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Wei Z, Angrisano F, Eriksson EM, Mazhari R, Van H, Zheng S, Center RJ, Boo I, McMahon J, Lau J, Kiernan‐Walker N, Ruybal‐Pesántez S, Mueller I, Robinson LJ, Anderson DA, Drummer HE. Serological assays to measure dimeric IgA antibodies in SARS-CoV-2 infections. Immunol Cell Biol 2023; 101:857-866. [PMID: 37593973 PMCID: PMC10952984 DOI: 10.1111/imcb.12682] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 05/22/2023] [Accepted: 08/01/2023] [Indexed: 08/19/2023]
Abstract
Current serological tests cannot differentiate between total immunoglobulin A (IgA) and dimeric IgA (dIgA) associated with mucosal immunity. Here, we describe two new assays, dIgA-ELISA and dIgA-multiplex bead assay (MBA), that utilize the preferential binding of dIgA to a chimeric form of secretory component, allowing the differentiation between dIgA and monomeric IgA. dIgA responses elicited through severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection were measured in (i) a longitudinal panel, consisting of 74 samples (n = 20 individuals) from hospitalized cases of coronavirus disease 2019 (COVID-19); (ii) a longitudinal panel, consisting of 96 samples (n = 10 individuals) from individuals with mild COVID-19; (iii) a cross-sectional panel with PCR-confirmed SARS-CoV-2 infection with mild COVID-19 (n = 199) and (iv) pre-COVID-19 samples (n = 200). The dIgA-ELISA and dIgA-MBA demonstrated a specificity for dIgA of 99% and 98.5%, respectively. Analysis of dIgA responses in the longitudinal panels revealed that 70% (ELISA) and 50% (MBA) of patients elicited a dIgA response by day 20 after PCR diagnosis with a SARS-CoV-2 infection. Individuals with mild COVID-19 displayed increased levels of dIgA within the first 3 weeks after diagnosis but responses appeared to be short lived, compared with sustained IgA levels. However, in samples from hospitalized patients with COVID-19 we observed high and sustained levels of dIgA, up to 245 days after PCR diagnosis. Our results suggest that severe COVID-19 infections are associated with sustained levels of plasma dIgA compared with mild cases.
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Affiliation(s)
- Zihui Wei
- Burnet Institute, 85 Commercial RoadDepartment of Life SciencesMelbourneVIC3004Australia
| | - Fiona Angrisano
- Burnet Institute, 85 Commercial RoadDepartment of Life SciencesMelbourneVIC3004Australia
| | - Emily M Eriksson
- Walter and Eliza Hall Institute of Medical Research Department of Population Health and ImmunityParkvilleVIC3052Australia
- The University of MelbourneDepartment of Medical BiologyParkvilleVIC3052Australia
| | - Ramin Mazhari
- Walter and Eliza Hall Institute of Medical Research Department of Population Health and ImmunityParkvilleVIC3052Australia
- The University of MelbourneDepartment of Medical BiologyParkvilleVIC3052Australia
| | - Huy Van
- Burnet Institute, 85 Commercial RoadDepartment of Life SciencesMelbourneVIC3004Australia
| | - Shuning Zheng
- Burnet Institute, 85 Commercial RoadDepartment of Life SciencesMelbourneVIC3004Australia
| | - Rob J Center
- Burnet Institute, 85 Commercial RoadDepartment of Life SciencesMelbourneVIC3004Australia
- Peter Doherty Institute for Infection and Immunity at The University of MelbourneParkvilleVIC3052Australia
| | - Irene Boo
- Burnet Institute, 85 Commercial RoadDepartment of Life SciencesMelbourneVIC3004Australia
| | - James McMahon
- Monash UniversityDepartment of Infectious Diseases Alfred HealthMelbourneVIC3004Australia
| | - Jillian Lau
- Peter Doherty Institute for Infection and Immunity at The University of MelbourneParkvilleVIC3052Australia
- Monash UniversityDepartment of Infectious Diseases Alfred HealthMelbourneVIC3004Australia
| | - Nicholas Kiernan‐Walker
- Walter and Eliza Hall Institute of Medical Research Department of Population Health and ImmunityParkvilleVIC3052Australia
| | - Shazia Ruybal‐Pesántez
- Burnet Institute, 85 Commercial RoadDepartment of Life SciencesMelbourneVIC3004Australia
- Walter and Eliza Hall Institute of Medical Research Department of Population Health and ImmunityParkvilleVIC3052Australia
- The University of MelbourneDepartment of Medical BiologyParkvilleVIC3052Australia
| | - Ivo Mueller
- Walter and Eliza Hall Institute of Medical Research Department of Population Health and ImmunityParkvilleVIC3052Australia
| | - Leanne J Robinson
- Burnet Institute, 85 Commercial RoadDepartment of Life SciencesMelbourneVIC3004Australia
- Walter and Eliza Hall Institute of Medical Research Department of Population Health and ImmunityParkvilleVIC3052Australia
| | - David A Anderson
- Burnet Institute, 85 Commercial RoadDepartment of Life SciencesMelbourneVIC3004Australia
| | - Heidi E Drummer
- Burnet Institute, 85 Commercial RoadDepartment of Life SciencesMelbourneVIC3004Australia
- Peter Doherty Institute for Infection and Immunity at The University of MelbourneParkvilleVIC3052Australia
- Monash UniversityDepartment of MicrobiologyClaytonVIC3168Australia
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2
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Poumbourios P, Langer C, Boo I, Zakir T, Center RJ, Akerman A, Milogiannakis V, Aggarwal A, Johnstone BA, Ha J, Coulibaly F, Turville SG, Drummer HE. Enhanced stability of the SARS CoV-2 spike glycoprotein following modification of an alanine cavity in the protein core. PLoS Pathog 2023; 19:e1010981. [PMID: 37200378 PMCID: PMC10231827 DOI: 10.1371/journal.ppat.1010981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 05/31/2023] [Accepted: 04/24/2023] [Indexed: 05/20/2023] Open
Abstract
The spike (S) glycoprotein of SARS CoV-2 is the target of neutralizing antibodies (NAbs) that are crucial for vaccine effectiveness. The S1 subunit binds ACE2 while the S2 subunit mediates virus-cell membrane fusion. S2 is a class I fusion glycoprotein subunit and contains a central coiled coil that acts as a scaffold for the conformational changes associated with fusion function. The coiled coil of S2 is unusual in that the 3-4 repeat of inward-facing positions are mostly occupied by polar residues that mediate few inter-helical contacts in the prefusion trimer. We examined how insertion of bulkier hydrophobic residues (Val, Leu, Ile, Phe) to fill a cavity next to Ala1016 and Ala1020 in the 3-4 repeat affects the stability and antigenicity of S trimers. Substitution of Ala1016 with bulkier hydrophobic residues in the context of a prefusion-stabilized S trimer, S2P-FHA, was associated with increased thermal stability. S glycoprotein membrane fusion function was retained with Ala1016/Ala1020 cavity-filling mutations associated with improved recombinant S2P-FHA thermostability, however 2 mutants, A1016L and A1016V/A1020I, lacked ability to mediate entry of S-HIV-1 pseudoparticles into 293-ACE2 cells. When assessed as immunogens, two thermostable S2P-FHA mutants derived from the ancestral isolate, A1016L (16L) and A1016V/A1020I (VI) elicited neutralizing antibody with 50%-inhibitory dilutions (ID50s) in the range 2,700-5,110 for ancestral and Delta-derived viruses, and 210-1,744 for Omicron BA.1. The antigens elicited antibody specificities directed to the receptor-binding domain (RBD), N-terminal domain (NTD), fusion peptide and stem region of S2. The VI mutation enabled the production of intrinsically stable Omicron BA.1 and Omicron BA.4/5 S2P-FHA-like ectodomain oligomers in the absence of an external trimerization motif (T4 foldon), thus representing an alternative approach for stabilizing oligomeric S glycoprotein vaccines.
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Affiliation(s)
- Pantelis Poumbourios
- Burnet Institute, Melbourne, Australia
- Department of Microbiology, Monash University, Clayton, Australia
| | | | - Irene Boo
- Burnet Institute, Melbourne, Australia
| | | | - Rob J. Center
- Burnet Institute, Melbourne, Australia
- Department of Microbiology at The Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Parkville, Australia
| | - Anouschka Akerman
- Kirby Institute, University of New South Wales, Kensington, Australia
| | | | - Anupriya Aggarwal
- Kirby Institute, University of New South Wales, Kensington, Australia
| | - Bronte A. Johnstone
- Infection Program, Biomedicine Discovery Institute, Monash University, Clayton, Australia
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
| | - Jungmin Ha
- Infection Program, Biomedicine Discovery Institute, Monash University, Clayton, Australia
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
| | - Fasséli Coulibaly
- Infection Program, Biomedicine Discovery Institute, Monash University, Clayton, Australia
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
| | | | - Heidi E. Drummer
- Burnet Institute, Melbourne, Australia
- Department of Microbiology, Monash University, Clayton, Australia
- Department of Microbiology at The Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Parkville, Australia
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3
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Donnison T, McGregor J, Chinnakannan S, Hutchings C, Center RJ, Poumbourios P, Klenerman P, Drummer HE, Barnes E. A pan-genotype hepatitis C virus viral vector vaccine generates T cells and neutralizing antibodies in mice. Hepatology 2022; 76:1190-1202. [PMID: 35313015 PMCID: PMC9790311 DOI: 10.1002/hep.32470] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 03/10/2022] [Accepted: 03/14/2022] [Indexed: 02/06/2023]
Abstract
BACKGROUND AND AIMS A prophylactic vaccine targeting multiple HCV genotypes (gt) is urgently required to meet World Health Organization elimination targets. Neutralizing antibodies (nAbs) and CD4+ and CD8+ T cells are associated with spontaneous clearance of HCV, and each may contribute to protective immunity. However, current vaccine candidates generate either nAbs or T cells targeting genetically variable epitopes and have failed to show efficacy in human trials. We have previously shown that a simian adenovirus vector (ChAdOx1) encoding conserved sequences across gt1-6 (ChAd-Gt1-6), and separately gt-1a E2 protein with variable regions deleted (E2Δ123HMW ), generates pan-genotypic T cells and nAbs, respectively. We now aim to develop a vaccine to generate both viral-specific B- and T-cell responses concurrently. APPROACH AND RESULTS We show that vaccinating with ChAd-Gt1-6 and E2Δ123HMW sequentially in mice generates T-cell and antibody (Ab) responses comparable to either vaccine given alone. We encoded E2Δ123 in ChAdOx1 (ChAd-E2Δ123) and show that this, given with an E2Δ123HMW protein boost, induces greater CD81-E2 inhibitory and HCV-pseudoparticle nAb titers compared to the E2Δ123HMW prime boost. We developed bivalent viral vector vaccines (ChAdOx1 and modified vaccinia Ankara [MVA]) encoding both Gt1-6 and E2Δ123 immunogens (Gt1-6-E2Δ123) generating polyfunctional CD4+ and CD8+ T cells and nAb titers in prime/boost strategies. This approach generated nAb responses comparable to monovalent E2Δ123 ChAd/MVA vaccines and superior to three doses of recombinant E2Δ123HMW protein, while also generating high-magnitude T-cell responses. CONCLUSIONS These data are an important step forward for the development of a pan-genotype HCV vaccine to elicit T cells and nAbs for future assessment in humans.
