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Kwong PD, Mascola JR. Human antibodies that neutralize HIV-1: identification, structures, and B cell ontogenies. Immunity 2012; 37:412-25. [PMID: 22999947 PMCID: PMC4706166 DOI: 10.1016/j.immuni.2012.08.012] [Citation(s) in RCA: 373] [Impact Index Per Article: 31.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 08/03/2012] [Accepted: 08/24/2012] [Indexed: 02/07/2023]
Abstract
Antibodies that neutralize diverse strains of HIV-1 develop in ∼20% of HIV-1-infected individuals, and isolation and structural characterization of these antibodies are revealing how they recognize the envelope glycoprotein spike. Broadly reactive neutralizing antibodies utilize just a few sites of spike vulnerability and converge on select modes of recognition. These antibodies have unusual features: uncommonly long complementarity-determining loops, extensive somatic mutation, or both. Recent advances in next-generation sequencing of antibody-gene transcripts are providing genetic records of the development of neutralizing antibodies. These records inform an understanding of the naive B cell repertoire, of somatic mutation, and of the resulting antibody features that are critical to effective HIV-1 neutralization; based on these, we propose an ontogeny and structure-based system of antibody classification. The human immune system is capable of developing antibodies that broadly neutralize HIV-1--and an increasingly detailed view is accumulating for how effective immunity against HIV-1 can be generated.
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Affiliation(s)
- Peter D. Kwong
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - John R. Mascola
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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Abstract
Antibody-based therapeutics have been successfully used for the treatment of various diseases and as research tools. Several well characterized, broadly neutralizing monoclonal antibodies (bnmAbs) targeting HIV-1 envelope glycoproteins or related host cell surface proteins show sterilizing protection of animals, but they are not effective when used for therapy of an established infection in humans. Recently, a number of novel bnmAbs, engineered antibody domains (eAds), and multifunctional fusion proteins have been reported which exhibit exceptionally potent and broad neutralizing activity against a wide range of HIV-1 isolates from diverse genetic subtypes. eAds could be more effective in vivo than conventional full-size antibodies generated by the human immune system. Because of their small size (12∼15 kD), they can better access sterically restricted epitopes and penetrate densely packed tissue where HIV-1 replicates than the larger full-size antibodies. HIV-1 possesses a number of mechanisms to escape neutralization by full-size antibodies but could be less likely to develop resistance to eAds. Here, we review the in vitro and in vivo antiviral efficacies of existing HIV-1 bnmAbs, summarize the development of eAds and multispecific fusion proteins as novel types of HIV-1 inhibitors, and discuss possible strategies to generate more potent antibody-based candidate therapeutics against HIV-1, including some that could be used to eradicate the virus.
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Affiliation(s)
- Rui Gong
- Protein Interactions Group, Frederick National Laboratory for Cancer Research, National Institutes of Health, Frederick, MD 21702-1201, USA.
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53
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Abstract
Although vaccines have proven life saving against a myriad of infectious diseases, various pathogens have remained refractory to prophylaxis of their host by active immunization. New insights in the three dimensional (3D) structure, domain organization and dynamics of viral and bacterial surface proteins can guide the design of effective vaccines in several ways. In this review we highlight recent developments in structure-based vaccine design that are aimed at stabilization of native conformations and focusing immune response to conserved epitopes. Detailed 3D structures of pathogen surface proteins provide knowledge on how to minimize complex antigens or how to redesign the surface of an immunogen in order to induce only relevant neutralizing antibodies against a broad range of serotypes. Structure - based vaccines with reduced complexity and broad efficacy could greatly enhance the number of people that might benefit from the therapies that are developed.
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Affiliation(s)
- Jaap W Back
- Pepscan Therapeutics, Lelystad, The Netherlands
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54
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Euler Z, Schuitemaker H. Cross-reactive broadly neutralizing antibodies: timing is everything. Front Immunol 2012; 3:215. [PMID: 22833745 PMCID: PMC3400945 DOI: 10.3389/fimmu.2012.00215] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 07/03/2012] [Indexed: 11/23/2022] Open
Abstract
The recent surge of research into new broadly neutralizing antibodies in HIV-1 infection has recharged the field of HIV-1 vaccinology. In this review we discuss the currently known broadly neutralizing antibodies and focus on factors that may shape these antibodies in natural infection. We further discuss the role of these antibodies in the clinical course of the infection and consider immunological obstacles in inducing broadly neutralizing antibodies with a vaccine.
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Affiliation(s)
- Zelda Euler
- Landsteiner Laboratory, Sanquin Research, Amsterdam, Netherlands
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55
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Human peripheral blood antibodies with long HCDR3s are established primarily at original recombination using a limited subset of germline genes. PLoS One 2012; 7:e36750. [PMID: 22590602 PMCID: PMC3348910 DOI: 10.1371/journal.pone.0036750] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 04/07/2012] [Indexed: 12/27/2022] Open
Abstract
A number of antibodies that efficiently neutralize microbial targets contain long heavy chain complementarity determining region 3 (HCDR3) loops. For HIV, several of the most broad and potently neutralizing antibodies have exceptionally long HCDR3s. Two broad potently neutralizing HIV-specific antibodies, PG9 and PG16, exhibit secondary structure. Two other long HCDR3 antibodies, 2F5 and 4E10, protect against mucosal challenge with SHIV. Induction of such long HCDR3 antibodies may be critical to the design of an effective vaccine strategy for HIV and other pathogens, however it is unclear at present how to induce such antibodies. Here, we present genetic evidence that human peripheral blood antibodies containing long HCDR3s are not primarily generated by insertions introduced during the somatic hypermutation process. Instead, they are typically formed by processes occurring as part of the original recombination event. Thus, the response of B cells encoding antibodies with long HCDR3s results from selection of unusual clones from the naïve repertoire rather than through accumulation of insertions. These antibodies typically use a small subset of D and J gene segments that are particularly suited to encoding long HCDR3s, resulting in the incorporation of highly conserved genetic elements in the majority of antibody sequences encoding long HCDR3s.
