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Gill J, Sharma A. Structural and genomic analysis of single nucleotide polymorphisms in human host factor endothelial protein C receptor (EPCR) reveals complex interplay with malaria parasites. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2023; 110:105413. [PMID: 36775045 DOI: 10.1016/j.meegid.2023.105413] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 01/12/2023] [Accepted: 02/08/2023] [Indexed: 02/12/2023]
Abstract
Plasmodium parasites responsible for malaria follow a complex life cycle of which half takes place inside the human host. Parasites present diverse antigens at different stages of their life cycle and interact with many surface molecules to attach to and enter host cells. The CIDRα1 domain of Plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1) in infected erythrocytes adheres to one such vascular receptor endothelial protein C receptor (EPCR). EPCR is implicated in the pathogenesis of severe malaria as preferential binding of CIDRα1 to endothelium results in widespread sequestration of infected erythrocytes leading to endothelium inflammation and severe disease. A single EPCR variant S219G is clinically reported to provide protection from severe malaria. In this work, we have collated all single nucleotide polymorphisms (SNPs) in EPCR from dbSNP. We structurally mapped the SNPs on the three-dimensional complex of EPCR and PfEMP1 CIDRα1. Analysis shows that most EPCR mutations lie on the receptor surface and are non-conservative. Of the 11 mutations in the CIDRα1-interaction region of EPCR, S88P, L96V/I, and R98L/H/P/C are seen with comparably higher occurrences in diverse populations. Our structural analysis details a framework of the interactions between the parasite ligand and host factor EPCR. These structural glimpses provide a blueprint for designing both field-based variant sequencing studies and vaccine development.
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Affiliation(s)
- Jasmita Gill
- ICMR-National Institute of Malaria Research, New Delhi, India.
| | - Amit Sharma
- ICMR-National Institute of Malaria Research, New Delhi, India; International Centre for Genetic Engineering and Biotechnology, New Delhi, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India.
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2
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CD36-A Host Receptor Necessary for Malaria Parasites to Establish and Maintain Infection. Microorganisms 2022; 10:microorganisms10122356. [PMID: 36557610 PMCID: PMC9785914 DOI: 10.3390/microorganisms10122356] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 11/21/2022] [Accepted: 11/27/2022] [Indexed: 11/30/2022] Open
Abstract
Plasmodium falciparum-infected erythrocytes (PfIEs) present P. falciparum erythrocyte membrane protein 1 proteins (PfEMP1s) on the cell surface, via which they cytoadhere to various endothelial cell receptors (ECRs) on the walls of human blood vessels. This prevents the parasite from passing through the spleen, which would lead to its elimination. Each P. falciparum isolate has about 60 different PfEMP1s acting as ligands, and at least 24 ECRs have been identified as interaction partners. Interestingly, in every parasite genome sequenced to date, at least 75% of the encoded PfEMP1s have a binding domain for the scavenger receptor CD36 widely distributed on host endothelial cells and many other cell types. Here, we discuss why the interaction between PfIEs and CD36 is optimal to maintain a finely regulated equilibrium that allows the parasite to multiply and spread while causing minimal harm to the host in most infections.
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Bourgouin C, Puchot N, Paul R. [To stick or not to stick: A Plasmodium falciparum adaptive strategy to persist during the dry season]. Med Sci (Paris) 2022; 38:9-12. [PMID: 35060875 DOI: 10.1051/medsci/2021230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Catherine Bourgouin
- Unité de Génétique fonctionnelle des maladies infectieuses, Institut Pasteur, CNRS UMR 2000, 75015 Paris, France
| | - Nicolas Puchot
- Unité de Génétique fonctionnelle des maladies infectieuses, Institut Pasteur, CNRS UMR 2000, 75015 Paris, France
| | - Richard Paul
- Unité de Génétique fonctionnelle des maladies infectieuses, Institut Pasteur, CNRS UMR 2000, 75015 Paris, France
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Guillochon E, Fraering J, Joste V, Kamaliddin C, Vianou B, Houzé L, Baudrin LG, Faucher JF, Aubouy A, Houzé S, Cot M, Argy N, Taboureau O, Bertin GI. OUP accepted manuscript. J Infect Dis 2022; 225:2187-2196. [PMID: 35255125 PMCID: PMC9200161 DOI: 10.1093/infdis/jiac086] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 03/03/2022] [Indexed: 11/24/2022] Open
Abstract
Cerebral malaria (CM) is the severest form of Plasmodium falciparum infection. Children under 5 years old are those most vulnerable to CM, and they consequently have the highest risk of malaria-related death. Parasite-associated factors leading to CM are not yet fully elucidated. We therefore sought to characterize the gene expression profile associated with CM, using RNA sequencing data from 15 CM and 15 uncomplicated malaria isolates from Benin. Cerebral malaria parasites displayed reduced circulation times, possibly related to higher cytoadherence capacity. Consistent with the latter, we detected increased var genes abundance in CM isolates. Differential expression analyses showed that distinct transcriptome profiles are signatures of malaria severity. Genes involved in adhesion, excluding variant surface antigens, were dysregulated, supporting the idea of increased cytoadhesion capacity of CM parasites. Finally, we found dysregulated expression of genes in the entry into host pathway that may reflect greater erythrocyte invasion capacity of CM parasites.
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Affiliation(s)
- E Guillochon
- Université Paris Cité, MERIT, IRD, Paris, France
- Université Paris Cité, INSERM U1133, CNRS UMR 8251, Paris, France
| | - J Fraering
- Université Paris Cité, MERIT, IRD, Paris, France
| | - V Joste
- Université Paris Cité, MERIT, IRD, Paris, France
- Parasitology Laboratory, Hôpital Bichat - Claude-Bernard, APHP, Paris, France
- French Malaria Reference Center, Hôpital Bichat, APHP, Paris, France
| | - C Kamaliddin
- Cumming School of Medicine, The University of Calgary, Calgary, Alberta, Canada
| | - B Vianou
- Université Paris Cité, MERIT, IRD, Paris, France
- Institut de Recherche Clinique du Bénin, Cotonou, Bénin
| | - L Houzé
- Université Paris Cité, MERIT, IRD, Paris, France
| | - L G Baudrin
- Institut Curie Genomics of Excellence Platform, PSL Research University, Research Center, Institut Curie, Paris, France
| | - J F Faucher
- INSERM, Univ. Limoges, CHU Limoges, IRD, U1094 Tropical Neuroepidemiology, Institute of Epidemiology and Tropical Neurology, GEIST, Limoges, France
| | - A Aubouy
- Université de Toulouse, PHARMADEV, IRD, UPS, Toulouse, France
| | - S Houzé
- Université Paris Cité, MERIT, IRD, Paris, France
- Parasitology Laboratory, Hôpital Bichat - Claude-Bernard, APHP, Paris, France
- French Malaria Reference Center, Hôpital Bichat, APHP, Paris, France
| | - M Cot
- Université Paris Cité, MERIT, IRD, Paris, France
| | - N Argy
- Université Paris Cité, MERIT, IRD, Paris, France
- Parasitology Laboratory, Hôpital Bichat - Claude-Bernard, APHP, Paris, France
- French Malaria Reference Center, Hôpital Bichat, APHP, Paris, France
| | - O Taboureau
- Université Paris Cité, INSERM U1133, CNRS UMR 8251, Paris, France
| | - G I Bertin
- Correspondence: Gwladys I. Bertin, PhD, Université Paris Cité, MERIT, IRD, 4 avenue de l’Observatoire, 75006 Paris, France ()
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Wichers JS, Tonkin-Hill G, Thye T, Krumkamp R, Kreuels B, Strauss J, von Thien H, Scholz JAM, Smedegaard Hansson H, Weisel Jensen R, Turner L, Lorenz FR, Schöllhorn A, Bruchhaus I, Tannich E, Fendel R, Otto TD, Lavstsen T, Gilberger TW, Duffy MF, Bachmann A. Common virulence gene expression in adult first-time infected malaria patients and severe cases. eLife 2021; 10:e69040. [PMID: 33908865 PMCID: PMC8102065 DOI: 10.7554/elife.69040] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 04/18/2021] [Indexed: 12/22/2022] Open
Abstract
Sequestration of Plasmodium falciparum(P. falciparum)-infected erythrocytes to host endothelium through the parasite-derived P. falciparum erythrocyte membrane protein 1 (PfEMP1) adhesion proteins is central to the development of malaria pathogenesis. PfEMP1 proteins have diversified and expanded to encompass many sequence variants, conferring each parasite a similar array of human endothelial receptor-binding phenotypes. Here, we analyzed RNA-seq profiles of parasites isolated from 32 P. falciparum-infected adult travellers returning to Germany. Patients were categorized into either malaria naive (n = 15) or pre-exposed (n = 17), and into severe (n = 8) or non-severe (n = 24) cases. For differential expression analysis, PfEMP1-encoding var gene transcripts were de novo assembled from RNA-seq data and, in parallel, var-expressed sequence tags were analyzed and used to predict the encoded domain composition of the transcripts. Both approaches showed in concordance that severe malaria was associated with PfEMP1 containing the endothelial protein C receptor (EPCR)-binding CIDRα1 domain, whereas CD36-binding PfEMP1 was linked to non-severe malaria outcomes. First-time infected adults were more likely to develop severe symptoms and tended to be infected for a longer period. Thus, parasites with more pathogenic PfEMP1 variants are more common in patients with a naive immune status, and/or adverse inflammatory host responses to first infections favor the growth of EPCR-binding parasites.