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Affiliation(s)
- Timothy Donnison
- Nuffield Department of Medicine, Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, UK
| | - Joey McGregor
- Burnet Institute, Melbourne, Victoria, Australia.,Department of Microbiology and Immunology at The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, Victoria, Australia
| | - Senthil Chinnakannan
- Nuffield Department of Medicine, Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, UK
| | - Claire Hutchings
- Nuffield Department of Medicine, Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, UK
| | - Rob J Center
- Burnet Institute, Melbourne, Victoria, Australia.,Department of Microbiology and Immunology at The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, Victoria, Australia
| | - Pantelis Poumbourios
- Burnet Institute, Melbourne, Victoria, Australia.,Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Paul Klenerman
- Nuffield Department of Medicine, Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, UK
| | - Heidi E Drummer
- Burnet Institute, Melbourne, Victoria, Australia.,Department of Microbiology and Immunology at The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, Victoria, Australia.,Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Eleanor Barnes
- Nuffield Department of Medicine, Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, UK.,Nuffield Department of Medicine, Jenner Institute, University of Oxford, Oxford, UK
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4
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Fulford TS, Van H, Gherardin NA, Zheng S, Ciula M, Drummer HE, Redmond S, Tan HX, Boo I, Center RJ, Li F, Grimley SL, Wines BD, Nguyen THO, Mordant FL, Ellenberg P, Rowntree LC, Kedzierski L, Cheng AC, Doolan DL, Matthews G, Bond K, Hogarth PM, McQuilten Z, Subbarao K, Kedzierska K, Juno JA, Wheatley AK, Kent SJ, Williamson DA, Purcell DFJ, Anderson DA, Godfrey DI. A point-of-care lateral flow assay for neutralising antibodies against SARS-CoV-2. EBioMedicine 2021; 74:103729. [PMID: 34871960 PMCID: PMC8641961 DOI: 10.1016/j.ebiom.2021.103729] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 11/12/2021] [Accepted: 11/18/2021] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND As vaccines against SARS-CoV-2 are now being rolled out, a better understanding of immunity to the virus, whether from infection, or passive or active immunisation, and the durability of this protection is required. This will benefit from the ability to measure antibody-based protection to SARS-CoV-2, ideally with rapid turnaround and without the need for laboratory-based testing. METHODS We have developed a lateral flow POC test that can measure levels of RBD-ACE2 neutralising antibody (NAb) from whole blood, with a result that can be determined by eye or quantitatively on a small instrument. We compared our lateral flow test with the gold-standard microneutralisation assay, using samples from convalescent and vaccinated donors, as well as immunised macaques. FINDINGS We show a high correlation between our lateral flow test with conventional neutralisation and that this test is applicable with animal samples. We also show that this assay is readily adaptable to test for protection to newly emerging SARS-CoV-2 variants, including the beta variant which revealed a marked reduction in NAb activity. Lastly, using a cohort of vaccinated humans, we demonstrate that our whole-blood test correlates closely with microneutralisation assay data (specificity 100% and sensitivity 96% at a microneutralisation cutoff of 1:40) and that fingerprick whole blood samples are sufficient for this test. INTERPRETATION Taken together, the COVID-19 NAb-testTM device described here provides a rapid readout of NAb based protection to SARS-CoV-2 at the point of care. FUNDING Support was received from the Victorian Operational Infrastructure Support Program and the Australian Government Department of Health. This work was supported by grants from the Department of Health and Human Services of the Victorian State Government; the ARC (CE140100011, CE140100036), the NHMRC (1113293, 2002317 and 1116530), and Medical Research Future Fund Awards (2005544, 2002073, 2002132). Individual researchers were supported by an NHMRC Emerging Leadership Level 1 Investigator Grants (1194036), NHMRC APPRISE Research Fellowship (1116530), NHMRC Leadership Investigator Grant (1173871), NHMRC Principal Research Fellowship (1137285), NHMRC Investigator Grants (1177174 and 1174555) and NHMRC Senior Principal Research Fellowships (1117766 and 1136322). Grateful support was also received from the A2 Milk Company and the Jack Ma Foundation.
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Affiliation(s)
- Thomas S Fulford
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Huy Van
- Burnet Institute, Melbourne, Victoria, Australia
| | - Nicholas A Gherardin
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia; Australian Research Council Centre of Excellence in Advanced Molecular Imaging, University of Melbourne, Melbourne, Victoria, Australia
| | | | - Marcin Ciula
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Heidi E Drummer
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia; Burnet Institute, Melbourne, Victoria, Australia; Department of Microbiology, Monash University, Australia
| | - Samuel Redmond
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Hyon-Xhi Tan
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Irene Boo
- Burnet Institute, Melbourne, Victoria, Australia
| | - Rob J Center
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia; Burnet Institute, Melbourne, Victoria, Australia
| | - Fan Li
- Burnet Institute, Melbourne, Victoria, Australia
| | - Samantha L Grimley
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Bruce D Wines
- Immune therapies Laboratory, Burnet Institute, Melbourne, VIC, Australia,; Department of Immunology and Pathology, Central Clinical School, Monash University, Melbourne, VIC, Australia; Department of Clinical Pathology, The University of Melbourne, Parkville, VIC, Australia
| | - Thi H O Nguyen
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Francesca L Mordant
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Paula Ellenberg
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Louise C Rowntree
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Lukasz Kedzierski
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Allen C Cheng
- Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia
| | - Denise L Doolan
- Australian Institute of Tropical Health & Medicine, James Cook University, Cairns, Queensland, Australia
| | - Gail Matthews
- Kirby Institute, University of NSW, Sydney, NSW, Australia
| | - Katherine Bond
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia; Department of Microbiology, Royal Melbourne Hospital, Melbourne, Australia
| | - P Mark Hogarth
- Immune therapies Laboratory, Burnet Institute, Melbourne, VIC, Australia,; Department of Immunology and Pathology, Central Clinical School, Monash University, Melbourne, VIC, Australia; Department of Clinical Pathology, The University of Melbourne, Parkville, VIC, Australia
| | - Zoe McQuilten
- Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia
| | - Kanta Subbarao
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia; WHO Collaborating Centre for Reference and Research on Influenza at the Peter Doherty Institute for Infection and Immunity
| | - Katherine Kedzierska
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Jennifer A Juno
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Adam K Wheatley
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia; Melbourne Sexual Health Centre and Department of Infectious Diseases, Alfred Hospital and Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - Stephen J Kent
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia; Melbourne Sexual Health Centre and Department of Infectious Diseases, Alfred Hospital and Central Clinical School, Monash University, Melbourne, Victoria, Australia; Australian Research Council Centre for Excellence in Convergent Bio-Nano Science and Technology, University of Melbourne, Melbourne, Victoria, Australia
| | - Deborah A Williamson
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia; Department of Microbiology, Royal Melbourne Hospital, Melbourne, Australia
| | - Damian F J Purcell
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | | | - Dale I Godfrey
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia; Australian Research Council Centre of Excellence in Advanced Molecular Imaging, University of Melbourne, Melbourne, Victoria, Australia.
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5
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Drummer HE, Van H, Klock E, Zheng S, Wei Z, Boo I, Center RJ, Li F, Bhat P, Ffrench R, Lau JS, McMahon J, Laeyendecker O, Fernandez RE, Manabe YC, Klein SL, Quinn TC, Anderson DA. Dimeric IgA is a specific biomarker of recent SARS-CoV-2 infection. medRxiv 2021:2021.06.28.21259671. [PMID: 34230936 PMCID: PMC8259913 DOI: 10.1101/2021.06.28.21259671] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Current tests for SARS-CoV-2 antibodies (IgG, IgM, IgA) cannot differentiate recent and past infections. We describe a point of care, lateral flow assay for SARS-CoV-2 dIgA based on the highly selective binding of dIgA to a chimeric form of secretory component (CSC), that distinguishes dIgA from monomeric IgA. Detection of specific dIgA uses a complex of biotinylated SARS-CoV-2 receptor binding domain and streptavidin-colloidal gold. SARS-CoV-2-specific dIgA was measured both in 112 cross-sectional samples and a longitudinal panel of 362 plasma samples from 45 patients with PCR-confirmed SARS-CoV-2 infection, and 193 discrete pre-COVID-19 or PCR-negative patient samples. The assay demonstrated 100% sensitivity from 11 days post-symptom onset, and a specificity of 98.2%. With an estimated half-life of 6.3 days, dIgA provides a unique biomarker for the detection of recent SARS-CoV-2 infections with potential to enhance diagnosis and management of COVID-19 at point-of-care.
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6
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Feng G, Wines BD, Kurtovic L, Chan JA, Boeuf P, Mollard V, Cozijnsen A, Drew DR, Center RJ, Marshall DL, Chishimba S, McFadden GI, Dent AE, Chelimo K, Boyle MJ, Kazura JW, Hogarth PM, Beeson JG. Mechanisms and targets of Fcγ-receptor mediated immunity to malaria sporozoites. Nat Commun 2021; 12:1742. [PMID: 33741975 PMCID: PMC7979888 DOI: 10.1038/s41467-021-21998-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 02/24/2021] [Indexed: 12/19/2022] Open
Abstract
A highly protective vaccine will greatly facilitate achieving and sustaining malaria elimination. Understanding mechanisms of antibody-mediated immunity is crucial for developing vaccines with high efficacy. Here, we identify key roles in humoral immunity for Fcγ-receptor (FcγR) interactions and opsonic phagocytosis of sporozoites. We identify a major role for neutrophils in mediating phagocytic clearance of sporozoites in peripheral blood, whereas monocytes contribute a minor role. Antibodies also promote natural killer cell activity. Mechanistically, antibody interactions with FcγRIII appear essential, with FcγRIIa also required for maximum activity. All regions of the circumsporozoite protein are targets of functional antibodies against sporozoites, and N-terminal antibodies have more activity in some assays. Functional antibodies are slowly acquired following natural exposure to malaria, being present among some exposed adults, but uncommon among children. Our findings reveal targets and mechanisms of immunity that could be exploited in vaccine design to maximize efficacy.
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Affiliation(s)
- Gaoqian Feng
- Burnet Institute for Medical Research and Public Health, Melbourne, VIC, Australia
- Department of Medicine and Doherty Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - Bruce D Wines
- Burnet Institute for Medical Research and Public Health, Melbourne, VIC, Australia
- Central Clinical School, Monash University, Melbourne, VIC, Australia
- Department of Clinical Pathology, The University of Melbourne, Melbourne, VIC, Australia
| | - Liriye Kurtovic
- Burnet Institute for Medical Research and Public Health, Melbourne, VIC, Australia
- Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Jo-Anne Chan
- Burnet Institute for Medical Research and Public Health, Melbourne, VIC, Australia
- Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Philippe Boeuf
- Burnet Institute for Medical Research and Public Health, Melbourne, VIC, Australia
- Department of Medicine and Doherty Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - Vanessa Mollard
- School of BioSciences, The University of Melbourne, Melbourne, VIC, Australia
| | - Anton Cozijnsen
- School of BioSciences, The University of Melbourne, Melbourne, VIC, Australia
| | - Damien R Drew
- Burnet Institute for Medical Research and Public Health, Melbourne, VIC, Australia
| | - Rob J Center
- Burnet Institute for Medical Research and Public Health, Melbourne, VIC, Australia
- Department of Medicine and Doherty Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - Daniel L Marshall
- Burnet Institute for Medical Research and Public Health, Melbourne, VIC, Australia
- Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Sandra Chishimba
- Burnet Institute for Medical Research and Public Health, Melbourne, VIC, Australia
- Department of Medicine and Doherty Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - Geoffrey I McFadden
- School of BioSciences, The University of Melbourne, Melbourne, VIC, Australia
| | - Arlene E Dent
- Centre for Global Health and Diseases, Case Western Reserve University, Cleveland, OH, USA
| | - Kiprotich Chelimo
- Department of Biomedical Science and Technology, Maseno University, Kisumu, Kenya
| | - Michelle J Boyle
- Burnet Institute for Medical Research and Public Health, Melbourne, VIC, Australia
- Department of Immunology, IMR-Berghofer Institute, Herston, QLD, Australia
| | - James W Kazura
- Centre for Global Health and Diseases, Case Western Reserve University, Cleveland, OH, USA
| | - P Mark Hogarth
- Burnet Institute for Medical Research and Public Health, Melbourne, VIC, Australia
- Central Clinical School, Monash University, Melbourne, VIC, Australia
- Department of Clinical Pathology, The University of Melbourne, Melbourne, VIC, Australia
| | - James G Beeson
- Burnet Institute for Medical Research and Public Health, Melbourne, VIC, Australia.
- Department of Medicine and Doherty Institute, The University of Melbourne, Melbourne, VIC, Australia.
- Central Clinical School, Monash University, Melbourne, VIC, Australia.
- Department of Microbiology, Monash University, Melbourne, VIC, Australia.
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7
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Center RJ, Boo I, Phu L, McGregor J, Poumbourios P, Drummer HE. Enhancing the antigenicity and immunogenicity of monomeric forms of hepatitis C virus E2 for use as a preventive vaccine. J Biol Chem 2020; 295:7179-7192. [PMID: 32299914 PMCID: PMC7247312 DOI: 10.1074/jbc.ra120.013015] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 04/13/2020] [Indexed: 12/13/2022] Open
Abstract
The E2 glycoprotein of hepatitis C virus (HCV) is the major target of broadly neutralizing antibodies (bNAbs) that are critical for the efficacy of a prophylactic HCV vaccine. We previously showed that a cell culture-derived, disulfide-linked high-molecular-weight (HMW) form of the E2 receptor-binding domain lacking three variable regions, Δ123-HMW, elicits broad neutralizing activity against the seven major genotypes of HCV. A limitation to the use of this antigen is that it is produced only at low yields and does not have a homogeneous composition. Here, we employed a sequential reduction and oxidation strategy to efficiently refold two high-yielding monomeric E2 species, D123 and a disulfide-minimized version (D123A7), into disulfide-linked HMW-like species (Δ123r and Δ123A7r). These proteins exhibited normal reactivity to bNAbs with continuous epitopes on the neutralizing face of E2, but reduced reactivity to conformation-dependent bNAbs and nonneutralizing antibodies (non-NAbs) compared with the corresponding monomeric species. Δ123r and Δ123A7r recapitulated the immunogenic properties of cell culture-derived D123-HMW in guinea pigs. The refolded antigens elicited antibodies that neutralized homologous and heterologous HCV genotypes, blocked the interaction between E2 and its cellular receptor CD81, and targeted the AS412, AS434, and AR3 domains. Of note, antibodies directed to epitopes overlapping with those of non-NAbs were absent. The approach to E2 antigen engineering outlined here provides an avenue for the development of preventive HCV vaccine candidates that induce bNAbs at higher yield and lower cost.
