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Hergott DEB, Owalla TJ, Staubus WJ, Seilie AM, Chavtur C, Balkus JE, Apio B, Lema J, Cemeri B, Akileng A, Chang M, Egwang TG, Murphy SC. Assessing the daily natural history of asymptomatic Plasmodium infections in adults and older children in Katakwi, Uganda: a longitudinal cohort study. THE LANCET. MICROBE 2024; 5:e72-e80. [PMID: 38185134 PMCID: PMC10790327 DOI: 10.1016/s2666-5247(23)00262-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 08/13/2023] [Accepted: 08/16/2023] [Indexed: 01/09/2024]
Abstract
BACKGROUND Low-density asymptomatic Plasmodium infections are prevalent in endemic areas, but little is known about their natural history. The trajectories of these infections and their propensity to fluctuate to undetectable densities can affect detection in clinical trials and field studies. We aimed to classify the natural history of these infections in a high transmission area over 29 days. METHODS In this longitudinal cohort study, we enrolled healthy, malaria-asymptomatic, afebrile, adults (age 18-59 years) and older children (age 8-17 years) in Katakwi District, Uganda, who were negative for Plasmodium infection on rapid diagnostic tests. Participants were instructed to self-collect one dried blood spot (DBS) per day for a maximum of 29 days. We excluded people if they were pregnant or taking antimalarials. During weekly clinic visits, staff collected a DBS and a 4 mL sample of venous blood. We analysed DBSs by Plasmodium 18S rRNA quantitative RT-PCR (qRT-PCR). We classified DBS by infection type as negative, P falciparum, non-P falciparum, or mixed. We plotted infection type over time for each participant and categorised trajectories as negative, new, cleared, chronic, or indeterminate infections. To estimate the effect of single timepoint sampling, we calculated the daily prevalence for each study day and estimated the number of infections that would have been detected in our population if sampling frequency was reduced. FINDINGS Between April 9 and May 20, 2021, 3577 DBSs were collected by 128 (40 male adults, 60 female adults, 12 male children, and 16 female children) study participants. 2287 (64%) DBSs were categorised as negative, 751 (21%) as positive for P falciparum, 507 (14%) as positive for non-P falciparum, and 32 (1%) as mixed infections. Daily Plasmodium prevalence in the population ranged from 45·3% (95% CI 36·6-54·1) at baseline to 30·3% (21·9-38·6) on day 24. 37 (95%) of 39 P falciparum and 35 (85%) of 41 non-P falciparum infections would have been detected with every other day sampling, whereas, with weekly sampling, 35 (90%) P falciparum infections and 31 (76%) non-P falciparum infections would have been detected. INTERPRETATION Parasite dynamics and species are highly variable among low-density asymptomatic Plasmodium infections. Sampling every other day or every 3 days detected a similar proportion of infections as daily sampling, whereas testing once per week or even less frequently could misclassify up to a third of the infections. Even using highly sensitive diagnostics, single timepoint testing might misclassify the true infection status of an individual. FUNDING US National Institutes of Health and Bill and Melinda Gates Foundation.
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Affiliation(s)
- Dianna E B Hergott
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA; Department of Epidemiology, School of Public Health, University of Washington, Seattle, WA, USA
| | - Tonny J Owalla
- Department of Parasitology and Immunology, Med Biotech Laboratories, Kampala, Uganda
| | - Weston J Staubus
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA; Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | - Annette M Seilie
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA; Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | - Chris Chavtur
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA; Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | - Jennifer E Balkus
- Department of Epidemiology, School of Public Health, University of Washington, Seattle, WA, USA
| | - Bernadette Apio
- Department of Parasitology and Immunology, Med Biotech Laboratories, Kampala, Uganda
| | - Jimmy Lema
- Department of Parasitology and Immunology, Med Biotech Laboratories, Kampala, Uganda
| | - Barbara Cemeri
- Department of Parasitology and Immunology, Med Biotech Laboratories, Kampala, Uganda
| | - Andrew Akileng
- Department of Parasitology and Immunology, Med Biotech Laboratories, Kampala, Uganda
| | - Ming Chang
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA; Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | - Thomas G Egwang
- Department of Parasitology and Immunology, Med Biotech Laboratories, Kampala, Uganda
| | - Sean C Murphy
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA; Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, USA; Department of Microbiology, University of Washington, Seattle, WA, USA.
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2
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Agonhossou R, Akoton R, Lagnika H, Djihinto OY, Sovegnon PM, Saizonou HD, Ntoumi F, Wondji CS, Borrmann S, Adegnika AA, Djogbénou LS. P. falciparum msp1 and msp2 genetic diversity in P. falciparum single and mixed infection with P. malariae among the asymptomatic population in Southern Benin. Parasitol Int 2022; 89:102590. [PMID: 35472441 DOI: 10.1016/j.parint.2022.102590] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 04/17/2022] [Accepted: 04/19/2022] [Indexed: 10/18/2022]
Abstract
Plasmodium falciparum and Plasmodium malariae infections are prevalent in malaria-endemic countries. However, very little is known about their interactions especially the effect of P. malariae on P. falciparum genetic diversity. This study aimed to assess P. falciparum genetic diversity in P. falciparum and mixed infection P. falciparum/P. malariae isolates among the asymptomatic populations in Southern Benin. Two hundred and fifty blood samples (125 of P. falciparum and 125 P. falciparum/P. malariae isolates) were analysed by a nested PCR amplification of msp1 and msp2 genes. The R033 allelic family was the most represented for the msp1 gene in mono and mixed infection isolates (99.2% vs 86.4%), while the K1 family had the lowest frequency (38.3% vs 20.4%). However, with the msp2 gene, the two allelic families displayed similar frequencies in P. falciparum isolates while the 3D7 allelic family was more represented in P. falciparum/P. malariae isolates (88.7%). Polyclonal infections were also lower (62.9%) in P. falciparum/P. malariae isolates (p < 0.05). Overall, 96 individual alleles were identified (47 for msp1 and 49 for msp2) in P. falciparum isolates while a total of 50 individual alleles were identified (23 for msp1 and 27 for msp2) in P. falciparum/P. malariae isolates. The Multiplicity of Infection (MOI) was lower in P. falciparum/P. malariae isolates (p < 0.05). This study revealed a lower genetic diversity of P. falciparum in P. falciparum/P. malariae isolates using msp1 and msp2 genes among the asymptomatic population in Southern Benin.
