title: Analysis of memory B cell responses and isolation of novel monoclonal antibodies with neutralizing breadth from HIV-1-infected individuals.
abstract: BACKGROUND
  The isolation of human monoclonal antibodies (mAbs) that neutralize a broad spectrum of primary HIV-1 isolates and the characterization of the human neutralizing antibody B cell response to HIV-1 infection are important goals that are central to the design of an effective antibody-based vaccine.
  
  
  RESULTS
  We immortalized IgG(+) memory B cells from individuals infected with diverse clades of HIV-1 and selected on the basis of plasma neutralization profiles that were cross-clade and relatively potent. Culture supernatants were screened using various recombinant forms of the envelope glycoproteins (Env) in multiple parallel assays. We isolated 58 mAbs that were mapped to different Env surfaces, most of which showed neutralizing activity. One mAb in particular (HJ16) specific for a novel epitope proximal to the CD4 binding site on gp120 selectively neutralized a multi-clade panel of Tier-2 HIV-1 pseudoviruses, and demonstrated reactivity that was comparable in breadth, but distinct in neutralization specificity, to that of the other CD4 binding site-specific neutralizing mAb b12. A second mAb (HGN194) bound a conserved epitope in the V3 crown and neutralized all Tier-1 and a proportion of Tier-2 pseudoviruses tested, irrespective of clade. A third mAb (HK20) with broad neutralizing activity, particularly as a Fab fragment, recognized a highly conserved epitope in the HR-1 region of gp41, but showed striking assay-dependent selectivity in its activity.
  
  
  CONCLUSIONS
  This study reveals that by using appropriate screening methods, a large proportion of memory B cells can be isolated that produce mAbs with HIV-1 neutralizing activity. Three of these mAbs show unusual breadth of neutralization and therefore add to the current panel of HIV-1 neutralizing antibodies with potential for passive protection and template-based vaccine design.
authors.affiliation: Institute for Research in Biomedicine, Bellinzona, Switzerland.
authors.forename: Davide
authors.initials: D
authors.lastname: Corti
authors.forename: Johannes P M
authors.initials: JP
authors.lastname: Langedijk
authors.forename: Andreas
authors.initials: A
authors.lastname: Hinz
authors.forename: Michael S
authors.initials: MS
authors.lastname: Seaman
authors.forename: Fabrizia
authors.initials: F
authors.lastname: Vanzetta
authors.forename: Blanca M
authors.initials: BM
authors.lastname: Fernandez-Rodriguez
authors.forename: Chiara
authors.initials: C
authors.lastname: Silacci
authors.forename: Debora
authors.initials: D
authors.lastname: Pinna
authors.forename: David
authors.initials: D
authors.lastname: Jarrossay
authors.forename: Sunita
authors.initials: S
authors.lastname: Balla-Jhagjhoorsingh
authors.forename: Betty
authors.initials: B
authors.lastname: Willems
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Zekveld
authors.forename: Hanna
authors.initials: H
authors.lastname: Dreja
authors.forename: Eithne
authors.initials: E
authors.lastname: O'Sullivan
authors.forename: Corinna
authors.initials: C
authors.lastname: Pade
authors.forename: Chloe
authors.initials: C
authors.lastname: Orkin
authors.forename: Simon A
authors.initials: SA
authors.lastname: Jeffs
authors.forename: David C
authors.initials: DC
authors.lastname: Montefiori
authors.forename: David
authors.initials: D
authors.lastname: Davis
authors.forename: Winfried
authors.initials: W
authors.lastname: Weissenhorn
authors.forename: Aine
authors.initials: A
authors.lastname: McKnight
authors.forename: Jonathan L
authors.initials: JL
authors.lastname: Heeney
authors.forename: Federica
authors.initials: F
authors.lastname: Sallusto
authors.forename: Quentin J
authors.initials: QJ
authors.lastname: Sattentau
authors.forename: Robin A
authors.initials: RA
authors.lastname: Weiss
authors.forename: Antonio
authors.initials: A
authors.lastname: Lanzavecchia
mesh_terms: D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000276:immunology*; D057134:Antibodies, Neutralizing / Q000737:chemistry / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D001666:Binding Sites, Antibody; D015704:CD4 Antigens / Q000276:immunology; D000939:Epitopes / Q000737:chemistry; D015658:HIV Infections / Q000276:immunology*; D015497:HIV-1; D006801:Humans; D007156:Immunologic Memory; D008969:Molecular Sequence Data
chemical_list: D000911:Antibodies, Monoclonal; D057134:Antibodies, Neutralizing; D015704:CD4 Antigens; D000939:Epitopes