A single amino-acid change in a highly conserved motif of gp41 elicits HIV-1 neutralization and protects against CD4 depletion

Clin Infect Dis. 2013 Sep;57(5):745-55. doi: 10.1093/cid/cit335. Epub 2013 May 21.


Background: The induction of neutralizing antibodies against conserved regions of the human immunodeficiency virus type 1 (HIV-1) envelope protein is a major goal of vaccine strategies. We previously identified 3S, a critical conserved motif of gp41 that induces the NKp44L ligand of an activating NK receptor. In vivo, anti-3S antibodies protect against the natural killer (NK) cell-mediated CD4 depletion that occurs without efficient viral neutralization.

Methods: Specific substitutions within the 3S peptide motif were prepared by directed mutagenesis. Virus production was monitored by measuring the p24 production. Neutralization assays were performed with immune-purified antibodies from immunized mice and a cohort of HIV-infected patients. Expression of NKp44L on CD4(+) T cells and degranulation assay on activating NK cells were both performed by flow cytometry.

Results: Here, we show that specific substitutions in the 3S motif reduce viral infection without affecting gp41 production, while decreasing both its capacity to induce NKp44L expression on CD4(+) T cells and its sensitivity to autologous NK cells. Generation of antibodies in mice against the W614 specific position in the 3S motif elicited a capacity to neutralize cross-clade viruses, notable in its magnitude, breadth, and durability. Antibodies against this 3S variant were also detected in sera from some HIV-1-infected patients, demonstrating both neutralization activity and protection against CD4 depletion.

Conclusions: These findings suggest that a specific substitution in a 3S-based immunogen might allow the generation of specific antibodies, providing a foundation for a rational vaccine that combine a capacity to neutralize HIV-1 and to protect CD4(+) T cells.

Keywords: CD4 depletion; HIV-1; NK cytotoxicity; NKp44L; neutralizing activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Amino Acid Substitution
  • Animals
  • Antibodies, Neutralizing / blood
  • CD4 Lymphocyte Count
  • CD4-Positive T-Lymphocytes / immunology*
  • Female
  • HIV Antibodies / blood*
  • HIV Envelope Protein gp41 / genetics*
  • HIV Envelope Protein gp41 / immunology*
  • HIV-1 / genetics*
  • HIV-1 / immunology*
  • Humans
  • Killer Cells, Natural / immunology
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Middle Aged
  • Mutant Proteins / genetics
  • Mutant Proteins / immunology
  • Mutation, Missense
  • Young Adult


  • Antibodies, Neutralizing
  • HIV Antibodies
  • HIV Envelope Protein gp41
  • Mutant Proteins
  • gp41 protein, Human immunodeficiency virus 1