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56
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Chen W, Dimitrov DS. Monoclonal antibody-based candidate therapeutics against HIV type 1. AIDS Res Hum Retroviruses 2012; 28:425-34. [PMID: 21827278 DOI: 10.1089/aid.2011.0226] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Treatment of HIV-1 infection has been highly successful with small molecule drugs. However, resistance still develops. In addition, long-term use can lead to toxicity with unpredictable effects on health. Finally, current drugs do not lead to HIV-1 eradication. The presence of the virus leads to chronic inflammation, which can result in increased morbidity and mortality after prolonged periods of infection. Monoclonal antibodies (mAbs) have been highly successful during the past two decades for therapy of many diseases, primarily cancers and immune disorders. They are relatively safe, especially human mAbs that have evolved in humans at high concentrations to fight diseases and long-term use may not lead to toxicities. Several broadly neutralizing mAbs (bnmAbs) against HIV-1 can protect animals but are not effective when used for therapy of an established infection. We have hypothesized that HIV-1 has evolved strategies to effectively escape neutralization by full-size antibodies in natural infections but not by smaller antibody fragments. Therefore, a promising direction of research is to discover and exploit antibody fragments as potential candidate therapeutics against HIV-1. Here we review several bnmAbs and engineered antibody domains (eAds), their in vitro and in vivo antiviral efficacy, mechanisms used by HIV-1 to escape them, and strategies that could be effective to develop more powerful mAb-based HIV-1 therapeutics.
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Affiliation(s)
- Weizao Chen
- Protein Interactions Group, Center for Cancer Research Nanobiology Program, National Cancer Institute (NCI)-Frederick, National Institutes of Health (NIH), Frederick, Maryland
| | - Dimiter S. Dimitrov
- Protein Interactions Group, Center for Cancer Research Nanobiology Program, National Cancer Institute (NCI)-Frederick, National Institutes of Health (NIH), Frederick, Maryland
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57
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Hessell AJ, Haigwood NL. Neutralizing antibodies and control of HIV: moves and countermoves. Curr HIV/AIDS Rep 2012; 9:64-72. [PMID: 22203469 DOI: 10.1007/s11904-011-0105-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
It is now evident that powerful antibodies directed to conserved regions of HIV-1 envelope protein develop during chronic infection in some individuals and that these antibodies can neutralize a broad array of diverse isolates in vitro, so termed broadly neutralizing antibodies (bNAbs). A great deal of effort is directed internationally at understanding the ontogeny of NAbs during infection as well as in designing and testing immunogens that can elicit bNAbs in animal models and in humans. Given the parrying tactics of Env, multiple approaches, along with high-resolution structural studies, will be needed to reach a degree of understanding sufficient to design an effective vaccine. We discuss and note here some of the most important recent advances in our knowledge of how neutralizing antibodies develop in vivo, the recent discovery of extremely powerful neutralizing monoclonal antibodies isolated from natural infection, enhanced methodologies that have accelerated discoveries on both fronts, and the progress made in eliciting potent NAbs with limited breadth by vaccination.
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Affiliation(s)
- Ann J Hessell
- Pathobiology and Immunology Division, Oregon National Primate Center, Oregon Health and Science University, Beaverton, OR 97006, USA
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58
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Wetzel R. Physical chemistry of polyglutamine: intriguing tales of a monotonous sequence. J Mol Biol 2012; 421:466-90. [PMID: 22306404 DOI: 10.1016/j.jmb.2012.01.030] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 01/18/2012] [Indexed: 01/08/2023]
Abstract
Polyglutamine (polyQ) sequences of unknown normal function are present in a significant number of proteins, and their repeat expansion is associated with a number of genetic neurodegenerative diseases. PolyQ solution structure and properties are important not only because of the normal and abnormal biology associated with these sequences but also because they represent an interesting case of a biologically relevant homopolymer. As the common thread in expanded polyQ repeat diseases, it is important to understand the structure and properties of simple polyQ sequences. At the same time, experience has shown that sequences attached to polyQ, whether in artificial constructs or in disease proteins, can influence structure and properties. The two major contenders for the molecular source of the neurotoxicity implicit in polyQ expansion within disease proteins are a populated toxic conformation in the monomer ensemble and a toxic aggregated species. This review summarizes experimental and computational studies on the solution structure and aggregation properties of both simple and complex polyQ sequences, and their repeat-length dependence. As a representative of complex polyQ proteins, the behavior of huntingtin N-terminal fragments, such as exon-1, receives special attention.
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Affiliation(s)
- Ronald Wetzel
- Department of Structural Biology and Pittsburgh Institute for Neurodegenerative Disease, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA.
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59
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Van Regenmortel MHV. Limitations to the structure-based design of HIV-1 vaccine immunogens. J Mol Recognit 2012; 24:741-53. [PMID: 21812050 DOI: 10.1002/jmr.1116] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In spite of 25 years of intensive research, no effective human immunodeficiency virus type 1 (HIV-1) vaccine has yet been developed. One reason for this is that investigators have concentrated mainly on the structural analysis of HIV-1 antigens because they assumed that it should be possible to deduce vaccine-relevant immunogens from the structure of viral antigens bound to neutralizing monoclonal antibodies. This unwarranted assumption arises from misconceptions regarding the nature of protein epitopes and from the belief that it is justified to extrapolate from the antigenicity to the immunogenicity of proteins. Although the structure of the major HIV-1 antigenic sites has been elucidated, this knowledge has been of little use for designing an HIV-1 vaccine. Little attention has been given to the fact that protective immune responses tend to be polyclonal and involve antibodies directed to several different epitopes. It is concluded that only trial and error, empirical investigations using numerous immunization protocols may eventually allow us to identify which mixtures of immunogens are likely to be the best candidates for an HIV-1 vaccine.
