1
|
McLean FE, Azasi Y, Sutherland C, Toboh E, Ansong D, Agbenyega T, Awandare G, Rowe JA. Detection of naturally acquired, strain-transcending antibodies against rosetting Plasmodium falciparum strains in humans. Infect Immun 2024:e0001524. [PMID: 38842304 DOI: 10.1128/iai.00015-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 04/29/2024] [Indexed: 06/07/2024] Open
Abstract
Strain-transcending antibodies against virulence-associated subsets of P. falciparum-infected erythrocyte surface antigens could protect children from severe malaria. However, the evidence supporting the existence of such antibodies is incomplete and inconsistent. One subset of surface antigens associated with severe malaria, rosette-mediating Plasmodium falciparum Erythrocyte Membrane Protein one (PfEMP1) variants, cause infected erythrocytes to bind to uninfected erythrocytes to form clusters of cells (rosettes) that contribute to microvascular obstruction and pathology. Here, we tested plasma from 80 individuals living in malaria-endemic regions for IgG recognition of the surface of four P. falciparum rosetting strains using flow cytometry. Broadly reactive plasma samples were then used in antibody elution experiments in which intact IgG was eluted from the surface of infected erythrocytes and transferred to heterologous rosetting strains to look for strain-transcending antibodies. We found that seroprevalence (percentage of positive plasma samples) against allopatric rosetting strains was high in adults (63%-93%) but lower in children (13%-48%). Strain-transcending antibodies were present in nine out of eleven eluted antibody experiments, with six of these recognizing multiple heterologous rosetting parasite strains. One eluate had rosette-disrupting activity against heterologous strains, suggesting PfEMP1 as the likely target of the strain-transcending antibodies. Naturally acquired strain-transcending antibodies to rosetting P. falciparum strains in humans have not been directly demonstrated previously. Their existence suggests that such antibodies could play a role in clinical protection and raises the possibility that conserved epitopes recognized by strain-transcending antibodies could be targeted therapeutically by monoclonal antibodies or vaccines.
Collapse
Affiliation(s)
- Florence E McLean
- Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Yvonne Azasi
- Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Cameron Sutherland
- Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | | | - Daniel Ansong
- Kwame Nkrumah University of Science and Technology, School of Medical Sciences, Kumasi, Ghana
- Departments of Child Health and Medicine, Komfo Anokye Teaching Hospital, Kumasi, Ghana
- Malaria Research Centre, Agogo, Ghana
| | - Tsiri Agbenyega
- Kwame Nkrumah University of Science and Technology, School of Medical Sciences, Kumasi, Ghana
- Departments of Child Health and Medicine, Komfo Anokye Teaching Hospital, Kumasi, Ghana
- Malaria Research Centre, Agogo, Ghana
| | - Gordon Awandare
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Legon, Ghana
| | - J Alexandra Rowe
- Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| |
Collapse
|
2
|
Tryptophan C-mannosylation is critical for Plasmodium falciparum transmission. Nat Commun 2022; 13:4400. [PMID: 35906227 PMCID: PMC9338275 DOI: 10.1038/s41467-022-32076-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 07/07/2022] [Indexed: 11/08/2022] Open
Abstract
Tryptophan C-mannosylation stabilizes proteins bearing a thrombospondin repeat (TSR) domain in metazoans. Here we show that Plasmodium falciparum expresses a DPY19 tryptophan C-mannosyltransferase in the endoplasmic reticulum and that DPY19-deficiency abolishes C-glycosylation, destabilizes members of the TRAP adhesin family and inhibits transmission to mosquitoes. Imaging P. falciparum gametogenesis in its entirety in four dimensions using lattice light-sheet microscopy reveals defects in ΔDPY19 gametocyte egress and exflagellation. While egress is diminished, ΔDPY19 microgametes still fertilize macrogametes, forming ookinetes, but these are abrogated for mosquito infection. The gametogenesis defects correspond with destabilization of MTRAP, which we show is C-mannosylated in P. falciparum, and the ookinete defect is concordant with defective CTRP secretion on the ΔDPY19 background. Genetic complementation of DPY19 restores ookinete infectivity, sporozoite production and C-mannosylation activity. Therefore, tryptophan C-mannosylation by DPY19 ensures TSR protein quality control at two lifecycle stages for successful transmission of the human malaria parasite. Here, Lopaticki et al. show that Plasmodium falciparum expresses a Dpy19 C-mannosyltransferase in the endoplasmic reticulum that glycosylates TSR domains. Functional characterization shows that PfDpy19 plays a critical role in transmission through mosquitoes as PfDpy19-deficiency abolishes C-glycosylation and destabilizes proteins relevant for gametogenesis and oocyst formation.
Collapse
|
3
|
Nyarko PB, Claessens A. Understanding Host-Pathogen-Vector Interactions with Chronic Asymptomatic Malaria Infections. Trends Parasitol 2020; 37:195-204. [PMID: 33127332 DOI: 10.1016/j.pt.2020.09.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 09/28/2020] [Accepted: 09/30/2020] [Indexed: 01/06/2023]
Abstract
The last malaria parasite standing will display effective adaptations to selective forces. While substantial progress has been made in reducing malaria mortality, eradication will require elimination of all Plasmodium parasites, including those in asymptomatic infections. These typically chronic, low-density infections are difficult to detect, yet can persist for months. We argue that asymptomatic infection is the parasite's best asset for survival but it can be exploited if studied as a new model for host-pathogen-vector interactions. Regular sampling from cohorts of asymptomatic individuals can provide a means to investigate continuous parasite development within its natural host. State-of-the-art techniques can now be applied to such infections. This approach may reveal key molecular drivers of chronic infections - a critical step for malaria eradication.
Collapse
Affiliation(s)
- Prince B Nyarko
- Laboratory of Pathogen-Host Interaction (LPHI), CNRS, University of Montpellier, France
| | | |
Collapse
|
4
|
Zhang X, Alexander N, Leonardi I, Mason C, Kirkman LA, Deitsch KW. Rapid antigen diversification through mitotic recombination in the human malaria parasite Plasmodium falciparum. PLoS Biol 2019; 17:e3000271. [PMID: 31083650 PMCID: PMC6532940 DOI: 10.1371/journal.pbio.3000271] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 05/23/2019] [Accepted: 04/30/2019] [Indexed: 11/18/2022] Open
Abstract
Malaria parasites possess the remarkable ability to maintain chronic infections that fail to elicit a protective immune response, characteristics that have stymied vaccine development and cause people living in endemic regions to remain at risk of malaria despite previous exposure to the disease. These traits stem from the tremendous antigenic diversity displayed by parasites circulating in the field. For Plasmodium falciparum, the most virulent of the human malaria parasites, this diversity is exemplified by the variant gene family called var, which encodes the major surface antigen displayed on infected red blood cells (RBCs). This gene family exhibits virtually limitless diversity when var gene repertoires from different parasite isolates are compared. Previous studies indicated that this remarkable genome plasticity results from extensive ectopic recombination between var genes during mitotic replication; however, the molecular mechanisms that direct this process to antigen-encoding loci while the rest of the genome remains relatively stable were not determined. Using targeted DNA double-strand breaks (DSBs) and long-read whole-genome sequencing, we show that a single break within an antigen-encoding region of the genome can result in a cascade of recombination events leading to the generation of multiple chimeric var genes, a process that can greatly accelerate the generation of diversity within this family. We also found that recombinations did not occur randomly, but rather high-probability, specific recombination products were observed repeatedly. These results provide a molecular basis for previously described structured rearrangements that drive diversification of this highly polymorphic gene family.
Collapse
Affiliation(s)
- Xu Zhang
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
| | - Noah Alexander
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York, United States of America
| | - Irina Leonardi
- Jill Roberts Center for Inflammatory Bowel Disease, Weill Cornell Medical College, New York, New York, United States of America
| | - Christopher Mason
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York, United States of America
- HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine, Weill Cornell Medical College, New York, New York, United States of America
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, New York, United States of America
- WorldQuant Initiative for Quantitative Prediction, Weill Cornell Medical College, New York, New York, United States of America
| | - Laura A. Kirkman
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
- Department of Internal Medicine, Division of Infectious Diseases, Weill Cornell Medical College, New York, New York, United States of America
| | - Kirk W. Deitsch
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
- * E-mail:
| |
Collapse
|
5
|
Sondo P, Derra K, Lefevre T, Diallo-Nakanabo S, Tarnagda Z, Zampa O, Kazienga A, Valea I, Sorgho H, Ouedraogo JB, Guiguemde TR, Tinto H. Genetically diverse Plasmodium falciparum infections, within-host competition and symptomatic malaria in humans. Sci Rep 2019; 9:127. [PMID: 30644435 PMCID: PMC6333925 DOI: 10.1038/s41598-018-36493-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 11/16/2018] [Indexed: 11/17/2022] Open
Abstract
There is a large genetic diversity of Plasmodium falciparum strains that infect people causing diverse malaria symptoms. This study was carried out to explore the effect of mixed-strain infections and the extent to which some specific P. falciparum variants are associated with particular malaria symptoms. P. falciparum isolates collected during pharmacovigilance study in Nanoro, Burkina Faso were used to determine allelic variation in two polymorphic antigens of the merozoite surface (msp1 and msp2). Overall, parasite density did not increase with additional strains, suggesting the existence of within-host competition. Parasite density was influenced by msp1 allelic families with highest parasitaemia observed in MAD20 allelic family. However, when in mixed infections with allelic family K1, MAD20 could not grow to the same levels as it would alone, suggesting competitive suppression in these mixed infections. Host age was associated with parasite density. Overall, older patients exhibited lower parasite densities than younger patients, but this effect varied with the genetic composition of the isolates for the msp1 gene. There was no effect of msp1 and msp2 allelic family variation on body temperature. Haemoglobin level was influenced by msp2 family with patients harboring the FC27 allele showing lower haemoglobin level than mono-infected individuals by the 3D7 allele. This study provides evidence that P. falciparum genetic diversity influenced the severity of particular malaria symptoms and supports the existence of within-host competition in genetically diverse P. falciparum.
