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Walker MR, Idorn M, Bennett A, Søgaard M, Salanti A, Ditlev SB, Barfod L. Characterization of SARS-CoV-2 humoral immune response in a subject with unique sampling: A case report. Immun Inflamm Dis 2023; 11:e910. [PMID: 37382252 DOI: 10.1002/iid3.910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Revised: 05/23/2023] [Accepted: 05/26/2023] [Indexed: 06/30/2023] Open
Abstract
BACKGROUND The development of vaccine candidates for COVID-19, and the administration of booster vaccines, has meant a significant reduction in COVID-19 related deaths world-wide and the easing of global restrictions. However, new variants of SARS-CoV-2 have emerged with less susceptibility to vaccine induced immunity leading to breakthrough infections among vaccinated people. It is generally acknowledged that immunoglobulins play the major role in immune-protection, primarily through binding to the SARS-COV-2 receptor binding domain (RBD) and thereby inhibiting viral binding to the ACE2 receptor. However, there are limited investigations of anti-RBD isotypes (IgM, IgG, IgA) and IgG subclasses (IgG1-4) over the course of vaccination and breakthrough infection. METHOD In this study, SARS-CoV-2 humoral immunity is examined in a single subject with unique longitudinal sampling. Over a two year period, the subject received three doses of vaccine, had two active breakthrough infections and 22 blood samples collected. Serological testing included anti-nucleocapsid total antibodies, anti-RBD total antibodies, IgG, IgA, IgM and IgG subclasses, neutralization and ACE2 inhibition against the wildtype (WT), Delta and Omicron variants. RESULTS Vaccination and breakthrough infections induced IgG, specifically IgG1 and IgG4 as well as IgM and IgA. IgG1 and IgG4 responses were cross reactive and associated with broad inhibition. CONCLUSION The findings here provide novel insights into humoral immune response characteristics associated with SARS-CoV-2 breakthrough infections.
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Affiliation(s)
- Melanie R Walker
- Department of Immunology and Microbiology, Centre for Medical Parasitology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Manja Idorn
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Anja Bennett
- Department of Mammalian Expression, Global Research Technologies, Måløv, Denmark
| | - Max Søgaard
- Expres2ion Biotechnologies, Hørsholm, Denmark
| | - Ali Salanti
- Department of Immunology and Microbiology, Centre for Medical Parasitology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sisse B Ditlev
- Copenhagen Center for Translational Research, Bispebjerg Hospital, Copenhagen, Denmark
| | - Lea Barfod
- Department of Immunology and Microbiology, Centre for Medical Parasitology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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2
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Björnsson KH, Barfod L. A complex equation - adding to Plasmodium falciparum invasion. Trends Parasitol 2023; 39:160-162. [PMID: 36682939 DOI: 10.1016/j.pt.2023.01.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 01/12/2023] [Accepted: 01/12/2023] [Indexed: 01/22/2023]
Abstract
The Plasmodium falciparum invasion complex - consisting of the prime blood-stage vaccine candidates PfRH5, PfCyRPA and PfRipr - is essential and conserved. New data from Scally et al. reveal that the complex consists of two additional proteins, adding important knowledge to the current understanding of the biology behind the invasion process.
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Affiliation(s)
- Kasper H Björnsson
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lea Barfod
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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3
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Raghavan SSR, Dagil R, Lopez-Perez M, Conrad J, Bassi MR, Quintana MDP, Choudhary S, Gustavsson T, Wang Y, Gourdon P, Ofori MF, Christensen SB, Minja DTR, Schmiegelow C, Nielsen MA, Barfod L, Hviid L, Salanti A, Lavstsen T, Wang K. Cryo-EM reveals the conformational epitope of human monoclonal antibody PAM1.4 broadly reacting with polymorphic malarial protein VAR2CSA. PLoS Pathog 2022; 18:e1010924. [PMCID: PMC9668162 DOI: 10.1371/journal.ppat.1010924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 10/10/2022] [Indexed: 11/17/2022] Open
Abstract
Malaria during pregnancy is a major global health problem caused by infection with Plasmodium falciparum parasites. Severe effects arise from the accumulation of infected erythrocytes in the placenta. Here, erythrocytes infected by late blood-stage parasites adhere to placental chondroitin sulphate A (CS) via VAR2CSA-type P. falciparum erythrocyte membrane protein 1 (PfEMP1) adhesion proteins. Immunity to placental malaria is acquired through exposure and mediated through antibodies to VAR2CSA. Through evolution, the VAR2CSA proteins have diversified in sequence to escape immune recognition but retained their overall macromolecular structure to maintain CS binding affinity. This structural conservation may also have allowed development of broadly reactive antibodies to VAR2CSA in immune women. Here we show the negative stain and cryo-EM structure of the only known broadly reactive human monoclonal antibody, PAM1.4, in complex with VAR2CSA. The data shows how PAM1.4’s broad VAR2CSA reactivity is achieved through interactions with multiple conserved residues of different sub-domains forming conformational epitope distant from the CS binding site on the VAR2CSA core structure. Thus, while PAM1.4 may represent a class of antibodies mediating placental malaria immunity by inducing phagocytosis or NK cell-mediated cytotoxicity, it is likely that broadly CS binding-inhibitory antibodies target other epitopes at the CS binding site. Insights on both types of broadly reactive monoclonal antibodies may aid the development of a vaccine against placental malaria.
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Affiliation(s)
- Sai Sundar Rajan Raghavan
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Robert Dagil
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Mary Lopez-Perez
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Julian Conrad
- Swedish National Cryo-EM Facility, Science for Life Laboratories, Solna, Sweden
| | - Maria Rosaria Bassi
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Maria del Pilar Quintana
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Swati Choudhary
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Tobias Gustavsson
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Yong Wang
- Joint Research Centre for Engineering Biology, Zhejiang University-University of Edinburgh Institute, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Pontus Gourdon
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Michael Fokuo Ofori
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Sebastian Boje Christensen
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | | | - Christentze Schmiegelow
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Morten Agertoug Nielsen
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Lea Barfod
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Lars Hviid
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Ali Salanti
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Thomas Lavstsen
- Centre for Medical Parasitology at Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, and Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
- * E-mail: (TL); (KW)
| | - Kaituo Wang
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
- * E-mail: (TL); (KW)
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4
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Knudsen AS, Walker MR, Agullet JP, Björnsson KH, Bassi MR, Barfod L. Enhancing neutralization of Plasmodium falciparum using a novel monoclonal antibody against the rhoptry-associated membrane antigen. Sci Rep 2022; 12:3040. [PMID: 35197516 PMCID: PMC8866459 DOI: 10.1038/s41598-022-06921-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 08/19/2021] [Accepted: 01/31/2022] [Indexed: 11/09/2022] Open
Abstract
The pathogenesis of malaria is associated with blood-stage infection and there is strong evidence that antibodies specific to parasite blood-stage antigens can control parasitemia. This provides a strong rational for applying blood-stage antigen components in a multivalent vaccine, as the induced antibodies in combination can enhance protection. The Plasmodium falciparum rhoptry-associated membrane antigen (PfRAMA) is a promising vaccine target, due to its fundamental role in merozoite invasion and low level of polymorphism. Polyclonal antibodies against PfRAMA are able to inhibit P. falciparum growth and interact synergistically when combined with antibodies against P. falciparum reticulocyte-binding protein 5 (PfRh5) or cysteine-rich protective antigen (PfCyRPA). In this study, we identified a novel PfRAMA-specific mAb with neutralizing activity, which in combination with PfRh5- or PfCyRPA-specific mAbs potentiated the neutralizing effect. By applying phage display technology, we mapped the protective epitope to be in the C-terminal region of PfRAMA. Our results confirmed previous finding of synergy between PfRAMA-, PfRh5- and PfCyRPA-specific antibodies, thereby paving the way of testing these antigens (or fragments of these antigens) in combination to improve the efficacy of blood-stage malaria vaccines. The results emphasize the importance of directing antibody responses towards protective epitopes, as the majority of anti-PfRAMA mAbs were unable to inhibit merozoite invasion of erythrocytes.