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Cerasoli E, Ravi J, Gregor C, Hussain R, Siligardi G, Martyna G, Crain J, Ryadnov MG. Membrane mediated regulation in free peptides of HIV-1 gp41: minimal modulation of the hemifusion phase. Phys Chem Chem Phys 2012; 14:1277-85. [DOI: 10.1039/c1cp23155c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Stanfield RL, Julien JP, Pejchal R, Gach JS, Zwick MB, Wilson IA. Structure-based design of a protein immunogen that displays an HIV-1 gp41 neutralizing epitope. J Mol Biol 2011; 414:460-76. [PMID: 22033480 PMCID: PMC3245871 DOI: 10.1016/j.jmb.2011.10.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Revised: 10/03/2011] [Accepted: 10/10/2011] [Indexed: 01/21/2023]
Abstract
Antibody Z13e1 is a relatively broadly neutralizing anti-human immunodeficiency virus type 1 antibody that recognizes the membrane-proximal external region (MPER) of the human immunodeficiency virus type 1 envelope glycoprotein gp41. Based on the crystal structure of an MPER epitope peptide in complex with Z13e1 Fab, we identified an unrelated protein, interleukin (IL)-22, with a surface-exposed region that is structurally homologous in its backbone to the gp41 Z13e1 epitope. By grafting the gp41 Z13e1 epitope sequence onto the structurally homologous region in IL-22, we engineered a novel protein (Z13-IL22-2) that contains the MPER epitope sequence for use as a potential immunogen and as a reagent for the detection of Z13e1-like antibodies. The Z13-IL22-2 protein binds Fab Z13e1 with a K(d) of 73 nM. The crystal structure of Z13-IL22-2 in complex with Fab Z13e1 shows that the epitope region is faithfully replicated in the Fab-bound scaffold protein; however, isothermal calorimetry studies indicate that Fab binding to Z13-IL22-2 is not a lock-and-key event, leaving open the question of whether conformational changes upon binding occur in the Fab, in Z13-IL-22, or in both.
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Affiliation(s)
- Robyn L Stanfield
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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62
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Binding of anti-membrane-proximal gp41 monoclonal antibodies to CD4-liganded and -unliganded human immunodeficiency virus type 1 and simian immunodeficiency virus virions. J Virol 2011; 86:1820-31. [PMID: 22090143 DOI: 10.1128/jvi.05489-11] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The broadly neutralizing monoclonal antibodies (MAbs) 4E10, 2F5, and Z13e1 target membrane-proximal external region (MPER) epitopes of HIV-1 gp41 in a manner that remains controversial. The requirements for initial lipid bilayer binding and/or CD4 ligation have been proposed. To further investigate these issues, we probed for binding of these MAbs to human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV) virions with protein A-conjugated gold (PAG) nanoparticles using negative-stain electron microscopy. We found moderate levels of PAG associated with unliganded HIV-1 and SIV virions incubated with the three MAbs. Significantly higher levels of PAG were associated with CD4-liganded HIV-1 (epitope-positive) but not SIV (epitope-negative) virions. A chimeric SIV virion displaying the HIV-1 4E10 epitope also showed significantly higher PAG association after CD4 ligation and incubation with 4E10. MAbs accumulated rapidly on CD4-liganded virions and slowly on unliganded virions, although both reached similar levels in time. Anti-MPER epitope-specific binding was stable to washout. Virions incubated with an irrelevant MAb or CD4-only (no MAb) showed negligible PAG association, as did a vesicle-rich fraction devoid of virions. Preincubation with Fab 4E10 inhibited both specific and nonspecific 4E10 IgG binding. Our data provide evidence for moderate association of anti-MPER MAbs to viral surfaces but not lipid vesicles, even in the absence of cognate epitopes. Significantly greater MAb interaction occurs in epitope-positive virions following long incubation or CD4 ligation. These findings are consistent with a two-stage binding model where these anti-MPER MAbs bind first to the viral lipid bilayer and then to the MPER epitopes following spontaneous or induced exposure.
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63
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Kim M, Sun ZYJ, Rand KD, Shi X, Song L, Cheng Y, Fahmy AF, Majumdar S, Ofek G, Yang Y, Kwong PD, Wang JH, Engen JR, Wagner G, Reinherz EL. Antibody mechanics on a membrane-bound HIV segment essential for GP41-targeted viral neutralization. Nat Struct Mol Biol 2011; 18:1235-43. [PMID: 22002224 PMCID: PMC3253551 DOI: 10.1038/nsmb.2154] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 08/09/2011] [Indexed: 11/08/2022]
Abstract
Broadly neutralizing antibodies such as 2F5 are directed against the membrane-proximal external region (MPER) of HIV-1 GP41 and recognize well-defined linear core sequences. These epitopes can be engrafted onto protein scaffolds to serve as immunogens with high structural fidelity. Although antibodies that bind to this core GP41 epitope can be elicited, they lack neutralizing activity. To understand this paradox, we used biophysical methods to investigate the binding of human 2F5 to the MPER in a membrane environment, where it resides in vivo. Recognition is stepwise, through a paratope more extensive than core binding site contacts alone, and dynamic rearrangement through an apparent scoop-like movement of heavy chain complementarity-determining region 3 (CDRH3) is essential for MPER extraction from the viral membrane. Core-epitope recognition on the virus requires the induction of conformational changes in both the MPER and the paratope. Hence, target neutralization through this lipid-embedded viral segment places stringent requirements on the plasticity of the antibody combining site.