Collapse
Affiliation(s)
- Paul Sondo
- Institut de Recherche en Sciences de la Santé (IRSS)/Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso.
| | - Karim Derra
- Institut de Recherche en Sciences de la Santé (IRSS)/Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso
| | - Thierry Lefevre
- Institut de Recherche en Sciences de la Santé (IRSS)/Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso.,MIVEGEC, IRD, CNRS, University of Montpellier, Montpellier, France
| | - Seydou Diallo-Nakanabo
- Institut de Recherche en Sciences de la Santé (IRSS)/Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso
| | - Zekiba Tarnagda
- Institut de Recherche en Sciences de la Santé (IRSS)/Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso
| | - Odile Zampa
- Centre Muraz of Bobo-Dioulasso, Bobo-Dioulasso, Burkina Faso
| | - Adama Kazienga
- Institut de Recherche en Sciences de la Santé (IRSS)/Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso
| | - Innocent Valea
- Institut de Recherche en Sciences de la Santé (IRSS)/Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso.,Centre Muraz of Bobo-Dioulasso, Bobo-Dioulasso, Burkina Faso
| | - Hermann Sorgho
- Institut de Recherche en Sciences de la Santé (IRSS)/Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso
| | - Jean-Bosco Ouedraogo
- Institut de Recherche en Sciences de la Santé (IRSS)/Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso
| | | | - Halidou Tinto
- Institut de Recherche en Sciences de la Santé (IRSS)/Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso.,Centre Muraz of Bobo-Dioulasso, Bobo-Dioulasso, Burkina Faso
| |
Collapse
|
6
|
Kusi KA, Manu EA, Manful Gwira T, Kyei-Baafour E, Dickson EK, Amponsah JA, Remarque EJ, Faber BW, Kocken CHM, Dodoo D, Gyan BA, Awandare GA, Atuguba F, Oduro AR, Koram KA. Variations in the quality of malaria-specific antibodies with transmission intensity in a seasonal malaria transmission area of Northern Ghana. PLoS One 2017; 12:e0185303. [PMID: 28945794 PMCID: PMC5612719 DOI: 10.1371/journal.pone.0185303] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Accepted: 09/11/2017] [Indexed: 02/07/2023] Open
Abstract
Introduction Plasmodium falciparum induced antibodies are key components of anti-malarial immunity in malaria endemic areas, but their antigen targets can be polymorphic. Induction of a high proportion of strain-specific antibodies will limit the recognition of a broad diversity of parasite strains by these responses. There are indications that circulating parasite diversity varies with malaria transmission intensity, and this may affect the specificity of elicited anti-malarial antibodies. This study therefore assessed the effect of varying malaria transmission patterns on the specificity of elicited antibody responses and to identify possible antibody correlates of naturally acquired immunity to malaria in children in an area of Ghana with seasonal malaria transmission. Methods This retrospective study utilized plasma samples collected longitudinally at six time points from children aged one to five years. Multiplex assays were used to measure antibody levels against four P. falciparum AMA 1 variants (from the 3D7, FVO, HB3 and CAMP parasite strains) and the 3D7 variant of the EBA 175 region II antigen and the levels compared between symptomatic and asymptomatic children. The relative proportions of cross-reactive and strain-specific antibodies against the four AMA 1 variants per sampling time point were assessed by Bland-Altman plots. The levels of antibodies against allelic AMA1 variants, measured by singleplex and multiplex luminex assays, were also compared. Results The data show that increased transmission intensity is associated with higher levels of cross-reactive antibody responses, most likely a result of a greater proportion of multiple parasite clone infections during the high transmission period. Anti-AMA1 antibodies were however associated with a history of infection rather than protection in this age group. Conclusion The data contribute to understanding the underlying mechanism of the acquisition of strain-transcending antibody immunity following repeated exposure to diverse parasite strains.
Collapse
Affiliation(s)
- Kwadwo A. Kusi
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana
- * E-mail:
| | - Emmanuel A. Manu
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana
| | - Theresa Manful Gwira
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana
| | - Eric Kyei-Baafour
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Emmanuel K. Dickson
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Jones A. Amponsah
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Edmond J. Remarque
- Department of Parasitology, Biomedical Primate Research Centre, Rijswijk, The Netherlands
| | - Bart W. Faber
- Department of Parasitology, Biomedical Primate Research Centre, Rijswijk, The Netherlands
| | - Clemens H. M. Kocken
- Department of Parasitology, Biomedical Primate Research Centre, Rijswijk, The Netherlands
| | - Daniel Dodoo
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Ben A. Gyan
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Gordon A. Awandare
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana
| | - Frank Atuguba
- Navrongo Health Research Centre, Ghana Health Service, Navrongo, Ghana
| | - Abraham R. Oduro
- Navrongo Health Research Centre, Ghana Health Service, Navrongo, Ghana
| | - Kwadwo A. Koram
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana
- Department of Epidemiology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| |
Collapse
|
7
|
Das MK, Prajapati BK, Tiendrebeogo RW, Ranjan K, Adu B, Srivastava A, Khera HK, Chauhan N, Tevatiya S, Kana IH, Sharma SK, Singh S, Theisen M. Malaria epidemiology in an area of stable transmission in tribal population of Jharkhand, India. Malar J 2017; 16:181. [PMID: 28464875 PMCID: PMC5414148 DOI: 10.1186/s12936-017-1833-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 04/23/2017] [Indexed: 11/10/2022] Open
Abstract
Background Malaria remains an important health problem in India with approximately 1 million cases in 2014. Of these, 7% occurred in the Jharkhand state mainly in the tribal population. Methods This study was conducted in Dumargarhi, a tribal village about 42 km east of Ranchi city, Jharkhand, from May 2014 to September 2016. Four point prevalence surveys were carried out during consecutive high (October–December) and low (June–August) transmission seasons. Malaria cases were recorded from April 2015 to April 2016 through fortnightly visits to the village. Adult mosquito densities were monitored fortnightly by manual catching using suction tube method. Results The study area consists of five hamlets inhabited by 945 individuals living in 164 households as recorded through a house-to-house census survey performed at enrollment. The study population consisted predominantly of the Munda (n = 425, 45%) and Oraon (n = 217, 23%) ethnic groups. Study participants were categorized as per their age 0–5, 6–10, 11–15 and >15 years. There were 99 cases of clinical malaria from April 2015 to April 2016 and all malaria cases confirmed by microscopy were attributed to Plasmodium falciparum (94 cases) and Plasmodium vivax (5 cases), respectively. During the high transmission season the mean density of P. falciparum parasitaemia per age group increased to a peak level of 23,601 parasites/μl in the 6–10 years age group and gradually declined in the adult population. Malaria attack rates, parasite prevalence and density levels in the study population showed a gradual decrease with increasing age. This finding is consistent with the phenomenon of naturally acquired immunity against malaria. Three vector species were detected: Anopheles fluviatilis, Anopheles annularis, and Anopheles culicifacies. The incoherence or complete out of phase pattern of the vector density peaks together with a high prevalence of parasite positive individuals in the study population explains the year-round malaria transmission in the study region. Conclusions The collection of clinical data from a well-characterized tribal cohort from Jharkhand, India, has provided evidence for naturally acquired immunity against malaria in this hyperendemic region. The study also suggests that enforcement of existing control programmes can reduce the malaria burden further.
Collapse
Affiliation(s)
- Manoj K Das
- Field Unit, National Institute of Malaria Research, Ranchi, Jharkhand, India
| | - Brijesh K Prajapati
- National Institute of Malaria Research, Indian Council of Medical Research, New Delhi, 110077, India
| | - Régis W Tiendrebeogo
- Department for Congenital Disorders, Statens Serum Institut, Artillerivej 5, 2300, Copenhagen, Denmark.,Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Kumud Ranjan
- National Institute of Malaria Research, Indian Council of Medical Research, New Delhi, 110077, India
| | - Bright Adu
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Amit Srivastava
- Indian Institute of Integrative Medicine, Canal Road, Jammu, 180001, India
| | - Harvinder K Khera
- Indian Institute of Integrative Medicine, Canal Road, Jammu, 180001, India
| | - Narendra Chauhan
- Indian Institute of Integrative Medicine, Canal Road, Jammu, 180001, India
| | - Sanjay Tevatiya
- National Institute of Malaria Research, Indian Council of Medical Research, New Delhi, 110077, India
| | - Ikhlaq H Kana
- Department for Congenital Disorders, Statens Serum Institut, Artillerivej 5, 2300, Copenhagen, Denmark.,Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Surya Kant Sharma
- National Institute of Malaria Research, Indian Council of Medical Research, New Delhi, 110077, India.
| | - Subhash Singh
- Indian Institute of Integrative Medicine, Canal Road, Jammu, 180001, India.
| | - Michael Theisen
- Department for Congenital Disorders, Statens Serum Institut, Artillerivej 5, 2300, Copenhagen, Denmark. .,Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark. .,Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
| |
Collapse
|
8
|
Carlos BC, Fotoran WL, Menezes MJ, Cabral FJ, Bastos MF, Costa FT, Sousa-Neto JA, Ribolla PE, Wunderlich G, Ferreira MU. Expressed var gene repertoire and variant surface antigen diversity in a shrinking Plasmodium falciparum population. Exp Parasitol 2016; 170:90-99. [DOI: 10.1016/j.exppara.2016.09.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 09/01/2016] [Accepted: 09/20/2016] [Indexed: 10/21/2022]
|
9
|
Tan J, Bull PC. Agglutination Assays of the Plasmodium falciparum-Infected Erythrocyte. Methods Mol Biol 2015; 1325:115-129. [PMID: 26450384 PMCID: PMC6624126 DOI: 10.1007/978-1-4939-2815-6_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The agglutination assay is used to determine the ability of antibodies to recognize parasite variant antigens on the surface of Plasmodium falciparum-infected erythrocytes. In this technique, infected erythrocytes are selectively labelled with a DNA-binding fluorescent dye and mixed with antibodies of interest to allow antibody-surface antigen binding. Recognition of surface antigens by the antibodies can result in the formation of agglutinates containing multiple parasite-infected erythrocytes. These can be viewed and quantified using a fluorescence microscope.
Collapse
Affiliation(s)
- Joshua Tan
- KEMRI-Wellcome Trust Research Programme, 230-80108, Kilifi, Kenya
- Centre for Tropical Medicine, Nuffield Department of Medicine, Oxford University, Oxford, OX3 7LJ, UK
| | - Peter C Bull
- KEMRI-Wellcome Trust Research Programme, 230-80108, Kilifi, Kenya.
- Centre for Tropical Medicine, Nuffield Department of Medicine, Oxford University, Oxford, OX3 7LJ, UK.
| |
Collapse
|
10
|
Chan JA, Fowkes FJI, Beeson JG. Surface antigens of Plasmodium falciparum-infected erythrocytes as immune targets and malaria vaccine candidates. Cell Mol Life Sci 2014; 71:3633-57. [PMID: 24691798 PMCID: PMC4160571 DOI: 10.1007/s00018-014-1614-3] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 03/04/2014] [Accepted: 03/17/2014] [Indexed: 12/19/2022]
Abstract
Understanding the targets and mechanisms of human immunity to malaria caused by Plasmodium falciparum is crucial for advancing effective vaccines and developing tools for measuring immunity and exposure in populations. Acquired immunity to malaria predominantly targets the blood stage of infection when merozoites of Plasmodium spp. infect erythrocytes and replicate within them. During the intra-erythrocytic development of P. falciparum, numerous parasite-derived antigens are expressed on the surface of infected erythrocytes (IEs). These antigens enable P. falciparum-IEs to adhere in the vasculature and accumulate in multiple organs, which is a key process in the pathogenesis of disease. IE surface antigens, often referred to as variant surface antigens, are important targets of acquired protective immunity and include PfEMP1, RIFIN, STEVOR and SURFIN. These antigens are highly polymorphic and encoded by multigene families, which generate substantial antigenic diversity to mediate immune evasion. The most important immune target appears to be PfEMP1, which is a major ligand for vascular adhesion and sequestration of IEs. Studies are beginning to identify specific variants of PfEMP1 linked to disease pathogenesis that may be suitable for vaccine development, but overcoming antigenic diversity in PfEMP1 remains a major challenge. Much less is known about other surface antigens, or antigens on the surface of gametocyte-IEs, the effector mechanisms that mediate immunity, and how immunity is acquired and maintained over time; these are important topics for future research.