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Affiliation(s)
- Rob J Center
- Burnet Institute, 85 Commercial Road, Melbourne 3004, Australia; Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne 3000, Australia
| | - Irene Boo
- Burnet Institute, 85 Commercial Road, Melbourne 3004, Australia
| | - Lilian Phu
- Burnet Institute, 85 Commercial Road, Melbourne 3004, Australia; Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne 3000, Australia
| | - Joey McGregor
- Burnet Institute, 85 Commercial Road, Melbourne 3004, Australia; Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne 3000, Australia
| | - Pantelis Poumbourios
- Burnet Institute, 85 Commercial Road, Melbourne 3004, Australia; Department of Microbiology, Monash University, Clayton 3056, Australia
| | - Heidi E Drummer
- Burnet Institute, 85 Commercial Road, Melbourne 3004, Australia; Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne 3000, Australia; Department of Microbiology, Monash University, Clayton 3056, Australia.
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8
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King HAD, Gonelli CA, Tullett KM, Lahoud MH, Purcell DFJ, Drummer HE, Poumbourios P, Center RJ. Conjugation of an scFab domain to the oligomeric HIV envelope protein for use in immune targeting. PLoS One 2019; 14:e0220986. [PMID: 31430333 PMCID: PMC6701830 DOI: 10.1371/journal.pone.0220986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 07/28/2019] [Indexed: 11/19/2022] Open
Abstract
A promising strategy for the enhancement of vaccine-mediated immune responses is by directly targeting protein antigens to immune cells. Targeting of antigens to the dendritic cell (DC) molecule Clec9A has been shown to enhance antibody affinity and titers for model antigens, and influenza and enterovirus antigens, and may be advantageous for immunogens that otherwise fail to elicit antibodies with sufficient titers and breadth for broad protection, such as the envelope protein (Env) of HIV. Previously employed targeting strategies often utilize receptor-specific antibodies, however it is impractical to conjugate a bivalent IgG antibody to oligomeric antigens, including HIV Env trimers. Here we designed single chain variable fragment (scFv) and single chain Fab (scFab) constructs of a Clec9A-targeting antibody, expressed as genetically fused conjugates with the soluble ectodomain of Env, gp140. This conjugation did not affect the presentation of Env neutralising antibody epitopes. The scFab moiety was shown to be more stable than scFv, and in the context of gp140 fusions, was able to mediate better binding to recombinant and cell surface-expressed Clec9A, although the level of binding to cell-surface Clec9A was lower than that of the anti-Clec9A IgG. However, binding to Clec9A on the surface of DCs was not detected. Mouse immunization experiments suggested that the Clec9A-binding activity of the scFab-gp140 conjugate was insufficient to enhance Env-specific antibody responses. This is an important first proof of principle study demonstrating the conjugation of a scFab to an oligomeric protein antigen, and that an scFab displays better antigen binding than the corresponding scFv. Future developments of this technique that increase the scFab affinity will provide a valuable means to target oligomeric proteins to cell surface antigens of interest, improving vaccine-generated immune responses.
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MESH Headings
- AIDS Vaccines/administration & dosage
- AIDS Vaccines/genetics
- AIDS Vaccines/immunology
- Animals
- Antibodies, Neutralizing/immunology
- Antibody Affinity
- Antigens, Viral/genetics
- Antigens, Viral/immunology
- Dendritic Cells/immunology
- Dendritic Cells/metabolism
- Epitopes/immunology
- Female
- HEK293 Cells
- HIV Antibodies/immunology
- HIV Infections/immunology
- HIV Infections/therapy
- HIV Infections/virology
- Humans
- Immunogenicity, Vaccine
- Lectins, C-Type/immunology
- Lectins, C-Type/metabolism
- Mice
- Proof of Concept Study
- Protein Domains/genetics
- Protein Domains/immunology
- Receptors, Mitogen/immunology
- Receptors, Mitogen/metabolism
- Recombinant Fusion Proteins/administration & dosage
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/immunology
- Single-Chain Antibodies/administration & dosage
- Single-Chain Antibodies/genetics
- Single-Chain Antibodies/immunology
- Vaccination/methods
- Vaccines, DNA/administration & dosage
- Vaccines, DNA/genetics
- Vaccines, DNA/immunology
- env Gene Products, Human Immunodeficiency Virus/administration & dosage
- env Gene Products, Human Immunodeficiency Virus/genetics
- env Gene Products, Human Immunodeficiency Virus/immunology
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Affiliation(s)
- Hannah A. D. King
- Disease Elimination, Burnet Institute, Melbourne, Victoria, Australia
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Christopher A. Gonelli
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Kirsteen M. Tullett
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria, Australia
| | - Mireille H. Lahoud
- Disease Elimination, Burnet Institute, Melbourne, Victoria, Australia
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria, Australia
| | - Damian F. J. Purcell
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Heidi E. Drummer
- Disease Elimination, Burnet Institute, Melbourne, Victoria, Australia
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
- Department of Microbiology, Monash University, Melbourne, Victoria, Australia
| | - Pantelis Poumbourios
- Disease Elimination, Burnet Institute, Melbourne, Victoria, Australia
- Department of Microbiology, Monash University, Melbourne, Victoria, Australia
| | - Rob J. Center
- Disease Elimination, Burnet Institute, Melbourne, Victoria, Australia
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
- * E-mail:
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9
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Gonelli CA, Khoury G, Center RJ, Purcell DFJ. HIV-1-based Virus-like Particles that Morphologically Resemble Mature, Infectious HIV-1 Virions. Viruses 2019; 11:v11060507. [PMID: 31159488 PMCID: PMC6630479 DOI: 10.3390/v11060507] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 05/23/2019] [Accepted: 05/29/2019] [Indexed: 01/04/2023] Open
Abstract
A prophylactic vaccine eliciting both broad neutralizing antibodies (bNAbs) to the HIV-1 envelope glycoprotein (Env) and strong T cell responses would be optimal for preventing HIV-1 transmissions. Replication incompetent HIV-1 virus-like particles (VLPs) offer the opportunity to present authentic-structured, virion-associated Env to elicit bNAbs, and also stimulate T cell responses. Here, we optimize our DNA vaccine plasmids as VLP expression vectors for efficient Env incorporation and budding. The original vector that was used in human trials inefficiently produced VLPs, but maximized safety by inactivating RNA genome packaging, enzyme functions that are required for integration into the host genome, and deleting accessory proteins Vif, Vpr, and Nef. These original DNA vaccine vectors generated VLPs with incomplete protease-mediated cleavage of Gag and were irregularly sized. Mutations to restore function within the defective genes revealed that several of the reverse transcriptase (RT) deletions mediated this immature phenotype. Here, we made efficient budding, protease-processed, and mature-form VLPs that resembled infectious virions by introducing alternative mutations that completely removed the RT domain, but preserved most other safety mutations. These VLPs, either expressed from DNA vectors in vivo or purified after expression in vitro, are potentially useful immunogens that can be used to elicit antibody responses that target Env on fully infectious HIV-1 virions.
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Affiliation(s)
- Christopher A Gonelli
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria 3000, Australia.
| | - Georges Khoury
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria 3000, Australia.
| | - Rob J Center
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria 3000, Australia.
- Viral Entry and Vaccines Laboratory, Disease Elimination, Burnet Institute, Melbourne, Victoria 3004, Australia.
| | - Damian F J Purcell
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria 3000, Australia.
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10
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Parsons MS, Lloyd SB, Lee WS, Kristensen AB, Amarasena T, Center RJ, Keele BF, Lifson JD, LaBranche CC, Montefiori D, Wines BD, Hogarth PM, Swiderek KM, Venturi V, Davenport MP, Kent SJ. Partial efficacy of a broadly neutralizing antibody against cell-associated SHIV infection. Sci Transl Med 2018; 9:9/402/eaaf1483. [PMID: 28794282 DOI: 10.1126/scitranslmed.aaf1483] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 12/08/2016] [Accepted: 05/09/2017] [Indexed: 12/26/2022]
Abstract
Broadly neutralizing antibodies (BnAbs) protect macaques from cell-free simian/human immunodeficiency virus (SHIV) challenge, but their efficacy against cell-associated SHIV is unclear. Virus in cell-associated format is highly infectious, present in transmission-competent bodily fluids, and potentially capable of evading antibody-mediated neutralization. The PGT121 BnAb, which recognizes an epitope consisting of the V3 loop and envelope glycans, mediates antibody-dependent cellular cytotoxicity and neutralization of cell-to-cell HIV-1 transmission. To evaluate whether a BnAb can prevent infection after cell-associated viral challenge, we infused pigtail macaques with PGT121 or an isotype control and challenged animals 1 hour later intravenously with SHIVSF162P3-infected splenocytes. All five controls had high viremia 1 week after challenge. Three of six PGT121-infused animals were completely protected, two of six animals had a 1-week delay in onset of high viremia, and one animal had a 7-week delay in onset of viremia. The infused antibody had decayed on average to 2.0 μg/ml by 1 week after infusion and was well below 1 μg/ml (range, <0.1 to 0.8 μg/ml) by 8 weeks. The animals with a 1-week delay before high viremia had relatively lower plasma concentrations of PGT121. Transfer of 22 million peripheral blood mononuclear cells (PBMCs) stored at weeks 1 to 4 from the animal with the 7-week delayed onset of viremia into uninfected macaques did not initiate infection. Our results show that HIV-1-specific neutralizing antibodies have partial efficacy against cell-associated virus exposure in macaques. We conclude that sustaining high concentrations of bioavailable BnAb is important for protecting against cell-associated virus.
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Affiliation(s)
- Matthew S Parsons
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria 3000, Australia.
| | - Sarah B Lloyd
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria 3000, Australia
| | - Wen Shi Lee
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria 3000, Australia
| | - Anne B Kristensen
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria 3000, Australia
| | - Thakshila Amarasena
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria 3000, Australia
| | - Rob J Center
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria 3000, Australia.,Centre for Biomedical Research, Burnet Institute, Melbourne, Victoria 3004, Australia
| | - Brandon F Keele
- AIDS and Cancer Virus Program, Leidos Biomedical Research Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Jeffrey D Lifson
- AIDS and Cancer Virus Program, Leidos Biomedical Research Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | | | | | - Bruce D Wines
- Centre for Biomedical Research, Burnet Institute, Melbourne, Victoria 3004, Australia
| | - P Mark Hogarth
- Centre for Biomedical Research, Burnet Institute, Melbourne, Victoria 3004, Australia
| | | | - Vanessa Venturi
- Kirby Institute for Infection and Immunity, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Miles P Davenport
- Kirby Institute for Infection and Immunity, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Stephen J Kent
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria 3000, Australia. .,Melbourne Sexual Health Centre, Alfred Hospital Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, Victoria 3053, Australia.,Australian Research Council Centre of Excellence in Convergent Bio-Nano Science and Technology, University of Melbourne, Parkville, Victoria 3052, Australia
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11
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Center RJ. Memory B Cells, the HLA-B*57 Allele and Natural Control of HIV Infection. EBioMedicine 2017. [PMID: 28629910 PMCID: PMC5514400 DOI: 10.1016/j.ebiom.2017.06.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
- Rob J Center
- Burnet Institute, Disease Elimination Program, Life Sciences, Melbourne, Victoria, Australia.
