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Rao PG, Lambert GS, Upadhyay C. Broadly neutralizing antibody epitopes on HIV-1 particles are exposed after virus interaction with host cells. J Virol 2023; 97:e0071023. [PMID: 37681958 PMCID: PMC10537810 DOI: 10.1128/jvi.00710-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 07/07/2023] [Indexed: 09/09/2023] Open
Abstract
The envelope (Env) glycoproteins on HIV-1 virions are the sole target of broadly neutralizing antibodies (bNAbs) and the focus of vaccines. However, many cross-reactive conserved epitopes are often occluded on virus particles, contributing to the evasion of humoral immunity. This study aimed to identify the Env epitopes that are exposed/occluded on HIV-1 particles and to investigate the mechanisms contributing to their masking. Using a flow cytometry-based assay, three HIV-1 isolates, and a panel of antibodies, we show that only select epitopes, including V2i, the gp120-g41 interface, and gp41-MPER, are accessible on HIV-1 particles, while V3, V2q, and select CD4bs epitopes are masked. These epitopes become accessible after allosteric conformational changes are induced by the pre-binding of select Abs, prompting us to test if similar conformational changes are required for these Abs to exhibit their neutralization capability. We tested HIV-1 neutralization where the virus-mAb mix was pre-incubated/not pre-incubated for 1 hour prior to adding the target cells. Similar levels of neutralization were observed under both assay conditions, suggesting that the interaction between virus and target cells sensitizes the virions for neutralization via bNAbs. We further show that lectin-glycan interactions can also expose these epitopes. However, this effect is dependent on the lectin specificity. Given that, bNAbs are ideal for providing sterilizing immunity and are the goal of current HIV-1 vaccine efforts, these data offer insight on how HIV-1 may occlude these vulnerable epitopes from the host immune response. In addition, the findings can guide the formulation of effective antibody combinations for therapeutic use. IMPORTANCE The human immunodeficiency virus (HIV-1) envelope (Env) glycoprotein mediates viral entry and is the sole target of neutralizing antibodies. Our data suggest that antibody epitopes including V2q (e.g., PG9, PGT145), CD4bs (e.g., VRC01, 3BNC117), and V3 (2219, 2557) are masked on HIV-1 particles. The PG9 and 2219 epitopes became accessible for binding after conformational unmasking was induced by the pre-binding of select mAbs. Attempts to understand the masking mechanism led to the revelation that interaction between virus and host cells is needed to sensitize the virions for neutralization by broadly neutralizing antibodies (bNAbs). These data provide insight on how bNAbs may gain access to these occluded epitopes to exert their neutralization effects and block HIV-1 infection. These findings have important implications for the way we evaluate the neutralizing efficacy of antibodies and can potentially guide vaccine design.
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Affiliation(s)
- Priyanka Gadam Rao
- Division of Infectious Disease, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Gregory S. Lambert
- Division of Infectious Disease, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Chitra Upadhyay
- Division of Infectious Disease, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA
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2
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Rao PG, Lambert GS, Upadhyay C. Broadly Neutralizing Antibody Epitopes on HIV-1 Particles are exposed after Virus Interaction with Host Cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.20.524996. [PMID: 36711466 PMCID: PMC9882293 DOI: 10.1101/2023.01.20.524996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The envelope glycoproteins (Env) on HIV-1 virions are the sole target of broadly neutralizing antibodies (bNAb) and the focus of vaccines. However, many cross-reactive conserved epitopes are often occluded on virus particles, contributing to the evasion of humoral immunity. This study aimed to identify the Env epitopes that are exposed/occluded on HIV-1 particles and to investigate the mechanisms contributing to their masking. Using a flow cytometry-based assay, three HIV-1 isolates, and a panel of antibodies, we show that only select epitopes including V2i, gp120-g41 interface, and gp41-MPER are accessible on HIV-1 particles, while V3, V2q, and select CD4bs epitopes are masked. These epitopes become accessible after allosteric conformational changes are induced by pre-binding of select Abs, prompting us to test if similar conformational changes are required for these Abs to exhibit their neutralization capability. We tested HIV-1 neutralization where virus-mAb mix was pre-incubated/not pre-incubated for one hour prior to adding the target cells. Similar levels of neutralization were observed under both assay conditions, suggesting that the interaction between virus and target cells sensitizes the virions for neutralization via bNAbs. We further show that lectin-glycan interactions can also expose these epitopes. However, this effect is dependent on the lectin specificity. Given that, bNAbs are the ideal for providing sterilizing immunity and are the goal of current HIV-1 vaccine efforts, these data offer insight on how HIV-1 may occlude these vulnerable epitopes from the host immune response. In addition, the findings can guide the formulation of effective antibody combinations for therapeutic use.
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3
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Upadhyay C, Rao PG, Feyznezhad R. Dual Role of HIV-1 Envelope Signal Peptide in Immune Evasion. Viruses 2022; 14:v14040808. [PMID: 35458538 PMCID: PMC9030904 DOI: 10.3390/v14040808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 04/08/2022] [Accepted: 04/11/2022] [Indexed: 12/10/2022] Open
Abstract
HIV-1 Env signal peptide (SP) is an important contributor to Env functions. Env is generated from Vpu/Env encoded bicistronic mRNA such that the 5′ end of Env-N-terminus, that encodes for Env-SP overlaps with 3′ end of Vpu. Env SP displays high sequence diversity, which translates into high variability in Vpu sequence. This study aimed to understand the effect of sequence polymorphism in the Vpu-Env overlapping region (VEOR) on the functions of two vital viral proteins: Vpu and Env. We used infectious molecular clone pNL4.3-CMU06 and swapped its SP (or VEOR) with that from other HIV-1 isolates. Swapping VEOR did not affect virus production in the absence of tetherin however, presence of tetherin significantly altered the release of virus progeny. VEOR also altered Vpu’s ability to downregulate CD4 and tetherin. We next tested the effect of these swaps on Env functions. Analyzing the binding of monoclonal antibodies to membrane embedded Env revealed changes in the antigenic landscape of swapped Envs. These swaps affected the oligosaccharide composition of Env-N-glycans as shown by changes in DC-SIGN-mediated virus transmission. Our study suggests that genetic diversity in VEOR plays an important role in the differential pathogenesis and also assist in immune evasion by altering Env epitope exposure.
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4
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Walker LM, Shiakolas AR, Venkat R, Liu ZA, Wall S, Raju N, Pilewski KA, Setliff I, Murji AA, Gillespie R, Makoah NA, Kanekiyo M, Connors M, Morris L, Georgiev IS. High-Throughput B Cell Epitope Determination by Next-Generation Sequencing. Front Immunol 2022; 13:855772. [PMID: 35401559 PMCID: PMC8984479 DOI: 10.3389/fimmu.2022.855772] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Accepted: 02/14/2022] [Indexed: 01/12/2023] Open
Abstract
Development of novel technologies for the discovery of human monoclonal antibodies has proven invaluable in the fight against infectious diseases. Among the diverse antibody repertoires elicited by infection or vaccination, often only rare antibodies targeting specific epitopes of interest are of potential therapeutic value. Current antibody discovery efforts are capable of identifying B cells specific for a given antigen; however, epitope specificity information is usually only obtained after subsequent monoclonal antibody production and characterization. Here we describe LIBRA-seq with epitope mapping, a next-generation sequencing technology that enables residue-level epitope determination for thousands of single B cells simultaneously. By utilizing an antigen panel of point mutants within the HIV-1 Env glycoprotein, we identified and confirmed antibodies targeting multiple sites of vulnerability on Env, including the CD4-binding site and the V3-glycan site. LIBRA-seq with epitope mapping is an efficient tool for high-throughput identification of antibodies against epitopes of interest on a given antigen target.
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Affiliation(s)
- Lauren M. Walker
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, United States
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Andrea R. Shiakolas
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, United States
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Rohit Venkat
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Zhaojing Ariel Liu
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Steven Wall
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, United States
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Nagarajan Raju
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, United States
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Kelsey A. Pilewski
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, United States
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Ian Setliff
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Amyn A. Murji
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Rebecca Gillespie
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Bethesda, MD, United States
| | - Nigel A. Makoah
- Division of Virology, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa
- National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
| | - Masaru Kanekiyo
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Bethesda, MD, United States
| | - Mark Connors
- National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Bethesda, MD, United States
| | - Lynn Morris
- National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Antibody Immunity Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu-Natal, Durban, South Africa
| | - Ivelin S. Georgiev
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, United States
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, United States
- Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN, United States
- Center for Structural Biology, Vanderbilt University, Nashville, TN, United States
- Program in Computational Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States
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5
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Hioe CE, Li G, Liu X, Tsahouridis O, He X, Funaki M, Klingler J, Tang AF, Feyznezhad R, Heindel DW, Wang XH, Spencer DA, Hu G, Satija N, Prévost J, Finzi A, Hessell AJ, Wang S, Lu S, Chen BK, Zolla-Pazner S, Upadhyay C, Alvarez R, Su L. Non-neutralizing antibodies targeting the immunogenic regions of HIV-1 envelope reduce mucosal infection and virus burden in humanized mice. PLoS Pathog 2022; 18:e1010183. [PMID: 34986207 PMCID: PMC8765624 DOI: 10.1371/journal.ppat.1010183] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 01/18/2022] [Accepted: 12/09/2021] [Indexed: 02/07/2023] Open
Abstract
Antibodies are principal immune components elicited by vaccines to induce protection from microbial pathogens. In the Thai RV144 HIV-1 vaccine trial, vaccine efficacy was 31% and the sole primary correlate of reduced risk was shown to be vigorous antibody response targeting the V1V2 region of HIV-1 envelope. Antibodies against V3 also were inversely correlated with infection risk in subsets of vaccinees. Antibodies recognizing these regions, however, do not exhibit potent neutralizing activity. Therefore, we examined the antiviral potential of poorly neutralizing monoclonal antibodies (mAbs) against immunodominant V1V2 and V3 sites by passive administration of human mAbs to humanized mice engrafted with CD34+ hematopoietic stem cells, followed by mucosal challenge with an HIV-1 infectious molecular clone expressing the envelope of a tier 2 resistant HIV-1 strain. Treatment with anti-V1V2 mAb 2158 or anti-V3 mAb 2219 did not prevent infection, but V3 mAb 2219 displayed a superior potency compared to V1V2 mAb 2158 in reducing virus burden. While these mAbs had no or weak neutralizing activity and elicited undetectable levels of antibody-dependent cellular cytotoxicity (ADCC), V3 mAb 2219 displayed a greater capacity to bind virus- and cell-associated HIV-1 envelope and to mediate antibody-dependent cellular phagocytosis (ADCP) and C1q complement binding as compared to V1V2 mAb 2158. Mutations in the Fc region of 2219 diminished these effector activities in vitro and lessened virus control in humanized mice. These results demonstrate the importance of Fc functions other than ADCC for antibodies without potent neutralizing activity.
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Affiliation(s)
- Catarina E. Hioe
- Division of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- James J. Peters VA Medical Center, Bronx, New York, New York, United States of America
| | - Guangming Li
- Laboratory of Viral Pathogenesis and Immunotherapy, Division of Virology, Pathogenesis, and Cancer, Institute of Human Virology, Department of Pharmacology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Lineberger Comprehensive Cancer Center, Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Xiaomei Liu
- Division of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Ourania Tsahouridis
- Lineberger Comprehensive Cancer Center, Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Xiuting He
- Laboratory of Viral Pathogenesis and Immunotherapy, Division of Virology, Pathogenesis, and Cancer, Institute of Human Virology, Department of Pharmacology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Masaya Funaki
- Laboratory of Viral Pathogenesis and Immunotherapy, Division of Virology, Pathogenesis, and Cancer, Institute of Human Virology, Department of Pharmacology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Jéromine Klingler
- Division of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- James J. Peters VA Medical Center, Bronx, New York, New York, United States of America
| | - Alex F. Tang
- Division of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- School of Medicine, University of California, San Francisco, California, United States of America
| | - Roya Feyznezhad
- Division of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Daniel W. Heindel
- Division of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Xiao-Hong Wang
- VA New York Harbor Healthcare System–Manhattan, New York, New York, United States of America
| | - David A. Spencer
- Division of Pathobiology & Immunology, Oregon Health & Science University, Oregon National Primate Research Center, Beaverton, Oregon, United States of America
| | - Guangnan Hu
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Namita Satija
- Division of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Jérémie Prévost
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Montreal, Quebec, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Quebec, Canada
| | - Andrés Finzi
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Montreal, Quebec, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Quebec, Canada
| | - Ann J. Hessell
- Division of Pathobiology & Immunology, Oregon Health & Science University, Oregon National Primate Research Center, Beaverton, Oregon, United States of America
| | - Shixia Wang
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Shan Lu
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Benjamin K. Chen
- Division of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Susan Zolla-Pazner
- Division of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Chitra Upadhyay
- Division of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Raymond Alvarez
- Division of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Lishan Su
- Laboratory of Viral Pathogenesis and Immunotherapy, Division of Virology, Pathogenesis, and Cancer, Institute of Human Virology, Department of Pharmacology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Lineberger Comprehensive Cancer Center, Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, United States of America
- Laboratory of Viral Pathogenesis and Immunotherapy, Division of Virology, Pathogenesis and Cancer, Institute of Human Virology, Departments of Pharmacology and Microbiology & Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
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6
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Friedrich N, Stiegeler E, Glögl M, Lemmin T, Hansen S, Kadelka C, Wu Y, Ernst P, Maliqi L, Foulkes C, Morin M, Eroglu M, Liechti T, Ivan B, Reinberg T, Schaefer JV, Karakus U, Ursprung S, Mann A, Rusert P, Kouyos RD, Robinson JA, Günthard HF, Plückthun A, Trkola A. Distinct conformations of the HIV-1 V3 loop crown are targetable for broad neutralization. Nat Commun 2021; 12:6705. [PMID: 34795280 PMCID: PMC8602657 DOI: 10.1038/s41467-021-27075-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 11/03/2021] [Indexed: 12/14/2022] Open
Abstract
The V3 loop of the HIV-1 envelope (Env) protein elicits a vigorous, but largely non-neutralizing antibody response directed to the V3-crown, whereas rare broadly neutralizing antibodies (bnAbs) target the V3-base. Challenging this view, we present V3-crown directed broadly neutralizing Designed Ankyrin Repeat Proteins (bnDs) matching the breadth of V3-base bnAbs. While most bnAbs target prefusion Env, V3-crown bnDs bind open Env conformations triggered by CD4 engagement. BnDs achieve breadth by focusing on highly conserved residues that are accessible in two distinct V3 conformations, one of which resembles CCR5-bound V3. We further show that these V3-crown conformations can, in principle, be attacked by antibodies. Supporting this conclusion, analysis of antibody binding activity in the Swiss 4.5 K HIV-1 cohort (n = 4,281) revealed a co-evolution of V3-crown reactivities and neutralization breadth. Our results indicate a role of V3-crown responses and its conformational preferences in bnAb development to be considered in preventive and therapeutic approaches.
