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GPI-anchored single chain Fv--an effective way to capture transiently-exposed neutralization epitopes on HIV-1 envelope spike.

ABSTRACT: BACKGROUND:Identification of broad neutralization epitopes in HIV-1 envelope spikes is paramount for HIV-1 vaccine development. A few broad neutralization epitopes identified so far are present on the surface of native HIV-1 envelope spikes whose recognition by antibodies does not depend on conformational changes of the envelope spikes. However, HIV-1 envelope spikes also contain transiently-exposed neutralization epitopes, which are more difficult to identify. RESULTS:In this study, we constructed single chain Fvs (scFvs) derived from seven human monoclonal antibodies and genetically linked them with or without a glycosyl-phosphatidylinositol (GPI) attachment signal. We show that with a GPI attachment signal the scFvs are targeted to lipid rafts of plasma membranes. In addition, we demonstrate that four of the GPI-anchored scFvs, but not their secreted counterparts, neutralize HIV-1 with various degrees of breadth and potency. Among them, GPI-anchored scFv (X5) exhibits extremely potent and broad neutralization activity against multiple clades of HIV-1 strains tested. Moreover, we show that GPI-anchored scFv (4E10) also exhibited more potent neutralization activity than its secretory counterpart. Finally, we demonstrate that expression of GPI-anchored scFv (X5) in the lipid raft of plasma membrane of human CD4+ T cells confers long-term resistance to HIV-1 infection, HIV-1 envelope-mediated cell-cell fusion, and the infection of HIV-1 captured and transferred by human DCs. CONCLUSIONS:Thus GPI-anchored scFv could be used as a general and effective way to identify antibodies that react with transiently-exposed neutralization epitopes in envelope proteins of HIV-1 and other enveloped viruses. The GPI-anchored scFv (X5), because of its breadth and potency, should have a great potential to be developed into anti-viral agent for HIV-1 prevention and therapy.

SUBMITTER: Wen M

PROVIDER: S-EPMC2959034 | biostudies-literature | 2010 Oct

REPOSITORIES: biostudies-literature

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GPI-anchored single chain Fv--an effective way to capture transiently-exposed neutralization epitopes on HIV-1 envelope spike.

Wen Michael M Arora Reetakshi R Wang Huiqiang H Liu Lihong L Kimata Jason T JT Zhou Paul P

Retrovirology 20101006

<h4>Background</h4>Identification of broad neutralization epitopes in HIV-1 envelope spikes is paramount for HIV-1 vaccine development. A few broad neutralization epitopes identified so far are present on the surface of native HIV-1 envelope spikes whose recognition by antibodies does not depend on conformational changes of the envelope spikes. However, HIV-1 envelope spikes also contain transiently-exposed neutralization epitopes, which are more difficult to identify.<h4>Results</h4>In this stu ...[more]

PMID: 20923574

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Project description:UNLABELLED:The potency and breadth of the recently isolated neutralizing human monoclonal antibodies to HIV-1 have stimulated interest in their use to prevent or to treat HIV-1 infection. Due to the antigenically diverse nature of the HIV-1 envelope (Env), no single antibody is highly active against all viral strains. While the physical combination of two broadly neutralizing antibodies (bNAbs) can improve coverage against the majority of viruses, the clinical-grade manufacturing and testing of two independent antibody products are time and resource intensive. In this study, we constructed bispecific immunoglobulins (IgGs) composed of independent antigen-binding fragments with a common Fc region. We developed four different bispecific IgG variants that included antibodies targeting four major sites of HIV-1 neutralization. We show that these bispecific IgGs display features of both antibody specificities and, in some cases, display improved coverage over the individual parental antibodies. All four bispecific IgGs neutralized 94% to 97% of antigenically diverse viruses in a panel of 206 HIV-1 strains. Among the bispecific IgGs tested, VRC07 × PG9-16 displayed the most favorable neutralization profile. It was superior in breadth to either of the individual antibodies, neutralizing 97% of viruses with a median 50% inhibitory concentration (IC50) of 0.055 ?g/ml. This bispecific IgG also demonstrated in vivo pharmacokinetic parameters comparable to those of the parental bNAbs when administered to rhesus macaques. These results suggest that IgG-based bispecific antibodies are promising candidates for the prevention and treatment of HIV-1 infection in humans. IMPORTANCE:To prevent or treat HIV-1 infection, antibodies must potently neutralize nearly all strains of HIV-1. Thus, the physical combination of two or more antibodies may be needed to broaden neutralization coverage and diminish the possibility of viral resistance. A bispecific antibody that has two different antibody binding arms could potentially display neutralization characteristics better than those of any single parental antibody. Here we show that bispecific antibodies contain the binding specificities of the two parental antibodies and that a single bispecific antibody can neutralize 97% of viral strains with a high overall potency. These findings support the use of bispecific antibodies for the prevention or treatment of HIV-1 infection.

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GPI-anchored single chain Fv--an effective way to capture transiently-exposed neutralization epitopes on HIV-1 envelope spike.

Publications

GPI-anchored single chain Fv--an effective way to capture transiently-exposed neutralization epitopes on HIV-1 envelope spike.

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