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Viral and Host Factors Regulating HIV-1 Envelope Protein Trafficking and Particle Incorporation. Viruses 2022; 14:v14081729. [PMID: 36016351 PMCID: PMC9415270 DOI: 10.3390/v14081729] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/25/2022] [Accepted: 08/02/2022] [Indexed: 11/17/2022] Open
Abstract
The HIV-1 envelope glycoprotein (Env) is an essential structural component of the virus, serving as the receptor-binding protein and principal neutralizing determinant. Env trimers are incorporated into developing particles at the plasma membrane of infected cells. Incorporation of HIV-1 Env into particles in T cells and macrophages is regulated by the long Env cytoplasmic tail (CT) and the matrix region of Gag. The CT incorporates motifs that interact with cellular factors involved in endosomal trafficking. Env follows an unusual pathway to arrive at the site of particle assembly, first traversing the secretory pathway to the plasma membrane (PM), then undergoing endocytosis, followed by directed sorting to the site of particle assembly on the PM. Many aspects of Env trafficking remain to be defined, including the sequential events that occur following endocytosis, leading to productive recycling and particle incorporation. This review focuses on the host factors and pathways involved in Env trafficking, and discusses leading models of Env incorporation into particles.
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2
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Prévost J, Medjahed H, Vézina D, Chen HC, Hahn BH, Smith AB, Finzi A. HIV-1 Envelope Glycoproteins Proteolytic Cleavage Protects Infected Cells from ADCC Mediated by Plasma from Infected Individuals. Viruses 2021; 13:2236. [PMID: 34835042 PMCID: PMC8625184 DOI: 10.3390/v13112236] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 11/03/2021] [Accepted: 11/04/2021] [Indexed: 12/28/2022] Open
Abstract
The HIV-1 envelope glycoprotein (Env) is synthesized in the endoplasmic reticulum as a trimeric gp160 precursor, which requires proteolytic cleavage by a cellular furin protease to mediate virus-cell fusion. Env is conformationally flexible but controls its transition from the unbound "closed" conformation (State 1) to downstream CD4-bound conformations (States 2/3), which are required for fusion. In particular, HIV-1 has evolved several mechanisms that reduce the premature "opening" of Env which exposes highly conserved epitopes recognized by non-neutralizing antibodies (nnAbs) capable of mediating antibody-dependent cellular cytotoxicity (ADCC). Env cleavage decreases its conformational transitions favoring the adoption of the "closed" conformation. Here we altered the gp160 furin cleavage site to impair Env cleavage and to examine its impact on ADCC responses mediated by plasma from HIV-1-infected individuals. We found that infected primary CD4+ T cells expressing uncleaved, but not wildtype, Env are efficiently recognized by nnAbs and become highly susceptible to ADCC responses mediated by plasma from HIV-1-infected individuals. Thus, HIV-1 limits the exposure of uncleaved Env at the surface of HIV-1-infected cells at least in part to escape ADCC responses.
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Affiliation(s)
- Jérémie Prévost
- Centre de Recherche du CHUM, Montreal, QC H2X 0A9, Canada; (J.P.); (H.M.); (D.V.)
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, QC H2X 0A9, Canada
| | - Halima Medjahed
- Centre de Recherche du CHUM, Montreal, QC H2X 0A9, Canada; (J.P.); (H.M.); (D.V.)
| | - Dani Vézina
- Centre de Recherche du CHUM, Montreal, QC H2X 0A9, Canada; (J.P.); (H.M.); (D.V.)
| | - Hung-Ching Chen
- Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA 19104-6323, USA; (H.-C.C.); (A.B.S.III)
| | - Beatrice H. Hahn
- Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6076, USA;
| | - Amos B. Smith
- Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA 19104-6323, USA; (H.-C.C.); (A.B.S.III)
| | - Andrés Finzi
- Centre de Recherche du CHUM, Montreal, QC H2X 0A9, Canada; (J.P.); (H.M.); (D.V.)
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, QC H2X 0A9, Canada
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3
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Kumar R, Deshpande S, Sewall LM, Ozorowski G, Cottrell CA, Lee WH, Holden LG, Richey ST, Chandrawacar AS, Dhiman K, Ashish, Kumar V, Ahmed S, Hingankar N, Kumar N, Murugavel KG, Srikrishnan AK, Sok D, Ward AB, Bhattacharya J. Elicitation of potent serum neutralizing antibody responses in rabbits by immunization with an HIV-1 clade C trimeric Env derived from an Indian elite neutralizer. PLoS Pathog 2021; 17:e1008977. [PMID: 33826683 PMCID: PMC8055034 DOI: 10.1371/journal.ppat.1008977] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 04/19/2021] [Accepted: 03/02/2021] [Indexed: 01/06/2023] Open
Abstract
Evaluating the structure-function relationship of viral envelope (Env) evolution and the development of broadly cross-neutralizing antibodies (bnAbs) in natural infection can inform rational immunogen design. In the present study, we examined the magnitude and specificity of autologous neutralizing antibodies induced in rabbits by a novel HIV-1 clade C Env protein (1PGE-THIVC) vis-à-vis those developed in an elite neutralizer from whom the env sequence was obtained that was used to prepare the soluble Env protein. The novel 1PGE-THIVC Env trimer displayed a native like pre-fusion closed conformation in solution as determined by small angle X-ray scattering (SAXS) and negative stain electron microscopy (EM). This closed spike conformation of 1PGE-THIVC Env trimers was correlated with weak or undetectable binding of non-neutralizing monoclonal antibodies (mAbs) compared to neutralizing mAbs. Furthermore, 1PGE-THIVC SOSIP induced potent neutralizing antibodies in rabbits to autologous virus variants. The autologous neutralizing antibody specificity induced in rabbits by 1PGE-THIVC was mapped to the C3/V4 region (T362/P401) of viral Env. This observation agreed with electron microscopy polyclonal epitope mapping (EMPEM) of the Env trimer complexed with IgG Fab prepared from the immunized rabbit sera. Our study demonstrated neutralization of sequence matched and unmatched autologous viruses by serum antibodies induced in rabbits by 1PGE-THIVC and also highlighted a comparable specificity for the 1PGE-THIVC SOSIP trimer with that seen with polyclonal antibodies elicited in the elite neutralizer by negative-stain electron microscopy polyclonal epitope (ns-EMPEM) mapping.
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Affiliation(s)
- Rajesh Kumar
- Translational Health Science & Technology Institute, NCR Biotech Science Cluster, Faridabad, India
| | - Suprit Deshpande
- Translational Health Science & Technology Institute, NCR Biotech Science Cluster, Faridabad, India
| | - Leigh M. Sewall
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, United States of America
- Scripps Consortium for HIV/AIDS Vaccine Development (CHAVD), The Scripps Research Institute, La Jolla, California, United States of America
- IAVI Neutralizing Antibody Center and the Collaboration for AIDS Vaccine Discovery (CAVD), The Scripps Research Institute, La Jolla, California, United States of America
| | - Gabriel Ozorowski
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, United States of America
- Scripps Consortium for HIV/AIDS Vaccine Development (CHAVD), The Scripps Research Institute, La Jolla, California, United States of America
- IAVI Neutralizing Antibody Center and the Collaboration for AIDS Vaccine Discovery (CAVD), The Scripps Research Institute, La Jolla, California, United States of America
| | - Christopher A. Cottrell
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, United States of America
- Scripps Consortium for HIV/AIDS Vaccine Development (CHAVD), The Scripps Research Institute, La Jolla, California, United States of America
- IAVI Neutralizing Antibody Center and the Collaboration for AIDS Vaccine Discovery (CAVD), The Scripps Research Institute, La Jolla, California, United States of America
| | - Wen-Hsin Lee
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, United States of America
- Scripps Consortium for HIV/AIDS Vaccine Development (CHAVD), The Scripps Research Institute, La Jolla, California, United States of America
- IAVI Neutralizing Antibody Center and the Collaboration for AIDS Vaccine Discovery (CAVD), The Scripps Research Institute, La Jolla, California, United States of America
| | - Lauren G. Holden
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, United States of America
- Scripps Consortium for HIV/AIDS Vaccine Development (CHAVD), The Scripps Research Institute, La Jolla, California, United States of America
- IAVI Neutralizing Antibody Center and the Collaboration for AIDS Vaccine Discovery (CAVD), The Scripps Research Institute, La Jolla, California, United States of America
| | - Sara T. Richey
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, United States of America
- Scripps Consortium for HIV/AIDS Vaccine Development (CHAVD), The Scripps Research Institute, La Jolla, California, United States of America
- IAVI Neutralizing Antibody Center and the Collaboration for AIDS Vaccine Discovery (CAVD), The Scripps Research Institute, La Jolla, California, United States of America
| | - Antra Singh Chandrawacar
- CSIR-Institute of Microbial Technology (IMTECH), Chandigarh, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Kanika Dhiman
- CSIR-Institute of Microbial Technology (IMTECH), Chandigarh, India
| | - Ashish
- CSIR-Institute of Microbial Technology (IMTECH), Chandigarh, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Vivek Kumar
- Translational Health Science & Technology Institute, NCR Biotech Science Cluster, Faridabad, India
| | - Shubbir Ahmed
- Translational Health Science & Technology Institute, NCR Biotech Science Cluster, Faridabad, India
| | - Nitin Hingankar
- Translational Health Science & Technology Institute, NCR Biotech Science Cluster, Faridabad, India
| | - Naresh Kumar
- Translational Health Science & Technology Institute, NCR Biotech Science Cluster, Faridabad, India
| | - Kailapuri G. Murugavel
- Y. R. Gaitonde Centre for AIDS Research and Education, YRG CARE Laboratory, Rajiv Gandhi Salai, Adyar, Chennai, India
| | - Aylur K. Srikrishnan
- Y. R. Gaitonde Centre for AIDS Research and Education, YRG CARE Laboratory, Rajiv Gandhi Salai, Adyar, Chennai, India
| | - Devin Sok
- Scripps Consortium for HIV/AIDS Vaccine Development (CHAVD), The Scripps Research Institute, La Jolla, California, United States of America
- IAVI Neutralizing Antibody Center, The Scripps Research Institute, La Jolla, California, United States of America
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, California, United States of America
- International AIDS Vaccine Initiative (IAVI), New York, United States of America
| | - Andrew B. Ward
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, United States of America
- Scripps Consortium for HIV/AIDS Vaccine Development (CHAVD), The Scripps Research Institute, La Jolla, California, United States of America
- IAVI Neutralizing Antibody Center and the Collaboration for AIDS Vaccine Discovery (CAVD), The Scripps Research Institute, La Jolla, California, United States of America
| | - Jayanta Bhattacharya
- Translational Health Science & Technology Institute, NCR Biotech Science Cluster, Faridabad, India
- International AIDS Vaccine Initiative, New Delhi, India; International AIDS Vaccine Initiative, New York, New York, United States of America
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4
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Comparison of Uncleaved and Mature Human Immunodeficiency Virus Membrane Envelope Glycoprotein Trimers. J Virol 2018; 92:JVI.00277-18. [PMID: 29618643 DOI: 10.1128/jvi.00277-18] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 03/26/2018] [Indexed: 12/21/2022] Open
Abstract
The mature envelope glycoprotein (Env) spike on the surfaces of human immunodeficiency virus type 1 (HIV-1)-infected cells and virions is derived from proteolytic cleavage of a trimeric gp160 glycoprotein precursor. In these studies, we compared the conformations of cleaved and uncleaved membrane Envs with truncated cytoplasmic tails to those of stabilized soluble gp140 SOSIP.664 Env trimers. Deletion of the gp41 cytoplasmic tail did not significantly affect the sensitivity of viruses with the HIV-1AD8 Env to inhibition by antibodies or a CD4-mimetic compound. After glutaraldehyde fixation and purification from membranes, a cleaved Env exhibited a hydrodynamic radius of ∼10 nm and an antibody-binding profile largely consistent with that expected based on virus neutralization sensitivity. The purified cleaved Env trimers exhibited a hollow architecture with a central void near the trimer axis. Uncleaved Env, cross-linked and purified in parallel, exhibited a hydrodynamic radius similar to that of the cleaved Env. However, the uncleaved Env was recognized by poorly neutralizing antibodies and appeared by negative-stain electron microscopy to sample multiple conformations. Compared with membrane Envs, stabilized soluble gp140 SOSIP.664 Env trimers appear to be more compact, as reflected in their smaller hydrodynamic radii and negative-stain electron microscopy structures. The antigenic features of the soluble gp140 SOSIP.664 Env trimers differed from those of the cleaved membrane Env, particularly in gp120 V3 and some CD4-binding-site epitopes. Thus, proteolytic maturation allows the membrane-anchored Env to achieve a conformation that retains functional metastability but masks epitopes for poorly neutralizing antibodies.IMPORTANCE The entry of human immunodeficiency virus type 1 (HIV-1) into host cells is mediated by the envelope glycoprotein (Env) spike on the surface of the virus. Host antibodies elicited during natural HIV-1 infection or by vaccination can potentially recognize the Env spike and block HIV-1 infection. However, the changing shape of the HIV-1 Env spike protects the virus from antibody binding. Understanding the shapes of natural and man-made preparations of HIV-1 Envs will assist the development of effective vaccines against the virus. Here, we evaluate the effects of several Env modifications commonly used to produce Env preparations for vaccine studies and the determination of structure. We found that the cleavage of the HIV-1 Env precursor helps Env to assume its natural shape, which resists the binding of many commonly elicited antibodies. Stabilized soluble Envs exhibit more compact shapes but expose some Env elements differently than the natural Env.