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Affiliation(s)
- Nikolas Friedrich
- grid.7400.30000 0004 1937 0650Institute of Medical Virology, University of Zurich (UZH), Zurich, Switzerland
| | - Emanuel Stiegeler
- grid.7400.30000 0004 1937 0650Institute of Medical Virology, University of Zurich (UZH), Zurich, Switzerland ,grid.424277.0Present Address: Roche Diagnostics GmbH, Nonnenwald 2, 82377 Penzberg, Deutschland
| | - Matthias Glögl
- grid.7400.30000 0004 1937 0650Institute of Medical Virology, University of Zurich (UZH), Zurich, Switzerland
| | - Thomas Lemmin
- grid.7400.30000 0004 1937 0650Institute of Medical Virology, University of Zurich (UZH), Zurich, Switzerland ,grid.5801.c0000 0001 2156 2780Department of Computer Science, ETH Zurich, Zurich, Switzerland ,grid.29078.340000 0001 2203 2861Present Address: Euler Institute, Faculty of Biomedicine, Università della Svizzera italiana (USI), Lugano, Switzerland
| | - Simon Hansen
- grid.7400.30000 0004 1937 0650Department of Biochemistry, University of Zurich (UZH), Zurich, Switzerland ,Present Address: NGM Bio, 333 Oysterpoint Blvd, South San Francisco, CA 94080 USA
| | - Claus Kadelka
- grid.34421.300000 0004 1936 7312Department of Mathematics, Iowa State University, Ames, IA USA
| | - Yufan Wu
- grid.7400.30000 0004 1937 0650Department of Biochemistry, University of Zurich (UZH), Zurich, Switzerland ,Present Address: Innovent Biologics Inc, 168 Dongping Street, Suzhou Industrial Park, 215123 China
| | - Patrick Ernst
- grid.7400.30000 0004 1937 0650Department of Biochemistry, University of Zurich (UZH), Zurich, Switzerland ,grid.7400.30000 0004 1937 0650Present Address: Office Research and Teaching, Medical Faculty, University of Zurich, Zurich, Switzerland
| | - Liridona Maliqi
- grid.7400.30000 0004 1937 0650Institute of Medical Virology, University of Zurich (UZH), Zurich, Switzerland
| | - Caio Foulkes
- grid.7400.30000 0004 1937 0650Institute of Medical Virology, University of Zurich (UZH), Zurich, Switzerland
| | - Mylène Morin
- grid.7400.30000 0004 1937 0650Department of Chemistry, University of Zurich (UZH), Zurich, Switzerland ,Present Address: BeiGene Switzerland GmbH, Aeschengraben 27, 4051 Basel, Switzerland
| | - Mustafa Eroglu
- grid.7400.30000 0004 1937 0650Institute of Medical Virology, University of Zurich (UZH), Zurich, Switzerland ,Present Address: Janssen Vaccines AG, Rehhagstrasse 79, 3018 Bern, Switzerland
| | - Thomas Liechti
- grid.7400.30000 0004 1937 0650Institute of Medical Virology, University of Zurich (UZH), Zurich, Switzerland ,grid.419681.30000 0001 2164 9667Present Address: ImmunoTechnology Section, Vaccine Research Center, NIAID, NIH, Bethesda, MD USA
| | - Branislav Ivan
- grid.7400.30000 0004 1937 0650Institute of Medical Virology, University of Zurich (UZH), Zurich, Switzerland ,grid.410567.1Present Address: Laboratory Medicine, Division of Clinical Chemistry, University Hospital Basel, Basel, Switzerland
| | - Thomas Reinberg
- grid.7400.30000 0004 1937 0650Department of Biochemistry, University of Zurich (UZH), Zurich, Switzerland
| | - Jonas V. Schaefer
- grid.7400.30000 0004 1937 0650Department of Biochemistry, University of Zurich (UZH), Zurich, Switzerland ,grid.419481.10000 0001 1515 9979Present Address: Novartis Institutes for BioMedical Research, Chemical Biology & Therapeutics (CBT), Novartis Pharma AG, Virchow 16, 4056 Basel, Switzerland
| | - Umut Karakus
- grid.7400.30000 0004 1937 0650Institute of Medical Virology, University of Zurich (UZH), Zurich, Switzerland
| | - Stephan Ursprung
- grid.7400.30000 0004 1937 0650Institute of Medical Virology, University of Zurich (UZH), Zurich, Switzerland ,grid.5335.00000000121885934Present Address: University of Cambridge School of Clinical Medicine, Department of Radiology, Cambridge, CB2 0QQ UK
| | - Axel Mann
- grid.7400.30000 0004 1937 0650Institute of Medical Virology, University of Zurich (UZH), Zurich, Switzerland ,Present Address: Roche Innovation Center Zurich, Roche Pharmaceutical Research and Early Development (pRED), Wagistrasse 10, 8952 Schlieren, Switzerland
| | - Peter Rusert
- grid.7400.30000 0004 1937 0650Institute of Medical Virology, University of Zurich (UZH), Zurich, Switzerland
| | - Roger D. Kouyos
- grid.7400.30000 0004 1937 0650Institute of Medical Virology, University of Zurich (UZH), Zurich, Switzerland ,grid.412004.30000 0004 0478 9977Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich (USZ), Zurich, Switzerland
| | - John A. Robinson
- grid.7400.30000 0004 1937 0650Department of Chemistry, University of Zurich (UZH), Zurich, Switzerland
| | - Huldrych F. Günthard
- grid.7400.30000 0004 1937 0650Institute of Medical Virology, University of Zurich (UZH), Zurich, Switzerland ,grid.412004.30000 0004 0478 9977Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich (USZ), Zurich, Switzerland
| | - Andreas Plückthun
- grid.7400.30000 0004 1937 0650Department of Biochemistry, University of Zurich (UZH), Zurich, Switzerland
| | - Alexandra Trkola
- Institute of Medical Virology, University of Zurich (UZH), Zurich, Switzerland.
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7
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Global Variability of V3 Loop Tetrapeptide Motif: a Concern for HIV-1 Neutralizing Antibodies-based Vaccine Design and Antiretroviral Therapy. JOURNAL OF MEDICAL MICROBIOLOGY AND INFECTIOUS DISEASES 2021. [DOI: 10.52547/jommid.9.3.108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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8
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Signal peptide of HIV-1 envelope modulates glycosylation impacting exposure of V1V2 and other epitopes. PLoS Pathog 2020; 16:e1009185. [PMID: 33370382 PMCID: PMC7793277 DOI: 10.1371/journal.ppat.1009185] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 01/08/2021] [Accepted: 11/24/2020] [Indexed: 11/19/2022] Open
Abstract
HIV-1 envelope (Env) is a trimer of gp120-gp41 heterodimers, synthesized from a precursor gp160 that contains an ER-targeting signal peptide (SP) at its amino-terminus. Each trimer is swathed by ~90 N-linked glycans, comprising complex-type and oligomannose-type glycans, which play an important role in determining virus sensitivity to neutralizing antibodies. We previously examined the effects of single point SP mutations on Env properties and functions. Here, we aimed to understand the impact of the SP diversity on glycosylation of virus-derived Env and virus neutralization by swapping SPs. Analyses of site-specific glycans revealed that SP swapping altered Env glycan content and occupancy on multiple N-linked glycosites, including conserved N156 and N160 glycans in the V1V2 region at the Env trimer apex and N88 at the trimer base. Virus neutralization was also affected, especially by antibodies against V1V2, V3, and gp41. Likewise, SP swaps affected the recognition of soluble and cell-associated Env by antibodies targeting distinct V1V2 configurations, V3 crown, and gp41 epitopes. These data highlight the contribution of SP sequence diversity in shaping the Env glycan content and its impact on the configuration and accessibility of V1V2 and other Env epitopes. HIV-1 Env glycoprotein is produced by a precursor gp160 that has a signal peptide at its N-terminus. The SP is highly diverse among the HIV-1 isolates. This study presents site-specific analyses of N-linked glycosylation on HIV-1 envelope glycoproteins from infectious viruses produced with different envelope signal peptides. We show that signal peptide swapping alters the envelope glycan shield, including the conserved N156 and N160 glycans located in the V1V2 region on the trimer apex, to impact Env recognition and virus neutralization by antibodies. The data offer crucial insights into the role of signal peptide in the interplay between HIV-1 and antibodies and its potential utility to control Env glycosylation in the development of Env-based HIV-1 vaccine.
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9
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Bontempo A, Garcia MM, Rivera N, Cayabyab MJ. A Systematic Approach to HIV-1 Vaccine Immunogen Selection. AIDS Res Hum Retroviruses 2020; 36:762-770. [PMID: 32056466 DOI: 10.1089/aid.2019.0239] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
A tremendous loss of financial and human resources from seven large-scale HIV vaccine efficacy trials suggest a need for a systematic approach to vaccine selection. We conducted a systematic analysis of three important envelope glycoprotein (Env) vaccine candidates: BG505 SOSIP.664, 1086.C gp140, and 1086.C gp120 to determine the most promising by comparing their structure and antigenicity. We found that the BG505 SOSIP trimer and 1086.C gp140 clearly outperformed the 1086.C gp120 monomer. BG505 SOSIP.664 bound the strongest to the most potent and broadest broadly neutralizing antibodies (bnAbs) PG9, PGT145, VRC01, and PGT121. Of interest, although BG505 SOSIP.664 did not bind to the CH58 mAb, 1086.C gp140 bound strongly to this mAb, which belongs to a class of non-neutralizing antibodies that may be protective based on correlates of protection studies of the RV144 HIV vaccine trial. The 1086.C gp120 monomer was the least antigenic of the three vaccine immunogens, binding the weakest to bnAbs and CH58 mAb. Taken together, the evidence provided here combined with previous preclinical immunogenicity and efficacy data strongly argue that the BG505 SOSIP.664 trimer and 1086.C gp140 are likely to be better vaccine immunogens than the monomeric 1086.C gp120, which was just recently tested and shown to be nonefficacious in a phase IIb/III trial. Thus, to best utilize our financial and valuable human resources, we propose a systematic approach by not only comparing structure and antigenicity, but also immunogenicity and efficacy of Env vaccine candidates in the preclinical phase to the selection of only the most promising vaccine candidates for clinical testing.
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Affiliation(s)
- Alexander Bontempo
- Department of Immunology and Infectious Diseases, Forsyth Institute, Cambridge, Massachusetts, USA
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Maria M. Garcia
- Department of Immunology and Infectious Diseases, Forsyth Institute, Cambridge, Massachusetts, USA
| | - Naylene Rivera
- Department of Immunology and Infectious Diseases, Forsyth Institute, Cambridge, Massachusetts, USA
| | - Mark J. Cayabyab
- Department of Immunology and Infectious Diseases, Forsyth Institute, Cambridge, Massachusetts, USA
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10
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Chuang GY, Lai YT, Boyington JC, Cheng C, Geng H, Narpala S, Rawi R, Schmidt SD, Tsybovsky Y, Verardi R, Xu K, Yang Y, Zhang B, Chambers M, Changela A, Corrigan AR, Kong R, Olia AS, Ou L, Sarfo EK, Wang S, Wu W, Doria-Rose NA, McDermott AB, Mascola JR, Kwong PD. Development of a 3Mut-Apex-Stabilized Envelope Trimer That Expands HIV-1 Neutralization Breadth When Used To Boost Fusion Peptide-Directed Vaccine-Elicited Responses. J Virol 2020; 94:e00074-20. [PMID: 32295908 PMCID: PMC7307166 DOI: 10.1128/jvi.00074-20] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 03/31/2020] [Indexed: 01/21/2023] Open
Abstract
HIV-1 envelope (Env) trimers, stabilized in a prefusion-closed conformation, can elicit humoral responses capable of neutralizing HIV-1 strains closely matched in sequence to the immunizing strain. One strategy to increase elicited neutralization breadth involves vaccine priming of immune responses against a target site of vulnerability, followed by vaccine boosting of these responses with prefusion-closed Env trimers. This strategy has succeeded at the fusion peptide (FP) site of vulnerability in eliciting cross-clade neutralizing responses in standard vaccine-test animals. However, the breadth and potency of the elicited responses have been less than optimal. Here, we identify three mutations (3mut), Met302, Leu320, and Pro329, that stabilize the apex of the Env trimer in a prefusion-closed conformation and show antigenically, structurally, and immunogenically that combining 3mut with other approaches (e.g., repair and stabilize and glycine-helix breaking) yields well-behaved clade C-Env trimers capable of boosting the breadth of FP-directed responses. Crystal structures of these trimers confirmed prefusion-closed apexes stabilized by hydrophobic patches contributed by Met302 and Leu320, with Pro329 assuming canonically restricted dihedral angles. We substituted the N-terminal eight residues of FP (FP8, residues 512 to 519) of these trimers with the second most prevalent FP8 sequence (FP8v2, AVGLGAVF) and observed a 3mut-stabilized consensus clade C-Env trimer with FP8v2 to boost the breadth elicited in guinea pigs of FP-directed responses induced by immunogens containing the most prevalent FP8 sequence (FP8v1, AVGIGAVF). Overall, 3mut can stabilize the Env trimer apex, and the resultant apex-stabilized Env trimers can be used to expand the neutralization breadth elicited against the FP site of vulnerability.IMPORTANCE A major hurdle to the development of an effective HIV-1 vaccine is the elicitation of serum responses capable of neutralizing circulating strains of HIV, which are extraordinarily diverse in sequence and often highly neutralization resistant. Recently, we showed how sera with 20 to 30% neutralization breadth could, nevertheless, be elicited in standard vaccine test animals by priming with the most prevalent N-terminal 8 residues of the HIV-1 fusion peptide (FP8), followed by boosting with a stabilized BG505-envelope (Env) trimer. Here, we show that subsequent boosting with a 3mut-apex-stabilized consensus C-Env trimer, modified to have the second most prevalent FP8 sequence, elicits higher neutralization breadth than that induced by continued boosting with the stabilized BG505-Env trimer. With increased neutralizing breadth elicited by boosting with a heterologous trimer containing the second most prevalent FP8 sequence, the fusion peptide-directed immune-focusing approach moves a step closer toward realizing an effective HIV-1 vaccine regimen.