Collapse
|
11
|
Analysis of antibody induction upon immunization with distinct NTS-DBL1α-domains of PfEMP1 from rosetting Plasmodium falciparum parasites. Malar J 2013; 12:32. [PMID: 23347690 PMCID: PMC3599323 DOI: 10.1186/1475-2875-12-32] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 01/22/2013] [Indexed: 11/15/2022] Open
Abstract
Background Rosette-formation of Plasmodium falciparum parasitized erythrocytes is of importance in the development of severe malaria. The parasite-derived molecule PfEMP1 (Plasmodium falciparum erythrocyte membrane protein 1), central to rosetting, is suggested to be included in a multimeric vaccine targeting severe disease. Methods Three recombinant NTS-DBL1α-domains of PfEMP1 were generated in Escherichia coli, purified and used for immunization of rats and goats. Antibody titres were determined in ELISA assays and responses were compared in-between different individual animals and species. Reactivity with the parasites was tested in live pRBC using FACS. B-cell epitopes prediction was carried out in silico and compared to the results obtained by peptide microarray. Screening for serological cross-reactivity with heterologous NTS-DBL1α variants was carried out by ELISA, peptide array and FACS on pRBC of different laboratory strains and patient isolates. Results All three NTS-DBL1α-domains induced high titres of antibodies that were biologically active with no apparent difference between constructs covering slightly different parts of the DBL1α-sequence. The different animal species showed comparable titres of antibodies, while variations within individuals of the species could be observed. Mapping of the recognized epitopes revealed that most parts of the molecule were able to induce an antibody response with a tendency for the N and C terminal parts of the molecule for slightly higher recognition. Important differences to the epitopes predicted were found as some of the most conserved parts of the DBL1α-domain contained the main epitopes for antibody reactivity. ELISA assays and peptide microarray demonstrated substantial cross-reactivity to heterologous variants, while binding to native PfEMP1 was observed only in few combinations on the pRBC surface, underlining that mainly internal, conserved and not surface exposed parts of the DBL1α-domain are responsible for this observation. Conclusion Biologically active antibodies can be induced consistently, with high titres, in different animal species and the antibodies elicited by different constructs react with similar epitopes. Induced antibodies recognize epitopes localized in all subdomains of the DBL1α-sequence. Cross-reactivity between NTS-DBL1α-variants is common in ELISA, but rare with live pRBC emphasizing that also internal, conserved areas of PfEMP1 carry important highly immunogenic epitopes of the molecule.
Collapse
|
12
|
Kalantari N, Ghaffari S. Identification and Characterization of the Antigens Expressed On the Surface of Human Erythrocytes Infected With Plasmodium falciparum. IRANIAN JOURNAL OF PARASITOLOGY 2013; 8:197-206. [PMID: 23914231 PMCID: PMC3724143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Accepted: 04/20/2013] [Indexed: 11/18/2022]
Abstract
BACKGROUND Molecules expressed on the surface of infected erythrocytes (IE) with Plasmodium falciparum play important roles in malaria pathogenesis and immune evasion. Some of these molecules are specific adhesive ligands mediating adhesion of IE to the vascular endothelium. In the current study, the antigens exposed on the surface of IE with different isolates and various binding subpopulations of P. falciparum were studied. METHODS A pooled hyper immune serum (HIS) from Malawian adults and eluted antibodies from the surface of the homologous and heterologous parasites were used. The parasite surface molecules were analyzed by Immuno-Gold-Silver enhancement (IGSE) and Western blotting. Mini-column cytoadherence method was used to select various parasite-binding subpopulations. RESULTS Surface antigens of all the isolates were recognized by HIS and high recognition of antigens was observed in all isolates with homologous eluted antibodies. Western blot analysis showed that the eluted antibodies reacted with a small subset of antigens compared with HIS. Three bands, PfEMP-1, were detected in the Triton X- insoluble fraction of the ICAM-1 binding subpopulation. Another interesting band was ∼ 52-55 kDa in various isolates of P. falciparum. This molecule as defined by its low molecular weight, Triton X-100 solubility, surface location and sensitivity to 1 mg/ml trypsin. CONCLUSION The IE's surface antigens differed in parental population compared with the selected subpopulations. These molecules could induce isolate-specific immunity. Antibodies purified from the surface of IE can be used as specific reagents to investigate parasite-derived proteins expressed on the surface of IE.
Collapse
Affiliation(s)
- N Kalantari
- Cellular and Molecular Biology Research Center, Babol University of Medical Sciences; Laboratory Sciences Group, Faculty of Paramedical, Babol University of Medical Sciences, Babol, Iran,Corresponding author:
| | - S Ghaffari
- Parasitology and Mycology Group, Faculty of Medicine, Babol University of Medical Sciences, Babol, Iran
| |
Collapse
|
13
|
Pati SS, Mishra SK. Infectious disease: Pathogenesis of cerebral malaria-a step forward. Nat Rev Neurol 2012; 8:415-6. [PMID: 22825704 DOI: 10.1038/nrneurol.2012.144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Sudhanshu S Pati
- Department of Internal Medicine and Biochemistry, Ispat General Hospital, Orissa, India
| | | |
Collapse
|
14
|
Ghumra A, Semblat JP, Ataide R, Kifude C, Adams Y, Claessens A, Anong DN, Bull PC, Fennell C, Arman M, Amambua-Ngwa A, Walther M, Conway DJ, Kassambara L, Doumbo OK, Raza A, Rowe JA. Induction of strain-transcending antibodies against Group A PfEMP1 surface antigens from virulent malaria parasites. PLoS Pathog 2012; 8:e1002665. [PMID: 22532802 PMCID: PMC3330128 DOI: 10.1371/journal.ppat.1002665] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2011] [Accepted: 03/08/2012] [Indexed: 12/22/2022] Open
Abstract
Sequence diversity in pathogen antigens is an obstacle to the development of interventions against many infectious diseases. In malaria caused by Plasmodium falciparum, the PfEMP1 family of variant surface antigens encoded by var genes are adhesion molecules that play a pivotal role in malaria pathogenesis and clinical disease. PfEMP1 is a major target of protective immunity, however, development of drugs or vaccines based on PfEMP1 is problematic due to extensive sequence diversity within the PfEMP1 family. Here we identified the PfEMP1 variants transcribed by P. falciparum strains selected for a virulence-associated adhesion phenotype (IgM-positive rosetting). The parasites transcribed a subset of Group A PfEMP1 variants characterised by an unusual PfEMP1 architecture and a distinct N-terminal domain (either DBLα1.5 or DBLα1.8 type). Antibodies raised in rabbits against the N-terminal domains showed functional activity (surface reactivity with live infected erythrocytes (IEs), rosette inhibition and induction of phagocytosis of IEs) down to low concentrations (<10 µg/ml of total IgG) against homologous parasites. Furthermore, the antibodies showed broad cross-reactivity against heterologous parasite strains with the same rosetting phenotype, including clinical isolates from four sub-Saharan African countries that showed surface reactivity with either DBLα1.5 antibodies (variant HB3var6) or DBLα1.8 antibodies (variant TM284var1). These data show that parasites with a virulence-associated adhesion phenotype share IE surface epitopes that can be targeted by strain-transcending antibodies to PfEMP1. The existence of shared surface epitopes amongst functionally similar disease-associated P. falciparum parasite isolates suggests that development of therapeutic interventions to prevent severe malaria is a realistic goal. Malaria remains one of the world's most deadly diseases. Life-threatening malaria is linked to a process called rosetting, in which malaria parasite-infected red blood cells bind to uninfected red cells to form aggregates that block blood flow in vital organs such as the brain. Current efforts to develop drugs or vaccines against rosetting are hindered by variation in the parasite rosette-mediating proteins, found on the surface of infected red cells. We studied these parasite-derived surface proteins and discovered that although they are variable, they share some common features. We raised antibodies against the rosette-mediating proteins, and found that they cross-reacted with multiple rosetting parasite strains from different countries around the world, including samples collected directly from African children with severe malaria. These findings provide new insights into malaria parasite interactions with human cells, and provide proof of principle that variable parasite molecules from virulent malaria parasites can induce strain-transcending antibodies. Hence, this work provides the foundation for the development of new therapies to treat or prevent life-threatening malaria.
Collapse
Affiliation(s)
- Ashfaq Ghumra
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Jean-Philippe Semblat
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Ricardo Ataide
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Carolyne Kifude
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Yvonne Adams
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Antoine Claessens
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Damian N. Anong
- Biotechnology Unit, Faculty of Science, University of Buea, Buea, Cameroon
| | - Peter C. Bull
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Clare Fennell
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Monica Arman
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | | | - Michael Walther
- Medical Research Council Laboratories, Fajara, Banjul, The Gambia
| | - David J. Conway
- Medical Research Council Laboratories, Fajara, Banjul, The Gambia
| | - Lalla Kassambara
- Malaria Research and Training Centre, University of Bamako, Bamako, Mali
| | - Ogobara K. Doumbo
- Malaria Research and Training Centre, University of Bamako, Bamako, Mali
| | - Ahmed Raza
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - J. Alexandra Rowe
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
| |
Collapse
|
15
|
Johnson PLF, Kochin BF, Ahmed R, Antia R. How do antigenically varying pathogens avoid cross-reactive responses to invariant antigens? Proc Biol Sci 2012; 279:2777-85. [PMID: 22438498 DOI: 10.1098/rspb.2012.0005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Pathogens such as trypanosomes and malaria use antigenic variation to evade immune responses and prolong the duration of infections. As pathogens typically express more than one antigen, even relatively rare conserved antigens might be expected to trigger cross-reactive immune responses capable of clearing the infection. We use simple mathematical models that explicitly consider the dynamic interplay between the replicating pathogen, immune responses to different antigens and immune exhaustion to explore how pathogens can escape the responses to both variable and invariant (conserved) antigens. Our results suggest two hypotheses. In the first, limited quantities of invariant antigens on each pathogen may lead to saturation in killing by cross-reactive responses. In the second, antigenic variation of the dominant antigens prolongs the duration of infection sufficiently to allow for exhaustion of the cross-reactive responses to subdominant, invariant epitopes prior to their being able to control the infection. These hypotheses make distinct predictions: the former predicts that cross-reactive responses will always be ineffective while the latter predicts that appropriately timed treatment could, by preventing exhaustion, lead to the generation of long-lasting protective cross-reactive immunity and thus act similarly to a vaccine.
