title: Fine definition of the epitope on the gp41 glycoprotein of human immunodeficiency virus type 1 for the neutralizing monoclonal antibody 2F5.
abstract: Matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS), in combination with proteolytic protection assays, has been used to identify the functional epitope on human immunodeficiency virus envelope glycoprotein gp41 for the broadly neutralizing anti-gp41 human monoclonal antibody 2F5. In this protection assay-based procedure, a soluble gp140 protein with a stabilizing intermolecular disulfide bond between the gp120 and gp41 subunits (SOS gp140) was affinity bound to immobilized 2F5 under physiological conditions. A combination of proteolytic enzymatic cleavages was then performed to remove unprotected residues. Residues of SOS gp140 protected by their binding to 2F5 were then identified based on their molecular weights as determined by direct MALDI-MS of the immobilized antibody beads. The epitope, NEQELLELDKWASLWN, determined by this MALDI-MS protection assay approach consists of 16 amino acid residues near the C terminus of gp41. It is significantly longer than the ELDKWA core epitope previously determined for 2F5 by peptide enzyme-linked immunosorbent assay. This new knowledge of the structure of the 2F5 epitope may facilitate the design of vaccine antigens intended to induce antibodies with the breadth and potency of action of the 2F5 monoclonal antibody.
authors.affiliation: Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA. Carol_Parker@med.unc.edu
authors.forename: C E
authors.initials: CE
authors.lastname: Parker
authors.forename: L J
authors.initials: LJ
authors.lastname: Deterding
authors.forename: C
authors.initials: C
authors.lastname: Hager-Braun
authors.forename: J M
authors.initials: JM
authors.lastname: Binley
authors.forename: N
authors.initials: N
authors.lastname: Schülke
authors.forename: H
authors.initials: H
authors.lastname: Katinger
authors.forename: J P
authors.initials: JP
authors.lastname: Moore
authors.forename: K B
authors.initials: KB
authors.lastname: Tomer
mesh_terms: D016915:AIDS Vaccines / Q000276:immunology; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D016466:CHO Cells; D006224:Cricetinae; D018604:Epitope Mapping; D015483:HIV Antibodies / Q000276:immunology*; D015700:HIV Envelope Protein gp41 / Q000737:chemistry / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D009500:Neutralization Tests
chemical_list: D016915:AIDS Vaccines; D000911:Antibodies, Monoclonal; D015483:HIV Antibodies; D015700:HIV Envelope Protein gp41