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Affiliation(s)
- Anne S Knudsen
- Department of Immunology and Microbiology, Centre for Medical Parasitology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Melanie R Walker
- Department of Immunology and Microbiology, Centre for Medical Parasitology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Judit P Agullet
- Department of Immunology and Microbiology, Centre for Medical Parasitology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kasper H Björnsson
- Department of Immunology and Microbiology, Centre for Medical Parasitology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Maria R Bassi
- Department of Immunology and Microbiology, Centre for Medical Parasitology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lea Barfod
- Department of Immunology and Microbiology, Centre for Medical Parasitology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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5
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Walker MR, Barfod L. Production of PfEMP1-Specific Human Monoclonal Antibodies from Naturally Immune Individuals. Methods Mol Biol 2022; 2470:407-421. [PMID: 35881362 DOI: 10.1007/978-1-0716-2189-9_30] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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] [Indexed: 06/15/2023]
Abstract
Plasmodium falciparum parasites express variable surface antigens on the infected erythrocyte surface allowing adhesion to human host receptors on the blood and endothelial cells, which can result in immune evasion. One of the most studied and key antigens in adhesion is the highly polymorphic PfEMP1. However, despite the vast variation in the PfEMP1 antigens, they are the main targets of naturally acquired immunity and are therefore promising candidates for malaria vaccine development. Generating PfEMP1-specific human monoclonal antibodies from naturally immune individuals will help to determine the best targets of protection from clinical disease. Immortalization of human B cells is one of the oldest and most efficient techniques to generate human monoclonal antibodies. Nevertheless, most protocols require flow cytometry-based cell sorting, which can be a limiting factor for many laboratories. This chapter describes an efficient protocol for the generation of PfEMP1-specific human monoclonal antibodies from malaria immune individuals that can be performed without the use of advanced cell-sorting techniques.
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Affiliation(s)
- Melanie R Walker
- Centre for Medical Parasitology at Department of Immunology and Microbiology (ISIM), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases Copenhagen, University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Lea Barfod
- Centre for Medical Parasitology at Department of Immunology and Microbiology (ISIM), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
- Department of Infectious Diseases Copenhagen, University Hospital (Rigshospitalet), Copenhagen, Denmark.
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6
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Dalgaard N, Barfod L. Production of PfEMP1-Specific Mouse Monoclonal Antibodies. Methods Mol Biol 2022; 2470:391-405. [PMID: 35881361 DOI: 10.1007/978-1-0716-2189-9_29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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] [Indexed: 06/15/2023]
Abstract
The PfEMP1 family of proteins expressed on the Plasmodium falciparum-infected erythrocyte (IE) surface is the main target of naturally acquired immunity against malaria. Antibodies capable of opsonizing the IEs and blocking the binding between PfEMP1 and human receptors seems to be one of the main protective mechanisms of the naturally acquired immunity. Therefore this family of antigens is intensively studied. Monoclonal antibodies (mAbs) are a very valuable research tool for studying this diverse family of proteins and their interaction with human receptors. As examples, mAbs can be used to identify protective epitopes, epitopes that are targets of cross-reactive antibodies, and the surface expression of specific PfEMP1 variants. Fusing mouse splenocytes with myeloma cells to generate long-lived antibody secreting hybridoma cell lines have been used since the 1970s for the production of mAbs. In this chapter, we describe a simple, reliable, and relatively fast method for producing PfEMP1-specific mAbs from mouse spleen cells using semisolid HAT selection medium.
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Affiliation(s)
- Nanna Dalgaard
- Centre for Medical Parasitology at Department of Immunology and Microbiology (ISIM), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lea Barfod
- Centre for Medical Parasitology at Department of Immunology and Microbiology (ISIM), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
- Department of Infectious Diseases Copenhagen, University Hospital (Rigshospitalet), Copenhagen, Denmark.
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7
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Knudsen AS, Björnsson KH, Bassi MR, Walker MR, Kok A, Cristinoi B, Jensen AR, Barfod L. Strain-Dependent Inhibition of Erythrocyte Invasion by Monoclonal Antibodies Against Plasmodium falciparum CyRPA. Front Immunol 2021; 12:716305. [PMID: 34447381 PMCID: PMC8383283 DOI: 10.3389/fimmu.2021.716305] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [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] [Received: 05/28/2021] [Accepted: 07/14/2021] [Indexed: 12/01/2022] Open
Abstract
The highly conserved Plasmodium falciparum cysteine-rich protective antigen (PfCyRPA) is a key target for next-generation vaccines against blood-stage malaria. PfCyRPA constitute the core of a ternary complex, including the reticulocyte binding-like homologous protein 5 (PfRh5) and the Rh5-interacting protein (PfRipr), and is fundamental for merozoite invasion of erythrocytes. In this study, we show that monoclonal antibodies (mAbs) specific to PfCyRPA neutralize the in vitro growth of Ghanaian field isolates as well as numerous laboratory-adapted parasite lines. We identified subsets of mAbs with neutralizing activity that bind to distinct sites on PfCyRPA and that in combination potentiate the neutralizing effect. As antibody responses against multiple merozoite invasion proteins are thought to improve the efficacy of blood-stage vaccines, we also demonstrated that combinations of PfCyRPA- and PfRh5 specific mAbs act synergistically to neutralize parasite growth. Yet, we identified prominent strain-dependent neutralization potencies, which our results suggest is independent of PfCyRPA expression level and polymorphism, demonstrating the importance of addressing functional converseness when evaluating blood-stage vaccine candidates. Finally, our results suggest that blood-stage vaccine efficacy can be improved by directing the antibody response towards defined protective epitopes on multiple parasite antigens.
