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High Proportion of Genome-Wide Homology and Increased Pretreatment pvcrt Levels in Plasmodium vivax Late Recurrences: a Chloroquine Therapeutic Efficacy Study. Antimicrob Agents Chemother 2021; 65:e0009521. [PMID: 34031050 DOI: 10.1128/aac.00095-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chloroquine (CQ) is the first-line treatment for Plasmodium vivax malaria in most countries where malaria is endemic. Monitoring P. vivax CQ resistance (CQR) is critical but remains challenged by the difficulty to distinguish real treatment failure from reinfection or liver relapse. The therapeutic efficacy of CQ against uncomplicated P. vivax malaria was evaluated in Gia Lai Province, Vietnam. Sixty-seven patients were enrolled and followed for 42 days using microscopy and quantitative PCR. Adequate clinical and parasitological response (ACPR) was 100% (66/66) on day 28 but 75.4% (49/65) on day 42. Eighteen recurrences (27.7%) were detected, with a median time to recurrence of 42 days (interquartile range [IQR], 35 to 42) and blood CQ concentration of <100 ng/ml. Primary infections leading to recurrence occurred in younger individuals (median age for ACPR = 25 years [IQR, 20 to 28]; recurrences = 18 [16 to 21]; P = 0.002) had a longer parasite clearance time (PCT for ACPR = 47.5 h [IQR, 36.2 to 59.8 h]; recurrences = 54.2 [48.4 to 62.0]; P = 0.035) and higher pvcrt gene expression (median relative expression ratio for ACPR = 0.09 [IQR, 0.05 to 0.22]; recurrences = 0.20 [0.15 to 0.56]; P = 0.002), but showed no differences in ex vivo CQ sensitivity. Parasite genotyping by microsatellites, single nucleotide polymorphism (SNP) barcoding, and whole-genome sequencing (WGS) identified a majority of homologous recurrences, with 80% (8/10) showing >98% identity by descent to paired day 0 samples. This study shows that CQ remained largely efficacious to treat P. vivax in Gia Lai; i.e., recurrences occurred late (>day 28) and in the presence of low blood CQ concentrations. However, the combination of both WGS and gene expression analysis (pvcrt) data with clinical data (PCT) allowed us to identify potential emergence of low-grade CQR, which should be closely monitored. (This study has been registered at ClinicalTrials.gov under identifier NCT02610686.).
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Ferreira MU, Nobrega de Sousa T, Rangel GW, Johansen IC, Corder RM, Ladeia-Andrade S, Gil JP. Monitoring Plasmodium vivax resistance to antimalarials: Persisting challenges and future directions. Int J Parasitol Drugs Drug Resist 2021; 15:9-24. [PMID: 33360105 PMCID: PMC7770540 DOI: 10.1016/j.ijpddr.2020.12.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 11/27/2020] [Accepted: 12/01/2020] [Indexed: 11/23/2022]
Abstract
Emerging antimalarial drug resistance may undermine current efforts to control and eliminate Plasmodium vivax, the most geographically widespread yet neglected human malaria parasite. Endemic countries are expected to assess regularly the therapeutic efficacy of antimalarial drugs in use in order to adjust their malaria treatment policies, but proper funding and trained human resources are often lacking to execute relatively complex and expensive clinical studies, ideally complemented by ex vivo assays of drug resistance. Here we review the challenges for assessing in vivo P. vivax responses to commonly used antimalarials, especially chloroquine and primaquine, in the presence of confounding factors such as variable drug absorption, metabolism and interaction, and the risk of new infections following successful radical cure. We introduce a simple modeling approach to quantify the relative contribution of relapses and new infections to recurring parasitemias in clinical studies of hypnozoitocides. Finally, we examine recent methodological advances that may render ex vivo assays more practical and widely used to confirm P. vivax drug resistance phenotypes in endemic settings and review current approaches to the development of robust genetic markers for monitoring chloroquine resistance in P. vivax populations.
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Affiliation(s)
- Marcelo U Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil; Global Health and Tropical Medicine, Institute of Hygiene and Tropical Medicine, Nova University of Lisbon, Lisbon, Portugal.
| | - Tais Nobrega de Sousa
- Molecular Biology and Malaria Immunology Research Group, René Rachou Institute, Fiocruz, Belo Horizonte, Brazil
| | - Gabriel W Rangel
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA
| | - Igor C Johansen
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Rodrigo M Corder
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Simone Ladeia-Andrade
- Laboratory of Parasitic Diseases, Oswaldo Cruz Institute, Fiocruz, Rio de Janeiro, Brazil
| | - José Pedro Gil
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, Solna, Sweden
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Ford A, Kepple D, Abagero BR, Connors J, Pearson R, Auburn S, Getachew S, Ford C, Gunalan K, Miller LH, Janies DA, Rayner JC, Yan G, Yewhalaw D, Lo E. Whole genome sequencing of Plasmodium vivax isolates reveals frequent sequence and structural polymorphisms in erythrocyte binding genes. PLoS Negl Trop Dis 2020; 14:e0008234. [PMID: 33044985 PMCID: PMC7581005 DOI: 10.1371/journal.pntd.0008234] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 10/22/2020] [Accepted: 08/21/2020] [Indexed: 12/16/2022] Open
Abstract
Plasmodium vivax malaria is much less common in Africa than the rest of the world because the parasite relies primarily on the Duffy antigen/chemokine receptor (DARC) to invade human erythrocytes, and the majority of Africans are Duffy negative. Recently, there has been a dramatic increase in the reporting of P. vivax cases in Africa, with a high number of them being in Duffy negative individuals, potentially indicating P. vivax has evolved an alternative invasion mechanism that can overcome Duffy negativity. Here, we analyzed single nucleotide polymorphism (SNP) and copy number variation (CNV) in Whole Genome Sequence (WGS) data from 44 P. vivax samples isolated from symptomatic malaria patients in southwestern Ethiopia, where both Duffy positive and Duffy negative individuals are found. A total of 123,711 SNPs were detected, of which 22.7% were nonsynonymous and 77.3% were synonymous mutations. The largest number of SNPs were detected on chromosomes 9 (24,007 SNPs; 19.4% of total) and 10 (16,852 SNPs, 13.6% of total). There were particularly high levels of polymorphism in erythrocyte binding gene candidates including merozoite surface protein 1 (MSP1) and merozoite surface protein 3 (MSP3.5, MSP3.85 and MSP3.9). Two genes, MAEBL and MSP3.8 related to immunogenicity and erythrocyte binding function were detected with significant signals of positive selection. Variation in gene copy number was also concentrated in genes involved in host-parasite interactions, including the expansion of the Duffy binding protein gene (PvDBP) on chromosome 6 and MSP3.11 on chromosome 10. Based on the phylogeny constructed from the whole genome sequences, the expansion of these genes was an independent process among the P. vivax lineages in Ethiopia. We further inferred transmission patterns of P. vivax infections among study sites and showed various levels of gene flow at a small geographical scale. The genomic features of P. vivax provided baseline data for future comparison with those in Duffy-negative individuals and allowed us to develop a panel of informative Single Nucleotide Polymorphic markers diagnostic at a micro-geographical scale. Plasmodium vivax is the most geographically widespread parasite species that causes malaria in humans. Although it occurs in Africa as a member of a mix of Plasmodium species, P. vivax is dominant in other parts of the world outside of Africa (e.g., Brazil). It was previously thought that most African populations were immune to P. vivax infections due to the absence of Duffy antigen chemokine receptor (DARC) gene expression required for erythrocyte invasion. However, several recent reports have indicated the emergence and potential spread of P. vivax across human populations in Africa. Compared to Southeast Asia and South America where P. vivax is highly endemic, data on polymorphisms in erythrocyte binding gene candidates of P. vivax from Africa is limited. Filling this knowlege gap is critical for identifying functional genes in erythrocyte invasion, biomarkers for tracking the P. vivax isolates from Africa, as well as potential gene targets for vaccine development. This paper examined the level of genetic polymorphisms in a panel of 43 potential erythrocyte binding protein genes based on whole genome sequences and described transmission patterns of P. vivax infections from different study sites in Ethiopia based on the genetic variants. Our analyses showed that chromosomes 9 and 10 of the P. vivax genomes isolated in Ethiopia had the most high-quality genetic polymorphisms. Among all erythrocyte binding protein gene candidates, the merozoite surface proteins 1 and merozoite surface protein 3 showed high levels of polymorphism. MAEBL and MSP3.8 related to immunogenicity and erythrocyte binding function were detected with significant signals of positive selection. The expansion of the Duffy binding protein and merozoite surface protein 3 gene copies was an independent process among the P. vivax lineages in Ethiopia. Various levels of gene flow were observed even at a smaller geographical scale. Our study provided baseline data for future comparison with P. vivax in Duffy negative individuals and help develop a panel of genetic markers that are informative at a micro-geographical scale.
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Affiliation(s)
- Anthony Ford
- Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, United States of America
- Department of Biological Sciences, University of North Carolina at Charlotte, United States of America
- * E-mail: (AF); (GY); (EL)
| | - Daniel Kepple
- Department of Biological Sciences, University of North Carolina at Charlotte, United States of America
| | - Beka Raya Abagero
- Tropical Infectious Disease Research Center, Jimma University, Ethiopia
| | - Jordan Connors
- Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, United States of America
| | - Richard Pearson
- Malaria Programme, Wellcome Trust Sanger Institute, Hinxton, United States of America
| | - Sarah Auburn
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
| | - Sisay Getachew
- College of Natural Sciences, Addis Ababa University, Ethiopia
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Colby Ford
- Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, United States of America
| | - Karthigayan Gunalan
- Laboratory of Malaria and Vector Research, NIAID/NIH, Bethesda, United States of America
| | - Louis H. Miller
- Laboratory of Malaria and Vector Research, NIAID/NIH, Bethesda, United States of America
| | - Daniel A. Janies
- Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, United States of America
| | - Julian C. Rayner
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 OXY, United Kingdom
| | - Guiyun Yan
- Program in Public Health, University of California at Irvine, United States of America
- * E-mail: (AF); (GY); (EL)
| | | | - Eugenia Lo
- Department of Biological Sciences, University of North Carolina at Charlotte, United States of America
- * E-mail: (AF); (GY); (EL)
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Manrique P, Miranda-Alban J, Alarcon-Baldeon J, Ramirez R, Carrasco-Escobar G, Herrera H, Guzman-Guzman M, Rosas-Aguirre A, Llanos-Cuentas A, Vinetz JM, Escalante AA, Gamboa D. Microsatellite analysis reveals connectivity among geographically distant transmission zones of Plasmodium vivax in the Peruvian Amazon: A critical barrier to regional malaria elimination. PLoS Negl Trop Dis 2019; 13:e0007876. [PMID: 31710604 PMCID: PMC6874088 DOI: 10.1371/journal.pntd.0007876] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 11/21/2019] [Accepted: 10/25/2019] [Indexed: 12/31/2022] Open
Abstract
Despite efforts made over decades by the Peruvian government to eliminate malaria, Plasmodium vivax remains a challenge for public health decision-makers in the country. The uneven distribution of its incidence, plus its complex pattern of dispersion, has made ineffective control measures based on global information that lack the necessary detail to understand transmission fully. In this sense, population genetic tools can complement current surveillance. This study describes the genetic diversity and population structure from September 2012 to March 2015 in three geographically distant settlements, Cahuide (CAH), Lupuna (LUP) and Santa Emilia (STE), located in the Peruvian Amazon. A total 777 P. vivax mono-infections, out of 3264, were genotyped. Among study areas, LUP showed 19.7% of polyclonal infections, and its genetic diversity (Hexp) was 0.544. Temporal analysis showed a significant increment of polyclonal infections and Hexp, and the introduction and persistence of a new parasite population since March 2013. In STE, 40.1% of infections were polyclonal, with Hexp = 0.596. The presence of four genetic clusters without signals of clonal expansion and infections with lower parasite densities compared against the other two areas were also found. At least four parasite populations were present in CAH in 2012, where, after June 2014, malaria cases decreased from 213 to 61, concomitant with a decrease in polyclonal infections (from 0.286 to 0.18), and expectedly variable Hexp. Strong signals of gene flow were present in the study areas and wide geographic distribution of highly diverse parasite populations were found. This study suggests that movement of malaria parasites by human reservoirs connects geographically distant malaria transmission areas in the Peruvian Amazon. The maintenance of high levels of parasite genetic diversity through human mobility is a critical barrier to malaria elimination in this region. Plasmodium vivax transmission is heterogeneous and discontinuous in the Peruvian Amazon. Such heterogeneity is the result of factors that include, but are not restricted to, the environment, public policies, and characteristics of the parasite, the vector, and human activities. All these factors make P. vivax transmission resilient to interventions. In order to achieve the goals of control and local elimination, P. vivax surveillance must inform how those factors sustain disease transmission in order to focalize and synchronize control strategies. In this study, we implemented molecular surveillance complemented with population genetic tools in the areas of Cahuide, Lupuna, and Santa Emilia located in the Peruvian Amazon. In particular, we characterize the transmission and the parasite genetic variation in these sites from September 2012 to March 2015. The changes in parasite diversity, the wide geographic dispersion of parasite subpopulation and the introduction of a new parasite clone or subpopulation in Lupuna documented in this study suggest that connectivity among the different endemic areas, likely due to human mobility, sustains disease transmission in the region hindering the success of control measures. This information must be considered in the design of current control strategies.
