Characterization of a Novel Human Anti-HIV-1 gp41 IgM Monoclonal Antibody Designated Clone 37

Abstract

Human monoclonal antibodies (HuMAbs) demonstrate great potential for passive immunotherapy against HIV-1. The gp41 transmembrane envelope glycoprotein of HIV has an important role in the pathogenicity of AIDS and importantly displays considerably less hypervariability than the gp120 surface envelope HIV glycoprotein, which makes it particularly a better candidate for the development of passive and active immunotherapies. The general aim of this study was to develop HuMAbs to HIV surface glycoproteins and particularly gp41. Peripheral blood mononuclear cells (PBMCs) were isolated from an HIV-seropositive long-term nondisease progressing patient. B-cells from this individual were then immortalized by Epstein-Barr virus (EBV) transformation, and antibody production was stabilized by fusion of transformed cells with a heteromyeloma. Subsets of the human heterohybridomas so generated were analyzed by ELISA. The hybridoma with the highest binding by immunoassay against gp160 was further analyzed. This hybridoma, designated as clone 37 (C37), was determined to be an IgM Kappa antibody and overlapping peptides of HIV envelope proteins (derived from the MN tissue culture line adapted HIV isolate) were used to map the specific binding domain of this HuMAb. Overlapping peptides designated 2026 (SWSNKSLDDIWNN, AA614-626), and 2027 (DDIWNNMTWMQWEREIDNYT, AA621-640) within the HIV-1 gp41 transmembrane glycoprotein were demonstrated to bind to C37 indicating that the specific binding domain for the antibody was DDIWNN. High affinity binding of C37 by ELISA to recombinant gp41 was demonstrated as well. Few IgM HuMAbs against HIV have been generated and characterized. Theoretically, because of the pentameric binding nature of IgM antibodies as well as their very efficient ability to activate complement, such reagents could have potential as anti-HIV agents.

A Pharmacologically Active Monoclonal Antibody against the Human Melanocortin-4 Receptor: Effectiveness After Peripheral and Central Administration

“…These results are consistent with our immunoprecipitation experiments that indicated that mAb 1E8a bound to hMC4R and rMC4R with high affinity, whereas the mAb 2G2 interacted only with the NT peptide The affinity of the mAb 1E8a and the mAb 2G2 for the NT peptide were in the same range (1.3 ϫ 10 Ϫ8 and 3.7 ϫ 10 Ϫ8 M, respectively). They are relatively high for an IgM isotype, but other high-affinity IgM mAbs have been described previously (Ballard et al, 1983;Suenaga and Abdou, 1992;Cao et al, 2004). The small difference between the affinity of mAbs 1E8a and 2G2 cannot explain why the latter did not interact with the MC4R.…”

HIV-1 neutralizing antibodies elicited by the candidate CBD1 epitope vaccine react with the conserved caveolin-1 binding motif of viral glycoprotein gp41

“…Nevertheless, we cannot rule out the possibility of the existence of a small proportion of anti-CBD1 antibodies that react with specific linear epitopes. Recently, a human IgM mAb C37 binding to the sequence IWNNM in the caveolin-binding motif was isolated from an HIV-seropositive long-term non-disease progressing patient (Cao et al 2004). Whether or not mAb C37 has the capacity to neutralize HIV-1 infection has not yet been reported.…”

Identifiable biomarker and treatment development using HIV-1 long term non-progressor sera

“…al. (2004) [ 35 ], and we found that CL3 binds to peptide 2025. This antibody can successfully neutralize HIV-1 clade B clinical isolate (Figure 4 ).…”