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Affiliation(s)
- Mikyung Kim
- Laboratory of Immunobiology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
- Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Zhen-Yu J. Sun
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Kasper D. Rand
- Department of Chemistry & Chemical Biology and The Barnett Institute of Chemical & Biological Analysis, Northeastern University, Boston, MA 02115, USA
| | - Xiaomeng Shi
- Department of Chemistry & Chemical Biology and The Barnett Institute of Chemical & Biological Analysis, Northeastern University, Boston, MA 02115, USA
| | - Likai Song
- Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
- Cancer Vaccine Center, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA
| | - Yuxing Cheng
- Laboratory of Immunobiology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
- PhD Program in Biological Sciences in Public Health, Harvard School of Public Health, Boston, MA 02115, USA
| | - Amr F. Fahmy
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Shreoshi Majumdar
- Laboratory of Immunobiology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Gilad Ofek
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yongping Yang
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Peter D. Kwong
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jia-huai Wang
- Laboratory of Immunobiology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
- Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - John R. Engen
- Department of Chemistry & Chemical Biology and The Barnett Institute of Chemical & Biological Analysis, Northeastern University, Boston, MA 02115, USA
| | - Gerhard Wagner
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Ellis L. Reinherz
- Laboratory of Immunobiology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
- Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
- Cancer Vaccine Center, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
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64
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Morris L, Chen X, Alam M, Tomaras G, Zhang R, Marshall DJ, Chen B, Parks R, Foulger A, Jaeger F, Donathan M, Bilska M, Gray ES, Abdool Karim SS, Kepler TB, Whitesides J, Montefiori D, Moody MA, Liao HX, Haynes BF. Isolation of a human anti-HIV gp41 membrane proximal region neutralizing antibody by antigen-specific single B cell sorting. PLoS One 2011; 6:e23532. [PMID: 21980336 PMCID: PMC3184076 DOI: 10.1371/journal.pone.0023532] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2011] [Accepted: 07/19/2011] [Indexed: 11/19/2022] Open
Abstract
Broadly neutralizing antibodies are not commonly produced in HIV-1 infected individuals nor by experimental HIV-1 vaccines. When these antibodies do occur, it is important to be able to isolate and characterize them to provide clues for vaccine design. CAP206 is a South African subtype C HIV-1-infected individual previously shown to have broadly neutralizing plasma antibodies targeting the envelope gp41 distal membrane proximal external region (MPER). We have now used a fluoresceinated peptide tetramer antigen with specific cell sorting to isolate a human neutralizing monoclonal antibody (mAb) against the HIV-1 envelope gp41 MPER. The isolated recombinant mAb, CAP206-CH12, utilized a portion of the distal MPER (HXB2 amino acid residues, 673-680) and neutralized a subset of HIV-1 pseudoviruses sensitive to CAP206 plasma antibodies. Interestingly, this mAb was polyreactive and used the same germ-line variable heavy (V(H)1-69) and variable kappa light chain (V(K)3-20) gene families as the prototype broadly neutralizing anti-MPER mAb, 4E10 (residues 672-680). These data indicate that there are multiple immunogenic targets in the C-terminus of the MPER of HIV-1 gp41 envelope and suggests that gp41 neutralizing epitopes may interact with a restricted set of naive B cells during HIV-1 infection.
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Affiliation(s)
- Lynn Morris
- Duke Human Vaccine Institute and Departments of Medicine, Surgery and Immunology, Duke University School of Medicine, Durham, North Carolina, United States of America.
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65
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Ingale S, Gach JS, Zwick MB, Dawson PE. Synthesis and analysis of the membrane proximal external region epitopes of HIV-1. J Pept Sci 2011; 16:716-22. [PMID: 21104968 DOI: 10.1002/psc.1325] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The membrane proximal external region (MPER) of gp41 abuts the viral membrane at the base of HIV-1 envelope glycoprotein spikes. The MPER is highly conserved and is rich in Trp and other lipophilic residues. The MPER is also required for the infection of host cells by HIV-1 and is the target of the broadly neutralizing antibodies, 4E10, 2F5, and Z13e1. These neutralizing antibodies are valuable tools for understanding relevant conformations of the MPER and for studying HIV-1 neutralization, but multiple approaches used to elicit MPER binding antibodies with similar neutralization properties have failed. Here we report our efforts to mimic the MPER using linear as well as constrained peptides. Unnatural amino acids were also introduced into the core epitope of 4E10 to probe requirements of antibody binding. Peptide analogs with C-terminal Api or Aib residues designed to be helical transmembrane (TM) domain surrogates exhibit enhanced binding to the 4E10 and Z13e1 antibodies. However, we find that placement of constrained amino acids at nonbinding sites within the core epitope significantly reduce binding. These results are relevant to an understanding of native MPER structure on HIV-1, and form a basis for a chemical synthesis approach to mimic MPER stricture and to construct an MPER-based vaccine.
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Affiliation(s)
- Sampat Ingale
- Department of Chemistry and Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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66
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Abstract
OBJECTIVES 2F5 and 4E10 are two broadly neutralizing monoclonal antibodies (mAbs) targeting the membrane proximal external region (MPER) of HIV-1 gp41 envelope protein. This region, which contacts the viral membrane, is highly conserved and has been regarded as a promising target for vaccine development. We aimed to clarify the basis of 2F5 and 4E10 molecular interactions with epitope cores in MPER and lipid bilayers. DESIGN Microscopy-based approaches were used to infer and quantify the effects of both mAbs on membranes, in the presence and absence of the epitope cores. Supported lipid bilayers (SLBs), with and without phase separation, were used as membrane models. Fluorescent-labeled and nonlabeled MPER-derived peptides containing both 2F5 and 4E10 epitopes were used. METHODS mAbs 2F5 and 4E10 membrane interactions, in the presence or absence of MPER-derived peptides, were evaluated by combined atomic force and confocal microscopies. RESULTS Both mAbs form lipid-segregated aggregates on SLBs and do not induce other significant membrane perturbations. Furthermore, the affinity of MPER toward membranes is differently affected by both mAbs and correlates with the mAbs-epitope core lipid interactions. 2F5 is able to dock the MPER peptide on the membrane, whereas 4E10 extracts the MPER from the lipid bilayer. CONCLUSION The results reveal the molecular details underneath 2F5/4E10 membrane-epitope binding and a model is proposed to explain the differential mAbs neutralization efficacies, which relates to the exposure of the epitopes in the lipid bilayers and the role of the lipids in mAb-epitope binding.