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Affiliation(s)
- Paulo Manrique
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofa, Universidad Peruana Cayetano Heredia, Lima, Perú
- * E-mail:
| | - Julio Miranda-Alban
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofa, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Jhonatan Alarcon-Baldeon
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofa, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Roberson Ramirez
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofa, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Gabriel Carrasco-Escobar
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofa, Universidad Peruana Cayetano Heredia, Lima, Perú
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Henry Herrera
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofa, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Mitchel Guzman-Guzman
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofa, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Angel Rosas-Aguirre
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Perú
- Fund for Scientific Research FNRS, Brussels, Belgium
- Research Institute of Health and Society (IRSS), Université catholique de Louvain, Brussels, Belgium
| | - Alejandro Llanos-Cuentas
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Perú
- Facultad de Salud Pública y Administración, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Joseph M. Vinetz
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofa, Universidad Peruana Cayetano Heredia, Lima, Perú
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Perú
- Yale School of Medicine, Section of Infectious Diseases, Department of Internal Medicine, New Haven, Connecticut, United States of America
- Departamento de Ciencias Celulares y Moleculares, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Ananias A. Escalante
- Institute for Genomics and Evolutionary Medicine (IGEM), Temple University, Philadelphia, Pennsylvania, United States of America
| | - Dionicia Gamboa
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofa, Universidad Peruana Cayetano Heredia, Lima, Perú
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Perú
- Departamento de Ciencias Celulares y Moleculares, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú
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Humoral immunity prevents clinical malaria during Plasmodium relapses without eliminating gametocytes. PLoS Pathog 2019; 15:e1007974. [PMID: 31536608 PMCID: PMC6752766 DOI: 10.1371/journal.ppat.1007974] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 07/10/2019] [Indexed: 12/19/2022] Open
Abstract
Plasmodium relapses are attributed to the activation of dormant liver-stage parasites and are responsible for a significant number of recurring malaria blood-stage infections. While characteristic of human infections caused by P. vivax and P. ovale, their relative contribution to malaria disease burden and transmission remains poorly understood. This is largely because it is difficult to identify ‘bona fide’ relapse infections due to ongoing transmission in most endemic areas. Here, we use the P. cynomolgi–rhesus macaque model of relapsing malaria to demonstrate that clinical immunity can form after a single sporozoite-initiated blood-stage infection and prevent illness during relapses and homologous reinfections. By integrating data from whole blood RNA-sequencing, flow cytometry, P. cynomolgi-specific ELISAs, and opsonic phagocytosis assays, we demonstrate that this immunity is associated with a rapid recall response by memory B cells that expand and produce anti-parasite IgG1 that can mediate parasite clearance of relapsing parasites. The reduction in parasitemia during relapses was mirrored by a reduction in the total number of circulating gametocytes, but importantly, the cumulative proportion of gametocytes increased during relapses. Overall, this study reveals that P. cynomolgi relapse infections can be clinically silent in macaques due to rapid memory B cell responses that help to clear asexual-stage parasites but still carry gametocytes. Plasmodium vivax contributes significantly to global malaria morbidity and remains a major obstacle for malaria elimination due to its ability to form dormant stages in the liver. These forms can become activated to cause relapsing blood-stage infections. Relapses remain poorly understood because it is difficult to verify whether P. vivax blood-stage infections in patients are due to new infections or relapses in most cases. Here, we use a nonhuman primate model of Plasmodium vivax malaria in concert with state-of-the-art immunological and molecular techniques to assess pathogenesis, host responses, and circulating gametocyte levels during relapses. We found that relapses were clinically silent compared to initial infections, and they were associated with a robust memory B cell response. This response resulted in the production of antibodies that were able to mediate clearance of asexual parasites. Despite this rapid immune protection, the sexual-stage gametocytes continued to circulate. Our study provides mechanistic insights into the host-parasite interface during Plasmodium relapse infections and demonstrates that clinically silent relapses can harbor gametocytes that may be infectious to mosquitoes.
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Ventocilla JA, Nuñez J, Tapia LL, Lucas CM, Manock SR, Lescano AG, Edgel KA, Graf PCF. Genetic Variability of Plasmodium vivax in the North Coast of Peru and the Ecuadorian Amazon Basin. Am J Trop Med Hyg 2018; 99:27-32. [PMID: 29761758 DOI: 10.4269/ajtmh.17-0498] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
In the Peruvian North Coast (PNC), the number of Plasmodium vivax malaria cases increased steadily from 2007 to 2010 despite a significant decline in the overall number of cases in Peru during the same period. To better understand the transmission dynamics of P. vivax populations in the PNC and the neighboring Ecuadorian Amazon Basin (EAB), we studied the genetic variability and population structure of P. vivax in these areas. One hundred and twenty P. vivax isolates (58 from Piura and 37 from Tumbes in the PNC collected from 2008 to 2010 and 25 from the EAB collected in Pastaza from 2001 to 2004) were assessed by five polymorphic microsatellite markers. Genetic variability was determined by expected heterozygosity (He) and population structure by Bayesian inference cluster analysis. We found very low genetic diversity in the PNC (He = 0-0.32) but high genetic diversity in the EAB (He = 0.43-0.70). Population structure analysis revealed three distinct populations in the three locations. Six of 37 (16%) isolates from Tumbes had an identical haplotype to that found in Piura, suggesting unidirectional flow from Piura to Tumbes. In addition, one haplotype from Tumbes showed similarity to a haplotype found in Pastaza, suggesting that this could be an imported case from EAB. These findings strongly suggest a minimal population flow and different levels of genetic variability between these two areas divided by the Andes Mountains. This work presents molecular markers that could be used to increase our understanding of regional malaria transmission dynamics, which has implications for the development of strategies for P. vivax control.
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Affiliation(s)
| | - Jorge Nuñez
- U.S. Naval Medical Research Unit 6 (NAMRU-6), Lima, Peru
| | - L Lorena Tapia
- U.S. Naval Medical Research Unit 6 (NAMRU-6), Lima, Peru
| | - Carmen M Lucas
- U.S. Naval Medical Research Unit 6 (NAMRU-6), Lima, Peru
| | | | - Andrés G Lescano
- Emerge, Emerging Diseases and Climate Change Research Unit, School of Public Health and Administration Universidad Peruana Cayetano Heredia, Lima, Peru.,U.S. Naval Medical Research Unit 6 (NAMRU-6), Lima, Peru
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Zhong D, Koepfli C, Cui L, Yan G. Molecular approaches to determine the multiplicity of Plasmodium infections. Malar J 2018; 17:172. [PMID: 29685152 PMCID: PMC5914063 DOI: 10.1186/s12936-018-2322-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 04/18/2018] [Indexed: 12/26/2022] Open
Abstract
Multiplicity of infection (MOI), also termed complexity of infection (COI), is defined as the number of genetically distinct parasite strains co-infecting a single host, which is an important indicator of malaria epidemiology. PCR-based genotyping often underestimates MOI. Next generation sequencing technologies provide much more accurate and genome-wide characterization of polyclonal infections. However, complete haplotype characterization of multiclonal infections remains a challenge due to PCR artifacts and sequencing errors, and requires efficient computational tools. In this review, the advantages and limitations of current molecular approaches to determine multiplicity of malaria parasite infection are discussed.
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Affiliation(s)
- Daibin Zhong
- Program in Public Health, University of California, Irvine, CA, 92617, USA.
| | - Cristian Koepfli
- Program in Public Health, University of California, Irvine, CA, 92617, USA
| | - Liwang Cui
- Department of Entomology, Pennsylvania State University, University Park, PA, 16802, USA
| | - Guiyun Yan
- Program in Public Health, University of California, Irvine, CA, 92617, USA.
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Martin TCS, Vinetz JM. Asymptomatic Plasmodium vivax parasitaemia in the low-transmission setting: the role for a population-based transmission-blocking vaccine for malaria elimination. Malar J 2018; 17:89. [PMID: 29466991 PMCID: PMC5822557 DOI: 10.1186/s12936-018-2243-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 02/17/2018] [Indexed: 12/21/2022] Open
Abstract
Plasmodium vivax remains an important cause of morbidity and mortality across the Americas, Horn of Africa, East and South East Asia. Control of transmission has been hampered by emergence of chloroquine resistance and several intrinsic characteristics of infection including asymptomatic carriage, challenges with diagnosis, difficulty eradicating the carrier state and early gametocyte appearance. Complex human-parasite-vector immunological interactions may facilitate onward infection of mosquitoes. Given these challenges, new therapies are being explored including the development of transmission to mosquito blocking vaccines. Herein, the case supporting the need for transmission-blocking vaccines to augment control of P. vivax parasite transmission and explore factors that are limiting eradication efforts is discussed.
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Affiliation(s)
- Thomas C S Martin
- Division of Infectious Diseases, Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Joseph M Vinetz
- Division of Infectious Diseases, Department of Medicine, University of California San Diego, La Jolla, CA, USA.
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Lo E, Lam N, Hemming-Schroeder E, Nguyen J, Zhou G, Lee MC, Yang Z, Cui L, Yan G. Frequent Spread of Plasmodium vivax Malaria Maintains High Genetic Diversity at the Myanmar-China Border, Without Distance and Landscape Barriers. J Infect Dis 2017; 216:1254-1263. [PMID: 28329141 DOI: 10.1093/infdis/jix106] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 03/02/2017] [Indexed: 11/13/2022] Open
Abstract
Background In Myanmar, civil unrest and the establishment of internally displaced person (IDP) settlements along the Myanmar-China border have impacted malaria transmission. Methods Microsatellite markers were used to examine source-sink dynamics for Plasmodium vivax between IDP settlements and surrounding villages in the border region. Genotypic structure and diversity were compared across the 3 years following the establishment of IDP settlements, to infer demographic history. We investigated whether human migration and landscape heterogeneity contributed to P. vivax transmission. Results P. vivax from IDP settlements and local communities consistently exhibited high genetic diversity within populations but low polyclonality within individuals. No apparent genetic structure was observed among populations and years. P. vivax genotypes in China were similar to those in Myanmar, and parasite introduction was unidirectional. Landscape factors, including distance, elevation, and land cover, do not appear to impede parasite gene flow. Conclusions The admixture of P. vivax genotypes suggested that parasite gene flow via human movement contributes to the spread of malaria both locally in Myanmar and across the international border. Our genetic findings highlight the presence of large P. vivax gene reservoirs that can sustain transmission. Thus, it is important to reinforce and improve existing control efforts along border areas.