Collapse
|
16
|
Vigan-Womas I, Guillotte M, Juillerat A, Vallieres C, Lewit-Bentley A, Tall A, Baril L, Bentley GA, Mercereau-Puijalon O. Allelic diversity of the Plasmodium falciparum erythrocyte membrane protein 1 entails variant-specific red cell surface epitopes. PLoS One 2011; 6:e16544. [PMID: 21298021 PMCID: PMC3029348 DOI: 10.1371/journal.pone.0016544] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Accepted: 12/21/2010] [Indexed: 01/11/2023] Open
Abstract
The clonally variant Plasmodium falciparum PfEMP1 adhesin is a virulence factor and a prime target of humoral immunity. It is encoded by a repertoire of functionally differentiated var genes, which display architectural diversity and allelic polymorphism. Their serological relationship is key to understanding the evolutionary constraints on this gene family and rational vaccine design. Here, we investigated the Palo Alto/VarO and IT4/R29 and 3D7/PF13_003 parasites lines. VarO and R29 form rosettes with uninfected erythrocytes, a phenotype associated with severe malaria. They express an allelic Cys2/group A NTS-DBL1α1 PfEMP1 domain implicated in rosetting, whose 3D7 ortholog is encoded by PF13_0003. Using these three recombinant NTS-DBL1α1 domains, we elicited antibodies in mice that were used to develop monovariant cultures by panning selection. The 3D7/PF13_0003 parasites formed rosettes, revealing a correlation between sequence identity and virulence phenotype. The antibodies cross-reacted with the allelic domains in ELISA but only minimally with the Cys4/group B/C PFL1955w NTS-DBL1α. By contrast, they were variant-specific in surface seroreactivity of the monovariant-infected red cells by FACS analysis and in rosette-disruption assays. Thus, while ELISA can differentiate serogroups, surface reactivity assays define the more restrictive serotypes. Irrespective of cumulated exposure to infection, antibodies acquired by humans living in a malaria-endemic area also displayed a variant-specific surface reactivity. Although seroprevalence exceeded 90% for each rosetting line, the kinetics of acquistion of surface-reactive antibodies differed in the younger age groups. These data indicate that humans acquire an antibody repertoire to non-overlapping serotypes within a serogroup, consistent with an antibody-driven diversification pressure at the population level. In addition, the data provide important information for vaccine design, as production of a vaccine targeting rosetting PfEMP1 adhesins will require engineering to induce variant-transcending responses or combining multiple serotypes to elicit a broad spectrum of immunity.
Collapse
Affiliation(s)
- Inès Vigan-Womas
- Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, Paris, France
- CNRS URA 2581, Paris, France
| | - Micheline Guillotte
- Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, Paris, France
- CNRS URA 2581, Paris, France
| | - Alexandre Juillerat
- Institut Pasteur, Unité d'Immunologie Structurale, Paris, France
- CNRS URA 2185, Paris, France
| | - Cindy Vallieres
- Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, Paris, France
- CNRS URA 2581, Paris, France
| | - Anita Lewit-Bentley
- Institut Pasteur, Unité d'Immunologie Structurale, Paris, France
- CNRS URA 2185, Paris, France
| | - Adama Tall
- Unité d'Epidémiologie des Maladies Infectieuses, Institut Pasteur, Dakar, Sénégal
| | - Laurence Baril
- Unité d'Epidémiologie des Maladies Infectieuses, Institut Pasteur, Dakar, Sénégal
| | - Graham A. Bentley
- Institut Pasteur, Unité d'Immunologie Structurale, Paris, France
- CNRS URA 2185, Paris, France
| | - Odile Mercereau-Puijalon
- Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, Paris, France
- CNRS URA 2581, Paris, France
- * E-mail:
| |
Collapse
|
17
|
Functional and immunological characterization of a Duffy binding-like alpha domain from Plasmodium falciparum erythrocyte membrane protein 1 that mediates rosetting. Infect Immun 2009; 77:3857-63. [PMID: 19546191 DOI: 10.1128/iai.00049-09] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Duffy binding-like (DBL) domains are common adhesion modules present in Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) variants, which are responsible for immune evasion and cytoadherence. Knowledge about how immune responses are acquired against polymorphic DBL domains of PfEMP1 can aid in the development of vaccines for malaria. A recombinant DBLalpha domain, encoded by R29 var1, which binds complement receptor 1 to mediate rosetting by the P. falciparum laboratory strain R29, was expressed in Escherichia coli, renatured by oxidative refolding to its native form, and purified to homogeneity. Antibody levels in 704 plasmas obtained from residents of areas of different levels of malaria endemicity in Orissa (India) and Manhiça (Mozambique) were assessed by enzyme-linked immunosorbent assay. The refolded DBLalpha domain was pure, homogeneous, and functional in that it bound human erythrocytes with specificity and was capable of inhibiting rosetting. The proportion of individuals who had measurable anti-DBLalpha immunoglobulin G responses was low in areas of low malaria endemicity in Orissa (6.7%) but high in areas of high endemicity in Orissa (87.5%) and Manhiça (74.5%). Seroprevalence and antibody levels against the recombinant protein increased with the age of inhabitants from areas with high transmission rates (P < 0.001). Half of the children in these areas had seroconverted by the age of 5 years. These findings suggest that in spite of the extreme polymorphism of PfEMP1 DBLalpha domains, the acquisition of specific antibodies is rapid and age related and reflects the reduced risk of malaria in areas with high transmission rates. Further studies are required to elucidate the role of these antibodies in protection from malaria.
Collapse
|
18
|
Singh S, Soe S, Weisman S, Barnwell JW, Pérignon JL, Druilhe P. A conserved multi-gene family induces cross-reactive antibodies effective in defense against Plasmodium falciparum. PLoS One 2009; 4:e5410. [PMID: 19404387 PMCID: PMC2671155 DOI: 10.1371/journal.pone.0005410] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2008] [Accepted: 03/23/2009] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Two related merozoite surface proteins, MSP3 and MSP6, have previously been identified as targets of antibody-dependent cellular inhibition (ADCI), a protective mechanism against Plasmodium falciparum malaria. Both MSP3 and MSP6 share a common characteristic small N-terminal signature amino-acid stretch (NLRNA/G), a feature similar to MSP3-like orthologs identified in other human and primate malaria parasites. METHODS/RESULTS This signature amino-acid sequence led to the identification of eight ORFs contiguously located on P. falciparum chromosome 10. Our subsequent investigations on their expression, localization, sequence conservation, epitope sharing, immunogenicity and the functional role of antibodies in defense are reported here. Six members of P. falciparum MSP3-multigene family share similar sequence organization within their C-terminal regions, are simultaneously expressed as merozoite surface proteins and are highly conserved among parasite isolates. Each of these proteins is a target of naturally occurring antibodies effective at parasite killing in ADCI assays. Moreover, both naturally occurring antibodies and those generated by immunization display cross-reactivity with other members of the family and exhibit varied binding avidities. CONCLUSIONS/SIGNIFICANCE The unusual characteristics of the MSP3 multi-gene family lead us to hypothesize that the simultaneous expression of targets eliciting cross-reactive antibody responses capable of controlling parasite densities could represent an immune process selected through evolution to maintain homeostasis between P. falciparum and human hosts; a process that allows the continuous transmission of the parasite without killing the host. Our observations also have practical consequences for vaccine development by suggesting MSP3 vaccine efficacy might be improved when combined with the various C-terminus regions of the MSP3 family members to generate a wider range of antibodies acting and to increase vaccine immunogenicity in varied human genetic backgrounds.
Collapse
Affiliation(s)
- Subhash Singh
- Bio-medical Parasitology Unit, Institut Pasteur, Paris, France
- * E-mail: (SS); (PD)
| | - Soe Soe
- Bio-medical Parasitology Unit, Institut Pasteur, Paris, France
| | - Simon Weisman
- Bio-medical Parasitology Unit, Institut Pasteur, Paris, France
| | - John W. Barnwell
- Malaria Branch, Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | | | - Pierre Druilhe
- Bio-medical Parasitology Unit, Institut Pasteur, Paris, France
- * E-mail: (SS); (PD)
| |
Collapse
|
19
|
Buckee CO, Bull PC, Gupta S. Inferring malaria parasite population structure from serological networks. Proc Biol Sci 2009; 276:477-85. [PMID: 18826933 PMCID: PMC2581777 DOI: 10.1098/rspb.2008.1122] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The malaria parasite Plasmodium falciparum is characterized by high levels of genetic diversity at antigenic loci involved in virulence and immune evasion. Knowledge of the population structure and dynamics of these genes is important for designing control programmes and understanding the acquisition of immunity to malaria; however, high rates of homologous and non-homologous recombination as well as complex patterns of expression within hosts have hindered attempts to elucidate these structures experimentally. Here, we analyse serological data from Kenya using a novel network technique to deconstruct the relationships between patients' immune responses to different parasite isolates. We show that particular population structures and expression patterns produce distinctive signatures within serological networks of parasite recognition, which can be used to discriminate between competing hypotheses regarding the organization of these genes. Our analysis suggests that different levels of immune selection occur within different groups of the same multigene family leading to mixed population structures.
Collapse
Affiliation(s)
- Caroline O Buckee
- Department of Zoology, University of Oxford, Tinbergen Building, South Parks Road, Oxford OX1 3PS, UK.
| | | | | |
Collapse
|
20
|
Abstract
Naturally acquired immunity to falciparum malaria protects millions of people routinely exposed to Plasmodium falciparum infection from severe disease and death. There is no clear concept about how this protection works. There is no general agreement about the rate of onset of acquired immunity or what constitutes the key determinants of protection; much less is there a consensus regarding the mechanism(s) of protection. This review summarizes what is understood about naturally acquired and experimentally induced immunity against malaria with the help of evolving insights provided by biotechnology and places these insights in the context of historical, clinical, and epidemiological observations. We advocate that naturally acquired immunity should be appreciated as being virtually 100% effective against severe disease and death among heavily exposed adults. Even the immunity that occurs in exposed infants may exceed 90% effectiveness. The induction of an adult-like immune status among high-risk infants in sub-Saharan Africa would greatly diminish disease and death caused by P. falciparum. The mechanism of naturally acquired immunity that occurs among adults living in areas of hyper- to holoendemicity should be understood with a view toward duplicating such protection in infants and young children in areas of endemicity.
Collapse
Affiliation(s)
- Denise L Doolan
- Queensland Institute of Medical Research, The Bancroft Centre, Post Office Royal Brisbane Hospital, Brisbane, Queensland 4029, Australia.
| | | | | |
Collapse
|
21
|
Ozarkar A, Prakash D, Deobagkar D, Deobagkar D. Analysis of PfEMP1—var Gene Sequences in Different Plasmodium falciparum Malarial Parasites. ACTA ACUST UNITED AC 2009. [DOI: 10.3814/2009/824949] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
22
|
Mackintosh CL, Christodoulou Z, Mwangi TW, Kortok M, Pinches R, Williams TN, Marsh K, Newbold CI. Acquisition of naturally occurring antibody responses to recombinant protein domains of Plasmodium falciparum erythrocyte membrane protein 1. Malar J 2008; 7:155. [PMID: 18706102 PMCID: PMC2533674 DOI: 10.1186/1475-2875-7-155] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2008] [Accepted: 08/16/2008] [Indexed: 11/21/2022] Open
Abstract
Background Antibodies targeting variant antigens expressed on the surface of Plasmodium falciparum infected erythrocytes have been associated with protection from clinical malaria. The precise target for these antibodies is unknown. The best characterized and most likely target is the erythrocyte surface-expressed variant protein family Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). Methods Using recombinant proteins corresponding to five domains of the expressed A4 var gene, A4 PfEMP1, the naturally occurring antibody response was assessed, by ELISA, to each domain in serum samples obtained from individuals resident in two communities of differing malaria transmission intensity on the Kenyan coast. Using flow cytometry, the correlation in individual responses to each domain with responses to intact A4-infected erythrocytes expressing A4 PfEMP1 on their surface as well as responses to two alternative parasite clones and one clinical isolate was assessed. Results Marked variability in the prevalence of responses between each domain and between each transmission area was observed, as wasa strong correlation between age and reactivity with some but not all domains. Individual responses to each domain varied strikingly, with some individuals showing reactivity to all domains and others with no reactivity to any, this was apparent at all age groups. Evidence for possible cross-reactivity in responses to the domain DBL4γ was found. Conclusion Individuals acquire antibodies to surface expressed domains of a highly variant protein. The finding of potential cross-reactivity in responses to one of these domains is an important initial finding in the consideration of potential vaccine targets.
