1
|
Colin P, Ringe RP, Yasmeen A, Ozorowski G, Ketas TJ, Lee WH, Ward AB, Moore JP, Klasse PJ. Conformational antigenic heterogeneity as a cause of the persistent fraction in HIV-1 neutralization. Retrovirology 2023; 20:9. [PMID: 37244989 DOI: 10.1186/s12977-023-00624-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 05/15/2023] [Indexed: 05/29/2023] Open
Abstract
BACKGROUND Neutralizing antibodies (NAbs) protect against HIV-1 acquisition in animal models and show promise in treatment of infection. They act by binding to the viral envelope glycoprotein (Env), thereby blocking its receptor interactions and fusogenic function. The potency of neutralization is largely determined by affinity. Less well explained is the persistent fraction, the plateau of remaining infectivity at the highest antibody concentrations. RESULTS We observed different persistent fractions for neutralization of pseudovirus derived from two Tier-2 isolates of HIV-1, BG505 (Clade A) and B41 (Clade B): it was pronounced for B41 but not BG505 neutralization by NAb PGT151, directed to the interface between the outer and transmembrane subunits of Env, and negligible for either virus by NAb PGT145 to an apical epitope. Autologous neutralization by poly- and monoclonal NAbs from rabbits immunized with soluble native-like B41 trimer also left substantial persistent fractions. These NAbs largely target a cluster of epitopes lining a hole in the dense glycan shield of Env around residue 289. We partially depleted B41-virion populations by incubating them with PGT145- or PGT151-conjugated beads. Each depletion reduced the sensitivity to the depleting NAb and enhanced it to the other. Autologous neutralization by the rabbit NAbs was decreased for PGT145-depleted and enhanced for PGT151-depleted B41 pseudovirus. Those changes in sensitivity encompassed both potency and the persistent fraction. We then compared soluble native-like BG505 and B41 Env trimers affinity-purified by each of three NAbs: 2G12, PGT145, or PGT151. Surface plasmon resonance showed differences among the fractions in antigenicity, including kinetics and stoichiometry, congruently with the differential neutralization. The large persistent fraction after PGT151 neutralization of B41 was attributable to low stoichiometry, which we explained structurally by clashes that the conformational plasticity of B41 Env causes. CONCLUSION Distinct antigenic forms even of clonal HIV-1 Env, detectable among soluble native-like trimer molecules, are distributed over virions and may profoundly mold neutralization of certain isolates by certain NAbs. Affinity purifications with some antibodies may yield immunogens that preferentially expose epitopes for broadly active NAbs, shielding less cross-reactive ones. NAbs reactive with multiple conformers will together reduce the persistent fraction after passive and active immunization.
Collapse
Affiliation(s)
- Philippe Colin
- Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, 1300 York Avenue, 62 , New York, NY, 10065, USA
- Toulouse Institute for Infectious and Inflammatory Diseases, Infinity, Université de Toulouse, CNRS, INSERM, UPS, Toulouse, France
| | - Rajesh P Ringe
- Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, 1300 York Avenue, 62 , New York, NY, 10065, USA
- Virology Unit, Institute of Microbial Technology, Council of Scientific and Industrial Research (CSIR), Chandigarh, India
| | - Anila Yasmeen
- Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, 1300 York Avenue, 62 , New York, NY, 10065, USA
| | - Gabriel Ozorowski
- Department of Integrative Structural and Computational Biology, Consortium for HIV Vaccine 14 Development (CHAVD), The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Thomas J Ketas
- Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, 1300 York Avenue, 62 , New York, NY, 10065, USA
| | - Wen-Hsin Lee
- Department of Integrative Structural and Computational Biology, Consortium for HIV Vaccine 14 Development (CHAVD), The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Andrew B Ward
- Department of Integrative Structural and Computational Biology, Consortium for HIV Vaccine 14 Development (CHAVD), The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - John P Moore
- Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, 1300 York Avenue, 62 , New York, NY, 10065, USA
| | - P J Klasse
- Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, 1300 York Avenue, 62 , New York, NY, 10065, USA.
| |
Collapse
|
2
|
Patabandige MW, Pfeifer LD, Nguyen HT, Desaire H. Quantitative clinical glycomics strategies: A guide for selecting the best analysis approach. MASS SPECTROMETRY REVIEWS 2022; 41:901-921. [PMID: 33565652 PMCID: PMC8601598 DOI: 10.1002/mas.21688] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 12/13/2020] [Accepted: 01/24/2021] [Indexed: 05/05/2023]
Abstract
Glycans introduce complexity to the proteins to which they are attached. These modifications vary during the progression of many diseases; thus, they serve as potential biomarkers for disease diagnosis and prognosis. The immense structural diversity of glycans makes glycosylation analysis and quantitation difficult. Fortunately, recent advances in analytical techniques provide the opportunity to quantify even low-abundant glycopeptides and glycans derived from complex biological mixtures, allowing for the identification of glycosylation differences between healthy samples and those derived from disease states. Understanding the strengths and weaknesses of different quantitative glycomics analysis methods is important for selecting the best strategy to analyze glycosylation changes in any given set of clinical samples. To provide guidance towards selecting the proper approach, we discuss four widely used quantitative glycomics analysis platforms, including fluorescence-based analysis of released N-linked glycans and three different varieties of MS-based analysis: liquid chromatography (LC)-mass spectrometry (MS) analysis of glycopeptides, matrix-assisted laser desorption ionization-time of flight MS, and LC-ESI-MS analysis of released N-linked glycans. These methods' strengths and weaknesses are compared, particularly associated with the figures of merit that are important for clinical biomarker studies, including: the initial sample requirements, the methods' throughput, sample preparation time, the number of species identified, the methods' utility for isomer separation and structural characterization, method-related challenges associated with quantitation, repeatability, the expertise required, and the cost for each analysis. This review, therefore, provides unique guidance to researchers who endeavor to undertake a clinical glycomics analysis by offering insights on the available analysis technologies.
Collapse
Affiliation(s)
- Milani Wijeweera Patabandige
- Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, KS 66047, United States
| | - Leah D. Pfeifer
- Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, KS 66047, United States
| | - Hanna T. Nguyen
- Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, KS 66047, United States
| | - Heather Desaire
- Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, KS 66047, United States
| |
Collapse
|
3
|
Meier AA, Go EP, Moon HJ, Desaire H, Mure M. Mass Spectrometry-Based Disulfide Mapping of Lysyl Oxidase-like 2. Int J Mol Sci 2022; 23:5879. [PMID: 35682561 PMCID: PMC9180022 DOI: 10.3390/ijms23115879] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 05/20/2022] [Accepted: 05/21/2022] [Indexed: 01/09/2023] Open
Abstract
Lysyl oxidase-like 2 (LOXL2) catalyzes the oxidative deamination of peptidyl lysines and hydroxylysines to promote extracellular matrix remodeling. Aberrant activity of LOXL2 has been associated with organ fibrosis and tumor metastasis. The lysine tyrosylquinone (LTQ) cofactor is derived from Lys653 and Tyr689 in the amine oxidase domain via post-translational modification. Based on the similarity in hydrodynamic radius and radius of gyration, we recently proposed that the overall structures of the mature LOXL2 (containing LTQ) and the precursor LOXL2 (no LTQ) are very similar. In this study, we conducted a mass spectrometry-based disulfide mapping analysis of recombinant LOXL2 in three forms: a full-length LOXL2 (fl-LOXL2) containing a nearly stoichiometric amount of LTQ, Δ1-2SRCR-LOXL2 (SRCR1 and SRCR2 are truncated) in the precursor form, and Δ1-3SRCR-LOXL2 (SRCR1, SRCR2, SRCR3 are truncated) in a mixture of the precursor and the mature forms. We detected a set of five disulfide bonds that is conserved in both the precursor and the mature recombinant LOXL2s. In addition, we detected a set of four alternative disulfide bonds in low abundance that is not associated with the mature LOXL2. These results suggest that the major set of five disulfide bonds is retained post-LTQ formation.