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Affiliation(s)
- Romuald Agonhossou
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin; Fondation Pour la Recherche Scientifique (FORS), ISBA, BP 88, Cotonou, Bénin.
| | - Romaric Akoton
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin; Fondation Pour la Recherche Scientifique (FORS), ISBA, BP 88, Cotonou, Bénin
| | - Hamirath Lagnika
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin
| | - Oswald Y Djihinto
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin
| | - Pierre M Sovegnon
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin
| | - Helga D Saizonou
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin
| | - Francine Ntoumi
- Fondation Congolaise pour la Recherche Médicale (FCRM), Brazzaville, Congo; Institute for Tropical Medicine (ITM), University of Tübingen, Tübingen, Germany
| | - Charles S Wondji
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; Department of Parasitology and Medical Entomology, Centre for Research in Infectious Diseases (CRID), Yaoundé, Centre Region, 237, Cameroon
| | - Steffen Borrmann
- Institute for Tropical Medicine (ITM), University of Tübingen, Tübingen, Germany; German Center for Infection Research (DZIF), Tübingen, Germany
| | - Ayola A Adegnika
- Fondation Pour la Recherche Scientifique (FORS), ISBA, BP 88, Cotonou, Bénin; Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon; Institute for Tropical Medicine (ITM), University of Tübingen, Tübingen, Germany; Eberhard Karls Universität Tübingen, Tübingen, Germany; German Center for Infection Research (DZIF), Tübingen, Germany
| | - Luc S Djogbénou
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin; Institut Régional de Santé Publique/Université d'Abomey-Calavi, BP 384 Ouidah, Bénin
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3
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Jafari-Guemouri S, Courtois L, Mama A, Rouas B, Neto Braga G, Accrombessi M, Massougbodji A, Ding XC, Tuikue Ndam N, Fievet N, Briand V. A Genotyping Study in Benin Comparing the Carriage of Plasmodium falciparum Infections Before Pregnancy and in Early Pregnancy: Story of a Persistent Infection. Clin Infect Dis 2021; 73:e355-e361. [PMID: 32569359 PMCID: PMC8282262 DOI: 10.1093/cid/ciaa841] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 06/17/2020] [Indexed: 12/16/2022] Open
Abstract
Background Malaria infections in the first trimester of pregnancy are frequent and deleterious for both mother and child health. To investigate if these early infections are newly acquired or already present in the host, we assessed whether parasites detected before pregnancy and those detected in early pregnancy are the same infection. Methods We used data from the preconceptional “RECIPAL” study (Benin, 2014–2017). Sixty-three pregnant women of 411 included who had a malaria infection detected by quantitative polymerase chain reaction both before pregnancy and at the first antenatal care (ANC) visit were selected for this study. Two highly polymorphic markers, msp-2 and glurp, and a fragment-analysis method were used to enumerate the Plasmodium falciparum genotypes and to quantify their proportions within isolates. An infection was considered as persistent when identical msp-2 and glurp genotypes were found in the corresponding prepregnancy and early-pregnancy samples. Results The median time between the 2 malaria screenings was 3 months. The median gestational age at the first ANC visit was 6.4 weeks. Most infections before pregnancy were submicroscopic infections. Based on both msp-2 and glurp genotyping, the infection was similar before and in early pregnancy in 46% (29/63) of cases. Conclusions Almost half of P. falciparum infections detected in the first trimester originate before pregnancy. Protecting young women from malaria infection before pregnancy might reduce the prevalence of malaria in early pregnancy and its related poor maternal and birth outcomes.
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Affiliation(s)
- Sayeh Jafari-Guemouri
- Université de Paris, UMR261-MERIT, Institut de Recherche pour le Développement, Paris, France
| | - Laura Courtois
- Université de Paris, UMR261-MERIT, Institut de Recherche pour le Développement, Paris, France
| | - Atika Mama
- Clinical Research Institute of Benin (IRCB), Abomey-Calavi, Benin
| | - Baptiste Rouas
- Université de Paris, UMR261-MERIT, Institut de Recherche pour le Développement, Paris, France
| | - Gabriel Neto Braga
- Université de Paris, UMR261-MERIT, Institut de Recherche pour le Développement, Paris, France
| | - Manfred Accrombessi
- Clinical Research Institute of Benin (IRCB), Abomey-Calavi, Benin.,Faculty of Infectious and Tropical Diseases, Disease Control Department, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | | | - Nicaise Tuikue Ndam
- Université de Paris, UMR261-MERIT, Institut de Recherche pour le Développement, Paris, France
| | - Nadine Fievet
- Université de Paris, UMR261-MERIT, Institut de Recherche pour le Développement, Paris, France
| | - Valérie Briand
- Université de Paris, UMR261-MERIT, Institut de Recherche pour le Développement, Paris, France.,University of Bordeaux, Inserm, Institut de Recherche pour le Développement, Inserm, University of Bordeaux, UMR, Bordeaux, France
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4
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Greischar MA, Reece SE, Savill NJ, Mideo N. The Challenge of Quantifying Synchrony in Malaria Parasites. Trends Parasitol 2019; 35:341-355. [PMID: 30952484 DOI: 10.1016/j.pt.2019.03.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 03/04/2019] [Accepted: 03/05/2019] [Indexed: 12/21/2022]
Abstract
Malaria infection is often accompanied by periodic fevers, triggered by synchronous cycles of parasite replication within the host. The degree of synchrony in parasite development influences the efficacy of drugs and immune defenses and is therefore relevant to host health and infectiousness. Synchrony is thought to vary over the course of infection and across different host-parasite genotype or species combinations, but the evolutionary significance - if any - of this diversity remains elusive. Standardized methods are lacking, but the most common metric for quantifying synchrony is the percentage of parasites in a particular developmental stage. We use a heuristic model to show that this metric is often unacceptably biased. Methodological challenges must be addressed to characterize diverse patterns of synchrony and their consequences for disease severity and spread.