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12
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Vietheer PT, Boo I, Gu J, McCaffrey K, Edwards S, Owczarek C, Hardy MP, Fabri L, Center RJ, Poumbourios P, Drummer HE. The core domain of hepatitis C virus glycoprotein E2 generates potent cross-neutralizing antibodies in guinea pigs. Hepatology 2017; 65:1117-1131. [PMID: 27997681 PMCID: PMC5408392 DOI: 10.1002/hep.28989] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 11/24/2016] [Accepted: 11/28/2016] [Indexed: 02/06/2023]
Abstract
UNLABELLED A vaccine that prevents hepatitis C virus (HCV) infection is urgently needed to support an emerging global elimination program. However, vaccine development has been confounded because of HCV's high degree of antigenic variability and the preferential induction of type-specific immune responses with limited potency against heterologous viral strains and genotypes. We showed previously that deletion of the three variable regions from the E2 receptor-binding domain (Δ123) increases the ability of human broadly neutralizing antibodies (bNAbs) to inhibit E2-CD81 receptor interactions, suggesting improved bNAb epitope exposure. In this study, the immunogenicity of Δ123 was examined. We show that high-molecular-weight forms of Δ123 elicit distinct antibody specificities with potent and broad neutralizing activity against all seven HCV genotypes. Antibody competition studies revealed that immune sera raised to high-molecular-weight Δ123 was poly specific, given that it inhibited the binding of human bNAbs directed to three major neutralization epitopes on E2. By contrast, the immune sera raised to monomeric Δ123 predominantly blocked the binding of a non-neutralizing antibody to Δ123, while having reduced ability to block bNAb binding to E2, and neutralization was largely toward the homologous genotype. This increased ability of oligomeric Δ123 to generate bNAbs correlates with occlusion of the non-neutralizing face of E2 in this glycoprotein form. CONCLUSION The results from this study reveal new information on the antigenic and immunogenic potential of E2-based immunogens and provide a pathway for the development of a simple, recombinant protein-based prophylactic vaccine for HCV with potential for universal protection. (Hepatology 2017;65:1117-1131).
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Affiliation(s)
- Patricia T. Vietheer
- Centre for Biomedical ResearchBurnet InstituteMelbourneAustralia
- Department of MicrobiologyMonash UniversityClaytonAustralia
| | - Irene Boo
- Centre for Biomedical ResearchBurnet InstituteMelbourneAustralia
| | - Jun Gu
- Centre for Biomedical ResearchBurnet InstituteMelbourneAustralia
- Department of MicrobiologyMonash UniversityClaytonAustralia
| | - Kathleen McCaffrey
- Centre for Biomedical ResearchBurnet InstituteMelbourneAustralia
- Department of Microbiology and Immunology at The Peter Doherty Institute for Infection and ImmunityUniversity of MelbourneParkvilleAustralia
| | | | | | | | | | - Rob J. Center
- Centre for Biomedical ResearchBurnet InstituteMelbourneAustralia
- Department of Microbiology and Immunology at The Peter Doherty Institute for Infection and ImmunityUniversity of MelbourneParkvilleAustralia
| | - Pantelis Poumbourios
- Centre for Biomedical ResearchBurnet InstituteMelbourneAustralia
- Department of MicrobiologyMonash UniversityClaytonAustralia
| | - Heidi E. Drummer
- Centre for Biomedical ResearchBurnet InstituteMelbourneAustralia
- Department of Microbiology and Immunology at The Peter Doherty Institute for Infection and ImmunityUniversity of MelbourneParkvilleAustralia
- Department of MicrobiologyMonash UniversityClaytonAustralia
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13
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Murray JM, Maher S, Mota T, Suzuki K, Kelleher AD, Center RJ, Purcell D. Differentiating founder and chronic HIV envelope sequences. PLoS One 2017; 12:e0171572. [PMID: 28187204 PMCID: PMC5302377 DOI: 10.1371/journal.pone.0171572] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 01/23/2017] [Indexed: 11/27/2022] Open
Abstract
Significant progress has been made in characterizing broadly neutralizing antibodies against the HIV envelope glycoprotein Env, but an effective vaccine has proven elusive. Vaccine development would be facilitated if common features of early founder virus required for transmission could be identified. Here we employ a combination of bioinformatic and operations research methods to determine the most prevalent features that distinguish 78 subtype B and 55 subtype C founder Env sequences from an equal number of chronic sequences. There were a number of equivalent optimal networks (based on the fewest covarying amino acid (AA) pairs or a measure of maximal covariance) that separated founders from chronics: 13 pairs for subtype B and 75 for subtype C. Every subtype B optimal solution contained the founder pairs 178–346 Asn-Val, 232–236 Thr-Ser, 240–340 Lys-Lys, 279–315 Asp-Lys, 291–792 Ala-Ile, 322–347 Asp-Thr, 535–620 Leu-Asp, 742–837 Arg-Phe, and 750–836 Asp-Ile; the most common optimal pairs for subtype C were 644–781 Lys-Ala (74 of 75 networks), 133–287 Ala-Gln (73/75) and 307–337 Ile-Gln (73/75). No pair was present in all optimal subtype C solutions highlighting the difficulty in targeting transmission with a single vaccine strain. Relative to the size of its domain (0.35% of Env), the α4β7 binding site occurred most frequently among optimal pairs, especially for subtype C: 4.2% of optimal pairs (1.2% for subtype B). Early sequences from 5 subtype B pre-seroconverters each exhibited at least one clone containing an optimal feature 553–624 (Ser-Asn), 724–747 (Arg-Arg), or 46–293 (Arg-Glu).
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Affiliation(s)
- John M. Murray
- School of Mathematics and Statistics, UNSW Sydney, Sydney, New South Wales, Australia
- * E-mail:
| | - Stephen Maher
- School of Mathematics and Statistics, UNSW Sydney, Sydney, New South Wales, Australia
- Zuse Institute Berlin, Berlin, Germany
| | - Talia Mota
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Kazuo Suzuki
- The Kirby Institute, UNSW Sydney, Sydney, New South Wales, Australia
| | | | - Rob J. Center
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Damian Purcell
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
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14
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Heydarchi B, Center RJ, Bebbington J, Cuthbertson J, Gonelli C, Khoury G, Mackenzie C, Lichtfuss M, Rawlin G, Muller B, Purcell D. Trimeric gp120-specific bovine monoclonal antibodies require cysteine and aromatic residues in CDRH3 for high affinity binding to HIV Env. MAbs 2016; 9:550-566. [PMID: 27996375 PMCID: PMC5384801 DOI: 10.1080/19420862.2016.1270491] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/29/2022] Open
Abstract
We isolated HIV-1 Envelope (Env)-specific memory B cells from a cow that had developed high titer polyclonal immunoglobulin G (IgG) with broad neutralizing activity after a long duration vaccination with HIV-1AD8 Env gp140 trimers. We cloned the bovine IgG matched heavy (H) and light (L) chain variable (V) genes from these memory B cells and constructed IgG monoclonal antibodies (mAbs) with either a human constant (C)-region/bovine V-region chimeric or fully bovine C and V regions. Among 42 selected Ig+ memory B cells, two mAbs (6A and 8C) showed high affinity binding to gp140 Env. Characterization of both the fully bovine and human chimeric isoforms of these two mAbs revealed them as highly type-specific and capable of binding only to soluble AD8 uncleaved gp140 trimers and covalently stabilized AD8 SOSIP gp140 cleaved trimers, but not monomeric gp120. Genomic sequence analysis of the V genes showed the third heavy complementarity-determining region (CDRH3) of 6A mAb was 21 amino acids in length while 8C CDRH3 was 14 amino acids long. The entire V heavy (VH) region was 27% and 25% diverged for 6A and 8C, respectively, from the best matched germline V genes available, and the CDRH3 regions of 6A and 8C were 47.62% and 78.57% somatically mutated, respectively, suggesting a high level of somatic hypermutation compared with CDRH3 of other species. Alanine mutagenesis of the VH genes of 6A and 8C, showed that CDRH3 cysteine and tryptophan amino acids were crucial for antigen binding. Therefore, these bovine vaccine-induced anti-HIV antibodies shared some of the notable structural features of elite human broadly neutralizing antibodies, such as CDRH3 size and somatic mutation during affinity-maturation. However, while the 6A and 8C mAbs inhibited soluble CD4 binding to gp140 Env, they did not recapitulate the neutralizing activity of the polyclonal antibodies against HIV infection.
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Affiliation(s)
- Behnaz Heydarchi
- a Department of Microbiology and Immunology , The University of Melbourne at The Peter Doherty Institute for Infection & Immunity , Melbourne , VIC , Australia
| | - Rob J Center
- a Department of Microbiology and Immunology , The University of Melbourne at The Peter Doherty Institute for Infection & Immunity , Melbourne , VIC , Australia
| | - Jonathan Bebbington
- a Department of Microbiology and Immunology , The University of Melbourne at The Peter Doherty Institute for Infection & Immunity , Melbourne , VIC , Australia
| | - Jack Cuthbertson
- a Department of Microbiology and Immunology , The University of Melbourne at The Peter Doherty Institute for Infection & Immunity , Melbourne , VIC , Australia
| | - Christopher Gonelli
- a Department of Microbiology and Immunology , The University of Melbourne at The Peter Doherty Institute for Infection & Immunity , Melbourne , VIC , Australia
| | - Georges Khoury
- a Department of Microbiology and Immunology , The University of Melbourne at The Peter Doherty Institute for Infection & Immunity , Melbourne , VIC , Australia
| | - Charlene Mackenzie
- a Department of Microbiology and Immunology , The University of Melbourne at The Peter Doherty Institute for Infection & Immunity , Melbourne , VIC , Australia
| | - Marit Lichtfuss
- a Department of Microbiology and Immunology , The University of Melbourne at The Peter Doherty Institute for Infection & Immunity , Melbourne , VIC , Australia
| | - Grant Rawlin
- a Department of Microbiology and Immunology , The University of Melbourne at The Peter Doherty Institute for Infection & Immunity , Melbourne , VIC , Australia
| | - Brian Muller
- a Department of Microbiology and Immunology , The University of Melbourne at The Peter Doherty Institute for Infection & Immunity , Melbourne , VIC , Australia
| | - Damian Purcell
- a Department of Microbiology and Immunology , The University of Melbourne at The Peter Doherty Institute for Infection & Immunity , Melbourne , VIC , Australia
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15
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Heydarchi B, Center RJ, Gonelli C, Muller B, Mackenzie C, Khoury G, Lichtfuss M, Rawlin G, Purcell DFJ. Repeated Vaccination of Cows with HIV Env gp140 during Subsequent Pregnancies Elicits and Sustains an Enduring Strong Env-Binding and Neutralising Antibody Response. PLoS One 2016; 11:e0157353. [PMID: 27300145 PMCID: PMC4907510 DOI: 10.1371/journal.pone.0157353] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 05/28/2016] [Indexed: 11/18/2022] Open
Abstract
An important feature of a potential vaccine against HIV is the production of broadly neutralising antibodies (BrNAbs) capable of potentially blocking infectivity of a diverse array of HIV strains. BrNAbs naturally arise in some HIV infected individuals after several years of infection and their serum IgG can neutralise various HIV strains across different subtypes. We previously showed that vaccination of cows with HIV gp140 AD8 trimers resulted in a high titre of serum IgG against HIV envelope (Env) that had strong BrNAb activity. These polyclonal BrNAbs concentrated into the colostrum during the late stage of pregnancy and can be harvested in vast quantities immediately after calving. In this study, we investigated the effect of prolonged HIV gp140 vaccination on bovine colostrum IgG HIV Env-binding and BrNAb activity over subsequent pregnancies. Repeated immunisation led to a maintained high titre of HIV Env specific IgG in the colostrum batches, but this did not increase through repeated cycles. Colostrum IgG from all batches also strongly competed with sCD4 binding to gp140 Env trimer and with human-derived monoclonal VRC01 and b12 BrNAbs that bind the CD4 binding site (CD4bs). Furthermore, competition neutralisation assays using RSC3 Env gp120 protein core and a derivative CD4bs mutant, RSC3 Δ371I/P363N, showed that CD4bs neutralising antibodies contribute to the neutralising activity of all batches of purified bovine colostrum IgG. This result indicates that the high IgG titre/avidity of anti-CD4bs antibodies with BrNAb activity was achieved during the first year of vaccination and was sustained throughout the years of repeated vaccinations in the cow tested. Although IgG of subsequent colostrum batches may have a higher avidity towards the CD4bs, the overall breadth in neutralisation was not enhanced. This implies that the boosting vaccinations over 4 years elicited a polyclonal antibody response that maintained the proportion of both neutralising and non-neutralising CD4bs antibodies.