Collapse
Affiliation(s)
| | | | | | - Heather Desaire
- Department of Chemistry, The University of Kansas, Lawrence, KS 66045, USA; (A.A.M.); (E.P.G.); (H.-J.M.)
| | - Minae Mure
- Department of Chemistry, The University of Kansas, Lawrence, KS 66045, USA; (A.A.M.); (E.P.G.); (H.-J.M.)
| |
Collapse
|
4
|
Dual Pathways of Human Immunodeficiency Virus Type 1 Envelope Glycoprotein Trafficking Modulate the Selective Exclusion of Uncleaved Oligomers from Virions. J Virol 2021; 95:JVI.01369-20. [PMID: 33148792 DOI: 10.1128/jvi.01369-20] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/24/2020] [Indexed: 12/14/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) trimer is transported through the secretory pathway to the infected cell surface and onto virion particles. In the Golgi, the gp160 Env precursor is modified by complex sugars and proteolytically cleaved to produce the mature functional Env trimer, which resists antibody neutralization. We observed mostly uncleaved gp160 and smaller amounts of cleaved gp120 and gp41 Envs on the surface of HIV-1-infected or Env-expressing cells; however, cleaved Envs were relatively enriched in virions and virus-like particles (VLPs). This relative enrichment of cleaved Env in VLPs was observed for wild-type Envs, for Envs lacking the cytoplasmic tail, and for CD4-independent, conformationally flexible Envs. On the cell surface, we identified three distinct populations of Envs: (i) the cleaved Env was transported through the Golgi, was modified by complex glycans, formed trimers that cross-linked efficiently, and was recognized by broadly neutralizing antibodies; (ii) a small fraction of Env modified by complex carbohydrates escaped cleavage in the Golgi; and (iii) the larger population of uncleaved Env lacked complex carbohydrates, cross-linked into diverse oligomeric forms, and was recognized by poorly neutralizing antibodies. This last group of more "open" Env oligomers reached the cell surface in the presence of brefeldin A, apparently bypassing the Golgi apparatus. Relative to Envs transported through the Golgi, these uncleaved Envs were counterselected for virion incorporation. By employing two pathways for Env transport to the surface of infected cells, HIV-1 can misdirect host antibody responses toward conformationally flexible, uncleaved Env without compromising virus infectivity.IMPORTANCE The envelope glycoprotein (Env) trimers on the surface of human immunodeficiency virus type 1 (HIV-1) mediate the entry of the virus into host cells and serve as targets for neutralizing antibodies. The cleaved, functional Env is incorporated into virus particles from the surface of the infected cell. We found that an uncleaved form of Env is transported to the cell surface by an unconventional route, but this nonfunctional Env is mostly excluded from the virus. Thus, only one of the pathways by which Env is transported to the surface of infected cells results in efficient incorporation into virus particles, potentially allowing the uncleaved Env to act as a decoy to the host immune system without compromising virus infectivity.
Collapse
|
5
|
Bontempo A, Garcia MM, Rivera N, Cayabyab MJ. A Systematic Approach to HIV-1 Vaccine Immunogen Selection. AIDS Res Hum Retroviruses 2020; 36:762-770. [PMID: 32056466 DOI: 10.1089/aid.2019.0239] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
A tremendous loss of financial and human resources from seven large-scale HIV vaccine efficacy trials suggest a need for a systematic approach to vaccine selection. We conducted a systematic analysis of three important envelope glycoprotein (Env) vaccine candidates: BG505 SOSIP.664, 1086.C gp140, and 1086.C gp120 to determine the most promising by comparing their structure and antigenicity. We found that the BG505 SOSIP trimer and 1086.C gp140 clearly outperformed the 1086.C gp120 monomer. BG505 SOSIP.664 bound the strongest to the most potent and broadest broadly neutralizing antibodies (bnAbs) PG9, PGT145, VRC01, and PGT121. Of interest, although BG505 SOSIP.664 did not bind to the CH58 mAb, 1086.C gp140 bound strongly to this mAb, which belongs to a class of non-neutralizing antibodies that may be protective based on correlates of protection studies of the RV144 HIV vaccine trial. The 1086.C gp120 monomer was the least antigenic of the three vaccine immunogens, binding the weakest to bnAbs and CH58 mAb. Taken together, the evidence provided here combined with previous preclinical immunogenicity and efficacy data strongly argue that the BG505 SOSIP.664 trimer and 1086.C gp140 are likely to be better vaccine immunogens than the monomeric 1086.C gp120, which was just recently tested and shown to be nonefficacious in a phase IIb/III trial. Thus, to best utilize our financial and valuable human resources, we propose a systematic approach by not only comparing structure and antigenicity, but also immunogenicity and efficacy of Env vaccine candidates in the preclinical phase to the selection of only the most promising vaccine candidates for clinical testing.
Collapse
Affiliation(s)
- Alexander Bontempo
- Department of Immunology and Infectious Diseases, Forsyth Institute, Cambridge, Massachusetts, USA
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Maria M. Garcia
- Department of Immunology and Infectious Diseases, Forsyth Institute, Cambridge, Massachusetts, USA
| | - Naylene Rivera
- Department of Immunology and Infectious Diseases, Forsyth Institute, Cambridge, Massachusetts, USA
| | - Mark J. Cayabyab
- Department of Immunology and Infectious Diseases, Forsyth Institute, Cambridge, Massachusetts, USA
| |
Collapse
|
6
|
Ximba P, Chapman R, Meyers AE, Margolin E, van Diepen MT, Williamson AL, Rybicki EP. Characterization and Immunogenicity of HIV Envelope gp140 Zera ® Tagged Antigens. Front Bioeng Biotechnol 2020; 8:321. [PMID: 32328488 PMCID: PMC7160593 DOI: 10.3389/fbioe.2020.00321] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 03/24/2020] [Indexed: 11/13/2022] Open
Abstract
HIV-1 envelope glycoprotein (Env) remains the most relevant target for the elicitation of functional antibodies to HIV by vaccination. However, soluble Env antigens often do not elicit the desired immune responses. Delivering subunit antigens on particulate nanoparticles is an established approach to improve their immunogenicity. In this study the sequence encoding Zera®, a proline-rich domain derived from the γ-zein storage protein, was fused to either the C- or N-terminus of the superinfecting HIV-1 CAP256 gp140 envelope: Zera® generally induces the formation of protein bodies (PBs), which can significantly improve both the immunogenicity and yields of the partner protein. The expression of gp140-Zera® and Zera®-gp140 (N- and C-terminal fusions respectively) in mammalian cells was confirmed by western blot analysis and immunostaining. However, isopycnic ultracentrifugation showed that neither gp140-Zera® nor Zera®-gp140 accumulated in characteristic electron-dense PBs. gp140-Zera® elicited higher binding antibody titers in rabbits to autologous gp140 and V1V2 scaffold than Zera®-gp140. Rabbit anti-gp140-Zera® sera also had significantly higher Tier 1A neutralizing antibody titers than anti-Zera®-gp140 sera. Neither gp140-Zera® nor Zera®-gp140-specific sera neutralized Tier 1B or autologous Tier 2 viruses. These results showed that HIV-1 gp140 tagged with Zera® at either the N- or C-termini elicited high titers of gp140 and V1V2 binding antibodies, and low levels of Tier 1 neutralizing antibodies in rabbits.