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5
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Nguyen HT, Madani N, Ding H, Elder E, Princiotto A, Gu C, Darby P, Alin J, Herschhorn A, Kappes JC, Mao Y, Sodroski JG. Evaluation of the contribution of the transmembrane region to the ectodomain conformation of the human immunodeficiency virus (HIV-1) envelope glycoprotein. Virol J 2017; 14:33. [PMID: 28209172 PMCID: PMC5314615 DOI: 10.1186/s12985-017-0704-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 02/10/2017] [Indexed: 12/26/2022] Open
Abstract
Background The human immunodeficiency virus (HIV-1) envelope glycoprotein (Env), a Type 1 transmembrane protein, assembles into a trimeric spike complex that mediates virus entry into host cells. The high potential energy of the metastable, unliganded Env trimer is maintained by multiple non-covalent contacts among the gp120 exterior and gp41 transmembrane Env subunits. Structural studies suggest that the gp41 transmembrane region forms a left-handed coiled coil that contributes to the Env trimer interprotomer contacts. Here we evaluate the contribution of the gp41 transmembrane region to the folding and stability of Env trimers. Methods Multiple polar/charged amino acid residues, which hypothetically disrupt the stop-transfer signal, were introduced in the proposed lipid-interactive face of the transmembrane coiled coil, allowing release of soluble cleavage-negative Envs containing the modified transmembrane region (TMmod). We also examined effects of cleavage, the cytoplasmic tail and a C-terminal fibritin trimerization (FT) motif on oligomerization, antigenicity and functionality of soluble and membrane-bound Envs. Results The introduction of polar/charged amino acids into the transmembrane region resulted in the secretion of soluble Envs from the cell. However, these TMmod Envs primarily formed dimers. By contrast, control cleavage-negative sgp140 Envs lacking the transmembrane region formed soluble trimers, dimers and monomers. TMmod and sgp140 trimers were stabilized by the addition of a C-terminal FT sequence, but still exhibited carbohydrate and antigenic signatures of a flexible ectodomain structure. On the other hand, detergent-solubilized cleaved and uncleaved Envs isolated from the membranes of expressing cells exhibited "tighter” ectodomain structures, based on carbohydrate modifications. These trimers were found to be unstable in detergent solutions, but could be stabilized by the addition of a C-terminal FT moiety. The C-terminal FT domain decreased Env cleavage and syncytium-forming ability by approximately three-fold; alteration of the FT trimerization interface restored Env cleavage and syncytium formation to near-wild-type levels. Conclusion The modified transmembrane region was not conducive to trimerization of soluble Envs. However, for HIV-1 Env ectodomains that are minimally modified, membrane-anchored Envs exhibit the most native structures and can be stabilized by appropriately positioned FT domains.
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Affiliation(s)
- Hanh T Nguyen
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Department of Microbiology and Immunobiology, Harvard Medical School, 450 Brookline Avenue, CLS 1010, Boston, MA, 02215, USA
| | - Navid Madani
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Department of Microbiology and Immunobiology, Harvard Medical School, 450 Brookline Avenue, CLS 1010, Boston, MA, 02215, USA
| | - Haitao Ding
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Emerald Elder
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Department of Microbiology and Immunobiology, Harvard Medical School, 450 Brookline Avenue, CLS 1010, Boston, MA, 02215, USA
| | - Amy Princiotto
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Department of Microbiology and Immunobiology, Harvard Medical School, 450 Brookline Avenue, CLS 1010, Boston, MA, 02215, USA
| | - Christopher Gu
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Department of Microbiology and Immunobiology, Harvard Medical School, 450 Brookline Avenue, CLS 1010, Boston, MA, 02215, USA
| | - Patrice Darby
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Department of Microbiology and Immunobiology, Harvard Medical School, 450 Brookline Avenue, CLS 1010, Boston, MA, 02215, USA
| | - James Alin
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Department of Microbiology and Immunobiology, Harvard Medical School, 450 Brookline Avenue, CLS 1010, Boston, MA, 02215, USA
| | - Alon Herschhorn
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Department of Microbiology and Immunobiology, Harvard Medical School, 450 Brookline Avenue, CLS 1010, Boston, MA, 02215, USA
| | - John C Kappes
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.,Birmingham Veterans Affairs Medical Center, Research Service, Birmingham, AL, 35233, USA
| | - Youdong Mao
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Department of Microbiology and Immunobiology, Harvard Medical School, 450 Brookline Avenue, CLS 1010, Boston, MA, 02215, USA
| | - Joseph G Sodroski
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Department of Microbiology and Immunobiology, Harvard Medical School, 450 Brookline Avenue, CLS 1010, Boston, MA, 02215, USA. .,Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA, 02215, USA.
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6
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Witt KC, Castillo-Menendez L, Ding H, Espy N, Zhang S, Kappes JC, Sodroski J. Antigenic characterization of the human immunodeficiency virus (HIV-1) envelope glycoprotein precursor incorporated into nanodiscs. PLoS One 2017; 12:e0170672. [PMID: 28151945 PMCID: PMC5289478 DOI: 10.1371/journal.pone.0170672] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 01/09/2017] [Indexed: 01/13/2023] Open
Abstract
The entry of human immunodeficiency virus (HIV-1) into host cells is mediated by the viral envelope glycoproteins (Envs), which are derived by the proteolytic cleavage of a trimeric gp160 Env precursor. The mature Env trimer is a major target for entry inhibitors and vaccine-induced neutralizing antibodies. Env interstrain variability, conformational flexibility and heavy glycosylation contribute to evasion of the host immune response, and create challenges for structural characterization and vaccine development. Here we investigate variables associated with reconstitution of the HIV-1 Env precursor into nanodiscs, nanoscale lipid bilayer discs enclosed by membrane scaffolding proteins. We identified detergents, as well as lipids similar in composition to the viral lipidome, that allowed efficient formation of Env-nanodiscs (Env-NDs). Env-NDs were created with the full-length Env precursor and with an Env precursor with the majority of the cytoplasmic tail intact. The self-association of Env-NDs was decreased by glutaraldehyde crosslinking. The Env-NDs exhibited an antigenic profile expected for the HIV-1 Env precursor. Env-NDs were recognized by broadly neutralizing antibodies. Of note, neutralizing antibody epitopes in the gp41 membrane-proximal external region and in the gp120:gp41 interface were well exposed on Env-NDs compared with Env expressed on cell surfaces. Most Env epitopes recognized by non-neutralizing antibodies were masked on the Env-NDs. This antigenic profile was stable for several days, exhibiting a considerably longer half-life than that of Env solubilized in detergents. Negative selection with weak neutralizing antibodies could be used to improve the antigenic profile of the Env-NDs. Finally, we show that lipid adjuvants can be incorporated into Env-NDs. These results indicate that Env-NDs represent a potentially useful platform for investigating the structural, functional and antigenic properties of the HIV-1 Env trimer in a membrane context.
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Affiliation(s)
- Kristen C. Witt
- Department of Cancer Immunology & Virology, Dana-Farber Cancer Institute, Department of Microbiology & Immunobiology, Harvard Medical School, Boston, MA, United States of America
| | - Luis Castillo-Menendez
- Department of Cancer Immunology & Virology, Dana-Farber Cancer Institute, Department of Microbiology & Immunobiology, Harvard Medical School, Boston, MA, United States of America
| | - Haitao Ding
- Departments of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States of America
| | - Nicole Espy
- Department of Cancer Immunology & Virology, Dana-Farber Cancer Institute, Department of Microbiology & Immunobiology, Harvard Medical School, Boston, MA, United States of America
| | - Shijian Zhang
- Department of Cancer Immunology & Virology, Dana-Farber Cancer Institute, Department of Microbiology & Immunobiology, Harvard Medical School, Boston, MA, United States of America
| | - John C. Kappes
- Departments of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States of America
- Birmingham Veterans Affairs Medical Center, Research Service, Birmingham, AL, United States of America
| | - Joseph Sodroski
- Department of Cancer Immunology & Virology, Dana-Farber Cancer Institute, Department of Microbiology & Immunobiology, Harvard Medical School, Boston, MA, United States of America
- Department of Immunology & Infectious Diseases, Harvard School of Public Health, Boston, MA, United States of America
- * E-mail:
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7
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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.
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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
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8
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Curreli F, Kwon YD, Zhang H, Scacalossi D, Belov DS, Tikhonov AA, Andreev IA, Altieri A, Kurkin AV, Kwong PD, Debnath AK. Structure-Based Design of a Small Molecule CD4-Antagonist with Broad Spectrum Anti-HIV-1 Activity. J Med Chem 2015; 58:6909-6927. [PMID: 26301736 PMCID: PMC4676410 DOI: 10.1021/acs.jmedchem.5b00709] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Earlier we reported the discovery and design of NBD-556 and their analogs which demonstrated their potential as HIV-1 entry inhibitors. However, progress in developing these inhibitors has been stymied by their CD4-agonist properties, an unfavorable trait for use as drug. Here, we demonstrate the successful conversion of a full CD4-agonist (NBD-556) through a partial CD4-agonist (NBD-09027), to a full CD4-antagonist (NBD-11021) by structure-based modification of the critical oxalamide midregion, previously thought to be intolerant of modification. NBD-11021 showed unprecedented neutralization breath for this class of inhibitors, with pan-neutralization against a panel of 56 Env-pseudotyped HIV-1 representing diverse subtypes of clinical isolates (IC50 as low as 270 nM). The cocrystal structure of NBD-11021 complexed to a monomeric HIV-1 gp120 core revealed its detail binding characteristics. The study is expected to provide a framework for further development of NBD series as HIV-1 entry inhibitors for clinical application against AIDS.
