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Poespoprodjo JR, Hafiidhaturrahmah, Sariyanti N, Indrawanti R, McLean ARD, Simpson JA, Kenangalem E, Burdam FH, Noviyanti R, Trianty L, Fadhilah C, Soenarto Y, Price RN. Intermittent screening and treatment for malaria complementary to routine immunisation in the first year of life in Papua, Indonesia: a cluster randomised superiority trial. BMC Med 2022; 20:190. [PMID: 35672703 PMCID: PMC9175359 DOI: 10.1186/s12916-022-02394-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 05/04/2022] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND In Papua (Indonesia), infants with P. falciparum and/or P. vivax malaria are at risk of severe anaemia and death. We hypothesized that in an area of high malaria transmission, intermittent screening and treatment of infants with malaria (ISTi) will reduce morbidity compared to passive case detection (PCDi). METHODS We conducted a cluster randomised, open label, superiority trial. A total of 21 clusters of village health posts (VHP) were randomised 1:1 to either IST for infants coinciding with 4 routine immunisation visits or PCDi. Healthy term infants born to consenting mothers enrolled into a maternal malaria cluster randomised trial were included in the study and followed for 12 months. Point of care malaria rapid diagnostic tests were used to detect peripheral parasitaemia at 2, 3, 4 and 9 months old in all infants in ISTi clusters and when symptomatic in PCDi clusters. Infants with detected peripheral parasitaemia were treated with dihydroartemisinin-piperaquine. The co-primary outcomes were the incidence rate of clinical malaria in the first year of life and the prevalence of parasitaemia at age 12 months. The incidence rate ratio and prevalence ratio between ISTi and PCDi were estimated using mixed-effects Poisson and log-binomial regression modelling (accounting for clustering at VHP level). RESULTS Between May 2014 and February 2017, 757 infants were enrolled into the study, 313 into 10 ISTi clusters, and 444 into 11 PCDi clusters. Overall, 132 episodes of parasitaemia were detected, of whom 17 (12.9%) were in symptomatic infants. Over 12 months, the incidence rate (IR) of clinical malaria was 24 [95% CI, 10-50] per 1000 children-years at risk in the ISTi arm and 19 [95% CI, 8,38] per 1000 children-years in the PCDi arm (adjusted incidence rate ratio [aIRR] 1.77 [95% CI, 0.62-5.01]; p = 0.280). The prevalence of parasitaemia at 12 months was 13% (33/254) in the IST clusters and 15% (57/379) in the PCD clusters (adjusted prevalence ratio (aPR) = 0.92 (95% CI, 0.70-1.21), p = 0.55). There was no difference in the risk of anaemia between treatment arms. CONCLUSIONS In high malaria transmission area outside of Africa, our study suggests that compared to PCDi, ISTi offers no significant benefit in reducing the risk of clinical malaria in infants born to women receiving effective protection from malaria during pregnancy. TRIAL REGISTRATION ClinicalTrials.gov NCT02001428 , registered on 20 Nov 2013.
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Affiliation(s)
- Jeanne Rini Poespoprodjo
- Centre for Child Health and Department of Child Health, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Jl. Kesehatan no.1, Sekip, Yogyakarta, 55284, Indonesia. .,Timika Malaria Research Facility, Papuan Health and Community Development Foundation, Jl. SP2-SP5, RSMM Area, Timika, Papua, 99910, Indonesia. .,Mimika District Hospital and District Health Authority, Jl. Yos Sudarso, Timika, Papua, 99910, Indonesia.
| | - Hafiidhaturrahmah
- Timika Malaria Research Facility, Papuan Health and Community Development Foundation, Jl. SP2-SP5, RSMM Area, Timika, Papua, 99910, Indonesia
| | - Novita Sariyanti
- Timika Malaria Research Facility, Papuan Health and Community Development Foundation, Jl. SP2-SP5, RSMM Area, Timika, Papua, 99910, Indonesia
| | - Ratni Indrawanti
- Centre for Child Health and Department of Child Health, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Jl. Kesehatan no.1, Sekip, Yogyakarta, 55284, Indonesia
| | - Alistair R D McLean
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, 207 Bouverie Street, VIC, 3010, Melbourne, Australia
| | - Julie A Simpson
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, 207 Bouverie Street, VIC, 3010, Melbourne, Australia
| | - Enny Kenangalem
- Timika Malaria Research Facility, Papuan Health and Community Development Foundation, Jl. SP2-SP5, RSMM Area, Timika, Papua, 99910, Indonesia
| | - Faustina Helena Burdam
- Timika Malaria Research Facility, Papuan Health and Community Development Foundation, Jl. SP2-SP5, RSMM Area, Timika, Papua, 99910, Indonesia.,Mimika District Hospital and District Health Authority, Jl. Yos Sudarso, Timika, Papua, 99910, Indonesia
| | - Rintis Noviyanti
- Eijkman Institute for Molecular Biology, Jl. Diponegoro No.69, Jakarta, 10430, Indonesia
| | - Leily Trianty
- Eijkman Institute for Molecular Biology, Jl. Diponegoro No.69, Jakarta, 10430, Indonesia
| | - Chairunisa Fadhilah
- Eijkman Institute for Molecular Biology, Jl. Diponegoro No.69, Jakarta, 10430, Indonesia
| | - Yati Soenarto
- Centre for Child Health and Department of Child Health, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Jl. Kesehatan no.1, Sekip, Yogyakarta, 55284, Indonesia
| | - Ric N Price
- Global Health Division, Menzies School of Health Research and Charles Darwin University, PO Box 41096, Casuarina, Darwin, NT, 0811, Australia.,Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX37LJ, UK.,Mahidol-Oxford Tropical Medicine Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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2
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Zehner N, Adrama H, Kakuru A, Andra T, Kajubi R, Conrad M, Nankya F, Clark TD, Kamya M, Rodriguez-Barraquer I, Dorsey G, Jagannathan P. Age-related Changes in Malaria Clinical Phenotypes During Infancy are Modified by Sickle Cell Trait. Clin Infect Dis 2021; 73:1887-1895. [PMID: 33738485 PMCID: PMC8599196 DOI: 10.1093/cid/ciab245] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Indexed: 12/02/2022] Open
Abstract
Background Infants are protected against Plasmodium falciparum malaria. Mechanisms that drive this protection remain unclear due to a poor understanding of malaria clinical phenotypes during infancy. Methods We enrolled a birth cohort of 678 infants in Busia, Uganda, an area of high malaria transmission. We followed infants through 12 months of age and quantified protection against parasitemia and clinical disease. Results Symptomatic malaria incidence increased from 1.2 to 2.6 episodes per person-year between 0 and <6 months and between 6 and 12 months of age, while the monthly probability of asymptomatic parasitemia given infection decreased from 32% to 21%. Sickle cell trait (HbAS) was protective against symptomatic malaria (incidence rate ratio = 0.57 comparing HbAS vs hemoglobin AA (HbAA); 95% confidence interval, 0.44–0.74; P < .001), but age modified this relationship (Pint = <0.001), with nonlinear protection that waned between 0 and 9 months of age before increasing. Increasing age was associated with higher parasite densities at the time of infection and, in infants with HbAS, a reduced ability to tolerate high parasite densities without fever. Conclusions Age-dependent changes in HbAS protective efficacy in infancy were accompanied by differential loss of antiparasite and antidisease protection among HbAS and HbAA infants. This provides a framework for investigating the mechanisms that underlie infant protection against malaria. Clinical Trials Registration NCT02793622.
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Affiliation(s)
| | - Harriet Adrama
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Abel Kakuru
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Teddy Andra
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Richard Kajubi
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Melissa Conrad
- Department of Medicine, University of California, San Francisco, USA
| | | | - Tamara D Clark
- Department of Medicine, University of California, San Francisco, USA
| | - Moses Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda.,Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | | | - Grant Dorsey
- Department of Medicine, University of California, San Francisco, USA
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Gies S, Roberts SA, Diallo S, Lompo OM, Tinto H, Brabin BJ. Risk of malaria in young children after periconceptional iron supplementation. MATERNAL AND CHILD NUTRITION 2020; 17:e13106. [PMID: 33236840 PMCID: PMC7988873 DOI: 10.1111/mcn.13106] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 10/09/2020] [Accepted: 10/15/2020] [Indexed: 01/13/2023]
Abstract
This study in Burkina Faso investigated whether offspring of young mothers who had received weekly periconceptional iron supplementation in a randomised controlled trial were at increased risk of malaria. A child safety survey was undertaken in the peak month of malaria transmission towards the end of the trial to assess child iron biomarkers, nutritional status, anaemia and malaria outcomes. Antenatal iron biomarkers, preterm birth, fetal growth restriction and placental pathology for malaria and chorioamnionitis were assessed. Data were available for 180 babies surviving to the time of the survey when their median age was 9 months. Prevalence of maternal iron deficiency in the last trimester based on low body iron stores was 16%. Prevalence of active placental malaria infection was 24.8%, past infection 59% and chorioamnionitis 55.6%. Babies of iron supplemented women had lower median gestational age. Four out of five children ≥ 6 months were iron deficient, and 98% were anaemic. At 4 months malaria prevalence was 45%. Child iron biomarkers, anaemia and malaria outcomes did not differ by trial arm. Factors associated with childhood parasitaemia were third trimester C-reactive protein level (OR 2.1; 95% CI 1.1-3.9), active placental malaria (OR 5.8; 1.0-32.5, P = 0.042) and child body iron stores (OR 1.13; 1.04-1.23, P = 0.002). Chorioamnionitis was associated with reduced risk of child parasitaemia (OR 0.4; 0.1-1.0, P = 0.038). Periconceptional iron supplementation of young women did not alter body iron stores of their children. Higher child body iron stores and placental malaria increased risk of childhood parasitaemia.
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Affiliation(s)
- Sabine Gies
- Department of Biomedical Sciences, Prince Leopold Institute of Tropical Medicine, Antwerp, Belgium.,Medical Mission Institute, Wurzburg, Germany
| | - Stephen A Roberts
- Centre for Biostatistics, Division of Population Health, Health Services Research and Primary Care, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre (MAHSC), Manchester, UK
| | - Salou Diallo
- Institute for Research in Health Sciences-Clinical Research Unit of Nanoro (IRSS-URCN), Ouagadougou, Burkina Faso
| | - Olga M Lompo
- Service d'Anatomocytopathologie et de Médicine Légale, Centre Hospitalier Universitaire Yalgado Ouedraogo, Ouagadougou, Burkina Faso
| | - Halidou Tinto
- Institute for Research in Health Sciences-Clinical Research Unit of Nanoro (IRSS-URCN), Ouagadougou, Burkina Faso
| | - Bernard J Brabin
- Clinical Division, Liverpool School of Tropical Medicine, Liverpool, UK.,Institute of Infection and Global Health, University of Liverpool, Liverpool, UK.,Global Child Health Group, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
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Haanshuus CG, Mørch K, Blomberg B, Strøm GEA, Langeland N, Hanevik K, Mohn SC. Assessment of malaria real-time PCR methods and application with focus on low-level parasitaemia. PLoS One 2019; 14:e0218982. [PMID: 31276473 PMCID: PMC6611585 DOI: 10.1371/journal.pone.0218982] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 06/04/2019] [Indexed: 01/04/2023] Open
Abstract
In epidemiological surveys and surveillance the application of molecular tools is essential in detecting submicroscopic malaria. A genus-specific conventional cytochrome b (cytb) PCR has shown high sensitivity in field studies, detecting 70% submicroscopic malaria. The main objective of this study was to assess the conversion from conventional to real-time PCR testing both SYBR and probe protocols, and including quantitative (q) PCR. The protocols were assessed applying well-defined clinical patient material consisting of 33 positive and 80 negative samples. Sequencing of positive PCR products was performed. In addition, a sensitivity comparison of real-time PCR methods was done by including five relevant assays investigating the effect of amplification target and platform. Sensitivity was further examined using field material consisting of 111 P.falciparum positive samples from Tanzanian children (< 5 years), as well as using related patient data to assess the application of q-PCR with focus on low-level parasitaemia. Both the cytb SYBR and probe PCR protocols showed as high sensitivity and specificity as their conventional counterpart, except missing one P. malariae sample. The SYBR protocol was more sensitive and specific than using probe. Overall, choice of amplification target applied is relevant for achieving ultra-sensitivity, and using intercalating fluorescence dye rather than labelled hydrolysis probes is favourable. Application of q-PCR analysis in field projects is important for the awareness and understanding of low-level parasitaemia. For use in clinical diagnosis and epidemiological studies the highly sensitive and user-friendly cytb SYBR q-PCR method is a relevant tool. The genus-specific method has the advantage that species identification by sequencing can be performed as an alternative to species-specific PCR.