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Affiliation(s)
- J Stephan Wichers
- Molecular Biology and Immunology, Bernhard Nocht Institute for Tropical MedicineHamburgGermany
- Centre for Structural Systems BiologyHamburgGermany
- Biology Department, University of HamburgHamburgGermany
| | | | - Thorsten Thye
- Epidemiology and Diagnostics, Bernhard Nocht Institute for Tropical MedicineHamburgGermany
| | - Ralf Krumkamp
- Epidemiology and Diagnostics, Bernhard Nocht Institute for Tropical MedicineHamburgGermany
- German Center for Infection Research (DZIF), Partner Site Hamburg-Lübeck-Borstel-RiemsHamburgGermany
| | - Benno Kreuels
- Department of Tropical Medicine, Bernhard Nocht Institute for Tropical Medicine, GermanyHamburgGermany
- Department of Medicine, College of MedicineBlantyreMalawi
- Department of Medicine, University Medical Center Hamburg-EppendorfHamburgGermany
| | - Jan Strauss
- Molecular Biology and Immunology, Bernhard Nocht Institute for Tropical MedicineHamburgGermany
- Centre for Structural Systems BiologyHamburgGermany
- Biology Department, University of HamburgHamburgGermany
| | - Heidrun von Thien
- Molecular Biology and Immunology, Bernhard Nocht Institute for Tropical MedicineHamburgGermany
- Centre for Structural Systems BiologyHamburgGermany
- Biology Department, University of HamburgHamburgGermany
| | - Judith AM Scholz
- Molecular Biology and Immunology, Bernhard Nocht Institute for Tropical MedicineHamburgGermany
| | | | | | | | | | - Anna Schöllhorn
- Institute of Tropical Medicine, University of TübingenTübingenGermany
| | - Iris Bruchhaus
- Molecular Biology and Immunology, Bernhard Nocht Institute for Tropical MedicineHamburgGermany
- Biology Department, University of HamburgHamburgGermany
| | - Egbert Tannich
- Epidemiology and Diagnostics, Bernhard Nocht Institute for Tropical MedicineHamburgGermany
- German Center for Infection Research (DZIF), Partner Site Hamburg-Lübeck-Borstel-RiemsHamburgGermany
| | - Rolf Fendel
- Institute of Tropical Medicine, University of TübingenTübingenGermany
- German Center for Infection Research (DZIF), Partner Site TübingenTübingenGermany
| | - Thomas D Otto
- Institute of Infection, Immunity and Inflammation, University of GlasgowGlasgowUnited Kingdom
| | | | - Tim W Gilberger
- Molecular Biology and Immunology, Bernhard Nocht Institute for Tropical MedicineHamburgGermany
- Centre for Structural Systems BiologyHamburgGermany
- Biology Department, University of HamburgHamburgGermany
| | - Michael F Duffy
- Department of Microbiology and Immunology, University of MelbourneMelbourneAustralia
| | - Anna Bachmann
- Molecular Biology and Immunology, Bernhard Nocht Institute for Tropical MedicineHamburgGermany
- Centre for Structural Systems BiologyHamburgGermany
- Biology Department, University of HamburgHamburgGermany
- German Center for Infection Research (DZIF), Partner Site Hamburg-Lübeck-Borstel-RiemsHamburgGermany
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Structure-Guided Design of a Synthetic Mimic of an Endothelial Protein C Receptor-Binding PfEMP1 Protein. mSphere 2021; 6:6/1/e01081-20. [PMID: 33408232 PMCID: PMC7845591 DOI: 10.1128/msphere.01081-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vaccines train our immune systems to generate antibodies which recognize pathogens. Some of these antibodies are highly protective, preventing infection, while others are ineffective. Structure-guided vaccine design provides a route to elicit a focused immune response against the most functionally important regions of a pathogen surface. This can be achieved by identifying epitopes for neutralizing antibodies through structural methods and recapitulating these epitopes by grafting their core structural features onto smaller scaffolds. In this study, we conducted a modified version of this protocol. We focused on the PfEMP1 protein family found on the surfaces of erythrocytes infected with Plasmodium falciparum. A subset of PfEMP1 proteins bind to endothelial protein C receptor (EPCR), and their expression correlates with development of the symptoms of severe malaria. Structural studies revealed that PfEMP1 molecules present a helix-kinked-helix motif that forms the core of the EPCR-binding site. Using Rosetta-based design, we successfully grafted this motif onto a three-helical bundle scaffold. We show that this synthetic binder interacts with EPCR with nanomolar affinity and adopts the expected structure. We also assessed its ability to bind to antibodies found in immunized animals and in humans from malaria-endemic regions. Finally, we tested the capacity of the synthetic binder to effectively elicit antibodies that prevent EPCR binding and analyzed the degree of cross-reactivity of these antibodies across a diverse repertoire of EPCR-binding PfEMP1 proteins. Despite our synthetic binder adopting the correct structure, we find that it is not as effective as the CIDRα domain on which it is based for inducing adhesion-inhibitory antibodies. This cautions against the rational design of focused immunogens that contain the core features of a ligand-binding site of a protein family, rather than those of a neutralizing antibody epitope. IMPORTANCE Vaccines train our immune systems to generate antibodies which recognize pathogens. Some of these antibodies are highly protective, preventing infection, while others are ineffective. Structure-guided rational approaches allow design of synthetic molecules which contain only the regions of a pathogen required to induce production of protective antibodies. On the surfaces of red blood cells infected by the malaria parasite Plasmodium falciparum are parasite molecules called PfEMP1 proteins. PfEMP1 proteins, which bind to human receptor EPCR, are linked to development of severe malaria. We have designed a synthetic protein on which we grafted the EPCR-binding surface of a PfEMP1 protein. We use this molecule to show which fraction of protective antibodies recognize the EPCR-binding surface and test its effectiveness as a vaccine immunogen.
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Wichers JS, Scholz JAM, Strauss J, Witt S, Lill A, Ehnold LI, Neupert N, Liffner B, Lühken R, Petter M, Lorenzen S, Wilson DW, Löw C, Lavazec C, Bruchhaus I, Tannich E, Gilberger TW, Bachmann A. Dissecting the Gene Expression, Localization, Membrane Topology, and Function of the Plasmodium falciparum STEVOR Protein Family. mBio 2019; 10:e01500-19. [PMID: 31363031 PMCID: PMC6667621 DOI: 10.1128/mbio.01500-19] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 07/02/2019] [Indexed: 01/22/2023] Open
Abstract
During its intraerythrocytic development, the malaria parasite Plasmodium falciparum exposes variant surface antigens (VSAs) on infected erythrocytes to establish and maintain an infection. One family of small VSAs is the polymorphic STEVOR proteins, which are marked for export to the host cell surface through their PEXEL signal peptide. Interestingly, some STEVORs have also been reported to localize to the parasite plasma membrane and apical organelles, pointing toward a putative function in host cell egress or invasion. Using deep RNA sequencing analysis, we characterized P. falciparumstevor gene expression across the intraerythrocytic development cycle, including free merozoites, in detail and used the resulting stevor expression profiles for hierarchical clustering. We found that most stevor genes show biphasic expression oscillation, with maximum expression during trophozoite stages and a second peak in late schizonts. We selected four STEVOR variants, confirmed the expected export of these proteins to the host cell membrane, and tracked them to a secondary location, either to the parasite plasma membrane or the secretory organelles of merozoites in late schizont stages. We investigated the function of a particular STEVOR that showed rhoptry localization and demonstrated its role at the parasite-host interface during host cell invasion by specific antisera and targeted gene disruption. Experimentally determined membrane topology of this STEVOR revealed a single transmembrane domain exposing the semiconserved as well as variable protein regions to the cell surface.IMPORTANCE Malaria claims about half a million lives each year. Plasmodium falciparum, the causative agent of the most severe form of the disease, uses proteins that are translocated to the surface of infected erythrocytes for immune evasion. To circumvent the detection of these gene products by the immune system, the parasite evolved a complex strategy that includes gene duplications and elaborate sequence polymorphism. STEVORs are one family of these variant surface antigens and are encoded by about 40 genes. Using deep RNA sequencing of blood-stage parasites, including free merozoites, we first established stevor expression of the cultured isolate and compared it with published transcriptomes. We reveal a biphasic expression of most stevor genes and confirm this for individual STEVORs at the protein level. The membrane topology of a rhoptry-associated variant was experimentally elucidated and linked to host cell invasion, underlining the importance of this multifunctional protein family for parasite proliferation.
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Affiliation(s)
- J Stephan Wichers
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- Centre for Structural Systems Biology, Hamburg, Germany
| | | | - Jan Strauss
- Centre for Structural Systems Biology (CSSB), DESY, and European Molecular Biology Laboratory Hamburg, Hamburg, Germany
| | - Susanne Witt
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Andrés Lill
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- Centre for Structural Systems Biology, Hamburg, Germany
| | | | | | - Benjamin Liffner
- Research Centre for Infectious Diseases, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | - Renke Lühken
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Michaela Petter
- Institute of Microbiology, University Hospital Erlangen, Erlangen, Germany
| | - Stephan Lorenzen
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Danny W Wilson
- Research Centre for Infectious Diseases, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
- Burnet Institute, Melbourne, Victoria, Australia
| | - Christian Löw
- Centre for Structural Systems Biology (CSSB), DESY, and European Molecular Biology Laboratory Hamburg, Hamburg, Germany
| | | | - Iris Bruchhaus
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Egbert Tannich
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Tim W Gilberger
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- Centre for Structural Systems Biology, Hamburg, Germany
- Biology Department, University of Hamburg, Hamburg, Germany
| | - Anna Bachmann
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- Centre for Structural Systems Biology, Hamburg, Germany
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8
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Bachmann A, Bruske E, Krumkamp R, Turner L, Wichers JS, Petter M, Held J, Duffy MF, Sim BKL, Hoffman SL, Kremsner PG, Lell B, Lavstsen T, Frank M, Mordmüller B, Tannich E. Controlled human malaria infection with Plasmodium falciparum demonstrates impact of naturally acquired immunity on virulence gene expression. PLoS Pathog 2019; 15:e1007906. [PMID: 31295334 PMCID: PMC6650087 DOI: 10.1371/journal.ppat.1007906] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 07/23/2019] [Accepted: 06/10/2019] [Indexed: 12/14/2022] Open
Abstract
The pathogenesis of Plasmodium falciparum malaria is linked to the variant surface antigen PfEMP1, which mediates tethering of infected erythrocytes to the host endothelium and is encoded by approximately 60 var genes per parasite genome. Repeated episodes of malaria infection result in the gradual acquisition of protective antibodies against PfEMP1 variants. The antibody repertoire is believed to provide a selective pressure driving the clonal expansion of parasites expressing unrecognized PfEMP1 variants, however, due to the lack of experimental in vivo models there is only limited experimental evidence in support of this concept. To get insight into the impact of naturally acquired immunity on the expressed var gene repertoire early during infection we performed controlled human malaria infections of 20 adult African volunteers with life-long malaria exposure using aseptic, purified, cryopreserved P. falciparum sporozoites (Sanaria PfSPZ Challenge) and correlated serological data with var gene expression patterns from ex vivo parasites. Among the 10 African volunteers who developed patent infections, individuals with low antibody levels showed a steep rise in parasitemia accompanied by broad activation of multiple, predominantly subtelomeric var genes, similar to what we previously observed in naïve volunteers. In contrast, individuals with intermediate antibody levels developed asymptomatic infections and the ex vivo parasite populations expressed only few var gene variants, indicative of clonal selection. Importantly, in contrast to parasites from naïve volunteers, expression of var genes coding for endothelial protein C receptor (EPCR)-binding PfEMP1 that are associated with severe childhood malaria was rarely detected in semi-immune adult African volunteers. Moreover, we followed var gene expression for up to six parasite replication cycles and demonstrated for the first time in vivo a shift in the dominant var gene variant. In conclusion, our data suggest that P. falciparum activates multiple subtelomeric var genes at the onset of blood stage infection facilitating rapid expansion of parasite clones which express PfEMP1 variants unrecognized by the host's immune system, thus promoting overall parasite survival in the face of host immunity.