Collapse
Affiliation(s)
- Phindile Ximba
- Division of Medical Virology, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Biopharming Research Unit, Department of Molecular and Cell Biology, University of Cape Town, Cape Town, South Africa.,Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Rosamund Chapman
- Division of Medical Virology, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Ann E Meyers
- Biopharming Research Unit, Department of Molecular and Cell Biology, University of Cape Town, Cape Town, South Africa
| | - Emmanuel Margolin
- Division of Medical Virology, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Biopharming Research Unit, Department of Molecular and Cell Biology, University of Cape Town, Cape Town, South Africa.,Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Michiel T van Diepen
- Division of Medical Virology, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Anna-Lise Williamson
- Division of Medical Virology, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Edward P Rybicki
- Biopharming Research Unit, Department of Molecular and Cell Biology, University of Cape Town, Cape Town, South Africa.,Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| |
Collapse
|
7
|
Rantalainen K, Berndsen ZT, Murrell S, Cao L, Omorodion O, Torres JL, Wu M, Umotoy J, Copps J, Poignard P, Landais E, Paulson JC, Wilson IA, Ward AB. Co-evolution of HIV Envelope and Apex-Targeting Neutralizing Antibody Lineage Provides Benchmarks for Vaccine Design. Cell Rep 2019; 23:3249-3261. [PMID: 29898396 PMCID: PMC6019700 DOI: 10.1016/j.celrep.2018.05.046] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 04/09/2018] [Accepted: 05/14/2018] [Indexed: 11/28/2022] Open
Abstract
Broadly neutralizing antibodies (bnAbs) targeting the HIV envelope glycoprotein (Env) typically take years to develop. Longitudinal analyses of both neutralizing antibody lineages and viruses at serial time points during infection provide a basis for understanding the co-evolutionary contest between HIV and the humoral immune system. Here, we describe the structural characterization of an apex-targeting antibody lineage and autologous clade A viral Env from a donor in the Protocol C cohort. Comparison of Ab-Env complexes at early and late time points reveals that, within the antibody lineage, the CDRH3 loop rigidifies, the bnAb angle of approach steepens, and surface charges are mutated to accommodate glycan changes. Additionally, we observed differences in site-specific glycosylation between soluble and full-length Env constructs, which may be important for tuning optimal immunogenicity in soluble Env trimers. These studies therefore provide important guideposts for design of immunogens that prime and mature nAb responses to the Env V2-apex. HIV Env-antibody structural co-evolution in PC64 donor involves five key mechanisms Antibody binding angle, CDRH3 loop, surface charges, and glycan contacts are affected Membrane-bound recombinant Env glycan shield differs from the soluble, SOSIP Env
Collapse
Affiliation(s)
- Kimmo Rantalainen
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA; IAVI Neutralizing Antibody Center and Collaboration of AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Zachary T Berndsen
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA; IAVI Neutralizing Antibody Center and Collaboration of AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Sasha Murrell
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA; IAVI Neutralizing Antibody Center and Collaboration of AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Liwei Cao
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Oluwarotimi Omorodion
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA; IAVI Neutralizing Antibody Center and Collaboration of AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Jonathan L Torres
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Mengyu Wu
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Jeffrey Umotoy
- IAVI Neutralizing Antibody Center and Collaboration of AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Jeffrey Copps
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA; IAVI Neutralizing Antibody Center and Collaboration of AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Pascal Poignard
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037, USA; IAVI Neutralizing Antibody Center and Collaboration of AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Elise Landais
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037, USA; IAVI Neutralizing Antibody Center and Collaboration of AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - James C Paulson
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Ian A Wilson
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA; IAVI Neutralizing Antibody Center and Collaboration of AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Andrew B Ward
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA; IAVI Neutralizing Antibody Center and Collaboration of AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, CA 92037, USA.
| |
Collapse
|
8
|
Seabright GE, Doores KJ, Burton DR, Crispin M. Protein and Glycan Mimicry in HIV Vaccine Design. J Mol Biol 2019; 431:2223-2247. [PMID: 31028779 PMCID: PMC6556556 DOI: 10.1016/j.jmb.2019.04.016] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 04/12/2019] [Accepted: 04/13/2019] [Indexed: 01/30/2023]
Abstract
Antigenic mimicry is a fundamental tenet of structure-based vaccinology. Vaccine strategies for the human immunodeficiency virus type 1 (HIV-1) focus on the mimicry of its envelope spike (Env) due to its exposed location on the viral membrane and role in mediating infection. However, the virus has evolved to minimize the immunogenicity of conserved epitopes on the envelope spike. This principle is starkly illustrated by the presence of an extensive array of host-derived glycans, which act to shield the underlying protein from antibody recognition. Despite these hurdles, a subset of HIV-infected individuals eventually develop broadly neutralizing antibodies that recognize these virally presented glycans. Effective HIV-1 immunogens are therefore likely to involve some degree of mimicry of both the protein and glycan components of Env. As such, considerable efforts have been made to characterize the structure of the envelope spike and its glycan shield. This review summarizes the recent progress made in this field, with an emphasis on our growing understanding of the factors shaping the glycan shield of Env derived from both virus and soluble immunogens. We argue that recombinant mimics of the envelope spike are currently capable of capturing many features of the native viral glycan shield. Finally, we explore strategies through which the immunogenicity of Env glycans may be enhanced in the development of future immunogens.
Collapse
Affiliation(s)
- Gemma E Seabright
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK; School of Biological Sciences, University of Southampton, Southampton, SO17 1BJ, UK
| | - Katie J Doores
- Department of Infectious Diseases, King's College London, Guy's Hospital, London, SE1 9RT, UK
| | - Dennis R Burton
- Department of Immunology and Microbiology, the Scripps Centre for HIV/AIDS Vaccine Immunology and Immunogen Discovery (CHAVI-ID), International AIDS Vaccine Initiative Neutralizing Antibody Centre, Scripps Research, La Jolla, CA 92037, USA
| | - Max Crispin
- School of Biological Sciences, University of Southampton, Southampton, SO17 1BJ, UK; Department of Immunology and Microbiology, the Scripps Centre for HIV/AIDS Vaccine Immunology and Immunogen Discovery (CHAVI-ID), International AIDS Vaccine Initiative Neutralizing Antibody Centre, Scripps Research, La Jolla, CA 92037, USA.
| |
Collapse
|
9
|
Conformational Engineering of HIV-1 Env Based on Mutational Tolerance in the CD4 and PG16 Bound States. J Virol 2019; 93:JVI.00219-19. [PMID: 30894475 DOI: 10.1128/jvi.00219-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 03/16/2019] [Indexed: 12/22/2022] Open
Abstract
HIV-1 infection is initiated by viral Env engaging the host receptor CD4, triggering Env to transition from a "closed" to "open" conformation during the early events of virus-cell membrane fusion. To understand how Env sequence accommodates this conformational change, mutational landscapes decoupled from virus replication were determined for Env from BaL (clade B) and DU422 (clade C) isolates interacting with CD4 or antibody PG16 that preferentially recognizes closed trimers. Sequence features uniquely important to each bound state were identified, including glycosylation and binding sites. Notably, the Env apical domain and trimerization interface are under selective pressure for PG16 binding. Based on this key observation, mutations were found that increase presentation of quaternary epitopes associated with properly conformed trimers when Env is expressed at the plasma membrane. Many mutations reduce electrostatic repulsion at the Env apex and increase PG16 recognition of Env sequences from clades A and B. Other mutations increase hydrophobic packing at the gp120 inner-outer domain interface and were broadly applicable for engineering Env from diverse strains spanning tiers 1, 2, and 3 across clades A, B, C, and BC recombinants. Core mutations predicted to introduce steric strain in the open state show markedly reduced CD4 interactions. Finally, we demonstrate how our methodology can be adapted to interrogate interactions between membrane-associated Env and the matrix domain of Gag. These findings and methods may assist vaccine design.IMPORTANCE HIV-1 Env is dynamic and undergoes large conformational changes that drive fusion of virus and host cell membranes. Three Env proteins in a trimer contact each other at their apical tips to form a closed conformation that presents epitopes recognized by broadly neutralizing antibodies. The apical tips separate, among other changes, to form an open conformation that binds tightly to host receptors. Understanding how Env sequence facilitates these structural changes can inform the biophysical mechanism and aid immunogen design. Using deep mutational scans decoupled from virus replication, we report mutational landscapes for Env from two strains interacting with conformation-dependent binding proteins. Residues in the Env trimer interface and apical domains are preferentially conserved in the closed conformation, and conformational diversity is facilitated by electrostatic repulsion and an underpacked core between domains. Specific mutations are described that enhance presentation of the trimeric closed conformation across diverse HIV-1 strains.