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Affiliation(s)
- Megan A Greischar
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada.
| | - Sarah E Reece
- Institute of Evolutionary Biology and Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, UK
| | - Nicholas J Savill
- Institute of Evolutionary Biology and Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, UK
| | - Nicole Mideo
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
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5
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Slater HC, Ross A, Felger I, Hofmann NE, Robinson L, Cook J, Gonçalves BP, Björkman A, Ouedraogo AL, Morris U, Msellem M, Koepfli C, Mueller I, Tadesse F, Gadisa E, Das S, Domingo G, Kapulu M, Midega J, Owusu-Agyei S, Nabet C, Piarroux R, Doumbo O, Doumbo SN, Koram K, Lucchi N, Udhayakumar V, Mosha J, Tiono A, Chandramohan D, Gosling R, Mwingira F, Sauerwein R, Paul R, Riley EM, White NJ, Nosten F, Imwong M, Bousema T, Drakeley C, Okell LC. The temporal dynamics and infectiousness of subpatent Plasmodium falciparum infections in relation to parasite density. Nat Commun 2019; 10:1433. [PMID: 30926893 PMCID: PMC6440965 DOI: 10.1038/s41467-019-09441-1] [Citation(s) in RCA: 96] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 03/07/2019] [Indexed: 02/08/2023] Open
Abstract
Malaria infections occurring below the limit of detection of standard diagnostics are common in all endemic settings. However, key questions remain surrounding their contribution to sustaining transmission and whether they need to be detected and targeted to achieve malaria elimination. In this study we analyse a range of malaria datasets to quantify the density, detectability, course of infection and infectiousness of subpatent infections. Asymptomatically infected individuals have lower parasite densities on average in low transmission settings compared to individuals in higher transmission settings. In cohort studies, subpatent infections are found to be predictive of future periods of patent infection and in membrane feeding studies, individuals infected with subpatent asexual parasite densities are found to be approximately a third as infectious to mosquitoes as individuals with patent (asexual parasite) infection. These results indicate that subpatent infections contribute to the infectious reservoir, may be long lasting, and require more sensitive diagnostics to detect them in lower transmission settings. The role of subpatent infections for malaria transmission and elimination is unclear. Here, Slater et al. analyse several malaria datasets to quantify the density, detectability, course of infection and infectiousness of subpatent infections.
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Affiliation(s)
- Hannah C Slater
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, W2 1PG, UK.
| | - Amanda Ross
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, 4002, Switzerland.,University of Basel, Basel, 4001, Switzerland
| | - Ingrid Felger
- University of Basel, Basel, 4001, Switzerland.,Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, 4002, Switzerland
| | - Natalie E Hofmann
- University of Basel, Basel, 4001, Switzerland.,Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, 4002, Switzerland
| | - Leanne Robinson
- Vector-borne Diseases Unit, Papua New Guinea Institute for Medical Research, Madang, Papua New Guinea.,Division of Population Health and Immunity, The Walter and Eliza Hall Institute of Medical Research, Parkville, 3052, VIC, Australia.,Medical Biology, University of Melbourne, Melbourne, 3010, VIC, Australia.,Disease Elimination, Burnet Institute, Melbourne, 3004, VIC, Australia
| | - Jackie Cook
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Bronner P Gonçalves
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Anders Björkman
- Malaria Research, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Andre Lin Ouedraogo
- Département de Sciences Biomédicales, Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, 01 BP 2208, Burkina Faso.,Institute for Disease Modeling, Intellectual Ventures, Bellevue, 98005, Washington, USA
| | - Ulrika Morris
- Malaria Research, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Mwinyi Msellem
- Department of Training and Research, Mnazi Mmoja Hospital, Zanzibar, Tanzania
| | - Cristian Koepfli
- Population Health and Immunity Division, Walter and Eliza Hall Institute, Melbourne, 3052, Victoria, Australia.,Department of Biological Sciences, University of Notre Dame, Indiana, 46556, USA
| | - Ivo Mueller
- Division of Population Health and Immunity, The Walter and Eliza Hall Institute of Medical Research, Parkville, 3052, VIC, Australia.,Department of Parasites and Insect Vectors, Institut Pasteur, Paris, 75015, France.,Medical Biology, University of Melbourne, Melbourne, 3010, VIC, Australia
| | - Fitsum Tadesse
- Radboud Institute for Health Sciences, Radboud University Medical Centre, Nijmegen, 6525, The Netherlands.,Armauer Hansen Research Institute, Addis Ababa, Ethiopia.,Institute of Biotechnology, Addis Ababa University, Addis Ababa, Ethiopia
| | | | - Smita Das
- Diagnostics Program, PATH, Seattle, Washington, 98121, United States of America
| | - Gonzalo Domingo
- Diagnostics Program, PATH, Seattle, Washington, 98121, United States of America
| | - Melissa Kapulu
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK.,KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya, Centre for Genomics and Global Health, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Janet Midega
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK.,KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya, Centre for Genomics and Global Health, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Seth Owusu-Agyei
- Institute of Health, University of Health and Allied Sciences, Hohoe, PMB 31, Ghana
| | - Cécile Nabet
- Sorbonne Université, INSERM, Institut Pierre-Louis d'Epidémiologie et de Santé Publique, AP- HP, Groupe Hospitalier Pitié-Salpêtrière, Service de Parasitologie-Mycologie, Paris, 75646, France
| | - Renaud Piarroux
- Sorbonne Université, INSERM, Institut Pierre-Louis d'Epidémiologie et de Santé Publique, AP- HP, Groupe Hospitalier Pitié-Salpêtrière, Service de Parasitologie-Mycologie, Paris, 75646, France
| | - Ogobara Doumbo
- Malaria Research and Training Centre, Parasitic Diseases Epidemiology Department, UMI 3189, University of Sciences, Technique and Technology, Bamako, Mali
| | - Safiatou Niare Doumbo
- Malaria Research and Training Centre, Parasitic Diseases Epidemiology Department, UMI 3189, University of Sciences, Technique and Technology, Bamako, Mali
| | - Kwadwo Koram
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Naomi Lucchi
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Global Health, Centers for Disease Control and Prevention, Atlanta, 30030, GA, United States of America
| | - Venkatachalam Udhayakumar
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Global Health, Centers for Disease Control and Prevention, Atlanta, 30030, GA, United States of America
| | - Jacklin Mosha
- National Institute for Medical Research, Mwanza Medical Research Centre, Mwanza, Tanzania
| | - Alfred Tiono
- Department of Biomedical Sciences, Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, 01 BP 2208, Burkina Faso
| | - Daniel Chandramohan
- Department of Disease Control, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Roly Gosling
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, San Francisco, 94158, CA, United States
| | - Felista Mwingira
- Biological Sciences Department, Dar es Salaam University College of Education, P. O. Box 2329, Dar es Salaam, Tanzania
| | - Robert Sauerwein
- Radboud Institute for Health Sciences, Radboud University Medical Centre, Nijmegen, 6525, The Netherlands
| | - Richard Paul
- Institut Pasteur de Dakar, Laboratoire d'Entomologie Médicale, Dakar, Senegal
| | - Eleanor M Riley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK.,The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - Nicholas J White
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7FZ, UK.,Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
| | - Francois Nosten