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Affiliation(s)
- Anne S Knudsen
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kasper H Björnsson
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Maria R Bassi
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Melanie R Walker
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Andreas Kok
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Bogdan Cristinoi
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anja R Jensen
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lea Barfod
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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8
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Minassian AM, Silk SE, Barrett JR, Nielsen CM, Miura K, Diouf A, Loos C, Fallon JK, Michell AR, White MT, Edwards NJ, Poulton ID, Mitton CH, Payne RO, Marks M, Maxwell-Scott H, Querol-Rubiera A, Bisnauthsing K, Batra R, Ogrina T, Brendish NJ, Themistocleous Y, Rawlinson TA, Ellis KJ, Quinkert D, Baker M, Lopez Ramon R, Ramos Lopez F, Barfod L, Folegatti PM, Silman D, Datoo M, Taylor IJ, Jin J, Pulido D, Douglas AD, de Jongh WA, Smith R, Berrie E, Noe AR, Diggs CL, Soisson LA, Ashfield R, Faust SN, Goodman AL, Lawrie AM, Nugent FL, Alter G, Long CA, Draper SJ. Reduced blood-stage malaria growth and immune correlates in humans following RH5 vaccination. Med 2021; 2:701-719.e19. [PMID: 34223402 PMCID: PMC8240500 DOI: 10.1016/j.medj.2021.03.014] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 02/19/2021] [Accepted: 03/25/2021] [Indexed: 12/27/2022]
Abstract
BACKGROUND Development of an effective vaccine against the pathogenic blood-stage infection of human malaria has proved challenging, and no candidate vaccine has affected blood-stage parasitemia following controlled human malaria infection (CHMI) with blood-stage Plasmodium falciparum. METHODS We undertook a phase I/IIa clinical trial in healthy adults in the United Kingdom of the RH5.1 recombinant protein vaccine, targeting the P. falciparum reticulocyte-binding protein homolog 5 (RH5), formulated in AS01B adjuvant. We assessed safety, immunogenicity, and efficacy against blood-stage CHMI. Trial registered at ClinicalTrials.gov, NCT02927145. FINDINGS The RH5.1/AS01B formulation was administered using a range of RH5.1 protein vaccine doses (2, 10, and 50 μg) and was found to be safe and well tolerated. A regimen using a delayed and fractional third dose, in contrast to three doses given at monthly intervals, led to significantly improved antibody response longevity over ∼2 years of follow-up. Following primary and secondary CHMI of vaccinees with blood-stage P. falciparum, a significant reduction in parasite growth rate was observed, defining a milestone for the blood-stage malaria vaccine field. We show that growth inhibition activity measured in vitro using purified immunoglobulin G (IgG) antibody strongly correlates with in vivo reduction of the parasite growth rate and also identify other antibody feature sets by systems serology, including the plasma anti-RH5 IgA1 response, that are associated with challenge outcome. CONCLUSIONS Our data provide a new framework to guide rational design and delivery of next-generation vaccines to protect against malaria disease. FUNDING This study was supported by USAID, UK MRC, Wellcome Trust, NIAID, and the NIHR Oxford-BRC.
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Affiliation(s)
| | - Sarah E. Silk
- The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | | | | | - Kazutoyo Miura
- Laboratory of Malaria and Vector Research, NIAID/NIH, Rockville, MD 20852, USA
| | - Ababacar Diouf
- Laboratory of Malaria and Vector Research, NIAID/NIH, Rockville, MD 20852, USA
| | - Carolin Loos
- The Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA 02139, USA
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | | | - Ashlin R. Michell
- The Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA 02139, USA
| | - Michael T. White
- Department of Parasites and Insect Vectors, Institut Pasteur, 25-28 Rue du Dr Roux, 75015 Paris, France
| | - Nick J. Edwards
- The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Ian D. Poulton
- The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Celia H. Mitton
- The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Ruth O. Payne
- The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Michael Marks
- Centre for Clinical Infection and Diagnostics Research, King’s College London and Guy’s & St Thomas’ NHS Foundation Trust, Westminster Bridge Road, London SE1 7EH, UK
| | - Hector Maxwell-Scott
- Centre for Clinical Infection and Diagnostics Research, King’s College London and Guy’s & St Thomas’ NHS Foundation Trust, Westminster Bridge Road, London SE1 7EH, UK
| | - Antonio Querol-Rubiera
- Centre for Clinical Infection and Diagnostics Research, King’s College London and Guy’s & St Thomas’ NHS Foundation Trust, Westminster Bridge Road, London SE1 7EH, UK
| | - Karen Bisnauthsing
- Centre for Clinical Infection and Diagnostics Research, King’s College London and Guy’s & St Thomas’ NHS Foundation Trust, Westminster Bridge Road, London SE1 7EH, UK
| | - Rahul Batra
- Centre for Clinical Infection and Diagnostics Research, King’s College London and Guy’s & St Thomas’ NHS Foundation Trust, Westminster Bridge Road, London SE1 7EH, UK
| | - Tatiana Ogrina
- NIHR Wellcome Trust Clinical Research Facility, University Hospital Southampton NHS Foundation Trust, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK
| | - Nathan J. Brendish
- NIHR Wellcome Trust Clinical Research Facility, University Hospital Southampton NHS Foundation Trust, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK
| | | | | | | | - Doris Quinkert
- The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Megan Baker
- The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | | | | | - Lea Barfod
- The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | | | - Daniel Silman
- The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Mehreen Datoo
- The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Iona J. Taylor
- The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Jing Jin
- The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - David Pulido
- The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | | | - Willem A. de Jongh
- ExpreSion Biotechnologies, SCION-DTU Science Park, Agern Allé 1, Hørsholm 2970, Denmark
| | - Robert Smith
- Clinical BioManufacturing Facility, University of Oxford, Oxford OX3 7JT, UK
| | - Eleanor Berrie
- Clinical BioManufacturing Facility, University of Oxford, Oxford OX3 7JT, UK
| | | | | | | | | | - Saul N. Faust
- NIHR Wellcome Trust Clinical Research Facility, University Hospital Southampton NHS Foundation Trust, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK
| | - Anna L. Goodman
- Centre for Clinical Infection and Diagnostics Research, King’s College London and Guy’s & St Thomas’ NHS Foundation Trust, Westminster Bridge Road, London SE1 7EH, UK
| | | | - Fay L. Nugent
- The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Galit Alter
- The Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA 02139, USA
| | - Carole A. Long
- Laboratory of Malaria and Vector Research, NIAID/NIH, Rockville, MD 20852, USA
| | - Simon J. Draper
- The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
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9
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Illingworth JJ, Alanine DG, Brown R, Marshall JM, Bartlett HE, Silk SE, Labbé GM, Quinkert D, Cho JS, Wendler JP, Pattinson DJ, Barfod L, Douglas AD, Shea MW, Wright KE, de Cassan SC, Higgins MK, Draper SJ. Functional Comparison of Blood-Stage Plasmodium falciparum Malaria Vaccine Candidate Antigens. Front Immunol 2019; 10:1254. [PMID: 31214195 PMCID: PMC6558156 DOI: 10.3389/fimmu.2019.01254] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [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] [Received: 12/21/2018] [Accepted: 05/17/2019] [Indexed: 12/22/2022] Open
Abstract
The malaria genome encodes over 5,000 proteins and many of these have also been proposed to be potential vaccine candidates, although few of these have been tested clinically. RH5 is one of the leading blood-stage Plasmodium falciparum malaria vaccine antigens and Phase I/II clinical trials of vaccines containing this antigen are currently underway. Its likely mechanism of action is to elicit antibodies that can neutralize merozoites by blocking their invasion of red blood cells (RBC). However, many other antigens could also elicit neutralizing antibodies against the merozoite, and most of these have never been compared directly to RH5. The objective of this study was to compare a range of blood-stage antigens to RH5, to identify any antigens that outperform or synergize with anti-RH5 antibodies. We selected 55 gene products, covering 15 candidate antigens that have been described in the literature and 40 genes selected on the basis of bioinformatics functional prediction. We were able to make 20 protein-in-adjuvant vaccines from the original selection. Of these, S-antigen and CyRPA robustly elicited antibodies with neutralizing properties. Anti-CyRPA IgG generally showed additive GIA with anti-RH5 IgG, although high levels of anti-CyRPA-specific rabbit polyclonal IgG were required to achieve 50% GIA. Our data suggest that further vaccine antigen screening efforts are required to identify a second merozoite target with similar antibody-susceptibility to RH5.