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Affiliation(s)
- Francesca Curreli
- Laboratory of Molecular Modeling and Drug Design, Lindsey F. Kimball Research Institute, New York Blood Center, New York, New York 10065, United States
| | - Young Do Kwon
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Hongtao Zhang
- Laboratory of Molecular Modeling and Drug Design, Lindsey F. Kimball Research Institute, New York Blood Center, New York, New York 10065, United States
| | - Daniel Scacalossi
- Laboratory of Molecular Modeling and Drug Design, Lindsey F. Kimball Research Institute, New York Blood Center, New York, New York 10065, United States
| | - Dmitry S. Belov
- EDASA Scientific, Scientific Park, Moscow State University, Leninskie Gory, Bld.75, 77–101b, 119992 Moscow, Russia
| | - Artur A. Tikhonov
- EDASA Scientific, Scientific Park, Moscow State University, Leninskie Gory, Bld.75, 77–101b, 119992 Moscow, Russia
| | - Ivan A. Andreev
- EDASA Scientific, Scientific Park, Moscow State University, Leninskie Gory, Bld.75, 77–101b, 119992 Moscow, Russia
| | - Andrea Altieri
- EDASA Scientific, Scientific Park, Moscow State University, Leninskie Gory, Bld.75, 77–101b, 119992 Moscow, Russia
| | - Alexander V. Kurkin
- EDASA Scientific, Scientific Park, Moscow State University, Leninskie Gory, Bld.75, 77–101b, 119992 Moscow, Russia
| | - Peter D. Kwong
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Asim K. Debnath
- Laboratory of Molecular Modeling and Drug Design, Lindsey F. Kimball Research Institute, New York Blood Center, New York, New York 10065, United States
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9
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Influences on the Design and Purification of Soluble, Recombinant Native-Like HIV-1 Envelope Glycoprotein Trimers. J Virol 2015; 89:12189-210. [PMID: 26311893 DOI: 10.1128/jvi.01768-15] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 08/20/2015] [Indexed: 12/27/2022] Open
Abstract
UNLABELLED We have investigated factors that influence the production of native-like soluble, recombinant trimers based on the env genes of two isolates of human immunodeficiency virus type 1 (HIV-1), specifically 92UG037.8 (clade A) and CZA97.012 (clade C). When the recombinant trimers based on the env genes of isolates 92UG037.8 and CZA97.012 were made according to the SOSIP.664 design and purified by affinity chromatography using broadly neutralizing antibodies (bNAbs) against quaternary epitopes (PGT145 and PGT151, respectively), the resulting trimers are highly stable and they are fully native-like when visualized by negative-stain electron microscopy. They also have a native-like (i.e., abundant) oligomannose glycan composition and display multiple bNAb epitopes while occluding those for nonneutralizing antibodies. In contrast, uncleaved, histidine-tagged Foldon (Fd) domain-containing gp140 proteins (gp140UNC-Fd-His), based on the same env genes, very rarely form native-like trimers, a finding that is consistent with their antigenic and biophysical properties and glycan composition. The addition of a 20-residue flexible linker (FL20) between the gp120 and gp41 ectodomain (gp41ECTO) subunits to make the uncleaved 92UG037.8 gp140-FL20 construct is not sufficient to create a native-like trimer, but a small percentage of native-like trimers were produced when an I559P substitution in gp41ECTO was also present. The further addition of a disulfide bond (SOS) to link the gp120 and gp41 subunits in the uncleaved gp140-FL20-SOSIP protein increases native-like trimer formation to ∼20 to 30%. Analysis of the disulfide bond content shows that misfolded gp120 subunits are abundant in uncleaved CZA97.012 gp140UNC-Fd-His proteins but very rare in native-like trimer populations. The design and stabilization method and the purification strategy are, therefore, all important influences on the quality of trimeric Env proteins and hence their suitability as vaccine components. IMPORTANCE Soluble, recombinant multimeric proteins based on the HIV-1 env gene are current candidate immunogens for vaccine trials in humans. These proteins are generally designed to mimic the native trimeric envelope glycoprotein (Env) that is the target of virus-neutralizing antibodies on the surfaces of virions. The underlying hypothesis is that an Env-mimetic protein may be able to induce antibodies that can neutralize the virus broadly and potently enough for a vaccine to be protective. Multiple different designs for Env-mimetic trimers have been put forth. Here, we used the CZA97.012 and 92UG037.8 env genes to compare some of these designs and determine which ones best mimic virus-associated Env trimers. We conclude that the most widely used versions of CZA97.012 and 92UG037.8 oligomeric Env proteins do not resemble the trimeric Env glycoprotein on HIV-1 viruses, which has implications for the design and interpretation of ongoing or proposed clinical trials of these proteins.
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Binding mode characterization of NBD series CD4-mimetic HIV-1 entry inhibitors by X-ray structure and resistance study. Antimicrob Agents Chemother 2014; 58:5478-91. [PMID: 25001301 DOI: 10.1128/aac.03339-14] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
We previously identified two small-molecule CD4 mimetics--NBD-556 and NBD-557--and synthesized a series of NBD compounds that resulted in improved neutralization activity in a single-cycle HIV-1 infectivity assay. For the current investigation, we selected several of the most active compounds and assessed their antiviral activity on a panel of 53 reference HIV-1 Env pseudoviruses representing diverse clades of clinical isolates. The selected compounds inhibited tested clades with low-micromolar potencies. Mechanism studies indicated that they act as CD4 agonists, a potentially unfavorable therapeutic trait, in that they can bind to the gp120 envelope glycoprotein and initiate a similar physiological response as CD4. However, one of the compounds, NBD-09027, exhibited reduced agonist properties, in both functional and biophysical studies. To understand the binding mode of these inhibitors, we first generated HIV-1-resistant mutants, assessed their behavior with NBD compounds, and determined the X-ray structures of two inhibitors, NBD-09027 and NBD-10007, in complex with the HIV-1 gp120 core at ∼2-Å resolution. Both studies confirmed that the NBD compounds bind similarly to NBD-556 and NBD-557 by inserting their hydrophobic groups into the Phe43 cavity of gp120. The basic nitrogen of the piperidine ring is located in close proximity to D368 of gp120 but it does not form any H-bond or salt bridge, a likely explanation for their nonoptimal antagonist properties. The results reveal the structural and biological character of the NBD series of CD4 mimetics and identify ways to reduce their agonist properties and convert them to antagonists.
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Ringe RP, Sanders RW, Yasmeen A, Kim HJ, Lee JH, Cupo A, Korzun J, Derking R, van Montfort T, Julien JP, Wilson IA, Klasse PJ, Ward AB, Moore JP. Cleavage strongly influences whether soluble HIV-1 envelope glycoprotein trimers adopt a native-like conformation. Proc Natl Acad Sci U S A 2013; 110:18256-61. [PMID: 24145402 PMCID: PMC3831437 DOI: 10.1073/pnas.1314351110] [Citation(s) in RCA: 155] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We compare the antigenicity and conformation of soluble, cleaved vs. uncleaved envelope glycoprotein (Env gp)140 trimers from the subtype A HIV type 1 (HIV-1) strain BG505. The impact of gp120-gp41 cleavage on trimer structure, in the presence or absence of trimer-stabilizing modifications (i.e., a gp120-gp41 disulfide bond and an I559P gp41 change, together designated SOSIP), was assessed. Without SOSIP changes, cleaved trimers disintegrate into their gp120 and gp41-ectodomain (gp41ECTO) components; when only the disulfide bond is present, they dissociate into gp140 monomers. Uncleaved gp140s remain trimeric whether SOSIP substitutions are present or not. However, negative-stain electron microscopy reveals that only cleaved trimers form homogeneous structures resembling native Env spikes on virus particles. In contrast, uncleaved trimers are highly heterogeneous, adopting a variety of irregular shapes, many of which appear to be gp120 subunits dangling from a central core that is presumably a trimeric form of gp41ECTO. Antigenicity studies with neutralizing and nonneutralizing antibodies are consistent with the EM images; cleaved, SOSIP-stabilized trimers express quaternary structure-dependent epitopes, whereas uncleaved trimers expose nonneutralizing gp120 and gp41ECTO epitopes that are occluded on cleaved trimers. These findings have adverse implications for using soluble, uncleaved trimers for structural studies, and the rationale for testing uncleaved trimers as vaccine candidates also needs to be reevaluated.
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Affiliation(s)
- Rajesh P. Ringe
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065
| | - Rogier W. Sanders
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065
- Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, 1105 AZ, Amsterdam, The Netherlands; and
| | - Anila Yasmeen
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065
| | - Helen J. Kim
- Department of Integrative Structural and Computational Biology, International AIDS Vaccine Initiative Neutralizing Antibody Center and Center for HIV/AIDS Vaccine Immunology & Immunogen Discovery and
| | - Jeong Hyun Lee
- Department of Integrative Structural and Computational Biology, International AIDS Vaccine Initiative Neutralizing Antibody Center and Center for HIV/AIDS Vaccine Immunology & Immunogen Discovery and
| | - Albert Cupo
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065
| | - Jacob Korzun
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065
| | - Ronald Derking
- Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, 1105 AZ, Amsterdam, The Netherlands; and
| | - Thijs van Montfort
- Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, 1105 AZ, Amsterdam, The Netherlands; and
| | - Jean-Philippe Julien
- Department of Integrative Structural and Computational Biology, International AIDS Vaccine Initiative Neutralizing Antibody Center and Center for HIV/AIDS Vaccine Immunology & Immunogen Discovery and
- Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037
| | - Ian A. Wilson
- Department of Integrative Structural and Computational Biology, International AIDS Vaccine Initiative Neutralizing Antibody Center and Center for HIV/AIDS Vaccine Immunology & Immunogen Discovery and
- Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037
| | - Per Johan Klasse
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065
| | - Andrew B. Ward
- Department of Integrative Structural and Computational Biology, International AIDS Vaccine Initiative Neutralizing Antibody Center and Center for HIV/AIDS Vaccine Immunology & Immunogen Discovery and
| | - John P. Moore
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065
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A next-generation cleaved, soluble HIV-1 Env trimer, BG505 SOSIP.664 gp140, expresses multiple epitopes for broadly neutralizing but not non-neutralizing antibodies. PLoS Pathog 2013; 9:e1003618. [PMID: 24068931 PMCID: PMC3777863 DOI: 10.1371/journal.ppat.1003618] [Citation(s) in RCA: 738] [Impact Index Per Article: 67.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 07/30/2013] [Indexed: 01/17/2023] Open
Abstract
A desirable but as yet unachieved property of a human immunodeficiency virus type 1 (HIV-1) vaccine candidate is the ability to induce broadly neutralizing antibodies (bNAbs). One approach to the problem is to create trimeric mimics of the native envelope glycoprotein (Env) spike that expose as many bNAb epitopes as possible, while occluding those for non-neutralizing antibodies (non-NAbs). Here, we describe the design and properties of soluble, cleaved SOSIP.664 gp140 trimers based on the subtype A transmitted/founder strain, BG505. These trimers are highly stable, more so even than the corresponding gp120 monomer, as judged by differential scanning calorimetry. They are also homogenous and closely resemble native virus spikes when visualized by negative stain electron microscopy (EM). We used several techniques, including ELISA and surface plasmon resonance (SPR), to determine the relationship between the ability of monoclonal antibodies (MAbs) to bind the soluble trimers and neutralize the corresponding virus. In general, the concordance was excellent, in that virtually all bNAbs against multiple neutralizing epitopes on HIV-1 Env were highly reactive with the BG505 SOSIP.664 gp140 trimers, including quaternary epitopes (CH01, PG9, PG16 and PGT145). Conversely, non-NAbs to the CD4-binding site, CD4-induced epitopes or gp41ECTO did not react with the trimers, even when their epitopes were present on simpler forms of Env (e.g. gp120 monomers or dissociated gp41 subunits). Three non-neutralizing MAbs to V3 epitopes did, however, react strongly with the trimers but only by ELISA, and not at all by SPR and to only a limited extent by EM. These new soluble trimers are useful for structural studies and are being assessed for their performance as immunogens.
