title: The HIV-neutralizing monoclonal antibody 4E10 recognizes N-terminal sequences on the native antigen.
abstract: Characterization of the epitope recognized by the broadly neutralizing anti-HIV Ab 4E10 has, heretofore, focused on a linear sequence from the gp41 pretransmembrane region (PTMR). Attempts to generate neutralizing Abs based on this linear epitope sequence have been unsuccessful. We have characterized the antigenic determinants on recombinant glycosylated full-length Ags, and nonglycosylated and truncated Ags recognized by 4E10 using epitope extraction and excision assays in conjunction with MALDI mass spectrometry. The mAb recognized the peptides (34)LWVTVYYGVPVWK(46) and (512)AVGIGAVFLGFLGAAGSTMGAASMTLTVQAR(542) located at the N-terminal region of gp120 and gp41, respectively. Immunoassays verified AV(L/M)FLGFLGAA as the gp41 epitope core. Recognition of the peptide from the gp41 PTMR was detected only in constructs in which the N termini of the mature envelope proteins were missing. In this region, the epitope core is located in the sequence (672)WFDITNWLWY(681). We hypothesize that the hydrophobic surface of the paratope functions as a "trap" for the viral sequences, which are responsible for insertion into the host cell membrane. As the N-terminal region of gp120, the fusogenic peptide of gp41, and the PTMR of gp41 show high sequence homology among various HIV strains, this model is consistent with the broadly neutralizing capabilities of 4E10.
authors.affiliation: National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, USA. christine_hager-braun@ncsu.edu
authors.forename: Christine
authors.initials: C
authors.lastname: Hager-Braun
authors.forename: Hermann
authors.initials: H
authors.lastname: Katinger
authors.forename: Kenneth B
authors.initials: KB
authors.lastname: Tomer
mesh_terms: D000595:Amino Acid Sequence; D019380:Anti-HIV Agents / Q000378:metabolism*; D000911:Antibodies, Monoclonal / Q000378:metabolism*; D000914:Antibodies, Viral / Q000378:metabolism*; D000918:Antibody Specificity; D001666:Binding Sites, Antibody; D004797:Enzyme-Linked Immunosorbent Assay; D018604:Epitope Mapping; D000939:Epitopes / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D006678:HIV / Q000276:immunology* / Q000472:pathogenicity; D015699:HIV Envelope Protein gp120 / Q000276:immunology / Q000378:metabolism; D015700:HIV Envelope Protein gp41 / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D008561:Membrane Fusion / Q000276:immunology; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000276:immunology / Q000378:metabolism*; D011487:Protein Conformation; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D019380:Anti-HIV Agents; D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D000939:Epitopes; D015699:HIV Envelope Protein gp120; D015700:HIV Envelope Protein gp41; D010446:Peptide Fragments