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Affiliation(s)
| | | | - Rebecca Brown
- Jenner Institute, University of Oxford, Oxford, United Kingdom
| | | | | | - Sarah E Silk
- Jenner Institute, University of Oxford, Oxford, United Kingdom
| | | | - Doris Quinkert
- Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Jee Sun Cho
- Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Jason P Wendler
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | | | - Lea Barfod
- Jenner Institute, University of Oxford, Oxford, United Kingdom
| | | | - Michael W Shea
- Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Katherine E Wright
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | | | - Matthew K Higgins
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Simon J Draper
- Jenner Institute, University of Oxford, Oxford, United Kingdom
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10
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Partey FD, Castberg FC, Sarbah EW, Silk SE, Awandare GA, Draper SJ, Opoku N, Kweku M, Ofori MF, Hviid L, Barfod L. Correction: Kinetics of antibody responses to PfRH5-complex antigens in Ghanaian children with Plasmodium falciparum malaria. PLoS One 2018; 13:e0204452. [PMID: 30222763 PMCID: PMC6141069 DOI: 10.1371/journal.pone.0204452] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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11
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Payne RO, Silk SE, Elias SC, Miura K, Diouf A, Galaway F, de Graaf H, Brendish NJ, Poulton ID, Griffiths OJ, Edwards NJ, Jin J, Labbé GM, Alanine DG, Siani L, Di Marco S, Roberts R, Green N, Berrie E, Ishizuka AS, Nielsen CM, Bardelli M, Partey FD, Ofori MF, Barfod L, Wambua J, Murungi LM, Osier FH, Biswas S, McCarthy JS, Minassian AM, Ashfield R, Viebig NK, Nugent FL, Douglas AD, Vekemans J, Wright GJ, Faust SN, Hill AV, Long CA, Lawrie AM, Draper SJ. Human vaccination against RH5 induces neutralizing antimalarial antibodies that inhibit RH5 invasion complex interactions. JCI Insight 2017; 2:96381. [PMID: 29093263 PMCID: PMC5752323 DOI: 10.1172/jci.insight.96381] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [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: 07/31/2017] [Accepted: 10/05/2017] [Indexed: 11/17/2022] Open
Abstract
The development of a highly effective vaccine remains a key strategic goal to aid the control and eventual eradication of Plasmodium falciparum malaria. In recent years, the reticulocyte-binding protein homolog 5 (RH5) has emerged as the most promising blood-stage P. falciparum candidate antigen to date, capable of conferring protection against stringent challenge in Aotus monkeys. We report on the first clinical trial to our knowledge to assess the RH5 antigen - a dose-escalation phase Ia study in 24 healthy, malaria-naive adult volunteers. We utilized established viral vectors, the replication-deficient chimpanzee adenovirus serotype 63 (ChAd63), and the attenuated orthopoxvirus modified vaccinia virus Ankara (MVA), encoding RH5 from the 3D7 clone of P. falciparum. Vaccines were administered i.m. in a heterologous prime-boost regimen using an 8-week interval and were well tolerated. Vaccine-induced anti-RH5 serum antibodies exhibited cross-strain functional growth inhibition activity (GIA) in vitro, targeted linear and conformational epitopes within RH5, and inhibited key interactions within the RH5 invasion complex. This is the first time to our knowledge that substantial RH5-specific responses have been induced by immunization in humans, with levels greatly exceeding the serum antibody responses observed in African adults following years of natural malaria exposure. These data support the progression of RH5-based vaccines to human efficacy testing.
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Affiliation(s)
- Ruth O. Payne
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Sarah E. Silk
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Sean C. Elias
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Kazutoyo Miura
- Laboratory of Malaria and Vector Research, NIAID/NIH, Rockville, Maryland, USA
| | - Ababacar Diouf
- Laboratory of Malaria and Vector Research, NIAID/NIH, Rockville, Maryland, USA
| | - Francis Galaway
- Cell Surface Signalling Laboratory, Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Hans de Graaf
- NIHR Wellcome Trust Clinical Research Facility, University Hospital Southampton NHS Foundation Trust and Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Nathan J. Brendish
- NIHR Wellcome Trust Clinical Research Facility, University Hospital Southampton NHS Foundation Trust and Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Ian D. Poulton
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | | | - Nick J. Edwards
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Jing Jin
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | | | | | - Loredana Siani
- ReiThera SRL (formerly Okairos SRL), Viale Città d’Europa, Rome, Italy
| | - Stefania Di Marco
- ReiThera SRL (formerly Okairos SRL), Viale Città d’Europa, Rome, Italy
| | - Rachel Roberts
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Nicky Green
- Clinical Biomanufacturing Facility, University of Oxford, Oxford, United Kingdom
| | - Eleanor Berrie
- Clinical Biomanufacturing Facility, University of Oxford, Oxford, United Kingdom
| | | | | | - Martino Bardelli
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Frederica D. Partey
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
- Centre for Medical Parasitology, Department of Immunology and Microbiology (ISIM), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Michael F. Ofori
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Lea Barfod
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Juliana Wambua
- KEMRI Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Linda M. Murungi
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
- KEMRI Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Faith H. Osier
- KEMRI Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Sumi Biswas
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - James S. McCarthy
- QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | | | - Rebecca Ashfield
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Nicola K. Viebig
- European Vaccine Initiative, UniversitätsKlinikum Heidelberg, Heidelberg, Germany
| | - Fay L. Nugent
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | | | | | - Gavin J. Wright
- Cell Surface Signalling Laboratory, Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Saul N. Faust
- NIHR Wellcome Trust Clinical Research Facility, University Hospital Southampton NHS Foundation Trust and Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Adrian V.S. Hill
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Carole A. Long
- Laboratory of Malaria and Vector Research, NIAID/NIH, Rockville, Maryland, USA
| | - Alison M. Lawrie
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Simon J. Draper
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
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Stevenson L, Laursen E, Cowan GJ, Bandoh B, Barfod L, Cavanagh DR, Andersen GR, Hviid L. α2-Macroglobulin Can Crosslink Multiple Plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1) Molecules and May Facilitate Adhesion of Parasitized Erythrocytes. PLoS Pathog 2015; 11:e1005022. [PMID: 26134405 PMCID: PMC4489720 DOI: 10.1371/journal.ppat.1005022] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [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: 01/12/2015] [Accepted: 06/12/2015] [Indexed: 11/19/2022] Open
Abstract
Rosetting, the adhesion of Plasmodium falciparum-infected erythrocytes to uninfected erythrocytes, involves clonal variants of the parasite protein P. falciparum erythrocyte membrane protein 1 (PfEMP1) and soluble serum factors. While rosetting is a well-known phenotypic marker of parasites associated with severe malaria, the reason for this association remains unclear, as do the molecular details of the interaction between the infected erythrocyte (IE) and the adhering erythrocytes. Here, we identify for the first time a single serum factor, the abundant serum protease inhibitor α2-macroglobulin (α2M), which is both required and sufficient for rosetting mediated by the PfEMP1 protein HB3VAR06 and some other rosette-mediating PfEMP1 proteins. We map the α2M binding site to the C terminal end of HB3VAR06, and demonstrate that α2M can bind at least four HB3VAR06 proteins, plausibly augmenting their combined avidity for host receptors. IgM has previously been identified as a rosette-facilitating soluble factor that acts in a similar way, but it cannot induce rosetting on its own. This is in contrast to α2M and probably due to the more limited cross-linking potential of IgM. Nevertheless, we show that IgM works synergistically with α2M and markedly lowers the concentration of α2M required for rosetting. Finally, HB3VAR06+ IEs share the capacity to bind α2M with subsets of genotypically distinct P. falciparum isolates forming rosettes in vitro and of patient parasite isolates ex vivo. Together, our results are evidence that P. falciparum parasites exploit α2M (and IgM) to expand the repertoire of host receptors available for PfEMP1-mediated IE adhesion, such as the erythrocyte carbohydrate moieties that lead to formation of rosettes. It is likely that this mechanism also affects IE adhesion to receptors on vascular endothelium. The study opens opportunities for broad-ranging immunological interventions targeting the α2M--(and IgM-) binding domains of PfEMP1, which would be independent of the host receptor specificity of clinically important PfEMP1 antigens.