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7FZ, UK.,Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, 63110, Thailand
| | - Mallika Imwong
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand.,Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
| | - Teun Bousema
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK.,Radboud Institute for Health Sciences, Radboud University Medical Centre, Nijmegen, 6525, The Netherlands
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Lucy C Okell
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, W2 1PG, UK
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6
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Genetic Polymorphism of msp1 and msp2 in Plasmodium falciparum Isolates from Côte d'Ivoire versus Gabon. J Parasitol Res 2016; 2016:3074803. [PMID: 27110390 PMCID: PMC4823507 DOI: 10.1155/2016/3074803] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 03/01/2016] [Accepted: 03/07/2016] [Indexed: 11/30/2022] Open
Abstract
Introduction. The characterization of genetic profile of Plasmodium isolates from different areas could help in better strategies for malaria elimination. This study aimed to compare P. falciparum diversity in two African countries. Methods. Isolates collected from 100 and 73 falciparum malaria infections in sites of Côte d'Ivoire (West Africa) and Gabon (Central Africa), respectively, were analyzed by a nested PCR amplification of msp1 and msp2 genes. Results. The K1 allelic family was widespread in Côte d'Ivoire (64.6%) and in Gabon (56.6%). For msp2, the 3D7 alleles were more prevalent (>70% in both countries) compared to FC27 alleles. In Côte d'Ivoire, the frequencies of multiple infections with msp1 (45.1%) and msp2 (40.3%) were higher than those found for isolates from Gabon, that is, 30.2% with msp1 and 31.4% with msp2. The overall complexity of infection was 1.66 (SD = 0.79) in Côte d'Ivoire and 1.58 (SD = 0.83) in Gabon. It decreased with age in Côte d'Ivoire in contrast to Gabon. Conclusion. Differences observed in some allelic families and in complexity profile may suggest an impact of epidemiological facies as well as immunological response on genetic variability of P. falciparum.
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7
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Abstract
Mathematical modelling provides an effective way to challenge conventional wisdom about
parasite evolution and investigate why parasites ‘do what they do’ within the host. Models
can reveal when intuition cannot explain observed patterns, when more complicated biology
must be considered, and when experimental and statistical methods are likely to mislead.
We describe how models of within-host infection dynamics can refine experimental design,
and focus on the case study of malaria to highlight how integration between models and
data can guide understanding of parasite fitness in three areas: (1) the adaptive
significance of chronic infections; (2) the potential for tradeoffs between virulence and
transmission; and (3) the implications of within-vector dynamics. We emphasize that models
are often useful when they highlight unexpected patterns in parasite evolution, revealing
instead why intuition yields the wrong answer and what combination of theory and data are
needed to advance understanding.
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8
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Mawili-Mboumba DP, Mbondoukwe N, Adande E, Bouyou-Akotet MK. Allelic Diversity of MSP1 Gene in Plasmodium falciparum from Rural and Urban Areas of Gabon. THE KOREAN JOURNAL OF PARASITOLOGY 2015; 53:413-9. [PMID: 26323839 PMCID: PMC4566513 DOI: 10.3347/kjp.2015.53.4.413] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 02/23/2015] [Accepted: 08/05/2015] [Indexed: 11/23/2022]
Abstract
The present study determined and compared the genetic diversity of Plasmodium falciparum strains infecting children living in 2 areas from Gabon with different malaria endemicity. Blood samples were collected from febrile children from 2008 to 2009 in 2 health centres from rural (Oyem) and urban (Owendo) areas. Genetic diversity was determined in P. falciparum isolates by analyzing the merozoite surface protein-1 (msp1) gene polymorphism using nested-PCR. Overall, 168 children with mild falciparum malaria were included. K1, Ro33, and Mad20 alleles were found in 110 (65.5%), 94 (55.9%), and 35 (20.8%) isolates, respectively, without difference according to the site (P>0.05). Allelic families' frequencies were comparable between children less than 5 years old from the 2 sites; while among the older children the proportions of Ro33 and Mad20 alleles were 1.7 to 2.0 fold higher at Oyem. Thirty-three different alleles were detected, 16 (48.5%) were common to both sites, and 10 out of the 17 specific alleles were found at Oyem. Furthermore, multiple infection carriers were frequent at Oyem (57.7% vs 42.2% at Owendo; P=0.04) where the complexity of infection was of 1.88 (±0.95) higher compared to that found at Owendo (1.55±0.75). Extended genetic diversity of P. falciparum strains infecting Gabonese symptomatic children and high multiplicity of infections were observed in rural area. Alleles common to the 2 sites were frequent; the site-specific alleles predominated in the rural area. Such distribution of the alleles should be taken into accounts when designing MSP1 or MSP2 malaria vaccine.
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Affiliation(s)
- Denise Patricia Mawili-Mboumba
- Department of Parasitology-Mycology, Faculty of Medicine, Université des Sciences de la Santé. BP4009, Libreville, Gabon
| | - Noé Mbondoukwe
- Department of Parasitology-Mycology, Faculty of Medicine, Université des Sciences de la Santé. BP4009, Libreville, Gabon
| | - Elvire Adande
- Department of Parasitology-Mycology, Faculty of Medicine, Université des Sciences de la Santé. BP4009, Libreville, Gabon
| | - Marielle Karine Bouyou-Akotet
- Department of Parasitology-Mycology, Faculty of Medicine, Université des Sciences de la Santé. BP4009, Libreville, Gabon
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Dynamics of clonal diversity in natural infections of the malaria parasite Plasmodium mexicanum in its free-ranging lizard host. Parasitol Res 2014; 113:2059-67. [PMID: 24647987 DOI: 10.1007/s00436-014-3854-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Accepted: 03/05/2014] [Indexed: 10/25/2022]
Abstract
Within mixed-genotype infections of malaria parasites (Plasmodium), the number of genetic clones present is associated with variation in important life history traits of the infection, including virulence. Although the number of clones present is important, how the proportion of those clones varies over time is poorly known. Clonal proportions of the lizard malaria parasite, Plasmodium mexicanum, were assessed in naturally infected free-ranging lizards followed in a mark-recapture program over as long as two warm seasons, the typical life span of the lizard. Clonal proportions were determined by amplifying two microsatellite markers, a method previously verified for accuracy. Most blood samples had been stored for over a decade, so a verification test determined that these samples had not degraded. Although the environment experienced by the parasite (its host) varies over the seasons and transmission occurs over the entire warm season, 68% of infections were stable over time, harboring a single clone (37% of infections) or multiple clones changing only 1-12% maximum comparing any two samples (31% of infections). The maximum change seen in any infection (comparing any two sample periods) was only 30%. A new clone entered three infections (only once successfully), and a clone was lost in only three infections. These results mirror those seen for a previous study of experimentally induced infections that showed little change in relative proportions over time. The results of this study, the first look at how clonal proportions vary over time for any malaria parasite of a nonhuman vertebrate host for natural infections, were surprising because experimental studies show clones of P. mexicanum appear to interact, yet relative proportions of clones typically remain constant over time.
