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Ranjit A, Wylie BJ. Malaria in Pregnancy, Current Challenges, and Emerging Prevention Strategies in a Warming Climate. Clin Obstet Gynecol 2024; 67:620-632. [PMID: 39061127 DOI: 10.1097/grf.0000000000000888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2024]
Abstract
Malaria still presents a grave threat to the health of pregnancies worldwide with prevention currently stalling as traditional control and prevention strategies are limited by both insecticide and drug resistance. Furthermore, climate change is bringing malaria to locations where it was once eradicated and intensifying malaria in other areas. Even where malaria is not currently common, obstetricians will need to understand the pathogenesis of the disease, how it is transmitted, methods for prevention and treatment in pregnancy, and promising emerging strategies such as vaccines. A renewed global response is needed for this age-old disease in which pregnancy poses specific susceptibility.
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Affiliation(s)
- Anju Ranjit
- Department of Obstetrics, Gynecology and Reproductive Sciences, Division of Maternal-Fetal Medicine, University of California, San Francisco
| | - Blair J Wylie
- Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, Columbia University Medical Center, New York, New York
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2
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Ventimiglia NT, Stucke EM, Coulibaly D, Berry AA, Lyke KE, Laurens MB, Bailey JA, Adams M, Niangaly A, Kone AK, Takala-Harrison S, Kouriba B, Doumbo OK, Felgner PL, Plowe CV, Thera MA, Travassos MA. Malian adults maintain serologic responses to virulent PfEMP1s amid seasonal patterns of fluctuation. Sci Rep 2021; 11:14401. [PMID: 34257318 PMCID: PMC8277812 DOI: 10.1038/s41598-021-92974-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 06/08/2021] [Indexed: 12/03/2022] Open
Abstract
Plasmodium falciparum erythrocyte membrane protein-1s (PfEMP1s), diverse malaria proteins expressed on the infected erythrocyte surface, play an important role in pathogenesis, mediating adhesion to host vascular endothelium. Antibodies to particular non-CD36-binding PfEMP1s are associated with protection against severe disease. We hypothesized that given lifelong P. falciparum exposure, Malian adults would have broad PfEMP1 serorecognition and high seroreactivity levels during follow-up, particularly to non-CD36-binding PfEMP1s such as those that attach to endothelial protein C receptor (EPCR) and intercellular adhesion molecule-1 (ICAM-1). Using a protein microarray, we determined serologic responses to 166 reference PfEMP1 fragments during a dry and subsequent malaria transmission season in Malian adults. Malian adult sera had PfEMP1 serologic responses throughout the year, with decreased reactivity to a small subset of PfEMP1 fragments during the dry season and increases in reactivity to a different subset of PfEMP1 fragments during the subsequent peak malaria transmission season, especially for intracellular PfEMP1 domains. For some individuals, PfEMP1 serologic responses increased after the dry season, suggesting antigenic switching during asymptomatic infection. Adults were more likely to experience variable serorecognition of CD36-binding PfEMP1s than non-CD36-binding PfEMP1s that bind EPCR or ICAM-1, which remained serorecognized throughout the year. Sustained seroreactivity to non-CD36-binding PfEMP1s throughout adulthood amid seasonal fluctuation patterns may reflect underlying protective severe malaria immunity and merits further investigation.
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Affiliation(s)
| | - Emily M Stucke
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Drissa Coulibaly
- University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Andrea A Berry
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Kirsten E Lyke
- University of Maryland School of Medicine, Baltimore, MD, USA
| | | | - Jason A Bailey
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Matthew Adams
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Amadou Niangaly
- University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Abdoulaye K Kone
- University of Sciences, Techniques and Technologies, Bamako, Mali
| | | | - Bourema Kouriba
- University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Ogobara K Doumbo
- University of Sciences, Techniques and Technologies, Bamako, Mali
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3
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Galatas B, Bassat Q, Mayor A. Malaria Parasites in the Asymptomatic: Looking for the Hay in the Haystack. Trends Parasitol 2015; 32:296-308. [PMID: 26708404 DOI: 10.1016/j.pt.2015.11.015] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 11/21/2015] [Accepted: 11/24/2015] [Indexed: 12/11/2022]
Abstract
With malaria elimination back on the international agenda, programs face the challenge of targeting all Plasmodium infections, not only symptomatic cases. As asymptomatic individuals are unlikely to seek treatment, they are missed by passive surveillance while remaining infectious to mosquitoes, thus acting as silent reservoirs of transmission. To estimate the risk of asymptomatic infections in various phases of malaria elimination, we need a deeper understanding of the underlying mechanisms favoring carriage over disease, which may involve both pathogen and host factors. Here we review our current knowledge on the determinants leading to Plasmodium falciparum symptomless infections. Understanding the host-pathogen interactions that are most likely to affect transitions between malaria disease states could guide the development of tools to tackle asymptomatic carriers in elimination settings.