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Affiliation(s)
- Behnaz Heydarchi
- Department of Microbiology and Immunology, at The Peter Doherty Institute for Infection & Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Rob J. Center
- Department of Microbiology and Immunology, at The Peter Doherty Institute for Infection & Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Christopher Gonelli
- Department of Microbiology and Immunology, at The Peter Doherty Institute for Infection & Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Brian Muller
- Department of Microbiology and Immunology, at The Peter Doherty Institute for Infection & Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Charlene Mackenzie
- Department of Microbiology and Immunology, at The Peter Doherty Institute for Infection & Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Georges Khoury
- Department of Microbiology and Immunology, at The Peter Doherty Institute for Infection & Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Marit Lichtfuss
- Department of Microbiology and Immunology, at The Peter Doherty Institute for Infection & Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Grant Rawlin
- Department of Microbiology and Immunology, at The Peter Doherty Institute for Infection & Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Damian F. J. Purcell
- Department of Microbiology and Immunology, at The Peter Doherty Institute for Infection & Immunity, The University of Melbourne, Melbourne, Victoria, Australia
- * E-mail:
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Gooneratne SL, Center RJ, Kent SJ, Parsons MS. Functional advantage of educated KIR2DL1(+) natural killer cells for anti-HIV-1 antibody-dependent activation. Clin Exp Immunol 2016; 184:101-9. [PMID: 26647083 DOI: 10.1111/cei.12752] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 11/13/2015] [Accepted: 11/25/2015] [Indexed: 11/28/2022] Open
Abstract
Evidence from the RV144 HIV-1 vaccine trial implicates anti-HIV-1 antibody-dependent cellular cytotoxicity (ADCC) in vaccine-conferred protection from infection. Among effector cells that mediate ADCC are natural killer (NK) cells. The ability of NK cells to be activated in an antibody-dependent manner is reliant upon several factors. In general, NK cell-mediated antibody-dependent activation is most robust in terminally differentiated CD57(+) NK cells, as well as NK cells educated through ontological interactions between inhibitory killer immunoglobulin-like receptors (KIR) and their major histocompatibility complex class I [MHC-I or human leucocyte antigen (HLA-I)] ligands. With regard to anti-HIV-1 antibody-dependent NK cell activation, previous research has demonstrated that the epidemiologically relevant KIR3DL1/HLA-Bw4 receptor/ligand combination confers enhanced activation potential. In the present study we assessed the ability of the KIR2DL1/HLA-C2 receptor/ligand combination to confer enhanced activation upon direct stimulation with HLA-I-devoid target cells or antibody-dependent stimulation with HIV-1 gp140-pulsed CEM.NKr-CCR5 target cells in the presence of an anti-HIV-1 antibody source. Among donors carrying the HLA-C2 ligand for KIR2DL1, higher interferon (IFN)-γ production was observed within KIR2DL1(+) NK cells than in KIR2DL1(-) NK cells upon both direct and antibody-dependent stimulation. No differences in KIR2DL1(+) and KIR2DL1(-) NK cell activation were observed in HLA-C1 homozygous donors. Additionally, higher activation in KIR2DL1(+) than KIR2DL1(-) NK cells from HLA-C2 carrying donors was observed within less differentiated CD57(-) NK cells, demonstrating that the observed differences were due to education and not an overabundance of KIR2DL1(+) NK cells within differentiated CD57(+) NK cells. These observations are relevant for understanding the regulation of anti-HIV-1 antibody-dependent NK cell responses.
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Affiliation(s)
- S L Gooneratne
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia
| | - R J Center
- Centre for Biomedical Research, Burnet Institute, Melbourne, VIC, Australia
| | - S J Kent
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia.,Melbourne Sexual Health Centre, Carlton, VIC, Australia.,ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, University of Melbourne, Melbourne, VIC, Australia
| | - M S Parsons
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia
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Madhavi V, Ana-Sosa-Batiz FE, Jegaskanda S, Center RJ, Winnall WR, Parsons MS, Ananworanich J, Cooper DA, Kelleher AD, Hsu D, Pett S, Stratov I, Kramski M, Kent SJ. Antibody-dependent effector functions against HIV decline in subjects receiving antiretroviral therapy. J Infect Dis 2014; 211:529-38. [PMID: 25170105 DOI: 10.1093/infdis/jiu486] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Combination antiretroviral therapy (cART) effectively controls human immunodeficiency virus (HIV) infection but does not eliminate HIV, and lifelong treatment is therefore required. HIV-specific cytotoxic T lymphocyte (CTL) responses decline following cART initiation. Alterations in other HIV-specific immune responses that may assist in eliminating latent HIV infection, specifically antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent phagocytosis (ADP), are unclear. METHODS A cohort of 49 cART-naive HIV-infected subjects from Thailand (mean baseline CD4 count, 188 cells/µL; mean viral load, 5.4 log10 copies/mL) was followed for 96 weeks after initiating cART. ADCC and ADP assays were performed using serum samples obtained at baseline and after 96 weeks of cART. RESULTS A 35% reduction in HIV type 1 envelope (Env)-specific ADCC-mediated killing of target cells (P<.001) was observed after 96 weeks of cART. This was corroborated by a significant reduction in the ability of Env-specific ADCC antibodies to activate natural killer cells (P<.001). Significantly reduced ADP was also observed after 96 weeks of cART (P=.018). CONCLUSIONS This longitudinal study showed that cART resulted in significant reductions of HIV-specific effector antibody responses, including ADCC and ADP. Therapeutic vaccines or other immunomodulatory approaches may be required to improve antibody-mediated control of HIV during cART.
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Affiliation(s)
- Vijaya Madhavi
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville
| | - Fernanda E Ana-Sosa-Batiz
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville
| | - Sinthujan Jegaskanda
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville
| | - Rob J Center
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville
| | - Wendy R Winnall
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville
| | - Matthew S Parsons
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville
| | - Jintanat Ananworanich
- Thai Red Cross AIDS Research Centre, HIV Netherlands Australia Thailand Research Collaboration, Bangkok, Thailand
| | - David A Cooper
- Kirby Institute for Infection and Immunity in Society, University of New South Wales, Sydney, Australia
| | - Anthony D Kelleher
- Kirby Institute for Infection and Immunity in Society, University of New South Wales, Sydney, Australia
| | - Denise Hsu
- Kirby Institute for Infection and Immunity in Society, University of New South Wales, Sydney, Australia
| | - Sarah Pett
- Kirby Institute for Infection and Immunity in Society, University of New South Wales, Sydney, Australia Medical Research Council Clinical Trials Unit, Department of Infection and Population Health, University College London, United Kingdom
| | - Ivan Stratov
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville
| | - Marit Kramski
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville
| | - Stephen J Kent
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville
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Nasr N, Lai J, Botting RA, Mercier SK, Harman AN, Kim M, Turville S, Center RJ, Domagala T, Gorry PR, Olbourne N, Cunningham AL. Inhibition of two temporal phases of HIV-1 transfer from primary Langerhans cells to T cells: the role of langerin. J Immunol 2014; 193:2554-64. [PMID: 25070850 DOI: 10.4049/jimmunol.1400630] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Epidermal Langerhans cells (eLCs) uniquely express the C-type lectin receptor langerin in addition to the HIV entry receptors CD4 and CCR5. They are among the first target cells to encounter HIV in the anogenital stratified squamous mucosa during sexual transmission. Previous reports on the mechanism of HIV transfer to T cells and the role of langerin have been contradictory. In this study, we examined HIV replication and langerin-mediated viral transfer by authentic immature eLCs and model Mutz-3 LCs. eLCs were productively infected with HIV, whereas Mutz-3 LCs were not susceptible because of a lack of CCR5 expression. Two successive phases of HIV viral transfer to T cells via cave/vesicular trafficking and de novo replication were observed with eLCs as previously described in monocyte-derived or blood dendritic cells, but only first phase transfer was observed with Mutz-3 LCs. Langerin was expressed as trimers after cross-linking on the cell surface of Mutz-3 LCs and in this form preferentially bound HIV envelope protein gp140 and whole HIV particles via the carbohydrate recognition domain (CRD). Both phases of HIV transfer from eLCs to T cells were inhibited when eLCs were pretreated with a mAb to langerin CRD or when HIV was pretreated with a soluble langerin trimeric extracellular domain or by a CRD homolog. However, the langerin homolog did not inhibit direct HIV infection of T cells. These two novel soluble langerin inhibitors could be developed to prevent HIV uptake, infection, and subsequent transfer to T cells during early stages of infection.
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Affiliation(s)
- Najla Nasr
- Centre for Virus Research, Westmead Millennium Institute, Westmead, New South Wales 2145, Australia; University of Sydney, Sydney, New South Wales 2000, Australia
| | - Joey Lai
- Centre for Virus Research, Westmead Millennium Institute, Westmead, New South Wales 2145, Australia; University of Sydney, Sydney, New South Wales 2000, Australia
| | - Rachel A Botting
- Centre for Virus Research, Westmead Millennium Institute, Westmead, New South Wales 2145, Australia; University of Sydney, Sydney, New South Wales 2000, Australia
| | - Sarah K Mercier
- Centre for Virus Research, Westmead Millennium Institute, Westmead, New South Wales 2145, Australia; University of Sydney, Sydney, New South Wales 2000, Australia
| | - Andrew N Harman
- Centre for Virus Research, Westmead Millennium Institute, Westmead, New South Wales 2145, Australia; University of Sydney, Sydney, New South Wales 2000, Australia
| | - Min Kim
- Centre for Virus Research, Westmead Millennium Institute, Westmead, New South Wales 2145, Australia; University of Sydney, Sydney, New South Wales 2000, Australia
| | - Stuart Turville
- Centre for Virus Research, Westmead Millennium Institute, Westmead, New South Wales 2145, Australia; University of Sydney, Sydney, New South Wales 2000, Australia
| | - Rob J Center
- Department of Microbiology and Immunology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Teresa Domagala
- Apollo Life Sciences Pty, Beaconsfield, New South Wales 2015, Australia
| | - Paul R Gorry
- Centre for Biomedical Research, Burnet Institute, Melbourne, Victoria 3004, Australia; and
| | - Norman Olbourne
- Sydney Institute of Plastic and Reconstructive Surgery, Chatswood, New South Wales 2067, Australia
| | - Anthony L Cunningham
- Centre for Virus Research, Westmead Millennium Institute, Westmead, New South Wales 2145, Australia; University of Sydney, Sydney, New South Wales 2000, Australia;
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Center RJ, Miller A, Wheatley AK, Campbell SM, Siebentritt C, Purcell DFJ. Utility of the Sindbis replicon system as an Env-targeted HIV vaccine. Vaccine 2013; 31:2260-6. [PMID: 23499600 DOI: 10.1016/j.vaccine.2013.02.064] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 02/20/2013] [Accepted: 02/28/2013] [Indexed: 02/06/2023]
Abstract
Sindbis replicon-based vaccine vectors are designed to combine the immunostimulatory properties of replicating viruses with the superior safety profile of non-replicating systems. In this study we performed a detailed assessment of Sindbis (SIN) replicon vectors expressing HIV-1 envelope protein (Env) for the induction of cell-mediated and humoral immune responses in a small animal model. SIN-derived virus-like particles (VLP) elicited Env-specific antibody responses that were detectable after boosting with recombinant Env protein. This priming effect could be mediated by replicon activity alone but may be enhanced by Env attached to the surface of VLP, offering a potential advantage for this mode of replicon delivery for Env based vaccination strategies. In contrast, the Env-specific CTL responses that were elicited by SIN-VLP were entirely dependent on replicon activity. SIN-VLP priming induced more durable humoral responses than immunization with protein only. This is important from a vaccine perspective, given the intrinsic tendency of Env to induce short-lived antibody responses in the context of vaccination or infection. These results indicate that further efforts to enhance the magnitude and durability of the HIV-1 Env-specific immune responses generated by Sindbis vectors, either alone or as part of prime-boost regimens, are justified.
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Affiliation(s)
- Rob J Center
- Department of Microbiology and Immunology, University of Melbourne, Australia
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20
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French MA, Center RJ, Wilson KM, Fleyfel I, Fernandez S, Schorcht A, Stratov I, Kramski M, Kent SJ, Kelleher AD. Isotype-switched immunoglobulin G antibodies to HIV Gag proteins may provide alternative or additional immune responses to 'protective' human leukocyte antigen-B alleles in HIV controllers. AIDS 2013; 27:519-28. [PMID: 23364441 DOI: 10.1097/qad.0b013e32835cb720] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Natural control of HIV infection is associated with CD8 T-cell responses to Gag-encoded antigens of the HIV core and carriage of 'protective' human leukocyte antigen (HLA)-B alleles, but some HIV controllers do not possess these attributes. As slower HIV disease progression is associated with high levels of antibodies to HIV Gag proteins, we have examined antibodies to HIV proteins in controllers with and without 'protective' HLA-B alleles. METHODS Plasma from 32 HIV controllers and 21 noncontrollers was examined for immunoglobulin G1 (IgG1) and IgG2 antibodies to HIV proteins in virus lysates by western blot assay and to recombinant (r) p55 and gp140 by ELISA. Natural killer (NK) cell-activating antibodies and FcγRIIa-binding immune complexes were also assessed. RESULTS Plasma levels of IgG1 antibodies to HIV Gag (p18, p24, rp55) and Pol-encoded (p32, p51, p66) proteins were higher in HIV controllers. In contrast, IgG1 antibodies to Env proteins were less discriminatory, with only antigp120 levels being higher in controllers. High-level IgG2 antibodies to any Gag protein were most common in HIV controllers not carrying a 'protective' HLA-B allele, particularly HLA-B*57 (P = 0.016). HIV controllers without 'protective' HLA-B alleles also had higher plasma levels of IgG1 antip32 (P = 0.04). NK cell-activating antibodies to gp140 Env protein were higher in elite controllers but did not differentiate HIV controllers with or without 'protective' HLA-B alleles. IgG1 was increased in FcγRIIa-binding immune complexes from noncontrollers. CONCLUSION We hypothesize that isotype-switched (IgG2+) antibodies to HIV Gag proteins and possibly IgG1 antip32 may provide alternative or additional immune control mechanisms to HLA-restricted CD8 T-cell responses in HIV controllers.