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Affiliation(s)
- Liz Stevenson
- Centre for Medical Parasitology, Department of Immunology and Microbiology (ISIM), Faculty of Health and Medical Sciences, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Erik Laursen
- Centre for Medical Parasitology, Department of Immunology and Microbiology (ISIM), Faculty of Health and Medical Sciences, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Graeme J. Cowan
- Institute of Immunology and Infection Research, Center for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh, United Kingdom
| | - Betty Bandoh
- Centre for Medical Parasitology, Department of Immunology and Microbiology (ISIM), Faculty of Health and Medical Sciences, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Lea Barfod
- Centre for Medical Parasitology, Department of Immunology and Microbiology (ISIM), Faculty of Health and Medical Sciences, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - David R. Cavanagh
- Institute of Immunology and Infection Research, Center for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh, United Kingdom
| | - Gregers R. Andersen
- Department of Molecular Biology and Genetics, University of Aarhus, Aarhus, Denmark
| | - Lars Hviid
- Centre for Medical Parasitology, Department of Immunology and Microbiology (ISIM), Faculty of Health and Medical Sciences, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
- * E-mail:
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13
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Stevenson L, Huda P, Jeppesen A, Laursen E, Rowe JA, Craig A, Streicher W, Barfod L, Hviid L. Investigating the function of Fc-specific binding of IgM to Plasmodium falciparum erythrocyte membrane protein 1 mediating erythrocyte rosetting. Cell Microbiol 2015; 17:819-31. [PMID: 25482886 PMCID: PMC4737123 DOI: 10.1111/cmi.12403] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [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: 10/14/2014] [Revised: 11/28/2014] [Accepted: 12/01/2014] [Indexed: 02/02/2023]
Abstract
Acquired protection from Plasmodium falciparum malaria takes years to develop, probably reflecting the ability of the parasites to evade immunity. A recent example of this is the binding of the Fc region of IgM to VAR2CSA‐type PfEMP1. This interferes with specific IgG recognition and phagocytosis of opsonized infected erythrocytes (IEs) without compromising the placental IE adhesion mediated by this PfEMP1 type. IgM also binds via Fc to several other PfEMP1 proteins, where it has been proposed to facilitate rosetting (binding of uninfected erythrocytes to a central IE). To further dissect the functional role of Fc‐mediated IgM binding to PfEMP1, we studied the PfEMP1 protein HB3VAR06, which mediates rosetting and binds IgM. Binding of IgM to this PfEMP1 involved the Fc domains Cμ3‐Cμ4 in IgM and the penultimate DBL domain (DBLζ2) at the C‐terminus of HB3VAR06. However, IgM binding did not inhibit specific IgG labelling of HB3VAR06 or shield IgG‐opsonized IEs from phagocytosis. Instead, IgM was required for rosetting, and each pentameric IgM molecule could bind two HB3VAR06 molecules. Together, our data indicate that the primary function of Fc‐mediated IgM binding in rosetting is not to shield IE from specific IgG recognition and phagocytosis as in VAR2CSA‐type PfEMP1. Rather, the function appears to be strengthening of IE–erythrocyte interactions. In conclusion, our study provides new evidence on the molecular details and functional significance of rosetting, a long‐recognized marker of parasites that cause severe P. falciparum malaria.
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Affiliation(s)
- Liz Stevenson
- Centre for Medical Parasitology, Department of International Health, Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Pie Huda
- Niels Bohr Institute, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Anine Jeppesen
- Centre for Medical Parasitology, Department of International Health, Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Erik Laursen
- Centre for Medical Parasitology, Department of International Health, Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - J Alexandra Rowe
- Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, UK
| | - Alister Craig
- Liverpool School of Tropical Medicine, Liverpool, UK
| | - Werner Streicher
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lea Barfod
- Centre for Medical Parasitology, Department of International Health, Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Lars Hviid
- Centre for Medical Parasitology, Department of International Health, Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
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14
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Hviid L, Barfod L, Fowkes FJI. Trying to remember: immunological B cell memory to malaria. Trends Parasitol 2015; 31:89-94. [PMID: 25596801 DOI: 10.1016/j.pt.2014.12.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [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: 10/27/2014] [Revised: 12/16/2014] [Accepted: 12/17/2014] [Indexed: 11/17/2022]
Abstract
In areas with stable transmission of Plasmodium falciparum parasites, even partially-protective immunity to malaria is acquired only after years of exposure and several infections. It has long been speculated that malaria parasites are directly able to undermine the establishment and maintenance of immunological memory, and that the often transient antibody responses to this parasite are evidence of such a dysfunction. We propose that long-lived antibody responses may not always be a prerequisite for protection, and that antibody longevity varies in an exposure- and age-dependent manner.