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Ogouyèmi-Hounto A, Gazard DK, Ndam N, Topanou E, Garba O, Elegbe P, Hountohotegbe T, Massougbodji A. Genetic polymorphism of merozoite surface protein-1 and merozoite surface protein-2 in Plasmodium falciparum isolates from children in South of Benin. ACTA ACUST UNITED AC 2013; 20:37. [PMID: 24135216 PMCID: PMC3798888 DOI: 10.1051/parasite/2013039] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 10/06/2013] [Indexed: 01/22/2023]
Abstract
The aim of this study was to determine the genetic diversity of Plasmodium falciparum by analyzing the polymorphism of the msp-1 and msp-2 genes and the multiplicity of infection in children with uncomplicated malaria in southern Benin. Blood samples of children with fever or history of fever with thick smear positive P. falciparum were collected on filter paper. After extraction of DNA by Chelex®, the samples underwent nested PCR. 93 isolates from children were genotyped. For the msp-1 gene, the K1 and R033 sequences were the most represented in the study population with 85.2% and 83% prevalence, respectively. Regarding the msp-2 gene, the FC27 family was more highly represented with 99% prevalence against 81.5% for 3D7. Mixed infections accounted for 80.4% of the samples. Twenty-five alleles were identified for msp-1 and 28 for msp-2. Fourteen and ten alleles belonged to the K1 (100-500 bp) and MAD20 (100-500 bp) families, respectively. The RO33 sequence did not show any polymorphism, with only one variant (160 bp) detected. The msp-2 gene was present as 16 FC27 family fragments (250-800 bp) and 12 of the 3D7 family (350-700 bp). The multiplicity of infection was estimated at 3.8 for msp-1 and 3.9 for msp-2 with 77 (87.5%) and 84 (91.3%) samples harboring more than one parasite genotype for msp-1 and msp-2, respectively. The multiplicity of infection (MOI) was influenced neither by age nor by parasite density. This study shows a significant diversity of P. falciparum in southern Benin with an MOI unaffected by age or by parasite density.
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Affiliation(s)
- Aurore Ogouyèmi-Hounto
- Unité d'Enseignement et de Recherche en Parasitologie-Mycologie de la Faculté des Sciences de la Santé, 01BP188 Cotonou, Bénin - Laboratoire du Centre de Lutte Intégrée contre le Paludisme, 01BP188 Cotonou, Bénin
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Babiker HA, Gadalla AAH, Ranford-Cartwright LC. The role of asymptomatic P. falciparum parasitaemia in the evolution of antimalarial drug resistance in areas of seasonal transmission. Drug Resist Updat 2013; 16:1-9. [PMID: 23510592 DOI: 10.1016/j.drup.2013.02.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 02/11/2013] [Indexed: 01/15/2023]
Abstract
In areas with seasonal transmission, proper management of acute malaria cases that arise in the transmission season can markedly reduce the disease burden. However, asymptomatic carriage of Plasmodium falciparum sustains a long-lasting reservoir in the transmission-free dry season that seeds cyclical malaria outbreaks. Clinical trials targeting asymptomatic parasitaemia in the dry season failed to interrupt the malaria epidemics that follow annual rains. These asymptomatic infections tend to carry multiple-clones, capable of producing gametocytes and infecting Anopheles mosquitoes. Different clones within an infection fluctuate consistently, indicative of interaction between clones during the long course of asymptomatic carriage. However, the therapy-free environment that prevails in the dry season dis-advantages the drug resistant lineages and favors the wild-type parasites. This review highlights some biological and epidemiological characteristics of asymptomatic parasitaemia and calls for consideration of policies to diminish parasite exposure to drugs "therapy-free" and allow natural selection to curb drug resistance in the above setting.
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Affiliation(s)
- Hamza A Babiker
- Biochemistry Department, Faculty of Medicine, Sultan Qaboos University, Oman.
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12
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Koukouikila-Koussounda F, Malonga V, Mayengue PI, Ndounga M, Vouvoungui CJ, Ntoumi F. Genetic polymorphism of merozoite surface protein 2 and prevalence of K76T pfcrt mutation in Plasmodium falciparum field isolates from Congolese children with asymptomatic infections. Malar J 2012; 11:105. [PMID: 22463364 PMCID: PMC3349535 DOI: 10.1186/1475-2875-11-105] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 04/01/2012] [Indexed: 12/15/2022] Open
Abstract
Background In order to prepare the field site for future interventions, the prevalence of asymptomatic Plasmodium falciparum infection was evaluated in a cohort of children living in Brazzaville. Plasmodium falciparum merozoite surface protein 2 gene (msp2) was used to characterize the genetic diversity and the multiplicity of infection. The prevalence of mutant P. falciparum chloroquine resistance transporter (pfcrt) allele in isolates was also determined. Methods Between April and June 2010, 313 children below 10 years of age enrolled in the cohort for malaria surveillance were screened for P. falciparum infection using microscopy and polymerase chain reaction (PCR). The children were selected on the basis of being asymptomatic. Plasmodium falciparum msp2 gene was genotyped by allele-specific nested PCR and the pfcrt K76T mutation was detected using nested PCR followed by restriction endonuclease digestion. Results The prevalence of asymptomatic P. falciparum infections was 8.6% and 16% by microscopy and by PCR respectively. Allele typing of the msp2 gene detected 55% and 45% of 3D7 and FC27 allelic families respectively. The overall multiplicity of infections (MOI) was 1.3. A positive correlation between parasite density and multiplicity of infection was found. The prevalence of the mutant pfcrt allele (T76) in the isolates was 92%. Conclusion This is the first molecular characterization of P. falciparum field isolates in Congolese children, four years after changing the malaria treatment policy from chloroquine (CQ) to artemisinin-based combination therapy (ACT). The low prevalence of asymptomatic infections and MOI is discussed in the light of similar studies conducted in Central Africa.
