Focusing the immune response on the V3 loop, a neutralizing epitope of the HIV-1 gp120 envelope

Virology. 2008 Mar 15;372(2):233-46. doi: 10.1016/j.virol.2007.09.024. Epub 2007 Dec 3.


Rabbits were immunized with a novel regimen designed to focus the immune response on a single neutralizing epitope of HIV-1 gp120 and thereby preferentially induce neutralizing antibodies (Abs). Animals were primed with gp120 DNA from a clade A Env bearing the GPGR V3 motif and/or a clade C Env bearing the GPGQ V3 motif, and boosted with one or more fusion proteins containing V3 sequences from clades A, B and/or C. Immune sera neutralized three of four Tier 1 primary isolates, including strains heterologous to the immunizing strains, and potent cross-clade-neutralizing activity was demonstrated against V3 chimeric pseudoviruses carrying in a Tier 1 Env, the consensus V3 sequences from clades A1, AG, B, AE, or F. The broadest and most potent neutralizing responses were elicited with the clade C gp120 DNA and a combination of V3-fusion proteins from clades A, B and C. Neutralizing activity was primarily due to V3-specific Abs. The results demonstrate that the immune response can be focused on a neutralizing epitope and show that the anti-V3 Abs induced recognize a diverse set of V3 loops.

Publication types

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

MeSH terms

  • AIDS Vaccines / immunology*
  • Amino Acid Sequence
  • Animals
  • Antibodies, Viral / immunology
  • Enzyme-Linked Immunosorbent Assay
  • Epitopes / immunology*
  • HIV Envelope Protein gp120 / chemistry*
  • HIV Envelope Protein gp120 / immunology*
  • Neutralization Tests
  • Peptide Fragments / chemistry*
  • Peptide Fragments / immunology*
  • Rabbits


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