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Affiliation(s)
- Eugenia Lo
- Program in Public Health, University of California-Irvine
| | - Nancy Lam
- Program in Public Health, University of California-Irvine
| | | | | | - Guofa Zhou
- Program in Public Health, University of California-Irvine
| | - Ming-Chieh Lee
- Program in Public Health, University of California-Irvine
| | - Zhaoqing Yang
- Department of Pathogen Biology and Immunology, Kunming Medical University, China
| | - Liwang Cui
- Department of Entomology, Pennsylvania State University, University Park
| | - Guiyun Yan
- Program in Public Health, University of California-Irvine
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Soontarawirat I, Andolina C, Paul R, Day NPJ, Nosten F, Woodrow CJ, Imwong M. Plasmodium vivax genetic diversity and heterozygosity in blood samples and resulting oocysts at the Thai-Myanmar border. Malar J 2017; 16:355. [PMID: 28870214 PMCID: PMC5584506 DOI: 10.1186/s12936-017-2002-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 08/29/2017] [Indexed: 11/30/2022] Open
Abstract
Background Polyclonal blood-stage infections of Plasmodium vivax are frequent even in low transmission settings, allowing meiotic recombination between heterologous parasites. Empirical data on meiotic products are however lacking. This study examined microsatellites in oocysts derived by membrane feeding of mosquitoes from blood-stage P. vivax infections at the Thai–Myanmar border. Methods Blood samples from patients presenting with vivax malaria were fed to Anopheles cracens by membrane feeding and individual oocysts from midguts were obtained by dissection after 7 days. DNA was extracted from oocysts and parental blood samples and tested by microsatellite analysis. Results A focused study of eight microsatellite markers was undertaken for nine blood stage infections from 2013, for which derived oocysts were studied in six cases. One or more alleles were successfully amplified for 131 oocysts, revealing high levels of allelic diversity in both blood and oocyst stages. Based on standard criteria for defining minor alleles, there was evidence of clear deviation from random mating (inbreeding) with relatively few heterozygous oocysts compared to variance across the entire oocyst population (FIT = 0.89). The main explanation appeared to be natural compartmentalisation at mosquito (FSC = 0.27) and human stages (FCT = 0.68). One single human case produced a total of 431 successfully amplified loci (across 70 oocysts) that were homozygous and identical to parental alleles at all markers, indicating clonal infection and transmission. Heterozygous oocyst alleles were found at 15/176 (8.5%) successfully amplified loci in the other five cases. There was apparently reduced oocyst heterozygosity in individual oocysts compared to diversity within individual mosquitoes (FIS = 0.55), but this may simply reflect the difficulty of detecting minor alleles in oocysts, given the high rate of amplification failure. Inclusion of minor allele peaks (irrespective of height) when matching peaks were found in related blood or oocyst samples, added 11 minor alleles for 9 oocysts, increasing the number of heterozygous loci to 26/176 (14.8%; p = 0.096). Conclusion There was an apparently low level of heterozygous oocysts but this can be explained by a combination of factors: relatively low complexity of parental infection, natural compartmentalisation in humans and mosquitoes, and the methodological challenge of detecting minor alleles. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-2002-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ingfar Soontarawirat
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Chiara Andolina
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford, Old Road Campus, Oxford, UK
| | - Richard Paul
- Unité de Génétique Fonctionnelle Des Maladies Infectieuses, Institut Pasteur, 28 rue du Docteur Roux, 75724, Paris, France.,Centre National de la Recherche Scientifique, URA3012, 28 rue du Docteur Roux, 75724, Paris, France
| | - Nicholas P J Day
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford, Old Road Campus, Oxford, UK.,Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Francois Nosten
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford, Old Road Campus, Oxford, UK
| | - Charles J Woodrow
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford, Old Road Campus, Oxford, UK.,Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Mallika Imwong
- Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. .,Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
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11
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Lo E, Hemming-Schroeder E, Yewhalaw D, Nguyen J, Kebede E, Zemene E, Getachew S, Tushune K, Zhong D, Zhou G, Petros B, Yan G. Transmission dynamics of co-endemic Plasmodium vivax and P. falciparum in Ethiopia and prevalence of antimalarial resistant genotypes. PLoS Negl Trop Dis 2017; 11:e0005806. [PMID: 28746333 PMCID: PMC5546713 DOI: 10.1371/journal.pntd.0005806] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 08/07/2017] [Accepted: 07/13/2017] [Indexed: 11/19/2022] Open
Abstract
Ethiopia is one of the few African countries where Plasmodium vivax is co-endemic with P. falciparum. Malaria transmission is seasonal and transmission intensity varies mainly by landscape and climate. Although the recent emergence of drug resistant parasites presents a major issue to malaria control in Ethiopia, little is known about the transmission pathways of parasite species and prevalence of resistant markers. This study used microsatellites to determine population diversity and gene flow patterns of P. falciparum (N = 226) and P. vivax (N = 205), as well as prevalence of drug resistant markers to infer the impact of gene flow and existing malaria treatment regimes. Plasmodium falciparum indicated a higher rate of polyclonal infections than P. vivax. Both species revealed moderate genetic diversity and similar population structure. Populations in the northern highlands were closely related to the eastern Rift Valley, but slightly distinct from the southern basin area. Gene flow via human migrations between the northern and eastern populations were frequent and mostly bidirectional. Landscape genetic analyses indicated that environmental heterogeneity and geographical distance did not constrain parasite gene flow. This may partly explain similar patterns of resistant marker prevalence. In P. falciparum, a high prevalence of mutant alleles was detected in codons related to chloroquine (pfcrt and pfmdr1) and sulfadoxine-pyrimethamine (pfdhps and pfdhfr) resistance. Over 60% of the samples showed pfmdr1 duplications. Nevertheless, no mutation was detected in pfK13 that relates to artemisinin resistance. In P. vivax, while sequences of pvcrt-o were highly conserved and less than 5% of the samples showed pvmdr duplications, over 50% of the samples had pvmdr1 976F mutation. It remains to be tested if this mutation relates to chloroquine resistance. Monitoring the extent of malaria spread and markers of drug resistance is imperative to inform policy for evidence-based antimalarial choice and interventions. To effectively reduce malaria burden in Ethiopia, control efforts should focus on seasonal migrant populations.
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MESH Headings
- Adolescent
- Adult
- Aged
- Aged, 80 and over
- Antimalarials/pharmacology
- Child
- Child, Preschool
- Drug Resistance
- Endemic Diseases
- Ethiopia/epidemiology
- Female
- Gene Flow
- Genes, Protozoan
- Genetics, Population
- Genotype
- Humans
- Infant
- Infant, Newborn
- Malaria, Falciparum/epidemiology
- Malaria, Falciparum/parasitology
- Malaria, Falciparum/transmission
- Malaria, Vivax/epidemiology
- Malaria, Vivax/parasitology
- Malaria, Vivax/transmission
- Male
- Microsatellite Repeats
- Middle Aged
- Plasmodium falciparum/drug effects
- Plasmodium falciparum/genetics
- Plasmodium falciparum/isolation & purification
- Plasmodium vivax/drug effects
- Plasmodium vivax/genetics
- Plasmodium vivax/isolation & purification
- Prevalence
- Young Adult
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Affiliation(s)
- Eugenia Lo
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, North Carolina, United States of America
- * E-mail: (EL); (GY)
| | | | - Delenasaw Yewhalaw
- Department of Medical Laboratory Sciences and Pathology, College of Public Health and Medical Sciences, Jimma University, Jimma, Ethiopia
| | - Jennifer Nguyen
- Program in Public Health, University of California, Irvine, California, United States of America
| | - Estifanos Kebede
- Department of Medical Laboratory Sciences and Pathology, College of Public Health and Medical Sciences, Jimma University, Jimma, Ethiopia
| | - Endalew Zemene
- Department of Medical Laboratory Sciences and Pathology, College of Public Health and Medical Sciences, Jimma University, Jimma, Ethiopia
| | - Sisay Getachew
- College of Natural Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | - Kora Tushune
- Department of Health Services Management, College of Public Health and Medical Sciences, Jimma University, Jimma, Ethiopia
| | - Daibin Zhong
- Program in Public Health, University of California, Irvine, California, United States of America
| | - Guofa Zhou
- Program in Public Health, University of California, Irvine, California, United States of America
| | - Beyene Petros
- College of Natural Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | - Guiyun Yan
- Program in Public Health, University of California, Irvine, California, United States of America
- * E-mail: (EL); (GY)
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12
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Wang B, Nyunt MH, Yun SG, Lu F, Cheng Y, Han JH, Ha KS, Park WS, Hong SH, Lim CS, Cao J, Sattabongkot J, Kyaw MP, Cui L, Han ET. Variable number of tandem repeats of 9 Plasmodium vivax genes among Southeast Asian isolates. Acta Trop 2017; 170:161-168. [PMID: 28119047 DOI: 10.1016/j.actatropica.2017.01.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 01/12/2017] [Accepted: 01/16/2017] [Indexed: 02/01/2023]
Abstract
The variable number of tandem repeats (VNTRs) provides valuable information about both the functional and evolutionary aspects of genetic diversity. Comparative analysis of 3 Plasmodium falciparum genomes has shown that more than 9% of its open reading frames (ORFs) harbor VNTRs. Although microsatellites and VNTR genes of P. vivax were reported, the VNTR polymorphism of genes has not been examined widely. In this study, 230 P. vivax genes were analyzed for VNTRs by SERV, and 33 kinds of TR deletions or insertions from 29 P. vivax genes (12.6%) were found. Of these, 9 VNTR fragments from 8 P. vivax genes were used for PCR amplification and sequence analysis to examine the genetic diversity among 134 isolates from four Southeast Asian countries (China, Republic of Korea, Thailand, and Myanmar) with different malaria endemicity. We confirmed the existence of extensive polymorphism of VNTR fragments in field isolates. This detection provides several suitable markers for analysis of the molecular epidemiology of P. vivax field isolates.
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Affiliation(s)
- Bo Wang
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do 200-701, Republic of Korea; Department of Clinical Laboratory, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, People's Republic of China
| | - Myat Htut Nyunt
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do 200-701, Republic of Korea; Department of Medical Research, Yangon 11191, Myanmar
| | - Seung-Gyu Yun
- Department of Laboratory Medicine, College of Medicine, Korea University, Seoul 152-703, Republic of Korea
| | - Feng Lu
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do 200-701, Republic of Korea; Jiangsu Institute of Parasitic Diseases, Wuxi, Jiangsu 214064, People's Republic of China
| | - Yang Cheng
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do 200-701, Republic of Korea; Laboratory of Pathogen Infection and Immunity, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu 214122, People's Republic of China
| | - Jin-Hee Han
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do 200-701, Republic of Korea
| | - Kwon-Soo Ha
- Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do 200-701, Republic of Korea
| | - Won Sun Park
- Department of Physiology, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do 200-701, Republic of Korea
| | - Seok-Ho Hong
- Department of Internal Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do 200-701, Republic of Korea
| | - Chae-Seung Lim
- Department of Laboratory Medicine, College of Medicine, Korea University, Seoul 152-703, Republic of Korea
| | - Jun Cao
- Jiangsu Institute of Parasitic Diseases, Wuxi, Jiangsu 214064, People's Republic of China
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | | | - Liwang Cui
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do 200-701, Republic of Korea.