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21
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Kramski M, Lichtfuss GF, Navis M, Isitman G, Wren L, Rawlin G, Center RJ, Jaworowski A, Kent SJ, Purcell DFJ. Anti-HIV-1 antibody-dependent cellular cytotoxicity mediated by hyperimmune bovine colostrum IgG. Eur J Immunol 2012; 42:2771-81. [PMID: 22730083 DOI: 10.1002/eji.201242469] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 05/11/2012] [Accepted: 06/15/2012] [Indexed: 11/07/2022]
Abstract
Antibodies with antibody-dependent cellular cytotoxicity (ADCC) activity play an important role in protection against HIV-1 infection, but generating sufficient amounts of antibodies to study their protective efficacy is difficult. HIV-specific IgG can be easily and inexpensively produced in large quantities using bovine colostrum. We previously vaccinated cows with HIV-1 envelope gp140 and elicited high titers of anti-gp140-binding IgG in colostrum. In the present study, we determined whether bovine antibodies would also demonstrate specific cytotoxic activity. We found that bovine IgG bind to Fcγ-receptors (FcγRs) on human neutrophils, monocytes, and NK cells in a dose-dependent manner. Antibody-dependent killing was observed in the presence of anti-HIV-1 colostrum IgG but not nonimmune colostrum IgG. Killing was dependent on Fc and FcγR interaction since ADDC activity was not seen with F(ab')(2) fragments. ADCC activity was primarily mediated by CD14(+) monocytes with FcγRIIa (CD32a) as the major receptor responsible for monocyte-mediated ADCC in response to bovine IgG. In conclusion, we demonstrate that bovine anti-HIV colostrum IgG have robust HIV-1-specific ADCC activity and therefore offer a useful source of antibodies able to provide a rapid and potent response against HIV-1 infection. This could assist the development of novel Ab-mediated approaches for prevention of HIV-1 transmission.
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Affiliation(s)
- Marit Kramski
- Department of Microbiology and Immunology, University of Melbourne, Melbourne, Australia.
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22
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Kramski M, Center RJ, Wheatley AK, Jacobson JC, Alexander MR, Rawlin G, Purcell DFJ. Hyperimmune bovine colostrum as a low-cost, large-scale source of antibodies with broad neutralizing activity for HIV-1 envelope with potential use in microbicides. Antimicrob Agents Chemother 2012; 56:4310-9. [PMID: 22664963 PMCID: PMC3421555 DOI: 10.1128/aac.00453-12] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 05/23/2012] [Indexed: 11/20/2022] Open
Abstract
Bovine colostrum (first milk) contains very high concentrations of IgG, and on average 1 kg (500 g/liter) of IgG can be harvested from each immunized cow immediately after calving. We used a modified vaccination strategy together with established production systems from the dairy food industry for the large-scale manufacture of broadly neutralizing HIV-1 IgG. This approach provides a low-cost mucosal HIV preventive agent potentially suitable for a topical microbicide. Four cows were vaccinated pre- and/or postconception with recombinant HIV-1 gp140 envelope (Env) oligomers of clade B or A, B, and C. Colostrum and purified colostrum IgG were assessed for cross-clade binding and neutralization against a panel of 27 Env-pseudotyped reporter viruses. Vaccination elicited high anti-gp140 IgG titers in serum and colostrum with reciprocal endpoint titers of up to 1 × 10(5). While nonimmune colostrum showed some intrinsic neutralizing activity, colostrum from 2 cows receiving a longer-duration vaccination regimen demonstrated broad HIV-1-neutralizing activity. Colostrum-purified polyclonal IgG retained gp140 reactivity and neutralization activity and blocked the binding of the b12 monoclonal antibody to gp140, showing specificity for the CD4 binding site. Colostrum-derived anti-HIV antibodies offer a cost-effective option for preparing the substantial quantities of broadly neutralizing antibodies that would be needed in a low-cost topical combination HIV-1 microbicide.
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Affiliation(s)
- Marit Kramski
- Department of Microbiology and Immunology, University of Melbourne, Parkville, Victoria, Australia
| | - Rob J. Center
- Department of Microbiology and Immunology, University of Melbourne, Parkville, Victoria, Australia
| | - Adam K. Wheatley
- Department of Microbiology and Immunology, University of Melbourne, Parkville, Victoria, Australia
| | - Jonathan C. Jacobson
- Department of Microbiology and Immunology, University of Melbourne, Parkville, Victoria, Australia
| | - Marina R. Alexander
- Department of Microbiology and Immunology, University of Melbourne, Parkville, Victoria, Australia
| | - Grant Rawlin
- Immuron Ltd., North Melbourne, Victoria, Australia
| | - Damian F. J. Purcell
- Department of Microbiology and Immunology, University of Melbourne, Parkville, Victoria, Australia
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23
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Kramski M, Schorcht A, Johnston APR, Lichtfuss GF, Jegaskanda S, De Rose R, Stratov I, Kelleher AD, French MA, Center RJ, Jaworowski A, Kent SJ. Role of monocytes in mediating HIV-specific antibody-dependent cellular cytotoxicity. J Immunol Methods 2012; 384:51-61. [PMID: 22841577 DOI: 10.1016/j.jim.2012.07.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2012] [Revised: 07/17/2012] [Accepted: 07/17/2012] [Indexed: 10/28/2022]
Abstract
Antibodies (Abs) that mediate antibody-dependent cellular cytotoxicity (ADCC) activity against HIV-1 are of major interest. A widely used method to measure ADCC Abs is the rapid and fluorometric antibody-dependent cellular cytotoxicity (RFADCC) assay. Antibody-dependent killing of a labelled target cell line by PBMC is assessed by loss of intracellular CFSE but retention of membrane dye PKH26 (CFSE-PKH26+). Cells of this phenotype are assumed to be derived from CFSE+PKH26+ target cells killed by NK cells. We assessed the effector cells that mediate ADCC in this assay. Backgating analysis and phenotyping of CFSE-PKH26+ revealed that the RFADCC assay's readout mainly represents CD3-CD14+ monocytes taking up the PKH26 dye. This was confirmed for 53 HIV+plasma-purified IgG samples when co-cultured with PBMC from three separate healthy donors. Emergence of the CFSE-PKH26+ monocyte population was observed upon co-culture of targets with purified monocytes but not with purified NK cells. Image flow cytometry and microscopy showed a monocyte-specific interaction with target cells without typical morphological changes associated with phagocytosis, suggesting a monocyte-mediated ADCC process. We conclude that the RFADCC assay primarily reflects Ab-mediated monocyte function. Further studies on the immunological importance of HIV-specific monocyte-mediated ADCC are warranted.
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Affiliation(s)
- M Kramski
- Department of Microbiology and Immunology, University of Melbourne, Australia.
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24
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Mota TM, Murray JM, Center RJ, Purcell DFJ, McCaw JM. Application of a case-control study design to investigate genotypic signatures of HIV-1 transmission. Retrovirology 2012; 9:54. [PMID: 22731404 PMCID: PMC3419081 DOI: 10.1186/1742-4690-9-54] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 06/25/2012] [Indexed: 12/03/2022] Open
Abstract
Background The characterization of HIV-1 transmission strains may inform the design of an effective vaccine. Shorter variable loops with fewer predicted glycosites have been suggested as signatures enriched in envelope sequences derived during acute HIV-1 infection. Specifically, a transmission-linked lack of glycosites within the V1 and V2 loops of gp120 provides greater access to an α4β7 binding motif, which promotes the establishment of infection. Also, a histidine at position 12 in the leader sequence of Env has been described as a transmission signature that is selected against during chronic infection. The purpose of this study is to measure the association of the presence of an α4β7 binding motif, the number of N-linked glycosites, the length of the variable loops, and the prevalence of histidine at position 12 with HIV-1 transmission. A case–control study design was used to measure the prevalence of these variables between subtype B and C transmission sequences and frequency-matched randomly-selected sequences derived from chronically infected controls. Results Subtype B transmission strains had shorter V3 regions than chronic strains (p = 0.031); subtype C transmission strains had shorter V1 loops than chronic strains (p = 0.047); subtype B transmission strains had more V3 loop glycosites (p = 0.024) than chronic strains. Further investigation showed that these statistically significant results were unlikely to be biologically meaningful. Also, there was no difference observed in the prevalence of a histidine at position 12 among transmission strains and controls of either subtype. Conclusions Although a genetic bottleneck is observed after HIV-1 transmission, our results indicate that summary characteristics of Env hypothesised to be important in transmission are not divergent between transmission and chronic strains of either subtype. The success of a transmission strain to initiate infection may be a random event from the divergent pool of donor viral sequences. The characteristics explored through this study are important, but may not function as genotypic signatures of transmission as previously described.
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Affiliation(s)
- Talia M Mota
- Department of Microbiology and Immunology, University of Melbourne, Parkville, VIC 3010, Australia
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Johansson SE, Rollman E, Chung AW, Center RJ, Hejdeman B, Stratov I, Hinkula J, Wahren B, Kärre K, Kent SJ, Berg L. NK cell function and antibodies mediating ADCC in HIV-1-infected viremic and controller patients. Viral Immunol 2011; 24:359-68. [PMID: 21958370 DOI: 10.1089/vim.2011.0025] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Natural killer (NK) cells have been suggested to play a protective role in HIV disease progression. One potent effector mechanism of NK cells is antibody-dependent cellular cytotoxicity (ADCC) mediated by antiviral antibodies binding to the FcγRIIIa receptor (CD16) on NK cells. We investigated NK cell-mediated ADCC function and the presence of ADCC antibodies in plasma from 20 HIV-1-infected patients and 10 healthy donors. The HIV-positive patients were divided into two groups: six who controlled viremia for at least 8 y without treatment (controllers), and 14 who were persistently viremic and not currently on treatment. Plasma from both patient groups induced NK cell IFN-γ expression and degranulation in response to HIV-1 envelope (Env) gp140-protein-coated cells. Patient antibodies mediating ADCC were largely directed towards the Env V3 loop, as identified by a gp140 protein lacking the V3 loop. Interestingly, in two controllers ADCC-mediating antibodies were more broadly directed to other parts of Env. A high viral load in patients correlated with decreased ADCC-mediated cytolysis of gp140-protein-coated target cells. NK cells from both infected patients and healthy donors degranulated efficiently in the presence of antibody-coated HIV-1-infected Jurkat cells. In conclusion, the character of ADCC-mediating antibodies differed in some controllers compared to viremic patients. NK cell ADCC activity is not compromised in HIV-infected patients.
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Affiliation(s)
- Susanne E Johansson
- Department of Microbiology, Tumor and Cell Biology and Strategic Research Center IRIS, Karolinska Institutet, Stockholm, Sweden
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Wheatley AK, Kramski M, Alexander MR, Toe JG, Center RJ, Purcell DFJ. Co-expression of miRNA targeting the expression of PERK, but not PKR, enhances cellular immunity from an HIV-1 Env DNA vaccine. PLoS One 2011; 6:e18225. [PMID: 21464971 PMCID: PMC3064671 DOI: 10.1371/journal.pone.0018225] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Accepted: 02/28/2011] [Indexed: 01/03/2023] Open
Abstract
Small non-coding micro-RNAs (miRNA) are important post-transcriptional regulators of mammalian gene expression that can be used to direct the knockdown of expression from targeted genes. We examined whether DNA vaccine vectors co-expressing miRNA with HIV-1 envelope (Env) antigens could influence the magnitude or quality of the immune responses to Env in mice. Human miR-155 and flanking regions from the non-protein encoding gene mirhg155 were introduced into an artificial intron within an expression vector for HIV-1 Env gp140. Using the miR-155-expressing intron as a scaffold, we developed novel vectors for miRNA-mediated targeting of the cellular antiviral proteins PKR and PERK, which significantly down-modulated target gene expression and led to increased Env expression in vitro. Finally, vaccinating BALB/c mice with a DNA vaccine vector delivering miRNA targeting PERK, but not PKR, was able to augment the generation of Env-specific T-cell immunity. This study provides proof-of-concept evidence that miRNA effectors incorporated into vaccine constructs can positively influence vaccine immunogenicity. Further testing of vaccine-encoded miRNA will determine if such strategies can enhance protective efficacy from vaccines against HIV-1 for eventual human use.