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Affiliation(s)
- Gwo-Yu Chuang
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Yen-Ting Lai
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Jeffrey C Boyington
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Cheng Cheng
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Hui Geng
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Sandeep Narpala
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Reda Rawi
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Stephen D Schmidt
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Yaroslav Tsybovsky
- Electron Microscopy Laboratory, Cancer Research Technology Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
| | - Raffaello Verardi
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Kai Xu
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Yongping Yang
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Baoshan Zhang
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Michael Chambers
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Anita Changela
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Angela R Corrigan
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Rui Kong
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Adam S Olia
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Li Ou
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Edward K Sarfo
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Shuishu Wang
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Winston Wu
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Nicole A Doria-Rose
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Adrian B McDermott
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - John R Mascola
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Peter D Kwong
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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11
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Doepker LE, Simonich CA, Ralph D, Shipley MM, Garrett M, Gobillot T, Vigdorovich V, Sather DN, Nduati R, Matsen FA, Overbaugh JM. Diversity and Function of Maternal HIV-1-Specific Antibodies at the Time of Vertical Transmission. J Virol 2020; 94:e01594-19. [PMID: 32075936 PMCID: PMC7163126 DOI: 10.1128/jvi.01594-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 02/08/2020] [Indexed: 12/21/2022] Open
Abstract
Infants of HIV-positive mothers can acquire HIV infection by various routes, but even in the absence of antiviral treatment, the majority of these infants do not become infected. There is evidence that maternal antibodies provide some protection from infection, but gestational maternal antibodies have not yet been characterized in detail. One of the most studied vertically infected infants is BG505, as the virus from this infant yielded an Envelope protein that was successfully developed as a stable trimer. Here, we isolated and characterized 39 HIV-specific neutralizing monoclonal antibodies (nAbs) from MG505, the mother of BG505, at a time point just prior to vertical transmission. These nAbs belonged to 21 clonal families and employed a variety of VH genes. Many were specific for the HIV-1 Env V3 loop, and this V3 specificity correlated with measurable antibody-dependent cellular cytotoxicity (ADCC) activity. The isolated nAbs did not recapitulate the full breadth of heterologous or autologous virus neutralization by contemporaneous plasma. Notably, we found that the V3-targeting nAb families neutralized one particular maternal Env variant, even though all tested variants had low V3 sequence diversity and were measurably bound by these nAbs. None of the nAbs neutralized BG505 transmitted virus. Furthermore, the MG505 nAb families were found at relatively low frequencies within the maternal B cell repertoire; all were less than 0.25% of total IgG sequences. Our findings illustrate an example of the diversity of HIV-1 nAbs within one mother, cumulatively resulting in a collection of antibody specificities that can contribute to the transmission bottleneck.IMPORTANCE Mother-to-child-transmission of HIV-1 offers a unique setting in which maternal antibodies both within the mother and passively transferred to the infant are present at the time of viral exposure. Untreated HIV-exposed human infants are infected at a rate of 30 to 40%, meaning that some infants do not get infected despite continued exposure to virus. Since the potential of HIV-specific immune responses to provide protection against HIV is a central goal of HIV vaccine design, understanding the nature of maternal antibodies may provide insights into immune mechanisms of protection. In this study, we isolated and characterized HIV-specific antibodies from the mother of an infant whose transmitted virus has been well studied.
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Affiliation(s)
- Laura E Doepker
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Cassandra A Simonich
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
- Medical Scientist Training Program, University of Washington, Seattle, Washington, USA
| | - Duncan Ralph
- Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Mackenzie M Shipley
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Meghan Garrett
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, Washington, USA
| | - Theodore Gobillot
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
- Medical Scientist Training Program, University of Washington, Seattle, Washington, USA
| | - Vladimir Vigdorovich
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - D Noah Sather
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA
- Department of Global Health, University of Washington, Seattle, Washington, USA
| | - Ruth Nduati
- Department of Pediatrics and Child Health, University of Nairobi, Nairobi, Kenya
| | - Frederick A Matsen
- Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Julie M Overbaugh
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
- Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
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12
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Neutralization-guided design of HIV-1 envelope trimers with high affinity for the unmutated common ancestor of CH235 lineage CD4bs broadly neutralizing antibodies. PLoS Pathog 2019; 15:e1008026. [PMID: 31527908 PMCID: PMC6764681 DOI: 10.1371/journal.ppat.1008026] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 09/27/2019] [Accepted: 08/12/2019] [Indexed: 11/19/2022] Open
Abstract
The CD4 binding site (CD4bs) of the HIV-1 envelope glycoprotein is susceptible to multiple lineages of broadly neutralizing antibodies (bnAbs) that are attractive to elicit with vaccines. The CH235 lineage (VH1-46) of CD4bs bnAbs is particularly attractive because the most mature members neutralize 90% of circulating strains, do not possess long HCDR3 regions, and do not contain insertions and deletions that may be difficult to induce. We used virus neutralization to measure the interaction of CH235 unmutated common ancestor (CH235 UCA) with functional Env trimers on infectious virions to guide immunogen design for this bnAb lineage. Two Env mutations were identified, one in loop D (N279K) and another in V5 (G458Y), that acted synergistically to render autologous CH505 transmitted/founder virus susceptible to neutralization by CH235 UCA. Man5-enriched N-glycans provided additional synergy for neutralization. CH235 UCA bound with nanomolar affinity to corresponding soluble native-like Env trimers as candidate immunogens. A cryo-EM structure of CH235 UCA bound to Man5-enriched CH505.N279K.G458Y.SOSIP.664 revealed interactions of the antibody light chain complementarity determining region 3 (CDR L3) with the engineered Env loops D and V5. These results demonstrate that virus neutralization can directly inform vaccine design and suggest a germline targeting and reverse engineering strategy to initiate and mature the CH235 bnAb lineage. Despite a wealth of information on the epitopes, ontogeny, structure and maturation pathways of multiple epitope classes of HIV-1 broadly neutralizing antibodies (bnAbs), there has been little progress eliciting similar antibodies by vaccination. One major contributing factor is the failure of many candidate immunogens to engage germline reverted forms of bnAbs, making it unlikely that they will provide adequate stimulation of appropriate naïve B cells to initiate bnAb lineages. Here we used virus neutralization to identify two point mutations and a modified glycan profile that together render HIV-1 CH505 Env-pseudotyped virus highly susceptible to neutralization by a germline-reverted form of the CH235 lineage of CD4 binding site (CD4bs) bnAbs. These same modifications permit strong binding of corresponding soluble native-like CH505 Env trimers to germline-reverted CH235. These observations provide a conceptual framework for the design and testing of novel immunogens that aim to elicit the CH235 bnAb lineage.
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13
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Conformational Engineering of HIV-1 Env Based on Mutational Tolerance in the CD4 and PG16 Bound States. J Virol 2019; 93:JVI.00219-19. [PMID: 30894475 DOI: 10.1128/jvi.00219-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 03/16/2019] [Indexed: 12/22/2022] Open
Abstract
HIV-1 infection is initiated by viral Env engaging the host receptor CD4, triggering Env to transition from a "closed" to "open" conformation during the early events of virus-cell membrane fusion. To understand how Env sequence accommodates this conformational change, mutational landscapes decoupled from virus replication were determined for Env from BaL (clade B) and DU422 (clade C) isolates interacting with CD4 or antibody PG16 that preferentially recognizes closed trimers. Sequence features uniquely important to each bound state were identified, including glycosylation and binding sites. Notably, the Env apical domain and trimerization interface are under selective pressure for PG16 binding. Based on this key observation, mutations were found that increase presentation of quaternary epitopes associated with properly conformed trimers when Env is expressed at the plasma membrane. Many mutations reduce electrostatic repulsion at the Env apex and increase PG16 recognition of Env sequences from clades A and B. Other mutations increase hydrophobic packing at the gp120 inner-outer domain interface and were broadly applicable for engineering Env from diverse strains spanning tiers 1, 2, and 3 across clades A, B, C, and BC recombinants. Core mutations predicted to introduce steric strain in the open state show markedly reduced CD4 interactions. Finally, we demonstrate how our methodology can be adapted to interrogate interactions between membrane-associated Env and the matrix domain of Gag. These findings and methods may assist vaccine design.IMPORTANCE HIV-1 Env is dynamic and undergoes large conformational changes that drive fusion of virus and host cell membranes. Three Env proteins in a trimer contact each other at their apical tips to form a closed conformation that presents epitopes recognized by broadly neutralizing antibodies. The apical tips separate, among other changes, to form an open conformation that binds tightly to host receptors. Understanding how Env sequence facilitates these structural changes can inform the biophysical mechanism and aid immunogen design. Using deep mutational scans decoupled from virus replication, we report mutational landscapes for Env from two strains interacting with conformation-dependent binding proteins. Residues in the Env trimer interface and apical domains are preferentially conserved in the closed conformation, and conformational diversity is facilitated by electrostatic repulsion and an underpacked core between domains. Specific mutations are described that enhance presentation of the trimeric closed conformation across diverse HIV-1 strains.
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14
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Cheedarla N, Sundaramurthi JC, Hemalatha B, Anangi B, Nesakumar M, Ashokkumar M, Vidya Vijayan K, Tripathy SP, Swaminathan S, Vaniambadi SK, Ramanathan DV, Hanna LE. Mapping of Neutralizing Antibody Epitopes on the Envelope of Viruses Obtained from Plasma Samples Exhibiting Broad Cross-Clade Neutralization Potential Against HIV-1. AIDS Res Hum Retroviruses 2019; 35:169-184. [PMID: 30328700 DOI: 10.1089/aid.2018.0224] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Several broadly neutralizing antibodies (bNAbs) that can target HIV strains with large degrees of variability have recently been identified. However, efforts to induce synthesis of such bNAbs that can protect against HIV infection have not met with much success. Identification of specific epitopes encoded in the HIV-1 envelope (Env) that can direct the host to synthesize bNAbs remains a challenge. In a previous study, we identified 12 antiretroviral therapy-naive HIV-1-infected individuals whose plasma exhibited broad cross-clade neutralization property against different clades of HIV-1. In this study, we sequenced the full-length HIV-1 gp160 from 11 of these individuals and analyzed the sequences to identify bNAb epitopes. We identified critical residues in the viral envelopes that contribute to the formation of conformational epitopes and possibly induce the production of bNAbs, using in silico methods. We found that many of the sequences had conserved glycans at positions N160 (10/11) and N332 (9/11), which are known to be critical for the binding of PG9/PG16-like and PGT128-like bNAbs, respectively. We also observed conservation of critical glycans at positions N234 and N276 critical for the interaction with CD4 binding site bNAbs in 8/11 and 11/11 sequences, respectively. We modeled the three-dimensional structure of the 11 HIV-1 envelopes and found that though each had structural differences, the critical residues were mostly present on the surface of the Env structures. The identified critical residues are proposed as candidates for further evaluation as bNAb epitopes.
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Affiliation(s)
- Narayanaiah Cheedarla
- Department of HIV/AIDS, National Institute for Research in Tuberculosis, Chennai, India
| | | | - Babu Hemalatha
- Department of HIV/AIDS, National Institute for Research in Tuberculosis, Chennai, India
| | - Brahmaiah Anangi
- Molecular Virology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
| | - Manohar Nesakumar
- Department of HIV/AIDS, National Institute for Research in Tuberculosis, Chennai, India
| | - Manickam Ashokkumar
- Department of HIV/AIDS, National Institute for Research in Tuberculosis, Chennai, India
| | - K.K. Vidya Vijayan
- Department of HIV/AIDS, National Institute for Research in Tuberculosis, Chennai, India
| | | | - Soumya Swaminathan
- Department of HIV/AIDS, National Institute for Research in Tuberculosis, Chennai, India
| | | | | | - Luke Elizabeth Hanna
- Department of HIV/AIDS, National Institute for Research in Tuberculosis, Chennai, India
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15
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Smith SA, Burton SL, Kilembe W, Lakhi S, Karita E, Price M, Allen S, Derdeyn CA. VH1-69 Utilizing Antibodies Are Capable of Mediating Non-neutralizing Fc-Mediated Effector Functions Against the Transmitted/Founder gp120. Front Immunol 2019; 9:3163. [PMID: 30697215 PMCID: PMC6341001 DOI: 10.3389/fimmu.2018.03163] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 12/21/2018] [Indexed: 01/05/2023] Open
Abstract
Multiple antibody effector functions arise in HIV-1 infection that could be harnessed to protect against infection or clear the persistent reservoir. Here, we have investigated the genetic and functional memory B cell and antibody landscape present during early infection in six individuals infected with either subtype A, C, or an A/C recombinant HIV-1. These individuals demonstrated varying levels of plasma autologous neutralization (nAb) against the transmitted/founder envelope (T/F Env) pseudovirus and non-neutralizing Fc-mediated effector function (nnFc) antibody-dependent cell-mediated cytotoxicity (ADCC) against the T/F Env gp120 protein at ~7 months after infection. Genetic analysis of the immunoglobulin heavy (VH) and light (VL) chain variable domain gene segments from 352 autologous T/F Env gp120-specific single B cells recovered at this same 7-month time-point revealed an over-representation of the VH1-69 germline in five of six individuals. A defining feature of the VH1-69 utilizing gp120-specific antibodies was their significantly more hydrophobic complementarity-determining region-2 (CDRH2) regions compared to other VH CDRH2 sequences from each individual. While none of the VH1-69 antibodies possessed strong neutralizing activity against virions pseudotyped with the autologous T/F Env, almost a third were capable of mediating high ADCC activity, as assayed by intracellular granzyme B activity in CEM.NKr.CCR5 target cells coated with autologous T/F Env gp120. High ADCC mediating VH1-69 antibodies exhibited shorter complementarity-determining region-3 (CDRH3) lengths and a more neutral isoelectric point than antibodies lacking this function. In the individual that developed the highest autologous ADCC responses, the high granzyme B producing antibodies bound to surface expressed envelope in the absence of CD4 and were not enhanced by the addition of soluble CD4. Overall, VH1-69 utilizing antibodies are commonly induced against gp120 in diverse HIV-1 infections and a subset of these antibodies can mediate ADCC functions, serving as a bridge between the innate and adaptive immune response to HIV-1.
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Affiliation(s)
- S Abigail Smith
- Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States.,Emory Vaccine Center, Emory University, Atlanta, GA, United States
| | - Samantha L Burton
- Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States.,Emory Vaccine Center, Emory University, Atlanta, GA, United States
| | | | - Shabir Lakhi
- Zambia Emory HIV Research Project, Lusaka, Zambia
| | | | - Matt Price
- International AIDS Vaccine Initiative, New York, NY, United States.,Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, CA, United States
| | - Susan Allen
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA, United States
| | - Cynthia A Derdeyn
- Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States.,Emory Vaccine Center, Emory University, Atlanta, GA, United States.,Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA, United States
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16
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Requirements for Empirical Immunogenicity Trials, Rather than Structure-Based Design, for Developing an Effective HIV Vaccine. HIV/AIDS: IMMUNOCHEMISTRY, REDUCTIONISM AND VACCINE DESIGN 2019. [PMCID: PMC7122000 DOI: 10.1007/978-3-030-32459-9_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
The claim that it is possible to rationally design a structure-based HIV-1 vaccine is based on misconceptions regarding the nature of protein epitopes and of immunological specificity. Attempts to use reverse vaccinology to generate an HIV-1 vaccine on the basis of the structure of viral epitopes bound to monoclonal neutralizing antibodies have failed so far because it was not possible to extrapolate from an observed antigenic structure to the immunogenic structure required in a vaccine. Vaccine immunogenicity depends on numerous extrinsic factors such as the host immunoglobulin gene repertoire, the presence of various cellular and regulatory mechanisms in the immunized host and the process of antibody affinity maturation. All these factors played a role in the appearance of the neutralizing antibody used to select the epitope to be investigated as potential vaccine immunogen, but they cannot be expected to be present in identical form in the host to be vaccinated. It is possible to rationally design and optimize an epitope to fit one particular antibody molecule or to improve the paratope binding efficacy of a monoclonal antibody intended for passive immunotherapy. What is not possible is to rationally design an HIV-1 vaccine immunogen that will elicit a protective polyclonal antibody response of predetermined efficacy. An effective vaccine immunogen can only be discovered by investigating experimentally the immunogenicity of a candidate molecule and demonstrating its ability to induce a protective immune response. It cannot be discovered by determining which epitopes of an engineered antigen molecule are recognized by a neutralizing monoclonal antibody. This means that empirical immunogenicity trials rather than structural analyses of antigens offer the best hope of discovering an HIV-1 vaccine.
