title: A single amino-acid change in a highly conserved motif of gp41 elicits HIV-1 neutralization and protects against CD4 depletion.
abstract: 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.
authors.affiliation: Immunité et Infection, Hôpital Pitié-Salpêtrière, INSERM UMR-S 945, Paris, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Petitdemange
authors.forename: Abla
authors.initials: A
authors.lastname: Achour
authors.forename: Stefania
authors.initials: S
authors.lastname: Dispinseri
authors.forename: Isabelle
authors.initials: I
authors.lastname: Malet
authors.forename: Alexis
authors.initials: A
authors.lastname: Sennepin
authors.forename: Raphaël
authors.initials: R
authors.lastname: Ho Tsong Fang
authors.forename: Joël
authors.initials: J
authors.lastname: Crouzet
authors.forename: Anne-Geneviève
authors.initials: AG
authors.lastname: Marcelin
authors.forename: Vincent
authors.initials: V
authors.lastname: Calvez
authors.forename: Gabriella
authors.initials: G
authors.lastname: Scarlatti
authors.forename: Patrice
authors.initials: P
authors.lastname: Debré
authors.forename: Vincent
authors.initials: V
authors.lastname: Vieillard
mesh_terms: D000293:Adolescent; D000328:Adult; D019943:Amino Acid Substitution; D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D005260:Female; D015483:HIV Antibodies / Q000097:blood*; D015700:HIV Envelope Protein gp41 / Q000235:genetics* / Q000276:immunology*; D015497:HIV-1 / Q000235:genetics* / Q000276:immunology*; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008875:Middle Aged; D050505:Mutant Proteins / Q000235:genetics / Q000276:immunology; D020125:Mutation, Missense; D055815:Young Adult
chemical_list: D057134:Antibodies, Neutralizing; D015483:HIV Antibodies; D015700:HIV Envelope Protein gp41; D050505:Mutant Proteins; C514787:gp41 protein, Human immunodeficiency virus 1
keywords: CD4 depletion; HIV-1; NK cytotoxicity; NKp44L; neutralizing activity