Collapse
|
10
|
Magaret CA, Benkeser DC, Williamson BD, Borate BR, Carpp LN, Georgiev IS, Setliff I, Dingens AS, Simon N, Carone M, Simpkins C, Montefiori D, Alter G, Yu WH, Juraska M, Edlefsen PT, Karuna S, Mgodi NM, Edugupanti S, Gilbert PB. Prediction of VRC01 neutralization sensitivity by HIV-1 gp160 sequence features. PLoS Comput Biol 2019; 15:e1006952. [PMID: 30933973 PMCID: PMC6459550 DOI: 10.1371/journal.pcbi.1006952] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 04/11/2019] [Accepted: 03/14/2019] [Indexed: 11/29/2022] Open
Abstract
The broadly neutralizing antibody (bnAb) VRC01 is being evaluated for its efficacy to prevent HIV-1 infection in the Antibody Mediated Prevention (AMP) trials. A secondary objective of AMP utilizes sieve analysis to investigate how VRC01 prevention efficacy (PE) varies with HIV-1 envelope (Env) amino acid (AA) sequence features. An exhaustive analysis that tests how PE depends on every AA feature with sufficient variation would have low statistical power. To design an adequately powered primary sieve analysis for AMP, we modeled VRC01 neutralization as a function of Env AA sequence features of 611 HIV-1 gp160 pseudoviruses from the CATNAP database, with objectives: (1) to develop models that best predict the neutralization readouts; and (2) to rank AA features by their predictive importance with classification and regression methods. The dataset was split in half, and machine learning algorithms were applied to each half, each analyzed separately using cross-validation and hold-out validation. We selected Super Learner, a nonparametric ensemble-based cross-validated learning method, for advancement to the primary sieve analysis. This method predicted the dichotomous resistance outcome of whether the IC50 neutralization titer of VRC01 for a given Env pseudovirus is right-censored (indicating resistance) with an average validated AUC of 0.868 across the two hold-out datasets. Quantitative log IC50 was predicted with an average validated R2 of 0.355. Features predicting neutralization sensitivity or resistance included 26 surface-accessible residues in the VRC01 and CD4 binding footprints, the length of gp120, the length of Env, the number of cysteines in gp120, the number of cysteines in Env, and 4 potential N-linked glycosylation sites; the top features will be advanced to the primary sieve analysis. This modeling framework may also inform the study of VRC01 in the treatment of HIV-infected persons.
Collapse
Affiliation(s)
- Craig A. Magaret
- Vaccine and Infectious Disease Division and Statistical Center for HIV/AIDS Research and Prevention, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - David C. Benkeser
- Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, Georgia, United States of America
| | - Brian D. Williamson
- Department of Biostatistics, University of Washington, Seattle, Washington, United States of America
| | - Bhavesh R. Borate
- Vaccine and Infectious Disease Division and Statistical Center for HIV/AIDS Research and Prevention, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Lindsay N. Carpp
- Vaccine and Infectious Disease Division and Statistical Center for HIV/AIDS Research and Prevention, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Ivelin S. Georgiev
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Ian Setliff
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Program in Chemical & Physical Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Adam S. Dingens
- Division of Basic Sciences and Computational Biology Program, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- Division of Human Biology and Epidemiology Program, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- Molecular and Cellular Biology PhD Program, University of Washington, Seattle, Washington, United States of America
| | - Noah Simon
- Department of Biostatistics, University of Washington, Seattle, Washington, United States of America
| | - Marco Carone
- Department of Biostatistics, University of Washington, Seattle, Washington, United States of America
| | - Christopher Simpkins
- Vaccine and Infectious Disease Division and Statistical Center for HIV/AIDS Research and Prevention, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - David Montefiori
- Duke University School of Medicine, Duke University, Durham, North Carolina, United States of America
| | - Galit Alter
- Ragon Institute of MGH, MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Wen-Han Yu
- Ragon Institute of MGH, MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Michal Juraska
- Vaccine and Infectious Disease Division and Statistical Center for HIV/AIDS Research and Prevention, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Paul T. Edlefsen
- Vaccine and Infectious Disease Division and Statistical Center for HIV/AIDS Research and Prevention, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Shelly Karuna
- Vaccine and Infectious Disease Division and Statistical Center for HIV/AIDS Research and Prevention, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Nyaradzo M. Mgodi
- University of Zimbabwe College of Health Sciences Clinical Trials Research Centre, Harare, Zimbabwe
| | - Srilatha Edugupanti
- Department of Medicine, Division of Infectious Diseases, Emory University, Atlanta, Georgia, United States of America
| | - Peter B. Gilbert
- Vaccine and Infectious Disease Division and Statistical Center for HIV/AIDS Research and Prevention, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- Department of Biostatistics, University of Washington, Seattle, Washington, United States of America
| |
Collapse
|
11
|
de Taeye SW, Go EP, Sliepen K, de la Peña AT, Badal K, Medina-Ramírez M, Lee WH, Desaire H, Wilson IA, Moore JP, Ward AB, Sanders RW. Stabilization of the V2 loop improves the presentation of V2 loop-associated broadly neutralizing antibody epitopes on HIV-1 envelope trimers. J Biol Chem 2019; 294:5616-5631. [PMID: 30728245 PMCID: PMC6462529 DOI: 10.1074/jbc.ra118.005396] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 01/15/2019] [Indexed: 11/16/2022] Open
Abstract
A successful HIV-1 vaccine will likely need to elicit broadly neutralizing antibodies (bNAbs) that target the envelope glycoprotein (Env) spike on the virus. Native-like recombinant Env trimers of the SOSIP design now serve as a platform for achieving this challenging goal. However, SOSIP trimers usually do not bind efficiently to the inferred germline precursors of bNAbs (gl-bNAbs). We hypothesized that the inherent flexibilities of the V1 and V2 variable loops in the Env trimer contribute to the poor recognition of gl-bNAb epitopes at the trimer apex that extensively involve V2 residues. To reduce local V2 flexibility and improve the binding of V2-dependent bNAbs and gl-bNAbs, we designed BG505 SOSIP.664 trimer variants containing newly created disulfide bonds intended to stabilize the V2 loop in an optimally antigenic configuration. The first variant, I184C/E190C, contained a new disulfide bond within the V2 loop, whereas the second variant, E153C/R178C, had a new disulfide bond that cross-linked V2 and V1. The resulting engineered native-like trimer variants were both more reactive with and were neutralized by V2 bNAbs and gl-bNAbs, a finding that may be valuable in the design of germline targeting and boosting trimer immunogens to create an antigenic conformation optimal for HIV vaccine development.