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17
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No Evidence for Cross-reactivity of Virus-specific Antibodies With HLA Alloantigens. Transplantation 2018; 102:1844-1849. [DOI: 10.1097/tp.0000000000002369] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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18
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Mathew E, Zhu H, Connelly SM, Sullivan MA, Brewer MG, Piepenbrink MS, Kobie JJ, Dewhurst S, Dumont ME. Display of the HIV envelope protein at the yeast cell surface for immunogen development. PLoS One 2018; 13:e0205756. [PMID: 30335821 PMCID: PMC6193675 DOI: 10.1371/journal.pone.0205756] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Accepted: 10/01/2018] [Indexed: 11/22/2022] Open
Abstract
As a step toward the development of variant forms of Env with enhanced immunogenic properties, we have expressed the glycoprotein in the yeast surface display system in a form that can be subjected to random mutagenesis followed by screening for forms with enhanced binding to germline antibodies. To optimize the expression and immunogenicity of the yeast-displayed Env protein, we tested different approaches for cell wall anchoring, expression of gp120 and gp140 Env from different viral strains, the effects of introducing mutations designed to stabilize Env, and the effects of procedures for altering N-linked glycosylation of Env. We find that diverse forms of HIV envelope glycoprotein can be efficiently expressed at the yeast cell surface and that gp140 forms of Env are effectively cleaved by Kex2p, the yeast furin protease homolog. Multiple yeast-displayed gp120 and gp140 proteins are capable of binding to antibodies directed against the V3-variable loop, CD4 binding site, and gp41 membrane-proximal regions, including some antibodies whose binding is known to depend on Env conformation and N-linked glycan. Based on antibody recognition and sensitivity to glycosidases, yeast glycosylation patterns partially mimic high mannose-type N-glycosylation in mammalian cells. However, yeast-displayed Env is not recognized by some anti-Env antibodies sensitive to quaternary structure, suggesting either that the displayed protein exists in a monomeric state or that for these antibodies, yeast glycosylation in certain regions hinders recognition or access. Consistent with studies in other systems, reconstructed predicted unmutated precursors to anti-Env antibodies exhibit little affinity for the yeast-displayed envelope protein.
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Affiliation(s)
- Elizabeth Mathew
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Hong Zhu
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Sara M. Connelly
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Mark A. Sullivan
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Matthew G. Brewer
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Michael S. Piepenbrink
- Infectious Diseases Division, University of Rochester Medical Center, Rochester, NY, United States of America
| | - James J. Kobie
- Infectious Diseases Division, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Stephen Dewhurst
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Mark E. Dumont
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, NY, United States of America
- * E-mail:
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Kumar R, Kumari R, Khan L, Sankhyan A, Parray HA, Tiwari A, Wig N, Sinha S, Luthra K. Isolation and Characterization of Cross-Neutralizing Human Anti-V3 Single-Chain Variable Fragments (scFvs) Against HIV-1 from an Antigen Preselected Phage Library. Appl Biochem Biotechnol 2018; 187:1011-1027. [DOI: 10.1007/s12010-018-2862-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 08/13/2018] [Indexed: 02/07/2023]
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Neutralizing Antibody Responses following Long-Term Vaccination with HIV-1 Env gp140 in Guinea Pigs. J Virol 2018; 92:JVI.00369-18. [PMID: 29643249 PMCID: PMC6002713 DOI: 10.1128/jvi.00369-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 04/09/2018] [Indexed: 12/14/2022] Open
Abstract
A vaccination regimen capable of eliciting potent and broadly neutralizing antibodies (bNAbs) remains an unachieved goal of the HIV-1 vaccine field. Here, we report the immunogenicity of longitudinal prime/boost vaccination regimens with a panel of HIV-1 envelope (Env) gp140 protein immunogens over a period of 200 weeks in guinea pigs. We assessed vaccine regimens that included a monovalent clade C gp140 (C97ZA012 [C97]), a tetravalent regimen consisting of four clade C gp140s (C97ZA012, 459C, 405C, and 939C [4C]), and a tetravalent regimen consisting of clade A, B, C, and mosaic gp140s (92UG037, PVO.4, C97ZA012, and Mosaic 3.1, respectively [ABCM]). We found that the 4C and ABCM prime/boost regimens were capable of eliciting greater magnitude and breadth of binding antibody responses targeting variable loop 2 (V2) over time than the monovalent C97-only regimen. The longitudinal boosting regimen conducted over more than 2 years increased the magnitude of certain tier 1 NAb responses but did not increase the magnitude or breadth of heterologous tier 2 NAb responses. These data suggest that additional immunogen design strategies are needed to induce broad, high-titer tier 2 NAb responses.IMPORTANCE The elicitation of potent, broadly neutralizing antibodies (bNAbs) remains an elusive goal for the HIV-1 vaccine field. In this study, we explored the use of a long-term vaccination regimen with different immunogens to determine if we could elicit bNAbs in guinea pigs. We found that longitudinal boosting over more than 2 years increased tier 1 NAb responses but did not increase the magnitude and breadth of tier 2 NAb responses. These data suggest that additional immunogen designs and vaccination strategies will be necessary to induce broad tier 2 NAb responses.
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21
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Yates NL, deCamp AC, Korber BT, Liao HX, Irene C, Pinter A, Peacock J, Harris LJ, Sawant S, Hraber P, Shen X, Rerks-Ngarm S, Pitisuttithum P, Nitayapan S, Berman PW, Robb ML, Pantaleo G, Zolla-Pazner S, Haynes BF, Alam SM, Montefiori DC, Tomaras GD. HIV-1 Envelope Glycoproteins from Diverse Clades Differentiate Antibody Responses and Durability among Vaccinees. J Virol 2018; 92:e01843-17. [PMID: 29386288 PMCID: PMC5874409 DOI: 10.1128/jvi.01843-17] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2017] [Accepted: 12/18/2017] [Indexed: 11/20/2022] Open
Abstract
Induction of broadly cross-reactive antiviral humoral responses with the capacity to target globally diverse circulating strains is a key goal for HIV-1 immunogen design. A major gap in the field is the identification of diverse HIV-1 envelope antigens to evaluate vaccine regimens for binding antibody breadth. In this study, we define unique antigen panels to map HIV-1 vaccine-elicited antibody breadth and durability. Diverse HIV-1 envelope glycoproteins were selected based on genetic and geographic diversity to cover the global epidemic, with a focus on sexually acquired transmitted/founder viruses with a tier 2 neutralization phenotype. Unique antigenicity was determined by nonredundancy (Spearman correlation), and antigens were clustered using partitioning around medoids (PAM) to identify antigen diversity. Cross-validation demonstrated that the PAM method was better than selection by reactivity and random selection. Analysis of vaccine-elicited V1V2 binding antibody in longitudinal samples from the RV144 clinical trial revealed the striking heterogeneity among individual vaccinees in maintaining durable responses. These data support the idea that a major goal for vaccine development is to improve antibody levels, breadth, and durability at the population level. Elucidating the level and durability of vaccine-elicited binding antibody breadth needed for protection is critical for the development of a globally efficacious HIV vaccine.IMPORTANCE The path toward an efficacious HIV-1 vaccine will require characterization of vaccine-induced immunity that can recognize and target the highly genetically diverse virus envelope glycoproteins. Antibodies that target the envelope glycoproteins, including diverse sequences within the first and second hypervariable regions (V1V2) of gp120, were identified as correlates of risk for the one partially efficacious HIV-1 vaccine. To build upon this discovery, we experimentally and computationally evaluated humoral responses to define envelope glycoproteins representative of the antigenic diversity of HIV globally. These diverse envelope antigens distinguished binding antibody breadth and durability among vaccine candidates, thus providing insights for advancing the most promising HIV-1 vaccine candidates.
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Affiliation(s)
- Nicole L Yates
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Medicine, Duke University School of Medicine, Durham, North Carolina, USA
| | - Allan C deCamp
- Vaccine and Infectious Disease Division and Statistical Center for HIV/AIDS Research and Prevention, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Bette T Korber
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
| | - Hua-Xin Liao
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Medicine, Duke University School of Medicine, Durham, North Carolina, USA
| | - Carmela Irene
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| | - Abraham Pinter
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| | - James Peacock
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Medicine, Duke University School of Medicine, Durham, North Carolina, USA
| | - Linda J Harris
- Vaccine and Infectious Disease Division and Statistical Center for HIV/AIDS Research and Prevention, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Sheetal Sawant
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Medicine, Duke University School of Medicine, Durham, North Carolina, USA
| | - Peter Hraber
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
| | - Xiaoying Shen
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Medicine, Duke University School of Medicine, Durham, North Carolina, USA
| | - Supachai Rerks-Ngarm
- Thailand Ministry of Public Health, Department of Disease Control, Bangkok, Thailand
| | | | | | - Phillip W Berman
- Department of Biomedical Engineering, University of California, Santa Cruz, California, USA
| | - Merlin L Robb
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland, USA and the U.S. Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, Maryland, USA
| | - Giuseppe Pantaleo
- Service of Immunology and Allergy, Service of Infectious Diseases, Department of Medicine and Swiss Vaccine Research Institute, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland
| | | | - Barton F Haynes
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Medicine, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Immunology, Duke University School of Medicine, Durham, North Carolina, USA
| | - S Munir Alam
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Medicine, Duke University School of Medicine, Durham, North Carolina, USA
| | - David C Montefiori
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Surgery, Duke University School of Medicine, Durham, North Carolina, USA
| | - Georgia D Tomaras
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Immunology, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Surgery, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, USA
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22
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Analysis of HIV-1 envelope evolution suggests antibody-mediated selection of common epitopes among Chinese former plasma donors from a narrow-source outbreak. Sci Rep 2018; 8:5743. [PMID: 29636501 PMCID: PMC5893620 DOI: 10.1038/s41598-018-23913-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 03/20/2018] [Indexed: 12/31/2022] Open
Abstract
The HIV-1 envelope mutates rapidly to evade recognition and killing, and is a major target of humoral immune responses and vaccine development. Identification of common epitopes for vaccine development have been complicated by genetic variation on both virus and host levels. We studied HIV-1 envelope gp120 evolution in 12 Chinese former plasma donors infected with a purportedly single founder virus, with the aim of identifying common antibody epitopes under immune selection. We found five amino acid sites under significant positive selection in ≥50% of the study participants, and 22 sites consistent with antibody-mediated selection. Despite strong selection pressure, some sites housed a limited repertoire of amino acids. Structural modelling revealed that most of the variable amino acid sites were located on the exposed distal edge of the Gp120 trimer, whilst invariant sites clustered within the centre of the protein complex. Two sites, flanking the V3 hypervariable loop, represent novel antibody sites. Analysis of HIV-1 evolution in hosts infected with a narrow-source virus may provide insight and novel understanding of common epitopes under antibody-mediated selection. If verified in functional studies, such epitopes could be suitable as targets in vaccine development.
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23
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Identification of Novel Structural Determinants in MW965 Env That Regulate the Neutralization Phenotype and Conformational Masking Potential of Primary HIV-1 Isolates. J Virol 2018; 92:JVI.01779-17. [PMID: 29237828 DOI: 10.1128/jvi.01779-17] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 11/28/2017] [Indexed: 11/20/2022] Open
Abstract
The subtype C HIV-1 isolate MW965.26 is a highly neutralization-sensitive tier 1a primary isolate that is widely used in vaccine studies, but the basis for the sensitive neutralization phenotype of this isolate is not known. Substituting the MW965.26 V1/V2 domain into a neutralization-sensitive SF162 Env clone resulted in high resistance to standard anti-V3 monoclonal antibodies, demonstrating that this region possesses strong masking activity in a standard Env backbone and indicating that determinants elsewhere in MW965.26 Env are responsible for its unusual neutralization sensitivity. Key determinants for this phenotype were mapped by generating chimeric Envs between MW965.26 Env and a typical resistant Env clone, the consensus C (ConC) clone, and localized to two residues, Cys384 in the C3 domain and Asn502 in the C5 domain. Substituting the sensitizing mutations Y384C and K502N at these positions into several resistant primary Envs resulted in conversion to neutralization-sensitive phenotypes, demonstrating the generalizability of this effect. In contrast to the sensitizing effects of these substitutions on normally masked epitopes, these mutations reduced the sensitivity of VRC01-like epitopes overlapping the CD4-binding domain, while they had no effect on several other classes of broadly neutralizing epitopes, including members of several lineages of V2-dependent quaternary epitopes and representatives of N332 glycan-dependent epitopes (PGT121) and quaternary, cleavage-dependent epitopes centered at the gp41-gp120 interface on intact HIV-1 Env trimers (PGT151). These results identify novel substitutions in gp120 that regulate the expression of alternative conformations of Env and differentially affect the exposure of different classes of epitopes, thereby influencing the neutralization phenotype of primary HIV-1 isolates.IMPORTANCE A better understanding of the mechanisms that determine the wide range of neutralization sensitivity of circulating primary HIV-1 isolates would provide important information about the natural structural and conformational diversity of HIV-1 Env and how this affects the neutralization phenotype. A useful way of studying this is to determine the molecular basis for the unusually high neutralization sensitivities of the limited number of available tier 1a viruses. This study localized the neutralization sensitivity of MW965.26, an extremely sensitive subtype C-derived primary isolate, to two rare substitutions in the C3 and C5 domains and demonstrated that the sequences at these positions differentially affect the presentation of epitopes recognized by different classes of standard and conformation-dependent broadly neutralizing antibodies. These results provide novel insight into how these regions regulate the neutralization phenotype and provide tools for controlling the Env conformation that could have applications both for structural studies and in vaccine design.