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Carlsson AM, Ngasala BE, Dahlström S, Membi C, Veiga IM, Rombo L, Abdulla S, Premji Z, Gil JP, Björkman A, Mårtensson A. Plasmodium falciparum population dynamics during the early phase of anti-malarial drug treatment in Tanzanian children with acute uncomplicated malaria. Malar J 2011; 10:380. [PMID: 22185672 PMCID: PMC3280947 DOI: 10.1186/1475-2875-10-380] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Revised: 08/04/2011] [Accepted: 12/20/2011] [Indexed: 11/23/2022] Open
Abstract
Background This study aimed to explore Plasmodium falciparum population dynamics during the early phase of anti-malarial drug treatment with artemisinin-based combination therapy in children with clinical malaria in a high transmission area in Africa. Methods A total of 50 children aged 1-10 years with acute uncomplicated P. falciparum malaria in Bagamoyo District, Tanzania, were enrolled. Participants were hospitalized and received supervised standard treatment with artemether-lumefantrine according to body weight in six doses over 3 days. Blood samples were collected 11 times, i.e. at time of diagnosis (-2 h) and 0, 2, 4, 8, 16, 24, 36, 48, 60 and 72 h after initiation of treatment. Parasite population dynamics were assessed using nested polymerase chain reaction (PCR)-genotyping of merozoite surface protein (msp) 1 and 2. Results PCR-analyses from nine sequential blood samples collected after initiation of treatment identified 20 and 21 additional genotypes in 15/50 (30%) and 14/50 (28%) children with msp1 and msp2, respectively, non-detectable in the pre-treatment samples (-2 and 0 h combined). Some 15/20 (75%) and 14/21 (67%) of these genotypes were identified within 24 h, whereas 17/20 (85%) and 19/21 (90%) within 48 h for msp1 and msp2, respectively. The genotype profile was diverse, and varied considerably over time both within and between patients, molecular markers and their respective families. Conclusion PCR analyses from multiple blood samples collected during the early treatment phase revealed a complex picture of parasite sub-populations. This underlines the importance of interpreting PCR-outcomes with caution and suggests that the present use of PCR-adjustment from paired blood samples in anti-malarial drug trials may overestimate assessment of drug efficacy in high transmission areas in Africa. The study is registered at http://www.clinicaltrials.gov with identifier NCT00336375.
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Affiliation(s)
- Anja M Carlsson
- Infectious Diseases Unit, Department of Medicine Solna, Karolinska University Hospital, Karolinska Institutet, Retzius väg 10, S-171 77 Stockholm, Sweden
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Population pharmacokinetics and pharmacodynamics of artemether and lumefantrine during combination treatment in children with uncomplicated falciparum malaria in Tanzania. Antimicrob Agents Chemother 2010; 54:4780-8. [PMID: 20713675 DOI: 10.1128/aac.00252-10] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The combination of artemether (ARM) and lumefantrine is currently the first-line treatment of uncomplicated falciparum malaria in mainland Tanzania. While the exposure to lumefantrine has been associated with the probability of adequate clinical and parasitological cure, increasing exposure to artemether and the active metabolite dihydroartemisinin (DHA) has been shown to decrease the parasite clearance time. The aim of this analysis was to describe the pharmacokinetics and pharmacodynamics of artemether, dihydroartemisinin, and lumefantrine in African children with uncomplicated malaria. In addition to drug concentrations and parasitemias from 50 Tanzanian children with falciparum malaria, peripheral parasite densities from 11 asymptomatic children were included in the model of the parasite dynamics. The population pharmacokinetics and pharmacodynamics of artemether, dihydroartemisinin, and lumefantrine were modeled in NONMEM. The distribution of artemether was described by a two-compartment model with a rapid absorption and elimination through metabolism to dihydroartemisinin. Dihydroartemisinin concentrations were adequately illustrated by a one-compartment model. The pharmacokinetics of artemether was time dependent, with typical oral clearance increasing from 2.6 liters/h/kg on day 1 to 10 liters/h/kg on day 3. The pharmacokinetics of lumefantrine was sufficiently described by a one-compartment model with an absorption lag time. The typical value of oral clearance was estimated to 77 ml/h/kg. The proposed semimechanistic model of parasite dynamics, while a rough approximation of the complex interplay between malaria parasite and the human host, adequately described the early effect of ARM and DHA concentrations on the parasite density in malaria patients. However, the poor precision in some parameters illustrates the need for further data to support and refine this model.
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Juliano JJ, Gadalla N, Sutherland CJ, Meshnick SR. The perils of PCR: can we accurately 'correct' antimalarial trials? Trends Parasitol 2010; 26:119-24. [PMID: 20083436 DOI: 10.1016/j.pt.2009.12.007] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2009] [Revised: 11/17/2009] [Accepted: 12/22/2009] [Indexed: 01/17/2023]
Abstract
During follow-up in antimalarial drug trials, treated subjects can be newly infected. PCR correction is used to distinguish this re-infection from drug failure (recrudescence) and to adjust final drug efficacy estimates. The epidemiological, biological and technical limitations of PCR correction and how this can lead to misclassification in drug trial outcomes are underappreciated. This article considers these limitations and proposes a framework for reporting, interpreting and improving PCR correction of antimalarial trials.