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13
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VivaxGEN: An open access platform for comparative analysis of short tandem repeat genotyping data in Plasmodium vivax populations. PLoS Negl Trop Dis 2017; 11:e0005465. [PMID: 28362818 PMCID: PMC5389845 DOI: 10.1371/journal.pntd.0005465] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 04/12/2017] [Accepted: 03/07/2017] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND The control and elimination of Plasmodium vivax will require a better understanding of its transmission dynamics, through the application of genotyping and population genetics analyses. This paper describes VivaxGEN (http://vivaxgen.menzies.edu.au), a web-based platform that has been developed to support P. vivax short tandem repeat data sharing and comparative analyses. RESULTS The VivaxGEN platform provides a repository for raw data generated by capillary electrophoresis (FSA files), with fragment analysis and standardized allele calling tools. The query system of the platform enables users to filter, select and differentiate samples and alleles based on their specified criteria. Key population genetic analyses are supported including measures of population differentiation (FST), expected heterozygosity (HE), linkage disequilibrium (IAS), neighbor-joining analysis and Principal Coordinate Analysis. Datasets can also be formatted and exported for application in commonly used population genetic software including GENEPOP, Arlequin and STRUCTURE. To date, data from 10 countries, including 5 publicly available data sets have been shared with VivaxGEN. CONCLUSIONS VivaxGEN is well placed to facilitate regional overviews of P. vivax transmission dynamics in different endemic settings and capable to be adapted for similar genetic studies of P. falciparum and other organisms.
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14
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Hamedi Y, Sharifi-Sarasiabi K, Dehghan F, Safari R, To S, Handayuni I, Trimarsanto H, Price RN, Auburn S. Molecular Epidemiology of P. vivax in Iran: High Diversity and Complex Sub-Structure Using Neutral Markers, but No Evidence of Y976F Mutation at pvmdr1. PLoS One 2016; 11:e0166124. [PMID: 27829067 PMCID: PMC5102416 DOI: 10.1371/journal.pone.0166124] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 10/24/2016] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Malaria remains endemic at low levels in the south-eastern provinces of Iran bordering Afghanistan and Pakistan, with the majority of cases attributable to P. vivax. The national guidelines recommend chloroquine (CQ) as blood-stage treatment for uncomplicated P. vivax, but the large influx of imported cases enhances the risk of introducing CQ resistance (CQR). METHODOLOGY AND PRINCIPAL FINDINGS The genetic diversity at pvmdr1, a putative modulator of CQR, and across nine putatively neutral short tandem repeat (STR) markers were assessed in P. vivax clinical isolates collected between April 2007 and January 2013 in Hormozgan Province, south-eastern Iran. One hundred blood samples were collected from patients with microscopy-confirmed P. vivax enrolled at one of five district clinics. In total 73 (73%) were autochthonous cases, 23 (23%) imported cases from Afghanistan or Pakistan, and 4 (4%) with unknown origin. 97% (97/100) isolates carried the F1076L mutation, but none carried the Y976F mutation. STR genotyping was successful in 71 (71%) isolates, including 57(57%) autochthonous and 11 (11%) imported cases. Analysis of population structure revealed 2 major sub-populations, K1 and K2, with further sub-structure within K2. The K1 sub-population had markedly lower diversity than K2 (HE = 0.06 vs HE = 0.82) suggesting that the sub-populations were sustained by distinct reservoirs with differing transmission dynamics, possibly reflecting local versus imported/introduced populations. No notable separation was observed between the local and imported cases although the sample size was limited. CONCLUSIONS The contrasting low versus high diversity in the two sub-populations (K1 and K2) infers that a combination of local transmission and cross-border malaria from higher transmission regions shape the genetic make-up of the P. vivax population in south-eastern Iran. There was no molecular evidence of CQR amongst the local or imported cases, but ongoing clinical surveillance is warranted.
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Affiliation(s)
- Yaghoob Hamedi
- Infectious and Tropical Diseases Research Center, Hormozgan University of Medical Sciences, Bandar Abbas, Hormozgan Province, Iran
| | - Khojasteh Sharifi-Sarasiabi
- Infectious and Tropical Diseases Research Center, Hormozgan University of Medical Sciences, Bandar Abbas, Hormozgan Province, Iran
| | - Farzaneh Dehghan
- Molecular Medicine Research Center, Hormozgan University of Medical Sciences, Bandar Abbas, Hormozgan Province, Iran
| | - Reza Safari
- Hormozgan University of Medical Sciences, Bandar Abbas, Hormozgan Province, Iran
| | - Sheren To
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
| | - Irene Handayuni
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
| | - Hidayat Trimarsanto
- Bioinformatics Laboratory, Eijkman Institute for Molecular Biology, Jakarta, Indonesia
- The Ministry of Research and Technology (RISTEK), Jakarta, Indonesia
- Agency for Assessment and Application of Technology, Jakarta, Indonesia
| | - Ric N. Price
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Sarah Auburn
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
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15
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Silvino ACR, Costa GL, de Araújo FCF, Ascher DB, Pires DEV, Fontes CJF, Carvalho LH, de Brito CFA, Sousa TN. Variation in Human Cytochrome P-450 Drug-Metabolism Genes: A Gateway to the Understanding of Plasmodium vivax Relapses. PLoS One 2016; 11:e0160172. [PMID: 27467145 PMCID: PMC4965052 DOI: 10.1371/journal.pone.0160172] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 07/14/2016] [Indexed: 01/08/2023] Open
Abstract
Although Plasmodium vivax relapses are classically associated with hypnozoite activation, it has been proposed that a proportion of these cases are due to primaquine (PQ) treatment failure caused by polymorphisms in cytochrome P-450 2D6 (CYP2D6). Here, we present evidence that CYP2D6 polymorphisms are implicated in PQ failure, which was reinforced by findings in genetically similar parasites, and may explain a number of vivax relapses. Using a computational approach, these polymorphisms were predicted to affect the activity of CYP2D6 through changes in the structural stability that could lead to disruption of the PQ-enzyme interactions. Furthermore, because PQ is co-administered with chloroquine (CQ), we investigated whether CQ-impaired metabolism by cytochrome P-450 2C8 (CYP2C8) could also contribute to vivax recurrences. Our results show that CYP2C8-mutated patients frequently relapsed early (<42 days) and had a higher proportion of genetically similar parasites, suggesting the possibility of recrudescence due to CQ therapeutic failure. These results highlight the importance of pharmacogenetic studies as a tool to monitor the efficacy of antimalarial therapy.
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Affiliation(s)
- Ana Carolina Rios Silvino
- Molecular Biology and Malaria Immunology Research Group, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Minas Gerais, Brazil
| | - Gabriel Luiz Costa
- Molecular Biology and Malaria Immunology Research Group, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Minas Gerais, Brazil
| | - Flávia Carolina Faustino de Araújo
- Molecular Biology and Malaria Immunology Research Group, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Minas Gerais, Brazil
| | - David Benjamin Ascher
- Biosystems Informatics Research Group, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Minas Gerais, Brazil
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Douglas Eduardo Valente Pires
- Biosystems Informatics Research Group, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Minas Gerais, Brazil
| | | | - Luzia Helena Carvalho
- Molecular Biology and Malaria Immunology Research Group, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Minas Gerais, Brazil
| | - Cristiana Ferreira Alves de Brito
- Molecular Biology and Malaria Immunology Research Group, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Minas Gerais, Brazil
| | - Tais Nobrega Sousa
- Molecular Biology and Malaria Immunology Research Group, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Minas Gerais, Brazil
- * E-mail:
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16
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Kim JY, Goo YK, Zo YG, Ji SY, Trimarsanto H, To S, Clark TG, Price RN, Auburn S. Further Evidence of Increasing Diversity of Plasmodium vivax in the Republic of Korea in Recent Years. PLoS One 2016; 11:e0151514. [PMID: 26990869 PMCID: PMC4798397 DOI: 10.1371/journal.pone.0151514] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 02/29/2016] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Vivax malaria was successfully eliminated from the Republic of Korea (ROK) in the late 1970s but re-emerged in 1993. Two decades later as the ROK enters the final stages of malaria elimination, dedicated surveillance of the local P. vivax population is critical. We apply a population genetic approach to gauge P. vivax transmission dynamics in the ROK between 2010 and 2012. METHODOLOGY/PRINCIPAL FINDINGS P. vivax positive blood samples from 98 autochthonous cases were collected from patients attending health centers in the ROK in 2010 (n = 27), 2011 (n = 48) and 2012 (n = 23). Parasite genotyping was undertaken at 9 tandem repeat markers. Although not reaching significance, a trend of increasing population diversity was observed from 2010 (HE = 0.50 ± 0.11) to 2011 (HE = 0.56 ± 0.08) and 2012 (HE = 0.60 ± 0.06). Conversely, linkage disequilibrium declined during the same period: IAS = 0.15 in 2010 (P = 0.010), 0.09 in 2011 (P = 0.010) and 0.05 in 2012 (P = 0.010). In combination with data from other ROK studies undertaken between 1994 and 2007, our results are consistent with increasing parasite divergence since re-emergence. Polyclonal infections were rare (3% infections) suggesting that local out-crossing alone was unlikely to explain the increased divergence. Cases introduced from an external reservoir may therefore have contributed to the increased diversity. Aside from one isolate, all infections carried a short MS20 allele (142 or 149 bp), not observed in other studies in tropical endemic countries despite high diversity, inferring that these regions are unlikely reservoirs. CONCLUSIONS Whilst a number of factors may explain the observed population genetic trends, the available evidence suggests that an external geographic reservoir with moderate diversity sustains the majority of P. vivax infection in the ROK, with important implications for malaria elimination.
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Affiliation(s)
- Jung-Yeon Kim
- Division of Malaria and Parasitic Diseases, National Institute of Health, Korea CDC, Osong Saeng-myeong, 2 ro, Osong Health Technology Administration, Osong, Republic of Korea
| | - Youn-Kyoung Goo
- Division of Malaria and Parasitic Diseases, National Institute of Health, Korea CDC, Osong Saeng-myeong, 2 ro, Osong Health Technology Administration, Osong, Republic of Korea
- Department of Parasitology and Tropical Medicine, Kyungpook National University School of Medicine, Daegu, 700–422, Republic of Korea
| | - Young-Gun Zo
- Department of Molecular Parasitology, Sungkyunkwan University School of Medicine and Center for Molecular Medicine, Samsung Biomedical Research Institute, Suwon, Gyeonggi-do 440–746, Republic of Korea
| | - So-Young Ji
- Division of Malaria and Parasitic Diseases, National Institute of Health, Korea CDC, Osong Saeng-myeong, 2 ro, Osong Health Technology Administration, Osong, Republic of Korea
| | - Hidayat Trimarsanto
- Eijkman Institute for Molecular Biology, Jl. Diponegoro 69, Jakarta Pusat, 10430, Indonesia
- Agency for Assessment and Application of Technology, Jl. MH Thamrin 8, Jakarta, 10340, Indonesia
| | - Sheren To
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, NT 0810, Australia
| | - Taane G. Clark
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, United Kingdom
- Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, United Kingdom
| | - Ric N. Price
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, NT 0810, Australia
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Sarah Auburn
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, NT 0810, Australia
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17
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Population Genetics of Plasmodium vivax in Four Rural Communities in Central Vietnam. PLoS Negl Trop Dis 2016; 10:e0004434. [PMID: 26872387 PMCID: PMC4752448 DOI: 10.1371/journal.pntd.0004434] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 01/14/2016] [Indexed: 12/03/2022] Open
Abstract
Background The burden of malaria in Vietnam has drastically reduced, prompting the National Malaria Control Program to officially engage in elimination efforts. Plasmodium vivax is becoming increasingly prevalent, remaining a major problem in the country's central and southern provinces. A better understanding of P. vivax genetic diversity and structure of local parasite populations will provide baseline data for the evaluation and improvement of current efforts for control and elimination. The aim of this study was to examine the population genetics and structure of P. vivax isolates from four communities in Tra Leng commune, Nam Tra My district in Quang Nam, Central Vietnam. Methodology/Principal Findings P. vivax mono infections collected from 234 individuals between April 2009 and December 2010 were successfully analyzed using a panel of 14 microsatellite markers. Isolates displayed moderate genetic diversity (He = 0.68), with no significant differences between study communities. Polyclonal infections were frequent (71.4%) with a mean multiplicity of infection of 1.91 isolates/person. Low but significant genetic differentiation (FST value from -0.05 to 0.18) was observed between the community across the river and the other communities. Strong linkage disequilibrium ( IAS = 0.113, p < 0.001) was detected across all communities, suggesting gene flow within and among them. Using multiple approaches, 101 haplotypes were grouped into two genetic clusters, while 60.4% of haplotypes were admixed. Conclusions/Significance In this area of Central Vietnam, where malaria transmission has decreased significantly over the past decade, there was moderate genetic diversity and high occurrence of polyclonal infections. Local human populations have frequent social and economic interactions that facilitate gene flow and inbreeding among parasite populations, while decreasing population structure. Findings provide important information on parasites populations circulating in the study area and are relevant to current malaria elimination efforts. In Vietnam, Plasmodium vivax (P. vivax) is the second most frequent human malaria parasite and a major obstacle to countrywide malaria elimination. Knowing the local parasite structure is useful for elimination efforts. Therefore, we analyzed, with a panel of 14 microsatellite markers, 234 P. vivax mono infections in blood samples collected from 4 communities in central Vietnam. Genetic diversity in the population was moderate; a high occurrence of polyclonal infections and significant linkage disequilibrium were detected, suggesting inbreeding or recombination between highly related haplotypes. In addition, both genetic differentiation and population structure was low and only detected between communities at each side of the river. Those results suggest gene flow between study communities with the river defining a moderate geographical barrier. Future studies should determine how this genetic variation is maintained in an area of extremely low transmission.