Collapse
Affiliation(s)
- Claire L Mackintosh
- Kenya Medical Research Institute Centre for Geographic Medicine Research Coast, Kilifi District Hospital, Kilifi, Kenya.
| | | | | | | | | | | | | | | |
Collapse
|
23
|
Mackintosh CL, Mwangi T, Kinyanjui SM, Mosobo M, Pinches R, Williams TN, Newbold CI, Marsh K. Failure to respond to the surface of Plasmodium falciparum infected erythrocytes predicts susceptibility to clinical malaria amongst African children. Int J Parasitol 2008; 38:1445-54. [PMID: 18534600 PMCID: PMC2697313 DOI: 10.1016/j.ijpara.2008.03.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2008] [Revised: 03/07/2008] [Accepted: 03/17/2008] [Indexed: 11/15/2022]
Abstract
Following infection with Plasmodium falciparum malaria, children in endemic areas develop antibodies specific to antigens on the parasite-infected red cell surface of the infecting isolate, antibodies associated with protection against subsequent infection with that isolate. In some circumstances induction of antibodies to heterologous parasite isolates also occurs and this has been suggested as evidence for cross-reactivity of responses against the erythrocyte surface. The role of these relatively cross-reactive antibodies in protection from clinical malaria is currently unknown. We studied the incidence of clinical malaria amongst children living on the coast of Kenya through one high transmission season. By categorising individuals according to their pre-season parasite status and antibody response to the surface of erythrocytes infected with four parasite isolates we were able to identify a group of children, those who failed to make a concomitant antibody response in the presence of an asymptomatic parasitaemia, at increased susceptibility to clinical malaria in the subsequent 6 months. The fact that this susceptible group was identified regardless of the parasite isolate tested infers a cross-reactive or conserved target is present on the surface of infected erythrocytes. Identification of this target will significantly aid understanding of naturally acquired immunity to clinical malaria amongst children in endemic areas.
Collapse
Affiliation(s)
- C L Mackintosh
- Kenya Medical Research Institute, Centre for Geographic Medicine Research Coast, Kilifi District Hospital, Kilifi, Kenya.
| | | | | | | | | | | | | | | |
Collapse
|
24
|
Recker M, Arinaminpathy N, Buckee CO. The effects of a partitioned var gene repertoire of Plasmodium falciparum on antigenic diversity and the acquisition of clinical immunity. Malar J 2008; 7:18. [PMID: 18215289 PMCID: PMC2265724 DOI: 10.1186/1475-2875-7-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Accepted: 01/23/2008] [Indexed: 12/04/2022] Open
Abstract
Background The human malaria parasite Plasmodium falciparum exploits antigenic diversity and within-host antigenic variation to evade the host's immune system. Of particular importance are the highly polymorphic var genes that encode the family of cell surface antigens PfEMP1 (Plasmodium falciparum Erythrocyte Membrane Protein 1). It has recently been shown that in spite of their extreme diversity, however, these genes fall into distinct groups according to chromosomal location or sequence similarity, and that recombination may be confined within these groups. Methods This study presents a mathematical analysis of how recombination hierarchies affect diversity, and, by using simple stochastic simulations, investigates how intra- and inter-genic diversity influence the rate at which individuals acquire clinical immunity. Results The analysis demonstrates that the partitioning of the var gene repertoire has a limiting effect on the total diversity attainable through recombination and that the limiting effect is strongly influenced by the respective sizes of each of the partitions. Furthermore, by associating expression of one of the groups with severe malaria it is demonstrated how a small number of infections can be sufficient to protect against disease despite a seemingly limitless number of possible non-identical repertoires. Conclusion Recombination hierarchies within the var gene repertoire of P. falciparum have a severe effect on strain diversity and the process of acquiring immunity against clinical malaria. Future studies will show how the existence of these recombining groups can offer an evolutionary advantage in spite of their restriction on diversity.
Collapse
Affiliation(s)
- Mario Recker
- Department of Zoology, South Parks Road, OX1 3PS, Oxford, UK.
| | | | | |
Collapse
|
25
|
Chookajorn T, Costanzo MS, Hartl DL, Deitsch KW. Malaria: a peek at the var variorum. Trends Parasitol 2007; 23:563-5. [DOI: 10.1016/j.pt.2007.08.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 08/21/2007] [Accepted: 08/21/2007] [Indexed: 11/25/2022]
|
26
|
Kyes SA, Kraemer SM, Smith JD. Antigenic variation in Plasmodium falciparum: gene organization and regulation of the var multigene family. EUKARYOTIC CELL 2007; 6:1511-20. [PMID: 17644655 PMCID: PMC2043368 DOI: 10.1128/ec.00173-07] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Sue A Kyes
- Molecular Parasitology Group, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom
| | | | | |
Collapse
|
27
|
Ma SH, Zheng L, Liu YJ, Guo SY, Feng H, Chen G, Li DM, Wang JC, Cao YM. Plasmodium yoelii: Influence of antimalarial treatment on acquisition of immunity in BALB/c and DBA/2 mice. Exp Parasitol 2007; 116:266-72. [PMID: 17336298 DOI: 10.1016/j.exppara.2007.01.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Revised: 12/22/2006] [Accepted: 01/12/2007] [Indexed: 11/19/2022]
Abstract
The effect of antimalarial drugs on immune responses to the malaria infection is evaluated in vivo using two experimental self-cured rodent models. BALB/c and DBA/2 mice were infected by Plasmodium yoelii 17XNL and 17XL strains, respectively, and then treated with different doses of antimalarial drugs: chloroquine (228mg/kg or 114mg/kg of the body weight) or artesunate (78mg/kg or 39mg/kg). The effect of antimalarial drugs on host immune responses was evaluated by parasitemia, splenocyte IFN-gamma production level, and parasite-specific IgG level in the serum, however, no significant differences were observed between drug-treated and untreated groups. Moreover, most of the infected mice of all groups showed the ability to resist homologous reinfection (challenged on day 60 post-infection), only a few mice experienced transient, low parasitemia. The rechallenged mice were accompanied by high level of parasite-specific IgG. Therefore, this research implicated that, for BALB/c and DBA/2 mice, chloroquine or artesunate treatment of blood-stage P. yoelii infections does not compromise acquired immunity to malaria in either primary infection or upon rechallenge.
Collapse
Affiliation(s)
- Shi-Hong Ma
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Heping District, Shenyang, China
| | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Tippett E, Fernandes LA, Rogerson SJ, Jaworowski A. A novel flow cytometric phagocytosis assay of malaria-infected erythrocytes. J Immunol Methods 2007; 325:42-50. [PMID: 17658546 DOI: 10.1016/j.jim.2007.05.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2006] [Revised: 05/18/2007] [Accepted: 05/18/2007] [Indexed: 11/19/2022]
Abstract
Monocytes play a crucial role in controlling malaria infection. To facilitate our research into the development of antibody-mediated immunity against pregnancy-associated malaria we have established several novel malaria-specific flow cytometric phagocytosis assays based on ethidium bromide staining of DNA present in blood stage trophozoites. The first assay quantifies the ability of sera to opsonise trophozoites and promotes phagocytosis by the monocytic cell line THP1. This measures the levels of functional antibodies to the chosen strain of parasite. The second assay is a whole blood phagocytosis assay which measures the phagocytic ability of patient monocytes ex vivo. The third assay employs simultaneous labelling of trophozoites with ethidium bromide and erythrocytes with fluorescein isothiocyanate to compare phagocytosis of both non-infected and parasitised erythrocytes to assess possible bystander effects on uninfected erythrocytes. These assays have the advantage over other malaria phagocytosis assays in that they are rapid, simple and specific to malaria-infected cells and avoid potential bias associated with manual counting.
Collapse
Affiliation(s)
- Emma Tippett
- AIDS Pathogenesis and Clinical Research Program, Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Australia.
| | | | | | | |
Collapse
|
29
|
Barry AE, Leliwa-Sytek A, Tavul L, Imrie H, Migot-Nabias F, Brown SM, McVean GAV, Day KP. Population genomics of the immune evasion (var) genes of Plasmodium falciparum. PLoS Pathog 2007; 3:e34. [PMID: 17367208 PMCID: PMC1828697 DOI: 10.1371/journal.ppat.0030034] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2006] [Accepted: 01/24/2007] [Indexed: 12/01/2022] Open
Abstract
Var genes encode the major surface antigen (PfEMP1) of the blood stages of the human malaria parasite Plasmodium falciparum. Differential expression of up to 60 diverse var genes in each parasite genome underlies immune evasion. We compared the diversity of the DBLα domain of var genes sampled from 30 parasite isolates from a malaria endemic area of Papua New Guinea (PNG) and 59 from widespread geographic origins (global). Overall, we obtained over 8,000 quality-controlled DBLα sequences. Within our sampling frame, the global population had a total of 895 distinct DBLα “types” and negligible overlap among repertoires. This indicated that var gene diversity on a global scale is so immense that many genomes would need to be sequenced to capture its true extent. In contrast, we found a much lower diversity in PNG of 185 DBLα types, with an average of approximately 7% overlap among repertoires. While we identify marked geographic structuring, nearly 40% of types identified in PNG were also found in samples from different countries showing a cosmopolitan distribution for much of the diversity. We also present evidence to suggest that recombination plays a key role in maintaining the unprecedented levels of polymorphism found in these immune evasion genes. This population genomic framework provides a cost effective molecular epidemiological tool to rapidly explore the geographic diversity of var genes. Malaria parasites live in red blood cells of the human host for part of the life cycle, during which a family of diverse antigens known as PfEMP1 are placed on the surface. PfEMP1 variants switch by sequential expression of up to 60 var genes. This allows the parasite to evade immune detection within an individual host, enhancing its chances to be transmitted to the mosquito vector in situations where mosquitoes are seasonally available. Methods to rapidly assess var gene diversity in parasite populations are needed to measure antigenic diversity and define relationships with malaria transmission. Using a specialized framework, we completed the first systematic sampling of var genes from parasite genomes obtained from the same (Papua New Guinea [PNG]) and different (global) populations. Globally, there was no limit to the number of var genes because parasites rarely shared var genes. In PNG, var gene numbers were restricted due to high levels of sharing, and most were only found in that population. Recombination was important to the evolution of var genes in PNG. The data suggest there are distinct var genes in different populations, which may have consequences for the spread of malarial disease from one geographic area to another.