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Affiliation(s)
- Beatriz Galatas
- ISGlobal, Barcelona Centre for International Health Research (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain; Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Quique Bassat
- ISGlobal, Barcelona Centre for International Health Research (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain; Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Alfredo Mayor
- ISGlobal, Barcelona Centre for International Health Research (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain; Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique.
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Prevalence of Malaria Infection and Risk Factors Associated with Anaemia among Pregnant Women in Semiurban Community of Hazaribag, Jharkhand, India. BIOMED RESEARCH INTERNATIONAL 2015; 2015:740512. [PMID: 26783526 PMCID: PMC4691455 DOI: 10.1155/2015/740512] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 08/13/2015] [Indexed: 01/11/2023]
Abstract
The escalating burden, pathogenesis, and clinical sequel of malaria during pregnancy have combinatorial adverse impact on both mother and foetus that further perplexed the situation of diagnosis, treatment, and prevention. This prompted us to evaluate the status of population at risk of MIP in Hazaribag, Jharkhand, India. Cross-sectional study was conducted over a year at Sadar Hospital, Hazaribag. Malaria was screened using blood smear and/or RDT. Anaemia was defined as haemoglobin concentration. Pretested questionnaires were used to gather sociodemographic, clinical, and obstetrical data. The prevalence of MIP was 5.4% and 4.3% at ANC and DU, and 13.2% malaria was in women without pregnancy. Interestingly, majority were asymptomatically infected with P. vivax (over 85%) at ANC and DU. Peripheral parasitemia was significantly associated with fever within past week, rural origin of subjects, and first/second pregnancies in multivariate analysis, with the highest risk factor associated with fever followed by rural residence. Strikingly in cohort, anaemia was prevalent in 86% at ANC as compared to 72% at DU, whereas severe anaemia was 13.6% and 7.8% at ANC and DU. Even more anaemia prevalence was observed in MIP group (88% and 89% at ANC and DU), whereas severe anaemia was 23% and 21%, respectively. In view of observed impact of anaemia, parasitemia and asymptomatic infection of P. vivax during pregnancy and delivery suggest prompt diagnosis regardless of symptoms and comprehensive drug regime should be offered to pregnant women in association with existing measures in clinical spectrum of MIP, delivery, and its outcome.
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5
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Brown A, Turner L, Christoffersen S, Andrews KA, Szestak T, Zhao Y, Larsen S, Craig AG, Higgins MK. Molecular architecture of a complex between an adhesion protein from the malaria parasite and intracellular adhesion molecule 1. J Biol Chem 2013; 288:5992-6003. [PMID: 23297413 PMCID: PMC3581401 DOI: 10.1074/jbc.m112.416347] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 12/20/2012] [Indexed: 11/06/2022] Open
Abstract
The adhesion of Plasmodium falciparum-infected erythrocytes to human tissues or endothelium is central to the pathology caused by the parasite during malaria. It contributes to the avoidance of parasite clearance by the spleen and to the specific pathologies of cerebral and placental malaria. The PfEMP1 family of adhesive proteins is responsible for this sequestration by mediating interactions with diverse human ligands. In addition, as the primary targets of acquired, protective immunity, the PfEMP1s are potential vaccine candidates. PfEMP1s contain large extracellular ectodomains made from CIDR (cysteine-rich interdomain regions) and DBL (Duffy-binding-like) domains and show extensive variation in sequence, size, and domain organization. Here we use biophysical methods to characterize the entire ∼300-kDa ectodomain from IT4VAR13, a protein that interacts with the host receptor, intercellular adhesion molecule-1 (ICAM-1). We show through small angle x-ray scattering that IT4VAR13 is rigid, elongated, and monomeric. We also show that it interacts with ICAM-1 through the DBLβ domain alone, forming a 1:1 complex. These studies provide a first low resolution structural view of a PfEMP1 ectodomain in complex with its ligand. They show that it combines a modular domain arrangement consisting of individual ligand binding domains, with a defined higher order architecture that exposes the ICAM-1 binding surface to allow adhesion.
