title: Dissecting the carbohydrate specificity of the anti-HIV-1 2G12 antibody by single-molecule force spectroscopy.
abstract: Broadly neutralizing anti-HIV-1 monoclonal antibody 2G12 exclusively targets a conserved cluster of high-mannose oligosaccharides present on outer viral envelope glycoprotein gp120. This characteristic makes the otherwise immunogenically "silent" glycan shield of gp120 a tempting target for drug and vaccine design. However, immune responses against carbohydrate-based mimics of gp120 have failed to provide immunization against HIV-1 infection, highlighting the need to understand the molecular events that determine immunogenicity better. In this work, the unbinding kinetics of the gp120-2G12 (k(0) = 0.002 ± 0.09 s(-1), x(++) = 1.5 ± 1.2 nm), Man(4)-2G12 (k(0) = 0.35 ± 0.32 s(-1), x(++) = 0.6 ± 0.2 nm), and Man(5)-2G12 interactions were measured by single-molecule force spectroscopy. To our knowledge, this is the first single-molecule study aimed at dissecting the carbohydrate-antibody recognition of the gp120-2G12 interaction. We were able to confirm crystallographic models that show both the binding of the linear Man(4) arm to 2G12 and also the multivalent gp120 glycan binding to 2G12. These results demonstrate that single-molecule force spectroscopy can be successfully used to dissect the molecular mechanisms underlying immunity.
authors.affiliation: Laboratory of Glyconanotechnology, Biofunctional Nanomaterials Unit, Paseo de Miramón 182, 20009 San Sebastian, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Martines
authors.forename: Isabel
authors.initials: I
authors.lastname: García
authors.forename: Marco
authors.initials: M
authors.lastname: Marradi
authors.forename: Daniel
authors.initials: D
authors.lastname: Padro
authors.forename: Soledad
authors.initials: S
authors.lastname: Penadés
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology*; D000918:Antibody Specificity; D000080908:Broadly Neutralizing Antibodies; D015483:HIV Antibodies; D015699:HIV Envelope Protein gp120 / Q000737:chemistry* / Q000276:immunology*; D015497:HIV-1; D007700:Kinetics; D008358:Mannose / Q000276:immunology*; D018625:Microscopy, Atomic Force
chemical_list: C529157:2G12 monoclonal antibody; D000911:Antibodies, Monoclonal; D000080908:Broadly Neutralizing Antibodies; D015483:HIV Antibodies; D015699:HIV Envelope Protein gp120; C514793:gp120 protein, Human immunodeficiency virus 1; D008358:Mannose