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Affiliation(s)
- Christel Gill Haanshuus
- Norwegian National Advisory Unit on Tropical Infectious Diseases, Department of Medicine, Haukeland University Hospital, Bergen, Norway
- * E-mail:
| | - Kristine Mørch
- Norwegian National Advisory Unit on Tropical Infectious Diseases, Department of Medicine, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Bjørn Blomberg
- Norwegian National Advisory Unit on Tropical Infectious Diseases, Department of Medicine, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Science, University of Bergen, Bergen, Norway
| | | | - Nina Langeland
- Norwegian National Advisory Unit on Tropical Infectious Diseases, Department of Medicine, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Science, University of Bergen, Bergen, Norway
- Haraldsplass Deaconess Hospital, Bergen, Norway
| | - Kurt Hanevik
- Norwegian National Advisory Unit on Tropical Infectious Diseases, Department of Medicine, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Stein Christian Mohn
- Norwegian National Advisory Unit on Tropical Infectious Diseases, Department of Medicine, Haukeland University Hospital, Bergen, Norway
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Jaenisch T, Heiss K, Fischer N, Geiger C, Bischoff FR, Moldenhauer G, Rychlewski L, Sié A, Coulibaly B, Seeberger PH, Wyrwicz LS, Breitling F, Loeffler FF. High-density Peptide Arrays Help to Identify Linear Immunogenic B-cell Epitopes in Individuals Naturally Exposed to Malaria Infection. Mol Cell Proteomics 2019; 18:642-656. [PMID: 30630936 PMCID: PMC6442360 DOI: 10.1074/mcp.ra118.000992] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 11/28/2018] [Indexed: 01/31/2023] Open
Abstract
High-density peptide arrays are an excellent means to profile anti-plasmodial antibody responses. Different protein intrinsic epitopes can be distinguished, and additional insights are gained, when compared with assays involving the full-length protein. Distinct reactivities to specific epitopes within one protein may explain differences in published results, regarding immunity or susceptibility to malaria. We pursued three approaches to find specific epitopes within important plasmodial proteins, (1) twelve leading vaccine candidates were mapped as overlapping 15-mer peptides, (2) a bioinformatical approach served to predict immunogenic malaria epitopes which were subsequently validated in the assay, and (3) randomly selected peptides from the malaria proteome were screened as a control. Several peptide array replicas were prepared, employing particle-based laser printing, and were used to screen 27 serum samples from a malaria-endemic area in Burkina Faso, West Africa. The immunological status of the individuals was classified as "protected" or "unprotected" based on clinical symptoms, parasite density, and age. The vaccine candidate screening approach resulted in significant hits in all twelve proteins and allowed us (1) to verify many known immunogenic structures, (2) to map B-cell epitopes across the entire sequence of each antigen and (3) to uncover novel immunogenic epitopes. Predicting immunogenic regions in the proteome of the human malaria parasite Plasmodium falciparum, via the bioinformatics approach and subsequent array screening, confirmed known immunogenic sequences, such as in the leading malaria vaccine candidate CSP and discovered immunogenic epitopes derived from hypothetical or unknown proteins.
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Affiliation(s)
- Thomas Jaenisch
- From the ‡Center for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Im Neuenheimer Feld 324, D 69120 Heidelberg, Germany;; §German Center for Infectious Disease Research, Heidelberg (DZIF);; ¶HEiKA - Heidelberg Karlsruhe Research Partnership, Heidelberg University, Karlsruhe Institute of Technology (KIT), Germany;.
| | - Kirsten Heiss
- From the ‡Center for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Im Neuenheimer Feld 324, D 69120 Heidelberg, Germany;; §German Center for Infectious Disease Research, Heidelberg (DZIF)
| | - Nico Fischer
- From the ‡Center for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Im Neuenheimer Feld 324, D 69120 Heidelberg, Germany;; §German Center for Infectious Disease Research, Heidelberg (DZIF);; ¶HEiKA - Heidelberg Karlsruhe Research Partnership, Heidelberg University, Karlsruhe Institute of Technology (KIT), Germany
| | - Carolin Geiger
- From the ‡Center for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Im Neuenheimer Feld 324, D 69120 Heidelberg, Germany;; §German Center for Infectious Disease Research, Heidelberg (DZIF)
| | - F Ralf Bischoff
- ‖German Cancer Research Center, Im Neuenheimer Feld 280, D 69120 Heidelberg, Germany
| | - Gerhard Moldenhauer
- ‖German Cancer Research Center, Im Neuenheimer Feld 280, D 69120 Heidelberg, Germany
| | - Leszek Rychlewski
- BioInfoBank Institute, Św. Marcin 80/82 lok. 355, 61-809 Poznań, Poland
| | - Ali Sié
- Centre de Recherche en Santé de Nouna, BP 02 Nouna, Rue Namory Keita, Burkina Faso
| | - Boubacar Coulibaly
- Centre de Recherche en Santé de Nouna, BP 02 Nouna, Rue Namory Keita, Burkina Faso
| | - Peter H Seeberger
- §§Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, D 14476 Potsdam, Germany
| | - Lucjan S Wyrwicz
- Department of Oncology and Radiotherapy, M Sklodowska Curie Memorial Cancer Center, Wawelska 15, 02-034 Warsaw, Poland
| | - Frank Breitling
- ‖‖Institute of Microstructure Technology, Karlsruhe Institute of Technology, Germany Hermann-von-Helmholtz-Platz 1, D 76344 Eggenstein-Leopoldshafen, Germany
| | - Felix F Loeffler
- ¶HEiKA - Heidelberg Karlsruhe Research Partnership, Heidelberg University, Karlsruhe Institute of Technology (KIT), Germany;; §§Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, D 14476 Potsdam, Germany;.
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Geostatistical analysis and mapping of malaria risk in children under 5 using point-referenced prevalence data in Ghana. Malar J 2019; 18:67. [PMID: 30871551 PMCID: PMC6419518 DOI: 10.1186/s12936-019-2709-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 03/06/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria remains a major challenge in sub-Saharan Africa and Ghana is not an exception. Effective malaria transmission control requires evidence-based targeting and utilization of resources. Disease risk mapping provides an effective and efficient tool for monitoring transmission and control efforts. The aim of this study is to analyse and map malaria risk in children under 5 years old, with the ultimate goal of identifying areas where control efforts can be targeted. METHODS Data collected from the 2016 Ghana demographic and health survey was analyzed. Binomial logistic regression was applied to examine the determinants of malaria risk among children. Model-based geostatistical methods were applied to analyze, predict and map malaria prevalence. RESULTS There is a significant association of malaria prevalence with area of residence (rural/urban), age, indoor residual spray use, social economic status and mother's education level. Overall, parasitaemia prevalence among children under 5 years old for the year 2016 is low albeit characterized by "hotspots" in specific areas. CONCLUSION The risk maps indicate the spatial heterogeneity of malaria prevalence. The high resolution maps can serve as an effective tool in the identification of locations that require targeted interventions by programme implementers; this is key and relevant for reducing malaria burden in Ghana.
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Ihantamalala FA, Rakotoarimanana FMJ, Ramiadantsoa T, Rakotondramanga JM, Pennober G, Rakotomanana F, Cauchemez S, Metcalf CJE, Herbreteau V, Wesolowski A. Spatial and temporal dynamics of malaria in Madagascar. Malar J 2018; 17:58. [PMID: 29391023 PMCID: PMC5796477 DOI: 10.1186/s12936-018-2206-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 01/24/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria is one of the primary health concerns in Madagascar. Based on the duration and intensity of transmission, Madagascar is divided into five epidemiological strata that range from low to mesoendemic transmission. In this study, the spatial and temporal dynamics of malaria within each epidemiological zone were studied. METHODS The number of reported cases of uncomplicated malaria from 112 health districts between 2010 and 2014 were compiled and analysed. First, a Standardized Incidence Ratio was calculated to detect districts with anomalous incidence compared to the stratum-level incidence. Building on this, spatial and temporal malaria clusters were identified throughout the country and their variability across zones and over time was analysed. RESULTS The incidence of malaria increased from 2010 to 2014 within each stratum. A basic analysis showed that districts with more than 50 cases per 1000 inhabitants are mainly located in two strata: East and West. Lower incidence values were found in the Highlands and Fringe zones. The standardization method revealed that the number of districts with a higher than expected numbers of cases increased through time and expanded into the Highlands and Fringe zones. The cluster analysis showed that for the endemic coastal region, clusters of districts migrated southward and the incidence of malaria was the highest between January and July with some variation within strata. CONCLUSION This study identified critical districts with low incidence that shifted to high incidence and district that were consistent clusters across each year. The current study provided a detailed description of changes in malaria epidemiology and can aid the national malaria programme to reduce and prevent the expansion of the disease by targeting the appropriate areas.
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Affiliation(s)
- Felana A Ihantamalala
- Epidemiology Unit, Institut Pasteur de Madagascar, Antananarivo, Madagascar
- UMR 228 ESPACE-DEV (IRD, UM2, UR, UAG), Saint-Pierre, Reunion, France
| | | | - Tanjona Ramiadantsoa
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI, USA
| | | | | | | | - Simon Cauchemez
- Mathematical Modelling of Infectious Diseases Unit, Institut Pasteur, 75015, Paris, France
- Centre National de la Recherche Scientifique, URA3012, 75015, Paris, France
- Centre of Bioinformatics, Biostatistics and Integrative Biology, Institut Pasteur, 75015, Paris, France
| | - Charlotte J E Metcalf
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA
- Woodrow Wilson School of Public Affairs, Princeton University, Princeton, NJ, USA
| | | | - Amy Wesolowski
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
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Stephens JK, Kyei-Baafour E, Dickson EK, Ofori JK, Ofori MF, Wilson ML, Quakyi IA, Akanmori BD. Effect of IPTp on Plasmodium falciparum antibody levels among pregnant women and their babies in a sub-urban coastal area in Ghana. Malar J 2017; 16:224. [PMID: 28549426 PMCID: PMC5446726 DOI: 10.1186/s12936-017-1857-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Accepted: 05/12/2017] [Indexed: 12/31/2022] Open
Abstract
Background Women exposed to Plasmodium infection develop antibodies and become semi-immune. This immunity is suppressed during pregnancy making both the pregnant woman and the foetus vulnerable to the adverse effects of malaria, particularly by Plasmodium falciparum. Intermittent preventive treatment of malaria in pregnancy (IPTp) with Sulfadoxine–pyrimethamine (SP) tablets is one of the current interventions to mitigate the effects of malaria on both the pregnant woman and the unborn child. The extent to which IPTp may interfere with the acquisition of protective immunity against pregnancy-associated malaria (PAM) is undefined in Ghana. Methods Three-hundred-and-twenty pregnant women were randomly enrolled at the antenatal clinic (ANC) in Madina, Accra. Venous blood samples were obtained at first ANC registration and at 4-week intervals (post-IPTp administration). Placental and cord blood samples were obtained at delivery and the infants were followed monthly for 6 months after birth. Anti-IgG and IgM antibodies against a crude antigen preparation and the glutamate-rich protein (GLURP) of P. falciparum were quantified by the enzyme-linked immunosorbent assay (ELISA). Results There was a general decline in the trend of mean concentrations of all the antibodies from enrolment to delivery. The levels of antibodies in cord blood and placenta were well correlated. Children did not show clinical signs of malaria at 6 months after birth. Conclusions IgG against both crude antigen and GLURP were present in placenta and cord blood and it is therefore concluded that there is a trend of declining antibody from enrolment to delivery and IPTp-SP may have reduced malaria exposure, however, this does not impact on the transfer of antibodies to the foetus in utero. The levels of maternal and cord blood antibodies at delivery showed no adverse implications on malaria among the children at 6 months. However, the quantum and quality of the antibody transferred needs further investigation to ensure that the infants are protected from severe episodes of malaria.
