Substitution
  • Antibodies, Monoclonal
  • Cell Line
  • Cross Reactions
  • Epitope Mapping
  • Epitopes / chemistry
  • Epitopes / genetics
  • HIV Antibodies*
  • HIV Envelope Protein gp120 / chemistry
  • HIV Envelope Protein gp120 / genetics*
  • HIV Envelope Protein gp120 / immunology*
  • HIV-1 / classification
  • HIV-1 / genetics*
  • HIV-1 / immunology*
  • HIV-1 / pathogenicity
  • Humans
  • In Vitro Techniques
  • Models, Molecular
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Neutralization Tests
  • Peptide Fragments / chemistry
  • Peptide Fragments / genetics*
  • Peptide Fragments / immunology*
  • Virulence / genetics


  • Antibodies, Monoclonal
  • Epitopes
  • HIV Antibodies
  • HIV Envelope Protein gp120
  • HIV envelope protein gp120 (305-321)
  • Peptide Fragments