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Affiliation(s)
- Anna Bachmann
- Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- German Center for Infection Research (DZIF), partner site Hamburg-Borstel-Lübeck-Riems, Germany
| | - Ellen Bruske
- Institute of Tropical Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Ralf Krumkamp
- German Center for Infection Research (DZIF), partner site Hamburg-Borstel-Lübeck-Riems, Germany
- Infectious Disease Epidemiology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Louise Turner
- Centre for Medical Parasitology, University of Copenhagen, Copenhagen K, Denmark
| | - J. Stephan Wichers
- Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Michaela Petter
- Mikrobiologisches Institut–Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany
- School of BioSciences, Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Jana Held
- Institute of Tropical Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Michael F. Duffy
- School of BioSciences, Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
| | | | | | - Peter G. Kremsner
- Institute of Tropical Medicine, University Hospital Tübingen, Tübingen, Germany
- German Center for Infection Research (DZIF), partner site Tübingen, Germany
| | - Bertrand Lell
- Institute of Tropical Medicine, University Hospital Tübingen, Tübingen, Germany
- Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon
- German Center for Infection Research (DZIF), African partner institution, CERMEL, Gabon
| | - Thomas Lavstsen
- Centre for Medical Parasitology, University of Copenhagen, Copenhagen K, Denmark
| | - Matthias Frank
- Institute of Tropical Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Benjamin Mordmüller
- Institute of Tropical Medicine, University Hospital Tübingen, Tübingen, Germany
- German Center for Infection Research (DZIF), partner site Tübingen, Germany
| | - Egbert Tannich
- Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- German Center for Infection Research (DZIF), partner site Hamburg-Borstel-Lübeck-Riems, Germany
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Yam XY, Preiser PR. Host immune evasion strategies of malaria blood stage parasite. MOLECULAR BIOSYSTEMS 2018; 13:2498-2508. [PMID: 29091093 DOI: 10.1039/c7mb00502d] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Host immune evasion is a key strategy for the continual survival of many microbial pathogens including Apicomplexan protozoan: Plasmodium spp., the causative agent of Malaria. The malaria parasite has evolved a variety of mechanisms to evade the host immune responses within its two hosts: the female Anopheles mosquito vector and vertebrate host. In this review, we will focus on the molecular mechanisms of the immune evasion strategies used by the Plasmodium parasite at the blood stage which is responsible for the clinical manifestations of human malaria. We also aim to provide some insights on the potential targets for malaria interventions through the recent advancement in understanding the molecular biology of the parasite.
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Affiliation(s)
- Xue Yan Yam
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore.
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10
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Immunological bases of increased susceptibility to invasive nontyphoidal Salmonella infection in children with malaria and anaemia. Microbes Infect 2017; 20:589-598. [PMID: 29248635 PMCID: PMC6250906 DOI: 10.1016/j.micinf.2017.11.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 11/17/2017] [Accepted: 11/20/2017] [Indexed: 01/01/2023]
Abstract
Malaria and anaemia are key underlying factors for iNTS disease in African children. Knowledge of clinical and epidemiological risk-factors for iNTS disease has not been paralleled by an in-depth knowledge of the immunobiology of the disease. Herein, we review human and animal studies on mechanisms of increased susceptibility to iNTS in children.
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11
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Eichenberger RM, Ramakrishnan C, Russo G, Deplazes P, Hehl AB. Genome-wide analysis of gene expression and protein secretion of Babesia canis during virulent infection identifies potential pathogenicity factors. Sci Rep 2017; 7:3357. [PMID: 28611446 PMCID: PMC5469757 DOI: 10.1038/s41598-017-03445-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 04/27/2017] [Indexed: 12/14/2022] Open
Abstract
Infections of dogs with virulent strains of Babesia canis are characterized by rapid onset and high mortality, comparable to complicated human malaria. As in other apicomplexan parasites, most Babesia virulence factors responsible for survival and pathogenicity are secreted to the host cell surface and beyond where they remodel and biochemically modify the infected cell interacting with host proteins in a very specific manner. Here, we investigated factors secreted by B. canis during acute infections in dogs and report on in silico predictions and experimental analysis of the parasite’s exportome. As a backdrop, we generated a fully annotated B. canis genome sequence of a virulent Hungarian field isolate (strain BcH-CHIPZ) underpinned by extensive genome-wide RNA-seq analysis. We find evidence for conserved factors in apicomplexan hemoparasites involved in immune-evasion (e.g. VESA-protein family), proteins secreted across the iRBC membrane into the host bloodstream (e.g. SA- and Bc28 protein families), potential moonlighting proteins (e.g. profilin and histones), and uncharacterized antigens present during acute crisis in dogs. The combined data provides a first predicted and partially validated set of potential virulence factors exported during fatal infections, which can be exploited for urgently needed innovative intervention strategies aimed at facilitating diagnosis and management of canine babesiosis.
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Affiliation(s)
| | | | | | - Peter Deplazes
- Institute of Parasitology, University of Zurich, Zurich, Switzerland
| | - Adrian B Hehl
- Institute of Parasitology, University of Zurich, Zurich, Switzerland.
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12
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Fougère A, Jackson AP, Paraskevi Bechtsi D, Braks JAM, Annoura T, Fonager J, Spaccapelo R, Ramesar J, Chevalley-Maurel S, Klop O, van der Laan AMA, Tanke HJ, Kocken CHM, Pasini EM, Khan SM, Böhme U, van Ooij C, Otto TD, Janse CJ, Franke-Fayard B. Variant Exported Blood-Stage Proteins Encoded by Plasmodium Multigene Families Are Expressed in Liver Stages Where They Are Exported into the Parasitophorous Vacuole. PLoS Pathog 2016; 12:e1005917. [PMID: 27851824 PMCID: PMC5113031 DOI: 10.1371/journal.ppat.1005917] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 09/06/2016] [Indexed: 01/05/2023] Open
Abstract
Many variant proteins encoded by Plasmodium-specific multigene families are exported into red blood cells (RBC). P. falciparum-specific variant proteins encoded by the var, stevor and rifin multigene families are exported onto the surface of infected red blood cells (iRBC) and mediate interactions between iRBC and host cells resulting in tissue sequestration and rosetting. However, the precise function of most other Plasmodium multigene families encoding exported proteins is unknown. To understand the role of RBC-exported proteins of rodent malaria parasites (RMP) we analysed the expression and cellular location by fluorescent-tagging of members of the pir, fam-a and fam-b multigene families. Furthermore, we performed phylogenetic analyses of the fam-a and fam-b multigene families, which indicate that both families have a history of functional differentiation unique to RMP. We demonstrate for all three families that expression of family members in iRBC is not mutually exclusive. Most tagged proteins were transported into the iRBC cytoplasm but not onto the iRBC plasma membrane, indicating that they are unlikely to play a direct role in iRBC-host cell interactions. Unexpectedly, most family members are also expressed during the liver stage, where they are transported into the parasitophorous vacuole. This suggests that these protein families promote parasite development in both the liver and blood, either by supporting parasite development within hepatocytes and erythrocytes and/or by manipulating the host immune response. Indeed, in the case of Fam-A, which have a steroidogenic acute regulatory-related lipid transfer (START) domain, we found that several family members can transfer phosphatidylcholine in vitro. These observations indicate that these proteins may transport (host) phosphatidylcholine for membrane synthesis. This is the first demonstration of a biological function of any exported variant protein family of rodent malaria parasites. Malaria-parasites invade and multiply in hepatocytes and erythrocytes. The human parasite P. falciparum transports proteins encoded by multigene families onto the surface of erythrocytes, mediating interactions between infected red blood cells (iRBCs) and other host-cells and are thought to play a key role in parasite survival during blood-stage development. The function of other exported Plasmodium protein families remains largely unknown. We provide novel insights into expression and cellular location of proteins encoded by three large multigene families of rodent malaria parasites (Fam-a, Fam-b and PIR). Multiple members of the same family are expressed in a single iRBC, unlike P. falciparum PfEMP1 proteins where individual iRBCs express only a single member. Most proteins we examined are located in the RBC cytoplasm and are not transported onto the iRBC surface membrane, indicating that these proteins are unlikely to mediate interactions between iRBCs and host-cells. Unexpectedly, liver stages also express many of these proteins, where they locate to the vacuole surrounding the parasite inside the hepatocyte. In support of a role of these proteins for parasite growth within their host cells we provide evidence that Fam-A proteins have a role in uptake and transport of (host) phosphatidylcholine for parasite-membrane synthesis.