Collapse
Affiliation(s)
- Steven W de Taeye
- From the Department of Medical Microbiology, Amsterdam UMC, University of Amsterdam, Amsterdam, 1105 AZ, The Netherlands
| | - Eden P Go
- the Department of Chemistry, University of Kansas, Lawrence, Kansas 66045
| | - Kwinten Sliepen
- From the Department of Medical Microbiology, Amsterdam UMC, University of Amsterdam, Amsterdam, 1105 AZ, The Netherlands
| | - Alba Torrents de la Peña
- From the Department of Medical Microbiology, Amsterdam UMC, University of Amsterdam, Amsterdam, 1105 AZ, The Netherlands
| | - Kimberly Badal
- From the Department of Medical Microbiology, Amsterdam UMC, University of Amsterdam, Amsterdam, 1105 AZ, The Netherlands
| | - Max Medina-Ramírez
- From the Department of Medical Microbiology, Amsterdam UMC, University of Amsterdam, Amsterdam, 1105 AZ, The Netherlands
| | - Wen-Hsin Lee
- the Department of Integrative Structural and Computational Biology, Scripps CHAVI-ID, IAVI Neutralizing Antibody Center and Collaboration for AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, California 92037, and
| | - Heather Desaire
- the Department of Chemistry, University of Kansas, Lawrence, Kansas 66045
| | - Ian A Wilson
- the Department of Integrative Structural and Computational Biology, Scripps CHAVI-ID, IAVI Neutralizing Antibody Center and Collaboration for AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, California 92037, and
| | - John P Moore
- the Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York 10021
| | - Andrew B Ward
- the Department of Integrative Structural and Computational Biology, Scripps CHAVI-ID, IAVI Neutralizing Antibody Center and Collaboration for AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, California 92037, and
| | - Rogier W Sanders
- From the Department of Medical Microbiology, Amsterdam UMC, University of Amsterdam, Amsterdam, 1105 AZ, The Netherlands, .,the Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York 10021
| |
Collapse
|
12
|
Park DD, Xu G, Wong M, Phoomak C, Liu M, Haigh NE, Wongkham S, Yang P, Maverakis E, Lebrilla CB. Membrane glycomics reveal heterogeneity and quantitative distribution of cell surface sialylation. Chem Sci 2018; 9:6271-6285. [PMID: 30123482 PMCID: PMC6063140 DOI: 10.1039/c8sc01875h] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 06/26/2018] [Indexed: 12/13/2022] Open
Abstract
Sialic acid distribution was quantified by LC-MS/MS. The number of sialylated glycoforms increases at sites nearest to the transmembrane domain.
Given that unnatural sugar expression is metabolically achieved, the kinetics and disposition of incorporation can lend insight into the temporal and localization preferences of sialylation across the cell surface. However, common detection schemes lack the ability to detail the molecular diversity and distribution of target moieties. Here we employed a mass spectrometric approach to trace the placement of azido sialic acids on membrane glycoconjugates, which revealed substantial variations in incorporation efficiencies between N-/O-glycans, glycosites, and glycosphingolipids. To further explore the propensity for sialylation, we subsequently mapped the native glycome of model epithelial cell surfaces and illustrate that while glycosylation sites span broadly across the extracellular region, a higher number of heterogeneous glycoforms occur on sialylated sites closest to the transmembrane domain. Beyond imaging techniques, this integrative approach provides unprecedented details about the frequency and structure-specific distribution of cell surface sialylation, a critical feature that regulates cellular interactions and homeostatic pathways.
Collapse
Affiliation(s)
- Diane Dayoung Park
- Department of Chemistry , University of California , Davis , CA 95616 , USA.,Department of Surgery , Beth Israel Deaconess Medical Center , Harvard Medical School , Boston , MA 02115 , USA .
| | - Gege Xu
- Department of Chemistry , University of California , Davis , CA 95616 , USA
| | - Maurice Wong
- Department of Chemistry , University of California , Davis , CA 95616 , USA
| | - Chatchai Phoomak
- Department of Biochemistry , Faculty of Medicine , Khon Kaen University , Khon Kaen 40002 , Thailand
| | - Mingqi Liu
- Department of Chemistry , Institutes of Biomedical Sciences , Fudan University , Shanghai 200032 , China
| | - Nathan E Haigh
- Department of Dermatology , University of California , Davis School of Medicine , Sacramento , CA 95817 , USA
| | - Sopit Wongkham
- Department of Biochemistry , Faculty of Medicine , Khon Kaen University , Khon Kaen 40002 , Thailand
| | - Pengyuan Yang
- Department of Chemistry , Institutes of Biomedical Sciences , Fudan University , Shanghai 200032 , China
| | - Emanual Maverakis
- Department of Dermatology , University of California , Davis School of Medicine , Sacramento , CA 95817 , USA
| | - Carlito B Lebrilla
- Department of Chemistry , University of California , Davis , CA 95616 , USA
| |
Collapse
|
13
|
Harnessing post-translational modifications for next-generation HIV immunogens. Biochem Soc Trans 2018; 46:691-698. [PMID: 29784645 DOI: 10.1042/bst20170394] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 04/10/2018] [Accepted: 04/17/2018] [Indexed: 12/12/2022]
Abstract
The extensive post-translational modifications of the envelope spikes of the human immunodeficiency virus (HIV) present considerable challenges and opportunities for HIV vaccine design. These oligomeric glycoproteins typically have over 30 disulfide bonds and around a 100 N-linked glycosylation sites, and are functionally dependent on protease cleavage within the secretory system. The resulting mature structure adopts a compact fold with the vast majority of its surface obscured by a protective shield of glycans which can be targeted by broadly neutralizing antibodies (bnAbs). Despite the notorious heterogeneity of glycosylation, rare B-cell lineages can evolve to utilize and cope with viral glycan diversity, and these structures therefore present promising targets for vaccine design. The latest generation of recombinant envelope spike mimetics contains re-engineered post-translational modifications to present stable antigens to guide the development of bnAbs by vaccination.
Collapse
|
14
|
Wagh K, Seaman MS, Zingg M, Fitzsimons T, Barouch DH, Burton DR, Connors M, Ho DD, Mascola JR, Nussenzweig MC, Ravetch J, Gautam R, Martin MA, Montefiori DC, Korber B. Potential of conventional & bispecific broadly neutralizing antibodies for prevention of HIV-1 subtype A, C & D infections. PLoS Pathog 2018; 14:e1006860. [PMID: 29505593 PMCID: PMC5854441 DOI: 10.1371/journal.ppat.1006860] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 03/15/2018] [Accepted: 01/08/2018] [Indexed: 12/18/2022] Open
Abstract
There is great interest in passive transfer of broadly neutralizing antibodies (bnAbs) and engineered bispecific antibodies (Abs) for prevention of HIV-1 infections due to their in vitro neutralization breadth and potency against global isolates and long in vivo half-lives. We compared the potential of eight bnAbs and two bispecific Abs currently under clinical development, and their 2 Ab combinations, to prevent infection by dominant HIV-1 subtypes in sub-Saharan Africa. Using in vitro neutralization data for Abs against 25 subtype A, 100 C, and 20 D pseudoviruses, we modeled neutralization by single Abs and 2 Ab combinations assuming realistic target concentrations of 10μg/ml total for bnAbs and combinations, and 5μg/ml for bispecifics. We used IC80 breadth-potency, completeness of neutralization, and simultaneous coverage by both Abs in the combination as metrics to characterize prevention potential. Additionally, we predicted in vivo protection by Abs and combinations by modeling protection as a function of in vitro neutralization based on data from a macaque simian-human immunodeficiency virus (SHIV) challenge study. Our model suggests that nearly complete neutralization of a given virus is needed for in vivo protection (~98% neutralization for 50% relative protection). Using the above metrics, we found that bnAb combinations should outperform single bnAbs, as expected; however, different combinations are optimal for different subtypes. Remarkably, a single bispecific 10E8-iMAb, which targets HIV Env and host-cell CD4, outperformed all combinations of two conventional bnAbs, with 95-97% predicted relative protection across subtypes. Combinations that included 10E8-iMAb substantially improved protection over use of 10E8-iMAb alone. Our results highlight the promise of 10E8-iMAb and its combinations to prevent HIV-1 infections in sub-Saharan Africa.