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Affiliation(s)
- Judith K Stephens
- Biological, Environmental and Occupational and Health Sciences Department, School of Public Health, College of Health Sciences, University of Ghana, P. O. Box LG 13, Legon, Accra, Ghana.
| | - Eric Kyei-Baafour
- Immunology Department Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P. O. Box LG 581, Legon, Accra, Ghana
| | - Emmanuel K Dickson
- Immunology Department Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P. O. Box LG 581, Legon, Accra, Ghana
| | - Jones K Ofori
- Biological, Environmental and Occupational and Health Sciences Department, School of Public Health, College of Health Sciences, University of Ghana, P. O. Box LG 13, Legon, Accra, Ghana
| | - Michael F Ofori
- Immunology Department Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P. O. Box LG 581, Legon, Accra, Ghana
| | - Mark L Wilson
- Department of Epidemiology, School of Public Health, The University of Michigan, 109 Observatory Street, Ann Arbor, MI, 48109-2029, USA
| | - Isabella A Quakyi
- Biological, Environmental and Occupational and Health Sciences Department, School of Public Health, College of Health Sciences, University of Ghana, P. O. Box LG 13, Legon, Accra, Ghana
| | - Bartholomew D Akanmori
- Immunology Department Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P. O. Box LG 581, Legon, Accra, Ghana.,Vaccine Research and Development, Immunization and Vaccines Development Cluster, Office of the Regional Director, WHO Regional Office for Africa, P. O. Box 06, Djoue, Brazzaville, Congo
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Guerra M, Neres R, Salgueiro P, Mendes C, Ndong-Mabale N, Berzosa P, de Sousa B, Arez AP. Plasmodium falciparum Genetic Diversity in Continental Equatorial Guinea before and after Introduction of Artemisinin-Based Combination Therapy. Antimicrob Agents Chemother 2017; 61:e02556-15. [PMID: 27795385 PMCID: PMC5192141 DOI: 10.1128/aac.02556-15] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 10/17/2016] [Indexed: 11/20/2022] Open
Abstract
Efforts to control malaria may affect malaria parasite genetic variability and drug resistance, the latter of which is associated with genetic events that promote mechanisms to escape drug action. The worldwide spread of drug resistance has been a major obstacle to controlling Plasmodium falciparum malaria, and thus the study of the origin and spread of associated mutations may provide some insights into the prevention of its emergence. This study reports an analysis of P. falciparum genetic diversity, focusing on antimalarial resistance-associated molecular markers in two socioeconomically different villages in mainland Equatorial Guinea. The present study took place 8 years after a previous one, allowing the analysis of results before and after the introduction of an artemisinin-based combination therapy (ACT), i.e., artesunate plus amodiaquine. Genetic diversity was assessed by analysis of the Pfmsp2 gene and neutral microsatellite loci. Pfdhps and Pfdhfr alleles associated with sulfadoxine-pyrimethamine (SP) resistance and flanking microsatellite loci were investigated, and the prevalences of drug resistance-associated point mutations of the Pfcrt, Pfmdr1, Pfdhfr, and Pfdhps genes were estimated. Further, to monitor the use of ACT, we provide the baseline prevalences of K13 propeller mutations and Pfmdr1 copy numbers. After 8 years, noticeable differences occurred in the distribution of genotypes conferring resistance to chloroquine and SP, and the spread of mutated genotypes differed according to the setting. Regarding artemisinin resistance, although mutations reported as being linked to artemisinin resistance were not present at the time, several single nucleotide polymorphisms (SNPs) were observed in the K13 gene, suggesting that closer monitoring should be maintained to prevent the possible spread of artemisinin resistance in Africa.
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Affiliation(s)
- Mónica Guerra
- Global Health and Tropical Medicine (GHTM), Instituto de Higiene e Medicina Tropical (IHMT), Universidade Nova de Lisboa (UNL), Lisbon, Portugal
| | - Rita Neres
- Global Health and Tropical Medicine (GHTM), Instituto de Higiene e Medicina Tropical (IHMT), Universidade Nova de Lisboa (UNL), Lisbon, Portugal
| | - Patrícia Salgueiro
- Global Health and Tropical Medicine (GHTM), Instituto de Higiene e Medicina Tropical (IHMT), Universidade Nova de Lisboa (UNL), Lisbon, Portugal
| | - Cristina Mendes
- Global Health and Tropical Medicine (GHTM), Instituto de Higiene e Medicina Tropical (IHMT), Universidade Nova de Lisboa (UNL), Lisbon, Portugal
| | - Nicolas Ndong-Mabale
- Centro de Referencia para el Control de Endemias, Instituto de Salud Carlos III, Bata, Equatorial Guinea
| | - Pedro Berzosa
- Centro Nacional de Medicina Tropical, Instituto de Salud Carlos III, Madrid, Spain
| | - Bruno de Sousa
- Faculdade de Psicologia e de Ciências da Educação, Universidade de Coimbra, Coimbra, Portugal
| | - Ana Paula Arez
- Global Health and Tropical Medicine (GHTM), Instituto de Higiene e Medicina Tropical (IHMT), Universidade Nova de Lisboa (UNL), Lisbon, Portugal
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Murungi LM, Sondén K, Odera D, Oduor LB, Guleid F, Nkumama IN, Otiende M, Kangoye DT, Fegan G, Färnert A, Marsh K, Osier FHA. Cord blood IgG and the risk of severe Plasmodium falciparum malaria in the first year of life. Int J Parasitol 2016; 47:153-162. [PMID: 27890694 PMCID: PMC5297353 DOI: 10.1016/j.ijpara.2016.09.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Revised: 08/31/2016] [Accepted: 09/03/2016] [Indexed: 01/18/2023]
Abstract
Severe malaria episodes are rare during the first few months of life. The rate of decay of cord blood IgG is inversely proportional to the starting concentration. Antibody dependent respiratory burst mediated by cord IgG protects from severe malaria during the first 6 months of infancy.
Young infants are less susceptible to severe episodes of malaria but the targets and mechanisms of protection are not clear. Cord blood antibodies may play an important role in mediating protection but many studies have examined their association with the outcome of infection or non-severe malaria. Here, we investigated whether cord blood IgG to Plasmodium falciparum merozoite antigens and antibody-mediated effector functions were associated with reduced odds of developing severe malaria at different time points during the first year of life. We conducted a case-control study of well-defined severe falciparum malaria nested within a longitudinal birth cohort of Kenyan children. We measured cord blood total IgG levels against five recombinant merozoite antigens and antibody function in the growth inhibition activity and neutrophil antibody-dependent respiratory burst assays. We also assessed the decay of maternal antibodies during the first 6 months of life. The mean antibody half-life range was 2.51 months (95% confidence interval (CI): 2.19–2.92) to 4.91 months (95% CI: 4.47–6.07). The rate of decline of maternal antibodies was inversely proportional to the starting concentration. The functional assay of antibody-dependent respiratory burst activity predicted significantly reduced odds of developing severe malaria during the first 6 months of life (Odds ratio (OR) 0.07, 95% CI: 0.007–0.74, P = 0.007). Identification of the targets of antibodies mediating antibody-dependent respiratory burst activity could contribute to the development of malaria vaccines that protect against severe episodes of malaria in early infancy.
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Affiliation(s)
- Linda M Murungi
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya.
| | - Klara Sondén
- Unit of Infectious Diseases, Department of Medicine, Solna, Karolinska Institutet, SE-171 76 Stockholm, Sweden
| | - Dennis Odera
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya
| | - Loureen B Oduor
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya
| | - Fatuma Guleid
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya
| | - Irene N Nkumama
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya
| | - Mark Otiende
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya
| | - David T Kangoye
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya; Centre National de Recherche et de Formation sur le Paludisme (CNRFP), 01 BP 2208, Ouagadougou 01, Burkina Faso
| | - Greg Fegan
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya
| | - Anna Färnert
- Unit of Infectious Diseases, Department of Medicine, Solna, Karolinska Institutet, SE-171 76 Stockholm, Sweden; Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Kevin Marsh
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya; African Academy of Sciences, P.O. Box 24916-00502, Nairobi, Kenya; Nuffield Department of Medicine, Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom
| | - Faith H A Osier
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya
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11
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Kakuru A, Natureeba P, Muhindo MK, Clark TD, Havlir DV, Cohan D, Dorsey G, Kamya MR, Ruel T. Malaria burden in a birth cohort of HIV-exposed uninfected Ugandan infants living in a high malaria transmission setting. Malar J 2016; 15:500. [PMID: 27756308 PMCID: PMC5070200 DOI: 10.1186/s12936-016-1568-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 10/07/2016] [Indexed: 11/13/2022] Open
Abstract
Background HIV-exposed, uninfected (HEU) infants suffer high morbidity and mortality in the first year of life compared to HIV-unexposed, uninfected (HUU) infants, but accurate data on the contribution of malaria are limited. Methods The incidence of febrile illnesses and malaria were evaluated in a birth cohort of HEU infants. Infants were prescribed daily trimethoprim–sulfamethoxazole (TS) prophylaxis from 6 weeks of age until exclusion of HIV-infection after cessation of breastfeeding. Infants were followed for all illnesses using passive surveillance and routine blood smears were done monthly. Malaria was diagnosed as a positive blood smear plus fever. Placental malaria was determined by histopathology, placental blood smear and PCR. Risk factors for time to first episode of malaria were assessed using a Cox proportional hazards model. Malaria incidence among HEU infants aged 6–12 months was compared to that in other cohorts of HEU and HUU infants from the same region. Results Among 361 HEU infants enrolled, 248 completed 12 months of follow-up resulting in 1562 episodes of febrile illness and 253 episodes of malaria after 305 person-years of follow-up. The incidence of febrile illness was 5.12 episodes per person-year (PPY), ranging from 4.13 episodes PPY in the first 4 months of life to 5.71 episodes PPY between 5 and 12 months of age. The overall malaria incidence was 0.83 episodes per person-year (PPY), increasing from 0.03 episodes PPY in the first 2 months of life to 2.00 episodes PPY between 11 and 12 months of age. There were no episodes of complicated malaria. The prevalence of asymptomatic parasitaemia was 1.2 % (19 of 1568 routine smears positive). Infants born to mothers with parasites detected from placental blood smears were at higher risk of malaria (hazard ratio = 4.51, P < 0.001). HEU infants in this study had a 2.4- to 3.5-fold lower incidence of malaria compared to HUU infants in other cohort studies from the same area. Conclusion The burden of malaria in this birth cohort of HEU infants living in a high-transmission setting and taking daily TS prophylaxis was relatively low. Alternative etiologies of fever should be considered in HEU-infants taking daily TS prophylaxis who present with fever. Trial Registration NCT00993031, registered 8 October, 2009
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Affiliation(s)
- Abel Kakuru
- Infectious Diseases Research Collaboration, Kampala, Uganda.
