Characterization of Human Class-Switched Polymeric (Immunoglobulin M [IgM] and IgA) Anti-Human Immunodeficiency Virus Type 1 Antibodies 2F5 and 2G12

Abstract

We have previously generated human monoclonal anti-human immunodeficiency virus type 1 (anti-HIV-1) antibodies 2F5IgG and 2G12IgG with an exceptional cross-clade neutralizing potential. 2F5IgG and 2G12IgG passively administrated to macaques were able to confer complete protection from both intravenous and mucosal challenge with pathogenic HIV-simian immunodeficiency virus chimeric strains and have shown beneficial effects in a phase-1 clinical trial. We now class-switched 2F5 and 2G12 to the immunoglobulin M (IgM) or IgA isotype, to enforce features like avidity, complement activation, or the potential to neutralize mucosal transmission. For this purpose we expressed functional polymeric 2F5 and 2G12 antibodies in CHO cells and evaluated their anti-HIV-1 activity in vitro. The class switch had a strong impact on the protective potential of 2F5 and 2G12. 2G12IgM inhibited HIV-1 infection of peripheral blood mononuclear cell cultures up to 28-fold-more efficiently than the corresponding IgG and neutralized all of the primary isolates tested. The 2F5 and 2G12 antibodies of all isotypes were able to interact with active human serum to inhibit viral infection. Furthermore, we demonstrated that polymeric 2F5 and 2G12 antibodies but not the corresponding IgGs could interfere with HIV-1 entry across a mucosal epithelial layer in vitro. Although polymeric 2F5 antibodies had only limited potential in the standard neutralization assay, the results from the mucosal assay suggest that 2F5 and 2G12 antibodies may have a high potential to prevent natural HIV-1 transmission in vivo.

Enhanced HIV-1 neutralization by antibody heteroligation

“…For example, polymeric 2F5 and 2G12 antibodies (IgA and IgM) showed greater neutralizing breadth and potency than their monomeric IgG counterparts (66). In addition, a dimeric form of 2G12 IgG bNAb also increased its neutralization potency (67).…”

Cost-effective production of a vaginal protein microbicide to prevent HIV transmission

“…The 50% inhibiting concentration (IC 50 ) of maize-derived 2G12 was 2.88 g/ml, whereas that of the control (CHO) antibody was 8.11 g/ml, demonstrating that the maize 2G12 preparation was nearly three times as potent as its CHO counterpart. This apparent increase in neutralization efficiency probably reflects the presence of dimers and other aggregates in the maize preparation, which are known to have higher neutralization ability than monomeric antibody forms (33).…”

Evaluating the bottlenecks of recombinant IgM production in mammalian cells

“…IgM-012 takes its variable region sequence from the 2G12 IgG, famous, broadly neutralizing anti-HIV1 antibody (Kunert et al 1998). Variable regions of above mentioned antibodies-which are defining the specificity-were cloned into the bicistronic vectors containing either heavy or light chain constant regions of human IgM, as described previously by Wolbank et al (2003), providing the class-switch in the case of IgM-012.…”

“…Briefly, the variable HCs were inserted into a pIRES vector consisting of a SV40 promoter (Wolbank et al 2003), a human l-constant region backbone including leader sequence and the dihydrofolate reductase (DHFR) gene located after the IRES sequence. The LCs were inserted into a pIRES vector consisting of a CMV promoter, a human j-constant backbone including leader sequence, the human JC located after the IRES sequence and a neomycin resistance cassette under the control of a SV40 promoter.…”