Collapse
Affiliation(s)
- Kshitij Wagh
- Theoretical Biology & Biophysics, Los Alamos National Laboratory, Los Alamos, United States of America
- New Mexico Consortium, Los Alamos, United States of America
- * E-mail: (BK); (KW)
| | - Michael S. Seaman
- Center for Virology & Vaccine Research, Beth Israel Deaconness Medical Center, Boston, United States of America
| | - Marshall Zingg
- Center for Virology & Vaccine Research, Beth Israel Deaconness Medical Center, Boston, United States of America
| | - Tomas Fitzsimons
- Center for Virology & Vaccine Research, Beth Israel Deaconness Medical Center, Boston, United States of America
| | - Dan H. Barouch
- Center for Virology & Vaccine Research, Beth Israel Deaconness Medical Center, Boston, United States of America
| | - Dennis R. Burton
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, United States of America
| | - Mark Connors
- Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda,United States of America
| | - David D. Ho
- Aaron Diamond AIDS Research Center, The Rockefeller University, New York, United States of America
| | - John R. Mascola
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Insitutes of Health, Bethesda, United States of America
| | - Michel C. Nussenzweig
- Laboratory of Molecular Immunology, The Rockefeller University, New York, United States of America
| | - Jeffrey Ravetch
- Laboratory of Molecular Genetics and Immunology, The Rockefeller University, New York, United States of America
| | - Rajeev Gautam
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, United States of America
| | - Malcolm A. Martin
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, United States of America
| | - David C. Montefiori
- Department of Surgery, Duke University Medical Center, Durham, United States of America
| | - Bette Korber
- Theoretical Biology & Biophysics, Los Alamos National Laboratory, Los Alamos, United States of America
- New Mexico Consortium, Los Alamos, United States of America
- * E-mail: (BK); (KW)
| |
Collapse
|
15
|
Behrens AJ, Kumar A, Medina-Ramirez M, Cupo A, Marshall K, Cruz Portillo VM, Harvey DJ, Ozorowski G, Zitzmann N, Wilson IA, Ward AB, Struwe WB, Moore JP, Sanders RW, Crispin M. Integrity of Glycosylation Processing of a Glycan-Depleted Trimeric HIV-1 Immunogen Targeting Key B-Cell Lineages. J Proteome Res 2018; 17:987-999. [PMID: 29420040 DOI: 10.1021/acs.jproteome.7b00639] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Broadly neutralizing antibodies (bNAbs) that target the trimeric HIV-1 envelope glycoprotein spike (Env) are tools that can guide the design of recombinant Env proteins intended to engage the predicted human germline precursors of bNAbs (gl-bNAbs). The protein components of gl-bNAb epitopes are often masked by glycans, while mature bNAbs can evolve to accommodate or bypass these shielding glycans. The design of germline-targeting Env immunogens therefore includes the targeted deletion of specific glycan sites. However, the processing of glycans on Env trimers can be influenced by the density with which they are packed together, a highly relevant point given the essential contributions under-processed glycans make to multiple bNAb epitopes. We sought to determine the impact of the removal of 15 potential N-glycan sites (5 per protomer) from the germline-targeting soluble trimer, BG505 SOSIP.v4.1-GT1, using quantitative, site-specific N-glycan mass spectrometry analysis. We find that, compared with SOSIP.664, there was little overall change in the glycan profile but only subtle increases in the extent of processing at sites immediately adjacent to where glycans had been deleted. We conclude that multiple glycans can be deleted from BG505 SOSIP trimers without perturbing the overall integrity of the glycan shield.
Collapse
Affiliation(s)
- Anna-Janina Behrens
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford , South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Abhinav Kumar
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford , South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Max Medina-Ramirez
- Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center of the University of Amsterdam , 1105 AZ Amsterdam, The Netherlands
| | - Albert Cupo
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York , New York, New York 10021, United States
| | - Kevin Marshall
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York , New York, New York 10021, United States
| | - Victor M Cruz Portillo
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York , New York, New York 10021, United States
| | - David J Harvey
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford , South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Gabriel Ozorowski
- Department of Integrative Structural and Computational Biology, IAVI Neutralizing Antibody Center and CAVD, Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, The Scripps Research Institute , La Jolla, California 92037, United States
| | - Nicole Zitzmann
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford , South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Ian A Wilson
- Department of Integrative Structural and Computational Biology, IAVI Neutralizing Antibody Center and CAVD, Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, The Scripps Research Institute , La Jolla, California 92037, United States.,Skaggs Institute for Chemical Biology, The Scripps Research Institute , La Jolla, California 92037, United States
| | - Andrew B Ward
- Department of Integrative Structural and Computational Biology, IAVI Neutralizing Antibody Center and CAVD, Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, The Scripps Research Institute , La Jolla, California 92037, United States
| | - Weston B Struwe
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford , South Parks Road, Oxford OX1 3QU, United Kingdom
| | - John P Moore
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York , New York, New York 10021, United States
| | - Rogier W Sanders
- Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center of the University of Amsterdam , 1105 AZ Amsterdam, The Netherlands.,Department of Microbiology and Immunology, Weill Cornell Medical College, New York , New York, New York 10021, United States
| | - Max Crispin
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford , South Parks Road, Oxford OX1 3QU, United Kingdom.,Centre for Biological Sciences and Institute for Life Sciences, University of Southampton , Southampton SO17 1BJ, United Kingdom
| |
Collapse
|
16
|
Lakbub JC, Shipman JT, Desaire H. Recent mass spectrometry-based techniques and considerations for disulfide bond characterization in proteins. Anal Bioanal Chem 2017; 410:2467-2484. [PMID: 29256076 DOI: 10.1007/s00216-017-0772-1] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 11/09/2017] [Accepted: 11/17/2017] [Indexed: 12/21/2022]
Abstract
Disulfide bonds are important structural moieties of proteins: they ensure proper folding, provide stability, and ensure proper function. With the increasing use of proteins for biotherapeutics, particularly monoclonal antibodies, which are highly disulfide bonded, it is now important to confirm the correct disulfide bond connectivity and to verify the presence, or absence, of disulfide bond variants in the protein therapeutics. These studies help to ensure safety and efficacy. Hence, disulfide bonds are among the critical quality attributes of proteins that have to be monitored closely during the development of biotherapeutics. However, disulfide bond analysis is challenging because of the complexity of the biomolecules. Mass spectrometry (MS) has been the go-to analytical tool for the characterization of such complex biomolecules, and several methods have been reported to meet the challenging task of mapping disulfide bonds in proteins. In this review, we describe the relevant, recent MS-based techniques and provide important considerations needed for efficient disulfide bond analysis in proteins. The review focuses on methods for proper sample preparation, fragmentation techniques for disulfide bond analysis, recent disulfide bond mapping methods based on the fragmentation techniques, and automated algorithms designed for rapid analysis of disulfide bonds from liquid chromatography-MS/MS data. Researchers involved in method development for protein characterization can use the information herein to facilitate development of new MS-based methods for protein disulfide bond analysis. In addition, individuals characterizing biotherapeutics, especially by disulfide bond mapping in antibodies, can use this review to choose the best strategies for disulfide bond assignment of their biologic products. Graphical Abstract This review, describing characterization methods for disulfide bonds in proteins, focuses on three critical components: sample preparation, mass spectrometry data, and software tools.