| | - Paul Natureeba
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Mary K Muhindo
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Tamara D Clark
- Department of Medicine, University of California, San Francisco, USA
| | - Diane V Havlir
- Department of Medicine, University of California, San Francisco, USA
| | - Deborah Cohan
- Department of Obstetrics and Gynecology, University of California, San Francisco, USA
| | - Grant Dorsey
- Department of Medicine, University of California, San Francisco, USA
| | - Moses R Kamya
- Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - Theodore Ruel
- Department of Pediatrics, University of California, San Francisco, USA
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Arnot DE, Jensen ATR. Antigenic Variation and the Genetics and Epigenetics of the PfEMP1 Erythrocyte Surface Antigens in Plasmodium falciparum Malaria. ADVANCES IN APPLIED MICROBIOLOGY 2016; 74:77-96. [PMID: 21459194 DOI: 10.1016/b978-0-12-387022-3.00007-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
How immunity to malaria develops remains one of the great unresolved issues in bio-medicine and resolution of its various paradoxes is likely to be the key to developing effective malaria vaccines. The basic epidemiological observations are; under conditions of intense natural transmission, humans do become immune to P. falciparum malaria, but this is a slow process requiring multiple disease episodes which many, particularly young children, do not survive. Adult survivors are immune to the symptoms of malaria, and unless pregnant, can control the growth of most or all new inoculations. Sterile immunity is not achieved and chronic parasitization of apparently healthy adults is the norm. In this article, we analyse the best understood malaria "antigenic variation" system, that based on Plasmodium falciparum's PfEMP1-type cytoadhesion antigens, and critically review recent literature on the function and control of this multi-gene family of parasite variable surface antigens.
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Affiliation(s)
- David E Arnot
- Centre for Medical Parasitology, Department of International Health, Immunology and Microbiology, Faculty of Health Sciences, University of Copenhagen, CSS Oester Farimagsgade 5, Copenhagen K, Denmark; Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), CSS Oester Farimagsgade 5, Copenhagen K, Denmark; Institute of Immunology and Infection Research, School of Biology, University of Edinburgh, Edinburgh, Scotland, United Kingdom
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Abstract
Malaria is one of the most serious infectious diseases with most of the severe disease
caused by Plasmodium falciparum (Pf). Naturally acquired immunity
develops over time after repeated infections and the development of antimalarial
antibodies is thought to play a crucial role. Neonates and young infants are relatively
protected from symptomatic malaria through mechanisms that are poorly understood. The
prevailing paradigm is that maternal antimalarial antibodies transferred to the fetus in
the last trimester of pregnancy protect the infant from early infections. These
antimalarial antibodies wane by approximately 6 months of age leaving the infant
vulnerable to malaria, however direct evidence supporting this epidemiologically based
paradigm is lacking. As infants are the target population for future malaria vaccines,
understanding how they begin to develop immunity to malaria and the gaps in their
responses is key. This review summarizes the antimalarial antibody responses detected in
infants and how they change over time. We focus primarily on Pf antibody responses and
will briefly mention Plasmodium vivax responses in infants.
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14
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Contrasting Patterns of Serologic and Functional Antibody Dynamics to Plasmodium falciparum Antigens in a Kenyan Birth Cohort. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2015; 23:104-16. [PMID: 26656119 PMCID: PMC4744923 DOI: 10.1128/cvi.00452-15] [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: 08/05/2015] [Accepted: 11/20/2015] [Indexed: 11/20/2022]
Abstract
IgG antibodies to Plasmodium falciparum are transferred from the maternal to fetal circulation during pregnancy, wane after birth, and are subsequently acquired in response to natural infection. We examined the dynamics of malaria antibody responses of 84 Kenyan infants from birth to 36 months of age by (i) serology, (ii) variant surface antigen (VSA) assay, (iii) growth inhibitory activity (GIA), and (iv) invasion inhibition assays (IIA) specific for merozoite surface protein 1 (MSP1) and sialic acid-dependent invasion pathway. Maternal antibodies in each of these four categories were detected in cord blood and decreased to their lowest level by approximately 6 months of age. Serologic antibodies to 3 preerythrocytic and 10 blood-stage antigens subsequently increased, reaching peak prevalence by 36 months. In contrast, antibodies measured by VSA, GIA, and IIA remained low even up to 36 months. Infants sensitized to P. falciparum in utero, defined by cord blood lymphocyte recall responses to malaria antigens, acquired antimalarial antibodies at the same rate as those who were not sensitized in utero, indicating that fetal exposure to malaria antigens did not affect subsequent infant antimalarial responses. Infants with detectable serologic antibodies at 12 months of age had an increased risk of P. falciparum infection during the subsequent 24 months. We conclude that serologic measures of antimalarial antibodies in children 36 months of age or younger represent biomarkers of malaria exposure rather than protection and that functional antibodies develop after 36 months of age in this population.
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15
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Battle KE, Guerra CA, Golding N, Duda KA, Cameron E, Howes RE, Elyazar IRF, Baird JK, Reiner RC, Gething PW, Smith DL, Hay SI. Global database of matched Plasmodium falciparum and P. vivax incidence and prevalence records from 1985-2013. Sci Data 2015; 2:150012. [PMID: 26306203 PMCID: PMC4540003 DOI: 10.1038/sdata.2015.12] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 03/02/2015] [Indexed: 01/06/2023] Open
Abstract
Measures of clinical incidence are necessary to help estimate the burden of a disease. Incidence is a metric not commonly measured in malariology because the longitudinal surveys required are costly and labour intensive. This database is an effort to collate published incidence records obtained using active case detection for Plasmodium falciparum and Plasmodium vivax malaria. The literature search methods, data abstraction procedures and data processing procedures are described here. A total of 1,680 spatio-temporally unique incidence records were collected for the database: 1,187 for P. falciparum and 493 for P. vivax. These data were gathered to model the relationship between clinical incidence and prevalence of infection and can be used for a variety of modelling exercises including the assessment of change in disease burden in relation to age and control interventions. The subset of data that have been used for such modelling exercises are described and identified.
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Affiliation(s)
- Katherine E Battle
- Spatial Ecology and Epidemiology Group, Tinbergen Building, Department of Zoology, University of Oxford , South Parks Road, Oxford OX1 3PS, UK
| | - Carlos A Guerra
- Sanaria Institute for Global Health and Tropical Medicine , Rockville, Maryland 20850, USA
| | - Nick Golding
- Spatial Ecology and Epidemiology Group, Tinbergen Building, Department of Zoology, University of Oxford , South Parks Road, Oxford OX1 3PS, UK
| | - Kirsten A Duda
- Spatial Ecology and Epidemiology Group, Tinbergen Building, Department of Zoology, University of Oxford , South Parks Road, Oxford OX1 3PS, UK
| | - Ewan Cameron
- Spatial Ecology and Epidemiology Group, Tinbergen Building, Department of Zoology, University of Oxford , South Parks Road, Oxford OX1 3PS, UK
| | - Rosalind E Howes
- Spatial Ecology and Epidemiology Group, Tinbergen Building, Department of Zoology, University of Oxford , South Parks Road, Oxford OX1 3PS, UK
| | - Iqbal R F Elyazar
- Eijkman-Oxford Clinical Research Unit , Jalan Diponegoro No 69, Jakarta 10430, Indonesia
| | - J Kevin Baird
- Eijkman-Oxford Clinical Research Unit , Jalan Diponegoro No 69, Jakarta 10430, Indonesia ; Nuffield Department of Medicine, Centre for Tropical Medicine, University of Oxford , Oxford OX3 7FZ, UK
| | - Robert C Reiner
- Indiana University School of Public Health , Bloomington, Indiana 47405, USA
| | - Peter W Gething
- Spatial Ecology and Epidemiology Group, Tinbergen Building, Department of Zoology, University of Oxford , South Parks Road, Oxford OX1 3PS, UK
| | - David L Smith
- Spatial Ecology and Epidemiology Group, Tinbergen Building, Department of Zoology, University of Oxford , South Parks Road, Oxford OX1 3PS, UK ; Fogarty International Center, National Institutes of Health , Bethesda, Maryland 20892, USA
| | - Simon I Hay
- Spatial Ecology and Epidemiology Group, Tinbergen Building, Department of Zoology, University of Oxford , South Parks Road, Oxford OX1 3PS, UK ; Fogarty International Center, National Institutes of Health , Bethesda, Maryland 20892, USA
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16
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Mara SE, Silué KD, Raso G, N'guetta SP, N'goran EK, Tanner M, Utzinger J, Ding XC. Genetic diversity of Plasmodium falciparum among school-aged children from the Man region, western Côte d'Ivoire. Malar J 2013; 12:419. [PMID: 24228865 PMCID: PMC3842749 DOI: 10.1186/1475-2875-12-419] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 11/12/2013] [Indexed: 11/24/2022] Open
Abstract
Background The genetic diversity of Plasmodium falciparum allows the molecular discrimination of otherwise microscopically identical parasites and the identification of individual clones in multiple infections. The study reported here investigated the P. falciparum multiplicity of infection (MOI) and genetic diversity among school-aged children in the Man region, western Côte d’Ivoire. Methods Blood samples from 292 children aged seven to 15 years were collected in four nearby villages located at altitudes ranging from 340 to 883 m above sea level. Giemsa-stained thick and thin blood films were prepared and examined under a microscope for P. falciparum prevalence and parasitaemia. MOI and genetic diversity of the parasite populations were investigated using msp2 typing by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Results Plasmodium falciparum prevalence and parasitaemia were both found to be significantly lower in the highest altitude village. Genotyping of the isolates revealed 25 potentially new msp2 alleles. MOI varied significantly across villages but did not correlate with altitude nor children’s age, and only to a limited extent with parasitaemia. An analysis of molecular variance (AMOVA) indicated that a small, but close to statistical significance (p = 0.07), fraction of variance occurs specifically between villages of low and high altitudes. Conclusions Higher altitude was associated with lower prevalence of P. falciparum but not with reduced MOI, suggesting that, in this setting, MOI is not a good proxy for transmission. The evidence for partially parted parasite populations suggests the existence of local geographical barriers that should be taken into account when deploying anti-malarial interventions.
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Affiliation(s)
| | | | | | | | | | | | | | - Xavier C Ding
- Département Environnement et Santé, Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303 Abidjan 01, Côte d'Ivoire.
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Staszewski V, Reece SE, O'Donnell AJ, Cunningham EJA. Drug treatment of malaria infections can reduce levels of protection transferred to offspring via maternal immunity. Proc Biol Sci 2012; 279:2487-96. [PMID: 22357264 PMCID: PMC3350664 DOI: 10.1098/rspb.2011.1563] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Accepted: 02/01/2012] [Indexed: 02/06/2023] Open
Abstract
Maternally transferred immunity can have a fundamental effect on the ability of offspring to deal with infection. However, levels of antibodies in adults can vary both quantitatively and qualitatively between individuals and during the course of infection. How infection dynamics and their modification by drug treatment might affect the protection transferred to offspring remains poorly understood. Using the rodent malaria parasite Plasmodium chabaudi, we demonstrate that curing dams part way through infection prior to pregnancy can alter their immune response, with major consequences for offspring health and survival. In untreated maternal infections, maternally transferred protection suppressed parasitaemia and reduced pup mortality by 75 per cent compared with pups from naïve dams. However, when dams were treated with anti-malarial drugs, pups received fewer maternal antibodies, parasitaemia was only marginally suppressed, and mortality risk was 25 per cent higher than for pups from dams with full infections. We observed the same qualitative patterns across three different host strains and two parasite genotypes. This study reveals the role that within-host infection dynamics play in the fitness consequences of maternally transferred immunity. Furthermore, it highlights a potential trade-off between the health of mothers and offspring suggesting that anti-parasite treatment may significantly affect the outcome of infection in newborns.