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Affiliation(s)
- Alan Brown
- From the Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, United Kingdom
| | - Louise Turner
- Centre for Molecular Parasitology, University of Copenhagen, Øster Farimagsgade 5, Bygning 221014, Copenhagen, Denmark
| | - Stig Christoffersen
- Centre for Molecular Parasitology, University of Copenhagen, Øster Farimagsgade 5, Bygning 221014, Copenhagen, Denmark
- the Department of Chemistry, University of Copenhagen, Universitetsparken 5 2100 Copenhagen, Denmark
| | - Katrina A. Andrews
- From the Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, United Kingdom
| | - Tadge Szestak
- Molecular and Biochemical Parasitology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, United Kingdom
| | - Yuguang Zhao
- Division of Structural Biology, University of Oxford, Oxford, OX3 7BN, and
| | - Sine Larsen
- the Department of Chemistry, University of Copenhagen, Universitetsparken 5 2100 Copenhagen, Denmark
| | - Alister G. Craig
- Molecular and Biochemical Parasitology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, United Kingdom
| | - Matthew K. Higgins
- the Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, United Kingdom
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6
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Adhesion of Plasmodium falciparum-infected erythrocytes to human cells: molecular mechanisms and therapeutic implications. Expert Rev Mol Med 2009; 11:e16. [PMID: 19467172 PMCID: PMC2878476 DOI: 10.1017/s1462399409001082] [Citation(s) in RCA: 249] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Severe malaria has a high mortality rate (15–20%) despite treatment with
effective antimalarial drugs. Adjunctive therapies for severe malaria that target the
underlying disease process are therefore urgently required. Adhesion of erythrocytes
infected with Plasmodium falciparum to human cells has a key role in the
pathogenesis of life-threatening malaria and could be targeted with antiadhesion therapy.
Parasite adhesion interactions include binding to endothelial cells (cytoadherence),
rosetting with uninfected erythrocytes and platelet-mediated clumping of infected
erythrocytes. Recent research has started to define the molecular mechanisms of parasite
adhesion, and antiadhesion therapies are being explored. However, many fundamental
questions regarding the role of parasite adhesion in severe malaria remain unanswered.
There is strong evidence that rosetting contributes to severe malaria in sub-Saharan
Africa; however, the identity of other parasite adhesion phenotypes that are implicated in
disease pathogenesis remains unclear. In addition, the possibility of geographic variation
in adhesion phenotypes causing severe malaria, linked to differences in malaria
transmission levels and host immunity, has been neglected. Further research is needed to
realise the untapped potential of antiadhesion adjunctive therapies, which could
revolutionise the treatment of severe malaria and reduce the high mortality rate of the
disease.
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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.
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Affiliation(s)
- Denise L Doolan
- Queensland Institute of Medical Research, The Bancroft Centre, Post Office Royal Brisbane Hospital, Brisbane, Queensland 4029, Australia.
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8
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Boutlis CS, Yeo TW, Anstey NM. Malaria tolerance--for whom the cell tolls? Trends Parasitol 2006; 22:371-7. [PMID: 16784889 PMCID: PMC2766419 DOI: 10.1016/j.pt.2006.06.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2005] [Revised: 05/04/2006] [Accepted: 06/02/2006] [Indexed: 01/01/2023]
Abstract
How is it that individuals exposed to intense malaria transmission can tolerate the presence of malaria parasites in their blood at levels that would produce fever in others? In light of evidence discounting a role for nitric oxide or antibodies to plasmodial glycosylphosphatidylinositols in maintaining this tolerant state, refractoriness to toxin-induced Toll-like receptor-mediated signalling has emerged as a likely explanation that links malarial and bacterial endotoxin tolerance. Understanding the mechanisms underlying tolerance and the potential for cross-tolerization has significant implications for understanding the potential for antitoxic vaccine strategies, as well as interactions between different malaria species and between malaria and other human parasites.