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Isik G, Chung NPY, van Montfort T, Menis S, Matthews K, Schief WR, Moore JP, Sanders RW. An HIV-1 envelope glycoprotein trimer with an embedded IL-21 domain activates human B cells. PLoS One 2013; 8:e67309. [PMID: 23826263 PMCID: PMC3691133 DOI: 10.1371/journal.pone.0067309] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Accepted: 05/16/2013] [Indexed: 12/17/2022] Open
Abstract
Broadly neutralizing antibodies (bNAbs) that target the HIV-1 envelope glycoproteins (Env) can prevent virus acquisition, but several Env properties limit its ability to induce an antibody response that is of sufficient quantity and quality. The immunogenicity of Env can be increased by fusion to co-stimulatory molecules and here we describe novel soluble Env trimers with embedded interleukin-4 (IL-4) or interleukin-21 (IL-21) domains, designed to activate B cells that recognize Env. In particular, the chimeric EnvIL-21 molecule activated B cells efficiently and induced the differentiation of antibody secreting plasmablast-like cells. We studied whether we could increase the activity of the embedded IL-21 by designing a chimeric IL-21/IL-4 (ChimIL-21/4) molecule and by introducing amino acid substitutions in the receptor binding domain of IL-21 that were predicted to enhance its binding. In addition, we incorporated IL-21 into a cleavable Env trimer and found that insertion of IL-21 did not impair Env cleavage, while Env cleavage did not impair IL-21 activity. These studies should guide the further design of chimeric proteins and EnvIL-21 may prove useful in improving antibody responses against HIV-1.
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Affiliation(s)
- Gözde Isik
- Laboratory of Experimental Virology, Department of Medical Microbiology Center for Infection and Immunity Amsterdam, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Nancy P. Y. Chung
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York, United States of America
| | - Thijs van Montfort
- Laboratory of Experimental Virology, Department of Medical Microbiology Center for Infection and Immunity Amsterdam, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Sergey Menis
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
- IAVI Neutralizing Antibody Center and Department of Immunology and Microbial Sciences, The Scripps Research Institute, San Diego, California, United States of America
| | - Katie Matthews
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York, United States of America
| | - William R. Schief
- Department of Immunology and Microbial Science, The Scripps Research Institute, San Diego, California, United States of America
- IAVI Neutralizing Antibody Center, The Scripps Research Institute, San Diego, California, United States of America
- Scripps Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, The Scripps Research Institute, San Diego, California, United States of America
| | - John P. Moore
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York, United States of America
| | - Rogier W. Sanders
- Laboratory of Experimental Virology, Department of Medical Microbiology Center for Infection and Immunity Amsterdam, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York, United States of America
- * E-mail:
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Isik G, van Montfort T, Boot M, Cobos Jiménez V, Kootstra NA, Sanders RW. Chimeric HIV-1 envelope glycoproteins with potent intrinsic granulocyte-macrophage colony-stimulating factor (GM-CSF) activity. PLoS One 2013; 8:e60126. [PMID: 23565193 PMCID: PMC3615126 DOI: 10.1371/journal.pone.0060126] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Accepted: 02/21/2013] [Indexed: 11/18/2022] Open
Abstract
HIV-1 acquisition can be prevented by broadly neutralizing antibodies (BrNAbs) that target the envelope glycoprotein complex (Env). An ideal vaccine should therefore be able to induce BrNAbs that can provide immunity over a prolonged period of time, but the low intrinsic immunogenicity of HIV-1 Env makes the elicitation of such BrNAbs challenging. Co-stimulatory molecules can increase the immunogenicity of Env and we have engineered a soluble chimeric Env trimer with an embedded granulocyte-macrophage colony-stimulating factor (GM-CSF) domain. This chimeric molecule induced enhanced B and helper T cell responses in mice compared to Env without GM-CSF. We studied whether we could optimize the activity of the embedded GM-CSF as well as the antigenic structure of the Env component of the chimeric molecule. We assessed the effect of truncating GM-CSF, removing glycosylation-sites in GM-CSF, and adjusting the linker length between GM-CSF and Env. One of our designed Env(GM-CSF) chimeras improved GM-CSF-dependent cell proliferation by 6-fold, reaching the same activity as soluble recombinant GM-CSF. In addition, we incorporated GM-CSF into a cleavable Env trimer and found that insertion of GM-CSF did not compromise Env cleavage, while Env cleavage did not compromise GM-CSF activity. Importantly, these optimized Env(GM-CSF) proteins were able to differentiate human monocytes into cells with a macrophage-like phenotype. Chimeric Env(GM-CSF) should be useful for improving humoral immunity against HIV-1 and these studies should inform the design of other chimeric proteins.
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Affiliation(s)
- Gözde Isik
- Department of Medical Microbiology, Laboratory of Experimental Virology, Center for Infection and Immunity Amsterdam, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Thijs van Montfort
- Department of Medical Microbiology, Laboratory of Experimental Virology, Center for Infection and Immunity Amsterdam, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Maikel Boot
- Department of Medical Microbiology, Laboratory of Experimental Virology, Center for Infection and Immunity Amsterdam, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Viviana Cobos Jiménez
- Department of Experimental Immunology, Sanquin Research, Landsteiner Laboratory, Center for Infection and Immunity Amsterdam, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Neeltje A. Kootstra
- Department of Experimental Immunology, Sanquin Research, Landsteiner Laboratory, Center for Infection and Immunity Amsterdam, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Rogier W. Sanders
- Department of Medical Microbiology, Laboratory of Experimental Virology, Center for Infection and Immunity Amsterdam, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, United States of America
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van Gils MJ, Sanders RW. Broadly neutralizing antibodies against HIV-1: templates for a vaccine. Virology 2013; 435:46-56. [PMID: 23217615 DOI: 10.1016/j.virol.2012.10.004] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Accepted: 10/01/2012] [Indexed: 11/30/2022]
Abstract
The need for an effective vaccine to prevent the global spread of human immunodeficiency virus type 1 (HIV-1) is well recognized. Passive immunization and challenge studies in non-human primates testify that broadly neutralizing antibodies (BrNAbs) can accomplish protection against infection. In recent years, the introduction of new techniques has facilitated the discovery of an unprecedented number of new human BrNAbs that target and delineate diverse conserved epitopes on the envelope glycoprotein spike (Env). The epitopes of these BrNAbs can serve as templates for immunogen design aimed to induce similar antibodies. Here we will review the characteristics of the different classes of BrNAbs and their target epitopes, as well as factors associated with their development and implications for vaccine design.
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Affiliation(s)
- Marit J van Gils
- Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam, Academic Medical Center, University of Amsterdam, The Netherlands
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Proteolytic processing of the human immunodeficiency virus envelope glycoprotein precursor decreases conformational flexibility. J Virol 2012; 87:1884-9. [PMID: 23175369 DOI: 10.1128/jvi.02765-12] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The mature envelope glycoprotein (Env) spike on the surface of human immunodeficiency virus type 1 (HIV-1) virions is derived by proteolytic cleavage of a trimeric gp160 glycoprotein precursor. Remarkably, proteolytic processing of the HIV-1 Env precursor results in changes in Env antigenicity that resemble those associated with glutaraldehyde fixation. Apparently, proteolytic processing of the HIV-1 Env precursor decreases conformational flexibility of the Env trimeric complex, differentially affecting the integrity/accessibility of epitopes for neutralizing and nonneutralizing antibodies.
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Sanders RW. Clinical evaluation of a soluble trimeric HIV-1 envelope glycoprotein vaccine. Expert Rev Vaccines 2012; 10:1117-20. [PMID: 21854306 DOI: 10.1586/erv.11.97] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Designing an HIV-1 envelope glycoprotein (Env) that can induce broadly neutralizing antibodies in humans remains one of the great challenges in biomedical research. Monomeric gp120 has repeatedly failed to induce cross-neutralizing antibodies in clinical trials. Spearman et al. vaccinated uninfected volunteers with a trimeric gp140 protein. They found that the vaccine was safe and induced neutralizing antibody responses against the homologous virus, but not cross-neutralizing responses. The results reinforce the notion that our Env vaccine design needs to improve.
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Affiliation(s)
- Rogier W Sanders
- Laboratory of Experimental Virology, Department of Medical Microbiology, Academic Medical Center of the University of Amsterdam, Amsterdam The Netherlands.
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Chakrabarti BK, Pancera M, Phogat S, O'Dell S, McKee K, Guenaga J, Robinson J, Mascola J, Wyatt RT. HIV type 1 Env precursor cleavage state affects recognition by both neutralizing and nonneutralizing gp41 antibodies. AIDS Res Hum Retroviruses 2011; 27:877-87. [PMID: 21158699 DOI: 10.1089/aid.2010.0281] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
HIV-1 is relatively resistant to antibody-mediated neutralization; however, rare antibodies to the exterior envelope glycoprotein, gp120, and the transmembrane glycoprotein, gp41, can neutralize a broad array of isolates. Two antibodies, 2F5 and 4E10, are directed against the gp41 membrane proximal external region (MPER); however, the kinetic neutralization signature of these antibodies remains unresolved. Previously, we reported that the fully cleaved, cell surface envelope glycoproteins (Env) derived from the primary isolate, JR-FL, are well recognized exclusively by gp120-directed neutralizing ligands and not by nonneutralizing gp120 antibodies. However, the gp120 nonneutralizing antibodies can recognize HIV spikes that are rendered fully cleavage defective by site-directed mutagenesis. Here, we extended such analysis to gp41 neutralizing and nonneutralizing antibodies and, relative to the rules of gp120-specific antibody recognition, we observed marked contrasts. Similar to gp120 recognition, the nonneutralizing gp41 cluster 1 or cluster 2 antibodies bound much more efficiently to cleavage-defective spikes when compared to their recognition of cleaved spikes. In contrast to gp120 neutralizing antibody recognition, the broadly neutralizing gp41 antibodies 2F5 and 4E10, like the nonneutralizing gp41 antibodies, did not efficiently recognize the predominantly cleaved, primary isolate JR-FL spikes. However, if the spikes were rendered cleavage defective, recognition by both the neutralizing and nonneutralizing ligand markedly increased. CD4 interaction with the cleaved spikes markedly increased recognition by most nonneutralizing gp41 antibodies, whereas such treatment had a minimal increase of 2F5 and 4E10 recognition. These data indicate again the profound influence that cleavage imposes on the quaternary packing of primary isolate spikes and have important implications for soluble trimer candidate immunogens.
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Affiliation(s)
| | - Marie Pancera
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland
| | - Sanjay Phogat
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland
| | - Sijy O'Dell
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland
| | - Krisha McKee
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland
| | - Javier Guenaga
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland
| | | | - John Mascola
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland
| | - Richard T. Wyatt
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland
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Melchers M, Matthews K, de Vries RP, Eggink D, van Montfort T, Bontjer I, van de Sandt C, David K, Berkhout B, Moore JP, Sanders RW. A stabilized HIV-1 envelope glycoprotein trimer fused to CD40 ligand targets and activates dendritic cells. Retrovirology 2011; 8:48. [PMID: 21689404 PMCID: PMC3141652 DOI: 10.1186/1742-4690-8-48] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Accepted: 06/20/2011] [Indexed: 12/22/2022] Open
Abstract
Background One reason why subunit protein and DNA vaccines are often less immunogenic than live-attenuated and whole-inactivated virus vaccines is that they lack the co-stimulatory signals provided by various components of the more complex vaccines. The HIV-1 envelope glycoprotein complex (Env) is no exception to this rule. Other factors that limit the induction of neutralizing antibodies against HIV-1 lie in the structure and instability of Env. We have previously stabilized soluble trimeric mimics of Env by introducing a disulfide bond between gp120 and gp41 and adding a trimer stabilizing mutation in gp41 (SOSIP.R6 gp140). Results We further stabilized the SOSIP.R6 gp140 using a GCN4-based isoleucine zipper motif, creating SOSIP.R6-IZ gp140. In order to target SOSIP.R6-IZ to immune cells, including dendritic cells, while at the same time activating these cells, we fused SOSIP.R6-IZ to the active domain of CD40 ligand (CD40L), which may serve as a 'cis-adjuvant'. The Env component of the SOSIP.R6-IZ-CD40L fusion construct bound to CD4 and neutralizing antibodies, while the CD40L moiety interacted with CD40. Furthermore, the chimeric molecule was able to signal efficiently through CD40 and induce maturation of human dendritic cells. Dendritic cells secreted IL-6, IL-10 and IL-12 in response to stimulation by SOSIP.R6-IZ-CD40L and were able to activate naïve T cells. Conclusions Chimeric HIV-1 gp140 - CD40L trimers can target and activate dendritic cells. Targeting and activating immune cells using CD40L and other 'cis-adjuvants' may improve subunit protein vaccine immunogenicity for HIV-1 and other infectious diseases.