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Affiliation(s)
- Jonathan J Juliano
- Division of Infectious Diseases, Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
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Touré-Ndouo FS, Zang-Edou ES, Bisvigou U, Mezui-Me-Ndong J. Relationship between in vivo synchronicity of Plasmodium falciparum and allelic diversity. Parasitol Int 2009; 58:390-3. [PMID: 19660576 DOI: 10.1016/j.parint.2009.07.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Revised: 07/24/2009] [Accepted: 07/27/2009] [Indexed: 10/20/2022]
Abstract
Plasmodium falciparum cells tend to grow in synchronicity during their cyclic intraerythrocytic development in vivo. Both host and parasite factors appear to be involved in this synchronization. We examined the link between mixed-allelic-family P. falciparum infection and synchronicity in parasitized red blood cells (PRBC) from symptomatic children. The distribution of rings and trophozoites in each PRBC sample was determined by standard microscopy. P. falciparum was genotyped by using a polymerase chain reaction (PCR) targeting three loci (merozoite surface proteins (MSP) 1 and 2, and 175-kD erythrocyte binding antigen (EBA), allowing us to distinguish parasite clones belonging to a single-allelic family (SAF) and those belonging to a mixed-allelic family (MAF). Parasite development was considered synchronous when peripheral blood contained at least 95% of rings or 95% of trophozoites. Parasite development was synchronous in 22 (21.2%) of the 104 children studied. Twenty (90.9%) of these infections were SAF and two (9.1%) were MAF. Rings and trophozoites predominated in respectively 12 (60%) and 8 (40%) SAF infections. Respectively 17.1% and 82.9% of the 82 asynchronous cases corresponded to SAF and MAF infection. Parasite synchronicity was therefore significantly related to single-allelic-family infection (p<2x10(-10)). Twenty different MSP-1 alleles and thirteen different MSP-2 alleles were identified. Only three isolates from patients with SAF infection comprised a single allele or genotype, the other isolates harboring at least two alleles. The mean number of alleles or clones was respectively 3.0 and 10.0 in SAF and MAF infection. These results reflect the allelic diversity of the MSP loci and show that SAF infection can correspond to multiple parasite clones (or genotypes) but, in general, fewer than in MAF infection (p<or=0.0007). These results confirm the extensive polymorphism of P. falciparum vaccine candidates MSP-1 and -2 in southeastern Gabon and demonstrate that parasite synchronicity in vivo is strongly associated with single-allelic-family infection.
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Liljander A, Wiklund L, Falk N, Kweku M, Mårtensson A, Felger I, Färnert A. Optimization and validation of multi-coloured capillary electrophoresis for genotyping of Plasmodium falciparum merozoite surface proteins (msp1 and 2). Malar J 2009; 8:78. [PMID: 19386138 PMCID: PMC2680902 DOI: 10.1186/1475-2875-8-78] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Accepted: 04/23/2009] [Indexed: 11/11/2022] Open
Abstract
Background Genotyping of Plasmodium falciparum based on PCR amplification of the polymorphic genes encoding the merozoite surface proteins 1 and 2 (msp1 and msp2) is well established in the field of malaria research to determine the number and types of concurrent clones in an infection. Genotyping is regarded essential in anti-malarial drug trials to define treatment outcome, by distinguishing recrudescent parasites from new infections. Because of the limitations in specificity and resolution of gel electrophoresis used for fragment analysis in most genotyping assays it became necessary to improve the methodology. An alternative technique for fragment analysis is capillary electrophoresis (CE) performed using automated DNA sequencers. Here, one of the most widely-used protocols for genotyping of P. falciparum msp1 and msp2 has been adapted to the CE technique. The protocol and optimization process as well as the potentials and limitations of the technique in molecular epidemiology studies and anti-malarial drug trials are reported. Methods The original genotyping assay was adapted by fluorescent labeling of the msp1 and msp2 allelic type specific primers in the nested PCR and analysis of the final PCR products in a DNA sequencer. A substantial optimization of the fluorescent assay was performed. The CE method was validated using known mixtures of laboratory lines and field samples from Ghana and Tanzania, and compared to the original PCR assay with gel electrophoresis. Results The CE-based method showed high precision and reproducibility in determining fragment size (< 1 bp). More genotypes were detected in mixtures of laboratory lines and blood samples from malaria infected children, compared to gel electrophoresis. The capacity to distinguish recrudescent parasites from new infections in an anti-malarial drug trial was similar by both methods, resulting in the same outcome classification, however with more precise determination by CE. Conclusion The improved resolution and reproducibility of CE in fragment sizing allows for comparison of alleles between separate runs and determination of allele frequencies in a population. The more detailed characterization of individual msp1 and msp2 genotypes may contribute to improved assessments in anti-malarial drug trials and to a further understanding of the molecular epidemiology of these polymorphic P. falciparum antigens.
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Affiliation(s)
- Anne Liljander
- Department of Medicine Solna, Karolinska Institutet, SE-171 76 Stockholm, Sweden.
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Nsobya SL, Kiggundu M, Joloba M, Dorsey G, Rosenthal PJ. Complexity of Plasmodium falciparum clinical samples from Uganda during short-term culture. J Infect Dis 2009; 198:1554-7. [PMID: 18808336 DOI: 10.1086/592506] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
We cultured Plasmodium falciparum parasites from 98 Ugandan children with malaria and determined the complexity of infection (COI) on the basis of msp-2 polymorphisms daily for 9 days. The mean COI decreased during culture from 1.73 to 1.56. New strains appeared after day 0 in 20 cultures. Strains disappeared after day 0 in 56% of 45 cultures that were initially mixed; persisting strains more commonly had wild-type dhfr (C59) and dhps (K540) sequences and mutant pfmdr1 (86Y) sequences. Thus, initial genotypes offer an imperfect representation of clinical COI. Loss of strains in culture may be due to diminished fitness of some drug-resistant strains.
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Affiliation(s)
- Samuel L Nsobya
- Department of Medicine, Makerere University, Kampala, Uganda
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Färnert A, Lebbad M, Faraja L, Rooth I. Extensive dynamics of Plasmodium falciparum densities, stages and genotyping profiles. Malar J 2008; 7:241. [PMID: 19025582 PMCID: PMC2605469 DOI: 10.1186/1475-2875-7-241] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2008] [Accepted: 11/21/2008] [Indexed: 02/17/2024] Open
Abstract
Background Individuals living in areas of high malaria transmission often have different Plasmodium falciparum clones detected in the peripheral blood over time. The aim of this study was to assess the dynamics of asymptomatic P. falciparum infections in a few hours intervals. Methods Capillary blood samples were collected 6-hourly during five days from asymptomatic children in a highly endemic area in Tanzania. Parasite densities and maturation stages were investigated by light microscopy. Types and number of clones were analysed by PCR based genotyping of the polymorphic merozoite surface proteins 1 and 2 genes. Results: Parasite densities and maturation stages fluctuated 48-hourly with a gradual shift into more mature forms. Various genotyping patterns were observed in repeated samples over five days with only few samples with identical profiles. Up to six alleles differed in samples collected six hours apart in the same individual. Conclusion This detailed assessment highlights the extensive within-host dynamics of P. falciparum populations and the limitations of single blood samples to determine parasite densities, stages and genotyping profiles in a malaria infected individual.