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Affiliation(s)
- Vincent Staszewski
- Centre for Infection Immunity and Evolution, University of Edinburgh, Edinburgh EH9 3JT, UK.
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18
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Kane EG, Taylor-Robinson AW. Prospects and Pitfalls of Pregnancy-Associated Malaria Vaccination Based on the Natural Immune Response to Plasmodium falciparum VAR2CSA-Expressing Parasites. Malar Res Treat 2012; 2011:764845. [PMID: 22363896 PMCID: PMC3272661 DOI: 10.4061/2011/764845] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 11/28/2011] [Accepted: 11/30/2011] [Indexed: 01/05/2023] Open
Abstract
Pregnancy-associated malaria, a manifestation of severe malaria, is the cause of up to 200,000 infant deaths a year, through the effects of placental insufficiency leading to growth restriction and preterm delivery. Development of a vaccine is one strategy for control. Plasmodium falciparum-infected red blood cells accumulate in the placenta through specific binding of pregnancy-associated parasite variants that express the VAR2CSA antigen to chondroitin sulphate A on the surface of syncytiotrophoblast cells. Parasite accumulation, accompanied by an inflammatory infiltrate, disrupts the cytokine balance of pregnancy with the potential to cause placental damage and compromise foetal growth. Multigravid women develop immunity towards VAR2CSA-expressing parasites in a gravidity-dependent manner which prevents unfavourable pregnancy outcomes. Although current vaccine design, targeting VAR2CSA antigens, has succeeded in inducing antibodies artificially, this candidate may not provide protection during the first trimester and may only protect those women living in areas endemic for malaria. It is concluded that while insufficient information about placental-parasite interactions is presently available to produce an effective vaccine, incremental progress is being made towards achieving this goal.
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Affiliation(s)
- Elizabeth G. Kane
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
- Faculty of Medicine, University of Liverpool, Liverpool L69 3GA, UK
| | - Andrew W. Taylor-Robinson
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
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19
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Severins M, Klinkenberg D, Heesterbeek H. How selection forces dictate the variant surface antigens used by malaria parasites. J R Soc Interface 2011; 9:246-60. [PMID: 21733875 DOI: 10.1098/rsif.2011.0239] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Red blood cells infected by the malaria parasite Plasmodium falciparum express variant surface antigens (VSAs) that evade host immunity and allow the parasites to persist in the human population. There exist many different VSAs and the differential expression of these VSAs is associated with the virulence (damage to the host) of the parasites. The aim of this study is to unravel the differences in the effect key selection forces have on parasites expressing different VSAs such that we can better understand how VSAs enable the parasites to adapt to changes in their environment (like control measures) and how this may impact the virulence of the circulating parasites. To this end, we have built an individual-based model that captures the main selective forces on malaria parasites, namely parasite competition, host immunity, host death and mosquito abundance at both the within- and between-host levels. VSAs are defined by the net growth rates they infer to the parasites and the model keeps track of the expression of, and antibody build-up against, each VSA in all hosts. Our results show an ordered acquisition of VSA-specific antibodies with host age, which causes a dichotomy between the more virulent VSAs that reach high parasitaemias but are restricted to young relatively non-immune hosts, and less virulent VSAs that do not reach such high parasitaemias but can infect a wider range of hosts. The outcome of a change in the parasite's environment in terms of parasite virulence depends on the exact balance between the selection forces, which sets the limiting factor for parasite survival. Parasites will evolve towards expressing more virulent VSAs when the limiting factor for parasite survival is the within-host parasite growth and the parasites are able to minimize this limitation by expressing more virulent VSAs.
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Affiliation(s)
- Maite Severins
- Theoretical Epidemiology, University of Utrecht, Yalelaan 7, 3584 CL Utrecht, The Netherlands.
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20
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Quelhas D, Jiménez A, Quintó L, Serra-Casas E, Mayor A, Cisteró P, Puyol L, Wilson DW, Richards JS, Nhampossa T, Macete E, Aide P, Mandomando I, Sanz S, Aponte JJ, Alonso PL, Beeson JG, Menéndez C, Dobaño C. IgG against Plasmodium falciparum variant surface antigens and growth inhibitory antibodies in Mozambican children receiving intermittent preventive treatment with sulfadoxine-pyrimethamine. Immunobiology 2011; 216:793-802. [DOI: 10.1016/j.imbio.2010.12.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Revised: 12/17/2010] [Accepted: 12/19/2010] [Indexed: 10/18/2022]
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21
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Amaratunga C, Lopera-Mesa TM, Brittain NJ, Cholera R, Arie T, Fujioka H, Keefer JR, Fairhurst RM. A role for fetal hemoglobin and maternal immune IgG in infant resistance to Plasmodium falciparum malaria. PLoS One 2011; 6:e14798. [PMID: 21532754 PMCID: PMC3075246 DOI: 10.1371/journal.pone.0014798] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Accepted: 01/25/2011] [Indexed: 11/30/2022] Open
Abstract
Background In Africa, infant susceptibility to Plasmodium falciparum malaria increases substantially as fetal hemoglobin (HbF) and maternal immune IgG disappear from circulation. During the first few months of life, however, resistance to malaria is evidenced by extremely low parasitemias, the absence of fever, and the almost complete lack of severe disease. This resistance has previously been attributed in part to poor parasite growth in HbF-containing red blood cells (RBCs). A specific role for maternal immune IgG in infant resistance to malaria has been hypothesized but not yet identified. Methods and Findings We found that P. falciparum parasites invade and develop normally in fetal (cord blood, CB) RBCs, which contain up to 95% HbF. However, these parasitized CB RBCs are impaired in their binding to human microvascular endothelial cells (MVECs), monocytes, and nonparasitized RBCs – cytoadherence interactions that have been implicated in the development of high parasite densities and the symptoms of malaria. Abnormal display of the parasite's cytoadherence antigen P. falciparum erythrocyte membrane protein-1 (PfEMP-1) on CB RBCs accounts for these findings and is reminiscent of that on HbC and HbS RBCs. IgG purified from the plasma of immune Malian adults almost completely abolishes the adherence of parasitized CB RBCs to MVECs. Conclusions Our data suggest a model of malaria protection in which HbF and maternal IgG act cooperatively to impair the cytoadherence of parasitized RBCs in the first few months of life. In highly malarious areas of Africa, an infant's contemporaneous expression of HbC or HbS and development of an immune IgG repertoire may effectively reconstitute the waning protective effects of HbF and maternal immune IgG, thereby extending the malaria resistance of infancy into early childhood.
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Affiliation(s)
- Chanaki Amaratunga
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Tatiana M. Lopera-Mesa
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Nathaniel J. Brittain
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Rushina Cholera
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Takayuki Arie
- Department of Physics and Electronics, School of Engineering, Osaka Prefecture University, Osaka, Japan
| | - Hisashi Fujioka
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Jeffrey R. Keefer
- Division of Pediatric Hematology, Department of Pediatrics, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
| | - Rick M. Fairhurst
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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Surface co-expression of two different PfEMP1 antigens on single plasmodium falciparum-infected erythrocytes facilitates binding to ICAM1 and PECAM1. PLoS Pathog 2010; 6:e1001083. [PMID: 20824088 PMCID: PMC2932717 DOI: 10.1371/journal.ppat.1001083] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Accepted: 07/29/2010] [Indexed: 11/24/2022] Open
Abstract
The Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) antigens play a major role in cytoadhesion of infected erythrocytes (IE), antigenic variation, and immunity to malaria. The current consensus on control of variant surface antigen expression is that only one PfEMP1 encoded by one var gene is expressed per cell at a time. We measured var mRNA transcript levels by real-time Q-PCR, analysed var gene transcripts by single-cell FISH and directly compared these with PfEMP1 antigen surface expression and cytoadhesion in three different antibody-selected P. falciparum 3D7 sub-lines using live confocal microscopy, flow cytometry and in vitro adhesion assays. We found that one selected parasite sub-line simultaneously expressed two different var genes as surface antigens, on single IE. Importantly, and of physiological relevance to adhesion and malaria pathogenesis, this parasite sub-line was found to bind both CD31/PECAM1 and CD54/ICAM1 and to adhere twice as efficiently to human endothelial cells, compared to infected cells having only one PfEMP1 variant on the surface. These new results on PfEMP1 antigen expression indicate that a re-evaluation of the molecular mechanisms involved in P. falciparum adhesion and of the accepted paradigm of absolutely mutually exclusive var gene transcription is required. Plasmodium falciparum is the most pathogenic human malaria parasite and its virulence has been linked to its capacity to express different adhesion proteins that enable the developing parasitized erythrocyte to bind to capillaries of the host, thereby avoiding removal by the spleen. Each parasite has approximately 60 genes encoding different versions of this adhesion protein, and a switch in surface display of these proteins enables the parasite to evade the immune system. Here we show that different variants of these binding proteins can be found expressed simultaneously on single infected red blood cells mediating binding to different endothelial receptors.
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Ndam NT, Deloron P. Molecular aspects of Plasmodium falciparum Infection during pregnancy. J Biomed Biotechnol 2010; 2007:43785. [PMID: 17641725 PMCID: PMC1906705 DOI: 10.1155/2007/43785] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2006] [Accepted: 03/21/2007] [Indexed: 11/17/2022] Open
Abstract
Cytoadherence of Plasmodium-falciparum-parasitized red blood cells (PRBCs) to host receptors is the key phenomenon in the pathological process of the malaria disease. Some of these interactions can originate poor outcomes responsible for 1 to 3 million annual deaths mostly occurring among children in sub-Saharan Africa. Pregnancy-associated malaria (PAM) represents an important exception of the disease occurring at adulthood in malaria endemic settings. Consequences of this are shared between the mother (maternal anemia) and the baby (low birth weight and infant mortality). Demonstrating that parasites causing PAM express specific variant surface antigens (VSA(PAM)), including the P. falciparum erythrocyte membrane protein 1 (P f EMP1) variant VAR2CSA, that are targets for protective immunity has strengthened the possibility for the development of PAM-specific vaccine. In this paper, we review the molecular basis of malaria pathogenesis attributable to the erythrocyte stages of the parasites, and findings supporting potential anti-PAM vaccine components evidenced in PAM.
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Affiliation(s)
- Nicaise Tuikue Ndam
- UR 010, Laboratoire de Parasitologie, Institut de Recherche pour le Développement, Université Paris Descartes, IFR 71, 4 avenue de l'Observatoire, 75006 Paris, France
- *Nicaise Tuikue Ndam:
| | - Philippe Deloron
- UR 010, Laboratoire de Parasitologie, Institut de Recherche pour le Développement, Université Paris Descartes, IFR 71, 4 avenue de l'Observatoire, 75006 Paris, France
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Abstract
HIV and malaria kill millions of people every year. They share a common geographic distribution, and both cause far more disease and death in sub-Saharan Africa than they do in the rest of the world. Many epidemiologic studies have suggested that HIV and malaria coexist independently, but some recent reports describe synergistic interactions between them. People living with HIV infection who do not have pre-existing immunity to malaria experience a marked increase in malaria severity. But for those who have acquired immunity through natural exposure to malaria, HIV-related immunosuppression is associated with only a modest increase in clinical malaria, which may be explained in part by more frequent nonmalaria febrile episodes. The effect of malaria infection on HIV disease progression due to increased viral replication may be important but has not yet been fully explored.