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Affiliation(s)
- Lars Hviid
- Centre for Medical Parasitology at Institute for Medical Microbiology and Immunology, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
| | - Lea Barfod
- Centre for Medical Parasitology at Institute for Medical Microbiology and Immunology, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Freya J I Fowkes
- Macfarlane Burnet Institute of Medical Research, Melbourne, Victoria, Australia; Centre for Epidemiology and Biostatistics, University of Melbourne, Australia; Department of Epidemiology and Preventive Medicine and Department of Infectious Diseases, Monash University, Melbourne, Australia
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15
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Ampomah P, Stevenson L, Ofori MF, Barfod L, Hviid L. Kinetics of B cell responses to Plasmodium falciparum erythrocyte membrane protein 1 in Ghanaian women naturally exposed to malaria parasites. J Immunol 2014; 192:5236-44. [PMID: 24760153 DOI: 10.4049/jimmunol.1400325] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Naturally acquired protective immunity to Plasmodium falciparum malaria takes years to develop. It relies mainly on Abs, particularly IgG specific for Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) proteins on the infected erythrocyte surface. It is only partially understood why acquisition of clinical protection takes years to develop, but it probably involves a range of immune-evasive parasite features, not least of which are PfEMP1 polymorphism and clonal variation. Parasite-induced subversion of immunological memory and expansion of "atypical" memory B cells may also contribute. In this first, to our knowledge, longitudinal study of its kind, we measured B cell subset composition, as well as PfEMP1-specific Ab levels and memory B cell frequencies, in Ghanaian women followed from early pregnancy up to 1 y after delivery. Cell phenotypes and Ag-specific B cell function were assessed three times during and after pregnancy. Levels of IgG specific for pregnancy-restricted, VAR2CSA-type PfEMP1 increased markedly during pregnancy and declined after delivery, whereas IgG levels specific for two PfEMP1 proteins not restricted to pregnancy did not. Changes in VAR2CSA-specific memory B cell frequencies showed typical primary memory induction among primigravidae and recall expansion among multigravidae, followed by contraction postpartum in all. No systematic changes in the frequencies of memory B cells specific for the two other PfEMP1 proteins were identified. The B cell subset analysis confirmed earlier reports of high atypical memory B cell frequencies among residents of P. falciparum-endemic areas, and indicated an additional effect of pregnancy. Our study provides new knowledge regarding immunity to P. falciparum malaria and underpins efforts to develop PfEMP1-based vaccines against this disease.
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Affiliation(s)
- Paulina Ampomah
- Centre for Medical Parasitology, University of Copenhagen and Copenhagen University Hospital (Rigshospitalet), 2100 Copenhagen Ø, Denmark; and
| | - Liz Stevenson
- Centre for Medical Parasitology, University of Copenhagen and Copenhagen University Hospital (Rigshospitalet), 2100 Copenhagen Ø, Denmark; and
| | - Michael F Ofori
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Lea Barfod
- Centre for Medical Parasitology, University of Copenhagen and Copenhagen University Hospital (Rigshospitalet), 2100 Copenhagen Ø, Denmark; and
| | - Lars Hviid
- Centre for Medical Parasitology, University of Copenhagen and Copenhagen University Hospital (Rigshospitalet), 2100 Copenhagen Ø, Denmark; and
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Quadt KA, Barfod L, Andersen D, Bruun J, Gyan B, Hassenkam T, Ofori MF, Hviid L. The density of knobs on Plasmodium falciparum-infected erythrocytes depends on developmental age and varies among isolates. PLoS One 2012; 7:e45658. [PMID: 23029166 PMCID: PMC3447797 DOI: 10.1371/journal.pone.0045658] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 08/20/2012] [Indexed: 12/12/2022] Open
Abstract
Background The virulence of Plasmodium falciparum malaria is related to the parasite’s ability to evade host immunity through clonal antigenic variation and tissue-specific adhesion of infected erythrocytes (IEs). The P. falciparum erythrocyte membrane protein 1 (PfEMP1) family expressed on dome-shaped protrusions called knobs on the IE surface is central to both. Differences in receptor specificity and affinity of expressed PfEMP1 are important for IE adhesiveness, but it is not known whether differences in the number and size of the knobs on which the PfEMP1 proteins are expressed also play a role. Therefore, the aim of this study was to provide detailed information on isolate- and time-dependent differences in knob size and density. Methodology/Principal Findings We used atomic force microscopy to characterize knobs on the surface of P. falciparum-infected erythrocytes. Fourteen ex vivo isolates from Ghanaian children with malaria and 10 P. falciparum isolates selected in vitro for expression of a particular PfEMP1 protein (VAR2CSA) were examined. Knob density increased from ∼20 h to ∼35 h post-invasion, with significant variation among isolates. The knob density ex vivo, which was about five-fold higher than following long-term in vitro culture, started to decline within a few months of culture. Although knob diameter and height varied among isolates, we did not observe significant time-dependent variation in these dimensions. Conclusions/Significance The density of knobs on the P. falciparum-IE surface depends on time since invasion, but is also determined by the infecting isolate in a time-independent manner. This is the first study to quantitatively evaluate knob densities and dimensions on different P. falciparum isolates, to examine ex vivo isolates from humans, and to compare ex vivo and long-term in vitro-cultured isolates. Our findings contribute to the understanding of the interaction between P. falciparum parasites and the infected host.
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Affiliation(s)
- Katharina A. Quadt
- Centre for Medical Parasitology at i, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Lea Barfod
- Centre for Medical Parasitology at i, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Daniel Andersen
- Centre for Medical Parasitology at i, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Jonas Bruun
- Centre for Medical Parasitology at i, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Ben Gyan
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Tue Hassenkam
- Nano-Science Centre, Department of Chemistry, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Michael F. Ofori
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Lars Hviid
- Centre for Medical Parasitology at i, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
- * E-mail:
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Barfod L, Dobrilovic T, Magistrado P, Khunrae P, Viwami F, Bruun J, Dahlbäck M, Bernasconi NL, Fried M, John D, Duffy PE, Salanti A, Lanzavecchia A, Lim CT, Ndam NT, Higgins MK, Hviid L. Chondroitin sulfate A-adhering Plasmodium falciparum-infected erythrocytes express functionally important antibody epitopes shared by multiple variants. J Immunol 2010; 185:7553-61. [PMID: 21078904 DOI: 10.4049/jimmunol.1002390] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [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
Acquired protection from Plasmodium falciparum placental malaria, a major cause of maternal, fetal, and infant morbidity, is mediated by IgG specific for the P. falciparum erythrocyte membrane protein 1 variant VAR2CSA. This protein enables adhesion of P. falciparum-infected erythrocytes to chondroitin sulfate A in the intervillous space. Although interclonal variation of the var2csa gene is lower than that among var genes in general, VAR2CSA-specific Abs appear to target mainly polymorphic epitopes. This has raised doubts about the feasibility of VAR2CSA-based vaccines. We used eight human monoclonal IgG Abs from affinity-matured memory B cells of P. falciparum-exposed women to study interclonal variation and functional importance of Ab epitopes among placental and peripheral parasites from East and West Africa. Most placental P. falciparum isolates were labeled by several mAbs, whereas peripheral isolates from children were essentially nonreactive. The mAb reactivity of peripheral isolates from pregnant women indicated that some were placental, whereas others had alternative sequestration foci. Most of the mAbs were comparable in their reactivity with bound infected erythrocytes (IEs) and recombinant VAR2CSA and interfered with IE and/or VAR2CSA binding to chondroitin sulfate A. Pair-wise mAb combinations were more inhibitory than single mAbs, and all of the mAbs together was the most efficient combination. Each mAb could opsonize IEs for phagocytosis, and a combination of the eight mAbs caused phagocytosis similar to that of plasma IgG-opsonized IEs. We conclude that functionally important Ab epitopes are shared by the majority of polymorphic VAR2CSA variants, which supports the feasibility of VAR2CSA-based vaccines against placental malaria.