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Maneerattanasak S, Gosi P, Krudsood S, Tongshoob J, Lanteri CA, Snounou G, Khusmith S. Genetic diversity among Plasmodium vivax isolates along the Thai-Myanmar border of Thailand. Malar J 2016; 15:75. [PMID: 26858120 PMCID: PMC4746829 DOI: 10.1186/s12936-016-1136-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Accepted: 01/29/2016] [Indexed: 11/16/2022] Open
Abstract
Background Knowledge of the population genetics and transmission dynamics of Plasmodium vivax is crucial in predicting the emergence of drug resistance, relapse pattern and novel parasite phenotypes, all of which are relevant to the control of vivax infections. The aim of this study was to analyse changes in the genetic diversity of P. vivax genes from field isolates collected at different times along the Thai–Myanmar border. Methods Two hundred and fifty-four P. vivax isolates collected during two periods 10 years apart along the Thai–Myanmar border were analysed. The parasites were genotyped by nested-PCR and PCR–RFLP targeting selected polymorphic loci of Pvmsp1, Pvmsp3α and Pvcsp genes. Results The total number of distinguishable allelic variants observed for Pvcsp, Pvmsp1, and Pvmsp3α was 17, 7 and 3, respectively. High genetic diversity was observed for Pvcsp (HE = 0.846) and Pvmsp1 (HE = 0.709). Of the 254 isolates, 4.3 and 14.6 % harboured mixed Pvmsp1 and Pvcsp genotypes with a mean multiplicity of infection (MOI) of 1.06 and 1.15, respectively. The overall frequency of multiple genotypes was 16.9 %. When the frequencies of allelic variants of each gene during the two distinct periods were analysed, significant differences were noted for Pvmsp1 (P = 0.018) and the Pvcsp (P = 0.033) allelic variants. Conclusion Despite the low malaria transmission levels in Thailand, P. vivax population exhibit a relatively high degree of genetic diversity along the Thai–Myanmar border of Thailand, in particular for Pvmsp1 and Pvcsp, with indication of geographic and temporal variation in frequencies for some variants. These results are of relevance to monitoring the emergence of drug resistance and to the elaboration of measures to control vivax malaria.
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Affiliation(s)
- Sarunya Maneerattanasak
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Bangkok, 10400, Thailand.
| | - Panita Gosi
- Department of Immunology and Medicine, Armed Forces Research Institute of Medical Science-United States Army Military Component, Bangkok, Thailand.
| | - Srivicha Krudsood
- Clinical Malaria Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
| | - Jarinee Tongshoob
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Bangkok, 10400, Thailand.
| | - Charlotte A Lanteri
- Department of Immunology and Medicine, Armed Forces Research Institute of Medical Science-United States Army Military Component, Bangkok, Thailand.
| | - Georges Snounou
- UPMC UMRS CR7, Sorbonne Universités, UPMC Univ Paris 06, 75005, Paris, France. .,Institut National de la Santé et de la Recherche Médicale (Inserm) U1135 - Centre National de la Recherche Scientifique (CNRS) ERL 8255, Centre d'Immunologie et de Maladies Infectieuses (CIMI) - Paris, 75013, Paris, France.
| | - Srisin Khusmith
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Bangkok, 10400, Thailand. .,Center for Emerging and Neglected Infectious Diseases, Mahidol University, Bangkok, Thailand.
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Delgado-Ratto C, Gamboa D, Soto-Calle VE, Van den Eede P, Torres E, Sánchez-Martínez L, Contreras-Mancilla J, Rosanas-Urgell A, Rodriguez Ferrucci H, Llanos-Cuentas A, Erhart A, Van geertruyden JP, D’Alessandro U. Population Genetics of Plasmodium vivax in the Peruvian Amazon. PLoS Negl Trop Dis 2016; 10:e0004376. [PMID: 26766548 PMCID: PMC4713096 DOI: 10.1371/journal.pntd.0004376] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 12/18/2015] [Indexed: 11/18/2022] Open
Abstract
Background Characterizing the parasite dynamics and population structure provides useful information to understand the dynamic of transmission and to better target control interventions. Despite considerable efforts for its control, vivax malaria remains a major health problem in Peru. In this study, we have explored the population genetics of Plasmodium vivax isolates from Iquitos, the main city in the Peruvian Amazon, and 25 neighbouring peri-urban as well as rural villages along the Iquitos-Nauta Road. Methodology/ Results From April to December 2008, 292 P. vivax isolates were collected and successfully genotyped using 14 neutral microsatellites. Analysis of the molecular data revealed a similar proportion of monoclonal and polyclonal infections in urban areas, while in rural areas monoclonal infections were predominant (p = 0.002). Multiplicity of infection was higher in urban (MOI = 1.5–2) compared to rural areas (MOI = 1) (p = 0.003). The level of genetic diversity was similar in all areas (He = 0.66–0.76, p = 0.32) though genetic differentiation between areas was substantial (PHIPT = 0.17, p<0.0001). Principal coordinate analysis showed a marked differentiation between parasites from urban and rural areas. Linkage disequilibrium was detected in all the areas ( IAs = 0.08–0.49, for all p<0.0001). Gene flow among the areas was stablished through Bayesian analysis of migration models. Recent bottleneck events were detected in 4 areas and a recent parasite expansion in one of the isolated areas. In total, 87 unique haplotypes grouped in 2 or 3 genetic clusters described a sub-structured parasite population. Conclusion/Significance Our study shows a sub-structured parasite population with clonal propagation, with most of its components recently affected by bottleneck events. Iquitos city is the main source of parasite spreading for all the peripheral study areas. The routes of transmission and gene flow and the reduction of the parasite population described are important from the public health perspective as well for the formulation of future control policies. We present the population genetics of malaria vivax parasites in a large area of the Peruvian Amazon. Our results showed that the parasite population had a predominant clonal propagation, reproducing themselves with identically or closely related parasites; therefore, the same genetic characteristics are maintained in the offspring. The clonal propagation may favour the higher levels of genetic differentiation among the parasites from isolated areas compared to areas where human migration is common. The patterns of gene flow have been established, finding Iquitos city as a reservoir of parasite genetic variability. Moreover, a recent reduction of the parasite population was observed in areas where recent control activities were performed. This research provides a picture of the nature and dynamics of the parasite population which have a significant impact in the malaria epidemiology; therefore, this knowledge is crucial for the development of efficient control policies.
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Affiliation(s)
| | - Dionicia Gamboa
- Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
- Departamento de Ciencias Celulares y Moleculares, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Veronica E. Soto-Calle
- Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Peter Van den Eede
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Eliana Torres
- Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Luis Sánchez-Martínez
- Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Juan Contreras-Mancilla
- Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Anna Rosanas-Urgell
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | | | - Alejandro Llanos-Cuentas
- Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Annette Erhart
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | | | - Umberto D’Alessandro
- Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium
- Medical Research Council Unit, Fajara, The Gambia
- London School of Hygiene and Tropical Medicine, London, United Kingdom
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20
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Variation in Complexity of Infection and Transmission Stability between Neighbouring Populations of Plasmodium vivax in Southern Ethiopia. PLoS One 2015; 10:e0140780. [PMID: 26468643 PMCID: PMC4607408 DOI: 10.1371/journal.pone.0140780] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 09/30/2015] [Indexed: 12/21/2022] Open
Abstract
Background P. vivax is an important public health burden in Ethiopia, accounting for almost half of all malaria cases. Owing to heterogeneous transmission across the country, a stronger evidence base on local transmission dynamics is needed to optimise allocation of resources and improve malaria interventions. Methodology and Principal Findings In a pilot evaluation of local level P. vivax molecular surveillance in southern Ethiopia, the diversity and population structure of isolates collected between May and November 2013 were investigated. Blood samples were collected from microscopy positive P. vivax patients recruited to clinical and cross-sectional surveys from four sites: Arbaminch, Halaba, Badawacho and Hawassa. Parasite genotyping was undertaken at nine tandem repeat markers. Eight loci were successfully genotyped in 197 samples (between 36 and 59 per site). Heterogeneity was observed in parasite diversity and structure amongst the sites. Badawacho displayed evidence of unstable transmission, with clusters of identical clonal infections. Linkage disequilibrium in Badawacho was higher (IAS = 0.32, P = 0.010) than in the other populations (IAS range = 0.01–0.02) and declined markedly after adjusting for identical infections (IAS = 0.06, P = 0.010). Other than Badawacho (HE = 0.70), population diversity was equivalently high across the sites (HE = 0.83). Polyclonal infections were more frequent in Hawassa (67%) than the other populations (range: 8–44%). Despite the variable diversity, differentiation between the sites was low (FST range: 5 x 10−3–0.03). Conclusions Marked variation in parasite population structure likely reflects differing local transmission dynamics. Parasite genotyping in these heterogeneous settings has potential to provide important complementary information with which to optimise malaria control interventions.