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Affiliation(s)
- Aurélie Fougère
- Leiden Malaria Research Group, Parasitology, Center of infectious Diseases, Leiden University Medical Center (LUMC), Leiden, The Netherlands
- Department of Experimental Medicine, University of Perugia, Italy
| | - Andrew P. Jackson
- Department of Infection Biology, Institute of Infection and Global Health, University of Liverpool, Liverpool, UnitedKingdom
| | | | - Joanna A. M. Braks
- Leiden Malaria Research Group, Parasitology, Center of infectious Diseases, Leiden University Medical Center (LUMC), Leiden, The Netherlands
| | - Takeshi Annoura
- Leiden Malaria Research Group, Parasitology, Center of infectious Diseases, Leiden University Medical Center (LUMC), Leiden, The Netherlands
- Department of Department of Parasitology, National Institute of Infectious Diseases (NIID), Tokyo, Japan
| | - Jannik Fonager
- Leiden Malaria Research Group, Parasitology, Center of infectious Diseases, Leiden University Medical Center (LUMC), Leiden, The Netherlands
- Department of Microbiological Diagnostics and Virology, Statens Serum Institute, Copenhagen, Denmark
| | | | - Jai Ramesar
- Leiden Malaria Research Group, Parasitology, Center of infectious Diseases, Leiden University Medical Center (LUMC), Leiden, The Netherlands
| | - Séverine Chevalley-Maurel
- Leiden Malaria Research Group, Parasitology, Center of infectious Diseases, Leiden University Medical Center (LUMC), Leiden, The Netherlands
| | - Onny Klop
- Leiden Malaria Research Group, Parasitology, Center of infectious Diseases, Leiden University Medical Center (LUMC), Leiden, The Netherlands
- Biomedical Primate Research Centre (BPRC), Rijswijk, The Netherlands
| | | | - Hans J. Tanke
- Department of Molecular Cell Biology, Leiden University Medical Center (LUMC), Leiden, The Netherlands
| | | | - Erica M. Pasini
- Biomedical Primate Research Centre (BPRC), Rijswijk, The Netherlands
| | - Shahid M. Khan
- Leiden Malaria Research Group, Parasitology, Center of infectious Diseases, Leiden University Medical Center (LUMC), Leiden, The Netherlands
| | - Ulrike Böhme
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, UnitedKingdom
| | - Christiaan van Ooij
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London, UnitedKingdom
| | - Thomas D. Otto
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, UnitedKingdom
| | - Chris J. Janse
- Leiden Malaria Research Group, Parasitology, Center of infectious Diseases, Leiden University Medical Center (LUMC), Leiden, The Netherlands
| | - Blandine Franke-Fayard
- Leiden Malaria Research Group, Parasitology, Center of infectious Diseases, Leiden University Medical Center (LUMC), Leiden, The Netherlands
- * E-mail:
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13
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Abstract
The Plasmodium falciparum erythrocyte membrane protein 1 antigens that are inserted onto the surface of P. falciparum infected erythrocytes play a key role both in the pathology of severe malaria and as targets of naturally acquired immunity. They might be considered unlikely vaccine targets because they are extremely diverse. However, several lines of evidence suggest that underneath this molecular diversity there are a restricted set of epitopes which may act as effective targets for a vaccine against severe malaria. Here we review some of the recent developments in this area of research, focusing on work that has assessed the potential of these molecules as possible vaccine targets.
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14
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Niang M, Bei AK, Madnani KG, Pelly S, Dankwa S, Kanjee U, Gunalan K, Amaladoss A, Yeo KP, Bob NS, Malleret B, Duraisingh MT, Preiser PR. STEVOR is a Plasmodium falciparum erythrocyte binding protein that mediates merozoite invasion and rosetting. Cell Host Microbe 2015; 16:81-93. [PMID: 25011110 DOI: 10.1016/j.chom.2014.06.004] [Citation(s) in RCA: 128] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2012] [Revised: 05/06/2014] [Accepted: 06/03/2014] [Indexed: 10/25/2022]
Abstract
Variant surface antigens play an important role in Plasmodium falciparum malaria pathogenesis and in immune evasion by the parasite. Although most work to date has focused on P. falciparum Erythrocyte Membrane Protein 1 (PfEMP1), two other multigene families encoding STEVOR and RIFIN are expressed in invasive merozoites and on the infected erythrocyte surface. However, their role during parasite infection remains to be clarified. Here we report that STEVOR functions as an erythrocyte-binding protein that recognizes Glycophorin C (GPC) on the red blood cell (RBC) surface and that its binding correlates with the level of GPC on the RBC surface. STEVOR expression on the RBC leads to PfEMP1-independent binding of infected RBCs to uninfected RBCs (rosette formation), while antibodies targeting STEVOR in the merozoite can effectively inhibit invasion. Our results suggest a PfEMP1-independent role for STEVOR in enabling infected erythrocytes at the schizont stage to form rosettes and in promoting merozoite invasion.
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Affiliation(s)
- Makhtar Niang
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Amy Kristine Bei
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | - Kripa Gopal Madnani
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Shaaretha Pelly
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Selasi Dankwa
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | - Usheer Kanjee
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | - Karthigayan Gunalan
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Anburaj Amaladoss
- Singapore-MIT Alliance for Research and Technology (SMART)-Interdisciplinary Research Group in Infectious Diseases, Singapore 117456, Singapore
| | - Kim Pin Yeo
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Ndeye Sakha Bob
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Benoit Malleret
- Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore 117545, Singapore; Singapore Immunology Network, A(∗)STAR, Singapore 138648, Singapore
| | - Manoj Theodore Duraisingh
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | - Peter Rainer Preiser
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore.
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15
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Bachmann A, Scholz JAM, Janßen M, Klinkert MQ, Tannich E, Bruchhaus I, Petter M. A comparative study of the localization and membrane topology of members of the RIFIN, STEVOR and PfMC-2TM protein families in Plasmodium falciparum-infected erythrocytes. Malar J 2015; 14:274. [PMID: 26173856 PMCID: PMC4502930 DOI: 10.1186/s12936-015-0784-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 06/27/2015] [Indexed: 12/12/2022] Open
Abstract
Background Variant surface antigens (VSA) exposed on the membrane of Plasmodium falciparum infected erythrocytes mediate immune evasion and are important pathogenicity factors in malaria disease. In addition to the well-studied PfEMP1, the small VSA families RIFIN, STEVOR and PfMC-2TM are assumed to play a role in this process. Methods This study presents a detailed comparative characterization of the localization, membrane topology and extraction profile across the life cycle of various members of these protein families employing confocal microscopy, immunoelectron microscopy and immunoblots. Results The presented data reveal a clear association of variants of the RIFIN, STEVOR and PfMC-2TM proteins with the host cell membrane and topological studies indicate that the semi-conserved N-terminal region of RIFINs and some STEVOR proteins is exposed at the erythrocyte surface. At the Maurer’s clefts, the semi-conserved N-terminal region as well as the variable stretch of RIFINs appears to point to the lumen away from the erythrocyte cytoplasm. These results challenge the previously proposed two transmembrane topology model for the RIFIN and STEVOR protein families and suggest that only one hydrophobic region spans the membrane. In contrast, PfMC-2TM proteins indeed seem to be anchored by two hydrophobic stretches in the host cell membrane exposing just a few, variable amino acids at the surface of the host cell. Conclusion Together, the host cell surface exposure and topology of RIFIN and STEVOR proteins suggests members of these protein families may indeed be involved in immune evasion of the infected erythrocyte, whereas members of the PfMC-2TM family seem to bear different functions in parasite biology. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0784-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Anna Bachmann
- Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Straße 74, 20359, Hamburg, Germany.
| | - Judith Anna Marie Scholz
- Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Straße 74, 20359, Hamburg, Germany.
| | - Marthe Janßen
- Department of Immunology, Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Straße 74, 20359, Hamburg, Germany. .,CRTD/DFG-Center for Regenerative Therapies Dresden, Technical University Dresden, Fetscherstraße 105, 01307, Dresden, Germany.
| | - Mo-Quen Klinkert
- Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Straße 74, 20359, Hamburg, Germany.
| | - Egbert Tannich
- Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Straße 74, 20359, Hamburg, Germany.
| | - Iris Bruchhaus
- Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Straße 74, 20359, Hamburg, Germany.
| | - Michaela Petter
- Department of Medicine, The Peter Doherty Institute, The University of Melbourne, 792n Elizabeth Street, Melbourne, 3000, VIC, Australia.
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16
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Tibúrcio M, Sauerwein R, Lavazec C, Alano P. Erythrocyte remodeling by Plasmodium falciparum gametocytes in the human host interplay. Trends Parasitol 2015; 31:270-8. [PMID: 25824624 DOI: 10.1016/j.pt.2015.02.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 02/20/2015] [Accepted: 02/26/2015] [Indexed: 12/31/2022]
Abstract
The spread of malaria critically relies on the presence of Plasmodium transmission stages - the gametocytes - circulating in the blood of an infected individual, which are taken up by Anopheles mosquitoes. A striking feature of Plasmodium falciparum gametocytes is their long development inside the erythrocytes while sequestered in the internal organs of the human host. Recent studies of the molecular and cellular remodeling of the host erythrocyte induced by P. falciparum during gametocyte maturation are shedding light on how these may affect the establishment and maintenance of sequestration of the immature transmission stages and the subsequent release and circulation of mature gametocytes in the peripheral bloodstream.
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Affiliation(s)
- Marta Tibúrcio
- Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate, Istituto Superiore di Sanità, Viale Regina Elena n.299, 00161 Rome, Italy
| | - Robert Sauerwein
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Nijmegen HB 6500, The Netherlands
| | - Catherine Lavazec
- Institut Cochin, INSERM U1016, CNRS UMR8104, Université Paris Descartes - Sorbonne Paris Cité, 75270 Paris, France
| | - Pietro Alano
- Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate, Istituto Superiore di Sanità, Viale Regina Elena n.299, 00161 Rome, Italy.