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Affiliation(s)
- Miriam K Laufer
- Center for Vaccine Development, University of Maryland School of Medicine, 685 W. Baltimore Street, HSF-1 Room 480, Baltimore, MD 21201, USA
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25
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Joergensen LM, Salanti A, Dobrilovic T, Barfod L, Hassenkam T, Theander TG, Hviid L, Arnot DE. The kinetics of antibody binding to Plasmodium falciparum VAR2CSA PfEMP1 antigen and modelling of PfEMP1 antigen packing on the membrane knobs. Malar J 2010; 9:100. [PMID: 20403153 PMCID: PMC2868858 DOI: 10.1186/1475-2875-9-100] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Accepted: 04/19/2010] [Indexed: 11/25/2022] Open
Abstract
Background Infected humans make protective antibody responses to the PfEMP1 adhesion antigens exported by Plasmodium falciparum parasites to the erythrocyte membrane, but little is known about the kinetics of this antibody-receptor binding reaction or how the topology of PfEMP1 on the parasitized erythrocyte membrane influences antibody association with, and dissociation from, its antigenic target. Methods A Quartz Crystal Microbalance biosensor was used to measure the association and dissociation kinetics of VAR2CSA PfEMP1 binding to human monoclonal antibodies. Immuno-fluorescence microscopy was used to visualize antibody-mediated adhesion between the surfaces of live infected erythrocytes and atomic force microscopy was used to obtain higher resolution images of the membrane knobs on the infected erythrocyte to estimate knob surface areas and model VAR2CSA packing density on the knob. Results Kinetic analysis indicates that antibody dissociation from the VAR2CSA PfEMP1 antigen is extremely slow when there is a high avidity interaction. High avidity binding to PfEMP1 antigens on the surface of P. falciparum-infected erythrocytes in turn requires bivalent cross-linking of epitopes positioned within the distance that can be bridged by antibody. Calculations of the surface area of the knobs and the possible densities of PfEMP1 packing on the knobs indicate that high-avidity cross-linking antibody reactions are constrained by the architecture of the knobs and the large size of PfEMP1 molecules. Conclusions High avidity is required to achieve the strongest binding to VAR2CSA PfEMP1, but the structures that display PfEMP1 also tend to inhibit cross-linking between PfEMP1 antigens, by holding many binding epitopes at distances beyond the 15-18 nm sweep radius of an antibody. The large size of PfEMP1 will also constrain intra-knob cross-linking interactions. This analysis indicates that effective vaccines targeting the parasite's vulnerable adhesion receptors should primarily induce strongly adhering, high avidity antibodies whose association rate constant is less important than their dissociation rate constant.
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Affiliation(s)
- Lars M Joergensen
- Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health Sciences, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), CSS Øster Farimagsgade 5, Building 22 & 23, Postbox 2099, 1014 Copenhagen K, Denmark.
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Rogerson SJ. Malaria in pregnancy and the newborn. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 659:139-52. [PMID: 20204762 DOI: 10.1007/978-1-4419-0981-7_12] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Stephen J Rogerson
- Department of Medicine (RMH/WH), Post Office Royal Melbourne Hospital, Parkville, VIC, Australia.
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27
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Brooker S, Kolaczinski JH, Gitonga CW, Noor AM, Snow RW. The use of schools for malaria surveillance and programme evaluation in Africa. Malar J 2009; 8:231. [PMID: 19840372 PMCID: PMC2768743 DOI: 10.1186/1475-2875-8-231] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Accepted: 10/19/2009] [Indexed: 11/10/2022] Open
Abstract
Effective malaria control requires information on both the geographical distribution of malaria risk and the effectiveness of malaria interventions. The current standard for estimating malaria infection and impact indicators are household cluster surveys, but their complexity and expense preclude frequent and decentralized monitoring. This paper reviews the historical experience and current rationale for the use of schools and school children as a complementary, inexpensive framework for planning, monitoring and evaluating malaria control in Africa. Consideration is given to (i) the selection of schools; (ii) diagnosis of infection in schools; (iii) the representativeness of schools as a proxy of the communities they serve; and (iv) the increasing need to evaluate interventions delivered through schools. Finally, areas requiring further investigation are highlighted.
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Affiliation(s)
- Simon Brooker
- Malaria Public Health & Epidemiology Group, Centre for Geographic Medicine Research - Coast, Kenya Medical Research Institute-Wellcome Trust Research Programme, Nairobi, Kenya.
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28
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Abstract
Lars Hviid discusses a research article in PLoS Medicine that explores whether prenatal exposure to malaria is associated with increased susceptibility to malarial infection and anemia in infancy.
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29
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Stephens R, Ndungu FM, Langhorne J. Germinal centre and marginal zone B cells expand quickly in a second Plasmodium chabaudi malaria infection producing mature plasma cells. Parasite Immunol 2009; 31:20-31. [PMID: 19121080 PMCID: PMC2680269 DOI: 10.1111/j.1365-3024.2008.01066.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Antibodies and B cells are critical in the protective immune response to the blood stage of the malaria parasite, Plasmodium chabaudi. However, little is known about the development of memory B cells and their differentiation into plasma cells during infection or after re-infection. Here we have shown that B cells with phenotypic characteristics of memory cells (CD19+IgD− CD38+, IgG1+) are generated in a primaryPlasmodium chabaudi chabaudi infection of mice. In addition, we observed that germinal centre cells (CD19+, GL7+, MHCIIhi) and Marginal Zone B cells (CD19+CD23−IgD−) show faster expansion on re-infection than in the primary, though other subsets do not. Interestingly, though both IgM− and IgM+ memory cells are produced, IgM+ memory cells do not expand on second infection. The second infection quickly produced mature bone marrow plasma cells (intracellular Ighi, CD138hi, CD9+, B220−), compared to primary infection; which generates a very large population of immature splenic plasma cells (B220+). This analysis suggests that a memory B cell population is generated after a single infection of malaria, which on re-infection responds quickly producing germinal centres and generating long-lived plasma cells making the second encounter with parasite more efficient.
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Affiliation(s)
- R Stephens
- National Institute for Medical Research, Division of Parasitology, London, UK
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30
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Differences in human antibody reactivity to Plasmodium falciparum variant surface antigens are dependent on age and malaria transmission intensity in northeastern Tanzania. Infect Immun 2008; 76:2706-14. [PMID: 18250179 DOI: 10.1128/iai.01401-06] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plasmodium falciparum variant surface antigens (VSA) are involved in the pathogenesis of malaria. Immunoglobulin G (IgG) with specificity for VSA (anti-VSA IgG) is therefore considered important for acquired immunity. To better understand the nature and dynamics of variant-specific IgG responses at population level, we conducted an immunoepidemiological study in nearby communities in northeastern Tanzania, situated at different altitudes and therefore exposed to different levels of P. falciparum transmission intensity. Samples of plasma and infected red blood cells (IRBC) were collected from 759 individuals aged 0 to 19 years. Plasma levels of IgG with specificity for VSA expressed by a panel of different parasite isolates were measured by flow cytometry, while the ability of plasma to inhibit IRBC adhesion to CD36 was examined in cellular assays. The level and repertoire of the heterologous anti-VSA IgG response developed dramatically in individuals at 1 to 2 years of age in the high-transmission area, reaching a maximum level at around 10 years of age; only a modest further increase was observed among older children and adults. In contrast, at lower levels of malaria transmission, anti-VSA IgG levels were lower and the repertoire was more narrow, and similar age- and transmission-dependent differences were observed with regard to the ability of the plasma samples to inhibit adhesion of IRBC to CD36. These differences indicate a strong and dynamic relationship between malaria exposure and functional characteristics of the variant-specific antibody response, which is likely to be important for protection against malaria.
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Rogerson SJ, Mwapasa V, Meshnick SR. Malaria in Pregnancy: Linking Immunity and Pathogenesis to Prevention. Am J Trop Med Hyg 2007. [DOI: 10.4269/ajtmh.77.6.suppl.14] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Stephen J. Rogerson
- Department of Medicine (RMH/WH), The University of Melbourne, Royal Melbourne Hospital, Australia; Department of Community Health, College of Medicine, University of Malawi, Blantyre, Malawi; Department of Epidemiology, Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina
| | - Victor Mwapasa
- Department of Medicine (RMH/WH), The University of Melbourne, Royal Melbourne Hospital, Australia; Department of Community Health, College of Medicine, University of Malawi, Blantyre, Malawi; Department of Epidemiology, Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina
| | - Steven R. Meshnick
- Department of Medicine (RMH/WH), The University of Melbourne, Royal Melbourne Hospital, Australia; Department of Community Health, College of Medicine, University of Malawi, Blantyre, Malawi; Department of Epidemiology, Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina
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dalla Martha RC, Tada MS, Ferreira RGDM, da Silva LHP, Wunderlich G. Microsatellite characterization of Plasmodium falciparum from symptomatic and non-symptomatic infections from the Western Amazon reveals the existence of non-symptomatic infection-associated genotypes. Mem Inst Oswaldo Cruz 2007; 102:293-8. [PMID: 17568933 DOI: 10.1590/s0074-02762007005000044] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2006] [Accepted: 04/18/2007] [Indexed: 01/19/2023] Open
Abstract
In Western Amazon areas with perennial malaria transmission, long term residents frequently develop partial immunity to malarial infection caused either by Plasmodium falciparum or P. vivax, resulting in a considerable number of non-symptomatically infected individuals. For yet unknown reasons, these individuals sporadically develop symptomatic malaria. In order to identify if determined parasite genotypes, defined by a combination of eleven microsatellite markers, were associated to different outcomes--symptomatic or asymptomatic malaria--we analyzed infecting P. falciparum parasites in a suburban riverine population. Despite of detecting a high degree of diversity in the analyzed samples, several microsatellite marker alleles appeared accumulated in parasites from non-symptomatic infections. This result may be interpreted that a number of microsatellites, which are not directly related to antigenic features, could be associated to the outcome of malarial infection. The result may also point to a low frequency of recombinatorial events which otherwise would dissociate genes under strong immune pressure from the relatively neutral microsatellite loci.
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Kobbe R, Kreuzberg C, Adjei S, Thompson B, Langefeld I, Thompson PA, Abruquah HH, Kreuels B, Ayim M, Busch W, Marks F, Amoah K, Opoku E, Meyer CG, Adjei O, May J. A Randomized Controlled Trial of Extended Intermittent Preventive Antimalarial Treatment in Infants. Clin Infect Dis 2007; 45:16-25. [PMID: 17554695 DOI: 10.1086/518575] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Accepted: 02/15/2007] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Intermittent preventive antimalarial treatment in infants (IPTi) with sulfadoxine-pyrimethamine reduces falciparum malaria and anemia but has not been evaluated in areas with intense perennial malaria transmission. It is unknown whether an additional treatment in the second year of life prolongs protection. METHODS A randomized, double-blinded, placebo-controlled trial with administration of sulfadoxine-pyrimethamine therapy at 3, 9, and 15 months of age was conducted with 1070 children in an area in Ghana where malaria is holoendemic. Participants were monitored for 21 months after recruitment through active follow-up visits and passive case detection. The primary end point was malaria incidence, and additional outcome measures were anemia, outpatient visits, hospital admissions, and mortality. Stratified analyses for 6-month periods after each treatment were performed. RESULTS Protective efficacy against malaria episodes was 20% (95% confidence interval [CI], 11%-29%). The frequency of malaria episodes was reduced after the first 2 sulfadoxine-pyrimethamine applications (protective efficacy, 23% [95% CI, 6%-36%] after the first dose and 17% [95% CI, 1%-30%] after the second dose). After the third treatment at month 15, however, no protection was achieved. Protection against the first or single anemia episode was only significant after the first IPTi dose (protective efficacy, 30%; 95% CI, 5%-49%). The number of anemia episodes increased after the last IPTi dose (protective efficacy, -24%; 95% CI, -50% to -2%). CONCLUSION In an area of intense perennial malaria transmission, sulfadoxine-pyrimethamine-based IPTi conferred considerably lower protection than reported in areas where the disease is moderately or seasonally endemic. Protective efficacy is age-dependent, and extension of IPTi into the second year of life does not provide any benefit.