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de Souza AM, de Araújo FCF, Fontes CJF, Carvalho LH, de Brito CFA, de Sousa TN. Multiple-clone infections of Plasmodium vivax: definition of a panel of markers for molecular epidemiology. Malar J 2015; 14:330. [PMID: 26303668 PMCID: PMC4548710 DOI: 10.1186/s12936-015-0846-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 08/11/2015] [Indexed: 11/10/2022] Open
Abstract
Background Plasmodium vivax infections commonly contain multiple genetically distinct parasite clones. The detection of multiple-clone infections depends on several factors, such as the accuracy of the genotyping method, and the type and number of the molecular markers analysed. Characterizing the multiplicity of infection has broad implications that range from population genetic studies of the parasite to malaria treatment and control. This study compared and evaluated the efficiency of neutral and non-neutral markers that are widely used in studies of molecular epidemiology to detect the multiplicity of P. vivax infection. Methods The performance of six markers was evaluated using 11 mixtures of DNA with well-defined proportions of two different parasite genotypes for each marker. These mixtures were generated by mixing cloned PCR products or patient-derived genomic DNA. In addition, 51 samples of natural infections from the Brazil were genotyped for all markers. The PCR-capillary electrophoresis-based method was used to permit direct comparisons among the markers. The criteria for differentiating minor peaks from artifacts were also evaluated. Results The analysis of DNA mixtures showed that the tandem repeat MN21 and the polymorphic blocks 2 (msp1B2) and 10 (msp1B10) of merozoite surface protein-1 allowed for the estimation of the expected ratio of both alleles in the majority of preparations. Nevertheless, msp1B2 was not able to detect the majority of multiple-clone infections in field samples; it identified only 6 % of these infections. The merozoite surface protein-3 alpha and microsatellites (PvMS6 and PvMS7) did not accurately estimate the relative clonal proportions in artificial mixtures, but the microsatellites performed well in detecting natural multiple-clone infections. Notably, the use of a less stringent criterion to score rare alleles significantly increased the sensitivity of the detection of multi-clonal infections. Conclusions Depending on the type of marker used, a considerable amplification bias was observed, which may have serious implications for the characterization of the complexity of a P. vivax infection. Based on the performance of markers in artificial mixtures of DNA and natural infections, a minimum panel of four genetic markers (PvMS6, PvMS7, MN21, and msp1B10) was defined, and these markers are highly informative regarding the genetic variability of P. vivax populations. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0846-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Aracele M de Souza
- Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Minas Gerais, Brazil.
| | - Flávia C F de Araújo
- Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Minas Gerais, Brazil.
| | - Cor J F Fontes
- Hospital Julio Muller, Universidade Federal de Mato Grosso, Cuiabá, Mato Grosso, Brazil.
| | - Luzia H Carvalho
- Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Minas Gerais, Brazil.
| | - Cristiana F A de Brito
- Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Minas Gerais, Brazil.
| | - Taís N de Sousa
- Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Minas Gerais, Brazil.
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Manrique P, Hoshi M, Fasabi M, Nolasco O, Yori P, Calderón M, Gilman RH, Kosek MN, Vinetz JM, Gamboa D. Assessment of an automated capillary system for Plasmodium vivax microsatellite genotyping. Malar J 2015; 14:326. [PMID: 26293655 PMCID: PMC4546211 DOI: 10.1186/s12936-015-0842-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 08/08/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Several platforms have been used to generate the primary data for microsatellite analysis of malaria parasite genotypes. Each has relative advantages but share a limitation of being time- and cost-intensive. A commercially available automated capillary gel cartridge system was assessed in the microsatellite analysis of Plasmodium vivax diversity in the Peruvian Amazon. METHODS The reproducibility and accuracy of a commercially-available automated capillary system, QIAxcel, was assessed using a sequenced PCR product of 227 base pairs. This product was measured 42 times, then 27 P. vivax samples from Peruvian Amazon subjects were analyzed with this instrument using five informative microsatellites. Results from the QIAxcel system were compared with a Sanger-type sequencing machine, the ABI PRISM(®) 3100 Genetic Analyzer. RESULTS Significant differences were seen between the sequenced amplicons and the results from the QIAxcel instrument. Different runs, plates and cartridges yielded significantly different results. Additionally, allele size decreased with each run by 0.045, or 1 bp, every three plates. QIAxcel and ABI PRISM systems differed in giving different values than those obtained by ABI PRISM, and too many (i.e. inaccurate) alleles per locus were also seen with the automated instrument. CONCLUSIONS While P. vivax diversity could generally be estimated using an automated capillary gel cartridge system, the data demonstrate that this system is not sufficiently precise for reliably identifying parasite strains via microsatellite analysis. This conclusion reached after systematic analysis was due both to inadequate precision and poor reproducibility in measuring PCR product size.
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Affiliation(s)
- Paulo Manrique
- Malaria Laboratory, Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.
| | - Mari Hoshi
- Malaria Laboratory, Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.
| | | | - Oscar Nolasco
- Malaria Laboratory, Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.
| | - Pablo Yori
- Department of International Health, Johns Hopkins School of Public Health, Baltimore, MD, USA.
| | - Martiza Calderón
- Division of Infectious Diseases, Department of Medicine, University of California San Diego, La Jolla, CA, USA.
| | - Robert H Gilman
- Department of International Health, Johns Hopkins School of Public Health, Baltimore, MD, USA.
| | - Margaret N Kosek
- Department of International Health, Johns Hopkins School of Public Health, Baltimore, MD, USA.
| | - Joseph M Vinetz
- Malaria Laboratory, Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru. .,Division of Infectious Diseases, Department of Medicine, University of California San Diego, La Jolla, CA, USA.
| | - Dionicia Gamboa
- Malaria Laboratory, Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru. .,Departamento de Ciencias Celulares y Moleculares, Universidad Peruana Cayetano Heredia, Lima, Peru.
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23
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Flannery EL, Wang T, Akbari A, Corey VC, Gunawan F, Bright AT, Abraham M, Sanchez JF, Santolalla ML, Baldeviano GC, Edgel KA, Rosales LA, Lescano AG, Bafna V, Vinetz JM, Winzeler EA. Next-Generation Sequencing of Plasmodium vivax Patient Samples Shows Evidence of Direct Evolution in Drug-Resistance Genes. ACS Infect Dis 2015; 1:367-79. [PMID: 26719854 DOI: 10.1021/acsinfecdis.5b00049] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Understanding the mechanisms of drug resistance in Plasmodium vivax, the parasite that causes the most widespread form of human malaria, is complicated by the lack of a suitable long-term cell culture system for this parasite. In contrast to P. falciparum, which can be more readily manipulated in the laboratory, insights about parasite biology need to be inferred from human studies. Here we analyze the genomes of parasites within 10 human P. vivax infections from the Peruvian Amazon. Using next-generation sequencing we show that some P. vivax infections analyzed from the region are likely polyclonal. Despite their polyclonality we observe limited parasite genetic diversity by showing that three or fewer haplotypes comprise 94% of the examined genomes, suggesting the recent introduction of parasites into this geographic region. In contrast we find more than three haplotypes in putative drug-resistance genes, including the gene encoding dihydrofolate reductase-thymidylate synthase and the P. vivax multidrug resistance associated transporter, suggesting that resistance mutations have arisen independently. Additionally, several drug-resistance genes are located in genomic regions with evidence of increased copy number. Our data suggest that whole genome sequencing of malaria parasites from patients may provide more insight about the evolution of drug resistance than genetic linkage or association studies, especially in geographical regions with limited parasite genetic diversity.
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Affiliation(s)
| | | | | | | | | | | | | | - Juan F. Sanchez
- U.S. Naval Medical Research Unit No. 6 (NAMRU-6), Avenida Venezuela Cuadra 36 S/N, Centro Médico
Naval, Lima Callao 02, Peru
| | - Meddly L. Santolalla
- U.S. Naval Medical Research Unit No. 6 (NAMRU-6), Avenida Venezuela Cuadra 36 S/N, Centro Médico
Naval, Lima Callao 02, Peru
| | - G. Christian Baldeviano
- U.S. Naval Medical Research Unit No. 6 (NAMRU-6), Avenida Venezuela Cuadra 36 S/N, Centro Médico
Naval, Lima Callao 02, Peru
| | - Kimberly A. Edgel
- U.S. Naval Medical Research Unit No. 6 (NAMRU-6), Avenida Venezuela Cuadra 36 S/N, Centro Médico
Naval, Lima Callao 02, Peru
| | - Luis A. Rosales
- U.S. Naval Medical Research Unit No. 6 (NAMRU-6), Avenida Venezuela Cuadra 36 S/N, Centro Médico
Naval, Lima Callao 02, Peru
| | - Andrés G. Lescano
- U.S. Naval Medical Research Unit No. 6 (NAMRU-6), Avenida Venezuela Cuadra 36 S/N, Centro Médico
Naval, Lima Callao 02, Peru
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Koepfli C, Rodrigues PT, Antao T, Orjuela-Sánchez P, Van den Eede P, Gamboa D, van Hong N, Bendezu J, Erhart A, Barnadas C, Ratsimbasoa A, Menard D, Severini C, Menegon M, Nour BYM, Karunaweera N, Mueller I, Ferreira MU, Felger I. Plasmodium vivax Diversity and Population Structure across Four Continents. PLoS Negl Trop Dis 2015; 9:e0003872. [PMID: 26125189 PMCID: PMC4488360 DOI: 10.1371/journal.pntd.0003872] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 06/02/2015] [Indexed: 01/12/2023] Open
Abstract
Plasmodium vivax is the geographically most widespread human malaria parasite. To analyze patterns of microsatellite diversity and population structure across countries of different transmission intensity, genotyping data from 11 microsatellite markers was either generated or compiled from 841 isolates from four continents collected in 1999–2008. Diversity was highest in South-East Asia (mean allelic richness 10.0–12.8), intermediate in the South Pacific (8.1–9.9) Madagascar and Sudan (7.9–8.4), and lowest in South America and Central Asia (5.5–7.2). A reduced panel of only 3 markers was sufficient to identify approx. 90% of all haplotypes in South Pacific, African and SE-Asian populations, but only 60–80% in Latin American populations, suggesting that typing of 2–6 markers, depending on the level of endemicity, is sufficient for epidemiological studies. Clustering analysis showed distinct clusters in Peru and Brazil, but little sub-structuring was observed within Africa, SE-Asia or the South Pacific. Isolates from Uzbekistan were exceptional, as a near-clonal parasite population was observed that was clearly separated from all other populations (FST>0.2). Outside Central Asia FST values were highest (0.11–0.16) between South American and all other populations, and lowest (0.04–0.07) between populations from South-East Asia and the South Pacific. These comparisons between P. vivax populations from four continents indicated that not only transmission intensity, but also geographical isolation affect diversity and population structure. However, the high effective population size results in slow changes of these parameters. This persistency must be taken into account when assessing the impact of control programs on the genetic structure of parasite populations. Plasmodium vivax is the predominant malaria parasite in Latin America, Asia and the South Pacific. Different factors are expected to shape diversity and population structure across continents, e.g. transmission intensity which is much lower in South America as compared to Southeast-Asia and the South Pacific, or geographical isolation of P. vivax populations in the South Pacific. We have compiled data from 841 isolates from South and Central America, Africa, Central Asia, Southeast-Asia and the South Pacific typed with a panel of 11 microsatellite markers. Diversity was highest in Southeast-Asia, where transmission is intermediate-high and migration of infected hosts is high, and lowest in South America and Central Asia where malaria transmission is low and focal. Reducing the panel of microsatellites showed that 2–6 markers are sufficient for genotyping for most drug trials and epidemiological studies, as these markers can identify >90% of all haplotypes. Parasites clustered according to continental origin, with high population differentiation between South American and Central Asian populations and the other populations, and lowest differences between Southeast-Asia and the South Pacific. Current attempts to reduce malaria transmission might change this pattern, but only after transmission is reduced for an extended period of time.