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17
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Tembo DL, Montgomery J, Craig AG, Wassmer SC. A simple protocol for platelet-mediated clumping of Plasmodium falciparum-infected erythrocytes in a resource poor setting. J Vis Exp 2013:e4316. [PMID: 23711755 PMCID: PMC3684037 DOI: 10.3791/4316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
P. falciparum causes the majority of severe malarial infections. The pathophysiological mechanisms underlying cerebral malaria (CM) are not fully understood and several hypotheses have been put forward, including mechanical obstruction of microvessels by P. falciparum-parasitized red blood cells (pRBC). Indeed, during the intra-erythrocytic stage of its life cycle, P. falciparum has the unique ability to modify the surface of the infected erythrocyte by exporting surface antigens with varying adhesive properties onto the RBC membrane. This allows the sequestration of pRBC in multiple tissues and organs by adhesion to endothelial cells lining the microvasculature of post-capillary venules 1. By doing so, the mature forms of the parasite avoid splenic clearance of the deformed infected erythrocytes 2 and restrict their environment to a more favorable low oxygen pressure 3. As a consequence of this sequestration, it is only immature asexual parasites and gametocytes that can be detected in peripheral blood. Cytoadherence and sequestration of mature pRBC to the numerous host receptors expressed on microvascular beds occurs in severe and uncomplicated disease. However, several lines of evidence suggest that only specific adhesive phenotypes are likely to be associated with severe pathological outcomes of malaria. One example of such specific host-parasite interactions has been demonstrated in vitro, where the ability of intercellular adhesion molecule-1 to support binding of pRBC with particular adhesive properties has been linked to development of cerebral malaria 4,5. The placenta has also been recognized as a site of preferential pRBC accumulation in malaria-infected pregnant women, with chondrotin sulphate A expressed on syncytiotrophoblasts that line the placental intervillous space as the main receptor 6. Rosetting of pRBC to uninfected erythrocytes via the complement receptor 1 (CD35)7,8 has also been associated with severe disease 9. One of the most recently described P. falciparum cytoadherence phenotypes is the ability of the pRBC to form platelet-mediated clumps in vitro. The formation of such pRBC clumps requires CD36, a glycoprotein expressed on the surface of platelets. Another human receptor, gC1qR/HABP1/p32, expressed on diverse cell types including endothelial cells and platelets, has also been shown to facilitate pRBC adhesion on platelets to form clumps 10. Whether clumping occurs in vivo remains unclear, but it may account for the significant accumulation of platelets described in brain microvasculature of Malawian children who died from CM 11. In addition, the ability of clinical isolate cultures to clump in vitro was directly linked to the severity of disease in Malawian 12 and Mozambican patients 13, (although not in Malian 14). With several aspects of the pRBC clumping phenotype poorly characterized, current studies on this subject have not followed a standardized procedure. This is an important issue because of the known high variability inherent in the assay 15. Here, we present a method for in vitro platelet-mediated clumping of P. falciparum with hopes that it will provide a platform for a consistent method for other groups and raise awareness of the limitations in investigating this phenotype in future studies. Being based in Malawi, we provide a protocol specifically designed for a limited resource setting, with the advantage that freshly collected clinical isolates can be examined for phenotype without need for cryopreservation.
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18
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The sensing of poorly deformable red blood cells by the human spleen can be mimicked in vitro. Blood 2010; 117:e88-95. [PMID: 21163923 DOI: 10.1182/blood-2010-10-312801] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Retention of poorly deformable red blood cells (RBCs) by the human spleen has been recognized as a critical determinant of pathogenesis in hereditary spherocytosis, malaria, and other RBC disorders. Using an ex vivo perfusion system, we had previously shown that retention of Plasmodium falciparum-infected RBCs (Pf-RBCs) occur in the splenic red pulp, upstream from the sinus wall. To experimentally replicate the mechanical sensing of RBCs by the splenic microcirculation, we designed a sorting device where a mixture of 5- to 25-μm-diameter microbeads mimics the geometry of narrow and short interendothelial splenic slits. Heated RBCs, Pf-RBCs, and RBCs from patients with hereditary spherocytosis were retained in the microbead layer, without hemolysis. The retention rates of Pf-RBCs were similar in microbeads and in isolated perfused human spleens. These in vitro results directly confirm the importance of the mechanical sensing of RBCs by the human spleen. In addition, rigid and deformable RBC subpopulations could be separated and characterized at the molecular level, and the device was used to deplete a stored RBC population from its subpopulation of rigid RBCs. This experimental approach may contribute to a better understanding of the role of the spleen in the pathogenesis of inherited and acquired RBC disorders.
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19
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Jemmely NY, Niang M, Preiser PR. Small variant surface antigens and Plasmodium evasion of immunity. Future Microbiol 2010; 5:663-82. [PMID: 20353305 DOI: 10.2217/fmb.10.21] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Antigenic variation at the Plasmodium-infected erythrocyte surface plays a critical role in malaria disease severity and host immune evasion. Our current understanding of the role of Plasmodium variant surface antigens in antigenic variation and immune evasion is largely limited to the extensive work carried out on the Plasmodium falciparum var gene family. Although homologues of var genes are not present in other malaria species, small variant gene families comprising the rif and stevor genes in P. falciparum and the pir genes in Plasmodium vivax, Plasmodium knowlesi and the rodent malaria Plasmodium chabaudi, Plasmodium berghei and Plasmodium yoelii also show features suggesting a role in antigenic variation and immune evasion. In this article, we highlight our current understanding of these variant antigens and provide insights on the mechanisms developed by malaria parasites to effectively avoid the host immune response and establish chronic infection.
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Affiliation(s)
- Noelle Yvonne Jemmely
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore.
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20
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Ndam NT, Deloron P. Molecular aspects of Plasmodium falciparum Infection during pregnancy. J Biomed Biotechnol 2010; 2007:43785. [PMID: 17641725 PMCID: PMC1906705 DOI: 10.1155/2007/43785] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2006] [Accepted: 03/21/2007] [Indexed: 11/17/2022] Open
Abstract
Cytoadherence of Plasmodium-falciparum-parasitized red blood cells (PRBCs) to host receptors is the key phenomenon in the pathological process of the malaria disease. Some of these interactions can originate poor outcomes responsible for 1 to 3 million annual deaths mostly occurring among children in sub-Saharan Africa. Pregnancy-associated malaria (PAM) represents an important exception of the disease occurring at adulthood in malaria endemic settings. Consequences of this are shared between the mother (maternal anemia) and the baby (low birth weight and infant mortality). Demonstrating that parasites causing PAM express specific variant surface antigens (VSA(PAM)), including the P. falciparum erythrocyte membrane protein 1 (P f EMP1) variant VAR2CSA, that are targets for protective immunity has strengthened the possibility for the development of PAM-specific vaccine. In this paper, we review the molecular basis of malaria pathogenesis attributable to the erythrocyte stages of the parasites, and findings supporting potential anti-PAM vaccine components evidenced in PAM.
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Affiliation(s)
- Nicaise Tuikue Ndam
- UR 010, Laboratoire de Parasitologie, Institut de Recherche pour le Développement, Université Paris Descartes, IFR 71, 4 avenue de l'Observatoire, 75006 Paris, France
- *Nicaise Tuikue Ndam:
| | - Philippe Deloron
- UR 010, Laboratoire de Parasitologie, Institut de Recherche pour le Développement, Université Paris Descartes, IFR 71, 4 avenue de l'Observatoire, 75006 Paris, France
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21
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Bachmann A, Esser C, Petter M, Predehl S, von Kalckreuth V, Schmiedel S, Bruchhaus I, Tannich E. Absence of erythrocyte sequestration and lack of multicopy gene family expression in Plasmodium falciparum from a splenectomized malaria patient. PLoS One 2009; 4:e7459. [PMID: 19826486 PMCID: PMC2758591 DOI: 10.1371/journal.pone.0007459] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Accepted: 09/16/2009] [Indexed: 11/19/2022] Open
Abstract
Background To avoid spleen-dependent killing mechanisms parasite-infected erythrocytes (IE) of Plasmodium falciparum malaria patients have the capacity to bind to endothelial receptors. This binding also known as sequestration, is mediated by parasite proteins, which are targeted to the erythrocyte surface. Candidate proteins are those encoded by P. falciparum multicopy gene families, such as var, rif, stevor or PfMC-2TM. However, a direct in vivo proof of IE sequestration and expression of multicopy gene families is still lacking. Here, we report on the analysis of IE from a black African immigrant, who received the diagnosis of a malignant lymphoproliferative disorder and subsequently underwent splenectomy. Three weeks after surgery, the patient experienced clinical falciparum malaria with high parasitemia and circulating developmental parasite stages usually sequestered to the vascular endothelium such as late trophozoites, schizonts or immature gametocytes. Methodology/Principal Findings Initially, when isolated from the patient, the infected erythrocytes were incapable to bind to various endothelial receptors in vitro. Moreover, the parasites failed to express the multicopy gene families var, A-type rif and stevor but expression of B-type rif and PfMC-2TM genes were detected. In the course of in vitro cultivation, the parasites started to express all investigated multicopy gene families and concomitantly developed the ability to adhere to endothelial receptors such as CD36 and ICAM-1, respectively. Conclusion/Significance This case strongly supports the hypothesis that parasite surface proteins such as PfEMP1, A-type RIFIN or STEVOR are involved in interactions of infected erythrocytes with endothelial receptors mediating sequestration of mature asexual and immature sexual stages of P. falciparum. In contrast, multicopy gene families coding for B-type RIFIN and PfMC-2TM proteins may not be involved in sequestration, as these genes were transcribed in infected but not sequestered erythrocytes.
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Affiliation(s)
- Anna Bachmann
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Claudia Esser
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Michaela Petter
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Sabine Predehl
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Vera von Kalckreuth
- Department of Tropical Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Stefan Schmiedel
- Department of Tropical Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Iris Bruchhaus
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Egbert Tannich
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- * E-mail:
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22
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Abstract
The persistence of the human malaria parasite Plasmodium falciparum during blood stage proliferation in its host depends on the successive expression of variant molecules at the surface of infected erythrocytes. This variation is mediated by the differential control of a family of surface molecules termed PfEMP1 encoded by approximately 60 var genes. Each individual parasite expresses a single var gene at a time, maintaining all other members of the family in a transcriptionally silent state. PfEMP1/var enables parasitized erythrocytes to adhere within the microvasculature, resulting in severe disease. This review highlights key regulatory mechanisms thought to be critical for monoallelic expression of var genes. Antigenic variation is orchestrated by epigenetic factors including monoallelic var transcription at separate spatial domains at the nuclear periphery, differential histone marks on otherwise identical var genes, and var silencing mediated by telomeric heterochromatin. In addition, controversies surrounding var genetic elements in antigenic variation are discussed.