Collapse
Affiliation(s)
- Alyssa E Barry
- Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, United Kingdom
- Department of Zoology, University of Oxford, Oxford, United Kingdom
- * To whom correspondence should be addressed. E-mail:
| | - Aleksandra Leliwa-Sytek
- Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, United Kingdom
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Livingston Tavul
- Papua New Guinea Institute for Medical Research, Madang, Papua New Guinea
| | - Heather Imrie
- Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, United Kingdom
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Florence Migot-Nabias
- Centre International de Recherches Médicales de Franceville (CIRMF), Franceville, Gabon
| | - Stuart M Brown
- Research Computing Resource, New York University School of Medicine, New York, New York, United States of America
| | | | - Karen P Day
- Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, United Kingdom
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| |
Collapse
|
30
|
Pati SS, Mishra S, Mohanty S, Mohapatra DN, Sahu PK, Priyadarshi N, Kumar S, Sharma SK, Tyagi PK, Chitnis CE, Das BS. Pfcrt haplotypes and in-vivo chloroquine response in Sundergarh district, Orissa, India. Trans R Soc Trop Med Hyg 2007; 101:650-4. [PMID: 17428514 DOI: 10.1016/j.trstmh.2007.01.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2006] [Revised: 01/30/2007] [Accepted: 01/30/2007] [Indexed: 11/17/2022] Open
Abstract
The Plasmodium falciparum chloroquine resistance transporter (Pfcrt) K76T mutation and haplotype (amino acids 72-76) were analyzed as markers of chloroquine (CQ) resistance in the blood samples of patients from two sites of different intensities of malaria transmission (high, n=70; low, n=68) in Sundergarh district of Orissa, India and correlated with the in-vivo response. Early treatment failure (ETF) was significantly more frequent in the high endemic area (32.9 vs. 7.4%, P<0.001), with children below 5 years suffering more. A high frequency of pfcrt K76T mutation was observed in both the areas (87.1 vs. 79.4%, P=0.22). Patients carrying pfcrt 76T were the most likely to develop ETF (odds ratio 36; 95% CI 3.35-1653.3; P<0.001). The ratio of 76T:K76 was 22:9 and 11:14, respectively, in high and low endemic areas (odds ratio 3.1; 95% CI 0.9-11.03; P=0.04), which may be used as a measure of drug pressure. Sequences of pfcrt codons 72-76 showed 16 of the CQ-resistant haplotypes to be SVMNT, 5 CVMNT and 12 CVIET. The CQ-sensitive haplotypes were mostly CVMNK in 10 samples; CVIEK in 2 samples. Both Southeast Asian and South American haplotypes were present, with the latter predominating.
Collapse
Affiliation(s)
- Sudhanshu S Pati
- Department of Biochemistry and Molecular Biology, Ispat General Hospital, Rourkela-769005, Orissa, India.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Moll K, Pettersson F, Vogt AM, Jonsson C, Rasti N, Ahuja S, Spångberg M, Mercereau-Puijalon O, Arnot DE, Wahlgren M, Chen Q. Generation of cross-protective antibodies against Plasmodium falciparum sequestration by immunization with an erythrocyte membrane protein 1-duffy binding-like 1 alpha domain. Infect Immun 2006; 75:211-9. [PMID: 17074852 PMCID: PMC1828381 DOI: 10.1128/iai.00749-06] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) is an important virulence factor on the surface of infected erythrocytes. Naturally acquired antibodies to PfEMP1 expressed by parasites causing severe malaria are suggested to be protective and of major interest for the development of a vaccine against severe disease. In this study, the PfEMP1 expressed by a parasite clone displaying a multiadhesive phenotype associated with severe malaria was well recognized by sera of malaria semi-immune children. The efficiency of the Duffy binding-like 1 alpha (DBL1 alpha) domain of this PfEMP1 was therefore, alone or in combination with two additional DBL1 alpha domains, evaluated as a potential vaccine candidate using both a rodent model and a primate model. Antibodies against the DBL1 alpha domain were generated by immunization with recombinant DBL1 alpha-Semliki Forest virus particles and recombinant protein and analyzed in vitro. The immunized animals were challenged in vivo with various parasite strains or clones. Immunization with the PfEMP1-DBL1 alpha domain abolished the PfEMP1-dependent sequestration of the homologous strain in immunized rats and substantially inhibited parasite adhesion in immunized monkeys. Protection against sequestration of heterologous parasite strains was also confirmed by direct or indirect challenge in the rat model. These results strongly support the use of the DBL1 alpha domain in the development of a vaccine targeting severe malaria.
Collapse
Affiliation(s)
- Kirsten Moll
- Microbiology and Tumorbiology Center, Karolinska Institutet and Swedish Institute for Infectious Disease Control, Nobels väg 16, 171 77 Stockholm, Sweden
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Oliveira TR, Fernandez-Becerra C, Jimenez MCS, Del Portillo HA, Soares IS. Evaluation of the acquired immune responses to Plasmodium vivax VIR variant antigens in individuals living in malaria-endemic areas of Brazil. Malar J 2006; 5:83. [PMID: 17026752 PMCID: PMC1626480 DOI: 10.1186/1475-2875-5-83] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2006] [Accepted: 10/06/2006] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The naturally-acquired immune response to Plasmodium vivax variant antigens (VIR) was evaluated in individuals exposed to malaria and living in different endemic areas for malaria in the north of Brazil. METHODS Seven recombinant proteins representing four vir subfamilies (A, B, C, and E) obtained from a single patient from the Amazon Region were expressed in Escherichia coli as soluble glutathione S-transferase fusion proteins. The different recombinant proteins were compared by ELISA with regard to the recognition by IgM, IgG, and IgG subclass of antibodies from 200 individuals with patent infection. RESULTS The frequency of individuals that presented antibodies anti-VIR (IgM plus IgG) during the infection was 49%. The frequencies of individuals that presented IgM or IgG antibodies anti-VIR were 29.6% or 26.0%, respectively. The prevalence of IgG antibodies against recombinant VIR proteins was significantly lower than the prevalence of antibodies against the recombinant proteins representing two surface antigens of merozoites of P. vivax: AMA-1 and MSP119 (57.0% and 90.5%, respectively). The cellular immune response to VIR antigens was evaluated by in vitro proliferative assays in mononuclear cells of the individuals recently exposed to P. vivax. No significant proliferative response to these antigens was observed when comparing malaria-exposed to non-exposed individuals. CONCLUSION This study provides evidence that there is a low frequency of individuals responding to each VIR antigens in endemic areas of Brazil. This fact may explain the host susceptibility to new episodes of the disease.
Collapse
Affiliation(s)
- Tatiane R Oliveira
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Av. Prof. Lineu Prestes, 580, 05508-900, São Paulo, SP, Brazil
| | - Carmen Fernandez-Becerra
- Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes, 1374, 05508-900, São Paulo, SP, Brazil
| | - Maria Carolina S Jimenez
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Av. Prof. Lineu Prestes, 580, 05508-900, São Paulo, SP, Brazil
| | - Hernando A Del Portillo
- Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes, 1374, 05508-900, São Paulo, SP, Brazil
| | - Irene S Soares
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Av. Prof. Lineu Prestes, 580, 05508-900, São Paulo, SP, Brazil
| |
Collapse
|
33
|
Ahuja S, Pettersson F, Moll K, Jonsson C, Wahlgren M, Chen Q. Induction of cross-reactive immune responses to NTS-DBL-1alpha/x of PfEMP1 and in vivo protection on challenge with Plasmodium falciparum. Vaccine 2006; 24:6140-54. [PMID: 16837110 DOI: 10.1016/j.vaccine.2006.05.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2005] [Revised: 04/28/2006] [Accepted: 05/09/2006] [Indexed: 10/24/2022]
Abstract
The interactions of Plasmodium falciparum infected erythrocytes parasitized red blood cells (pRBC) with endothelial receptors and erythrocytes are mediated by multiple Duffy-binding like (DBL) and cysteine-rich interdomain region (CIDR) domains harboured in the Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). The success of a subunit vaccine based on PfEMP1 depends on its ability to elicit cross-reactive responses to a substantial number of PfEMP1 variants. We have here evaluated serological PfEMP1 cross-reactivity by immunizing rats with phylogenetically diverse recombinant NTS-DBL-1alpha/x fusion domains from the 3D7 genome parasite emulsified in Montanide ISA 720. Cross-reactivity was elicited to these diverse DBL-1alpha/x domains as measured by ELISA and by immunoblotting. Employing a novel in vivo model of human infected erythrocyte sequestration, immunized animals were challenged with the FCR3S1.2 clone and cross-protection in terms of reduction in lung sequestration amounting to approximately 50% was demonstrated. Our results suggest that immunization with phylogenetically distant DBL-1alpha/x variants, can elicit partial cross-protection to challenge with the parasites harbouring a distant variant. These observations have implications for the design of multi-component vaccines against P. falciparum malaria.
Collapse
Affiliation(s)
- Sanjay Ahuja
- Microbiology and Tumor Biology Center (MTC), Karolinska Institute, P.O. Box 280, SE-17177 Stockholm, Sweden
| | | | | | | | | | | |
Collapse
|
34
|
Sharma SK, Tyagi PK, Padhan K, Upadhyay AK, Haque MA, Nanda N, Joshi H, Biswas S, Adak T, Das BS, Chauhan VS, Chitnis CE, Subbarao SK. Epidemiology of malaria transmission in forest and plain ecotype villages in Sundargarh District, Orissa, India. Trans R Soc Trop Med Hyg 2006; 100:917-25. [PMID: 16697022 DOI: 10.1016/j.trstmh.2006.01.007] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2005] [Revised: 01/05/2006] [Accepted: 01/05/2006] [Indexed: 11/19/2022] Open
Abstract
A study of the epidemiology of malaria transmission was undertaken in 13 tribal villages located in forest and plain areas of Sundargarh District of Orissa state, India, from January 2001 to December 2003. In forest areas, intense transmission of malaria is attributed to the highly anthropophagic vector Anopheles fluviatilis sibling species S and is complemented by A. culicifacies sibling species C. In plain areas, A. culicifacies sibling species C is responsible for malaria transmission. The entomological inoculation rate in the forest and plain areas was 0.311 and 0.014 infective bites/person/night, respectively, during 2003. Malaria transmission is perennial both in forest and plain areas but is markedly low in the plain area compared with the forest area. Plasmodium falciparum accounted for 85.0% of the total malaria cases during the study period. In forest and plain areas, the number of P. falciparum cases per 1000 population per year was 284.1 and 31.2, respectively, whereas the parasite rate was 14.0% and 1.7%, respectively. In forest areas, clinical malaria occurs more frequently in children aged 0-5 years and declines gradually with increasing age. The study showed that villages in forest and plain areas separated by short geographical distances have distinct epidemiology of malaria transmission.