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Affiliation(s)
- Robin Kobbe
- Infectious Disease Epidemiology Group, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
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Cornelie S, Remoue F, Doucoure S, NDiaye T, Sauvage FX, Boulanger D, Simondon F. An insight into immunogenic salivary proteins of Anopheles gambiae in African children. Malar J 2007; 6:75. [PMID: 17550586 PMCID: PMC1891310 DOI: 10.1186/1475-2875-6-75] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Accepted: 06/05/2007] [Indexed: 12/01/2022] Open
Abstract
Background During blood feeding, the mosquito injects saliva into the vertebrate host. This saliva contains bioactive components which may play a role in pathogen transmission and in host-vector relationships by inducing an immune response in the vertebrate host. The evaluation of human immune responses to arthropod bites might also represent a research direction for assessing individual exposure to the bite of a malaria vector. Methods The present study examined the antibody (Ab) IgG response during the season of exposure to Anopheles gambiae bites in young children living in a malaria endemic area. Immunoblots were performed with An. gambiae saliva to detect anti-saliva Ab bands and the evolution of immunogenic bands at the peak of, and following, the transmission period. Results The results showed that anti-Anopheles Ab was directed against a limited number of salivary proteins (175, 115, 72 and 30 kDa bands). Specific IgG responses to mosquito salivary proteins were variable among exposed individuals; nevertheless, two major bands (175 and 72 kDa) were observed in all immune-responder children. Analysis of the intensity of immunogenic bands revealed that IgG levels against the 175 kDa band were significantly higher during the peak period compared to the end period malaria transmission. Conclusion This preliminary work supports the potential of using anti-saliva immune responses as a measure of exposure to Anopheles bites. The use of immunoblots coupled with evaluation of band intensity could be an adequate tool for distinguishing immunogenic salivary proteins as candidate markers of bite exposure. Furthermore, this study may open the way to design new epidemiological tools for evaluating the risk of malaria exposure.
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Affiliation(s)
- Sylvie Cornelie
- Unité de Recherche Epidemiologie et Prevention (UR024), Centre IRD de Montpellier, BP 64501,911 avenue Agropolis, 34394 Montpellier cedex 5, France
| | - Franck Remoue
- Unité de Recherche Epidemiologie et Prevention (UR024), Campus IRD de Hann, BP1386, Route des Pères Maristes, CP 18524, Dakar, Sénégal
| | - Souleymane Doucoure
- Unité de Recherche Epidemiologie et Prevention (UR024), Campus IRD de Hann, BP1386, Route des Pères Maristes, CP 18524, Dakar, Sénégal
| | - Tofene NDiaye
- Unité de Recherche Epidemiologie et Prevention (UR024), Campus IRD de Hann, BP1386, Route des Pères Maristes, CP 18524, Dakar, Sénégal
| | - Francois-Xavier Sauvage
- UMR Sciences pour l'Œnologie, INRA Centre de Montpellier, 2 place Viala 34060 Montpellier cedex 1, France
| | - Denis Boulanger
- Unité de Recherche Epidemiologie et Prevention (UR024), Campus IRD de Hann, BP1386, Route des Pères Maristes, CP 18524, Dakar, Sénégal
| | - Francois Simondon
- Unité de Recherche Epidemiologie et Prevention (UR024), Centre IRD de Montpellier, BP 64501,911 avenue Agropolis, 34394 Montpellier cedex 5, France
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Rogerson SJ, Hviid L, Duffy PE, Leke RFG, Taylor DW. Malaria in pregnancy: pathogenesis and immunity. THE LANCET. INFECTIOUS DISEASES 2007; 7:105-17. [PMID: 17251081 DOI: 10.1016/s1473-3099(07)70022-1] [Citation(s) in RCA: 362] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Understanding of the biological basis for susceptibility to malaria in pregnancy was recently advanced by the discovery that erythrocytes infected with Plasmodium falciparum accumulate in the placenta through adhesion to molecules such as chondroitin sulphate A. Antibody recognition of placental infected erythrocytes is dependent on sex and gravidity, and could protect from malaria complications. Moreover, a conserved parasite gene-var2csa-has been associated with placental malaria, suggesting that its product might be an appropriate vaccine candidate. By contrast, our understanding of placental immunopathology and how this contributes to anaemia and low birthweight remains restricted, although inflammatory cytokines produced by T cells, macrophages, and other cells are clearly important. Studies that unravel the role of host response to malaria in pathology and protection in the placenta, and that dissect the relation between timing of infection and outcome, could allow improved targeting of preventive treatments and development of a vaccine for use in pregnant women.
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Affiliation(s)
- Stephen J Rogerson
- Department of Medicine, University of Melbourne, Parkville, Victoria, Australia.
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36
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Magistrado PA, Lusingu J, Vestergaard LS, Lemnge M, Lavstsen T, Turner L, Hviid L, Jensen ATR, Theander TG. Immunoglobulin G antibody reactivity to a group A Plasmodium falciparum erythrocyte membrane protein 1 and protection from P. falciparum malaria. Infect Immun 2007; 75:2415-20. [PMID: 17283085 PMCID: PMC1865733 DOI: 10.1128/iai.00951-06] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Variant surface antigens (VSA) on the surface of Plasmodium falciparum-infected red blood cells play a major role in the pathogenesis of malaria and are key targets for acquired immunity. The best-characterized VSA belong to the P. falciparum erythrocyte membrane protein 1 (PfEMP1) family. In areas where P. falciparum is endemic, parasites causing severe malaria and malaria in young children with limited immunity tend to express semiconserved PfEMP1 molecules encoded by group A var genes. Here we investigated antibody responses of Tanzanians who were 0 to 19 years old to PF11_0008, a group A PfEMP1. PF11_0008 has previously been found to be highly transcribed in a nonimmune Dutch volunteer experimentally infected with NF54 parasites. A high proportion of the Tanzanian donors had antibodies against recombinant PF11_0008 domains, and in children who were 4 to 9 years old the presence of antibodies to the PF11_0008 CIDR2beta domain was associated with reduced numbers of malaria episodes. These results indicate that homologues of PF11_0008 are present in P. falciparum field isolates and suggest that PF11_0008 CIDR2beta-reactive antibodies might be involved in protection against malaria episodes.
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Affiliation(s)
- Pamela A Magistrado
- Centre for Medical Parasitology at Department of Medical Microbiology and Immunology, University of Copenhagen, Denmark.
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Joergensen L, Vestergaard LS, Turner L, Magistrado P, Lusingu JP, Lemnge M, Theander TG, Jensen ATR. 3D7-DerivedPlasmodium falciparumErythrocyte Membrane Protein 1 Is a Frequent Target of Naturally Acquired Antibodies Recognizing Protein Domains in a Particular Pattern Independent of Malaria Transmission Intensity. THE JOURNAL OF IMMUNOLOGY 2006; 178:428-35. [PMID: 17182581 DOI: 10.4049/jimmunol.178.1.428] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Protection against Plasmodium falciparum malaria is largely mediated by IgG against surface Ags such as the erythrocyte membrane protein 1 family (PfEMP1) responsible for antigenic variation and sequestration of infected erythrocytes. PfEMP1 molecules can be divided into groups A, B/A, B, C, and B/C. We have previously suggested that expression of groups A and B/A PfEMP1 is associated with severe disease and that Abs to these molecules are acquired earlier in life than Abs to PfEMP1 belonging to groups B, B/C, and C PfEMP1. In this study, we compared the acquisition of IgG to 20 rPfEMP1 domains derived from 3D7 in individuals living under markedly different malaria transmission intensity and were unable to find differences in the Ab acquisition rate to PfEMP1 of different groupings (A, B, or C) or domain type (alpha, beta, gamma, delta, epsilon, or x). Abs were acquired early in life in individuals living in the high transmission village and by the age of 2-4 years most individuals had Abs against most constructs. This level of reactivity was found at the age of 10-20 years in the medium transmission village and was never reached by individuals living under low transmission. Nevertheless, the sequence by which individuals acquired Abs to particular constructs was largely the same in the three villages. This indicates that the pattern of PfEMP1 expression by parasites transmitted at the different sites was similar, suggesting that PfEMP1 expression is nonrandom and shaped by host-parasite relationship factors operating at all transmission intensities.
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Affiliation(s)
- Louise Joergensen
- Centre for Medical Parasitology, Department of Medical Microbiology and Immunology, University of Copenhagen and Copenhagen University Hospital, Copenhagen, Denmark
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38
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Dahlbäck M, Rask TS, Andersen PH, Nielsen MA, Ndam NT, Resende M, Turner L, Deloron P, Hviid L, Lund O, Pedersen AG, Theander TG, Salanti A. Epitope mapping and topographic analysis of VAR2CSA DBL3X involved in P. falciparum placental sequestration. PLoS Pathog 2006; 2:e124. [PMID: 17112315 PMCID: PMC1636682 DOI: 10.1371/journal.ppat.0020124] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2006] [Accepted: 10/10/2006] [Indexed: 11/19/2022] Open
Abstract
Pregnancy-associated malaria is a major health problem, which mainly affects primigravidae living in malaria endemic areas. The syndrome is precipitated by accumulation of infected erythrocytes in placental tissue through an interaction between chondroitin sulphate A on syncytiotrophoblasts and a parasite-encoded protein on the surface of infected erythrocytes, believed to be VAR2CSA. VAR2CSA is a polymorphic protein of approximately 3,000 amino acids forming six Duffy-binding-like (DBL) domains. For vaccine development it is important to define the antigenic targets for protective antibodies and to characterize the consequences of sequence variation. In this study, we used a combination of in silico tools, peptide arrays, and structural modeling to show that sequence variation mainly occurs in regions under strong diversifying selection, predicted to form flexible loops. These regions are the main targets of naturally acquired immunoglobulin gamma and accessible for antibodies reacting with native VAR2CSA on infected erythrocytes. Interestingly, surface reactive anti-VAR2CSA antibodies also target a conserved DBL3X region predicted to form an alpha-helix. Finally, we could identify DBL3X sequence motifs that were more likely to occur in parasites isolated from primi- and multigravidae, respectively. These findings strengthen the vaccine candidacy of VAR2CSA and will be important for choosing epitopes and variants of DBL3X to be included in a vaccine protecting women against pregnancy-associated malaria.