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24
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Upadhyay C, Feyznezhad R, Yang W, Zhang H, Zolla-Pazner S, Hioe CE. Alterations of HIV-1 envelope phenotype and antibody-mediated neutralization by signal peptide mutations. PLoS Pathog 2018; 14:e1006812. [PMID: 29370305 PMCID: PMC5800646 DOI: 10.1371/journal.ppat.1006812] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 02/06/2018] [Accepted: 12/14/2017] [Indexed: 11/18/2022] Open
Abstract
HIV-1 envelope glycoprotein (Env) mediates virus attachment and entry into the host cells. Like other membrane-bound and secreted proteins, HIV-1 Env contains at its N terminus a signal peptide (SP) that directs the nascent Env to the endoplasmic reticulum (ER) where Env synthesis and post-translational modifications take place. SP is cleaved during Env biosynthesis but potentially influences the phenotypic traits of the Env protein. The Env SP sequences of HIV-1 isolates display high sequence variability, and the significance of such variability is unclear. We postulate that changes in the Env SP influence Env transport through the ER-Golgi secretory pathway and Env folding and/or glycosylation that impact on Env incorporation into virions, receptor binding and antibody recognition. We first evaluated the consequences of mutating the charged residues in the Env SP in the context of infectious molecular clone HIV-1 REJO.c/2864. Results show that three different mutations affecting histidine at position 12 affected Env incorporation into virions that correlated with reduction of virus infectivity and DC-SIGN-mediated virus capture and transmission. Mutations at positions 8, 12, and 15 also rendered the virus more resistant to neutralization by monoclonal antibodies against the Env V1V2 region. These mutations affected the oligosaccharide composition of N-glycans as shown by changes in Env reactivity with specific lectins and by mass spectrometry. Increased neutralization resistance and N-glycan composition changes were also observed when analogous mutations were introduced to another HIV-1 strain, JRFL. To the best of our knowledge, this is the first study showing that certain residues in the HIV-1 Env SP can affect virus neutralization sensitivity by modulating oligosaccharide moieties on the Env N-glycans. The HIV-1 Env SP sequences thus may be under selective pressure to balance virus infectiousness with virus resistance to the host antibody responses. (289 words) HIV-1 envelope glycoprotein (Env) is indispensable for virus infection. HIV-1 Env contains at its N terminus a signal peptide (SP) that directs the protein to the endoplasmic reticulum. The SP sequences exhibits high variability among HIV-1 isolates, and the significance of such variability is unclear. We hypothesize that changes in the Env SP influence the Env biogenesis, Env folding and/or glycosylation and the phenotypic traits of the virus. This study evaluated the consequences of mutations in the Env SP of infectious molecular clone HIV-1 REJO.c/2864. Results show that three different mutations affecting histidine at position 12 impacted on the Env incorporation into virions that correlated with virus infectivity and transmission. Additionally, Env SP mutations at positions 8, 12, and 15 increased virus resistance to neutralization by Env monoclonal antibodies. These mutations also altered the oligosaccharide composition of N-glycans on Env as shown by changes in the Env reactivity with lectins and by mass spectrometry. Similar phenotypic changes were observed when analogous SP mutations were introduced to another virus strain, JRFL. Thus, the HIV-1 Env SP controls Env expression and glycosylation that affect virus infectivity, transmission, and sensitivity to neutralization by antibodies. (191 words)
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Affiliation(s)
- Chitra Upadhyay
- Icahn School of Medicine at Mount Sinai, Division of Infectious Diseases, New York, New York, United States of America
- * E-mail: (CU); (CEH)
| | - Roya Feyznezhad
- Icahn School of Medicine at Mount Sinai, Division of Infectious Diseases, New York, New York, United States of America
| | - Weiming Yang
- Department of Pathology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Hui Zhang
- Department of Pathology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Susan Zolla-Pazner
- Icahn School of Medicine at Mount Sinai, Division of Infectious Diseases, New York, New York, United States of America
| | - Catarina E. Hioe
- Icahn School of Medicine at Mount Sinai, Division of Infectious Diseases, New York, New York, United States of America
- James J. Peters Veterans Affairs Medical Center, Research Service, Bronx, New York, United States of America
- * E-mail: (CU); (CEH)
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25
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Chuang GY, Geng H, Pancera M, Xu K, Cheng C, Acharya P, Chambers M, Druz A, Tsybovsky Y, Wanninger TG, Yang Y, Doria-Rose NA, Georgiev IS, Gorman J, Joyce MG, O'Dell S, Zhou T, McDermott AB, Mascola JR, Kwong PD. Structure-Based Design of a Soluble Prefusion-Closed HIV-1 Env Trimer with Reduced CD4 Affinity and Improved Immunogenicity. J Virol 2017; 91:e02268-16. [PMID: 28275193 PMCID: PMC5411596 DOI: 10.1128/jvi.02268-16] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 03/03/2017] [Indexed: 01/09/2023] Open
Abstract
The HIV-1 envelope (Env) trimer is a target for vaccine design as well as a conformational machine that facilitates virus entry by transitioning between prefusion-closed, CD4-bound, and coreceptor-bound conformations by transitioning into a postfusion state. Vaccine designers have sought to restrict the conformation of the HIV-1 Env trimer to its prefusion-closed state as this state is recognized by most broadly neutralizing, but not nonneutralizing, antibodies. We previously identified a disulfide bond, I201C-A433C (DS), which stabilizes Env in the vaccine-desired prefusion-closed state. When placed into the context of BG505 SOSIP.664, a soluble Env trimer mimic developed by Sanders, Moore, and colleagues, the engineered DS-SOSIP trimer showed reduced conformational triggering by CD4. Here, we further stabilize DS-SOSIP through a combination of structure-based design and 96-well-based expression and antigenic assessment. From 103 designs, we identified one, named DS-SOSIP.4mut, with four additional mutations at the interface of potentially mobile domains of the prefusion-closed structure. We also determined the crystal structures of DS-SOSIP.4mut at 4.1-Å resolution and of an additional DS-SOSIP.6mut variant at 4.3-Å resolution, and these confirmed the formation of engineered disulfide bonds. Notably, DS-SOSIP.4mut elicited a higher ratio of tier 2 autologous titers versus tier 1 V3-sensitive titers than BG505 SOSIP.664. DS-SOSIP.4mut also showed reduced recognition of CD4 and increased thermostability. The improved antigenicity, thermostability, and immunogenicity of DS-SOSIP.4mut suggest utility as an immunogen or a serologic probe; moreover, the specific four alterations identified here, M154, M300, M302, and L320 (4mut), can also be transferred to other HIV-1 Env trimers of interest to improve their properties.IMPORTANCE One approach to elicit broadly neutralizing antibodies against HIV-1 is to stabilize the structurally flexible HIV-1 envelope (Env) trimer in a conformation that displays predominantly broadly neutralizing epitopes and few to no nonneutralizing epitopes. The prefusion-closed conformation of HIV-1 Env has been identified as one such preferred conformation, and a current leading vaccine candidate is the BG505 DS-SOSIP variant, comprising two disulfides and an Ile-to-Pro mutation of Env from strain BG505. Here, we introduced additional mutations to further stabilize BG505 DS-SOSIP in the vaccine-preferred prefusion-closed conformation. In guinea pigs, our best mutant, DS-SOSIP.4mut, elicited a significantly higher ratio of autologous versus V3-directed neutralizing antibody responses than the SOSIP-stabilized form. We also observed an improvement in thermostability and a reduction in CD4 affinity. With improved antigenicity, stability, and immunogenicity, DS-SOSIP.4mut-stabilized trimers may have utility as HIV-1 immunogens or in other antigen-specific contexts, such as with B-cell probes.
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Affiliation(s)
- Gwo-Yu Chuang
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Hui Geng
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Marie Pancera
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Kai Xu
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Cheng Cheng
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Priyamvada Acharya
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Michael Chambers
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Aliaksandr Druz
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Yaroslav Tsybovsky
- Electron Microscopy Laboratory, Cancer Research Technology Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
| | - Timothy G Wanninger
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Yongping Yang
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Nicole A Doria-Rose
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Ivelin S Georgiev
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Jason Gorman
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - M Gordon Joyce
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Sijy O'Dell
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Tongqing Zhou
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Adrian B McDermott
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - John R Mascola
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Peter D Kwong
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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26
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Monoclonal Antibodies Specific for the V2, V3, CD4-Binding Site, and gp41 of HIV-1 Mediate Phagocytosis in a Dose-Dependent Manner. J Virol 2017; 91:JVI.02325-16. [PMID: 28122974 DOI: 10.1128/jvi.02325-16] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 01/13/2017] [Indexed: 11/20/2022] Open
Abstract
In light of the weak or absent neutralizing activity mediated by anti-V2 monoclonal antibodies (MAbs), we tested whether they can mediate Ab-dependent cellular phagocytosis (ADCP), which is an important element of anti-HIV-1 immunity. We tested six anti-V2 MAbs and compared them with 21 MAbs specific for V3, the CD4-binding site (CD4bs), and gp41 derived from chronically HIV-1-infected individuals and produced by hybridoma cells. ADCP activity was measured by flow cytometry using uptake by THP-1 monocytic cells of fluorescent beads coated with gp120, gp41, BG505 SOSIP.664, or BG505 DS-SOSIP.664 complexed with MAbs. The measurement of ADCP activity by the area under the curve showed significantly higher activity of anti-gp41 MAbs than of the members of the three other groups of MAbs tested using beads coated with monomeric gp41 or gp120; anti-V2 MAbs were dominant compared to anti-V3 and anti-CD4bs MAbs against clade C gp120ZM109 ADCP activity mediated by V2 and V3 MAbs was positive against stabilized DS-SOSIP.664 trimer but negligible against SOSIP.664 targets, suggesting that a closed envelope conformation better exposes the variable loops. Two IgG3 MAbs against the V2 and V3 regions displayed dominant ADCP activity compared to a panel of IgG1 MAbs. This superior ADCP activity was confirmed when two of three recombinant IgG3 anti-V2 MAbs were compared to their IgG1 counterparts. The study demonstrated dominant ADCP activity of anti-gp41 against monomers but not trimers, with some higher activity of anti-V2 MAbs than of anti-V3 and anti-CD4bs MAbs. The ability to mediate ADCP suggests a mechanism by which anti-HIV-1 envelope Abs can contribute to protective efficacy.IMPORTANCE Anti-V2 antibodies (Abs) correlated with reduced risk of HIV-1 infection in recipients of the RV144 vaccine, suggesting that they play a protective role, but a mechanism providing such protection remains to be determined. The rare and weak neutralizing activities of anti-V2 MAbs prompted us to study Fc-mediated activities. We compared anti-V2 MAbs with other MAbs specific for V3, CD4bs, and gp41 for Ab-dependent cellular phagocytosis (ADCP) activity, implicated in protective immunity. The anti-V2 MAbs displayed stronger activity than other anti-gp120 MAbs in screening against one of two gp120s and against DS-SOSIP, which mimics the native trimer. The activity of anti-gp41 MAbs was superior in targeting monomeric gp41 but was comparable to that seen against trimers, which may not adequately expose gp41 epitopes. While anti-envelope MAbs in general mediated ADCP activity, anti-V2 MAbs displayed some dominance compared to other MAbs. Our demonstration that anti-V2 MAbs mediate ADCP activity suggests a functional mechanism for their contribution to protective efficacy.
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27
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Khan L, Kumar R, Thiruvengadam R, Parray HA, Makhdoomi MA, Kumar S, Aggarwal H, Mohata M, Hussain AW, Das R, Varadarajan R, Bhattacharya J, Vajpayee M, Murugavel KG, Solomon S, Sinha S, Luthra K. Cross-neutralizing anti-HIV-1 human single chain variable fragments(scFvs) against CD4 binding site and N332 glycan identified from a recombinant phage library. Sci Rep 2017; 7:45163. [PMID: 28332627 PMCID: PMC5362912 DOI: 10.1038/srep45163] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 02/15/2017] [Indexed: 11/30/2022] Open
Abstract
More than 50% of HIV-1 infection globally is caused by subtype_C viruses. Majority of the broadly neutralizing antibodies (bnAbs) targeting HIV-1 have been isolated from non-subtype_C infected donors. Mapping the epitope specificities of bnAbs provides useful information for vaccine design. Recombinant antibody technology enables generation of a large repertoire of monoclonals with diverse specificities. We constructed a phage recombinant single chain variable fragment (scFv) library with a diversity of 7.8 × 108 clones, using a novel strategy of pooling peripheral blood mononuclear cells (PBMCs) of six select HIV-1 chronically infected Indian donors whose plasma antibodies exhibited potent cross neutralization efficiency. The library was panned and screened by phage ELISA using trimeric recombinant proteins to identify viral envelope specific clones. Three scFv monoclonals D11, C11 and 1F6 selected from the library cross neutralized subtypes A, B and C viruses at concentrations ranging from 0.09 μg/mL to 100 μg/mL. The D11 and 1F6 scFvs competed with mAbs b12 and VRC01 demonstrating CD4bs specificity, while C11 demonstrated N332 specificity. This is the first study to identify cross neutralizing scFv monoclonals with CD4bs and N332 glycan specificities from India. Cross neutralizing anti-HIV-1 human scFv monoclonals can be potential candidates for passive immunotherapy and for guiding immunogen design.
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Affiliation(s)
- Lubina Khan
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India
| | - Rajesh Kumar
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India
| | | | - Hilal Ahmad Parray
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India
| | | | - Sanjeev Kumar
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India
| | - Heena Aggarwal
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India
| | - Madhav Mohata
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India
| | - Abdul Wahid Hussain
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India
| | - Raksha Das
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
| | | | - Jayanta Bhattacharya
- HIV Vaccine Translational Research Laboratory, Translational Health Science and Technology Institute, NCR Biotech Science Cluster, Faridabad, Haryana, India.,International AIDS Vaccine initiative, USA
| | - Madhu Vajpayee
- Department of Microbiology, All India Institute of Medical Sciences, New Delhi, India
| | - K G Murugavel
- Y.R. Gaitonde Centre for AIDS Research and Education (YRG CARE), Chennai, India
| | - Suniti Solomon
- Y.R. Gaitonde Centre for AIDS Research and Education (YRG CARE), Chennai, India
| | - Subrata Sinha
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India.,National Brain Research Centre, Manesar, Gurgaon, Haryana, India
| | - Kalpana Luthra
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India
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28
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Van Regenmortel MHV. Structure-Based Reverse Vaccinology Failed in the Case of HIV Because it Disregarded Accepted Immunological Theory. Int J Mol Sci 2016; 17:E1591. [PMID: 27657055 PMCID: PMC5037856 DOI: 10.3390/ijms17091591] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 08/30/2016] [Accepted: 09/07/2016] [Indexed: 12/14/2022] Open
Abstract
Two types of reverse vaccinology (RV) should be distinguished: genome-based RV for bacterial vaccines and structure-based RV for viral vaccines. Structure-based RV consists in trying to generate a vaccine by first determining the crystallographic structure of a complex between a viral epitope and a neutralizing monoclonal antibody (nMab) and then reconstructing the epitope by reverse molecular engineering outside the context of the native viral protein. It is based on the unwarranted assumption that the epitope designed to fit the nMab will have acquired the immunogenic capacity to elicit a polyclonal antibody response with the same protective capacity as the nMab. After more than a decade of intensive research using this type of RV, this approach has failed to deliver an effective, preventive HIV-1 vaccine. The structure and dynamics of different types of HIV-1 epitopes and of paratopes are described. The rational design of an anti-HIV-1 vaccine is shown to be a misnomer since investigators who claim that they design a vaccine are actually only improving the antigenic binding capacity of one epitope with respect to only one paratope and not the immunogenic capacity of an epitope to elicit neutralizing antibodies. Because of the degeneracy of the immune system and the polyspecificity of antibodies, each epitope studied by the structure-based RV procedure is only one of the many epitopes that the particular nMab is able to recognize and there is no reason to assume that this nMab must have been elicited by this one epitope of known structure. Recent evidence is presented that the trimeric Env spikes of the virus possess such an enormous plasticity and intrinsic structural flexibility that it is it extremely difficult to determine which Env regions are the best candidate vaccine immunogens most likely to elicit protective antibodies.