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Affiliation(s)
- Lea Barfod
- Centre for Medical Parasitology, Department of International Health, Immunology, and Microbiology, University of Copenhagen, Denmark
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18
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Joergensen LM, Salanti A, Dobrilovic T, Barfod L, Hassenkam T, Theander TG, Hviid L, Arnot DE. The kinetics of antibody binding to Plasmodium falciparum VAR2CSA PfEMP1 antigen and modelling of PfEMP1 antigen packing on the membrane knobs. Malar J 2010; 9:100. [PMID: 20403153 PMCID: PMC2868858 DOI: 10.1186/1475-2875-9-100] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [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: 12/22/2009] [Accepted: 04/19/2010] [Indexed: 11/25/2022] Open
Abstract
Background Infected humans make protective antibody responses to the PfEMP1 adhesion antigens exported by Plasmodium falciparum parasites to the erythrocyte membrane, but little is known about the kinetics of this antibody-receptor binding reaction or how the topology of PfEMP1 on the parasitized erythrocyte membrane influences antibody association with, and dissociation from, its antigenic target. Methods A Quartz Crystal Microbalance biosensor was used to measure the association and dissociation kinetics of VAR2CSA PfEMP1 binding to human monoclonal antibodies. Immuno-fluorescence microscopy was used to visualize antibody-mediated adhesion between the surfaces of live infected erythrocytes and atomic force microscopy was used to obtain higher resolution images of the membrane knobs on the infected erythrocyte to estimate knob surface areas and model VAR2CSA packing density on the knob. Results Kinetic analysis indicates that antibody dissociation from the VAR2CSA PfEMP1 antigen is extremely slow when there is a high avidity interaction. High avidity binding to PfEMP1 antigens on the surface of P. falciparum-infected erythrocytes in turn requires bivalent cross-linking of epitopes positioned within the distance that can be bridged by antibody. Calculations of the surface area of the knobs and the possible densities of PfEMP1 packing on the knobs indicate that high-avidity cross-linking antibody reactions are constrained by the architecture of the knobs and the large size of PfEMP1 molecules. Conclusions High avidity is required to achieve the strongest binding to VAR2CSA PfEMP1, but the structures that display PfEMP1 also tend to inhibit cross-linking between PfEMP1 antigens, by holding many binding epitopes at distances beyond the 15-18 nm sweep radius of an antibody. The large size of PfEMP1 will also constrain intra-knob cross-linking interactions. This analysis indicates that effective vaccines targeting the parasite's vulnerable adhesion receptors should primarily induce strongly adhering, high avidity antibodies whose association rate constant is less important than their dissociation rate constant.
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Affiliation(s)
- Lars M Joergensen
- Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health Sciences, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), CSS Øster Farimagsgade 5, Building 22 & 23, Postbox 2099, 1014 Copenhagen K, Denmark.
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Soerli J, Barfod L, Lavstsen T, Bernasconi NL, Lanzavecchia A, Hviid L. Human monoclonal IgG selection of Plasmodium falciparum for the expression of placental malaria-specific variant surface antigens. Parasite Immunol 2009; 31:341-6. [PMID: 19493213 PMCID: PMC3001033 DOI: 10.1111/j.1365-3024.2009.01097.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [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: 11/26/2022]
Abstract
Pregnancy-associatedPlasmodium falciparum malaria (PAM) is a major cause of morbidity and mortality in African women and their offspring. PAM is characterized by accumulation of infected erythrocytes (IEs) that adhere to chondroitin sulphate A (CSA) in the placental intervillous space. We show here that human monoclonal IgG antibodies with specificity for variant surface antigens (VSA) specifically expressed by CSA-adhering IEs (VSAPAM) can be used in vitro to select parasites from nonpregnant donors to express VSAPAM and that this selection for VSAPAM expression results in preferential transcription of var2csa. The results corroborate current efforts to develop PAM-specific vaccines based on VAR2CSA.
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Affiliation(s)
- J Soerli
- Centre for Medical Parasitology, Department of International Health, Immunology and Microbiology, University of Copenhagen Denmark
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Hviid L, Barfod L. Malaria vaccines: immunity, models and monoclonal antibodies. Trends Parasitol 2008; 24:392-5. [PMID: 18675589 DOI: 10.1016/j.pt.2008.05.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [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: 02/03/2008] [Revised: 04/10/2008] [Accepted: 05/20/2008] [Indexed: 11/17/2022]
Abstract
Although experts in the field have agreed on the malaria vaccine technology roadmap that should be followed (http://www.malariavaccineroadmap.net/), the path towards an effective malaria vaccine remains littered with intellectual and practical pot-holes. The animal models that are currently available are problematic, and current understanding of the exact mechanisms and targets of protective immune responses is incomplete. However, recent technological advances might help overcome some of these hurdles.
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Affiliation(s)
- Lars Hviid
- Centre for Medical Parasitology at the Department for International Health, Immunology, and Microbiology (ISIM), University of Copenhagen, 1014 Copenhagen K, Denmark.
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Barfod L, Bernasconi NL, Dahlbäck M, Jarrossay D, Andersen PH, Salanti A, Ofori MF, Turner L, Resende M, Nielsen MA, Theander TG, Sallusto F, Lanzavecchia A, Hviid L. Human pregnancy-associated malaria-specific B cells target polymorphic, conformational epitopes in VAR2CSA. Mol Microbiol 2006; 63:335-47. [PMID: 17176260 PMCID: PMC2779471 DOI: 10.1111/j.1365-2958.2006.05503.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Pregnancy-associated malaria (PAM) is caused by Plasmodium falciparum-infected erythrocytes (IEs) that bind to chondroitin sulphate A (CSA) in the placenta by PAM-associated clonally variant surface antigens (VSA). Pregnancy-specific VSA (VSAPAM), which include the PfEMP1 variant VAR2CSA, are targets of IgG-mediated protective immunity to PAM. Here, we report an investigation of the specificity of naturally acquired immunity to PAM, using eight human monoclonal IgG1 antibodies that react exclusively with intact CSA-adhering IEs expressing VSAPAM. Four reacted in Western blotting with high-molecular-weight (> 200 kDa) proteins, while seven reacted with either the DBL3-X or the DBL5-ε domains of VAR2CSA expressed either as Baculovirus constructs or on the surface of transfected Jurkat cells. We used a panel of recombinant antigens representing DBL3-X domains from P. falciparum field isolates to evaluate B-cell epitope diversity among parasite isolates, and identified the binding site of one monoclonal antibody using a chimeric DBL3-X construct. Our findings show that there is a high-frequency memory response to VSAPAM, indicating that VAR2CSA is a primary target of naturally acquired PAM-specific protective immunity, and demonstrate the value of human monoclonal antibodies and conformationally intact recombinant antigens in VSA characterization.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antibodies, Monoclonal/immunology
- Antigens, Protozoan/chemistry
- Antigens, Protozoan/immunology
- B-Lymphocytes/immunology
- Blotting, Western
- Cells, Cultured
- Enzyme-Linked Immunosorbent Assay
- Epitope Mapping
- Epitopes, B-Lymphocyte/immunology
- Female
- Flow Cytometry
- Humans
- Jurkat Cells
- Malaria, Falciparum/immunology
- Microscopy, Fluorescence
- Models, Molecular
- Molecular Sequence Data
- Plasmodium falciparum/immunology
- Pregnancy
- Pregnancy Complications, Parasitic/immunology
- Sequence Alignment
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Affiliation(s)
- Lea Barfod
- Centre for Medical Parasitology at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet) and Institute for Medical Microbiology and Immunology, University of CopenhagenCopenhagen, Denmark.