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Affiliation(s)
- Adam K. Wheatley
- Department of Microbiology and Immunology, University of Melbourne, Melbourne, Victoria, Australia
| | - Marit Kramski
- Department of Microbiology and Immunology, University of Melbourne, Melbourne, Victoria, Australia
| | - Marina R. Alexander
- Department of Microbiology and Immunology, University of Melbourne, Melbourne, Victoria, Australia
| | - Jesse G. Toe
- Department of Microbiology and Immunology, University of Melbourne, Melbourne, Victoria, Australia
- Division of Infection and Immunity, The Walter & Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia
| | - Rob J. Center
- Department of Microbiology and Immunology, University of Melbourne, Melbourne, Victoria, Australia
| | - Damian F. J. Purcell
- Department of Microbiology and Immunology, University of Melbourne, Melbourne, Victoria, Australia
- * E-mail:
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27
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Azimi I, Matthias LJ, Center RJ, Wong JWH, Hogg PJ. Disulfide bond that constrains the HIV-1 gp120 V3 domain is cleaved by thioredoxin. J Biol Chem 2010; 285:40072-80. [PMID: 20943653 PMCID: PMC3000989 DOI: 10.1074/jbc.m110.185371] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 10/10/2010] [Indexed: 11/06/2022] Open
Abstract
A functional disulfide bond in both the HIV envelope glycoprotein, gp120, and its immune cell receptor, CD4, is involved in viral entry, and compounds that block cleavage of the disulfide bond in these proteins inhibit HIV entry and infection. The disulfide bonds in both proteins are cleaved at the cell surface by the small redox protein, thioredoxin. The target gp120 disulfide and its mechanism of cleavage were determined using a thioredoxin kinetic trapping mutant and mass spectrometry. A single disulfide bond was cleaved in isolated and cell surface gp120, but not the gp160 precursor, and the extent of the reaction was enhanced when gp120 was bound to CD4. The Cys(32) sulfur ion of thioredoxin attacks the Cys(296) sulfur ion of the gp120 V3 domain Cys(296)-Cys(331) disulfide bond, cleaving the bond. Considering that V3 sequences largely determine the chemokine receptor preference of HIV, we propose that cleavage of the V3 domain disulfide, which is facilitated by CD4 binding, regulates chemokine receptor binding. There are 20 possible disulfide bond configurations, and, notably, the V3 domain disulfide has the same unusual -RHStaple configuration as the functional disulfide bond cleaved in CD4.
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Affiliation(s)
- Iman Azimi
- From the Lowy Cancer Research Centre and Prince of Wales Clinical School, University of New South Wales, Sydney, New South Wales 2052, Australia and
| | - Lisa J. Matthias
- From the Lowy Cancer Research Centre and Prince of Wales Clinical School, University of New South Wales, Sydney, New South Wales 2052, Australia and
| | - Rob J. Center
- the Department of Microbiology and Immunology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Jason W. H. Wong
- From the Lowy Cancer Research Centre and Prince of Wales Clinical School, University of New South Wales, Sydney, New South Wales 2052, Australia and
| | - Philip J. Hogg
- From the Lowy Cancer Research Centre and Prince of Wales Clinical School, University of New South Wales, Sydney, New South Wales 2052, Australia and
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28
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Alexander MR, Wheatley AK, Center RJ, Purcell DFJ. Efficient transcription through an intron requires the binding of an Sm-type U1 snRNP with intact stem loop II to the splice donor. Nucleic Acids Res 2010; 38:3041-53. [PMID: 20071748 PMCID: PMC2875018 DOI: 10.1093/nar/gkp1224] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The mechanism behind the positive action of introns upon transcription and the biological significance of this positive feedback remains unclear. Functional ablation of splice sites within an HIV-derived env cDNA significantly reduced transcription that was rescued by a U1 snRNA modified to bind to the mutated splice donor (SD). Using this model we further characterized both the U1 and pre-mRNA structural requirements for transcriptional enhancement. U1 snRNA rescued as a mature Sm-type snRNP with an intact stem loop II. Position and sequence context for U1-binding is crucial because a promoter proximal intron placed upstream of the mutated SD failed to rescue transcription. Furthermore, U1-rescue was independent of promoter and exon sequence and is partially replaced by the transcription elongation activator Tat, pointing to an intron-localized block in transcriptional elongation. Thus, transcriptional coupling of U1 snRNA binding to the SD may licence the polymerase for transcription through the intron.
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Affiliation(s)
- Marina R Alexander
- Department of Microbiology and Immunology, University of Melbourne, Melbourne 3010, Australia
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29
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Reddy SMR, Center RJ, Suzuki K, Gorry P, Kelleher A, Purcell DF. P12-01. Construction and characterization of recombinant envelope glycoproteins derived from HIV-1 pre-seroconversion strains as potential vaccine immunogens. Retrovirology 2009. [PMCID: PMC2767656 DOI: 10.1186/1742-4690-6-s3-p167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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30
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Peut V, Campbell S, Gaeguta A, Center RJ, Alcantara S, Fernandez C, Purcell DF, Kent SJ. P09-07. Balancing reversion of CTL and neutralizing antibody escape mutations within HIV-1 Env upon transmission. Retrovirology 2009. [PMCID: PMC2767605 DOI: 10.1186/1742-4690-6-s3-p120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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31
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Wheatley AK, Alexander MR, Toe JG, Center RJ, Purcell DF. OA021-03. Design and development of DNA vaccines for the co-expression of micro-RNA and HIV-1 Env. Retrovirology 2009. [PMCID: PMC2767535 DOI: 10.1186/1742-4690-6-s3-o15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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32
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Chung AW, Rollman E, Center RJ, Kent SJ, Stratov I. Rapid degranulation of NK cells following activation by HIV-specific antibodies. J Immunol 2009; 182:1202-10. [PMID: 19124764 DOI: 10.4049/jimmunol.182.2.1202] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Ab-dependent cellular cytotoxicity (ADCC) Abs stimulate NK cell effector functions and play a role in protecting from and controlling viral infections. We characterized ADCC Abs in a cross-sectional cohort of 80 HIV-infected subjects not on antiretroviral therapy. We analyzed ADCC response by killing fluorescently labeled target cells, as well as expression of IFN-gamma and the degranulation marker CD107a from activated NK cells as measured by a novel intracellular cytokine assay. HIV-specific ADCC directed toward Envelope proteins were present in the majority of 80 untreated HIV-infected individuals measured by killing function. Similarly, most subjects had HIV-specific Abs that mediated degranulation or cytokine expression by NK cells. Interestingly, there was a poor correlation between ADCC-mediated killing of fluorescently labeled whole Envelope protein-pulsed cell lines and Ab-mediated expression of IFN-gamma by NK cells. However, in contrast to healthy donor NK cells, autologous patient NK cells more effectively degranulated granzyme B in response to ADCC activation. Activation of NK cells in response to stimulation by HIV-specific Abs occurs at least as rapidly as activation of Gag-specific CTLs. Our studies highlight the complexity of ab-mediated NK cell activation in HIV infection, and suggest new avenues toward studying the utility of ADCC in controlling HIV infection.
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Affiliation(s)
- Amy W Chung
- Department of Microbiology and Immunology, University of Melbourne, Melbourne, Australia
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33
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Center RJ, Lebowitz J, Leapman RD, Moss B. Promoting trimerization of soluble human immunodeficiency virus type 1 (HIV-1) Env through the use of HIV-1/simian immunodeficiency virus chimeras. J Virol 2004; 78:2265-76. [PMID: 14963123 PMCID: PMC369220 DOI: 10.1128/jvi.78.5.2265-2276.2004] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The envelope proteins (Env) of human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV) form homo-oligomers in the endoplasmic reticulum. The oligomeric structure of Env is maintained, but is less stable, after cleavage in a Golgi compartment and transport to the surface of infected cells. Functional, virion-associated HIV-1 and SIV Env have an almost exclusively trimeric structure. In addition, a soluble form of SIV Env (gp140) forms a nearly homogeneous population of trimers. Here, we describe the oligomeric structure of soluble, uncleaved HIV-1 gp140 and modifications that promote a stable trimeric structure. Biochemical and biophysical analyses, including sedimentation equilibrium and scanning transmission electron microscopy, revealed that unmodified HIV-1 gp140 purified as a heterogeneous range of oligomeric species, including dimers and aggregates. Deletion of the V2 domain alone or, especially, both the V1 and V2 domains reduced dimer formation but promoted aggregation rather than trimerization. Expressing gp140 with mannose-only oligosaccharides did not eliminate heterogeneity. Replacement of the entire gp41 segment of HIV-1 gp140 or just the N-terminal half (85 amino acids) of this segment with the corresponding region of SIV was sufficient to confer efficient trimerization for gp140 derived from clade B and C isolates. Importantly, the relatively small segment of the HIV Env replaced by SIV sequences contains no known targets of neutralizing antibody. The soluble trimeric form of HIV-1 Env should prove useful for assessment of antigenic structure and immunogenicity.
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MESH Headings
- Chromatography, Gel
- Dimerization
- Gene Products, env/chemistry
- Gene Products, env/genetics
- Gene Products, env/metabolism
- Gene Products, env/ultrastructure
- HIV Envelope Protein gp41/chemistry
- HIV Envelope Protein gp41/genetics
- HIV Envelope Protein gp41/metabolism
- HIV-1/chemistry
- Mannose/analysis
- Microscopy, Electron, Scanning Transmission
- Molecular Weight
- Protein Structure, Quaternary
- Protein Structure, Tertiary
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Sequence Deletion
- Simian Immunodeficiency Virus/chemistry
- Solubility
- env Gene Products, Human Immunodeficiency Virus
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Affiliation(s)
- Rob J Center
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
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34
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Center RJ, Leapman RD, Lebowitz J, Arthur LO, Earl PL, Moss B. Oligomeric structure of the human immunodeficiency virus type 1 envelope protein on the virion surface. J Virol 2002; 76:7863-7. [PMID: 12097599 PMCID: PMC136379 DOI: 10.1128/jvi.76.15.7863-7867.2002] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The envelope protein (Env) of human immunodeficiency virus type 1 forms homo-oligomers in the endoplasmic reticulum. The oligomeric structure of Env is maintained after cleavage in a Golgi compartment and transport to the surfaces of infected cells, where incorporation into budding virions takes place. Here, we use biophysical techniques to assess the oligomeric valency of virion-associated Env prior to fusion activation. Virion-associated Env oligomers were stabilized by chemical cross-linking prior to detergent extraction and were purified by immunoaffinity chromatography. Gel filtration revealed a single predominant oligomeric species, and sedimentation equilibrium analysis-derived mass values indicated a trimeric structure. Determination of the masses of individual Env molecules by scanning transmission electron microscopy demonstrated that virion-associated Env was trimeric, and a triangular morphology was observed in 20 to 30% of the molecules. These results, which firmly establish the oligomeric structure of human immunodeficiency virus virion-associated Env, parallel those of our previous analysis of the simian immunodeficiency virus Env.
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Affiliation(s)
- Rob J Center
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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35
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Center RJ, Schuck P, Leapman RD, Arthur LO, Earl PL, Moss B, Lebowitz J. Oligomeric structure of virion-associated and soluble forms of the simian immunodeficiency virus envelope protein in the prefusion activated conformation. Proc Natl Acad Sci U S A 2001; 98:14877-82. [PMID: 11752436 PMCID: PMC64952 DOI: 10.1073/pnas.261573898] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The envelope proteins (env) of simian immunodeficiency virus (SIV) and HIV type 1 assemble to form noncovalently associated oligomers in the endoplasmic reticulum. After cleavage in a Golgi compartment, oligomeric env complexes are transported to the surface of infected cells, where incorporation into budding virions can occur. Difficulties in obtaining adequate quantities of virions retaining env, as well as the unstable nature and hydrophobicity of the oligomer, may account for the absence of previous biophysical studies to determine the oligomeric valency of membrane-associated env. The aim of this study was to evaluate the oligomeric state of SIV env before membrane-fusion activation. Virion-associated env, obtained by crosslinking and detergent extraction, and non-crosslinked secreted env ectodomain (recombinant gp140) were purified by lentil-lectin chromatography and gel filtration as single predominant species. Sedimentation equilibrium-derived mass values for both forms of SIV env were close to those predicted for trimeric assemblies. Determination of the mass of individual molecules by scanning transmission electron microscopy confirmed that SIV virion-associated env and gp140 formed largely homogeneous populations of trimers. Furthermore, a triangular or tri-lobed morphology was clearly visualized in a subset of the trimers.