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67
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Gregor CR, Cerasoli E, Tulip PR, Ryadnov MG, Martyna GJ, Crain J. Autonomous folding in the membrane proximal HIV peptide gp41659–671: pH tuneability at micelle interfaces. Phys Chem Chem Phys 2011; 13:127-35. [DOI: 10.1039/c0cp01502d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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68
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A nonself sugar mimic of the HIV glycan shield shows enhanced antigenicity. Proc Natl Acad Sci U S A 2010; 107:17107-12. [PMID: 20852065 DOI: 10.1073/pnas.1002717107] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Antibody 2G12 uniquely neutralizes a broad range of HIV-1 isolates by binding the high-mannose glycans on the HIV-1 surface glycoprotein, gp120. Antigens that resemble these natural epitopes of 2G12 would be highly desirable components for an HIV-1 vaccine. However, host-produced (self)-carbohydrate motifs have been unsuccessful so far at eliciting 2G12-like antibodies that cross-react with gp120. Based on the surprising observation that 2G12 binds nonproteinaceous monosaccharide D-fructose with higher affinity than D-mannose, we show here that a designed set of nonself, synthetic monosaccharides are potent antigens. When introduced to the terminus of the D1 arm of protein glycans recognized by 2G12, their antigenicity is significantly enhanced. Logical variation of these unnatural sugars pinpointed key modifications, and the molecular basis of this increased antigenicity was elucidated using high-resolution crystallographic analyses. Virus-like particle protein conjugates containing such nonself glycans are bound more tightly by 2G12. As immunogens they elicit higher titers of antibodies than those immunogenic conjugates containing the self D1 glycan motif. These antibodies generated from nonself immunogens also cross-react with this self motif, which is found in the glycan shield, when it is presented in a range of different conjugates and glycans. However, these antibodies did not bind this glycan motif when present on gp120.
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69
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Shi W, Bohon J, Han DP, Habte H, Qin Y, Cho MW, Chance MR. Structural characterization of HIV gp41 with the membrane-proximal external region. J Biol Chem 2010; 285:24290-8. [PMID: 20525690 PMCID: PMC2911339 DOI: 10.1074/jbc.m110.111351] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 05/05/2010] [Indexed: 11/06/2022] Open
Abstract
Human immunodeficiency virus, type 1 (HIV-1) envelope glycoprotein (gp120/gp41) plays a critical role in virus infection and pathogenesis. Three of the six monoclonal antibodies considered to have broadly neutralizing activities (2F5, 4E10, and Z13e1) bind to the membrane-proximal external region (MPER) of gp41. This makes the MPER a desirable template for developing immunogens that can elicit antibodies with properties similar to these monoclonal antibodies, with a long term goal of developing antigens that could serve as novel HIV vaccines. In order to provide a structural basis for rational antigen design, an MPER construct, HR1-54Q, was generated for x-ray crystallographic and x-ray footprinting studies to provide both high resolution atomic coordinates and verification of the solution state of the antigen, respectively. The crystal structure of HR1-54Q reveals a trimeric, coiled-coil six-helical bundle, which probably represents a postfusion form of gp41. The MPER portion extends from HR2 in continuation of a slightly bent long helix and is relatively flexible. The structures observed for the 2F5 and 4E10 epitopes agree well with existing structural data, and enzyme-linked immunosorbent assays indicate that the antigen binds well to antibodies that recognize the above epitopes. Hydroxyl radical-mediated protein footprinting of the antigen in solution reveals specifically protected and accessible regions consistent with the predictions based on the trimeric structure from the crystallographic data. Overall, the HR1-54Q antigen, as characterized by crystallography and footprinting, represents a postfusion, trimeric form of HIV gp41, and its structure provides a rational basis for gp41 antigen design suitable for HIV vaccine development.
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Affiliation(s)
- Wuxian Shi
- Center for Synchrotron Biosciences, Case Western Reserve University, Cleveland, OH 44106, USA.
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70
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Abstract
Individuals infected with HIV-1 and nearly everyone vaccinated with HIV-1 vaccines will, in time, generate antibodies against viral proteins. These antibodies do not resolve natural infection, and vaccine candidates that successfully stimulate the production of high titers of neutralizing antibodies have failed to protect against infection. In spite of this, antibodies continue to be a focus of vaccine research. One reason for the continued interest in antibodies is the failure of a vaccine engineered to generate cell-mediated immunity against HIV. Successful protective immunity against most intracellular pathogens involves several arms of the immune response. A successful vaccine should also stimulate both protective cell-mediated immunity and specific antibody. Efforts should be directed toward making a vaccine that will stimulate the production of 1) more antibody, 2) more broadly cross-reactive neutralizing antibody (broadly neutralizing antibodies), and 3) antibody with a particular functional activity (antibody-dependent cell-mediated cytotoxicity; catalytic antibodies).
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71
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Structure and function of broadly reactive antibody PG16 reveal an H3 subdomain that mediates potent neutralization of HIV-1. Proc Natl Acad Sci U S A 2010; 107:11483-8. [PMID: 20534513 DOI: 10.1073/pnas.1004600107] [Citation(s) in RCA: 165] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Development of an effective vaccine against HIV-1 will likely require elicitation of broad and potent neutralizing antibodies against the trimeric surface envelope glycoprotein (Env). Monoclonal antibodies (mAbs) PG9 and PG16 neutralize approximately 80% of HIV-1 isolates across all clades with extraordinary potency and target novel epitopes preferentially expressed on Env trimers. As these neutralization properties are ideal for a vaccine-elicited antibody response to HIV-1, their structural basis was investigated. The crystal structure of the antigen-binding fragment (Fab) of PG16 at 2.5 A resolution revealed its unusually long, 28-residue, complementarity determining region (CDR) H3 forms a unique, stable subdomain that towers above the antibody surface. A 7-residue "specificity loop" on the "hammerhead" subdomain was identified that, when transplanted from PG16 to PG9 and vice versa, accounted for differences in the fine specificity and neutralization of these two mAbs. The PG16 electron density maps also revealed that a CDR H3 tyrosine was sulfated, which was confirmed for both PG9 (doubly) and PG16 (singly) by mass spectral analysis. We further showed that tyrosine sulfation plays a role in binding and neutralization. An N-linked glycan modification is observed in the variable light chain, but not required for antigen recognition. Further, the crystal structure of the PG9 light chain at 3.0 A facilitated homology modeling to support the presence of these unusual features in PG9. Thus, PG9 and PG16 use unique structural features to mediate potent neutralization of HIV-1 that may be of utility in antibody engineering and for high-affinity recognition of a variety of therapeutic targets.