| | | | - Madeleine Dahlbäck
- Centre for Medical Parasitology at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet) and Institute for Medical Microbiology and Immunology, University of CopenhagenCopenhagen, Denmark.
| | - David Jarrossay
- Institute for Research in BiomedicineBellinzona, Switzerland.
| | - Pernille Haste Andersen
- Center for Biological Sequence Analysis, BioCentrum-DTU, Technical University of DenmarkLyngby, Denmark.
| | - Ali Salanti
- Centre for Medical Parasitology at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet) and Institute for Medical Microbiology and Immunology, University of CopenhagenCopenhagen, Denmark.
| | - Michael F Ofori
- Centre for Medical Parasitology at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet) and Institute for Medical Microbiology and Immunology, University of CopenhagenCopenhagen, Denmark.
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of GhanaLegon, Ghana.
| | - Louise Turner
- Centre for Medical Parasitology at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet) and Institute for Medical Microbiology and Immunology, University of CopenhagenCopenhagen, Denmark.
| | - Mafalda Resende
- Centre for Medical Parasitology at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet) and Institute for Medical Microbiology and Immunology, University of CopenhagenCopenhagen, Denmark.
| | - Morten A Nielsen
- Centre for Medical Parasitology at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet) and Institute for Medical Microbiology and Immunology, University of CopenhagenCopenhagen, Denmark.
| | - Thor G Theander
- Centre for Medical Parasitology at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet) and Institute for Medical Microbiology and Immunology, University of CopenhagenCopenhagen, Denmark.
| | | | - Antonio Lanzavecchia
- Institute for Research in BiomedicineBellinzona, Switzerland.
- **E-mail ; Tel. (+41) 91 82 00 310; Fax (+41) 91 82 00 312
| | - Lars Hviid
- Centre for Medical Parasitology at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet) and Institute for Medical Microbiology and Immunology, University of CopenhagenCopenhagen, Denmark.
- *For correspondence. E-mail ; Tel. (+45) 35 45 79 57; Fax (+45) 35 45 76 44
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Barfod L, Nielsen MA, Turner L, Dahlbäck M, Jensen ATR, Hviid L, Theander TG, Salanti A. Baculovirus-expressed constructs induce immunoglobulin G that recognizes VAR2CSA on Plasmodium falciparum-infected erythrocytes. Infect Immun 2006; 74:4357-60. [PMID: 16790811 PMCID: PMC1489712 DOI: 10.1128/iai.01617-05] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [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
We raised specific antisera against recombinant VAR2CSA domains produced in Escherichia coli and in insect cells. All were reactive in enzyme-linked immunosorbent assay, but only insect cell-derived constructs induced immunoglobulin G (IgG) that was reactive with native VAR2CSA on the surface of infected erythrocytes. Our data show that five of the six VAR2CSA Duffy-binding-like domains are surface exposed and that induction of surface-reactive VAR2CSA-specific IgG depends critically upon antigen conformation. These findings have implications for the development of vaccines against pregnancy-associated Plasmodium falciparum malaria.
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Affiliation(s)
- Lea Barfod
- Institute for Medical Microbiology and Immunology, Panum Institute 24-2, Blegdamsvej 3, 2200 Copenhagen N, Denmark
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Salanti A, Dahlbäck M, Turner L, Nielsen MA, Barfod L, Magistrado P, Jensen ATR, Lavstsen T, Ofori MF, Marsh K, Hviid L, Theander TG. Evidence for the involvement of VAR2CSA in pregnancy-associated malaria. ACTA ACUST UNITED AC 2005; 200:1197-203. [PMID: 15520249 PMCID: PMC2211857 DOI: 10.1084/jem.20041579] [Citation(s) in RCA: 443] [Impact Index Per Article: 23.3] [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] [Indexed: 11/16/2022]
Abstract
In Plasmodium falciparum–endemic areas, pregnancy-associated malaria (PAM) is an important health problem. The condition is precipitated by accumulation of parasite-infected erythrocytes (IEs) in the placenta, and this process is mediated by parasite-encoded variant surface antigens (VSA) binding to chondroitin sulfate A (CSA). Parasites causing PAM express unique VSA types, VSAPAM, which can be serologically classified as sex specific and parity dependent. It is sex specific because men from malaria-endemic areas do not develop VSAPAM antibodies; it is parity dependent because women acquire anti-VSAPAM immunoglobulin (Ig) G as a function of parity. Previously, it was shown that transcription of var2csa is up-regulated in placental parasites and parasites selected for CSA binding. Here, we show the following: (a) that VAR2CSA is expressed on the surface of CSA-selected IEs; (b) that VAR2CSA is recognized by endemic plasma in a sex-specific and parity-dependent manner; (c) that high anti-VAR2CSA IgG levels can be found in pregnant women from both West and East Africa; and (d) that women with high plasma levels of anti-VAR2CSA IgG give birth to markedly heavier babies and have a much lower risk of delivering low birth weight children than women with low levels.
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Affiliation(s)
- Ali Salanti
- Centre for Medical Parasitology, Dept. of Medical Microbiology and Immunology, Panum Institute 24-2, Blegdamsvej 3, 2200 Copenhagen, Denmark.
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Abstract
Licochalcone A (LicA), an oxygenated chalcone, has been shown to inhibit the growth of both parasites and bacteria. In this study, we investigated the effect of LicA and four synthetic analogues on the activity of human peripheral blood mononuclear cell proliferation and cytokine production. Four out of five chalcones tested inhibited the proliferation of lymphocytes measured by thymidine incorporation and by flow cytometry. The production of pro- and anti-inflammatory cytokines from monocytes and T cells was also inhibited by four of five chalcones. Furthermore, intracellular detection of cytokines revealed that the chalcones inhibited the production rather than the release of the cytokines. Taken together, these results indicate that LicA and some analogues may have immunomodulatory effects, and may thus be candidates not only as anti-microbial agents, but also for the treatment of other types of diseases.
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Affiliation(s)
- Lea Barfod
- Department of Clinical Microbiology, Centre for Medical Parasitology, Copenhagen University Hospital (Rigshospitalet), Denmark
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