title: Cross-reactive human immunodeficiency virus type 1-neutralizing human monoclonal antibody that recognizes a novel conformational epitope on gp41 and lacks reactivity against self-antigens.
abstract: Broadly cross-reactive human immunodeficiency virus (HIV)-neutralizing antibodies are infrequently elicited in infected humans. The two best-characterized gp41-specific cross-reactive neutralizing human monoclonal antibodies, 4E10 and 2F5, target linear epitopes in the membrane-proximal external region (MPER) and bind to cardiolipin and several other autoantigens. It has been hypothesized that, because of such reactivity to self-antigens, elicitation of 2F5 and 4E10 and similar antibodies by vaccine immunogens based on the MPER could be affected by tolerance mechanisms. Here, we report the identification and characterization of a novel anti-gp41 monoclonal antibody, designated m44, which neutralized most of the 22 HIV type 1 (HIV-1) primary isolates from different clades tested in assays based on infection of peripheral blood mononuclear cells by replication-competent virus but did not bind to cardiolipin and phosphatidylserine in an enzyme-linked immunosorbent assay and a Biacore assay nor to any protein or DNA autoantigens tested in Luminex assays. m44 bound to membrane-associated HIV-1 envelope glycoproteins (Envs), to recombinant Envs lacking the transmembrane domain and cytoplasmic tail (gp140s), and to gp41 structures containing five-helix bundles and six-helix bundles, but not to N-heptad repeat trimers, suggesting that the C-heptad repeat is involved in m44 binding. In contrast to 2F5, 4E10, and Z13, m44 did not bind to any significant degree to denatured gp140 and linear peptides derived from gp41, suggesting a conformational nature of the epitope. This is the first report of a gp41-specific cross-reactive HIV-1-neutralizing human antibody that does not have detectable reactivity to autoantigens. Its novel conserved conformational epitope on gp41 could be helpful in the design of vaccine immunogens and as a target for therapeutics.
authors.affiliation: CCRNP, CCR, NCI-Frederick, NIH, Bldg. 469, Rm. 131, P.O. Box B, Miller Drive, Frederick, MD 21702-1201, USA. zhangm@ncifcrf.gov
authors.forename: Mei-Yun
authors.initials: MY
authors.lastname: Zhang
authors.forename: Bang K
authors.initials: BK
authors.lastname: Vu
authors.forename: Anil
authors.initials: A
authors.lastname: Choudhary
authors.forename: Hong
authors.initials: H
authors.lastname: Lu
authors.forename: Michael
authors.initials: M
authors.lastname: Humbert
authors.forename: Helena
authors.initials: H
authors.lastname: Ong
authors.forename: Munir
authors.initials: M
authors.lastname: Alam
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Ruprecht
authors.forename: Gerald
authors.initials: G
authors.lastname: Quinnan
authors.forename: Shibo
authors.initials: S
authors.lastname: Jiang
authors.forename: David C
authors.initials: DC
authors.lastname: Montefiori
authors.forename: John R
authors.initials: JR
authors.lastname: Mascola
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Broder
authors.forename: Barton F
authors.initials: BF
authors.lastname: Haynes
authors.forename: Dimiter S
authors.initials: DS
authors.lastname: Dimitrov
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology*; D000914:Antibodies, Viral / Q000276:immunology*; D001324:Autoantigens / Q000276:immunology*; D002308:Cardiolipins / Q000276:immunology / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D003429:Cross Reactions; D004247:DNA / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology*; D015700:HIV Envelope Protein gp41 / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000821:virology; D009500:Neutralization Tests; D010718:Phosphatidylserines / Q000276:immunology / Q000378:metabolism; D011485:Protein Binding; D020349:Surface Plasmon Resonance
chemical_list: D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D001324:Autoantigens; D002308:Cardiolipins; D000939:Epitopes; D015700:HIV Envelope Protein gp41; D010718:Phosphatidylserines; C514787:gp41 protein, Human immunodeficiency virus 1; D004247:DNA