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Affiliation(s)
- Artur Scherf
- Biology of Host-Parasite Interactions Unit, CNRS URA2581, Institut Pasteur 75724 Paris, France.
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23
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Garcia CRS, de Azevedo MF, Wunderlich G, Budu A, Young JA, Bannister L. Plasmodium in the postgenomic era: new insights into the molecular cell biology of malaria parasites. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 266:85-156. [PMID: 18544493 DOI: 10.1016/s1937-6448(07)66003-1] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In this review, we bring together some of the approaches toward understanding the cellular and molecular biology of Plasmodium species and their interaction with their host red blood cells. Considerable impetus has come from the development of new methods of molecular genetics and bioinformatics, and it is important to evaluate the wealth of these novel data in the context of basic cell biology. We describe how these approaches are gaining valuable insights into the parasite-host cell interaction, including (1) the multistep process of red blood cell invasion by the merozoite; (2) the mechanisms by which the intracellular parasite feeds on the red blood cell and exports parasite proteins to modify its cytoadherent properties; (3) the modulation of the cell cycle by sensing the environmental tryptophan-related molecules; (4) the mechanism used to survive in a low Ca(2+) concentration inside red blood cells; (5) the activation of signal transduction machinery and the regulation of intracellular calcium; (6) transfection technology; and (7) transcriptional regulation and genome-wide mRNA studies in Plasmodium falciparum.
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Affiliation(s)
- Celia R S Garcia
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, CEP 05508-900, São Paulo, SP, Brazil
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Richie T. High road, low road? Choices and challenges on the pathway to a malaria vaccine. Parasitology 2007; 133 Suppl:S113-44. [PMID: 17274843 DOI: 10.1017/s0031182006001843] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Malaria causes much physical and economic hardship in endemic countries with billions of people at risk. A vaccine would clearly benefit these countries, reducing the requirement for hospital care and the economic impact of infection. Successful immunization with irradiated sporozoites and the fact that repeated exposure to malaria induces partial immunity to infection and high levels of protection against the clinical manifestations, suggest that a vaccine is feasible. Numerous candidate antigens have been identified but the vaccine, which has been promised to be 'just round the corner' for many years, remains elusive. The factors contributing to this frustratingly slow progress are discussed including gaps in the knowledge of host/parasite biology, methods to induce potent cell-mediated immune responses, the difficulties associated with defining immune correlates of protection and antigen production and delivery. Finally, the use of attenuated organism vaccines is discussed.
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Affiliation(s)
- T Richie
- Malaria Program, Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, Maryland 20910-7500, USA.
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25
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Patarroyo ME, Bermúdez A, Salazar LM, Espejo F. High non-protective, long-lasting antibody levels in malaria are associated with haplotype shifting in MHC–peptide–TCR complex formation: a new mechanism for immune evasion. Biochimie 2006; 88:775-84. [PMID: 16483708 DOI: 10.1016/j.biochi.2006.01.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2005] [Accepted: 01/06/2006] [Indexed: 11/19/2022]
Abstract
An effective malarial vaccine must contain multiple immunogenic, protection-inducing epitopes able to block and destroy the P. falciparum malaria parasite, the most lethal form of this disease in the world. Our strategy has consisted in using conserved peptides blocking parasite binding to red blood cells; however, these peptides are non-immunogenic and non-protection-inducing. Modifying their critical residues can make them immunogenic. Such peptides induced antibody titers (determined by immunofluorescence antibody test, IFA) and made the latter reactive (determined by Western blot) and protection inducing against experimental challenge with a highly infective Aotus monkey adapted P. falciparum strain. Modified peptides also induce highly non-protective long-lasting antibody levels. Modifications performed might allow them to bind specifically to different HLA-DRbeta purified molecules. These immunological and biological activities are associated with modifications in their three-dimensional structure as determined by (1)H-NMR. It was found that modified, high non-protective long-lasting antibody level peptides bound to HLA-DR molecules from a different haplotype (to which immunogenic, protection-inducers bind) and had 4.6 +/- 1.4 A shorter distances between residues fitting into these molecules' Pocket 1 to Pocket 9, suggesting fitting into an inappropriate HLA-DR molecule. A multi-component, subunit-based, malarial vaccine is therefore feasible if modified peptides are suitably modified for an appropriate fit into the correct HLA-DRbeta1* molecule in order to form a proper MHC-II-peptide-TCR complex.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antibodies, Protozoan/immunology
- Aotidae
- Blotting, Western
- Computer Simulation
- HLA-DR Antigens/chemistry
- HLA-DR Antigens/immunology
- HLA-DR Antigens/metabolism
- Humans
- Major Histocompatibility Complex/immunology
- Malaria/immunology
- Malaria Vaccines/immunology
- Malaria Vaccines/metabolism
- Models, Molecular
- Molecular Sequence Data
- Peptides/chemical synthesis
- Peptides/chemistry
- Peptides/immunology
- Plasmodium falciparum/immunology
- Protein Binding
- Protein Conformation
- Receptors, Antigen, T-Cell/chemistry
- Receptors, Antigen, T-Cell/immunology
- Receptors, Antigen, T-Cell/metabolism
- Sequence Homology, Amino Acid
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Affiliation(s)
- Manuel E Patarroyo
- Fundación Instituto de Inmunología de Colombia (FIDIC), Cra. 50 No. 26-00 Bogotá, Colombia.
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26
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Ndungu FM, Urban BC, Marsh K, Langhorne J. Regulation of immune response by Plasmodium-infected red blood cells. Parasite Immunol 2005; 27:373-84. [PMID: 16179031 DOI: 10.1111/j.1365-3024.2005.00771.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
During the asexual blood stage infection of the human malaria parasite, Plasmodium falciparum, parasite-derived proteins are inserted onto the surface of the host red blood cell membrane. These proteins are highly variable and were originally thought only to mediate antigenic variation, and sequestration of parasites from peripheral circulation, thus enabling immune evasion. Recent studies have revealed that PfEMP-1 and other molecules on the P. falciparum-infected red blood cell (PfRBC) activate and modulate the immune response. In this review, we discuss how PfRBCs interact with antigen-presenting cells (APCs) and other cells of the immune system, and how such interactions could modulate the host response to Plasmodium infections.
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Affiliation(s)
- F M Ndungu
- National Institute for Medical Research, Division of Parasitology, The Ridgeway, Mill Hill, London, NW7 1AA, UK
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27
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Bach O, Baier M, Pullwitt A, Fosiko N, Chagaluka G, Kalima M, Pfister W, Straube E, Molyneux M. Falciparum malaria after splenectomy: a prospective controlled study of 33 previously splenectomized Malawian adults. Trans R Soc Trop Med Hyg 2005; 99:861-7. [PMID: 16099487 DOI: 10.1016/j.trstmh.2005.03.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2004] [Revised: 03/07/2005] [Accepted: 03/28/2005] [Indexed: 11/16/2022] Open
Abstract
We identified 33 Malawians who had undergone total splenectomy for traumatic injury. We reviewed these and 33 controls by clinical and parasitological examination monthly for 1 year. Splenectomized patients (S) were 2.5 times as likely as controls (C) to complain about febrile symptoms during the month preceding a visit (P < 0.0001). They were nearly twice as likely as controls to have Plasmodium falciparum parasitaemia (S: 176/283 person visits; C: 86/262; P < 0.0001). Parasitaemia was more likely to be associated with febrile symptoms in splenectomized individuals (S: 104/176, 59%; C: 24/86, 28%; P < 0.0001). There were three deaths (two non-malarial, one unexplained) among splenectomized subjects and none in the control group. Parasite densities reached significantly higher levels, and mature parasite stages were more often seen in the peripheral blood, in asplenic individuals. In a partially immune population, asplenic individuals are at increased risk of malarial infections and illness. In a larger group without the benefit of regular review and prompt therapy, there may be an increased risk of life-threatening malaria. Splenectomy should be avoided when possible in an area with endemic transmission of P. falciparum.
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Affiliation(s)
- Olaf Bach
- Faculty of Medicine, Department of Trauma Hand and Reconstructive Surgery, University of Jena, 07740 Jena, Germany.
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28
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Wunderlich G, Alves FP, Gölnitz U, Tada MS, Camargo EFPD, Pereira-da-Silva LH. Rapid turnover of Plasmodium falciparum var gene transcripts and genotypes during natural non-symptomatic infections. Rev Inst Med Trop Sao Paulo 2005; 47:195-201. [PMID: 16138199 DOI: 10.1590/s0036-46652005000400004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The var genes of Plasmodium falciparum code for the antigenically variant erythrocyte membrane proteins 1 (PfEMP1), a major factor for cytoadherence and immune escape of the parasite. Herein, we analyzed the var gene transcript turnover in two ongoing, non-symptomatic infections at sequential time points during two weeks. The number of different circulating genomes was estimated by microsatellite analyses. In both infections, we observed a rapid turnover of plasmodial genotypes and var transcripts. The rapidly changing repertoire of var transcripts could have been caused either by swift elimination of circulating var-transcribing parasites stemming from different or identical genetic backgrounds, or by accelerated switching of var gene transcription itself.
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Affiliation(s)
- Gerhard Wunderlich
- Departamento de Parasitologia, Instituto de Ciências Biomédicas 2, Universidade de São Paulo, 05508-900 São Paulo, SP, Brazil.
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29
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Ferreira MU, da Silva Nunes M, Wunderlich G. Antigenic diversity and immune evasion by malaria parasites. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 2005; 11:987-95. [PMID: 15539495 PMCID: PMC524792 DOI: 10.1128/cdli.11.6.987-995.2004] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Marcelo U Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1374, 05508-900 São Paulo (SP), Brazil.