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Affiliation(s)
- Craig S Boutlis
- Division of Tropical and Emerging Infectious Diseases, Menzies School of Health Research, Charles Darwin University, PO Box 41096, Casuarina, NT 0811, Australia.
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Franke-Fayard B, Janse CJ, Cunha-Rodrigues M, Ramesar J, Büscher P, Que I, Löwik C, Voshol PJ, den Boer MAM, van Duinen SG, Febbraio M, Mota MM, Waters AP. Murine malaria parasite sequestration: CD36 is the major receptor, but cerebral pathology is unlinked to sequestration. Proc Natl Acad Sci U S A 2005; 102:11468-73. [PMID: 16051702 PMCID: PMC1183563 DOI: 10.1073/pnas.0503386102] [Citation(s) in RCA: 248] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Sequestration of malaria-parasite-infected erythrocytes in the microvasculature of organs is thought to be a significant cause of pathology. Cerebral malaria (CM) is a major complication of Plasmodium falciparum infections, and PfEMP1-mediated sequestration of infected red blood cells has been considered to be the major feature leading to CM-related pathology. We report a system for the real-time in vivo imaging of sequestration using transgenic luciferase-expressing parasites of the rodent malaria parasite Plasmodium berghei. These studies revealed that: (i) as expected, lung tissue is a major site, but, unexpectedly, adipose tissue contributes significantly to sequestration, and (ii) the class II scavenger-receptor CD36 to which PfEMP1 can bind is also the major receptor for P. berghei sequestration, indicating a role for alternative parasite ligands, because orthologues of PfEMP1 are absent from rodent malaria parasites, and, importantly, (iii) cerebral complications still develop in the absence of CD36-mediated sequestration, dissociating parasite sequestration from CM-associated pathology. Real-time in vivo imaging of parasitic processes may be used to evaluate the molecular basis of pathology and develop strategies to prevent pathology.
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Affiliation(s)
- Blandine Franke-Fayard
- Department of Parasitology, Leiden University Medical Center, 2300 RC, Leiden, The Netherlands
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10
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Malhotra I, Mungai P, Muchiri E, Ouma J, Sharma S, Kazura JW, King CL. Distinct Th1- and Th2-Type prenatal cytokine responses to Plasmodium falciparum erythrocyte invasion ligands. Infect Immun 2005; 73:3462-70. [PMID: 15908375 PMCID: PMC1111871 DOI: 10.1128/iai.73.6.3462-3470.2005] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Prenatal immunity to Plasmodium falciparum merozoite proteins involved in erythrocyte invasion may contribute to the partial protection against malaria that is acquired during infancy in areas of stable malaria transmission. We examined newborn and maternal cytokine and antibody responses to merozoite surface protein-1 (MSP-1), ribosomal phosphoprotein P0 (PfP0), and region II of erythrocyte binding antigen-175 (EBA-175) in infant-mother pairs in Kenya. Overall, 82 of 167 (50%), 106 of 176 (60%), and 38 of 84 (45%) cord blood lymphocytes (CBL) from newborns produced one or more cytokines in response to MSP-1, PfP0, and EBA-175, respectively. Newborns of primigravid and/or malaria-infected women were more likely to have antigen-responsive CBL than were newborns of multigravid and/or uninfected women at delivery. Newborn cytokine responses did not match those of their mothers and fell into three distinct categories, Th1 (21 of 55 CBL donors produced only gamma interferon and/or interleukin 2 [IL-2]), Th2 (21 of 55 produced only IL-5 and/or IL-13), and mixed Th1/Th2 (13 of 55). Newborns produced more IL-10 than adults. High and low levels of cord blood IL-12 p70 production induced by anti-CD40 activation were associated with malaria-specific Th1 and Th2 responses, respectively. Antigen-responsive CBL in some newborns were detected only after depletion of IL-10-secreting CD8 cells with enrichment for CD4 cells. These data indicate that prenatal sensitization to blood-stage Plasmodium falciparum occurs frequently in areas where malaria is holoendemic. Modulation of this immunity, possibly by maternal parity and malaria, may affect the acquisition of protective immunity against malaria during infancy.