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72
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Buzon V, Natrajan G, Schibli D, Campelo F, Kozlov MM, Weissenhorn W. Crystal structure of HIV-1 gp41 including both fusion peptide and membrane proximal external regions. PLoS Pathog 2010; 6:e1000880. [PMID: 20463810 PMCID: PMC2865522 DOI: 10.1371/journal.ppat.1000880] [Citation(s) in RCA: 212] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2010] [Accepted: 03/25/2010] [Indexed: 11/18/2022] Open
Abstract
The HIV-1 envelope glycoprotein (Env) composed of the receptor binding domain gp120 and the fusion protein subunit gp41 catalyzes virus entry and is a major target for therapeutic intervention and for neutralizing antibodies. Env interactions with cellular receptors trigger refolding of gp41, which induces close apposition of viral and cellular membranes leading to membrane fusion. The energy released during refolding is used to overcome the kinetic barrier and drives the fusion reaction. Here, we report the crystal structure at 2 A resolution of the complete extracellular domain of gp41 lacking the fusion peptide and the cystein-linked loop. Both the fusion peptide proximal region (FPPR) and the membrane proximal external region (MPER) form helical extensions from the gp41 six-helical bundle core structure. The lack of regular coiled-coil interactions within FPPR and MPER splay this end of the structure apart while positioning the fusion peptide towards the outside of the six-helical bundle and exposing conserved hydrophobic MPER residues. Unexpectedly, the section of the MPER, which is juxtaposed to the transmembrane region (TMR), bends in a 90 degrees-angle sideward positioning three aromatic side chains per monomer for membrane insertion. We calculate that this structural motif might facilitate the generation of membrane curvature on the viral membrane. The presence of FPPR and MPER increases the melting temperature of gp41 significantly in comparison to the core structure of gp41. Thus, our data indicate that the ordered assembly of FPPR and MPER beyond the core contributes energy to the membrane fusion reaction. Furthermore, we provide the first structural evidence that part of MPER will be membrane inserted within trimeric gp41. We propose that this framework has important implications for membrane bending on the viral membrane, which is required for fusion and could provide a platform for epitope and lipid bilayer recognition for broadly neutralizing gp41 antibodies.
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Affiliation(s)
- Victor Buzon
- Unit of Virus Host Cell Interactions (UVHCI) UMI 3265 Université Joseph Fourier-EMBL-CNRS, Grenoble, France
| | - Ganesh Natrajan
- Unit of Virus Host Cell Interactions (UVHCI) UMI 3265 Université Joseph Fourier-EMBL-CNRS, Grenoble, France
| | - David Schibli
- Unit of Virus Host Cell Interactions (UVHCI) UMI 3265 Université Joseph Fourier-EMBL-CNRS, Grenoble, France
| | - Felix Campelo
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Michael M. Kozlov
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Winfried Weissenhorn
- Unit of Virus Host Cell Interactions (UVHCI) UMI 3265 Université Joseph Fourier-EMBL-CNRS, Grenoble, France
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73
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Leaman DP, Kinkead H, Zwick MB. In-solution virus capture assay helps deconstruct heterogeneous antibody recognition of human immunodeficiency virus type 1. J Virol 2010; 84:3382-95. [PMID: 20089658 PMCID: PMC2838137 DOI: 10.1128/jvi.02363-09] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Accepted: 01/06/2010] [Indexed: 01/27/2023] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) on whole virions is heterogeneous, so molecular analysis of Env with monoclonal antibodies (MAbs) is challenging. Virus capture assays (VCAs) involving immobilized MAbs are typically used, but these assays suffer from immobilization artifacts and do not provide binding constants. Furthermore, we show here that certain HIV-1 neutralizing MAbs, including 2G12, 4E10, 2F5, Z13e1, and D5, will capture virion particles completely devoid of Env. We modified the VCA such that MAbs and virions are incubated in solution, and unbound MAbs are removed prior to the capture step. This modification nearly eliminated evidence of Env-independent binding by MAbs to virions and allowed determination of apparent affinity constants in solution. Three important qualitative observations were further revealed. First, neutralizing MAbs 2F5, 4E10, and Z13e1 against the membrane-proximal external region (MPER) of HIV-1 gp41 were found to capture virions efficiently only if a significant amount of uncleaved gp160 or synthetic MPER peptide was present. Second, we show how non-native forms of Env vary by Env genotype and that Env from HIV-1(JR-FL) is more homogeneously trimeric than that from HIV-1(JR-CSF). Third, we determined that Env containing all or parts of gp41, including uncleaved gp160, binds spontaneously to free virions. This exogenous Env is an indiscriminate molecular "bridge" between Env-specific Ab and virions and can affect VCA analyses, particularly using pseudotyped virions. Heterogeneity in Env from endogenous and exogenous sources might also subvert humoral immunity to HIV-1, so in-solution VCAs may help to dissect this heterogeneity for vaccine design purposes.
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Affiliation(s)
- Daniel P. Leaman
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California 92037
| | - Heather Kinkead
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California 92037
| | - Michael B. Zwick
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California 92037
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74
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Rational antibody-based HIV-1 vaccine design: current approaches and future directions. Curr Opin Immunol 2010; 22:358-66. [PMID: 20299194 DOI: 10.1016/j.coi.2010.02.012] [Citation(s) in RCA: 172] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Accepted: 02/17/2010] [Indexed: 10/19/2022]
Abstract
Many antiviral vaccines elicit neutralizing antibodies as a correlate of protection. For HIV, given the huge variability of the virus, it is widely believed that the induction of a broadly neutralizing antibody (bNAb) response will be crucial in a successful vaccine against the virus. Unfortunately, despite many efforts, the development of an immunogen that elicits bNAbs remains elusive. However, recent structural studies of HIV-1 Env proteins, generation of novel bNAbs, maturation of technologies for the isolation of further antibodies, insights into the requirements for antibody-mediated protection, and novel vaccination approaches are providing grounds for renewed optimism.