Collapse
Affiliation(s)
- Surya K Sharma
- National Institute of Malaria Research (formerly Malaria Research Centre), Field Station, Sector-5, Rourkela 769002, District Sundargarh, Orissa, India.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Schreiber N, Brattig N, Evans J, Horstmann RD, May J, Klinkert MQ. Cerebral malaria is associated with IgG2 and IgG4 antibody responses to recombinant Plasmodium falciparum RIFIN antigen. Microbes Infect 2006; 8:1269-76. [PMID: 16679041 DOI: 10.1016/j.micinf.2005.12.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2005] [Revised: 12/07/2005] [Accepted: 12/08/2005] [Indexed: 11/22/2022]
Abstract
RIFIN proteins belong to the largest Plasmodium falciparum multicopy family of variant surface antigens (VSA) expressed by infected erythrocytes. VSA antibodies have been shown to be associated with protection against malaria. Here, antibody subclass responses to a recombinant RIFIN protein (RIF-29) in 116 Ghanaian children were determined by ELISA to investigate the relationship between severe malaria and anti-RIF-29 antibodies. The study group was composed of 23 children diagnosed exclusively for cerebral malaria and 35 children who had non-cerebral severe malaria. The remaining 58 individuals were age-, gender- and area-matched asymptomatic controls. The finding that IgG1 and IgG3 responses predominated in severe malaria patients compared to matched controls suggests that these antibodies are not protective, but are most probably induced by a current infection, an observation substantiated by the equally high reactivity to both recombinant RIF-29 protein and to P. falciparum crude lysate proteins. The exclusive detection of IgG2 and IgG4 antibodies to RIF-29 protein only in cerebral malaria children brings to mind the possibility that these antibodies are pathogenic. This is a new finding that may go some way towards explaining why these children are at risk of developing the life-threatening form of cerebral malaria.
Collapse
MESH Headings
- Animals
- Antibodies, Protozoan/blood
- Antigens, Protozoan/genetics
- Antigens, Protozoan/immunology
- Case-Control Studies
- Child
- Child, Preschool
- Enzyme-Linked Immunosorbent Assay
- Humans
- Immunoglobulin G/blood
- Immunoglobulin Isotypes/blood
- Malaria, Cerebral/immunology
- Malaria, Cerebral/parasitology
- Malaria, Cerebral/physiopathology
- Malaria, Falciparum/immunology
- Malaria, Falciparum/parasitology
- Malaria, Falciparum/physiopathology
- Plasmodium falciparum/immunology
- Protozoan Proteins/genetics
- Protozoan Proteins/immunology
- Recombinant Proteins/genetics
- Recombinant Proteins/immunology
Collapse
Affiliation(s)
- Nadine Schreiber
- Bernhard-Nocht Institute for Tropical Medicine, Bernhard-Nocht-Strasse 74, 20359 Hamburg, Germany
| | | | | | | | | | | |
Collapse
|
36
|
Beeson JG, Mann EJ, Byrne TJ, Caragounis A, Elliott SR, Brown GV, Rogerson SJ. Antigenic differences and conservation among placental Plasmodium falciparum-infected erythrocytes and acquisition of variant-specific and cross-reactive antibodies. J Infect Dis 2006; 193:721-30. [PMID: 16453269 PMCID: PMC2483301 DOI: 10.1086/500145] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2005] [Accepted: 09/21/2005] [Indexed: 11/04/2022] Open
Abstract
Background. Pregnant women are infected by Plasmodium falciparum with novel antigenic phenotypes that adhere to chondroitin sulfate A (CSA) and other receptors in the placenta. The diverse and variant parasite protein P. falciparum erythrocyte membrane protein 1 (PfEMP1), which is encoded by var genes, is a ligand for CSA and a major target of antibodies associated with protective immunity.Methods. Serum samples from pregnant women exposed to malaria were tested for immunoglobulin G, adhesion-inhibitory antibodies, and agglutinating antibodies to different CSA-binding isolates expressing conserved var2csa-type genes and to parasite isolates from infected placentas. Parasite isolates also were examined to assess PfEMP1 expression, the effect of trypsin treatment of infected erythrocytes on parasite adhesion and cleavage of PfEMP1, and inhibition of adhesion by rabbit antiserum raised against a CSA-binding isolate.Results. Findings demonstrated that (1) there are significant antigenic differences between CSA-binding isolates that correspond with polymorphisms in var2csa; (2) there are differences in the properties of PfEMP1 and antibody reactivity between CSA-binding and placental isolates, which express multiple PfEMP1 forms; (3) acquired antibodies target diverse and cross-reactive epitopes expressed by CSA-binding infected erythrocytes, and cross-reactive antibodies are not necessarily cross-inhibitory; and (4) the breadth of antibody reactivity is greater among multigravidae than among primigravidae.Conclusions. Immunity may be mediated by a repertoire of antibodies to diverse and common epitopes. Strategies based on vaccination with a single domain or isolate might be hindered by antigenic diversity.
Collapse
Affiliation(s)
- James G Beeson
- Walter and Eliza Hall Institute of Medical Research, Parkville, and Department of Medicine, University of Melbourne, Royal Melbourne Hospital, Melbourne, Victoria, Australia.
| | | | | | | | | | | | | |
Collapse
|
37
|
Urban BC, Ing R, Stevenson MM. Early interactions between blood-stage plasmodium parasites and the immune system. Curr Top Microbiol Immunol 2005; 297:25-70. [PMID: 16265902 DOI: 10.1007/3-540-29967-x_2] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Accumulating evidence provides strong support for the importance of innate immunity in shaping the subsequent adaptive immune response to blood-stage Plasmodium parasites, the causative agents of malaria. Early interactions between blood-stage parasites and cells of the innate immune system, including dendritic cells, monocytes/macrophages, natural killer (NK) cells, NKT cells, and gamma6 T cells, are important in the timely control of parasite replication and in the subsequent elimination and resolution of the infection. The major role of innate immunity appears to be the production of immunoregulatory cytokines, such as interleukin (IL)-12 and interferon (IFN)-gamma, which are critical for the development of type 1 immune responses involving CD4+ Thl cells, B cells, and effector cells which mediate cell-mediated and antibody-dependent adaptive immune responses. In addition, it is likely that cells of the innate immune system, especially dendritic cells, serve as antigen-presenting cells. Here, we review recent data from rodent models of blood-stage malaria and from human studies, and outline the early interactions of infected red blood cells with the innate immune system. We compare and contrast the results derived from studies in infected laboratory mice and humans. These host species are sufficiently different with respect to the identity of the infecting Plasmodium species, the resulting pathologies, and immune responses, particularly where the innate immune response is concerned. The implications of these findings for the development of an effective and safe malaria vaccine are also discussed.
Collapse
Affiliation(s)
- B C Urban
- Centre for Clinical Vaccinology and Tropical Medicine, Nuffield Department of Clinical Medicine, Oxford University, Churchill Hospital, Old Road, Oxford, UK.
| | | | | |
Collapse
|
38
|
Gupta S. Parasite immune escape: new views into host-parasite interactions. Curr Opin Microbiol 2005; 8:428-33. [PMID: 15993644 DOI: 10.1016/j.mib.2005.06.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Accepted: 06/21/2005] [Indexed: 11/25/2022]
Abstract
For parasites of humans and animals that rely on vectors or on sexual contact for transmission, it is particularly important that infection does not to terminate before the occurrence of the crucial event that completes its lifecycle (e.g. another mosquito bite). For chronic infection to occur, it is essential that the parasite avoids clearance by the host immune system. Much progress has been made in elucidating the immunological interactions and the molecular mechanisms involved in the process of immune evasion. Mathematical models have also been invaluable in understanding these processes, particularly in the generation of new ideas about a complex form of immune evasion known as antigenic variation whereby a major target of the host immune response is varied during the course of a single infection to avoid recognition.
Collapse
Affiliation(s)
- Sunetra Gupta
- Department of Zoology, University of Oxford, Oxford, OX1 3PS, United Kingdom.
| |
Collapse
|
39
|
Yone CLRP, Kremsner PG, Luty AJF. Immunoglobulin G isotype responses to erythrocyte surface-expressed variant antigens of Plasmodium falciparum predict protection from malaria in African children. Infect Immun 2005; 73:2281-7. [PMID: 15784572 PMCID: PMC1087392 DOI: 10.1128/iai.73.4.2281-2287.2005] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We assessed immunoglobulin G (IgG) isotype responses to variant surface antigens (VSA) expressed on parasite-infected erythrocytes of a panel of heterologous isolates during and after acute episodes in groups of Gabonese children presenting with either mild or severe Plasmodium falciparum malaria. In the acute and convalescent phases IgG3 and IgG1 anti-VSA antibodies, respectively, predominated. In the absence of infection, the levels of both cytophilic isotypes waned, while those of IgG4 increased, particularly in those admitted with severe malaria. Prospective analyses showed significantly longer delays between malaria attacks associated both (i) with increasing IgG1 responses with specificity for VSA of isolates from children with mild malaria and (ii) with increasing IgG4 responses with specificity for VSA of isolates from children with severe malaria. These findings imply that the predictive value of prospectively measured cross-reactive VSA-specific IgG antibodies with respect to protection against malaria in African children depends both on their isotype and on their fine specificity.
Collapse
Affiliation(s)
- Clarisse L R P Yone
- Department of Parasitology, Institute of Tropical Medicine, Univeristy of Tübingen, Germany
| | | | | |
Collapse
|
40
|
Gatton ML, Cheng Q. Modeling the development of acquired clinical immunity to Plasmodium falciparum malaria. Infect Immun 2004; 72:6538-45. [PMID: 15501785 PMCID: PMC523055 DOI: 10.1128/iai.72.11.6538-6545.2004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Individuals living in regions where malaria is endemic develop an acquired immunity to malaria which enables them to remain asymptomatic while still carrying parasites. Field studies indicate that cumulative exposure to a variety of diverse Plasmodium parasites is required for the transition from symptomatic to asymptomatic malaria. This study used a simulation model of the within-host dynamics of P. falciparum to investigate the development of acquired clinical immunity under different transmission conditions and levels of parasite diversity. Antibodies developed to P. falciparum erythrocyte membrane protein 1 (PfEMP1), a clonally variant molecule, were assumed to be a key human immunological response to P. falciparum infection, along with responses to clonally conserved but polymorphic antigens. The time to the development of clinical immunity was found to be proportional to parasite diversity and inversely proportional to transmission intensity. The effect of early termination of symptomatic infections by chemotherapy was investigated and found not to inhibit the host's ability to develop acquired immunity. However, the time required to achieve this state was approximately double that compared to when no treatment was administered. This study demonstrates that an immune response primarily targeted against PfEMP1 has the ability to reduce clinical symptoms of infections irrespective of whether treatment is administered, supporting its role in the development of acquired clinical immunity. The results also illustrate a novel use for simulation models of P. falciparum infections, investigation of the influence of intervention strategies on the development of naturally acquired clinical immunity.