Collapse
Affiliation(s)
- Jude C Lakbub
- Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, 1251 Wescoe Hall Dr, Lawrence, KS, 66045, USA
| | - Joshua T Shipman
- Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, 1251 Wescoe Hall Dr, Lawrence, KS, 66045, USA
| | - Heather Desaire
- Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, 1251 Wescoe Hall Dr, Lawrence, KS, 66045, USA.
| |
Collapse
|
17
|
Dey AK, Cupo A, Ozorowski G, Sharma VK, Behrens AJ, Go EP, Ketas TJ, Yasmeen A, Klasse PJ, Sayeed E, Desaire H, Crispin M, Wilson IA, Sanders RW, Hassell T, Ward AB, Moore JP. cGMP production and analysis of BG505 SOSIP.664, an extensively glycosylated, trimeric HIV-1 envelope glycoprotein vaccine candidate. Biotechnol Bioeng 2017; 115:885-899. [PMID: 29150937 PMCID: PMC5852640 DOI: 10.1002/bit.26498] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 10/30/2017] [Accepted: 11/14/2017] [Indexed: 12/30/2022]
Abstract
We describe the properties of BG505 SOSIP.664 HIV‐1 envelope glycoprotein trimers produced under current Good Manufacturing Practice (cGMP) conditions. These proteins are the first of a new generation of native‐like trimers that are the basis for many structure‐guided immunogen development programs aimed at devising how to induce broadly neutralizing antibodies (bNAbs) to HIV‐1 by vaccination. The successful translation of this prototype demonstrates the feasibility of producing similar immunogens on an appropriate scale and of an acceptable quality for Phase I experimental medicine clinical trials. BG505 SOSIP.664 trimers are extensively glycosylated, contain numerous disulfide bonds and require proteolytic cleavage, all properties that pose a substantial challenge to cGMP production. Our strategy involved creating a stable CHO cell line that was adapted to serum‐free culture conditions to produce envelope glycoproteins. The trimers were then purified by chromatographic methods using a 2G12 bNAb affinity column and size‐exclusion chromatography. The chosen procedures allowed any adventitious viruses to be cleared from the final product to the required extent of >12 log10. The final cGMP production run yielded 3.52 g (peptidic mass) of fully purified trimers (Drug Substance) from a 200 L bioreactor, a notable yield for such a complex glycoprotein. The purified trimers were fully native‐like as judged by negative‐stain electron microscopy, and were stable over a multi‐month period at room temperature or below and for at least 1 week at 50°C. Their antigenicity, disulfide bond patterns, and glycan composition were consistent with trimers produced on a research laboratory scale. The methods reported here should pave the way for the cGMP production of other native‐like Env glycoprotein trimers of various designs and genotypes.
Collapse
Affiliation(s)
- Antu K Dey
- International AIDS Vaccine Initiative, New York, New York
| | - Albert Cupo
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York
| | - Gabriel Ozorowski
- Department of Integrative Structural and Computational Biology, International AIDS Vaccine Initiative (IAVI) Neutralizing Antibody Center and the Collaboration for AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, California
| | | | - Anna-Janina Behrens
- Department of Biochemistry, Oxford Glycobiology Institute, University of Oxford, Oxford, UK.,Centre for Biological Sciences and Institute for Life Sciences, University of Southampton, Southampton, UK
| | - Eden P Go
- Department of Chemistry, The University of Kansas, Lawrence, Kansas
| | - Thomas J Ketas
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York
| | - Anila Yasmeen
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York
| | - Per J Klasse
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York
| | - Eddy Sayeed
- International AIDS Vaccine Initiative, New York, New York
| | - Heather Desaire
- Department of Chemistry, The University of Kansas, Lawrence, Kansas
| | - Max Crispin
- Department of Biochemistry, Oxford Glycobiology Institute, University of Oxford, Oxford, UK
| | - Ian A Wilson
- Department of Integrative Structural and Computational Biology, International AIDS Vaccine Initiative (IAVI) Neutralizing Antibody Center and the Collaboration for AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, California
| | - Rogier W Sanders
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York.,Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Thomas Hassell
- International AIDS Vaccine Initiative, New York, New York
| | - Andrew B Ward
- Department of Integrative Structural and Computational Biology, International AIDS Vaccine Initiative (IAVI) Neutralizing Antibody Center and the Collaboration for AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, California
| | - John P Moore
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York
| |
Collapse
|
18
|
Abstract
Structure determination of the HIV-1 envelope glycoprotein (Env) presented a number of challenges, but several high-resolution structures have now become available. In 2013, cryo-EM and x-ray structures of soluble, cleaved SOSIP Env trimers from the clade A BG505 strain provided the first glimpses into the Env trimer fold as well as more the variable regions. A recent cryo-EM structure of a native full-length trimer without any stabilizing mutations had the same core structure, but revealed new insights and features. A more comprehensive and higher resolution understanding of the glycan shield has also emerged, enabling a more complete representation of the Env glycoprotein structure. Complexes of Env trimers with broadly neutralizing antibodies have surprisingly illustrated that most of the Env surface can be targeted in natural infection and that the neutralizing epitopes are almost all composed of both peptide and glycan components. These structures have also provided further evidence of the inherent plasticity of Env and how antibodies can exploit this flexibility by perturbing or even stabilizing the trimer to facilitate neutralization. These breakthroughs have stimulated further design and stabilization of Env trimers as well as other platforms to generate trimers that now span multiple subtypes. These Env trimers when used as immunogens, have led to the first vaccine-induced neutralizing antibodies for structural and functional analyses.
Collapse
Affiliation(s)
- Andrew B Ward
- Department of Integrative Structural and Computational Biology, International AIDS Vaccine Initiative Neutralizing Antibody Center, Collaboration for AIDS Vaccine Discovery, and Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, La Jolla, CA, USA
| | - Ian A Wilson
- Department of Integrative Structural and Computational Biology, International AIDS Vaccine Initiative Neutralizing Antibody Center, Collaboration for AIDS Vaccine Discovery, and Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, La Jolla, CA, USA.,Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA, USA
| |
Collapse
|
19
|
Glycosylation Benchmark Profile for HIV-1 Envelope Glycoprotein Production Based on Eleven Env Trimers. J Virol 2017; 91:JVI.02428-16. [PMID: 28202756 DOI: 10.1128/jvi.02428-16] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 02/02/2017] [Indexed: 02/02/2023] Open
Abstract
HIV-1 envelope glycoprotein (Env) glycosylation is important because individual glycans are components of multiple broadly neutralizing antibody epitopes, while shielding other sites that might otherwise be immunogenic. The glycosylation on Env is influenced by a variety of factors, including the genotype of the protein, the cell line used for its expression, and the details of the construct design. Here, we used a mass spectrometry (MS)-based approach to map the complete glycosylation profile at every site in multiple HIV-1 Env trimers, accomplishing two goals. (i) We determined which glycosylation sites contain conserved glycan profiles across many trimeric Envs. (ii) We identified the variables that impact Env's glycosylation profile at sites with divergent glycosylation. Over half of the gp120 glycosylation sites on 11 different trimeric Envs have a conserved glycan profile, indicating that a native consensus glycosylation profile does indeed exist among trimers. We showed that some soluble gp120s and gp140s exhibit highly divergent glycosylation profiles compared to trimeric Env. We also assessed the impact of several variables on Env glycosylation: truncating the full-length Env; producing Env, instead of the more virologically relevant T lymphocytes, in CHO cells; and purifying Env with different chromatographic platforms, including nickel-nitrilotriacetic acid (Ni-NTA), 2G12, and PGT151 affinity. This report provides the first consensus glycosylation profile of Env trimers, which should serve as a useful benchmark for HIV-1 vaccine developers. This report also defines the sites where glycosylation may be impacted when Env trimers are truncated or produced in CHO cells.IMPORTANCE A protective HIV-1 vaccine will likely include a recombinant version of the viral envelope glycoprotein (Env). Env is highly glycosylated, and yet vaccine developers have lacked guidance on how to assess whether their immunogens have optimal glycosylation. The following important questions are still unanswered. (i) What is the "target" glycosylation profile, when the goal is to generate a natively glycosylated protein? (ii) What variables exert the greatest influence on Env glycosylation? We identified numerous sites on Env where the glycosylation profile does not deviate in 11 different Env trimers, and we investigated the impact on the divergent glycosylation profiles of changing the genotype of the Env sequence, the construct design, the purification method, and the producer cell type. The data presented here give vaccine developers a "glycosylation target" for their immunogens, and they show how protein production variables can impact Env glycosylation.