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Affiliation(s)
- Indu Malhotra
- Center for Global Health and Diseases, Case Western Reserve University, 2103 Cornell Rd., WRC Room 4132, Cleveland, OH 44106-7286, USA
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Eda S, Sherman IW. Plasmodium falciparum-infected erythrocytes bind to the RGD motif of fibronectin via the band 3-related adhesin. Exp Parasitol 2004; 107:157-62. [PMID: 15363941 DOI: 10.1016/j.exppara.2004.06.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2003] [Revised: 05/17/2004] [Accepted: 06/14/2004] [Indexed: 01/05/2023]
Abstract
Previously it was shown that Plasmodium falciparum-infected erythrocytes bound to thrombospondin by the interaction of the peptidic sequence, HPLQKTY, of the band 3 protein of infected erythrocytes, and the RGD motif of thrombospondin. Here, we show that falciparum-parasitized erythrocytes bind to immobilized fibronectin by the RGD sequence of fibronectin. Involvement of the HPLQKTY region of band 3 in binding was demonstrated by inhibition of adhesion of parasitized erythrocytes to fibronectin by an HPLQKTY-containing peptide and the binding of the HPLQKTY peptide to the RGD sequence of immobilized fibronectin. Since fibronectin occurs on endothelial cells and platelets, this interaction may contribute to the binding of falciparum-infected erythrocytes to such host cells.
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Affiliation(s)
- Shigetoshi Eda
- Department of Biology, University of California, Riverside 92521, USA
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12
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Doolan DL, Aguiar JC, Weiss WR, Sette A, Felgner PL, Regis DP, Quinones-Casas P, Yates JR, Blair PL, Richie TL, Hoffman SL, Carucci DJ. Utilization of genomic sequence information to develop malaria vaccines. J Exp Biol 2003; 206:3789-802. [PMID: 14506214 DOI: 10.1242/jeb.00615] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYRecent advances in the fields of genomics, proteomics and molecular immunology offer tremendous opportunities for the development of novel interventions against public health threats, including malaria. However, there is currently no algorithm that can effectively identify the targets of protective T cell or antibody responses from genomic data. Furthermore, the identification of antigens that will stimulate the most effective immunity against the target pathogen is problematic, particularly if the genome is large. Malaria is an attractive model for the development and validation of approaches to translate genomic information to vaccine development because of the critical need for effective anti-malarial interventions and because the Plasmodium parasite is a complex multistage pathogen targeted by multiple immune responses. Sterile protective immunity can be achieved by immunization with radiation-attenuated sporozoites, and anti-disease immunity can be induced in residents in malaria-endemic areas. However, the 23 Mb Plasmodium falciparum genome encodes more than 5300 proteins, each of which is a potential target of protective immune responses. The current generation of subunit vaccines is based on a single or few antigens and therefore might elicit too narrow a breadth of response. We are working towards the development of a new generation vaccine based on the presumption that duplicating the protection induced by the whole organism may require a vaccine nearly as complex as the organism itself. Here, we present our strategy to exploit the genomic sequence of P. falciparum for malaria vaccine development.
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Affiliation(s)
- D L Doolan
- Malaria Program, Naval Medical Research Center, Silver Spring, MD 20910-7500, USA.
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13
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Gatton ML, Peters JM, Fowler EV, Cheng Q. Switching rates of Plasmodium falciparum var genes: faster than we thought? Trends Parasitol 2003; 19:202-8. [PMID: 12763425 DOI: 10.1016/s1471-4922(03)00067-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Plasmodium falciparum undergoes antigenic variation by switching the expressed erythrocyte membrane protein (PfEMP)1. This family of proteins plays an important role in the development of chronic, recrudescent P. falciparum malaria, acquired immunity and severe malaria. However, little is known about the switching mechanism or switching rates in the human host. Here, we estimate the switch rate of var genes, using recently published data describing the var gene transcripts detected in blood taken from human volunteers during acute P. falciparum infections and a mathematical model of the in-host dynamics. The overall switch rate of PfEMP1 predicted during the initial stage of infection ( approximately 18% switching parasites per generation) is much higher than previously reported. The implications of the predicted switching rates are discussed.
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Affiliation(s)
- Michelle L Gatton
- Malaria Biology Laboratory, Queensland Institute of Medical Research, PO Royal Brisbane Hospital, Queensland 4029, Australia.