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Affiliation(s)
- Marc H V Van Regenmortel
- UMR 7242 Biotechnologie et Signalisation Cellulaire, Université de Strasbourg-CNRS, 300, Boulevard Sébastien Brant, CS 10413, 67412 Illkirch Cedex, France.
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29
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Makhdoomi MA, Singh D, Nair Pananghat A, Lodha R, Kabra SK, Luthra K. Neutralization resistant HIV-1 primary isolates from antiretroviral naïve chronically infected children in India. Virology 2016; 499:105-113. [PMID: 27643887 DOI: 10.1016/j.virol.2016.09.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 09/09/2016] [Accepted: 09/10/2016] [Indexed: 10/21/2022]
Abstract
Anti-HIV-1 broadly neutralizing antibodies (bnAbs) have been extensively tested against pesudoviruses of diverse strains. We generated and characterized HIV-1 primary isolates from antiretroviral naïve infected Indian children, and determined their susceptibility to known NAbs. All the 8 isolates belonged to subtype-C and were R5 tropic. Majority of these viruses were resistant to neutralization by NAbs, suggesting that the bnAbs, known to efficiently neutralize pseudoviruses (adult and pediatric) of different strains, are less effective against pediatric primary isolates. Interestingly, AIIMS_329 isolate displayed high susceptibility to neutralization by PG9 and PG16bnAbs, with IC50 titer of 1.3 and 0.97μg/ml, suggesting exposure of this epitope on this virus. All isolates except AIIMS_506 were neutralized by contemporaneous plasma antibodies. Our findings suggest that primary isolates, due to close resemblance to viruses in natural infection, should be used to evaluate NAbs as effective vaccine candidates in both children and adults.
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Affiliation(s)
| | - Deepti Singh
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Ambili Nair Pananghat
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi 110029, India; Department of Biochemistry, Jamia Hamdard University, 110062 New Delhi, India
| | - Rakesh Lodha
- Department of Pediatrics, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Sushil Kumar Kabra
- Department of Pediatrics, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Kalpana Luthra
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi 110029, India.
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30
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Zhao C, Ao Z, Yao X. Current Advances in Virus-Like Particles as a Vaccination Approach against HIV Infection. Vaccines (Basel) 2016; 4:vaccines4010002. [PMID: 26805898 PMCID: PMC4810054 DOI: 10.3390/vaccines4010002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 12/31/2015] [Accepted: 01/18/2016] [Indexed: 12/16/2022] Open
Abstract
HIV-1 virus-like particles (VLPs) are promising vaccine candidates against HIV-1 infection. They are capable of preserving the native conformation of HIV-1 antigens and priming CD4+ and CD8+ T cell responses efficiently via cross presentation by both major histocompatibility complex (MHC) class I and II molecules. Progress has been achieved in the preclinical research of HIV-1 VLPs as prophylactic vaccines that induce broadly neutralizing antibodies and potent T cell responses. Moreover, the progress in HIV-1 dendritic cells (DC)-based immunotherapy provides us with a new vision for HIV-1 vaccine development. In this review, we describe updates from the past 5 years on the development of HIV-1 VLPs as a vaccine candidate and on the combined use of HIV particles with HIV-1 DC-based immunotherapy as efficient prophylactic and therapeutic vaccination strategies.
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Affiliation(s)
- Chongbo Zhao
- Laboratory of Molecular Human Retrovirology, Department of Medical Microbiology, Faculty of Medicine, University of Manitoba, Winnipeg, MB R3E 0J9, Canada.
| | - Zhujun Ao
- Laboratory of Molecular Human Retrovirology, Department of Medical Microbiology, Faculty of Medicine, University of Manitoba, Winnipeg, MB R3E 0J9, Canada.
| | - Xiaojian Yao
- Laboratory of Molecular Human Retrovirology, Department of Medical Microbiology, Faculty of Medicine, University of Manitoba, Winnipeg, MB R3E 0J9, Canada.
- Department of Microbiology, School of Basic Medical Sciences, Central South University, Changsha 410078, Hunan, China.
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31
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Zolla-Pazner S, Cohen SS, Boyd D, Kong XP, Seaman M, Nussenzweig M, Klein F, Overbaugh J, Totrov M. Structure/Function Studies Involving the V3 Region of the HIV-1 Envelope Delineate Multiple Factors That Affect Neutralization Sensitivity. J Virol 2016; 90:636-49. [PMID: 26491157 PMCID: PMC4702699 DOI: 10.1128/jvi.01645-15] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Accepted: 10/04/2015] [Indexed: 01/13/2023] Open
Abstract
UNLABELLED Antibodies (Abs) specific for the V3 loop of the HIV-1 gp120 envelope neutralize most tier 1 and many tier 2 viruses and are present in essentially all HIV-infected individuals as well as immunized humans and animals. Vaccine-induced V3 Abs are associated with reduced HIV infection rates in humans and affect the nature of transmitted viruses in infected vaccinees, despite the fact that V3 is often occluded in the envelope trimer. Here, we link structural and experimental data showing how conformational alterations of the envelope trimer render viruses exceptionally sensitive to V3 Abs. The experiments interrogated the neutralization sensitivity of pseudoviruses with single amino acid mutations in various regions of gp120 that were predicted to alter packing of the V3 loop in the Env trimer. The results indicate that the V3 loop is metastable in the envelope trimer on the virion surface, flickering between states in which V3 is either occluded or available for binding to chemokine receptors (leading to infection) and to V3 Abs (leading to virus neutralization). The spring-loaded V3 in the envelope trimer is easily released by disruption of the stability of the V3 pocket in the unliganded trimer or disruption of favorable V3/pocket interactions. Formation of the V3 pocket requires appropriate positioning of the V1V2 domain, which is, in turn, dependent on the conformation of the bridging sheet and on the stability of the V1V2 B-C strand-connecting loop. IMPORTANCE The levels of antibodies to the third variable region (V3) of the HIV envelope protein correlate with reduced HIV infection rates. Previous studies showed that V3 is often occluded, as it sits in a pocket of the envelope trimer on the surface of virions; however, the trimer is flexible, allowing occluded portions of the envelope (like V3) to flicker into an exposed position that binds antibodies. Here we provide a systematic interrogation of mechanisms by which single amino acid changes in various regions of gp120 (i) render viruses sensitive to neutralization by V3 antibodies, (ii) result in altered packing of the V3 loop, and (iii) activate an open conformation that exposes V3 to the effects of V3 Abs. Taken together, these and previous studies explain how V3 antibodies can protect against HIV-1 infection and why they should be one of the targets of vaccine-induced antibodies.
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Affiliation(s)
- Susan Zolla-Pazner
- Veterans Affairs New York Harbor Healthcare System, New York, New York, USA Departments of Pathology and Biochemistry, New York University School of Medicine, New York, New York, USA
| | - Sandra Sharpe Cohen
- Departments of Pathology and Biochemistry, New York University School of Medicine, New York, New York, USA
| | - David Boyd
- Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Xiang-Peng Kong
- Departments of Pathology and Biochemistry, New York University School of Medicine, New York, New York, USA
| | - Michael Seaman
- Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | | | | | - Julie Overbaugh
- Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Max Totrov
- Molsoft, L.L.C., San Diego, California, USA
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32
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Deng L, Chen Z. An Integrated Framework for Functional Annotation of Protein Structural Domains. IEEE/ACM TRANSACTIONS ON COMPUTATIONAL BIOLOGY AND BIOINFORMATICS 2015; 12:902-13. [PMID: 26357331 DOI: 10.1109/tcbb.2015.2389213] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Structural domains are evolutionary and functional units of proteins and play a critical role in comparative and functional genomics. Computational assignment of domain function with high reliability is essential for understanding whole-protein functions. However, functional annotations are conventionally assigned onto full-length proteins rather than associating specific functions to the individual structural domains. In this article, we present Structural Domain Annotation (SDA), a novel computational approach to predict functions for SCOP structural domains. The SDA method integrates heterogeneous information sources, including structure alignment based protein-SCOP mapping features, InterPro2GO mapping information, PSSM Profiles, and sequence neighborhood features, with a Bayesian network. By large-scale annotating Gene Ontology terms to SCOP domains with SDA, we obtained a database of SCOP domain to Gene Ontology mappings, which contains ~162,000 out of the approximately 166,900 domains in SCOPe 2.03 (>97 percent) and their predicted Gene Ontology functions. We have benchmarked SDA using a single-domain protein dataset and an independent dataset from different species. Comparative studies show that SDA significantly outperforms the existing function prediction methods for structural domains in terms of coverage and maximum F-measure.
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Functional and Structural Characterization of Human V3-Specific Monoclonal Antibody 2424 with Neutralizing Activity against HIV-1 JRFL. J Virol 2015; 89:9090-102. [PMID: 26109728 PMCID: PMC4524078 DOI: 10.1128/jvi.01280-15] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 06/06/2015] [Indexed: 01/07/2023] Open
Abstract
UNLABELLED The V3 region of HIV-1 gp120 is important for virus-coreceptor interaction and highly immunogenic. Although most anti-V3 antibodies neutralize only the sensitive tier 1 viruses, anti-V3 antibodies effective against the more resistant viruses exist, and a better understanding of these antibodies and their epitopes would be beneficial for the development of novel vaccine immunogens against HIV. The HIV-1 isolate JRFL with its cryptic V3 is resistant to most V3-specific monoclonal antibodies (MAbs). However, the V3 MAb 2424 achieves 100% neutralization against JRFL. 2424 is encoded by IGHV3-53 and IGLV2-28 genes, a pairing rarely used by the other V3 MAbs. 2424 also has distinct binding and neutralization profiles. Studies of 2424-mediated neutralization of JRFL produced with a mannosidase inhibitor further revealed that its neutralizing activity is unaffected by the glycan composition of the virus envelope. To understand the distinct activity of 2424, we determined the crystal structure of 2424 Fab in complex with a JRFL V3 peptide and showed that the 2424 epitope is located at the tip of the V3 crown ((307)IHIGPGRAFYT(319)), dominated by interactions with His(P308), Pro(P313), and Arg(P315). The binding mode of 2424 is similar to that of the well-characterized MAb 447-52D, although 2424 is more side chain dependent. The 2424 epitope is focused on the very apex of V3, away from nearby glycans, facilitating antibody access. This feature distinguishes the 2424 epitope from the other V3 crown epitopes and indicates that the tip of V3 is a potential site to target and incorporate into HIV vaccine immunogens. IMPORTANCE HIV/AIDS vaccines are crucial for controlling the HIV epidemics that continue to afflict millions of people worldwide. However, HIV vaccine development has been hampered by significant scientific challenges, one of which is the inability of HIV vaccine candidates evaluated thus far to elicit production of potent and broadly neutralizing antibodies. The V3 loop is one of the few immunogenic targets on the virus envelope glycoprotein that can induce neutralizing antibodies, but in many viruses, parts of V3 are inaccessible for antibody recognition. This study examined a V3-specific monoclonal antibody that can completely neutralize HIV-1 JRFL, a virus isolate resistant to most V3 antibodies. Our data reveal that this antibody recognizes the most distal tip of V3, which is not as occluded as other parts of V3. Hence, the epitope of 2424 is in one of the vulnerable sites on the virus that may be exploited in designing HIV vaccine immunogens.
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34
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Li L, Wang XH, Williams C, Volsky B, Steczko O, Seaman MS, Luthra K, Nyambi P, Nadas A, Giudicelli V, Lefranc MP, Zolla-Pazner S, Gorny MK. A broad range of mutations in HIV-1 neutralizing human monoclonal antibodies specific for V2, V3, and the CD4 binding site. Mol Immunol 2015; 66:364-74. [PMID: 25965315 DOI: 10.1016/j.molimm.2015.04.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 04/16/2015] [Accepted: 04/20/2015] [Indexed: 12/25/2022]
Abstract
The HIV vaccine-induced neutralizing antibodies (Abs) display low rates of mutation in their variable regions. To determine the range of neutralization mediated by similar human monoclonal Abs (mAbs) but derived from unselected chronically HIV-1 infected subjects, we tested a panel of 66 mAbs specific to V3, CD4 binding site (CD4bs) and V2 regions. The mAbs were tested against 41 pseudoviruses, including 15 tier 1 and 26 tier 2, 3 viruses, showing that the neutralization potency and breadth of anti-V3 mAbs were significantly higher than those of the anti-CD4bs and anti-V2 mAbs, and only anti-V3 mAbs were able to neutralize some tier 2, 3 viruses. The percentage of mutations in the variable regions of the heavy (VH) and light (VL) chains varied broadly in a range from 2% to 18% and correlated moderately with the neutralization breadth of tier 2, 3 viruses. There was no correlation with neutralization of tier 1 viruses as some mAbs with low and high percentages of mutations neutralized the same number of viruses. The electrostatic interactions between anti-V3 mAbs and the charged V3 region may contribute to their neutralization because the isoelectric points of the VH CDR3 of 48 anti-V3 mAbs were inversely correlated with the neutralization breadth of tier 2, 3 viruses. The results demonstrate that infection-induced antibodies to CD4bs, V3 and V2 regions can mediate cross-clade neutralization despite low levels of mutations which can be achieved by HIV-1 vaccine-induced antibodies.
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Affiliation(s)
- Liuzhe Li
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
| | - Xiao-Hong Wang
- Veterans Affairs Medical Center, New York, NY 10010, USA
| | - Constance Williams
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
| | - Barbara Volsky
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
| | - Olivia Steczko
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
| | - Michael S Seaman
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Kalpana Luthra
- All India Institute of Medical Sciences, New Delhi, India
| | - Phillipe Nyambi
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
| | - Arthur Nadas
- Institute of Environmental Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Véronique Giudicelli
- IMGT(®), The International ImMunoGeneTics Information System(®), CNRS, Montpellier University, Montpellier, France
| | - Marie-Paule Lefranc
- IMGT(®), The International ImMunoGeneTics Information System(®), CNRS, Montpellier University, Montpellier, France
| | - Susan Zolla-Pazner
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA; Veterans Affairs Medical Center, New York, NY 10010, USA
| | - Miroslaw K Gorny
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA.