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30
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del Portillo HA, Lanzer M, Rodriguez-Malaga S, Zavala F, Fernandez-Becerra C. Variant genes and the spleen in Plasmodium vivax malaria. Int J Parasitol 2005; 34:1547-54. [PMID: 15582531 DOI: 10.1016/j.ijpara.2004.10.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2004] [Revised: 10/18/2004] [Accepted: 10/18/2004] [Indexed: 11/29/2022]
Abstract
It is generally accepted that Plasmodium vivax, the most widely distributed human malaria, does not cytoadhere in the deep capillaries of inner organs and thus this malaria parasite must have evolved splenic evasion mechanism in addition to sequestration. The spleen is a uniquely adapted lymphoid organ whose central function is the selective clearance of cell and other particles from the blood, and microbes including malaria. Splenomegaly is a hallmark of malaria and no other disease seems to exacerbate this organ as this disease does. Besides this major selective clearance function however, the spleen is also an erythropoietic organ which, under stress conditions, can be responsible for close to 40% of the RBC populations. Data obtained in experimental infections of human patients with P. vivax showed that anaemia is associated with acute and chronic infections and it has been postulated that the continued parasitemia might have been sufficient to infect and destroy most circulating reticulocytes. We review here the basis of our current knowledge of variant genes in P. vivax and the structure and function of the spleen during malaria. Based on this data, we propose that P. vivax specifically adhere to barrier cells in the human spleen allowing the parasite to escape spleen-clearance while favouring the release of merozoites in an environment where reticulocytes, the predominant, if not exclusive, host cell of P. vivax, are stored before their release into circulation to compensate for the anaemia associated with vivax malaria.
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Affiliation(s)
- Hernando A del Portillo
- Departamento de Parasitologia, Instituto de Ciências Biomedicas, Universidade de São Paulo, Av. Lineu Prestes 1374, São Paulo, SP 05508-900, Brazil.
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31
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Vernot JP, Perez-Quintero LA, Perdomo-Arciniegas AM, Quijano S, Patarroyo ME. Herpesvirus saimiri
immortalization of
Aotus
T lymphocytes specific for an immunogenically modified peptide of
Plasmodium falciparum
merozoite surface antigen 2. Immunol Cell Biol 2005; 83:67-74. [PMID: 15661043 DOI: 10.1111/j.1440-1711.2005.01308.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The Plasmodium merozoite surface antigen 2 (MSA2) is one of several candidates for a protective vaccine against malaria. Previous studies have shown that antibodies directed against the MSA2 variable region are not protective and that constant regions are non-immunogenic. However, modified peptides derived from constant regions can be rendered immunogenic and partially protective in Aotus monkeys. In this study, we reveal the establishment, using in vitro Herpesvirus samiri (HVS) infection, of an Aotus monkey T-cell line (AnTMSA2) specific for a modified immunogenic and partially protective peptide derived from a constant and highly conserved region of MSA2 (SKYSNTFINNAYNMSIRRSM). AnTMSA2 is a CD4 T lymphocyte expressing high levels of MHC class II molecules, CD58 and CD2, which are important for proliferation and growth. AnTMSA2 proliferates specifically in response to the modified monomeric MSA2 peptide sequence. It is also capable of specific antigen recognition after glycine-cysteine-polymerized sequence processing and presentation by autologous APC. Interestingly, AnTMSA2 presents cross-reactivity with D-peptide analogues in which residues in positions 8 and 9 were changed for NDID residues. Therefore, at least for this particular sequence, polymerized D-peptides could be used for immunizing animals without losing the immunogenic epitope. AnTMSA2 presents a cytokine profile corresponding to a Th0-like pattern, which suggests that as a result of HVS immortalization AnTMSA2 is in transit from a Th2 to a Th1 pattern. Taken together our results suggest that Th2 T-cell induction and/or T-cell cross-reactivity generation by the modified peptide could be responsible for the immunogenic conversion observed in Aotus monkeys and that D-peptide analogues with longer half-lives could provide an alternative for inducing protective immunity.
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32
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Basri H, Fryauff DJ, Barcus MJ, Bangs MJ, Ayomi E, Marwoto H, Elyazar IRF, Richie TL, Baird JK. Malaria in a cohort of Javanese migrants to Indonesian Papua. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 2003; 97:543-56. [PMID: 14511552 DOI: 10.1179/000349803225001454] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The epidemiology of infection by Plasmodium falciparum and P. vivax was investigated among Javanese migrants to an endemic region of Papua, Indonesia. A cohort of 243 migrants from Java was followed for malaria in a new settlement village in the endemic Armopa area of north-eastern Papua, beginning on the day each migrant arrived in the village. The subjects were monitored during home visits (three/week) and by the twice-monthly production of bloodsmears that were checked for malarial parasites. At the end of 33 months, 159 (65%) of the subjects remained under follow-up. The prevalence of parasitaemia in the village declined from 16% among those already living there when the study began in August 1996, to 5% when the study finished in June 1999. Over this period, 596 infections by P. falciparum and 723 by P. vivax occurred in the cohort, 22 and 27 of the subjects each experiencing at least six infections by P. falciparum and P. vivax, respectively. The incidence of malarial infection was higher during the first and second years post-migration (3.2 and 2.7 infections/person-year) than during the third (1.2 infections/person-year). Although the geometric mean parasite counts for P. falciparum increased over time (1209, 1478, and 1830 parasites/microl in the first, second and third years, respectively), the corresponding values for P. vivax (497, 535 and 490 parasites/microl) showed no such trend. Only one of the nine subjects who developed severe malaria (requiring intravenous quinine therapy) was a child, giving an odds ratio for a case of severe malaria being in an adult of 6.1 (P=0.08).
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33
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34
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Peters J, Fowler E, Gatton M, Chen N, Saul A, Cheng Q. High diversity and rapid changeover of expressed var genes during the acute phase of Plasmodium falciparum infections in human volunteers. Proc Natl Acad Sci U S A 2002; 99:10689-94. [PMID: 12142467 PMCID: PMC125014 DOI: 10.1073/pnas.162349899] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2001] [Accepted: 06/11/2002] [Indexed: 11/18/2022] Open
Abstract
Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) proteins expressed on the surface of P. falciparum-infected erythrocytes undergo antigenic variation by switching the gene expressed within a repertoire of approximately 50 var genes per haploid genome. The switching of PfEMP1 plays an important role in the survival and pathogenesis of the parasite. To understand how a parasite switches its var gene expression in human infections, we investigated the composition and change of var gene transcripts during the acute phase of well-defined laboratory-induced P. falciparum infections in naive human hosts. Multiple var transcripts, with the same dominant transcript, were identified in samples collected after three to four asexual-parasite cycles in two volunteers infected with cloned 3D7 P. falciparum via mosquito bites. A major change in composition and frequency of var gene transcripts was observed between the culture used to infect the mosquitoes and the parasites recovered from the infected volunteers. A further change was seen when infected blood from a mosquito-infected volunteer was either passaged to other volunteers or cultured in vitro. The diversity of var transcripts did not increase with time. The results suggest that the switch of var gene expression is reinitiated after mosquito transmission and that var genes may rapidly switch from the first gene expressed after liver stage, but subsequent switching occurs at a much lower rate.
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Affiliation(s)
- Jennifer Peters
- Malaria Laboratory, Infectious Diseases Unit, Queensland Institute of Medical Research, Post Office Royal Brisbane Hospital, Queensland 4029, Australia
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35
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Malaguarnera L, Musumeci S. The immune response to Plasmodium falciparum malaria. THE LANCET. INFECTIOUS DISEASES 2002; 2:472-8. [PMID: 12150846 DOI: 10.1016/s1473-3099(02)00344-4] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Malaria is still a major cause of severe disease which is responsible for millions of deaths, mostly in children under 5 years old, in tropical countries, especially sub-Saharan Africa. Complications of severe anaemia and cerebral malaria are thought to be the major cause of morbidity and mortality but recent evidence suggests that the host's immunological response could also contribute to the pathophysiology of the disease in human beings. Intensive studies of the immune response to malaria parasites in human beings have provided a wealth of information about the cells and cytokines implicated in the pathophysiology of survival and fatal outcome in severe infections. This review focuses on the pivotal role of macrophages and other important cellular effectors, molecules, and cytokines involved in the activation of the immune response at the different stages of human falciparum malaria. Our understanding of the putative mechanisms by which cytokines may mediate beneficial and harmful effects, through activation of phagocytic cells, could help to develop new treatment strategies, regardless of the emergence of parasite multidrug resistance.
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36
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Janssen CS, Barrett MP, Turner CMR, Phillips RS. A large gene family for putative variant antigens shared by human and rodent malaria parasites. Proc Biol Sci 2002; 269:431-6. [PMID: 11886633 PMCID: PMC1690903 DOI: 10.1098/rspb.2001.1903] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A major mechanism whereby malaria parasites evade the host immune response to give chronic infections in patients' blood for months, or even years, is antigenic variation. In order to generate variant antigens, parasites require large multigene families. Although several gene families involved in these phenomena have been identified in the human malaria Plasmodium falciparum, to date no variant antigen gene families have been identified in malaria species that will infect widely used rodent laboratory hosts. Here we present, for the first time, to our knowledge, a large multigene family conserved in both rodent and human malarias, which is a strong candidate as a major variant antigen gene family. In each of four species of Plasmodium, three rodent malarias and the human pathogen P. vivax, homologues of the gene family were found to have a conserved three-exon structure. In the rodent malaria P. chabaudi, transcription of members of the gene family was developmentally regulated with maximum expression in late trophozoite stages, which is the developmental stage known to express variant antigen proteins.
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Affiliation(s)
- Christoph S Janssen
- Division of Infection and Immunity, IBLS, University of Glasgow, Glasgow G12 8QQ, UK
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37
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Abstract
Malaria causes much physical and economic hardship in tropical regions, particularly in communities where medical care is rudimentary. Should a vaccine be developed, it is the residents of these areas that stand to benefit the most. But the vaccine, which has been promised to be 'just round the corner' for many years, remains elusive. It is important to ask why this is so, when effective vaccines exist for many other infectious diseases. What are the reasons for the slow rate of progress, and what has been learned from the first clinical trials of candidate malaria vaccines? What are the remaining challenges, and what strategies can be pursued to address them?
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Affiliation(s)
- Thomas L Richie
- Malaria Program, Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, Maryland 20910-7500, USA.