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Affiliation(s)
- Cristian Koepfli
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- Walter and Eliza Hall Institute, Parkville, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Priscila T. Rodrigues
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Tiago Antao
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Pamela Orjuela-Sánchez
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Peter Van den Eede
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Dionicia Gamboa
- Instituto de Medicina Tropical Alexander Von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Nguyen van Hong
- National Institute of Malariology, Parasitology, and Entomology, Hanoi, Vietnam
| | - Jorge Bendezu
- Instituto de Medicina Tropical Alexander Von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Annette Erhart
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Céline Barnadas
- Walter and Eliza Hall Institute, Parkville, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Arsène Ratsimbasoa
- Immunology Unit, Institut Pasteur de Madagascar, Antananarivo, Madagascar
| | - Didier Menard
- Institut Pasteur de Cambodge, Malaria Molecular Epidemiology Unit, Phnom Penh, Cambodia
| | - Carlo Severini
- Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Michela Menegon
- Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Bakri Y. M. Nour
- Department of Parasitology, Blue Nile National Institute for Communicable Diseases, University of Gezira, Wad Medani, Sudan
| | - Nadira Karunaweera
- Department of Parasitology, Faculty of Medicine, University of Colombo, Sri Lanka
| | - Ivo Mueller
- Walter and Eliza Hall Institute, Parkville, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
- Barcelona Centre for International Health Research, Barcelona, Spain
| | - Marcelo U. Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Ingrid Felger
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- * E-mail:
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25
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Contrasting Transmission Dynamics of Co-endemic Plasmodium vivax and P. falciparum: Implications for Malaria Control and Elimination. PLoS Negl Trop Dis 2015; 9:e0003739. [PMID: 25951184 PMCID: PMC4423885 DOI: 10.1371/journal.pntd.0003739] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 04/05/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Outside of Africa, P. falciparum and P. vivax usually coexist. In such co-endemic regions, successful malaria control programs have a greater impact on reducing falciparum malaria, resulting in P. vivax becoming the predominant species of infection. Adding to the challenges of elimination, the dormant liver stage complicates efforts to monitor the impact of ongoing interventions against P. vivax. We investigated molecular approaches to inform the respective transmission dynamics of P. falciparum and P. vivax and how these could help to prioritize public health interventions. METHODOLOGY/PRINCIPAL FINDINGS Genotype data generated at 8 and 9 microsatellite loci were analysed in 168 P. falciparum and 166 P. vivax isolates, respectively, from four co-endemic sites in Indonesia (Bangka, Kalimantan, Sumba and West Timor). Measures of diversity, linkage disequilibrium (LD) and population structure were used to gauge the transmission dynamics of each species in each setting. Marked differences were observed in the diversity and population structure of P. vivax versus P. falciparum. In Bangka, Kalimantan and Timor, P. falciparum diversity was low, and LD patterns were consistent with unstable, epidemic transmission, amenable to targeted intervention. In contrast, P. vivax diversity was higher and transmission appeared more stable. Population differentiation was lower in P. vivax versus P. falciparum, suggesting that the hypnozoite reservoir might play an important role in sustaining local transmission and facilitating the spread of P. vivax infections in different endemic settings. P. vivax polyclonality varied with local endemicity, demonstrating potential utility in informing on transmission intensity in this species. CONCLUSIONS/SIGNIFICANCE Molecular approaches can provide important information on malaria transmission that is not readily available from traditional epidemiological measures. Elucidation of the transmission dynamics circulating in a given setting will have a major role in prioritising malaria control strategies, particularly against the relatively neglected non-falciparum species.
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Barry AE, Waltmann A, Koepfli C, Barnadas C, Mueller I. Uncovering the transmission dynamics of Plasmodium vivax using population genetics. Pathog Glob Health 2015; 109:142-52. [PMID: 25891915 DOI: 10.1179/2047773215y.0000000012] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Population genetic analysis of malaria parasites has the power to reveal key insights into malaria epidemiology and transmission dynamics with the potential to deliver tools to support control and elimination efforts. Analyses of parasite genetic diversity have suggested that Plasmodium vivax populations are more genetically diverse and less structured than those of Plasmodium falciparum indicating that P. vivax may be a more ancient parasite of humans and/or less susceptible to population bottlenecks, as well as more efficient at disseminating its genes. These population genetic insights into P. vivax transmission dynamics provide an explanation for its relative resilience to control efforts. Here, we describe current knowledge on P. vivax population genetic structure, its relevance to understanding transmission patterns and relapse and how this information can inform malaria control and elimination programmes.
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Key Words
- Control,
- Elimination
- Genetic diversity,
- Genetics,
- Genomics,
- Linkage disequilibrium,
- Malaria,
- Microsatellites,
- Mitochondrial DNA,
- Plasmodium vivax,
- Population structure,
- Relapse,
- Single nucleotide polymorphisms,
- Transmission,
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27
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Baniecki ML, Faust AL, Schaffner SF, Park DJ, Galinsky K, Daniels RF, Hamilton E, Ferreira MU, Karunaweera ND, Serre D, Zimmerman PA, Sá JM, Wellems TE, Musset L, Legrand E, Melnikov A, Neafsey DE, Volkman SK, Wirth DF, Sabeti PC. Development of a single nucleotide polymorphism barcode to genotype Plasmodium vivax infections. PLoS Negl Trop Dis 2015; 9:e0003539. [PMID: 25781890 PMCID: PMC4362761 DOI: 10.1371/journal.pntd.0003539] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 01/15/2015] [Indexed: 12/30/2022] Open
Abstract
Plasmodium vivax, one of the five species of Plasmodium parasites that cause human malaria, is responsible for 25–40% of malaria cases worldwide. Malaria global elimination efforts will benefit from accurate and effective genotyping tools that will provide insight into the population genetics and diversity of this parasite. The recent sequencing of P. vivax isolates from South America, Africa, and Asia presents a new opportunity by uncovering thousands of novel single nucleotide polymorphisms (SNPs). Genotyping a selection of these SNPs provides a robust, low-cost method of identifying parasite infections through their unique genetic signature or barcode. Based on our experience in generating a SNP barcode for P. falciparum using High Resolution Melting (HRM), we have developed a similar tool for P. vivax. We selected globally polymorphic SNPs from available P. vivax genome sequence data that were located in putatively selectively neutral sites (i.e., intergenic, intronic, or 4-fold degenerate coding). From these candidate SNPs we defined a barcode consisting of 42 SNPs. We analyzed the performance of the 42-SNP barcode on 87 P. vivax clinical samples from parasite populations in South America (Brazil, French Guiana), Africa (Ethiopia) and Asia (Sri Lanka). We found that the P. vivax barcode is robust, as it requires only a small quantity of DNA (limit of detection 0.3 ng/μl) to yield reproducible genotype calls, and detects polymorphic genotypes with high sensitivity. The markers are informative across all clinical samples evaluated (average minor allele frequency > 0.1). Population genetic and statistical analyses show the barcode captures high degrees of population diversity and differentiates geographically distinct populations. Our 42-SNP barcode provides a robust, informative, and standardized genetic marker set that accurately identifies a genomic signature for P. vivax infections. Plasmodium vivax malaria is a major global public health problem, with nearly 2.5 billion people at risk for infection and approximately 132–391 million clinical infections annually. It has a wide geographical range, with a high disease burden in Asia, Central and South America, the Middle East, Oceania, and East Africa. Advances in sequencing technology and sample processing have made it possible to characterize the genetic diversity of P. vivax populations. This genetic variation provides a means to identify parasites by unique genetic signatures, or “barcodes.” We developed such a genetic barcode for P. vivax, composed of 42 robust and informative variants. Here we report its development and validation based on 87 clinical samples identified by microscopy to contain P. vivax from geographically diverse parasite populations from South America (Brazil, French Guiana), Africa (Ethiopia) and Asia (Sri Lanka). We show that the SNP barcode provides a genotyping tool that can be performed at low cost, providing a means to uniquely identify parasite infections and distinguish geographic origins, and that barcode data may offer new insights into P. vivax population structure and diversity.
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Affiliation(s)
- Mary Lynn Baniecki
- Broad Institute, Cambridge, Massachusetts, United States of America
- * E-mail:
| | - Aubrey L. Faust
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | | | - Daniel J. Park
- Broad Institute, Cambridge, Massachusetts, United States of America
| | - Kevin Galinsky
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Rachel F. Daniels
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | - Elizabeth Hamilton
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | | | - Nadira D. Karunaweera
- Department of Parasitology, Faculty of Medicine, University of Colombo, Colombo, Sri Lanka
| | - David Serre
- Department of Genomic Medicine Institute, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, United States of America
| | - Peter A. Zimmerman
- Department of International Health, Biology and Genetics, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Juliana M. Sá
- Laboratory of Malaria and Vector Research, Malaria Genetics Section, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, United States of America
| | - Thomas E. Wellems
- Laboratory of Malaria and Vector Research, Malaria Genetics Section, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, United States of America
| | - Lise Musset
- Department of Parasitology, Institute Pasteur de la Guyane, Cayenne, French Guiana
| | - Eric Legrand
- Department of Parasitology, Institute Pasteur de la Guyane, Cayenne, French Guiana
| | | | | | - Sarah K. Volkman
- Broad Institute, Cambridge, Massachusetts, United States of America
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America
- School of Nursing and Health Sciences, Simmons College, Boston, Massachusetts, United States of America
| | - Dyann F. Wirth
- Broad Institute, Cambridge, Massachusetts, United States of America
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Pardis C. Sabeti
- Broad Institute, Cambridge, Massachusetts, United States of America
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America
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Menegon M, Durand P, Menard D, Legrand E, Picot S, Nour B, Davidyants V, Santi F, Severini C. Genetic diversity and population structure of Plasmodium vivax isolates from Sudan, Madagascar, French Guiana and Armenia. INFECTION GENETICS AND EVOLUTION 2014; 27:244-9. [PMID: 25102032 DOI: 10.1016/j.meegid.2014.07.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 07/25/2014] [Accepted: 07/28/2014] [Indexed: 10/24/2022]
Abstract
Polymorphic genetic markers and especially microsatellite analysis can be used to investigate multiple aspects of the biology of Plasmodium species. In the current study, we characterized 7 polymorphic microsatellites in a total of 281 Plasmodium vivax isolates to determine the genetic diversity and population structure of P. vivax populations from Sudan, Madagascar, French Guiana, and Armenia. All four parasite populations were highly polymorphic with 3-32 alleles per locus. Mean genetic diversity values was 0.83, 0.79, 0.78 and 0.67 for Madagascar, French Guiana, Sudan, and Armenia, respectively. Significant genetic differentiation between all four populations was observed.
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Affiliation(s)
- Michela Menegon
- Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanità, Rome, Italy.
| | - Patrick Durand
- Laboratoire MIVEGEC, UMR 224-5290 CNRS-IRD-UM1-UM2, IRD, Montpellier, France
| | - Didier Menard
- Malaria Molecular Epidemiology Unit, Pasteur Institute in Cambodia, Phnom Penh, Cambodia
| | - Eric Legrand
- National Reference Centre of Malaria Chemoresistance in French Guiana and West Indies, Institut Pasteur de la Guyane, Cayenne, French Guiana
| | - Stéphane Picot
- Malaria Research Unit, CNRS UMR 5246, Faculté de Médecine, Université Lyon 1, Lyon, France
| | - Bakri Nour
- Department of Parasitology, Blue Nile National Institute for Communicable Diseases, University of Gezira, Wad Medani, Sudan
| | - Vladimir Davidyants
- Department of Epidemiology and Health Informatics, Armenian National Institute of Health, Yerevan, Armenia
| | - Flavia Santi
- Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Carlo Severini
- Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanità, Rome, Italy
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Genetic diversity of Plasmodium vivax over time and space: a community-based study in rural Amazonia. Parasitology 2014; 142:374-84. [PMID: 25068581 DOI: 10.1017/s0031182014001176] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
To examine how community-level genetic diversity of the malaria parasite Plasmodium vivax varies across time and space, we investigated the dynamics of parasite polymorphisms during the early phases of occupation of a frontier settlement in the Amazon Basin of Brazil. Microsatellite characterization of 84 isolates of P. vivax sampled over 3 years revealed a moderate-to-high genetic diversity (mean expected heterozygosity, 0.699), with a large proportion (78.5%) of multiple-clone infections (MCI), but also a strong multilocus linkage disequilibrium (LD) consistent with rare outcrossing. Little temporal and no spatial clustering was observed in the distribution of parasite haplotypes. A single microsatellite haplotype was shared by 3 parasites collected during an outbreak; all other 81 haplotypes were recovered only once. The lowest parasite diversity, with the smallest proportion of MCI and the strongest LD, was observed at the time of the outbreak, providing a clear example of epidemic population structure in a human pathogen. Population genetic parameters returned to pre-outbreak values during last 2 years of study, despite the concomitant decline in malaria incidence. We suggest that parasite genotyping can be useful for tracking the spread of new parasite strains associated with outbreaks in areas approaching malaria elimination.