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Affiliation(s)
- Anna Färnert
- Unit of Infectious Diseases, Department of Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
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20
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Plasmodium falciparum population dynamics: only snapshots in time? Trends Parasitol 2008; 24:340-4. [PMID: 18617441 DOI: 10.1016/j.pt.2008.04.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Revised: 04/09/2008] [Accepted: 04/24/2008] [Indexed: 11/22/2022]
Abstract
Infections caused by the malaria parasite Plasmodium falciparum often comprise multiple genetically distinct clones. Individuals in endemic areas can have different clones detected in their peripheral blood over a few days or even hours. This reveals interesting within-host dynamics of multiclonal infections, which seem to differ in asymptomatic and symptomatic infections. As well as being an intriguing biological phenomenon that merits further understanding, the extensive dynamics of P. falciparum infections have practical implications on the design and interpretation of malaria studies. Most assessments will, indeed, only provide snapshots of the parasite population dynamics.
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Tuikue Ndam N, Bischoff E, Proux C, Lavstsen T, Salanti A, Guitard J, Nielsen MA, Coppée JY, Gaye A, Theander T, David PH, Deloron P. Plasmodium falciparum transcriptome analysis reveals pregnancy malaria associated gene expression. PLoS One 2008; 3:e1855. [PMID: 18365010 PMCID: PMC2267001 DOI: 10.1371/journal.pone.0001855] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Accepted: 02/20/2008] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Pregnancy-associated malaria (PAM) causing maternal anemia and low birth weight is among the multiple manifestations of Plasmodium falciparum malaria. Infected erythrocytes (iEs) can acquire various adhesive properties that mediate the clinical severity of malaria. Recent advances on the molecular basis of virulence and immune evasion have helped identify var2csa as a PAM-specific var gene. METHODOLOGY/PRINCIPAL FINDINGS The present study presents a genome-wide microarray transcript analysis of 18 P. falciparum parasite isolates freshly collected from the placenta. The proportion of PAM over-expressed genes located in subtelomeric regions as well as that of PAM over-expressed genes predicted to be exported were higher than expected compared to the whole genome. The identification of novel parasite molecules with specificity to PAM and which are likely involved in host-pathogen interactions and placental tropism is described. One of these proteins, PFI1785w, was further characterized as the product of a two-exon PHIST gene, and was more often recognized by serum samples from P. falciparum-exposed women than from men. CONCLUSIONS/SIGNIFICANCE These findings suggest that other parasite proteins, such as PFI1785w, may contribute beside VAR2CSA to the pathogenesis of PAM. These data may be very valuable for future vaccine development.
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Affiliation(s)
- Nicaise Tuikue Ndam
- Institut de Recherche pour le Développement, UR010 at Université Paris Descartes, Mother and Child Health in the Tropics, Faculté de Pharmacie, Paris, France.
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Touré FS, Ouwe-Missi-Oukem-Boyer O, Mezui-Me-Ndong J, Ndong-Atome GR, Bisvigou U, Mazier D, Bisser S. Cytoadherence and genotype of Plasmodium falciparum strains from symptomatic children in Franceville, southeastern Gabon. Clin Med Res 2007; 5:106-13. [PMID: 17607045 PMCID: PMC1905933 DOI: 10.3121/cmr.2007.696] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND Plasmodium falciparum causes severe clinical manifestations by sequestering parasitized red blood cells (PRBC) in the microvasculature of major organs such as the brain. This sequestration results from PRBC adherence to vascular endothelial cells via erythrocyte membrane protein 1, a variant parasite surface antigen. OBJECTIVE To determine whether P. falciparum multiple genotype infection (MGI) is associated with stronger PRBC cytoadherence and greater clinical severity. METHODS Nested polymerase chain reaction was used to genotype P. falciparum isolates from symptomatic children and to distinguish between single genotype infection (SGI) and MGI. PRBC cytoadhesion was studied with cultured human lung endothelial cells. RESULTS Analysis of two highly polymorphic regions of the merozoite surface antigen (MSP)-1 and MSP-2 genes and a dimorphic region of the erythrocyte binding antigen-175 gene showed that 21.4% and 78.6% of the 42 children had SGI and MGI, respectively. It also showed that 37 (89%) of the 42 PRBC samples expressed MSP-1 allelic family K1. Cytoadherence values ranged from 58 to 1811 PRBC/mm(2) of human lung endothelial cells monolayer in SGI and from 5 to 5744 PRBC/mm(2) in MGI. MGI was not associated with higher cytoadherence values or with more severe malaria. CONCLUSIONS These results suggested that infection of the same individual by multiple clones of P. falciparum does not significantly influence PRBC cytoadherence or disease severity and confirmed the predominance of the MSP-1 K1 genotype in southeastern Gabon.
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Affiliation(s)
- Fousseyni S Touré
- Centre International de Recherches, Médicales de Franceville, BP 769 Franceville, Gabon.
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Richie T. High road, low road? Choices and challenges on the pathway to a malaria vaccine. Parasitology 2007; 133 Suppl:S113-44. [PMID: 17274843 DOI: 10.1017/s0031182006001843] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Malaria causes much physical and economic hardship in endemic countries with billions of people at risk. A vaccine would clearly benefit these countries, reducing the requirement for hospital care and the economic impact of infection. Successful immunization with irradiated sporozoites and the fact that repeated exposure to malaria induces partial immunity to infection and high levels of protection against the clinical manifestations, suggest that a vaccine is feasible. Numerous candidate antigens have been identified but the vaccine, which has been promised to be 'just round the corner' for many years, remains elusive. The factors contributing to this frustratingly slow progress are discussed including gaps in the knowledge of host/parasite biology, methods to induce potent cell-mediated immune responses, the difficulties associated with defining immune correlates of protection and antigen production and delivery. Finally, the use of attenuated organism vaccines is discussed.
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Affiliation(s)
- T Richie
- Malaria Program, Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, Maryland 20910-7500, USA.
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24
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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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