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Affiliation(s)
- Mark Melchers
- Laboratory of Experimental Virology, Department of Medical Microbiology Center for Infection and Immunity Amsterdam, Netherlands
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Direct antibody access to the HIV-1 membrane-proximal external region positively correlates with neutralization sensitivity. J Virol 2011; 85:8217-26. [PMID: 21653673 DOI: 10.1128/jvi.00756-11] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
On the prereceptor-engaged HIV-1 envelope glycoprotein (Env) spike, epitope access by the membrane-proximal external region (MPER)-directed broadly neutralizing antibodies 2F5 and 4E10 remains unresolved. Data on binding to cell surface Env and entry data using primary isolates suggest inaccessibility of the 2F5 and 4E10 epitopes on the viral spike prior to receptor engagement, but trimer gel shift analysis and slow kinetics of shedding induced by 2F5 and 4E10 indicate otherwise. Therefore, it remains unclear if the epitopes themselves are formed in their antibody-bound state (or at least sampled) prior to receptor/coreceptor engagement or if receptor interactions both expose and form the MPER epitopes, presumably in the putative prefusion transitional intermediate. Here, we performed antibody-virus "washout experiments" using both lab-adapted and a panel of clade B primary isolates to analyze MPER accessibility. The neutralization activity of 2F5 and 4E10 against lab-adapted viruses and sensitive and moderately resistant viruses was largely unaffected by relatively rapid antibody-virus washing, suggesting direct interaction with the "static" spike. However, for more neutralization-resistant viruses, the 2F5 and 4E10 antibodies could neutralize only under the "no antibody-virus wash" conditions, implying that the MPER epitopes were not accessible prior to receptor engagement. Accessibility in the washout conditions could be precisely predicted by the relative resistance to neutralization in a standard neutralization format. These data are consistent with a model in which the local MPER antibody epitope conformations may be sampled on the native spike but are occluded to antibody by local steric or distal quaternary constraints adopted by highly resistant HIV-1 isolates.
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21
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Bontjer I, Melchers M, Eggink D, David K, Moore JP, Berkhout B, Sanders RW. Stabilized HIV-1 envelope glycoprotein trimers lacking the V1V2 domain, obtained by virus evolution. J Biol Chem 2010; 285:36456-70. [PMID: 20826824 DOI: 10.1074/jbc.m110.156588] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The envelope glycoproteins (Env) are the focus of HIV-1 vaccine development strategies based on the induction of humoral immunity, but the mechanisms the virus has evolved to limit the induction and binding of neutralizing antibodies (NAbs) constitute substantial obstacles. Conserved neutralization epitopes are shielded by variable regions and carbohydrates, so one strategy to increase their exposure and, it is hoped, their immunogenicity is to delete the overlying variable loops. However, deleting the variable regions from Env trimers can be problematic, because hydrophobic patches that are normally solvent-inaccessible now become exposed, causing protein misfolding or aggregation, for example. Here, we describe the construction and characterization of recombinant gp140 trimers lacking variable domains 1 and 2 (ΔV1V2). The design of the trimers was guided by HIV-1 evolution studies that identified compensatory changes in V1V2-deleted but functional Env proteins (Bontjer, I., Land, A., Eggink, D., Verkade, E., Tuin, K., Baldwin, C., Pollakis, G., Paxton, W. A., Braakman, I., Berkhout, B., and Sanders, R. W. (2009) J. Virol. 83, 368-383). We now show that specific compensatory changes improved the function of ΔV1V2 Env proteins and hence HIV-1 replication. The changes acted by reducing the exposure of a hydrophobic surface either by replacing a hydrophobic residue with a hydrophilic one or by covering the surface with a glycan. The compensatory changes allowed the efficient expression of well folded, soluble gp140 trimers derived from various HIV-1 isolates. The evolved ΔV1V2 Env viruses were extremely sensitive to NAbs, indicating that neutralization epitopes are well exposed, which was confirmed by studies of NAb binding to the soluble ΔV1V2 gp140 trimers. These evolved ΔV1V2 trimers could be useful reagents for immunogenicity and structural studies.
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Affiliation(s)
- Ilja Bontjer
- Laboratory of Experimental Virology, Department of Medical Microbiology, Academic Medical Center of the University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
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Alterations in the immunogenic properties of soluble trimeric human immunodeficiency virus type 1 envelope proteins induced by deletion or heterologous substitutions of the V1 loop. J Virol 2010; 84:9932-46. [PMID: 20660181 DOI: 10.1128/jvi.00868-10] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
HIV-1 gp140 envelope immunogens express conserved epitopes that are targeted by broadly cross-reactive neutralizing antibodies, but they fail to elicit similar antibodies upon immunization. The poor immunogenicity of conserved epitopes on gp140 could be linked to the high immunogenicity of variable Env regions on such constructs. Previous studies have shown that the first hypervariable region (V1 loop) is immunogenic on soluble gp140s but elicits type-specific antibodies. To address issues related to the high immunogenicity of the V1 loop, two conceptually opposite approaches were tested. In the first approach, we eliminated the V1 loop from our gp140 construct and examined how V1 deletion altered the immunogenic properties of other Env regions. In the second approach, we took advantage of the high immunogenicity of the V1 loop and engrafted four diverse V1 loops onto a common gp140 Env "scaffold." These four scaffolds were used as a cocktail of immunogens to elicit diverse anti-V1 antibodies, under the hypothesis that eliciting diverse anti-V1 antibodies would expand the neutralizing breadth of immune sera. Our study indicates that three of four heterologous V1 loops were immunogenic on the common Env backbone "scaffold," but heterologous anti-V1 neutralizing responses were observed in only one case. Both types of V1 modification dampened the immunogenicity of the V3 loop, differentially altered the immunogenicity of the transmembrane gp41 subunit, and altered the relative immunogenicities of unknown Env regions, including potentially the CD4-binding site (CD4-bs) and trimer-specific targets, which elicited cross-reactive neutralizing antibodies but of limited breadth.
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Eggink D, Melchers M, Wuhrer M, van Montfort T, Dey AK, Naaijkens BA, David KB, Le Douce V, Deelder AM, Kang K, Olson WC, Berkhout B, Hokke CH, Moore JP, Sanders RW. Lack of complex N-glycans on HIV-1 envelope glycoproteins preserves protein conformation and entry function. Virology 2010; 401:236-47. [PMID: 20304457 DOI: 10.1016/j.virol.2010.02.019] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2009] [Revised: 12/23/2009] [Accepted: 02/13/2010] [Indexed: 10/19/2022]
Abstract
The HIV-1 envelope glycoprotein complex (Env) is the focus of vaccine development aimed at eliciting humoral immunity. Env's extensive and heterogeneous N-linked glycosylation affects folding, binding to lectin receptors, antigenicity and immunogenicity. We characterized recombinant Env proteins and virus particles produced in mammalian cells that lack N-acetylglucosaminyltransferase I (GnTI), an enzyme necessary for the conversion of oligomannose N-glycans to complex N-glycans. Carbohydrate analyses revealed that trimeric Env produced in GnTI(-/-) cells contained exclusively oligomannose N-glycans, with incompletely trimmed oligomannose glycans predominating. The folding and conformation of Env proteins was little affected by the manipulation of the glycosylation. Viruses produced in GnTI(-/-) cells were infectious, indicating that the conversion to complex glycans is not necessary for Env entry function, although virus binding to the C-type lectin DC-SIGN was enhanced. Manipulating Env's N-glycosylation may be useful for structural and functional studies and for vaccine design.
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Affiliation(s)
- Dirk Eggink
- 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
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24
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Abstract
PURPOSE OF REVIEW We summarize and discuss recent developments regarding the immunogenicity of human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) oligomers, focusing, for the most part, on trimeric, recombinant protein immunogens. RECENT FINDINGS The three-dimensional cryo-electron tomography images of the HIV-1 Env trimeric spike, coupled with previous data demonstrating the impact on envelope glycoprotein (gp120)-transmembrane glycoprotein (gp41) cleavage of the architecture of the Env trimers, provide exciting information that may lead to new avenues for novel immunogen design. Through new processes to map region-specific anti-Env antibodies present in immune serum, it is now possible to define antibody specificities against conformationally sensitive surfaces of Env. A number of strategies designed to counteract the immunodominance of the HIV-1 Env variable regions were attempted, and a recent study demonstrates that immunization with Env trimers provides sterilizing protection against mucosal challenge with virus. Importantly, protection against the challenge virus was associated with in-vitro HIV-1 neutralization titers. SUMMARY Several studies within the past 18 months provide exciting structural information and the development of tools that have the potential to improve Env trimer design and the analysis of trimer immunogenicity studies. The ability to predict protection against a challenge virus through an in-vitro neutralization screen may be very helpful for evaluation of immunogens to move forward into clinical trials.
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Yuan W, Li X, Kasterka M, Gorny MK, Zolla-Pazner S, Sodroski J. Oligomer-specific conformations of the human immunodeficiency virus (HIV-1) gp41 envelope glycoprotein ectodomain recognized by human monoclonal antibodies. AIDS Res Hum Retroviruses 2009; 25:319-28. [PMID: 19292593 DOI: 10.1089/aid.2008.0213] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Trimerization of the human immunodeficiency virus (HIV-1) envelope glycoproteins is mediated by the ectodomain of the gp41 transmembrane glycoprotein. Here we investigate oligomer-specific conformations of gp41 by using monoclonal antibodies (MAbs) from HIV-1-infected humans. Human MAbs directed against the cluster I region of gp41 recognized trimeric, dimeric, and monomeric forms of soluble envelope glycoproteins; thus, the integrity of the cluster I epitopes is minimally affected by the oligomeric state. In contrast, human MAbs to the cluster II region were all oligomers specific. One cluster II MAb, 126-6, recognized exclusively the trimeric form of envelope glycoproteins, whereas the others recognized both trimeric and dimeric forms. Thus, a distinct trimer-specific conformation exists in the cluster II region of gp41. Analysis of soluble envelope glycoprotein mutants revealed that gp41 sequences immediately N-terminal to isoleucine 646 contribute to the formation of both the trimer and the trimer-specific conformational epitope.