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Kirby KA, Ong YT, Hachiya A, Laughlin TG, Chiang LA, Pan Y, Moran JL, Marchand B, Singh K, Gallazzi F, Quinn TP, Yoshimura K, Murakami T, Matsushita S, Sarafianos SG. Structural basis of clade-specific HIV-1 neutralization by humanized anti-V3 monoclonal antibody KD-247. FASEB J 2014; 29:70-80. [PMID: 25351987 DOI: 10.1096/fj.14-252262] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Humanized monoclonal antibody KD-247 targets the Gly(312)-Pro(313)-Gly(314)-Arg(315) arch of the third hypervariable (V3) loop of the HIV-1 surface glycoprotein. It potently neutralizes many HIV-1 clade B isolates, but not of other clades. To understand the molecular basis of this specificity, we solved a high-resolution (1.55 Å) crystal structure of the KD-247 antigen binding fragment and examined the potential interactions with various V3 loop targets. Unlike most antibodies, KD-247 appears to interact with its target primarily through light chain residues. Several of these interactions involve Arg(315) of the V3 loop. To evaluate the role of light chain residues in the recognition of the V3 loop, we generated 20 variants of KD-247 single-chain variable fragments with mutations in the antigen-binding site. Purified proteins were assessed for V3 loop binding using AlphaScreen technology and for HIV-1 neutralization. Our data revealed that recognition of the clade-specificity defining residue Arg(315) of the V3 loop is based on a network of interactions that involve Tyr(L32), Tyr(L92), and Asn(L27d) that directly interact with Arg(315), thus elucidating the molecular interactions of KD-247 with its V3 loop target.
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Affiliation(s)
- Karen A Kirby
- Christopher S. Bond Life Sciences Center, Department of Molecular Microbiology and Immunology, School of Medicine
| | - Yee Tsuey Ong
- Christopher S. Bond Life Sciences Center, Department of Molecular Microbiology and Immunology, School of Medicine
| | - Atsuko Hachiya
- Christopher S. Bond Life Sciences Center, Department of Molecular Microbiology and Immunology, School of Medicine
| | - Thomas G Laughlin
- Christopher S. Bond Life Sciences Center, Department of Molecular Microbiology and Immunology, School of Medicine
| | - Leslie A Chiang
- Christopher S. Bond Life Sciences Center, Department of Molecular Microbiology and Immunology, School of Medicine
| | - Yun Pan
- Christopher S. Bond Life Sciences Center, Department of Molecular Microbiology and Immunology, School of Medicine
| | - Jennifer L Moran
- Christopher S. Bond Life Sciences Center, Department of Molecular Microbiology and Immunology, School of Medicine
| | - Bruno Marchand
- Christopher S. Bond Life Sciences Center, Department of Molecular Microbiology and Immunology, School of Medicine
| | - Kamalendra Singh
- Christopher S. Bond Life Sciences Center, Department of Molecular Microbiology and Immunology, School of Medicine
| | | | - Thomas P Quinn
- Department of Biochemistry, University of Missouri, Columbia, Missouri, USA
| | - Kazuhisa Yoshimura
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Toshio Murakami
- The Chemo-Sero-Therapeutic Research Institute (Kaketsuken), Kyokushi, Kikuchi, Kumamoto, Japan; and
| | - Shuzo Matsushita
- Division of Clinical Retrovirology and Infectious Diseases, Center for AIDS Research, Kumamoto University, Kumamoto, Japan
| | - Stefan G Sarafianos
- Christopher S. Bond Life Sciences Center, Department of Molecular Microbiology and Immunology, School of Medicine, Department of Biochemistry, University of Missouri, Columbia, Missouri, USA;
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36
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Distinct mechanisms regulate exposure of neutralizing epitopes in the V2 and V3 loops of HIV-1 envelope. J Virol 2014; 88:12853-65. [PMID: 25165106 DOI: 10.1128/jvi.02125-14] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Broadly neutralizing antibodies targeting the HIV-1 envelope (Env) are key components for protection against HIV-1. However, many cross-reactive epitopes are often occluded. This study investigates the mechanisms contributing to the masking of V2i (variable loop V2 integrin) epitopes compared to the accessibility of V3 epitopes. V2i are conformation-dependent epitopes encompassing the integrin α4β7-binding motif on the V1V2 loop of HIV-1 Env gp120. The V2i monoclonal antibodies (MAbs) display extensive cross-reactivity with gp120 monomers from many subtypes but neutralize only few viruses, indicating V2i's cryptic nature. First, we asked whether CD4-induced Env conformational changes affect V2i epitopes similarly to V3. CD4 treatment of BaL and JRFL pseudoviruses increased their neutralization sensitivity to V3 MAbs but not to the V2i MAbs. Second, the contribution of N-glycans in masking V2i versus V3 epitopes was evaluated by testing the neutralization of pseudoviruses produced in the presence of a glycosidase inhibitor, kifunensine. Viruses grown in kifunensine were more sensitive to neutralization by V3 but not V2i MAbs. Finally, we evaluated the time-dependent dynamics of the V2i and V3 epitopes. Extending the time of virus-MAb interaction to 18 h before adding target cells increased virus neutralization by some V2i MAbs and all V3 MAbs tested. Consistent with this, V2i MAb binding to Env on the surface of transfected cells also increased in a time-dependent manner. Hence, V2i and V3 epitopes are highly dynamic, but distinct factors modulate the antibody accessibility of these epitopes. The study reveals the importance of the structural dynamics of V2i and V3 epitopes in determining HIV-1 neutralization by antibodies targeting these sites. IMPORTANCE Conserved neutralizing epitopes are present in the V1V2 and V3 regions of HIV-1 Env, but these epitopes are often occluded from Abs. This study reveals that distinct mechanisms contribute to the masking of V3 epitopes and V2i epitopes in the V1V2 domain. Importantly, V3 MAbs and some V2i MAbs display greater neutralization against relatively resistant HIV-1 isolates when the MAbs interact with the virus for a prolonged period of time. Given their highly immunogenic nature, V3 and V2i epitopes are valuable targets that would augment the efficacy of HIV vaccines.
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37
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Manhas S, Chau D, Rempel C, Clark BE, Auyeung K, Pantophlet R. The presence of glutamine at position 315 but not epitope masking predominantly hinders HIV subtype C neutralization by the anti-V3 antibody B4e8. Virology 2014; 462-463:98-106. [PMID: 24971702 PMCID: PMC4125615 DOI: 10.1016/j.virol.2014.05.034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2014] [Revised: 04/14/2014] [Accepted: 05/19/2014] [Indexed: 11/19/2022]
Abstract
Antibody B4e8 exhibits modest cross-neutralizing activity, with preference for HIV subtype B. This preference might be explained by B4e8׳s extensive interaction with Arg315, which occurs at the center of most subtype B V3 sequences but is replaced by Gln in subtype C. The extent to which B4e8׳s ability to neutralize subtype C strains is hindered by Gln315 and/or other factors, e.g. epitope masking, is unclear. We confirmed here that an Arg315-to-Gln substitution in a subtype B virus abrogates B4e8 neutralizing activity. Conversely, B4e8-resistant subtype C viruses were rendered sensitive upon Gln 315-to-Arg substitution. V2 region swapping between B4e8-sensitive and- resistant subtype C strains revealed a role for V2 in limiting B4e8 access, but this was less significant than the absence of Arg315. Our findings, while illustrating the importance of Arg315 for B4e8, suggest that some subtype C strains may be vulnerable to B4e8 derivatives capable of binding stronger to Gln315-containing sequences.
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Affiliation(s)
- Savrina Manhas
- Faculty of Health Sciences, Simon Fraser University, British Columbia, Burnaby, Canada V5A 1S6
| | - Dennis Chau
- Faculty of Health Sciences, Simon Fraser University, British Columbia, Burnaby, Canada V5A 1S6
| | - Caitlin Rempel
- Faculty of Health Sciences, Simon Fraser University, British Columbia, Burnaby, Canada V5A 1S6
| | - Brenda E Clark
- Faculty of Health Sciences, Simon Fraser University, British Columbia, Burnaby, Canada V5A 1S6
| | - Kate Auyeung
- Faculty of Health Sciences, Simon Fraser University, British Columbia, Burnaby, Canada V5A 1S6
| | - Ralph Pantophlet
- Faculty of Health Sciences, Simon Fraser University, British Columbia, Burnaby, Canada V5A 1S6; Department of Molecular Biology and Biochemistry, Simon Fraser University, British Columbia, Burnaby, Canada V5A 1S6.
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38
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Cardozo T, Wang S, Jiang X, Kong XP, Hioe C, Krachmarov C. Vaccine focusing to cross-subtype HIV-1 gp120 variable loop epitopes. Vaccine 2014; 32:4916-24. [PMID: 25045827 DOI: 10.1016/j.vaccine.2014.07.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 06/30/2014] [Accepted: 07/08/2014] [Indexed: 10/25/2022]
Abstract
We designed synthetic, epitope-focused immunogens that preferentially display individual neutralization epitopes targeted by cross-subtype anti-HIV V3 loop neutralizing monoclonal antibodies (mAbs). Vaccination of rabbits with these immunogens resulted in the elicitation of distinct polyclonal serum Abs that exhibit cross-subtype neutralization specificities mimicking the mAbs that guided the design. Our results prove the principle that a predictable range of epitope-specific polyclonal cross-subtype HIV-1 neutralizing Abs can be intentionally elicited in mammals by vaccination. The precise boundaries of the epitopes and conformational flexibility in the presentation of the epitopes in the immunogen appeared to be important for successful elicitation. This work may serve as a starting point for translating the activities of human broadly neutralizing anti-HIV-1 monoclonal antibodies (bNAbs) into matched immunogens that can contribute to an efficacious HIV-1 vaccine.
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Affiliation(s)
- Timothy Cardozo
- New York University School of Medicine, Department of Biochemistry and Molecular Pharmacology, 550 First Avenue, New York, NY 10016, United States.
| | - Shixia Wang
- University of Massachusetts Medical School, Department of Medicine, 364 Plantation Street, Lazare Research Building, Worcester, MA 01605, United States
| | - Xunqing Jiang
- New York University School of Medicine, Department of Biochemistry and Molecular Pharmacology, 550 First Avenue, New York, NY 10016, United States
| | - Xiang-Peng Kong
- New York University School of Medicine, Department of Biochemistry and Molecular Pharmacology, 550 First Avenue, New York, NY 10016, United States
| | - Catarina Hioe
- New York University School of Medicine, Department of Pathology, 550 First Avenue, New York, NY 10016, United States; Veterans Affairs Medical Center, 423 East 23rd Street, New York, NY 10010, United States
| | - Chavdar Krachmarov
- New York University School of Medicine, Department of Biochemistry and Molecular Pharmacology, 550 First Avenue, New York, NY 10016, United States
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Rao M, Peachman KK, Kim J, Gao G, Alving CR, Michael NL, Rao VB. HIV-1 variable loop 2 and its importance in HIV-1 infection and vaccine development. Curr HIV Res 2014; 11:427-38. [PMID: 24191938 DOI: 10.2174/1570162x113116660064] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2013] [Revised: 05/24/2013] [Accepted: 06/13/2013] [Indexed: 12/30/2022]
Abstract
A vaccine that can prevent the transmission of HIV-1 at the site of exposure to the host is one of the best hopes to control the HIV-1 pandemic. The trimeric envelope spike consisting of heterodimers, gp120 and gp41, is essential for virus entry and thus has been a key target for HIV-1 vaccine development. However, it has been extremely difficult to identify the types of antibodies required to block the transmission of various HIV-1 strains and the immunogens that can elicit such antibodies due to the high genetic diversity of the HIV-1 envelope. The modest efficacy of the gp120 HIV-1 vaccine used in the RV144 Thai trial, including the studies on the immune correlates of protection, and the discovery of vaccine-induced immune responses to certain signature regions of the envelope have shown that the gp120 variable loop 2 (V2) is an important region. Since there is evidence that the V2 region interacts with the integrin α4β7 receptor of the host cell, and that this interaction might be important for virus capture, induction of antibodies against V2 loop could be postulated as one of the mechanisms to prevent the acquisition of HIV-1. Immunogens that can induce these antibodies should therefore be taken into consideration when designing HIV-1 vaccine formulations.
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Affiliation(s)
- Mangala Rao
- Laboratory of Adjuvant and Antigen Research, USMHRP at the Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Rm 2A08, Sliver Spring, MD 20910, USA.
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Global panel of HIV-1 Env reference strains for standardized assessments of vaccine-elicited neutralizing antibodies. J Virol 2013; 88:2489-507. [PMID: 24352443 DOI: 10.1128/jvi.02853-13] [Citation(s) in RCA: 234] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
UNLABELLED Standardized assessments of HIV-1 vaccine-elicited neutralizing antibody responses are complicated by the genetic and antigenic variability of the viral envelope glycoproteins (Envs). To address these issues, suitable reference strains are needed that are representative of the global epidemic. Several panels have been recommended previously, but no clear answers have been available on how many and which strains are best suited for this purpose. We used a statistical model selection method to identify a global panel of reference Env clones from among 219 Env-pseudotyped viruses assayed in TZM-bl cells with sera from 205 HIV-1-infected individuals. The Envs and sera were sampled globally from diverse geographic locations and represented all major genetic subtypes and circulating recombinant forms of the virus. Assays with a panel size of only nine viruses adequately represented the spectrum of HIV-1 serum neutralizing activity seen with the larger panel of 219 viruses. An optimal panel of nine viruses was selected and augmented with three additional viruses for greater genetic and antigenic coverage. The spectrum of HIV-1 serum neutralizing activity seen with the final 12-virus panel closely approximated the activity seen with subtype-matched viruses. Moreover, the final panel was highly sensitive for detection of many of the known broadly neutralizing antibodies. For broader assay applications, all 12 Env clones were converted to infectious molecular clones using a proviral backbone carrying a Renilla luciferase reporter gene (Env.IMC.LucR viruses). This global panel should facilitate highly standardized assessments of vaccine-elicited neutralizing antibodies across multiple HIV-1 vaccine platforms in different parts of the world. IMPORTANCE An effective HIV-1 vaccine will need to overcome the extraordinary genetic variability of the virus, where most variation occurs in the viral envelope glycoproteins that are the sole targets for neutralizing antibodies. Efforts to elicit broadly cross-reactive neutralizing antibodies that will protect against infection by most circulating strains of the virus are guided in part by in vitro assays that determine the ability of vaccine-elicited antibodies to neutralize genetically diverse HIV-1 variants. Until now, little information was available on how many and which strains of the virus are best suited for this purpose. We applied robust statistical methods to evaluate a large neutralization data set and identified a small panel of viruses that are a good representation of the global epidemic. The neutralization properties of this new panel of reference strains should facilitate the development of an effective HIV-1 vaccine.