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75
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Antigenic characteristics of rhinovirus chimeras designed in silico for enhanced presentation of HIV-1 gp41 epitopes [corrected]. J Mol Biol 2010; 397:752-66. [PMID: 20138057 DOI: 10.1016/j.jmb.2010.01.064] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Revised: 01/26/2010] [Accepted: 01/27/2010] [Indexed: 11/21/2022]
Abstract
The development of an effective AIDS vaccine remains the most promising long-term strategy to combat human immunodeficiency virus (HIV)/AIDS. Here, we report favorable antigenic characteristics of vaccine candidates isolated from a combinatorial library of human rhinoviruses displaying the ELDKWA epitope of the gp41 glycoprotein of HIV-1. The design principles of this library emerged from the application of molecular modeling calculations in conjunction with our knowledge of previously obtained ELDKWA-displaying chimeras, including knowledge of a chimera with one of the best 2F5-binding characteristics obtained to date. The molecular modeling calculations identified the energetic and structural factors affecting the ability of the epitope to assume conformations capable of fitting into the complementarity determining region of the ELDKWA-binding, broadly neutralizing human mAb 2F5. Individual viruses were isolated from the library following competitive immunoselection and were tested using ELISA and fluorescence quenching experiments. Dissociation constants obtained using both techniques revealed that some of the newly isolated chimeras bind 2F5 with greater affinity than previously identified chimeric rhinoviruses. Molecular dynamics simulations of two of these same chimeras confirmed that their HIV inserts were partially preorganized for binding, which is largely responsible for their corresponding gains in binding affinity. The study illustrates the utility of combining structure-based experiments with computational modeling approaches for improving the odds of selecting vaccine component designs with preferred antigenic characteristics. The results obtained also confirm the flexibility of HRV as a presentation vehicle for HIV epitopes and the potential of this platform for the development of vaccine components against AIDS.
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76
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Kanduc D. The self/nonself issue: A confrontation between proteomes. SELF NONSELF 2010; 1:255-258. [PMID: 21487482 DOI: 10.4161/self.1.3.11897] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Accepted: 01/29/2010] [Indexed: 01/09/2023]
Abstract
Defining self and nonself is the most compelling challenge in science today, at the basis of the numerous questions that remain unanswered in the immunology-pathology-therapy debate. The generation of the antibody repertoire, the complicated scenario offered by tolerance and autoimmunity, natural auto-antibodies and their relationship to autoimmune diseases, and positive and negative selection are only a few examples of the unresolved immunological questions. In this context, we proposed that sequence similarity to the host proteome modulates antigen peptide recognition and immunogenicity. Using the available proteome assemblies of viruses, bacteria and higher vertebrates, and applying the low-similarity criterion, we are systematically defining the proteomic similarity of B-cell epitopes already validated experimentally. Here, we report further data documenting that a low similarity to the host proteome is the common property that defines the immunological "nonself" nature of antigenic sequences in cancer, autoimmunity, infectious diseases and allergy.
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Affiliation(s)
- Darja Kanduc
- Department of Biochemistry and Molecular Biology; University of Bari; Bari, Italy
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77
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Aromatic residues at the edge of the antibody combining site facilitate viral glycoprotein recognition through membrane interactions. Proc Natl Acad Sci U S A 2010; 107:1529-34. [PMID: 20080706 DOI: 10.1073/pnas.0909680107] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The broadly neutralizing anti-HIV antibody 4E10 recognizes an epitope very close to the virus membrane on the glycoprotein gp41. It was previously shown that epitope recognition improves in a membrane context and that 4E10 binds directly, albeit weakly, to lipids. Furthermore, a crystal structure of Fab 4E10 complexed to an epitope peptide revealed that the centrally placed, protruding H3 loop of the antibody heavy chain does not form peptide contacts. To investigate the hypothesis that the H3 loop apex might interact with the viral membrane, two Trp residues in this region were substituted separately or in combination with either Ala or Asp by site-directed mutagenesis. The resultant IgG variants exhibited similar affinities for an epitope peptide as WT 4E10 but lower apparent affinities for both viral membrane mimetic liposomes and Env(-) virus. Variants also exhibited lower apparent affinities for Env(+) virions and failed to significantly neutralize a number of 4E10-sensitive viruses. For the extremely sensitive HXB2 virus, variants did neutralize, but at 37- to >250-fold lower titers than WT 4E10, with Asp substitutions exerting a greater effect on neutralization potency than Ala substitutions. Because reductions in lipid binding reflect trends in neutralization potency, we conclude that Trp residues in the antibody H3 loop enable membrane proximal epitope recognition through favorable lipid interactions. The requirement for lipophilic residues such as Trp adjacent to the antigen binding site may explain difficulties in eliciting 4E10-like neutralizing antibody responses by immunization and helps define a unique motif for antibody recognition of membrane proximal antigens.
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78
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Gray ES, Madiga MC, Moore PL, Mlisana K, Abdool Karim SS, Binley JM, Shaw GM, Mascola JR, Morris L. Broad neutralization of human immunodeficiency virus type 1 mediated by plasma antibodies against the gp41 membrane proximal external region. J Virol 2009; 83:11265-74. [PMID: 19692477 PMCID: PMC2772769 DOI: 10.1128/jvi.01359-09] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Accepted: 08/06/2009] [Indexed: 11/20/2022] Open
Abstract
We identified three cross-neutralizing plasma samples with high-titer anti-membrane proximal external region (MPER) peptide binding antibodies from among 156 chronically human immunodeficiency virus type 1-infected individuals. In order to establish if these antibodies were directly responsible for the observed neutralization breadth, we used MPER-coated magnetic beads to deplete plasmas of these specific antibodies. Depletion of anti-MPER antibodies from BB34, CAP206, and SAC21 resulted in 77%, 68%, and 46% decreases, respectively, in the number of viruses neutralized. Antibodies eluted from the beads showed neutralization profiles similar to those of the original plasmas, with potencies comparable to those of the known anti-MPER monoclonal antibodies (MAbs), 4E10, 2F5, and Z13e1. The anti-MPER neutralizing antibodies in BB34 were present in the immunoglobulin G3 subclass-enriched fraction. Alanine scanning of the MPER showed that the antibodies from these three plasmas had specificities distinct from those of the known MAbs, requiring one to three crucial residues at positions 670, 673, and 674. These data demonstrate the existence of MPER-specific cross-neutralizing antibodies in plasma, although the ability to elicit such potent antiviral antibodies during natural infection appears to be rare. Nevertheless, the identification of three novel antibody specificities within the MPER supports its further study as a promising target for vaccine design.
