Differential role of V3-specific antibodies in neutralization assays involving primary and laboratory-adapted isolates of HIV type 1

AIDS Res Hum Retroviruses. 1995 Nov;11(11):1379-91. doi: 10.1089/aid.1995.11.1379.


To identify epitopes important in neutralizing primary HIV-1 isolates, we have selectively depleted HIV-1 sera of antibodies specific for the third hypervariable region (V3) of the HIV-1 envelope glycoprotein gp120, and then assessed the functional consequences of such depletion in neutralization assays. The nucleotide sequence of the V3 loop region from HIV-1 PBMC DNA was determined for three HIV-1-infected patients, corresponding peptides were synthesized, and then subsequently used for V3 depletion of the patient sera. Depletion using a single clade B V3 peptide was capable of depleting > 98% of binding antibodies to multiple clade B V3 peptides, including those with changes within the GPGX tip of the loop. Depleted and undepleted sera were studied for their ability to neutralize both laboratory-adapted HIV-1MN and two primary HIV-1 isolates with known V3 sequences, using a viral infectivity reduction assay. While the majority of HIV-1MN neutralization was lost on V3 depletion, the loss in neutralization capacity against primary isolates by these same V3-depleted sera was substantially less pronounced. This suggests that V3 peptide-specific antibodies within HIV-1 serum play a fundamentally different role in mediating neutralization in assays involving laboratory-adapted and primary isolates and implicates antibodies with epitope specificities outside of V3 as major determinants in neutralization assays involving primary isolates.

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Cell Line
  • DNA, Viral / genetics
  • Epitopes / immunology
  • HIV Antibodies / immunology*
  • HIV Envelope Protein gp120 / chemistry
  • HIV Envelope Protein gp120 / genetics
  • HIV Envelope Protein gp120 / immunology*
  • HIV Infections / immunology*
  • HIV Infections / virology
  • HIV-1 / immunology*
  • HIV-1 / isolation & purification
  • Humans
  • Molecular Sequence Data
  • Neutralization Tests
  • Peptide Fragments / chemistry
  • Peptide Fragments / genetics
  • Peptide Fragments / immunology*
  • Protein Conformation


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