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Affiliation(s)
- R J Center
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, and Division of Bioengineering and Physical Science, Office of Research Services, National Institutes of Health, Bethesda, MD 20892, USA
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36
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Maerz AL, Center RJ, Kemp BE, Kobe B, Poumbourios P. Functional implications of the human T-lymphotropic virus type 1 transmembrane glycoprotein helical hairpin structure. J Virol 2000; 74:6614-21. [PMID: 10864675 PMCID: PMC112171 DOI: 10.1128/jvi.74.14.6614-6621.2000] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Retrovirus entry into cells follows receptor binding by the surface-exposed envelope glycoprotein (Env) subunit (SU), which triggers the membrane fusion activity of the transmembrane (TM) protein. TM protein fragments expressed in the absence of SU adopt helical hairpin structures comprising a central coiled coil, a region of chain reversal containing a disulfide-bonded loop, and a C-terminal segment that packs onto the exterior of the coiled coil in an antiparallel manner. Here we used in vitro mutagenesis to test the functional role of structural elements observed in a model helical hairpin, gp21 of human T-lymphotropic virus type 1. Membrane fusion activity requires the stabilization of the N and C termini of the central coiled coil by a hydrophobic N cap and a small hydrophobic core, respectively. A conserved Gly-Gly hinge motif preceding the disulfide-bonded loop, a salt bridge that stabilizes the chain reversal region, and interactions between the C-terminal segment and the coiled coil are also critical for fusion activity. Our data support a model whereby the chain reversal region transmits a conformational signal from receptor-bound SU to induce the fusion-activated helical hairpin conformation of the TM protein.
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MESH Headings
- Cell Line
- Cell Membrane/chemistry
- Cell Membrane/metabolism
- Gene Products, env/chemistry
- Gene Products, env/genetics
- Gene Products, env/metabolism
- Gene Products, env/physiology
- HeLa Cells
- Human T-lymphotropic virus 1/chemistry
- Human T-lymphotropic virus 1/metabolism
- Human T-lymphotropic virus 1/physiology
- Humans
- Membrane Fusion
- Models, Molecular
- Mutagenesis, Site-Directed
- Protein Conformation
- Protein Structure, Tertiary
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/physiology
- Retroviridae Proteins, Oncogenic/chemistry
- Retroviridae Proteins, Oncogenic/genetics
- Retroviridae Proteins, Oncogenic/metabolism
- Retroviridae Proteins, Oncogenic/physiology
- env Gene Products, Human Immunodeficiency Virus
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Affiliation(s)
- A L Maerz
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia
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37
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Abstract
The envelope protein of human immunodeficiency virus type 1 HIV-1 undergoes proteolytic cleavage in the Golgi complex to produce subunits designated gp120 and gp41, which remain noncovalently associated. While gp41 has a well-characterized oligomeric structure, the maintenance of gp41-independent gp120 intersubunit contacts remains a contentious issue. Using recombinant vaccinia virus to achieve high-level expression of gp120 in mammalian cells combined with gel filtration analysis, we were able to isolate a discrete oligomeric form of gp120. Oligomerization of gp120 occurred intracellularly between 30 and 120 min after synthesis. Analysis by sedimentation equilibrium unequivocally identified the oligomeric species as a dimer. In order to identify the domains involved in the intersubunit contact, we expressed a series of gp120 proteins lacking various domains and assessed the effects of mutation on oligomeric structure. Deletion of the V1 or V3 loops had little effect on the relative amounts of monomer and dimer in comparison to wild-type gp120. In contrast, deletion of either all or part of the V2 loop drastically reduced dimer formation, indicating that this domain is required for intersubunit contact formation. Consistent with this, the V2 loop of the dimer was less accessible than that of the monomer to a specific monoclonal antibody. Previous studies have shown that while the V2 loop is not an absolute requirement for viral entry, the absence of this domain reduces viral resistance to neutralization by monoclonal antibodies or sera. We propose that the quaternary structure of gp120 may contribute to resistance to neutralization by limiting the exposure of conserved epitopes.
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Affiliation(s)
- R J Center
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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38
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Abstract
Recent structural studies of proteins mediating membrane fusion reveal intriguing similarities between diverse viral and mammalian systems. Particularly striking is the close similarity between the transmembrane envelope glycoproteins from the retrovirus HTLV-1 and the filovirus Ebola. These similarities suggest similar mechanisms of membrane fusion. The model that fits most currently available data suggests fusion activation in viral systems is driven by a symmetrical conformational change triggered by an activation event such as receptor binding or a pH change. The mammalian vesicle fusion mediated by the SNARE protein complex most likely occurs by a similar mechanism but without symmetry constraints.
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Affiliation(s)
- P Poumbourios
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia
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39
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Poumbourios P, Center RJ, Wilson KA, Kemp BE, Kobe B. Evolutionary Conservation of the Membrane Fusion Machine. IUBMB Life 1999. [DOI: 10.1080/152165499307152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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40
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Kobe B, Center RJ, Kemp BE, Poumbourios P. Crystal structure of human T cell leukemia virus type 1 gp21 ectodomain crystallized as a maltose-binding protein chimera reveals structural evolution of retroviral transmembrane proteins. Proc Natl Acad Sci U S A 1999; 96:4319-24. [PMID: 10200260 PMCID: PMC16330 DOI: 10.1073/pnas.96.8.4319] [Citation(s) in RCA: 176] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Retroviral entry into cells depends on envelope glycoproteins, whereby receptor binding to the surface-exposed subunit triggers membrane fusion by the transmembrane protein (TM) subunit. We determined the crystal structure at 2.5-A resolution of the ectodomain of gp21, the TM from human T cell leukemia virus type 1. The gp21 fragment was crystallized as a maltose-binding protein chimera, and the maltose-binding protein domain was used to solve the initial phases by the method of molecular replacement. The structure of gp21 comprises an N-terminal trimeric coiled coil, an adjacent disulfide-bonded loop that stabilizes a chain reversal, and a C-terminal sequence structurally distinct from HIV type 1/simian immunodeficiency virus gp41 that packs against the coil in an extended antiparallel fashion. Comparison of the gp21 structure with the structures of other retroviral TMs contrasts the conserved nature of the coiled coil-forming region and adjacent disulfide-bonded loop with the variable nature of the C-terminal ectodomain segment. The structure points to these features having evolved to enable the dual roles of retroviral TMs: conserved fusion function and an ability to anchor diverse surface-exposed subunit structures to the virion envelope and infected cell surface. The structure of gp21 implies that the N-terminal fusion peptide is in close proximity to the C-terminal transmembrane domain and likely represents a postfusion conformation.
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MESH Headings
- Amino Acid Sequence
- Carrier Proteins/chemistry
- Carrier Proteins/isolation & purification
- Computer Graphics
- Crystallization
- Crystallography, X-Ray/methods
- Evolution, Molecular
- Gene Products, env/chemistry
- Gene Products, env/genetics
- Gene Products, env/isolation & purification
- Human T-lymphotropic virus 1/chemistry
- Human T-lymphotropic virus 1/genetics
- Humans
- Macromolecular Substances
- Maltose-Binding Proteins
- Models, Molecular
- Molecular Sequence Data
- Protein Structure, Secondary
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/isolation & purification
- Retroviridae Proteins, Oncogenic/chemistry
- Retroviridae Proteins, Oncogenic/genetics
- Retroviridae Proteins, Oncogenic/isolation & purification
- Sequence Alignment
- Sequence Homology, Amino Acid
- env Gene Products, Human Immunodeficiency Virus
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Affiliation(s)
- B Kobe
- St. Vincent's Institute of Medical Research, 41 Victoria Parade, Fitzroy, Victoria 3065, Australia
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41
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Center RJ, Kobe B, Wilson KA, Teh T, Howlett GJ, Kemp BE, Poumbourios P. Crystallization of a trimeric human T cell leukemia virus type 1 gp21 ectodomain fragment as a chimera with maltose-binding protein. Protein Sci 1998; 7:1612-9. [PMID: 9684894 PMCID: PMC2144054 DOI: 10.1002/pro.5560070715] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We present a novel protein crystallization strategy, applied to the crystallization of human T cell leukemia virus type 1 (HTLV-1) transmembrane protein gp21 lacking the fusion peptide and the transmembrane domain, as a chimera with the Escherichia coli maltose binding protein (MBP). Crystals could not be obtained with a MBP/gp21 fusion protein in which fusion partners were separated by a flexible linker, but were obtained after connecting the MBP C-terminal alpha-helix to the predicted N-terminal alpha-helical sequence of gp21 via three alanine residues. The gp21 sequences conferred a trimeric structure to the soluble fusion proteins as assessed by sedimentation equilibrium and X-ray diffraction, consistent with the trimeric structures of other retroviral transmembrane proteins. The envelope protein precursor, gp62, is likewise trimeric when expressed in mammalian cells. Our results suggest that MBP may have a general application for the crystallization of proteins containing N-terminal alpha-helical sequences.
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Affiliation(s)
- R J Center
- St. Vincent's Institute of Medical Research, Fitzroy, Australia
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42
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Abstract
Hetero-oligomerization between human immunodeficiency virus type 2 (HIV-2) envelope glycoprotein (Env) truncation mutants and epitope-tagged gp160 is dependent on the presence of gp41 transmembrane protein (TM) amino acids 552 to 589, a putative amphipathic alpha-helical sequence. HIV-2 Env truncation mutants containing this sequence were also able to form cross-type hetero-oligomers with HIV-1 Env. HIV-2/HIV-1 hetero-oligomerization was, however, more sensitive to disruption by mutagenesis or increased temperature. The conservation of the Env oligomerization function of the HIV-1 and HIV-2 alpha-helical sequences suggests that retroviral TM alpha-helical motifs may have a universal role in oligomerization.
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Affiliation(s)
- R J Center
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia
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43
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Poumbourios P, Wilson KA, Center RJ, El Ahmar W, Kemp BE. Human immunodeficiency virus type 1 envelope glycoprotein oligomerization requires the gp41 amphipathic alpha-helical/leucine zipper-like sequence. J Virol 1997; 71:2041-9. [PMID: 9032336 PMCID: PMC191291 DOI: 10.1128/jvi.71.3.2041-2049.1997] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) oligomerization was investigated by coexpressing wild-type and truncated envelope glycoproteins to determine the minimum sequence required for mutant-wild-type hetero-oligomerization. The gp41 putative amphipathic alpha-helix, Leu-550 to Leu-582, was essential for hetero-oligomer formation. Alanine substitution of 9 of the 10 residues composing the gp41 amphipathic alpha-helix 4-3 hydrophobic repeat sequence was required to inhibit mutant-wild-type hetero-oligomerization and to render the envelope glycoprotein precursor, gp160, monomeric. This indicates that multiple hydrophobic contacts contribute to the stable envelope glycoprotein oligomeric structure. Single alanine substitutions within the hydrophobic repeat sequence did not affect gp160 oligomeric structure but abolished syncytium-forming function. Some mutations also diminished gp160 processing efficiency and the association between gp120 and gp41 in a position-dependent manner. These results indicate that the gp41 amphipathic alpha-helix 4-3 hydrophobic repeat sequence plays a central role in HIV-1 envelope glycoprotein oligomerization and fusion function.
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Affiliation(s)
- P Poumbourios
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia.
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44
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Sexton PM, Houssami S, Hilton JM, O'Keeffe LM, Center RJ, Gillespie MT, Darcy P, Findlay DM. Identification of brain isoforms of the rat calcitonin receptor. Mol Endocrinol 1993; 7:815-21. [PMID: 8395656 DOI: 10.1210/mend.7.6.8395656] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Two rat calcitonin receptor isoforms have been identified by cDNA cloning from a hypothalamic library. The clones, C1a and C1b, specified proteins of 478 and 515 amino acids, respectively. The clones were identical, except that the C1b sequence encoded a 37-amino acid insert in the second extracellular domain, which conferred altered ligand recognition. Compared to the C1a receptor, expressed C1b receptors exhibited decreased affinity for porcine CT, relative to salmon CT, and negligible affinity for human CT. Clone C1b mRNA was predominately expressed in the brain, whereas mRNA for the C1a clone was present in both brain and peripheral tissues. Both receptors were able to couple functionally to adenylate cyclase. Thus, clone C1b represents a novel brain isoform of the CT receptor with different affinity for CT analogs resulting from an altered second extracellular domain.
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Affiliation(s)
- P M Sexton
- St. Vincent's Institute of Medical Research Fitzroy, Victoria, Australia
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