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38
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O'Connor RM, Thorpe CM, Cevallos AM, Ward HD. Expression of the highly polymorphic Cryptosporidium parvum Cpgp40/15 gene in genotype I and II isolates. Mol Biochem Parasitol 2002; 119:203-15. [PMID: 11814572 DOI: 10.1016/s0166-6851(01)00416-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The enteric protozoan Cryptosporidium parvum infects intestinal epithelial cells in a wide range of hosts, causing severe gastrointestinal disease. The invasive sporozoite stage most likely attaches to and invades host cells through multiple host receptor/parasite ligand interactions. Preliminary evidence suggests that the glycoprotein products of the Cpgp40/15 gene, gp40 and gp15, are involved in these interactions. In addition, the Cpgp40/15 gene that encodes these glycopeptides is highly polymorphic in genotype I isolates, suggesting that the gene products may be subject to immune selection. In this study, we characterized the Cpgp40/15 gene in a genotype I isolate and compared expression of the Cpgp40/15 gene in isolates of both genotype. Cpgp40/15 is a single copy gene in both TU502 (genotype I) and GCH1 (genotype II) isolates. However, Northern blot analysis revealed the presence of two transcripts, 2.3 and 1.5 kb in size, in mRNA from GCH1 as well as TU502-infected Caco-2A cells. Accumulation of the two Cpgp40/15 mRNAs peaked 12-24 h post-infection. Using 3'RACE analysis, three polyadenylation sites were identified 371, 978 and 1002 bp downstream of the GCH1 Cpgp40/15 stop codon. Two of these polyadenylation sites were also used in TU502. The sequences of the GCH1 Cpgp40/15 3'untranslated regions (3'UTRs) were identical to genomic sequence and shared 96.7% homology with TU502 3'UTRs. Actinomycin D treatment of GCH1-infected Caco-2A cells followed by Northern blot analysis, revealed that the stability of the 1.5 kb message was considerably greater than that of the 2.3 kb transcript.
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Affiliation(s)
- Roberta M O'Connor
- Division of Geographic Medicine and Infectious Diseases, New England Medical Center, Tufts University School of Medicine, Box 041, 750 Washington Street, Boston, MA 02111, USA.
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39
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Abstract
Many pathogens that either rely on an insect vector to complete their life cycle (e.g., Trypanosoma spp. and Borrelia spp.) or exist in a unique ecological niche where transmission from host to host is sporadic (e.g., Neisseria spp.) have evolved strategies to maintain infection of their mammalian hosts for long periods of time in order to ensure their survival. Because they have to survive in the face of a fully functional immune system, a common feature of many of these organisms is their development of sophisticated strategies for immune evasion. For the above organisms and for malaria parasites of the genus Plasmodium, a common theme is the ability to undergo clonal antigenic variation. In all cases, surface molecules that are important targets of the humoral immune response are encoded in the genome as multicopy, nonallelic gene families. Antigenic variation is accomplished by the successive expression of members of these gene families that show little or no immunological cross-reactivity. In the case of malaria parasites, however, some of the molecules that undergo antigenic variation are also major virulence factors, adding an additional level of complication to the host-parasite interaction. In this review, we cover the history of antigenic variation in malaria and then summarize the more recent data with particular emphasis on Plasmodium falciparum, the etiological agent of the most severe form of human malaria.
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Affiliation(s)
- S Kyes
- Molecular Parasitology Group, Weatherall Institute of Molecular Medicine, Headington, Oxford OX3 9DS United Kingdom.
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40
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Meunier L. Clonal variation of gene expression as a source of phenotypic diversity in parasitic protozoa. Trends Parasitol 2001; 17:475-9. [PMID: 11587961 DOI: 10.1016/s1471-4922(01)02017-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Within a cellular clone, individual cells can express different members of a gene family. If the difference in expression is transmitted to daughter cells, 'phenotypic clones' are formed. Such clonal phenotypic variation has evolved independently in phylogenetically distant parasitic protozoa under similar selective pressure: the need for phenotypic diversity at several steps of their life cycle. Here, I review clonal phenotypic variation processes, outline their role in parasite biology and argue that clonal phenotypic variation is complementary to sexual reproduction as a source of phenotypic diversity.
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Affiliation(s)
- L Meunier
- CEPM, UMR CNRS-IRD 9926, 911 Avenue Agropolis, BP 5045, 34032 Montpellier Cedex 1, France.
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41
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Affiliation(s)
- A Saul
- Malaria Vaccine Development Unit, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland 20852, USA.
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42
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Scherf A, Pouvelle B, Buffet PA, Gysin J. Molecular mechanisms of Plasmodium falciparum placental adhesion. Cell Microbiol 2001; 3:125-31. [PMID: 11260135 DOI: 10.1046/j.1462-5822.2001.00109.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In natural Plasmodium falciparum infections, parasitized erythrocytes (PEs) circulate in the peripheral blood for a period corresponding roughly to the first part of the erythrocytic life cycle (ring stage). Later, in blood-stage development, parasite-encoded adhesion molecules are inserted into the erythrocyte membrane, preventing the circulation of the PEs. The principal molecule mediating PE adhesion is P. falciparum erythrocyte membrane protein 1 (PfEMP1), encoded by the polymorphic var gene family. The population of parasites is subject to clonal antigenic variation through changes in var expression, and a single PfEMP1 variant is expressed at the PE surface in a mutually exclusive manner. In addition to its role in immune evasion, switches in PfEMP1 expression may be associated with fundamental changes in parasite tissue tropism in malaria patients. A switch from CD36 binding to chondroitin sulphate A (CSA) binding may lead to extensive sequestration of PEs in placenta syncytiotrophoblasts. This is probably a key event in malaria pathogenesis during pregnancy. The CSA-binding phenotype of mature PEs is linked to another distinct adhesive phenotype: the recently described CSA-independent cytoadhesion of ring-stage PEs. Thus, a subpopulation of PEs that sequentially displays these two different phenotypes may bind to an individual endothelial cell or syncytiotrophoblast throughout the asexual blood-stage cycle. This suggests that non-circulating (cryptic) parasite subpopulations are present in malaria patients.
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Affiliation(s)
- A Scherf
- Unité de Biologie des Interactions Hôte-Parasite, CNRS URA 1960, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris, France.
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43
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Abstract
Malaria remains one of the world's worst health problems with 1.5 to 2.7 million deaths annually; these deaths are primarily among children under 5 years of age and pregnant women in sub-Saharan Africa. Of significance, more people are dying from malaria today than 30 years ago. This review considers the factors which have contributed to this gloomy picture, including those which relate to the vector, the female anopheline mosquito; to human activity such as creating new mosquito breeding sites, the impact of increased numbers of people, and how their migratory behavior can increase the incidence and spread of malaria; and the problems of drug resistance by the parasites to almost all currently available antimalarial drugs. In a selective manner, this review describes what is being done to ameliorate this situation both in terms of applying existing methods in a useful or even crucial role in control and prevention and in terms of new additions to the antimalarial armory that are being developed. Topics covered include biological control of mosquitoes, the use of insecticide-impregnated bed nets, transgenic mosquitoes manipulated for resistance to malaria parasites, old and new antimalarial drugs, drug resistance and how best to maintain the useful life of antimalarials, immunity to malaria and the search for antimalarial vaccines, and the malaria genome project and the potential benefits to accrue from it.
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Affiliation(s)
- R S Phillips
- Division of Infection and Immunity, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
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Perlmann P, Björkman A. Malaria research: host-parasite interactions and new developments in chemotherapy, immunology and vaccinology. Curr Opin Infect Dis 2000; 13:431-443. [PMID: 11964811 DOI: 10.1097/00001432-200010000-00002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Malaria remains the major parasitic disease, with 300-500 million new infections each year. This survey covers recent advances in the field of parasite-host interactions, focusing on Plasmodium falciparum, the most virulent of the human parasites. Rapid progress in genomic research is creating a basis for the development of new drugs and vaccines. Identification of drug-resistance mutations facilitates evaluation of improved drug policies, and attempts are being made to develop new compounds that inhibit metabolic pathways that are specific to the parasite. Cytoadherence of parasitized erythrocytes to microvascular endothelium is responsible for the sequestration of parasites, causing pathology and severe disease. Newly identified molecular fine structures that mediate cytoadherence may provide new targets for specific therapies. Humoral and cell-mediated immunity induced by the parasite may be protective, but may also be harmful by generating imbalance in cytokine responses. Efforts are made to determine the pathways that give rise to protection, with vaccination being the principal goal for achieving malaria control. Different vaccine constructs are being evaluated in preclinical and clinical trials, including modified viral vectors, synthetic peptides, DNA and new adjuvants.
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Affiliation(s)
- Peter Perlmann
- aDepartment of Immunology, Stockholm University, and bKarolinska Institute, Infectious Diseases Unit, Karolinska Hospital, Stockholm, Sweden
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Preiser P, Kaviratne M, Khan S, Bannister L, Jarra W. The apical organelles of malaria merozoites: host cell selection, invasion, host immunity and immune evasion. Microbes Infect 2000; 2:1461-77. [PMID: 11099933 DOI: 10.1016/s1286-4579(00)01301-0] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Malaria is caused by protozoan parasites belonging to the phylum Apicomplexa. These obligate intracellular parasites depend on the successful invasion of an appropriate host cell for their survival. This article is a broad overview of the molecular strategies employed by the merozoite, an invasive form of the malaria parasite, to successfully invade a suitable red blood cell.
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Affiliation(s)
- P Preiser
- Division of Parasitology, The National Institute for Medical Research, The Ridgeway, Mill Hill, NW7 1AA, London, UK.
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46
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Abstract
As global malaria mortality increases the urgency for vaccine development, analysis of immune responses in naturally exposed populations is providing clues to the nature of protective immunity. Recently, sophisticated immune evasion strategies adopted by the parasite have been analysed at the molecular level. More immunogenic vaccination strategies have been identified, providing renewed optimism that effective malaria control through vaccination should be feasible.
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Affiliation(s)
- M Plebanski
- Vaccine Development and Infectious Diseases Unit, The Austin Research Institute, Heidelberg, VA 3084, Australia.
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