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Affiliation(s)
- Wen Yuan
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia 22908
- Myles H. Thaler Center for AIDS and Human Retrovirus Research, University of Virginia, Charlottesville, Virginia 22908
| | - Xing Li
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Boston, Massachusetts 02115
- Department of Pathology, Division of AIDS, Harvard Medical School, Boston, Massachusetts 02115
| | - Marta Kasterka
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia 22908
| | - Miroslaw K. Gorny
- Department of Pathology, New York University School of Medicine, New York, New York 10016
| | - Susan Zolla-Pazner
- Department of Pathology, New York University School of Medicine, New York, New York 10016
- Veterans Affairs Medical Center, New York, New York 10010
| | - Joseph Sodroski
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Boston, Massachusetts 02115
- Department of Pathology, Division of AIDS, Harvard Medical School, Boston, Massachusetts 02115
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts 02115
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Identification of a human immunodeficiency virus type 1 envelope glycoprotein variant resistant to cold inactivation. J Virol 2009; 83:4476-88. [PMID: 19211747 DOI: 10.1128/jvi.02110-08] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein trimer consists of gp120 and gp41 subunits and undergoes a series of conformational changes upon binding to the receptors, CD4 and CCR5/CXCR4, that promote virus entry. Surprisingly, we found that the envelope glycoproteins of some HIV-1 strains are functionally inactivated by prolonged incubation on ice. Serial exposure of HIV-1 to extremes of temperature, followed by expansion of replication-competent viruses, allowed selection of a temperature-resistant virus. The envelope glycoproteins of this virus resisted cold inactivation due to a single passage-associated change, H66N, in the gp120 exterior envelope glycoprotein. Histidine 66 is located within the gp41-interactive inner domain of gp120 and, in other studies, has been shown to decrease the sampling of the CD4-bound conformation by unliganded gp120. Substituting asparagine or other amino acid residues for histidine 66 in cold-sensitive HIV-1 envelope glycoproteins resulted in cold-stable phenotypes. Cold inactivation of the HIV-1 envelope glycoproteins occurred even at high pH, indicating that protonation of histidine 66 is not necessary for this process. Increased exposure of epitopes in the ectodomain of the gp41 transmembrane envelope glycoprotein accompanied cold inactivation, but shedding of gp120 did not. An amino acid change in gp120 (S375W) that promotes the CD4-bound state or treatment with soluble CD4 or a small-molecule CD4 mimic resulted in increased cold sensitivity. These results indicate that the CD4-bound intermediate of the HIV-1 envelope glycoproteins is cold labile; avoiding the CD4-bound state increases temperature stability.
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Young KR, McBurney SP, Karkhanis LU, Ross TM. Virus-like particles: designing an effective AIDS vaccine. Methods 2007; 40:98-117. [PMID: 16997718 DOI: 10.1016/j.ymeth.2006.05.024] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2005] [Accepted: 05/05/2006] [Indexed: 01/10/2023] Open
Abstract
Viruses that infect eukaryotic organisms have the unique characteristic of self-assembling into particles. The mammalian immune system is highly attuned to recognizing and attacking these viral particles following infection. The use of particle-based immunogens, often delivered as live-attenuated viruses, has been an effective vaccination strategy for a variety of viruses. The development of an effective vaccine against the human immunodeficiency virus (HIV) has proven to be a challenge, since HIV infects cells of the immune system causing severe immunodeficiency resulting in the syndrome known as AIDS. In addition, the ability of the virus to adapt to immune pressure and reside in an integrated form in host cells presents hurdles for vaccinologists to overcome. A particle-based vaccine strategy has promise for eliciting high titer, long-lived, immune responses to a diverse number of viral epitopes against different HIV antigens. Live-attenuated viruses are effective at generating both cellular and humoral immune responses. However, while these vaccines stimulate immunity, challenged animals rarely clear the viral infection and the degree of attenuation directly correlates with protection from disease. Further, a live-attenuated vaccine has the potential to revert to a pathogenic form. Alternatively, virus-like particles (VLPs) mimic the viral particle without causing an immunodeficiency disease. VLPs are self-assembling, non-replicating, non-pathogenic particles that are similar in size and conformation to intact virions. A variety of VLPs for lentiviruses are currently in preclinical and clinical trials. This review focuses on our current status of VLP-based AIDS vaccines, regarding issues of purification and immune design for animal and clinical trials.
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Affiliation(s)
- Kelly R Young
- Department of Medicine, Division of Infectious Diseases, University of Pittsburgh School of Medicine, PA 15261, USA
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28
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Beddows S, Franti M, Dey AK, Kirschner M, Iyer SPN, Fisch DC, Ketas T, Yuste E, Desrosiers RC, Klasse PJ, Maddon PJ, Olson WC, Moore JP. A comparative immunogenicity study in rabbits of disulfide-stabilized, proteolytically cleaved, soluble trimeric human immunodeficiency virus type 1 gp140, trimeric cleavage-defective gp140 and monomeric gp120. Virology 2006; 360:329-40. [PMID: 17126869 DOI: 10.1016/j.virol.2006.10.032] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2006] [Revised: 08/22/2006] [Accepted: 10/18/2006] [Indexed: 11/16/2022]
Abstract
The human immunodeficiency virus type 1 (HIV-1) surface envelope glycoprotein (Env) complex, a homotrimer containing gp120 surface glycoprotein and gp41 transmembrane glycoprotein subunits, mediates the binding and fusion of the virus with susceptible target cells. The Env complex is the target for neutralizing antibodies (NAbs) and is the basis for vaccines intended to induce NAbs. Early generation vaccines based on monomeric gp120 subunits did not confer protection from infection; one alternative approach is therefore to make and evaluate soluble forms of the trimeric Env complex. We have directly compared the immunogenicity in rabbits of two forms of soluble trimeric Env and monomeric gp120 based on the sequence of HIV-1(JR-FL). Both protein-only and DNA-prime, protein-boost immunization formats were evaluated, DNA-priming having little or no influence on the outcome. One form of trimeric Env was made by disrupting the gp120-gp41 cleavage site by mutagenesis (gp140(UNC)), the other contains an intramolecular disulfide bond to stabilize the cleaved gp120 and gp41 moieties (SOSIP.R6 gp140). Among the three immunogens, SOSIP.R6 gp140 most frequently elicited neutralizing antibodies against the homologous, neutralization-resistant strain, HIV-1(JR-FL). All three proteins induced NAbs against more sensitive strains, but the breadth of activity against heterologous primary isolates was limited. When antibodies able to neutralize HIV-1(JR-FL) were detected, antigen depletion studies showed they were not directed at the V3 region but were targeted at other, undefined gp120 and also non-gp120 epitopes.
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Affiliation(s)
- Simon Beddows
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, 1300 York Avenue, Room W-805, New York, NY 10021, USA
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29
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Kothe DL, Decker JM, Li Y, Weng Z, Bibollet-Ruche F, Zammit KP, Salazar MG, Chen Y, Salazar-Gonzalez JF, Moldoveanu Z, Mestecky J, Gao F, Haynes BF, Shaw GM, Muldoon M, Korber BTM, Hahn BH. Antigenicity and immunogenicity of HIV-1 consensus subtype B envelope glycoproteins. Virology 2006; 360:218-34. [PMID: 17097711 PMCID: PMC1945152 DOI: 10.1016/j.virol.2006.10.017] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Revised: 09/26/2006] [Accepted: 10/06/2006] [Indexed: 11/20/2022]
Abstract
"Centralized" (ancestral and consensus) HIV-1 envelope immunogens induce broadly cross-reactive T cell responses in laboratory animals; however, their potential to elicit cross-reactive neutralizing antibodies has not been fully explored. Here, we report the construction of a panel of consensus subtype B (ConB) envelopes and compare their biologic, antigenic, and immunogenic properties to those of two wild-type Env controls from individuals with early and acute HIV-1 infection. Glycoprotein expressed from full-length (gp160), uncleaved (gp160-UNC), truncated (gp145), and N-linked glycosylation site deleted (gp160-201N/S) versions of the ConB env gene were packaged into virions and, except for the fusion defective gp160-UNC, mediated infection via the CCR5 co-receptor. Pseudovirions containing ConB Envs were sensitive to neutralization by patient plasma and monoclonal antibodies, indicating the preservation of neutralizing epitopes found in contemporary subtype B viruses. When used as DNA vaccines in guinea pigs, ConB and wild-type env immunogens induced appreciable binding, but overall only low level neutralizing antibodies. However, all four ConB immunogens were significantly more potent than one wild-type vaccine at eliciting neutralizing antibodies against a panel of tier 1 and tier 2 viruses, and ConB gp145 and gp160 were significantly more potent than both wild-type vaccines at inducing neutralizing antibodies against tier 1 viruses. Thus, consensus subtype B env immunogens appear to be at least as good as, and in some instances better than, wild-type B env immunogens at inducing a neutralizing antibody response, and are amenable to further improvement by specific gene modifications.
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Affiliation(s)
- Denise L Kothe
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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30
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McBurney SP, Young KR, Ross TM. Membrane embedded HIV-1 envelope on the surface of a virus-like particle elicits broader immune responses than soluble envelopes. Virology 2006; 358:334-46. [PMID: 17011011 DOI: 10.1016/j.virol.2006.08.032] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2006] [Revised: 08/07/2006] [Accepted: 08/22/2006] [Indexed: 11/24/2022]
Abstract
Virally regulated HIV-1 particles were expressed from DNA plasmids encoding Gag, protease, reverse transcriptase, Vpu, Tat, Rev, and Env. The sequences for integrase, Vpr, Vif, Nef, and the long terminal repeats (LTRs) were deleted. Mutations were engineered into the VLP genome to produce particles deficient in activities associated with viral reverse transcriptase, RNase H, and RNA packaging. Each plasmid efficiently secreted particles from primate cells in vitro and particles were purified from the supernatants and used as immunogens. Mice (BALB/c) were vaccinated intranasally (day 1 and weeks 3 and 6) with purified VLPs and the elicited immunity was compared to particles without Env (Gag(p55)), to soluble monomeric Env(gp120), or to soluble trimerized Env(gp140). Only mice vaccinated with VLPs had robust anti-Env cellular immunity. In contrast, all mice had high titer anti-Env serum antibody (IgG). However, VLP-vaccinated mice had antisera that detected a broader number of linear Env peptides, had anti-Env mucosal IgA and IgG, as well as higher titers of serum neutralizing antibodies. VLPs elicited high titer antibodies that recognized linear regions in V4-C5 and the ectodomain of gp41, but did not recognize V3. These lentiviral VLPs are effective mucosal immunogens that elicit broader immunity against Env determinants in both the systemic and mucosal immune compartments than soluble forms of Env.
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Affiliation(s)
- Sean P McBurney
- Center for Vaccine Research for Emerging Diseases and Biodefense, University of Pittsburgh School of Medicine, 9047 Biomedical Sciences Tower 3, 3501 Fifth Avenue, Pittsburgh, PA 15261, USA
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31
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Yuan W, Bazick J, Sodroski J. Characterization of the multiple conformational States of free monomeric and trimeric human immunodeficiency virus envelope glycoproteins after fixation by cross-linker. J Virol 2006; 80:6725-37. [PMID: 16809278 PMCID: PMC1489074 DOI: 10.1128/jvi.00118-06] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) gp120 exterior and gp41 transmembrane envelope glycoproteins assemble into trimers on the virus surface that represent potential targets for antibodies. Potent neutralizing antibodies bind the monomeric gp120 glycoprotein with small changes in entropy, whereas unusually large decreases in entropy accompany gp120 binding by soluble CD4 and less potent neutralizing antibodies. The high degree of conformational flexibility in the free gp120 molecule implied by these observations has been suggested to contribute to masking the trimer from antibodies that recognize the gp120 receptor-binding regions. Here we use cross-linking and recognition by antibodies to investigate the conformational states of gp120 monomers and soluble and cell surface forms of the trimeric HIV-1 envelope glycoproteins. The fraction of monomeric and trimeric envelope glycoproteins able to be recognized after fixation was inversely related to the entropic changes associated with ligand binding. In addition, fixation apparently limited the access of antibodies to the V3 loop and gp41-interactive surface of gp120 only in the context of trimeric envelope glycoproteins. The results support a model in which the unliganded monomeric and trimeric HIV-1 envelope glycoproteins sample several different conformations. Depletion of particular fixed conformations by antibodies allowed characterization of the relationships among the conformational states. Potent neutralizing antibodies recognize the greatest number of conformations and therefore can bind the virion envelope glycoproteins more rapidly and completely than weakly neutralizing antibodies. Thus, the conformational flexibility of the HIV-1 envelope glycoproteins creates thermodynamic and kinetic barriers to neutralization by antibodies directed against the receptor-binding regions of gp120.