Collapse
|
20
|
Molecular Architecture of the Cleavage-Dependent Mannose Patch on a Soluble HIV-1 Envelope Glycoprotein Trimer. J Virol 2017; 91:JVI.01894-16. [PMID: 27807235 DOI: 10.1128/jvi.01894-16] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 10/25/2016] [Indexed: 01/04/2023] Open
Abstract
The formation of a correctly folded and natively glycosylated HIV-1 viral spike is dependent on protease cleavage of the gp160 precursor protein in the Golgi apparatus. Cleavage induces a compact structure which not only renders the spike capable of fusion but also limits further maturation of its extensive glycosylation. The redirection of the glycosylation pathway to preserve underprocessed oligomannose-type glycans is an important feature in immunogen design, as glycans contribute to or influence the epitopes of numerous broadly neutralizing antibodies. Here we present a quantitative site-specific analysis of a recombinant, trimeric mimic of the native HIV-1 viral spike (BG505 SOSIP.664) compared to the corresponding uncleaved pseudotrimer and the matched gp120 monomer. We present a detailed molecular map of a trimer-associated glycan remodeling that forms a localized subdomain of the native mannose patch. The formation of native trimers is a critical design feature in shaping the glycan epitopes presented on recombinant vaccine candidates. IMPORTANCE The envelope spike of human immunodeficiency virus type 1 (HIV-1) is a target for antibody-based neutralization. For some patients infected with HIV-1, highly potent antibodies have been isolated that can neutralize a wide range of circulating viruses. It is a goal of HIV-1 vaccine research to elicit these antibodies by immunization with recombinant mimics of the viral spike. These antibodies have evolved to recognize the dense array of glycans that coat the surface of the viral molecule. We show how the structure of these glycans is shaped by steric constraints imposed upon them by the native folding of the viral spike. This information is important in guiding the development of vaccine candidates.
Collapse
|
21
|
Abstract
We describe the development and potential use of various designs of recombinant HIV-1 envelope glycoprotein trimers that mimic the structure of the virion-associated spike, which is the target for neutralizing antibodies. The goal of trimer development programs is to induce broadly neutralizing antibodies with the potential to intervene against multiple circulating HIV-1 strains. Among the topics we address are the designs of various constructs; how native-like trimers can be produced and purified; the properties of such trimers in vitro and their immunogenicity in various animals; and the immunization strategies that may lead to the eventual elicitation of broadly neutralizing antibodies. In summary, native-like trimers are a now a platform for structure- and immunology-based design improvements that could eventually yield immunogens of practical value for solving the long-standing HIV-1 vaccine problem.
Collapse
Affiliation(s)
- Rogier W. Sanders
- Department of Microbiology and ImmunologyWeill Medical College of Cornell UniversityNew YorkNYUSA
- Department of Medical MicrobiologyAcademic Medical CenterUniversity of AmsterdamAmsterdamThe Netherlands
| | - John P. Moore
- Department of Microbiology and ImmunologyWeill Medical College of Cornell UniversityNew YorkNYUSA
| |
Collapse
|
22
|
Lakbub JC, Clark DF, Shah IS, Zhu Z, Go EP, Tolbert TJ, Desaire H. Disulfide Bond Characterization of Endogenous IgG3 Monoclonal Antibodies Using LC-MS: An Investigation of IgG3 Disulfide-mediated Isoforms. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2016; 8:6046-6055. [PMID: 28989532 PMCID: PMC5629967 DOI: 10.1039/c6ay01248e] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The use of monoclonal antibodies (mAbs) for the manufacture of innovator and biosimilar biotherapeutics has increased tremendously in recent years. From a structural perspective, mAbs have high disulfide bond content, and the correct disulfide connectivity is required for proper folding and to maintain their biological activity. Therefore, disulfide linkage mapping is an important component of mAB characterization for ensuring drug safety and efficacy. The native disulfide linkage patterns of all four subclasses of IgG antibodies have been well established since the late 1960s. Among these IgG subtypes, disulfide mediated isoforms have been identified for IgG2 and IgG4, and to a lesser extent in IgG1, which is the most studied IgG subclass. However, no studies have been carried out so far to investigate whether different IgG3 isoforms exist due to alternative disulfide connectivity. In an effort to investigate the presence of disulfide-mediated isoforms in IgG3, we employed a bottom-up mass spectrometry approach to accurately determine the disulfide bond linkages in endogenous human IgG3 monoclonal antibody and our results show that no such alternative disulfide bonds exist. While many antibody-based drugs are developed around IgG1, IgG3 represents a new, and in some cases, more desirable drug candidate. Our data represent the first demonstration that alternative disulfide bond arrangements are not present in endogenous IgG3; and therefore, they should not be present in recombinant forms used as antibody-based therapeutics.
Collapse
Affiliation(s)
- Jude C. Lakbub
- Department of Chemistry, University of Kansas, Lawrence, KS, 66047
| | - Daniel F. Clark
- Department of Chemistry, University of Kansas, Lawrence, KS, 66047
| | - Ishan S. Shah
- Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS, 66047
| | - Zhikai Zhu
- Department of Chemistry, University of Kansas, Lawrence, KS, 66047
| | - Eden P. Go
- Department of Chemistry, University of Kansas, Lawrence, KS, 66047
| | - Thomas J. Tolbert
- Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS, 66047
| | - Heather Desaire
- Department of Chemistry, University of Kansas, Lawrence, KS, 66047
| |
Collapse
|
23
|
Range of CD4-Bound Conformations of HIV-1 gp120, as Defined Using Conditional CD4-Induced Antibodies. J Virol 2016; 90:4481-4493. [PMID: 26889042 DOI: 10.1128/jvi.03206-15] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 02/14/2016] [Indexed: 01/23/2023] Open
Abstract
UNLABELLED The HIV envelope binds cellular CD4 and undergoes a range of conformational changes that lead to membrane fusion and delivery of the viral nucleocapsid into the cellular cytoplasm. This binding to CD4 reveals cryptic and highly conserved epitopes, the molecular nature of which is still not fully understood. The atomic structures of CD4 complexed with gp120 core molecules (a form of gp120 in which the V1, V2, and V3 loops and N and C termini have been truncated) have indicated that a hallmark feature of the CD4-bound conformation is the bridging sheet minidomain. Variations in the orientation of the bridging sheet hairpins have been revealed when CD4-liganded gp120 was compared to CD4-unliganded trimeric envelope structures. Hence, there appears to be a number of conformational transitions possible in HIV-1 monomeric gp120 that are affected by CD4 binding. The spectrum of CD4-bound conformations has been interrogated in this study by using a well-characterized panel of conditional, CD4-induced (CD4i) monoclonal antibodies (MAbs) that bind HIV-1 gp120 and its mutations under various conditions. Two distinct CD4i epitopes of the outer domain were studied: the first comprises the bridging sheet, while the second contains elements of the V2 loop. Furthermore, we show that the unliganded extended monomeric core of gp120 (coree) assumes an intermediate CD4i conformation in solution that further undergoes detectable rearrangements upon association with CD4. These discoveries impact both accepted paradigms concerning gp120 structure and the field of HIV immunogen design. IMPORTANCE Elucidation of the conformational transitions that the HIV-1 envelope protein undergoes during the course of entry into CD4(+)cells is fundamental to our understanding of HIV biology. The binding of CD4 triggers a range of gp120 structural rearrangements that could present targets for future drug design and development of preventive vaccines. Here we have systematically interrogated and scrutinized these conformational transitions using a panel of antibody probes that share a specific preference for the CD4i conformations. These have been employed to study a collection of gp120 mutations and truncations. Through these analyses, we propose 4 distinct sequential steps in CD4i transitions of gp120 conformations, each defined by antibody specificities and structural requirements of the HIV envelope monomer. As a result, we not only provide new insights into this dynamic process but also define probes to further investigate HIV infection.
Collapse
|