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Affiliation(s)
- Elin S. Gray
- AIDS Virus Research Unit, National Institute for Communicable Diseases, Johannesburg, South Africa, Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu Natal, Durban, South Africa, Torrey Pines Institute for Molecular Studies, San Diego, California 92121, University of Alabama at Birmingham, Birmingham, Alabama 35294, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Maphuti C. Madiga
- AIDS Virus Research Unit, National Institute for Communicable Diseases, Johannesburg, South Africa, Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu Natal, Durban, South Africa, Torrey Pines Institute for Molecular Studies, San Diego, California 92121, University of Alabama at Birmingham, Birmingham, Alabama 35294, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Penny L. Moore
- AIDS Virus Research Unit, National Institute for Communicable Diseases, Johannesburg, South Africa, Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu Natal, Durban, South Africa, Torrey Pines Institute for Molecular Studies, San Diego, California 92121, University of Alabama at Birmingham, Birmingham, Alabama 35294, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Koleka Mlisana
- AIDS Virus Research Unit, National Institute for Communicable Diseases, Johannesburg, South Africa, Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu Natal, Durban, South Africa, Torrey Pines Institute for Molecular Studies, San Diego, California 92121, University of Alabama at Birmingham, Birmingham, Alabama 35294, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Salim S. Abdool Karim
- AIDS Virus Research Unit, National Institute for Communicable Diseases, Johannesburg, South Africa, Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu Natal, Durban, South Africa, Torrey Pines Institute for Molecular Studies, San Diego, California 92121, University of Alabama at Birmingham, Birmingham, Alabama 35294, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - James M. Binley
- AIDS Virus Research Unit, National Institute for Communicable Diseases, Johannesburg, South Africa, Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu Natal, Durban, South Africa, Torrey Pines Institute for Molecular Studies, San Diego, California 92121, University of Alabama at Birmingham, Birmingham, Alabama 35294, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - George M. Shaw
- AIDS Virus Research Unit, National Institute for Communicable Diseases, Johannesburg, South Africa, Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu Natal, Durban, South Africa, Torrey Pines Institute for Molecular Studies, San Diego, California 92121, University of Alabama at Birmingham, Birmingham, Alabama 35294, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - John R. Mascola
- AIDS Virus Research Unit, National Institute for Communicable Diseases, Johannesburg, South Africa, Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu Natal, Durban, South Africa, Torrey Pines Institute for Molecular Studies, San Diego, California 92121, University of Alabama at Birmingham, Birmingham, Alabama 35294, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Lynn Morris
- AIDS Virus Research Unit, National Institute for Communicable Diseases, Johannesburg, South Africa, Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu Natal, Durban, South Africa, Torrey Pines Institute for Molecular Studies, San Diego, California 92121, University of Alabama at Birmingham, Birmingham, Alabama 35294, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892
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79
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Du SX, Idiart RJ, Mariano EB, Chen H, Jiang P, Xu L, Ostrow KM, Wrin T, Phung P, Binley JM, Petropoulos CJ, Ballantyne JA, Whalen RG. Effect of trimerization motifs on quaternary structure, antigenicity, and immunogenicity of a noncleavable HIV-1 gp140 envelope glycoprotein. Virology 2009; 395:33-44. [PMID: 19815247 DOI: 10.1016/j.virol.2009.07.042] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Revised: 06/01/2009] [Accepted: 07/31/2009] [Indexed: 10/20/2022]
Abstract
The external domains of the HIV-1 envelope glycoprotein (gp120 and the gp41 ectodomain, collectively known as gp140) contain all known viral neutralization epitopes. Various strategies have been used to create soluble trimers of the envelope to mimic the structure of the native viral protein, including mutation of the gp120-gp41 cleavage site, introduction of disulfide bonds, and fusion to heterologous trimerization motifs. We compared the effects on quaternary structure, antigenicity, and immunogenicity of three such motifs: T4 fibritin, a GCN4 variant, and the Escherichia coli aspartate transcarbamoylase catalytic subunit. Fusion of each motif to the C-terminus of a noncleavable JRCSF gp140(-) envelope protein led to enhanced trimerization but had limited effects on the antigenic profile and CD4-binding ability of the trimers. Immunization of rabbits provided no evidence that the trimerized gp140(-) constructs induced significantly improved neutralizing antibodies to several HIV-1 pseudoviruses, compared to gp140 lacking a trimerization motif. However, modest differences in both binding specificity and neutralizing antibody responses were observed among the various immunogens.
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Affiliation(s)
- Sean X Du
- Maxygen, Inc., 515 Galveston Drive, Redwood City, CA 94063, USA
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80
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Crystallographic definition of the epitope promiscuity of the broadly neutralizing anti-human immunodeficiency virus type 1 antibody 2F5: vaccine design implications. J Virol 2009; 83:11862-75. [PMID: 19740978 DOI: 10.1128/jvi.01604-09] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The quest to create a human immunodeficiency virus type 1 (HIV-1) vaccine capable of eliciting broadly neutralizing antibodies against Env has been challenging. Among other problems, one difficulty in creating a potent immunogen resides in the substantial overall sequence variability of the HIV envelope protein. The membrane-proximal region (MPER) of gp41 is a particularly conserved tryptophan-rich region spanning residues 659 to 683, which is recognized by three broadly neutralizing monoclonal antibodies (bnMAbs), 2F5, Z13, and 4E10. In this study, we first describe the variability of residues in the gp41 MPER and report on the invariant nature of 15 out of 25 amino acids comprising this region. Subsequently, we evaluate the ability of the bnMAb 2F5 to recognize 31 varying sequences of the gp41 MPER at a molecular level. In 19 cases, resulting crystal structures show the various MPER peptides bound to the 2F5 Fab'. A variety of amino acid substitutions outside the 664DKW666 core epitope are tolerated. However, changes at the 664DKW666 motif itself are restricted to those residues that preserve the aspartate's negative charge, the hydrophobic alkyl-pi stacking arrangement between the beta-turn lysine and tryptophan, and the positive charge of the former. We also characterize a possible molecular mechanism of 2F5 escape by sequence variability at position 667, which is often observed in HIV-1 clade C isolates. Based on our results, we propose a somewhat more flexible molecular model of epitope recognition by bnMAb 2F5, which could guide future attempts at designing small-molecule MPER-like vaccines capable of eliciting 2F5-like antibodies.
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