Collapse
Affiliation(s)
- Michelle L Gatton
- Australian Centre for International and Tropical Health and Nutrition, University of Queensland, Herston.
| | | |
Collapse
|
41
|
Deitsch KW, Hviid L. Variant surface antigens, virulence genes and the pathogenesis of malaria. Trends Parasitol 2004; 20:562-6. [PMID: 15522665 DOI: 10.1016/j.pt.2004.09.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The first Molecular Approaches to Malaria meeting was held 2-5 February 2000 in Lorne, Australia. Following the meeting, Brian Cooke, Mats Wahlgren and Ross Coppel predicted that research into the molecular details of the mechanisms behind sequestration of parasitized erythrocytes would "become increasingly more complicated, with further interactions, receptors, ligands and functional domains". Furthermore, they cautioned that "the challenge will be not to lose ourselves in the molecular detail, but remain focused on the role of [the var genes and other multigene families] in pathogenesis of malaria". We contemplate on these statements, following the recent second Molecular Approaches to Malaria meeting, which was held at the same venue on 2-5 February 2004.
Collapse
Affiliation(s)
- Kirk W Deitsch
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, 1300 York Avenue, W-704, Box 62, New York, NY 10021, USA
| | | |
Collapse
|
42
|
Sharma SK, Tyagi PK, Padhan K, Adak T, Subbarao SK. Malarial morbidity in tribal communities living in the forest and plain ecotypes of Orissa, India. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 2004; 98:459-68. [PMID: 15257795 DOI: 10.1179/000349804225003569] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A detailed epidemiological study of malarial morbidity was carried out in 13 'tribal' villages in the forest or plain ecotypes of Sundargarh district, Orissa, India. Longitudinal and cross-sectional, parasitological surveys were conducted in all the villages, to determine the incidence of malaria and the prevalence of malarial infection. The annual numbers of malaria cases/1000 were much higher in the forest (347.9) than on the plain (61.0). In the forest clinical malaria occurred more frequently in children than in adults but on the plain all age-groups were equally affected. In cross-sectional surveys, 14.1% of the subjects from the forest but only 2.8% of those from the plain were found smear-positive for malarial infection. The prevalences of infection in the forest area were highest in the young children (aged 1-5 years) and gradually declined with increasing age. The highest incidence of Plasmodium falciparum malaria (0.90 episode/person-year) was also recorded in the subjects from the forest who were aged 1-5 years. In the forest and plain communities surveyed, 78.5%-81.5% and 36.0%-52.0% of the children aged 2-9 years had detectable splenomegaly, respectively, indicating that the forest was hyper-endemic and the plain meso-endemic for malaria. Malaria is clearly a major problem among the tribal communities of Sundargarh, causing great morbidity and, consequently, considerable economic losses.
Collapse
Affiliation(s)
- S K Sharma
- Malaria Research Centre (ICMR), Field Station, Sector-5, Rourkela - 769 002, Orissa, India.
| | | | | | | | | |
Collapse
|
43
|
Mackinnon MJ, Read AF. Virulence in malaria: an evolutionary viewpoint. Philos Trans R Soc Lond B Biol Sci 2004; 359:965-86. [PMID: 15306410 PMCID: PMC1693375 DOI: 10.1098/rstb.2003.1414] [Citation(s) in RCA: 197] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Malaria parasites cause much morbidity and mortality to their human hosts. From our evolutionary perspective, this is because virulence is positively associated with parasite transmission rate. Natural selection therefore drives virulence upwards, but only to the point where the cost to transmission caused by host death begins to outweigh the transmission benefits. In this review, we summarize data from the laboratory rodent malaria model, Plasmodium chabaudi, and field data on the human malaria parasite, P. falciparum, in relation to this virulence trade-off hypothesis. The data from both species show strong positive correlations between asexual multiplication, transmission rate, infection length, morbidity and mortality, and therefore support the underlying assumptions of the hypothesis. Moreover, the P. falciparum data show that expected total lifetime transmission of the parasite is maximized in young children in whom the fitness cost of host mortality balances the fitness benefits of higher transmission rates and slower clearance rates, thus exhibiting the hypothesized virulence trade-off. This evolutionary explanation of virulence appears to accord well with the clinical and molecular explanations of pathogenesis that involve cytoadherence, red cell invasion and immune evasion, although direct evidence of the fitness advantages of these mechanisms is scarce. One implication of this evolutionary view of virulence is that parasite populations are expected to evolve new levels of virulence in response to medical interventions such as vaccines and drugs.
Collapse
Affiliation(s)
- Margaret J Mackinnon
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, Scotland, UK.
| | | |
Collapse
|
44
|
Recker M, Nee S, Bull PC, Kinyanjui S, Marsh K, Newbold C, Gupta S. Transient cross-reactive immune responses can orchestrate antigenic variation in malaria. Nature 2004; 429:555-8. [PMID: 15175751 DOI: 10.1038/nature02486] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2003] [Accepted: 03/09/2004] [Indexed: 11/09/2022]
Abstract
The malaria parasite Plasmodium falciparum has evolved to prolong its duration of infection by antigenic variation of a major immune target on the surface of the infected red blood cell. This immune evasion strategy depends on the sequential, rather than simultaneous, appearance of immunologically distinct variants. Although the molecular mechanisms by which a single organism switches between variants are known in part, it remains unclear how an entire population of parasites within the host can synchronize expression to avoid rapidly exhausting the variant repertoire. Here we show that short-lived, partially cross-reactive immune responses to parasite-infected erythrocyte surface antigens can produce a cascade of sequentially dominant antigenic variants, each of which is the most immunologically distinct from its preceding types. This model reconciles several previously unexplained and apparently conflicting epidemiological observations by demonstrating that individuals with stronger cross-reactive immune responses can, paradoxically, be more likely to sustain chronic infections. Antigenic variation has always been seen as an adaptation of the parasite to evade host defence: we show that the coordination necessary for the success of this strategy might be provided by the host.
Collapse
Affiliation(s)
- Mario Recker
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK
| | | | | | | | | | | | | |
Collapse
|
45
|
Rasti N, Wahlgren M, Chen Q. Molecular aspects of malaria pathogenesis. ACTA ACUST UNITED AC 2004; 41:9-26. [PMID: 15094163 DOI: 10.1016/j.femsim.2004.01.010] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2003] [Revised: 01/22/2004] [Accepted: 01/23/2004] [Indexed: 11/29/2022]
Abstract
Plasmodium falciparum being the most lethal plasmodiae is still a major cause of the disease burden and mortality in malaria endemic areas. Due to the wide spread drug resistance in combination with poor socio-economic situation in the vast majority of the endemic countries, malaria is today a great global challenge. The scientific community is, however, progressing. The 23 Mb genome of P. falciparum has been decoded and publicly available. Data of transcriptional profiling at certain developmental stages have already been generated. More than 50% of P. falciparum genes are transcribed constitutively in all the developmental stages of parasite life cycle. Functional disruption of these genes might have implications for parasite growth and development. Available microarray data indicate that P. falciparum preferentially expresses rif and stevor gene families at gametocyte and sporozoite stages while var genes are predominantly expressed at the erythrocytic stage. Gene regulation mechanisms of the variant gene families in P. falciparum are still not understood though some regulatory elements have been proposed. The occurrence of severe malaria is determined by both parasite and human host factors. Sequestration and antigenic variation are two of the evasion mechanisms utilized by P. falciparum in order to escape the human host defences. Understanding the molecular mechanisms underlying these phenomena is of a major importance and interest in malaria research. Here, we summarize and highlight the recent progress in molecular aspects of severe malaria.
Collapse
Affiliation(s)
- Niloofar Rasti
- Microbiology and Tumour Biology Centre, Karolinska Institute, Swedish Institute for Infectious Disease Control, Box 280, 171 77 Stockholm, Sweden
| | | | | |
Collapse
|
46
|
Allred DR, Al-Khedery B. Antigenic variation and cytoadhesion in Babesia bovis and Plasmodium falciparum: different logics achieve the same goal. Mol Biochem Parasitol 2004; 134:27-35. [PMID: 14747140 DOI: 10.1016/j.molbiopara.2003.09.012] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Babesia bovis is a protozoal hemoparasite of cattle which behaves in certain crucial respects like Plasmodium falciparum, despite being phylogenetically distant and having many differences in its life cycle. The shared behavioral attributes of rapid antigenic variation and cytoadhesion/sequestration are thought to contribute significantly to immune evasion, establishment of persistent infections, and disease pathology. Although differing in their genetic and biochemical strategies for achieving these behaviors, information from studies of each parasite may further our understanding of the overall host-parasite interaction. In this review we contrast the molecular basis and 'genetic logic' for these critical behaviors in the two parasites, with emphasis on the biology of B. bovis.
Collapse
Affiliation(s)
- David R Allred
- Department of Pathobiology, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611-0880, USA.
| | | |
Collapse
|
47
|
Cabrera G, Yone C, Tebo AE, van Aaken J, Lell B, Kremsner PG, Luty AJF. Immunoglobulin G isotype responses to variant surface antigens of Plasmodium falciparum in healthy Gabonese adults and children during and after successive malaria attacks. Infect Immun 2004; 72:284-94. [PMID: 14688107 PMCID: PMC344001 DOI: 10.1128/iai.72.1.284-294.2004] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2003] [Revised: 09/29/2003] [Accepted: 10/08/2003] [Indexed: 11/20/2022] Open
Abstract
We assessed immunoglobulin G (IgG) isotype responses with specificity for the variant surface antigens (VSA) of heterologous Plasmodium falciparum isolates by using flow cytometry and plasma from healthy Gabonese adults and from children during and after two consecutive malaria episodes. The individual isolate-specific antibody profiles differed markedly in terms of their isotype content but were similar for healthy adults and healthy uninfected children. In healthy adults, IgG3 and IgG2 responses were the highest, while in healthy children, IgG3 and IgG4 predominated. A transiently elevated IgG1 response was observed during the second of two successive malaria episodes in children, signaling P. falciparum infection-induced cross-reactive anti-VSA responses. Our findings highlight the prominence of IgG3 in the overall profile of these responses but also indicate a marked age-related increase in the prevalence of anti-VSA antibodies of the classically noncytophilic IgG2 isotype, possibly reflecting the high frequency of the histidine-131 variant of FcgammaRIIA in the Gabonese population.
Collapse
Affiliation(s)
- Gerardo Cabrera
- Department of Parasitology, Institute for Tropical Medicine, University of Tübingen, D-72074 Tübingen, Germany
| | | | | | | | | | | | | |
Collapse
|
48
|
Hviid L, Staalsoe T, Nielsen MA, Theander TG. Specificity and cross-reactivity of Plasmodium falciparum variant surface antigen-specific antibody responses. Infect Immun 2003; 71:2296. [PMID: 12654861 PMCID: PMC152017 DOI: 10.1128/iai.71.4.2296.2003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
49
|
Affiliation(s)
- D J Roberts
- Nuffield Department of Clinical Laboratory Sciences and National Blood Service, John Radcliffe Hospital, Headington, Oxford OX3 9DU, United Kingdom.
| |
Collapse
|