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14
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Achur RN, Valiyaveettil M, Gowda DC. The low sulfated chondroitin sulfate proteoglycans of human placenta have sulfate group-clustered domains that can efficiently bind Plasmodium falciparum-infected erythrocytes. J Biol Chem 2003; 278:11705-13. [PMID: 12517756 DOI: 10.1074/jbc.m211015200] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Plasmodium falciparum infection in pregnant women results in the chondroitin 4-sulfate-mediated adherence of the parasite-infected red blood cells (IRBCs) in the placenta, adversely affecting the health of the fetus and mother. We have previously shown that unusually low sulfated chondroitin sulfate proteoglycans (CSPGs) in the intervillous spaces of the placenta are the receptors for IRBC adhesion, which involves a chondroitin 4-sulfate motif consisting of six disaccharide moieties with approximately 30% 4-sulfated residues. However, it was puzzling how the placental CSPGs, which have only approximately 8% of the disaccharide 4-sulfated, could efficiently bind IRBCs. Thus, we undertook to determine the precise structural features of the CS chains of placental CSPGs that interact with IRBCs. We show that the placental CSPGs are a mixture of two major populations, which are similar by all criteria except differing in their sulfate contents; 2-3% and 9-14% of the disaccharide units of the CS chains are 4-sulfated, and the remainder are nonsulfated. The majority of the sulfate groups in the CSPGs are clustered in CS chain domains consisting of 6-14 repeating disaccharide units. While the sulfate-rich regions of the CS chains contain 20-28% 4-sulfated disaccharides, the other regions have little or no sulfate. Further, we find that the placental CSPGs are able to efficiently bind IRBCs due to the presence of 4-sulfated disaccharide clusters. The oligosaccharides corresponding to the sulfate-rich domains of the CS chains efficiently inhibited IRBC adhesion. Thus, our data demonstrate, for the first time, the unique distribution of sulfate groups in the CS chains of placental CSPGs and that these sulfate-clustered domains have the necessary structural elements for the efficient adhesion of IRBCs, although the CS chains have an overall low degree of sulfation.
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Affiliation(s)
- Rajeshwara N Achur
- Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, USA
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15
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Mercereau-Puijalon O, Barale JC, Bischoff E. Three multigene families in Plasmodium parasites: facts and questions. Int J Parasitol 2002; 32:1323-44. [PMID: 12350369 DOI: 10.1016/s0020-7519(02)00111-x] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Multigene families optimise fitness by providing a set of related genes with possibly different temporal and/or topological expression patterns. We analyse here the structural organisation and sequence diversity of the rDNA, sera and var C Plasmodium falciparum families, and discuss their consequences for parasite biology. The low rDNA copy number, which reduces reshuffling, is probably the corollary of the need for functionally distinct rRNAs in the insect and in the vertebrate host. The unusual intra-genome and population rDNA sequence diversity results in cells equipped with mosaic ribosome sets. The functional constraints are such that ribosome compatibility could influence parasite fitness and contribute to population structuring. Unlike the dispersed rDNA units, the sera family is arranged as a tandem gene cluster, with seven contiguous similar genes, and one more distantly related paralog. We address the question of the inclusion criteria in family definition. We discuss the results concerning the SERA proteins expression and function in the context of the long overlooked multigene family. The var C module is shared by var genes, 'orphan' var C and var C pseudogenes. Analysis of 125 var C deduced protein sequences highlights a well-conserved framework, including putative phosphorylation sites, consistent with the proposed function of mediating interaction with cytoskeletal proteins. The 5' and 3' flanking sequences of the var C pseudogenes are heterogeneous. In contrast, the flanking sequences of the uninterrupted var C modules show remarkable conservation. This is interesting in view of the silencing activity of the var intronic sequence on var expression. The 5' flanking sequence dichotomy reported for internal and sub-telomeric var genes extends to the 3' flanking sequences. This has profound implications for transcription regulation and generation of diversity. The var C family suggests a role for pseudogenes as a diversity reservoir and in genome dynamics by promoting ectopic recombination.
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Affiliation(s)
- Odile Mercereau-Puijalon
- Unité d'Immunologie Moléculaire des Parasites, Unité de Recherche Associée 1960 du Centre National de la Recherche Scientifique, Institut Pasteur, 25 rue du Dr ROUX, 75015, Paris, France.