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Affiliation(s)
- Wen Yuan
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, 44 Binney Street-JFB 824, Boston, MA 02115, USA
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32
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Beddows S, Kirschner M, Campbell-Gardener L, Franti M, Dey AK, Iyer SPN, Maddon PJ, Paluch M, Master A, Overbaugh J, VanCott T, Olson WC, Moore JP. Construction and characterization of soluble, cleaved, and stabilized trimeric Env proteins based on HIV type 1 Env subtype A. AIDS Res Hum Retroviruses 2006; 22:569-79. [PMID: 16796532 DOI: 10.1089/aid.2006.22.569] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The generation of an antibody response capable of neutralizing a broad range of clinical isolates remains an important goal of human immunodeficiency virus type 1 (HIV-1) vaccine development. Envelope glycoprotein (Env)-based vaccine candidates will also need to take into account the extensive genetic diversity of circulating HIV-1 strains. We describe here the generation of soluble, stabilized, proteolytically cleaved, trimeric forms of Env (SOSIP gp140 proteins) based on contemporary Env subtype A viruses from East Africa. We discuss issues associated with the construction, purification, and characterization of such complex proteins; not all env sequences allow the expression of trimeric proteins. However, stabilized trimers from one such protein, KNH1144 SOSIP gp140, were successfully made. These proteins are now being prepared for preclinical immunogenicity studies.
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Affiliation(s)
- Simon Beddows
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York 10021, USA
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Herrera C, Klasse PJ, Kibler CW, Michael E, Moore JP, Beddows S. Dominant-negative effect of hetero-oligomerization on the function of the human immunodeficiency virus type 1 envelope glycoprotein complex. Virology 2006; 351:121-32. [PMID: 16616288 DOI: 10.1016/j.virol.2006.03.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2006] [Revised: 02/23/2006] [Accepted: 03/03/2006] [Indexed: 11/29/2022]
Abstract
The human immunodeficiency virus type 1 (HIV-1) envelope (Env) glycoprotein forms trimers that mediate interactions with the CD4 receptor and a co-receptor on the target cell surface, thereby triggering viral fusion with the cell membrane. Cleavage of Env into its surface, gp120, and transmembrane, gp41, moieties is necessary for activation of its fusogenicity. Here, we produced pseudoviruses with phenotypically mixed wild-type (Wt) and mutant, cleavage-incompetent Env in order to quantify the effects of incorporating uncleaved Env on virion infectivity, antigenicity and neutralization sensitivity. We modeled the relative infectivity of three such phenotypically mixed viral strains, JR-FL, HXBc2 and a derivative of the latter, 3.2P, as a function of the relative amount of Wt Env. The data were fit very closely (R(2) > 0.99) by models which assumed that only Wt homotrimers were functional, with different approximate thresholds of critical numbers of functional trimers per virion for the three strains. We also produced 3.2P pseudoviruses containing both a cleavage-competent Env that is defective for binding the neutralizing monoclonal antibody (NAb) 2G12, and a cleavage-incompetent Env that binds 2G12. The 2G12 NAb was not able to reduce the infectivity of these pseudoviruses detectably. Their neutralization by the CD4-binding site-directed agents CD4-IgG2 and NAb b12 was also unaffected by 2G12 binding to uncleaved Env. These results further strengthen the conclusion that only homotrimers consisting of cleaved Env are functional. They also imply that the function of a trimer is unaffected sterically by the binding of an antibody to an adjacent trimer.
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Affiliation(s)
- Carolina Herrera
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, NY 10021, USA
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34
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Bower JF, Li Y, Wyatt R, Ross TM. HIV-1 Envgp140 trimers elicit neutralizing antibodies without efficient induction of conformational antibodies. Vaccine 2006; 24:5442-51. [PMID: 16621193 DOI: 10.1016/j.vaccine.2006.03.063] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Currently, no vaccine for human immunodeficiency virus (HIV-1) provides protection from virus infection. One reason for these disappointing results has been the difficulty of current vaccine candidates to elicit high-titer, broadly reactive immunity to a large number of viral proteins. Recently, our laboratory demonstrated that the coupling of C3d to a soluble trimerized HIV-1 envelope (Env(gp140(FT))) elicited higher titers of neutralizing antibodies than monomers of Env(gp120) coupled to C3d [Bower JF, Yang X, Sodroski J, Ross TM. Elicitation of neutralizing antibodies with DNA vaccines expressing soluble stabilized human immunodeficiency virus type 1 envelope glycoprotein trimers conjugated to C3d. J Virol 2004;78(9):4710-9]. To determine if the induction of conformational antibodies correlated with neutralization, mice (BALB/c) were primed (2x) with DNA plasmids expressing monomeric Env(gp120) or trimeric Env(gp140) alone or fused to mC3d(3) at one of two doses (2.0microg or 0.2microg), followed by a boost of recombinant uncleaved, trimeric Env(gp140). Regardless of the priming dose of DNA, all mice had high-titer anti-Env IgG antibodies. Interestingly, Env(gp140) trimers did not elicit higher titers of antibodies that recognized conformational Env epitopes compared to monomers of Env(gp120). Therefore, additional parameters were examined for correlation with neutralization. For neutralization-resistant HIV-1 isolates, ADA and YU-2, neutralization correlated with high-titer, high avidity antibodies, with Env(gp140) eliciting slightly higher neutralization titers than Env(gp120). In contrast, none of the measured parameters correlated with neutralization for the more neutralization-sensitive isolates, MN or 89.6. Therefore, even though soluble, uncleaved Env(gp140) trimers may be marginally more effective at eliciting neutralizing antibodies than Env(gp120), neutralization does not appear to correlate with the elicitation of conformationally dependent antibodies.
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Affiliation(s)
- Joseph F Bower
- University of Pittsburgh, School of Medicine, Department of Medicine, Division of Infectious Diseases, Scaife Hall, Room S871, 3550 Terrace Street, Pittsburgh, PA 15261, USA.
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35
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Yang X, Kurteva S, Ren X, Lee S, Sodroski J. Stoichiometry of envelope glycoprotein trimers in the entry of human immunodeficiency virus type 1. J Virol 2005; 79:12132-47. [PMID: 16160141 PMCID: PMC1211524 DOI: 10.1128/jvi.79.19.12132-12147.2005] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) envelope glycoproteins (Envs) function as a trimer, mediating virus entry by promoting the fusion of the viral and target cell membranes. HIV-1 Env trimers induce membrane fusion through a pH-independent pathway driven by the interaction between an Env trimer and its cellular receptors, CD4 and CCR5/CXCR4. We studied viruses with mixed heterotrimers of wild-type and dominant-negative Envs to determine the number (T) of Env trimers required for HIV-1 entry. To our surprise, we found that a single Env trimer is capable of supporting HIV-1 entry; i.e., T = 1. A similar approach was applied to investigate the entry stoichiometry of envelope glycoproteins from amphotropic murine leukemia virus (A-MLV), avian sarcoma/leukosis virus type A (ASLV-A), and influenza A virus. When pseudotyped on HIV-1 virions, the A-MLV and ASLV-A Envs also exhibit a T = 1 entry stoichiometry. In contrast, eight to nine influenza A virus hemagglutinin trimers function cooperatively to achieve membrane fusion and virus entry, using a pH-dependent pathway. The different entry requirements for cooperativity among Env trimers for retroviruses and influenza A virus may influence viral strategies for replication and evasion of the immune system.
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Affiliation(s)
- Xinzhen Yang
- Dana-Farber Cancer Institute, Department of Cancer Immunology and AIDS, 44 Binney Street, JFB 824, Boston, MA 02115, USA.
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36
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Herrera C, Klasse PJ, Michael E, Kake S, Barnes K, Kibler CW, Campbell-Gardener L, Si Z, Sodroski J, Moore JP, Beddows S. The impact of envelope glycoprotein cleavage on the antigenicity, infectivity, and neutralization sensitivity of Env-pseudotyped human immunodeficiency virus type 1 particles. Virology 2005; 338:154-72. [PMID: 15932765 DOI: 10.1016/j.virol.2005.05.002] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2005] [Revised: 04/08/2005] [Accepted: 05/04/2005] [Indexed: 11/19/2022]
Abstract
Endoproteolytic processing of the human immunodeficiency virus type 1 (HIV-1) envelope (Env) glycoproteins is an obligate part of the biosynthetic pathway that generates functional, fusion-competent Env complexes, which are then incorporated into infectious virions. We have examined the influence of cleavage on Env-specific antibody reactivity, Env incorporation into pseudovirions, and the infectivity and neutralization sensitivity of Env-pseudotyped viruses. To do so, we have used both incompletely processed wild-type (Wt) Env and engineered, cleavage-defective Env mutants. We find that there is no simple association between antibody reactivity to cell surface-expressed Env, and the ability of the same antibody to neutralize virus pseudotyped with the same Env proteins. One explanation for the absence of such an association is the diverse array of Env species present on the surface of transiently transfected cells. We also confirm that cleavage-defective mutants are antigenically different from Wt Env. These findings have implications for the use of Env binding assays as predictors of neutralizing activity, and for the development of cleavage-defective Env trimers for use as subunit immunogens.
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Affiliation(s)
- Carolina Herrera
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, 1300 York Avenue, Room W-805, New York, NY 10021, USA
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37
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Beddows S, Schülke N, Kirschner M, Barnes K, Franti M, Michael E, Ketas T, Sanders RW, Maddon PJ, Olson WC, Moore JP. Evaluating the immunogenicity of a disulfide-stabilized, cleaved, trimeric form of the envelope glycoprotein complex of human immunodeficiency virus type 1. J Virol 2005; 79:8812-27. [PMID: 15994775 PMCID: PMC1168742 DOI: 10.1128/jvi.79.14.8812-8827.2005] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) complex comprises three gp120 exterior glycoproteins each noncovalently linked to a gp41 transmembrane glycoprotein. Monomeric gp120 proteins can elicit antibodies capable of neutralizing atypically sensitive test viruses in vitro, but these antibodies are ineffective against representative primary isolates and the gp120 vaccines failed to provide protection against HIV-1 transmission in vivo. Alternative approaches to raising neutralizing antibodies are therefore being pursued. Here we report on the antibody responses generated in rabbits against a soluble, cleaved, trimeric form of HIV-1(JR-FL) Env. In this construct, the gp120 and gp41 moieties are covalently linked by an intermolecular disulfide bond (SOS gp140), and an I559P substitution has been added to stabilize gp41-gp41 interactions (SOSIP gp140). We investigated the value of DNA priming and compared the use of membrane-bound and soluble priming antigens and of repeat boosting with soluble and particulate protein antigen. Compared to monomeric gp120, SOSIP gp140 trimers elicited approximately threefold lower titers of anti-gp120 antibodies. Priming with DNA encoding a membrane-bound form of the SOS gp140 protein, followed by several immunizations with soluble SOSIP gp140 trimers, resulted in antibodies capable of neutralizing sensitive strains at high titers. A subset of these sera also neutralized, at lower titers, HIV-1(JR-FL) and some other primary isolates in pseudovirus and/or whole-virus assays. Neutralization of these viruses was immunoglobulin mediated and was predominantly caused by antibodies to gp120 epitopes, but not the V3 region.
