title: ELDKWA-epitope-specific monoclonal antibodies inhibit HIV env-mediated syncytium formation.
abstract: Recent studies demonstrated that the N- and C-domains of HIV-1 gp41 are involved in virus-mediated membrane fusion resulting in HIV-entry into target cells. Synthetic N- and C-domain peptides, such as DP107 and DP178, potently inhibit membrane fusion induced by both laboratory-adapted strains and primary isolates of HIV-1. Monoclonal antibody (mAb) 2F5 recognizing ELDKWA-epitope on the gp41 C-domain has shown broad neutralizing activity to many HIV stains even primary isolates. To test the neutralizing mechanism of the ELDKWA-epitope-specific antibody, mAbs with predefined ELDKWA-epitope-specificity were induced by synthetic epitope-peptide instead of a natural or recombinant gp41 bearing this epitope. All of five mAbs were identified to recognize ELDKWA-epitope on recombinant soluble gp41 in ELISA-assay. In flow cytometry analysis, four out of five mAbs could bind to HIV-Env+ CHO-WT cells and such binding could be inhibited by ELDKWA-epitope peptide, which suggests that these mAbs could recognize native envelope protein expressed on cell membranes. Interestingly, two out of five mAbs could inhibit membrane fusion between the CXCR4- and CD4-expressing 3T3.T4.CXCR4 cells and HIV-Env+ CHO-WT cells in a dose-dependent manner, consistent with their potent binding capability to HIV-Env+ CHO-WT cells. Parren et al. (1998) suggested that neutralization of HIV-1 by antibody may be determined primarily by occupancy of sites and spatial obstruction which blocks virus entry. Based on this theory, a model was suggested to explain the neutralizing activities of mAbs against the epitope ELDKWA.
authors.affiliation: Laboratory of Immunology, Research Centre for Medical Science and Department of Biology, Tsinghua University, Beijing 100084, P.R. China.
authors.forename: Geng
authors.initials: G
authors.lastname: Zhang
authors.forename: Ying-Hua
authors.initials: YH
authors.lastname: Chen
mesh_terms: D016475:3T3 Cells; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000918:Antibody Specificity; D016466:CHO Cells; D002459:Cell Fusion; D006224:Cricetinae; D000939:Epitopes / Q000737:chemistry / Q000276:immunology*; D015726:Giant Cells / Q000276:immunology*; D015483:HIV Antibodies / Q000096:biosynthesis; D015700:HIV Envelope Protein gp41 / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D009500:Neutralization Tests; D017434:Protein Structure, Tertiary; D014407:Tumor Cells, Cultured
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D015483:HIV Antibodies; D015700:HIV Envelope Protein gp41