Abstract
The membrane proximal external region (MPER) of the HIV-1 glycoprotein gp41 is targeted by the broadly neutralizing antibodies 2F5 and 4E10. To date, no immunization regimen in animals or humans has produced HIV-1 neutralizing MPER-specific antibodies. We immunized llamas with gp41-MPER proteoliposomes and selected a MPER-specific single chain antibody (VHH), 2H10, whose epitope overlaps with that of mAb 2F5. Bi-2H10, a bivalent form of 2H10, which displayed an approximately 20-fold increased affinity compared to the monovalent 2H10, neutralized various sensitive and resistant HIV-1 strains, as well as SHIV strains in TZM-bl cells. X-ray and NMR analyses combined with mutagenesis and modeling revealed that 2H10 recognizes its gp41 epitope in a helical conformation. Notably, tryptophan 100 at the tip of the long CDR3 is not required for gp41 interaction but essential for neutralization. Thus bi-2H10 is an anti-MPER antibody generated by immunization that requires hydrophobic CDR3 determinants in addition to epitope recognition for neutralization similar to the mode of neutralization employed by mAbs 2F5 and 4E10.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Antibodies, Neutralizing / immunology*
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Base Sequence
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Camelids, New World / immunology*
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Cell Line
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Complementarity Determining Regions / immunology*
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Epitopes / immunology
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HIV Antibodies / immunology*
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HIV Envelope Protein gp41 / immunology*
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Humans
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Hydrophobic and Hydrophilic Interactions
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Immunization
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Molecular Sequence Data
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Mutagenesis, Site-Directed
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Neutralization Tests
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Proteolipids / administration & dosage
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Proteolipids / immunology
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Single-Domain Antibodies
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Surface Plasmon Resonance
Substances
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Antibodies, Neutralizing
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Complementarity Determining Regions
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Epitopes
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HIV Antibodies
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HIV Envelope Protein gp41
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Proteolipids
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Single-Domain Antibodies
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proteoliposomes
Grants and funding
This work was supported by the Bill & Melinda Gates Foundation as part of the Collaboration for AIDS Vaccine Discovery (CAVD grant 38637), Combined Highly Active Anti- Retroviral Microbicides (CHAARM:
http://chaarm.eu/), the Dutch Foundation for Scientific Research (NWO) through a VICI grant (no. 700.56.442) (AMJJB), the TGE RMN THC Fr3050 (JPS) and the LabEX GRAL (WW). MH is supported by a post-doctoral fellowship from Sidaction and WW is supported by the Institut Universitaire de France. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.