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MESH Headings
- Amino Acid Motifs
- Amino Acid Sequence
- Animals
- Antibodies, Protozoan/immunology
- Antigens, Protozoan/genetics
- Antigens, Protozoan/immunology
- Antigens, Protozoan/metabolism
- B-Lymphocytes/immunology
- Binding, Competitive
- Chondroitin Sulfates/metabolism
- Epitope Mapping
- Female
- Genetic Variation
- Humans
- Malaria, Falciparum/physiopathology
- Models, Molecular
- Molecular Sequence Data
- Molecular Structure
- Parity
- Placenta/parasitology
- Plasmodium falciparum/immunology
- Pregnancy
- Protein Structure, Tertiary
- Protozoan Proteins/genetics
- Protozoan Proteins/immunology
- Protozoan Proteins/metabolism
- Receptors, Cell Surface/immunology
- Receptors, Cell Surface/metabolism
- Recombinant Proteins/genetics
- Recombinant Proteins/immunology
- Recombinant Proteins/metabolism
- Recombination, Genetic
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Affiliation(s)
- Madeleine Dahlbäck
- Centre for Medical Parasitology, University of Copenhagen and Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Thomas S Rask
- Center for Biological Sequence Analysis, BioCentrum, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Pernille H Andersen
- Center for Biological Sequence Analysis, BioCentrum, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Morten A Nielsen
- Centre for Medical Parasitology, University of Copenhagen and Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Nicaise T Ndam
- Centre for Medical Parasitology, University of Copenhagen and Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
- Institut de Recherche pour le Développement, Faculté de Pharmacie, Paris, France
| | - Mafalda Resende
- Centre for Medical Parasitology, University of Copenhagen and Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Louise Turner
- Centre for Medical Parasitology, University of Copenhagen and Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Philippe Deloron
- Institut de Recherche pour le Développement, Faculté de Pharmacie, Paris, France
| | - Lars Hviid
- Centre for Medical Parasitology, University of Copenhagen and Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Ole Lund
- Center for Biological Sequence Analysis, BioCentrum, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Anders Gorm Pedersen
- Center for Biological Sequence Analysis, BioCentrum, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Thor G Theander
- Centre for Medical Parasitology, University of Copenhagen and Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Ali Salanti
- Centre for Medical Parasitology, University of Copenhagen and Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
- * To whom correspondence should be addressed. E-mail:
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Joergensen L, Turner L, Magistrado P, Dahlbäck MA, Vestergaard LS, Lusingu JP, Lemnge M, Salanti A, Theander TG, Jensen ATR. Limited cross-reactivity among domains of the Plasmodium falciparum clone 3D7 erythrocyte membrane protein 1 family. Infect Immun 2006; 74:6778-84. [PMID: 17015460 PMCID: PMC1698063 DOI: 10.1128/iai.01187-06] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The var gene-encoded Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family is responsible for antigenic variation and sequestration of infected erythrocytes during malaria. We have previously grouped the 60 PfEMP1 variants of P. falciparum clone 3D7 into groups A and B/A (category A) and groups B, B/C, and C (category non-A). Expression of category A molecules is associated with severe malaria, and that of category non-A molecules is associated with uncomplicated malaria and asymptomatic infection. Here we assessed cross-reactivity among 60 different recombinant PfEMP1 domains derived from clone 3D7 by using a competition enzyme-linked immunosorbent assay and a pool of plasma from 63 malaria-exposed Tanzanian individuals. We conclude that naturally acquired antibodies are largely directed toward epitopes varying between different domains with a few, mainly category A, domains sharing cross-reactive antibody epitopes. Identification of groups of serological cross-reacting molecules is pivotal for the development of vaccines based on PfEMP1.
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Affiliation(s)
- Louise Joergensen
- University of Copenhagen, Department of Medical Microbiology and Immunology, Panum 24.2.24, Blegdamsvej 3, Copenhagen DK-2200, Denmark
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40
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Achtman AH, Bull PC, Stephens R, Langhorne J. Longevity of the Immune Response and Memory to Blood-Stage Malaria Infection. Curr Top Microbiol Immunol 2005; 297:71-102. [PMID: 16265903 DOI: 10.1007/3-540-29967-x_3] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Immunity to malaria develops slowly with protection against the parasite lagging behind protection against disease symptoms. The data on the longevity of protective immune responses are sparse. However, studies of antibody responses associated with protection reveal that they consist of a short- and a long-lived component. Compared with the antibody levels observed in other infection and immunization systems, the levels of the short-lived antibody compartment drop below the detectable threshold with unusual rapidity. The prevalence of long-lived antibodies is comparable to that seen after bacterial and protozoan infections. There is even less available data concerning T cell longevity in malaria infection, but what there is seems to indicate that T cell memory is short in the absence of persistent antigen. In general, the degree and duration of parasite persistence represent a major factor determining how immune response longevity and protection correlate. The predilection for short-lived immune responses in malaria infection could be caused by a number of mechanisms resulting from the interplay of normal regulatory mechanisms of the immune system and immune evasion by the parasite. In conclusion, it appears that the parasite-host relationship has developed to favor some short-lived responses, which allow the host to survive while allowing the parasite to persist. Anti-malarial immune responses present a complex picture, and many aspects of regulation and longevity of the response require further research.
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Affiliation(s)
- A H Achtman
- Molecular Tumor Genetics and Immunogenetics, Max-Delbrück-Center for Molecular Medicine, Berlin, Germany.
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Mutabingwa TK, Bolla MC, Li JL, Domingo GJ, Li X, Fried M, Duffy PE. Maternal malaria and gravidity interact to modify infant susceptibility to malaria. PLoS Med 2005; 2:e407. [PMID: 16259531 PMCID: PMC1277932 DOI: 10.1371/journal.pmed.0020407] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2005] [Accepted: 10/07/2005] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND In endemic areas, placental malaria due to Plasmodium falciparum is most frequent and severe in first-time mothers, and increases the risk of infant mortality in their offspring. Placental malaria may increase the susceptibility of infants to malaria parasitemia, but evidence for this effect is inconclusive. METHODS AND FINDINGS During 2002-2004, we monitored parasitemia in 453 infants, including 69 who were born to mothers with placental malaria, in a region of northeastern Tanzania where malaria transmission is intense. We used a Cox proportional hazards model to evaluate the time from birth to first parasitemia, and a generalized estimating equations logistic regression model to evaluate risk of any parasitemia throughout the first year of life. Compared with infants whose mothers did not have placental malaria at delivery ("PM-negative"), offspring of mothers with placental malaria at delivery ("PM-positive") were 41% more likely to experience their first parasitemia at a younger age (adjusted hazard ratio [AHR] = 1.41, 95% confidence interval [CI] 1.01-1.99). The odds of parasitemia throughout infancy were strongly modified by the interaction between placental malaria and gravidity (p for interaction = 0.008, Type 3 likelihood ratio test). Offspring of PM-negative primigravidae had lower odds of parasitemia during infancy (adjusted odds ratio [AOR] = 0.67, 95% CI 0.50-0.91) than offspring of PM-negative multigravidae, and offspring of PM-positive primigravidae had the lowest odds (AOR = 0.21, 95% CI 0.09-0.47). In contrast, offspring of PM-positive multigravidae had significantly higher odds of parasitemia (AOR = 1.59, 95% CI 1.16-2.17). CONCLUSION Although parasitemia is more frequent in primigravid than multigravid women, the converse is true in their offspring, especially in offspring of PM-positive women. While placental malaria is known to increase mortality risk for first-born infants, it surprisingly reduced their risk of parasitemia in this study. Placental malaria of multigravidae, on the other hand, is a strong risk factor for parasitemia during infancy, and therefore preventive antimalarial chemotherapy administered to multigravid women close to term may reduce the frequency of parasitemia in their offspring.
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Affiliation(s)
- Theonest K Mutabingwa
- 1MOMS Project, Malaria Antigen Discovery Program, Seattle Biomedical Research Institute, Seattle, Washington, United States of America
- 2Gates Malaria Partnership, London School of Hygiene and Tropical Medicine, London, United Kingdom
- 3National Institute for Medical Research, Muheza Designated District Hospital, Muheza-Tanga, Tanzania
| | - Melissa C Bolla
- 1MOMS Project, Malaria Antigen Discovery Program, Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - Jin-Long Li
- 1MOMS Project, Malaria Antigen Discovery Program, Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - Gonzalo J Domingo
- 1MOMS Project, Malaria Antigen Discovery Program, Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - Xiaohong Li
- 4Statistical Center for HIV/AIDS Research & Prevention, Department of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Michal Fried
- 1MOMS Project, Malaria Antigen Discovery Program, Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - Patrick E Duffy
- 1MOMS Project, Malaria Antigen Discovery Program, Seattle Biomedical Research Institute, Seattle, Washington, United States of America
- 5Department of Immunology, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
- *To whom correspondence should be addressed. E-mail:
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Abstract
It is widely perceived that immunity to malaria is, to an extent, defective and that one component of this defective immune response is the inability to induce or maintain long-term memory responses. If true, this is likely to pose problems for development of an effective vaccine against malaria. In this article, we critically review and challenge this interpretation of the epidemiological and experimental evidence. While evasion and modulation of host immune responses clearly occurs and naturally acquired immunity is far from optimal, mechanisms to control blood-stage parasites are acquired and maintained by individuals living in endemic areas, allowing parasite density to be kept below the threshold for induction of acute disease. Furthermore, protective immunity to severe pathology is achieved relatively rapidly and is maintained in the absence of boosting by re-infection. Nevertheless, there are significant challenges to overcome. The need for multiple infections to acquire immunity means that young children remain at risk of infection for far too long. Persistent or frequent exposure to antigen seems to be required to maintain anti-parasite immunity (premunition). Lastly, pre-erythrocytic and sexual stages of the life cycle are poorly immunogenic, and there is little evidence of effective pre-erythrocytic or transmission-blocking immunity at the population level. While these problems might theoretically be due to defective immunological memory, we suggest alternative explanations. Moreover, we question the extent to which these problems are malaria-specific rather than generic (i.e. result from inherent limitations of the vertebrate immune system).
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Affiliation(s)
- Siske S Struik
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
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43
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Jensen ATR, Magistrado P, Sharp S, Joergensen L, Lavstsen T, Chiucchiuini A, Salanti A, Vestergaard LS, Lusingu JP, Hermsen R, Sauerwein R, Christensen J, Nielsen MA, Hviid L, Sutherland C, Staalsoe T, Theander TG. Plasmodium falciparum associated with severe childhood malaria preferentially expresses PfEMP1 encoded by group A var genes. ACTA ACUST UNITED AC 2004; 199:1179-90. [PMID: 15123742 PMCID: PMC2211911 DOI: 10.1084/jem.20040274] [Citation(s) in RCA: 242] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Parasite-encoded variant surface antigens (VSAs) like the var gene-encoded Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family are responsible for antigenic variation and infected red blood cell (RBC) cytoadhesion in P. falciparum malaria. Parasites causing severe malaria in nonimmune patients tend to express a restricted subset of VSA (VSA(SM)) that differs from VSA associated with uncomplicated malaria and asymptomatic infection (VSA(UM)). We compared var gene transcription in unselected P. falciparum clone 3D7 expressing VSA(UM) to in vitro-selected sublines expressing VSA(SM) to identify PfEMP1 responsible for the VSA(SM) phenotype. Expression of VSA(SM) was accompanied by up-regulation of Group A var genes. The most prominently up-regulated Group A gene (PFD1235w/MAL7P1.1) was translated into a protein expressed on the infected RBC surface. The proteins encoded by Group A var genes, such as PFD1235w/MAL7P1.1, appear to be involved in the pathogenesis of severe disease and are thus attractive candidates for a vaccine against life-threatening P. falciparum malaria.
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Affiliation(s)
- Anja T R Jensen
- Department of Medical Microbiology and Immunology, The Panum Institute, Building 24-2, Blegdamsvej 3, 2200 Copenhagen, Denmark.
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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.
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Affiliation(s)
- Niloofar Rasti
- Microbiology and Tumour Biology Centre, Karolinska Institute, Swedish Institute for Infectious Disease Control, Box 280, 171 77 Stockholm, Sweden
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