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Affiliation(s)
- Simon Beddows
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, 1300 York Ave., Room W-805, New York, NY 10021, USA
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38
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Yuan W, Craig S, Yang X, Sodroski J. Inter-subunit disulfide bonds in soluble HIV-1 envelope glycoprotein trimers. Virology 2005; 332:369-83. [PMID: 15661168 DOI: 10.1016/j.virol.2004.11.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2004] [Revised: 09/28/2004] [Accepted: 11/11/2004] [Indexed: 11/18/2022]
Abstract
Soluble forms of the trimeric human immunodeficiency virus (HIV-1) envelope glycoproteins are important tools for structural studies and in the construction of improved immunogens. We found that a substantial fraction of soluble envelope glycoprotein trimers contain inter-subunit disulfide bonds (inter-S-S bonds) that render the trimers resistant to heat and denaturing agents. These inter-S-S bonds can be reduced without disrupting the trimers by treatment with a low concentration of beta-mercaptoethanol or DTT. Antibody mapping studies suggest that the soluble HIV-1 envelope glycoprotein trimers lacking the inter-S-S bonds exhibit a conformation closer to that of the native HIV-1 envelope glycoprotein complex. However, reducing these inter-S-S bonds had only modest effects on the inefficient elicitation of neutralizing antibodies by the soluble trimers. These studies provide guidance in improving the resemblance of tractable, soluble forms of the HIV-1 envelope glycoproteins to the native virion spikes.
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Affiliation(s)
- Wen Yuan
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Boston, MA 02115, USA
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39
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Meintjes PL, Rodrigo AG. Evolution of relative synonymous codon usage in Human Immunodeficiency Virus type-1. J Bioinform Comput Biol 2005; 3:157-68. [PMID: 15751118 DOI: 10.1142/s0219720005000953] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2004] [Revised: 06/25/2004] [Accepted: 07/10/2004] [Indexed: 11/18/2022]
Abstract
Mutation in Human Immunodeficiency Virus type-1 (HIV-1) is extremely rapid, a consequence of a low-fidelity viral reverse transcription process. The envelope gene has been shown to accumulate substitutions at a rate of approximately 1% per year and can frequently spend a long time in the host (approximately 10 years). The relative synonymous codon usage (RSCU) in HIV-1 is known to be different from that of the human host. However, by reengineering the protein coding sequences of HIV-1 to reflect the RSCU patterns observed in humans, a large increase in protein expression is observed. It is reasonable to suggest that within a host there may be a selective drive for change in the RSCU of HIV-1 towards human RSCU. To test this hypothesis we analyzed HIV-1 partial envelope sequences from eight patients sampled serially in time. For each sequence, an RSCU table was constructed. Sequences were labelled as "early" or "late" depending on whether they were sampled before or after the mid-point of the study. Using the RSCU values as descriptor variables, a Principal Components Analysis (PCA) was performed. The first three components clearly discriminated between early and late sequences. We also constructed pooled groupwise RSCU tables for early and late sequences. The viral RSCU values of each of the groups were correlated with human RSCU. If there is selection for host-adaptation in RSCU, we expect that "late" viral RSCUs would tend to be more highly correlated with human RSCU than "early" viral RSCUs. In fact, tests of significance suggest that this is the case. However, closer examination of the data revealed that the apparent trend towards human RSCU can be attributed to the homogenization of the codon usage by mutation pressure rather than host adaptation.
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Affiliation(s)
- Peter L Meintjes
- Bioinformatics Institute and Computational and Evolutionary Biology Lab, School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand.
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40
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Yang X, Kurteva S, Lee S, Sodroski J. Stoichiometry of antibody neutralization of human immunodeficiency virus type 1. J Virol 2005; 79:3500-8. [PMID: 15731244 PMCID: PMC1075697 DOI: 10.1128/jvi.79.6.3500-3508.2005] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The human immunodeficiency virus envelope glycoproteins function as trimers on the viral surface, where they are targeted by neutralizing antibodies. Different monoclonal antibodies neutralize human immunodeficiency virus type 1 (HIV-1) infectivity by binding to structurally and functionally distinct moieties on the envelope glycoprotein trimer. By measuring antibody neutralization of viruses with mixtures of neutralization-sensitive and neutralization-resistant envelope glycoproteins, we demonstrate that the HIV-1 envelope glycoprotein trimer is inactivated by the binding of a single antibody molecule. Virus neutralization requires essentially all of the functional trimers to be occupied by at least one antibody. This model applies to antibodies differing in neutralizing potency and to virus isolates with various neutralization sensitivities. Understanding these requirements for HIV-1 neutralization by antibodies will assist in establishing goals for an effective AIDS vaccine.
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Affiliation(s)
- Xinzhen Yang
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, JFB-609, 44 Binney St., Boston, MA 02115, USA.
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41
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Kang SM, Quan FS, Huang C, Guo L, Ye L, Yang C, Compans RW. Modified HIV envelope proteins with enhanced binding to neutralizing monoclonal antibodies. Virology 2005; 331:20-32. [PMID: 15582650 DOI: 10.1016/j.virol.2004.10.005] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The target for neutralizing antibodies against human immunodeficiency virus (HIV) is the trimeric Env protein on the native virion. Conserved neutralizing epitopes of receptor binding sites are located in the recessed core of the Env protein, partially masked by glycosylations and variable loops. In this study, we have investigated the effects of modifications of the HIV Env protein by glycosylation site mutations, deletions of variable loops, or combinations of both types of mutations on their protein functions and reactivities with neutralizing antibodies. Modified Env proteins were expressed in insect or mammalian cells, and their reactivity with epitope-specific broadly neutralizing monoclonal antibodies (Mabs) was determined by flow cytometry. A unique mutant designated 3G with mutations in three glycosylation motifs within the V3/C3 domains surrounding the CD4 binding site showed higher levels of binding to most broadly neutralizing Mabs (b12 and 2F5) in both insect and mammalian expression systems. Mutants with a deletion of both V1 and V2 loop domains or with a unique combination of both types of mutations also bound to most neutralizing Mabs at higher levels compared to the wild-type control. Most mutants maintained the ability to bind CD4 and to induce syncytium formation at similar or higher levels as compared to that of the wild-type Env protein, except for a mutant with a combination of variable loop deletions and deglycosylation mutations. Our study suggests that modified HIV Env proteins with reduced glycosylation in domains surrounding the CD4 binding site or variable loop-deleted mutants expose important neutralizing epitopes at higher levels than wild type and may provide novel vaccine immunogens.
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Affiliation(s)
- Sang-Moo Kang
- Department of Microbiology and Immunology, Emory University School of Medicine, 1510 Clifton Road, RRC 3086, Atlanta, GA 30322, USA.
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Pancera M, Wyatt R. Selective recognition of oligomeric HIV-1 primary isolate envelope glycoproteins by potently neutralizing ligands requires efficient precursor cleavage. Virology 2005; 332:145-56. [PMID: 15661147 DOI: 10.1016/j.virol.2004.10.042] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2004] [Revised: 08/30/2004] [Accepted: 10/26/2004] [Indexed: 11/29/2022]
Abstract
A critical component of an effective HIV vaccine will be the induction of broadly neutralizing antibodies. Comprising the HIV spike, the exterior envelope glycoprotein gp120 and the transmembrane glycoprotein gp41 mediate receptor binding, viral entry, and are the targets for neutralizing antibodies. The gp120 and gp41 glycoproteins are derived from the gp160 precursor glycoprotein and following gp160 glycosylation, oligomerization and cleavage in the endoplasmic reticulum and Golgi, remain as non-covalently associated trimers of heterodimers. Previously, using cell-surface envelope glycoproteins derived from infection of a laboratory-adapted HIV-1 strain, a correlation had been established between the binding of gp120-directed antibodies to the viral glycoprotein and the ability of the antibodies to neutralize laboratory-adapted isolates. However, this has been more difficult to demonstrate for glycoproteins derived from primary patient isolates. Here, using a FACS-based method, we report that only gp120-directed neutralizing antibodies and the neutralizing ligand soluble CD4 efficiently bind to glycoproteins derived from the JR-FL primary isolate provided that the gp160 precursor protein is efficiently cleaved. Precursor cleavage was demonstrated by cell-surface biotinylation and Western blotting. In stark contrast, both non-neutralizing and neutralizing antibodies bind non-cleaved envelope glycoproteins from JR-FL and YU2 isolates. These data imply that significant changes in Env spike structure are dependent upon precursor gp160 cleavage and are consistent with a restricted-binding-to-Env model of neutralization. The data also have implications in regards to the use and design of non-cleaved envelope glycoprotein trimeric immunogens as a means to selectively and preferentially present neutralizing epitopes to the host immune system.
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Affiliation(s)
- Marie Pancera
- Structural Virology Section, Vaccine Research Center, NIAID, National Institutes of Health, 40 Convent Drive, Building 40, Room 4512, Bethesda, MD 20892, USA
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Si Z, Madani N, Cox JM, Chruma JJ, Klein JC, Schön A, Phan N, Wang L, Biorn AC, Cocklin S, Chaiken I, Freire E, Smith AB, Sodroski JG. Small-molecule inhibitors of HIV-1 entry block receptor-induced conformational changes in the viral envelope glycoproteins. Proc Natl Acad Sci U S A 2004; 101:5036-41. [PMID: 15051887 PMCID: PMC387369 DOI: 10.1073/pnas.0307953101] [Citation(s) in RCA: 222] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
When interacting with the CD4 receptor, the HIV gp120 envelope glycoprotein undergoes conformational changes that allow binding to the chemokine receptor. Receptor binding is proposed to lead to conformational changes in the gp41 transmembrane envelope glycoprotein involving the creation and/or exposure of a coiled coil consisting of three heptad repeat (HR) sequences. The subsequent interaction of the HR2 region of gp41 with this coiled coil results in the assembly of a six-helix bundle that promotes the fusion of the viral and target cell membranes. Here we show that CD4 binding to gp120 induces the formation and/or exposure of the gp41 HR1 coiled coil in a process that does not involve gp120 shedding and that depends on the proteolytic maturation of the gp160 envelope glycoprotein precursor. Importantly, BMS-806 and related HIV-1 entry inhibitors bind gp120 and block the CD4 induction of HR1 exposure without significantly affecting CD4 binding. Moreover, these compounds do not disrupt gp120-chemokine receptor binding or the HR1-HR2 interaction within gp41. These studies thus define a receptor-induced conformational rearrangement of gp120-gp41 that is important for both CD4-dependent and CD4-independent HIV-1 entry and is susceptible to inhibition by low-molecular-weight compounds.
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Affiliation(s)
- Zhihai Si
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Boston, MA 02115, USA
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44
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Si Z, Gorry P, Babcock G, Owens CM, Cayabyab M, Phan N, Sodroski J. Envelope glycoprotein determinants of increased entry in a pathogenic simian-human immunodeficiency virus (SHIV-HXBc2P 3.2) passaged in monkeys. AIDS Res Hum Retroviruses 2004; 20:163-73. [PMID: 15018704 DOI: 10.1089/088922204773004888] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Passage of a nonpathogenic simian-human immunodeficiency virus (SHIV-HXBc2) in monkeys resulted in changes in the viral envelope glycoproteins that are responsible for a dramatic increase in replication and pathogenicity in vivo. Here, we show that the envelope glycoproteins of the pathogenic SHIV-HXBc2P 3.2 mediate virus entry into rhesus monkey peripheral blood mononuclear cells (PBMC) more efficiently than the parental SHIV-HXBc2 envelope glycoproteins, and study the basis for this increase. Both parental and pathogenic SHIVs exclusively use CXCR4 as a coreceptor. The determinants of the increased entry associated with the SHIV-HXBc2P 3.2 envelope glycoproteins are located in both the gp120 and gp41 subunits. Changes in the gp120 V3 variable loop specify a decreased sensitivity to SDF-1, consistent with an increase in the affinity of the HXBc2P 3.2 gp120 glycoprotein for CXCR4. Thus, multiple changes in the gp120 variable loops and the gp41 ectodomain of a pathogenic SHIV cooperate to allow enhanced replicative capacity, which in part results from increased chemokine receptor binding.
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Affiliation(s)
- Zhihai Si
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Department of Pathology, Division of AIDS, Harvard Medical School, Boston, Massachusetts 02115, USA
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