Characterization of monoclonal antibodies to human immunodefiency virus type 1 gp41 by HIV-1 polypeptides expressed in Escherichia coli

Abstract Two monoclonal antibodies (MAbs) were produced in Balb/c mice by immunization with recombinant gp41 derived from expression of λ-BH10 cDNA of the human immunowdeficiency virus-1 (HIV-1) in the prokaryotic expression vector pEX-41 1, 2]. Characterization of the epitopes recognized by these MAbs was done with HIV-1 envelope (env) fusion proteins expressed in Escherochia coli encoding ten distinct segments of the env proteins 3]. In comparison, another mouse MAb, M25 4], a human MAb directed against gp41, which was produced by the xeno hydridoma line 3D6 5, 6] and a pool of human patient sera containing antibodies to HIV-1 were tested. We were able to demonstrate that the epitopes recognized by our MAbs are located betweeni arg732 and ser759 7] of the HIV-1 env glycoprotein gp160 of HTLV-III strain B. M25 reacted with epitopes between ser647 and pro731, which includes the hydrophobic transmembrane region of gp41 4]. The human MAb against gp41, 3D6 5, 6] reacts with epitopes between ile474 and trp646, a polypeptide stretch consisting of gp120 and gp41 specific amino acids. The human serum pool, positive for HIV-1 antibodies, reacted predominantly with antigenic determinants locatedp between ile474 and leu863. The recombinant env fusion proteins were initially produced to test the immunoreactivity with patient sera and to characterize epitopes which are relevant for immunodiagnostic purposes 3]. In this study, we showed that the set of recombinant evr proteins is also a simple and accurate tool for the characterization of MAbs directed to the HIV envelope proteins.