A HUMAN MONOCLONAL-ANTIBODY TO HIV-1 GP41 WITH NEUTRALIZING ACTIVITY AGAINST DIVERSE LABORATORY ISOLATES

A potential component that may be useful for passive immunotherapy for HIV-1 is human monoclonal antibodies (HumAbs) possessing potent anti- HIV-1 activity that is directed against conserved regions of the envel ope glycoprotein. Such antibodies would, in principle, have the abilit y to neutralize diverse isolates of HIV-1. To develop such reagents, h ybridomas were derived by initial Epstein Barr virus transformation of peripheral blood mononuclear cells (PBMCs) from an asymptomatic HIV-1 seropositive donor followed by fusion with heteromyelomas, and secret ed anti-HIV-1 antibodies were further characterized. The specificity o f one HumAb, designated as clone 3, was determined by enzyme-linked im munosorbent assay (ELISA) and Western blotting analyses that indicated reactivity to the transmembrane envelope glycoprotein gp41. Synthetic pentadecapeptides overlapping by 10 amino acids were utilized for epi tope mapping of clone 3; a decapeptide GCSGKLICTT in the transmembrane gp41 was identified as the epitope. Clone 3 bound to SupT1 cells infe cted with HTLV-IIIB in fluorescent activated cell sorting analysis. In addition, in vitro biological assays demonstrated that clone 3 posses sed neutralization reactivity against diverse laboratory isolates as w ell as an AZT-resistant isolate. Therefore, clone 3 reactivity defines a conserved neutralizable site on the HIV-1 transmembrane glycoprotei n. Clone 3 and the conserved immunogenic epitope on gp41 could be usef ul in passive and active immunotherapy for the acquired immunodeficien cy syndrome (AIDS).