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Andrianov AM, Kashyn IA, Tuzikov AV. Discovery of novel anti-HIV-1 agents based on a broadly neutralizing antibody against the envelope gp120 V3 loop: a computational study. J Biomol Struct Dyn 2013; 32:1993-2004. [DOI: 10.1080/07391102.2013.848825] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Palaia JM, McConnell M, Achenbach JE, Gustafson CE, Stoermer KA, Nolan M, Guay LA, Leitner TK, Matovu F, Taylor AW, Fowler MG, Janoff EN. Neutralization of HIV subtypes A and D by breast milk IgG from women with HIV infection in Uganda. J Infect 2013; 68:264-72. [PMID: 24239588 DOI: 10.1016/j.jinf.2013.11.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 11/01/2013] [Accepted: 11/07/2013] [Indexed: 11/25/2022]
Abstract
OBJECTIVES Among HIV-exposed infants in resource-limited countries, 8-12% are infected postnatally by breastfeeding. However, most of those uninfected at birth remain uninfected over time despite daily exposure to HIV in breast milk. Thus, we assessed the HIV-inhibitory activity of breast milk. METHODS We measured cross-clade neutralization in activated PBMC of Ugandan subtype A (92UG031) and D (92UG005) primary HIV by breast milk or purified milk IgG and IgA from 25 HIV-infected Ugandan women. Isotype-specific antigen recognition was resolved by immunoblot. We determined HIV subtype from envelope population sequences in cells from 13 milk samples by PCR. RESULTS Milk inhibited p24 production by ≥50% (dose-dependent) by subtype A (21/25; 84%) and subtype D (11/25; 44%). IgG consistently reacted with multiple HIV antigens, including gp120/gp41, but IgA primarily recognized p24 alone. Depletion of IgG (n = 5), not IgA, diminished neutralization (mean 78 ± 33%) that was largely restored by IgG repletion. Mothers infected with subtype A more effectively neutralized subtype A than D. CONCLUSIONS Breast milk from HIV-infected women showed homotypic and cross-subtype neutralization of HIV by IgG-dependent and -independent mechanisms. These data direct further investigations into mechanisms of resistance against postnatal transmission of HIV to infants from their mothers.
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Affiliation(s)
- Jana M Palaia
- Mucosal and Vaccine Research Colorado (MAVRC), University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; Denver Veterans Affairs Medical Center, Denver, CO 80220, USA
| | | | - Jenna E Achenbach
- Mucosal and Vaccine Research Colorado (MAVRC), University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Claire E Gustafson
- Mucosal and Vaccine Research Colorado (MAVRC), University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; Denver Veterans Affairs Medical Center, Denver, CO 80220, USA
| | - Kristina A Stoermer
- Mucosal and Vaccine Research Colorado (MAVRC), University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Monica Nolan
- Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
| | - Laura A Guay
- Makerere University - Johns Hopkins University, Kampala, Uganda
| | | | - Flavia Matovu
- Makerere University - Johns Hopkins University, Kampala, Uganda
| | - Allan W Taylor
- Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
| | | | - Edward N Janoff
- Mucosal and Vaccine Research Colorado (MAVRC), University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; Denver Veterans Affairs Medical Center, Denver, CO 80220, USA.
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Specific sequences commonly found in the V3 domain of HIV-1 subtype C isolates affect the overall conformation of native Env and induce a neutralization-resistant phenotype independent of V1/V2 masking. Virology 2013; 448:363-74. [PMID: 24314667 DOI: 10.1016/j.virol.2013.10.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 08/23/2013] [Accepted: 10/03/2013] [Indexed: 11/21/2022]
Abstract
Primary HIV-1 isolates are relatively resistant to neutralization by antibodies commonly induced after infection or vaccination. This is generally attributed to masking of sensitive epitopes by the V1/V2 domain and/or glycans situated at various positions in Env. Here we identified a novel masking effect mediated by subtype C-specific V3 sequences that contributes to the V1/V2-independent and glycan-independent neutralization resistance of chimeric and primary Envs to antibodies directed against multiple neutralization domains. Positions at several conserved charged and hydrophobic sites in the V3 crown and stem were also shown to affect neutralization phenotype. These results indicated that substitutions typically present in subtype C and related V3 sequences influence the overall conformation of native Env in a way that occludes multiple neutralization targets located both within and outside of the V3 domain, and may reflect an alternative mechanism for neutralization resistance that is particularly active in subtype C and related isolates.
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Visciano ML, Tagliamonte M, Stewart-Jones G, Heyndrickx L, Vanham G, Jansson M, Fomsgaard A, Grevstad B, Ramaswamy M, Buonaguro FM, Tornesello ML, Biswas P, Scarlatti G, Buonaguro L. Characterization of humoral responses to soluble trimeric HIV gp140 from a clade A Ugandan field isolate. J Transl Med 2013; 11:165. [PMID: 23835244 PMCID: PMC3729709 DOI: 10.1186/1479-5876-11-165] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 06/20/2013] [Indexed: 11/25/2022] Open
Abstract
Trimeric soluble forms of HIV gp140 envelope glycoproteins represent one of the closest molecular structures compared to native spikes present on intact virus particles. Trimeric soluble gp140 have been generated by several groups and such molecules have been shown to induce antibodies with neutralizing activity against homologous and heterologous viruses. In the present study, we generated a recombinant trimeric soluble gp140, derived from a previously identified Ugandan A-clade HIV field isolate (gp14094UG018). Antibodies elicited in immunized rabbits show a broad binding pattern to HIV envelopes of different clades. An epitope mapping analysis reveals that, on average, the binding is mostly focused on the C1, C2, V3, V5 and C5 regions. Immune sera show neutralization activity to Tier 1 isolates of different clades, demonstrating cross clade neutralizing activity which needs to be further broadened by possible structural modifications of the clade A gp14094UG018. Our results provide a rationale for the design and evaluation of immunogens and the clade A gp14094UG018 shows promising characteristics for potential involvement in an effective HIV vaccine with broad activity.
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Affiliation(s)
- Maria Luisa Visciano
- Molecular Biology and Viral Oncogenesis Unit, Department of Experimental Oncology, Istituto Nazionale per lo Studio e la Cura dei Tumori "Fondazione Pascale" - IRCCS, Naples, Italy
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Andrabi R, Williams C, Wang XH, Li L, Choudhary AK, Wig N, Biswas A, Luthra K, Nadas A, Seaman MS, Nyambi P, Zolla-Pazner S, Gorny MK. Cross-neutralizing activity of human anti-V3 monoclonal antibodies derived from non-B clade HIV-1 infected individuals. Virology 2013; 439:81-8. [PMID: 23466102 DOI: 10.1016/j.virol.2012.12.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 12/06/2012] [Accepted: 12/14/2012] [Indexed: 01/04/2023]
Abstract
One approach to the development of an HIV vaccine is to design a protein template which can present gp120 epitopes inducing cross-neutralizing antibodies. To select a V3 sequence for immunogen design, we compared the neutralizing activities of 18 anti-V3 monoclonal antibodies (mAbs) derived from Cameroonian and Indian individuals infected with clade AG and C, respectively. It was found that V3 mAbs from the Cameroonian patients were significantly more cross-neutralizing than those from India. Interestingly, superior neutralizing activity of Cameroonian mAbs was also observed among the nine VH5-51/VL lambda genes encoding V3 mAbs which mediate a similar mode of recognition. This correlated with higher relative binding affinity to a variety of gp120s and increased mutation rates in V3 mAbs from Cameroon. These results suggest that clade C V3 is probably weakly immunogenic and that the V3 sequence of CRF02_AG viruses can serve as a plausible template for vaccine immunogen design.
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Affiliation(s)
- Raiees Andrabi
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
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Antibody-DEPENDENT, FcγRI-mediated neutralization of HIV-1 in TZM-bl cells occurs independently of phagocytosis. J Virol 2013; 87:5287-90. [PMID: 23408628 DOI: 10.1128/jvi.00278-13] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We previously showed that expression of human FcγRI on TZM-bl cells potentiates neutralization by gp41 membrane-proximal external region (MPER)-specific antibodies. Here we show that lysosomotropic reagents known to block phagocytosis do not diminish this effect. We also show that FcγRI occasionally potentiates neutralization by antibodies against the V3 loop of gp120 and cluster I of gp41. We conclude that FcγRI provides a kinetic advantage for neutralizing antibodies against partially cryptic epitopes independent of phagocytosis.
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Abstract
A fascinating aspect of viral evolution relates to the ability of viruses to escape the adaptive immune response. The widely held view has been that the great variability of viral glycoproteins would be an absolute obstacle to the development of antibody-based therapies or vaccines that could confer broad and long-lasting protection. In the past five years, new approaches have been developed to interrogate human memory B cells and plasma cells with high efficiency and to isolate several broadly neutralizing antiviral antibodies against highly variable pathogens such as HIV-1 and influenza virus. These antibodies not only provide new tools for prophylaxis and therapy for viral diseases but also identify conserved epitopes that may be used to design new vaccines capable of conferring broader protection.
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Affiliation(s)
- Davide Corti
- Institute for Research in Biomedicine IRB, 6500 Bellinzona, Switzerland.
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Kumar R, Andrabi R, Tiwari A, Prakash SS, Wig N, Dutta D, Sankhyan A, Khan L, Sinha S, Luthra K. A novel strategy for efficient production of anti-V3 human scFvs against HIV-1 clade C. BMC Biotechnol 2012; 12:87. [PMID: 23153214 PMCID: PMC3536577 DOI: 10.1186/1472-6750-12-87] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 10/17/2012] [Indexed: 11/10/2022] Open
Abstract
Background Production of human monoclonal antibodies that exhibit broadly neutralizing activity is needed for preventing HIV-1 infection, however only a few such antibodies have been generated till date. Isolation of antibodies by the hybridoma technology is a cumbersome process with fewer yields. Further, the loss of unstable or slowly growing clones which may have unique binding specificities often occurs during cloning and propagation and the strongly positive clones are often lost. This has been avoided by the process described in this paper, wherein, by combining the strategy of EBV transformation and recombinant DNA technology, we constructed human single chain variable fragments (scFvs) against the third variable region (V3) of the clade C HIV-1 envelope. Results An antigen specific phage library of 7000 clones was constructed from the enriched V3- positive antibody secreting EBV transformed cells. By ligation of the digested scFv DNA into phagemid vector and bio panning against the HIV-1 consensus C and B V3 peptides followed by random selection of 40 clones, we identified 15 clones that showed V3 reactivity in phage ELISA. DNA fingerprinting analysis and sequencing showed that 13 out of the 15 clones were distinct. Expression of the positive clones was tested by SDS-PAGE and Western blot. All the 13 anti-V3 scFvs showed cross-reactivity against both the clade C and B V3 peptides and did not show any reactivity against other unrelated peptides in ELISA. Preliminary neutralization assays indicated varying degrees of neutralization of clade C and B viruses. EBV transformation, followed by antigen selection of lines to identify specific binders, enabled the selection of phage from un-cloned lines for scFv generation, thus avoiding the problems of hybridoma technology. Moreover, as the clones were pretested for antigen binding, a comparatively small library sufficed for the selection of a considerable number of unique antigen binding phage. After selection, the phage clones were propagated in a clonal manner. Conclusions This strategy can be efficiently used and is cost effective for the generation of diverse recombinant antibodies. This is the first study to generate anti-V3 scFvs against HIV-1 Clade C.
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Affiliation(s)
- Rajesh Kumar
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India
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Abstract
PURPOSE OF REVIEW New findings continue to support the notion that broadly crossreactive neutralizing antibody induction is a worthwhile and achievable goal for HIV-1 vaccines. Immunogens are needed that can overcome the genetic variability and complex immune evasion tactics of the virus. Other antibodies might bridge innate and acquired immunity for possible beneficial vaccine effects. This review summarizes progress made over the past year that has enhanced our understanding of humoral immunity as it relates to HIV-1 vaccine development. RECENT FINDINGS Although a clear path to designing an effective neutralizing antibody-based HIV-1 vaccine remains elusive, there is new information on how antibodies neutralize HIV-1, the epitopes involved, and clues to the possible nature of protective immunogens that keep this goal alive. Moreover, there is a greater understanding of HIV-1 diversity and its possible limits under immune pressure. Other antibodies might possess antiviral activity by mechanisms involving Fc receptor engagement or complement activation that would be of value for HIV-1 vaccines. SUMMARY Recent developments strengthen the rationale for antibody-based HIV-1 vaccine immunogens and provide a stronger foundation for vaccine discovery.
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Andrabi R, Kumar R, Bala M, Nair A, Biswas A, Wig N, Kumar P, Pal R, Sinha S, Luthra K. Production and characterization of human anti-V3 monoclonal antibodies from the cells of HIV-1 infected Indian donors. Virol J 2012; 9:196. [PMID: 22971578 PMCID: PMC3493341 DOI: 10.1186/1743-422x-9-196] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 08/29/2012] [Indexed: 01/10/2023] Open
Abstract
Background Analysis of human monoclonal antibodies (mAbs) developed from HIV-1 infected donors have enormously contributed to the identification of neutralization sensitive epitopes on the HIV-1 envelope glycoprotein. The third variable region (V3) is a crucial target on gp120, primarily due to its involvement in co-receptor (CXCR4 or CCR5) binding and presence of epitopes recognized by broadly neutralizing antibodies. Methods Thirty-three HIV-1 seropositive drug naive patients (18 males and 15 females) within the age range of 20–57 years (median = 33 years) were recruited in this study for mAb production. The mAbs were selected from EBV transformed cultures with conformationally constrained Cholera-toxin-B containing V3C (V3C-CTB) fusion protein. We tested the mAbs for their binding with HIV-1 derived proteins and peptides by ELISA and for neutralization against HIV-1 viruses by TZM-bl assays. Results We isolated three anti-V3 mAbs, 277, 903 and 904 from the cells of different individuals. The ELISA binding revealed a subtype-C and subtype-A specific binding of antibody 277 and 903 while mAb 904 exhibited cross reactivity also with subtype-B V3. Epitope mapping of mAbs with overlapping V3 peptides showed exclusive binding to V3 crown. The antibodies displayed high and low neutralizing activity against 2/5 tier 1 and 1/6 tier 2 viruses respectively. Overall, we observed a resistance of the tier 2 viruses to neutralization by the anti-V3 mAbs, despite the exposure of the epitopes recognized by these antibodies on two representative native viruses (Du156.12 and JRFL), suggesting that the affinity of mAb might equally be crucial for neutralization, as the epitope recognition. Conclusions Our study suggests that the anti-V3 antibodies derived from subtype-C infected Indian patients display neutralization potential against tier 1 viruses while such activity may be limited against more resistant tier 2 viruses. Defining the fine epitope specificities of these mAbs and further experimental manipulations will be helpful in identification of epitopes, unique to clade C or shared with non-clade C viruses, in context of V3 region.
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Affiliation(s)
- Raiees Andrabi
- Department of Biochemistry, All India Institute of Medical Sciences (AIIMS), New Delhi, India
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