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Lekana Douki JB, Traore B, Costa FTM, Fusaï T, Pouvelle B, Sterkers Y, Scherf A, Gysin J. Sequestration of Plasmodium falciparum-infected erythrocytes to chondroitin sulfate A, a receptor for maternal malaria: monoclonal antibodies against the native parasite ligand reveal pan-reactive epitopes in placental isolates. Blood 2002; 100:1478-83. [PMID: 12149234 DOI: 10.1182/blood-2002-01-0315] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plasmodium falciparum parasites express variant adhesion molecules on the surface of infected erythrocytes (IEs), which act as targets for natural protection. Recently it was shown that IE sequestration in the placenta is mediated by binding to chondroitin sulfate A via the duffy binding-like (DBL)-gamma 3 domain of P falciparum erythrocyte membrane protein 1 (PfEMP1(CSA)). Conventional immunization procedures rarely result in the successful production of monoclonal antibodies (mAbs) against such conformational vaccine candidates. Here, we show that this difficulty can be overcome by rendering Balb/c mice B cells tolerant to the surface of human erythrocytes or Chinese hamster ovary (CHO) cells before injecting P falciparum IEs or transfected CHO cells expressing the chondroitin sulfate A (CSA)-binding domain (DBL-gamma 3) of the FCR3 var(CSA) gene. We fused spleen cells with P3U1 cells and obtained between 20% and 60% mAbs that specifically label the surface of mature infected erythrocytes of the CSA phenotype (mIE(CSA)) but not of other adhesive phenotypes. Surprisingly, 70.8% of the 43 mAbs analyzed in this work were IgM. All mAbs immunoprecipitated PfEMP1(CSA) from extracts of (125)I surface-labeled IE(CSA). Several mAbs bound efficiently to the surface of CSA-binding parasites from different geographic areas and to placental isolates from West Africa. The cross-reactive mAbs are directed against the DBL-gamma 3(CSA), demonstrating that this domain, which mediates CSA binding, is able to induce a pan-reactive immune response. This work is an important step toward the development of a DBL-gamma 3-based vaccine that could protect pregnant women from pathogenesis. )
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Affiliation(s)
- Jean-Bernard Lekana Douki
- Unité de Parasitologie Expérimentale, Faculté de Médecine, Université de la Méditerranée (Aix-Marseille II), Marseille, France
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Salanti A, Jensen ATR, Zornig HD, Staalsoe T, Joergensen L, Nielsen MA, Khattab A, Arnot DE, Klinkert MQ, Hviid L, Theander TG. A sub-family of common and highly conserved Plasmodium falciparum var genes. Mol Biochem Parasitol 2002; 122:111-5. [PMID: 12076777 DOI: 10.1016/s0166-6851(02)00080-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Ali Salanti
- Centre for Medical Parasitology at Institute for Medical Microbiology and Immunology, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
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Hoffman SL, Subramanian GM, Collins FH, Venter JC. Plasmodium, human and Anopheles genomics and malaria. Nature 2002; 415:702-9. [PMID: 11832959 DOI: 10.1038/415702a] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The Plasmodium spp. parasites that cause malaria are transmitted to humans by Anopheles spp. mosquitoes. Scientists have now amassed a great body of knowledge about the parasite, its mosquito vector and human host. Yet this year there will be 300-500 million new malaria infections and 1-3 million deaths caused by the disease. We believe that integrated analyses of genome sequence, DNA polymorphisms, and messenger RNA and protein expression profiles will lead to greater understanding of the molecular basis of vector-human and host-parasite interactions and provide strategies to build upon these insights to develop interventions to mitigate human morbidity and mortality from malaria.
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Affiliation(s)
- Stephen L Hoffman
- Celera Genomics, 45 West Gude Drive, Rockville, Maryland 20850, USA.
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Abstract
DNA microarrays are a powerful tool for the analysis of RNA and DNA composition on a whole-genome scale. The first applications of this technology in parasitology are in place. This review examines the various approaches to Plasmodium transcript-profiling that are being adopted using DNA microarray analysis and discusses additional strategies for obtaining and collating information relevant to the search for drug and vaccine candidates in malaria.
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