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30
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Liu Y, Auburn S, Cao J, Trimarsanto H, Zhou H, Gray KA, Clark TG, Price RN, Cheng Q, Huang R, Gao Q. Genetic diversity and population structure of Plasmodium vivax in Central China. Malar J 2014; 13:262. [PMID: 25008859 PMCID: PMC4094906 DOI: 10.1186/1475-2875-13-262] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 06/29/2014] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND In Central China the declining incidence of Plasmodium vivax has been interrupted by epidemic expansions and imported cases. The impact of these changes on the local parasite population, and concurrent risks of future resurgence, was assessed. METHODS Plasmodium vivax isolates collected from Anhui and Jiangsu provinces, Central China between 2007 and 2010 were genotyped using capillary electrophoresis at seven polymorphic short tandem repeat markers. Spatial and temporal analyses of within-host and population diversity, population structure, and relatedness were conducted on these isolates. RESULTS Polyclonal infections were infrequent in the 94 isolates from Anhui (4%) and 25 from Jiangsu (12%), with a trend for increasing frequency from 2008 to 2010 (2 to 19%) when combined. Population diversity was high in both provinces and across the years tested (H(E) = 0.8 - 0.85). Differentiation between Anhui and Jiangsu was modest (F'(ST) = 0.1). Several clusters of isolates with identical multi-locus haplotypes were observed across both Anhui and Jiangsu. Linkage disequilibrium was strong in both populations and in each year tested (I(A)(S) = 0.2 - 0.4), but declined two- to four-fold when identical haplotypes were accounted for, indicative of occasional epidemic transmission dynamics. None of five imported isolates shared identical haplotypes to any of the central Chinese isolates. CONCLUSIONS The population genetic structure of P. vivax in Central China highlights unstable transmission, with limited barriers to gene flow between the central provinces. Despite low endemicity, population diversity remained high, but the reservoirs sustaining this diversity remain unclear. The challenge of imported cases and risks of resurgence emphasize the need for continued surveillance to detect early warning signals. Although parasite genotyping has potential to inform the management of outbreaks, further studies are required to identify suitable marker panels for resolving local from imported P. vivax isolates.
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Affiliation(s)
- Yaobao Liu
- Medical College of Soochow University, Suzhou, Jiangsu, People’s Republic of China
- Jiangsu Institute of Parasitic Diseases, Key Laboratory of Parasitic Disease Control and Prevention (Ministry of Health), Jiangsu Provincial Key Laboratory of Parasite Molecular Biology, Wuxi, Jiangsu, People’s Republic of China
| | - Sarah Auburn
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
| | - Jun Cao
- Jiangsu Institute of Parasitic Diseases, Key Laboratory of Parasitic Disease Control and Prevention (Ministry of Health), Jiangsu Provincial Key Laboratory of Parasite Molecular Biology, Wuxi, Jiangsu, People’s Republic of China
| | | | - Huayun Zhou
- Jiangsu Institute of Parasitic Diseases, Key Laboratory of Parasitic Disease Control and Prevention (Ministry of Health), Jiangsu Provincial Key Laboratory of Parasite Molecular Biology, Wuxi, Jiangsu, People’s Republic of China
| | - Karen-Ann Gray
- Drug Resistance and Diagnostics, Australian Army Malaria Institute, Weary Dunlop Drive, Gallipoli Barracks, Enoggera, Queensland, Australia
| | - Taane G Clark
- Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Ric N Price
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Qin Cheng
- Drug Resistance and Diagnostics, Australian Army Malaria Institute, Weary Dunlop Drive, Gallipoli Barracks, Enoggera, Queensland, Australia
| | - Rui Huang
- Medical College of Soochow University, Suzhou, Jiangsu, People’s Republic of China
| | - Qi Gao
- Jiangsu Institute of Parasitic Diseases, Key Laboratory of Parasitic Disease Control and Prevention (Ministry of Health), Jiangsu Provincial Key Laboratory of Parasite Molecular Biology, Wuxi, Jiangsu, People’s Republic of China
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McCollum AM, Soberon V, Salas CJ, Santolalla ML, Udhayakumar V, Escalante AA, Graf PCF, Durand S, Cabezas C, Bacon DJ. Genetic variation and recurrent parasitaemia in Peruvian Plasmodium vivax populations. Malar J 2014; 13:67. [PMID: 24568141 PMCID: PMC3941685 DOI: 10.1186/1475-2875-13-67] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Accepted: 02/13/2014] [Indexed: 11/12/2022] Open
Abstract
Background Plasmodium vivax is a predominant species of malaria in parts of South America and there is increasing resistance to drugs to treat infections by P. vivax. The existence of latent hypnozoites further complicates the ability to classify recurrent infections as treatment failures due to relapse, recrudescence of hyponozoites or re-infections. Antigen loci are putatively under natural selection and may not be an optimal molecular marker to define parasite haplotypes in paired samples. Putatively neutral microsatellite loci, however, offer an assessment of neutral haplotypes. The objective here was to assess the utility of neutral microsatellite loci to reconcile cases of recurrent parasitaemia in Amazonian P. vivax populations in Peru. Methods Patient blood samples were collected from three locations in or around Iquitos in the Peruvian Amazon. Five putatively neutral microsatellite loci were characterized from 445 samples to ascertain the within and amongst population variation. A total of 30 day 0 and day of recurrent parasitaemia samples were characterized at microsatellite loci and five polymorphic antigen loci for haplotype classification. Results The genetic diversity at microsatellite loci was consistent with neutral levels of variation measured in other South American P. vivax populations. Results between antigen and microsatellite loci for the 30 day 0 and day of recurrent parasitaemia samples were the same for 80% of the pairs. The majority of non-concordant results were the result of differing alleles at microsatellite loci. This analysis estimates that 90% of the paired samples with the same microsatellite haplotype are unlikely to be due to a new infection. Conclusions A population-level approach was used to yield a better estimate of the probability of a new infection versus relapse or recrudescence of homologous hypnozoites; hypnozoite activation was common for this cohort. Population studies are critical with the evaluation of genetic markers to assess P. vivax biology and epidemiology. The additional demonstration of microsatellite loci as neutral markers capable of distinguishing the origin of the recurrent parasites (new infection or originating from the patient) lends support to their use in assessment of treatment outcomes.
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Affiliation(s)
- Andrea M McCollum
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA.
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Multilocus microsatellite genotyping array for investigation of genetic epidemiology of Pneumocystis jirovecii. J Clin Microbiol 2014; 52:1391-9. [PMID: 24523468 DOI: 10.1128/jcm.02531-13] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Pneumocystis jirovecii is a symbiotic respiratory fungus that causes pneumonia (PcP) in immunosuppressed patients. Because P. jirovecii cannot be reliably cultured in vitro, it has proven difficult to study and gaps in our understanding of the organism persist. The release of a draft genome for the organism opens the door for the development of new genotyping approaches for studying its molecular epidemiology and global population structure. We identified and validated 8 putatively neutral microsatellite markers and 1 microsatellite marker linked to the dihydropteroate synthase gene (dhps), the enzymatic target of sulfa drugs used for PcP prevention and treatment. Using these tools, we analyzed P. jirovecii isolates from HIV-infected patients from three geographically distant populations: Uganda, the United States, and Spain. Among the 8 neutral markers, we observed high levels of allelic heterozygosity (average He, 0.586 to 0.842). Consistent with past reports, we observed limited global population structuring, with only the Ugandan isolates showing minor differentiation from the other two populations. In Ugandan isolates that harbored mutations in dhps, the microsatellite locus linked to dhps demonstrated a depressed He, consistent with positive directional selection for sulfa resistance mutations. Using a subset of these microsatellites, analyses of individual and paired samples from infections in San Francisco, CA, showed reliable typeability within a single infection and high discriminatory power between infections. These features suggest that this novel microsatellite typing approach will be an effective tool for molecular-epidemiological investigations into P. jirovecii population structure, transmission, and drug resistance.
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Delgado-Ratto C, Soto-Calle VE, Van den Eede P, Gamboa D, Rosas A, Abatih EN, Rodriguez Ferrucci H, Llanos-Cuentas A, Van Geertruyden JP, Erhart A, D'Alessandro U. Population structure and spatio-temporal transmission dynamics of Plasmodium vivax after radical cure treatment in a rural village of the Peruvian Amazon. Malar J 2014; 13:8. [PMID: 24393454 PMCID: PMC3893378 DOI: 10.1186/1475-2875-13-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 12/28/2013] [Indexed: 11/23/2022] Open
Abstract
Background Despite the large burden of Plasmodium vivax, little is known about its transmission dynamics. This study explored the population structure and spatio-temporal dynamics of P. vivax recurrent infections after radical cure in a two-year cohort study carried out in a rural community of the Peruvian Amazon. Methods A total of 37 P. vivax participants recruited in San Carlos community (Peru) between April and December 2008 were treated radically with chloroquine and primaquine and followed up monthly for two years with systematic blood sampling. All samples were screened for malaria parasites and subsequently all P. vivax infections genotyped using 15 microsatellites. Parasite population structure and dynamics were determined by computing different genetic indices and using spatio-temporal statistics. Results After radical cure, 76% of the study participants experienced one or more recurrent P. vivax infections, most of them sub-patent and asymptomatic. The parasite population displayed limited genetic diversity (He = 0.49) and clonal structure, with most infections (84%) being monoclonal. Spatio-temporal clusters of specific haplotypes were found throughout the study and persistence of highly frequent haplotypes were observed over several months within the same participants/households. Conclusions In San Carlos community, P. vivax recurrences were commonly observed after radical treatment, and characterized by asymptomatic, sub-patent and clustered infections (within and between individuals from a few neighbouring households). Moreover low genetic diversity as well as parasite inbreeding are likely to define a clonal parasite population which has important implications on the malaria epidemiology of the study area.
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Affiliation(s)
- Christopher Delgado-Ratto
- Unit of International Health, ESOC Department, Faculty of Medicine, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium.
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Plasmodium vivax population structure and transmission dynamics in Sabah Malaysia. PLoS One 2013; 8:e82553. [PMID: 24358203 PMCID: PMC3866266 DOI: 10.1371/journal.pone.0082553] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2013] [Accepted: 10/27/2013] [Indexed: 11/19/2022] Open
Abstract
Despite significant progress in the control of malaria in Malaysia, the complex transmission dynamics of P. vivax continue to challenge national efforts to achieve elimination. To assess the impact of ongoing interventions on P. vivax transmission dynamics in Sabah, we genotyped 9 short tandem repeat markers in a total of 97 isolates (8 recurrences) from across Sabah, with a focus on two districts, Kota Marudu (KM, n = 24) and Kota Kinabalu (KK, n = 21), over a 2 year period. STRUCTURE analysis on the Sabah-wide dataset demonstrated multiple sub-populations. Significant differentiation (FST = 0.243) was observed between KM and KK, located just 130 Km apart. Consistent with low endemic transmission, infection complexity was modest in both KM (mean MOI = 1.38) and KK (mean MOI = 1.19). However, population diversity remained moderate (HE = 0.583 in KM and HE = 0.667 in KK). Temporal trends revealed clonal expansions reflecting epidemic transmission dynamics. The haplotypes of these isolates declined in frequency over time, but persisted at low frequency throughout the study duration. A diverse array of low frequency isolates were detected in both KM and KK, some likely reflecting remnants of previous expansions. In accordance with clonal expansions, high levels of Linkage Disequilibrium (IAS >0.5 [P<0.0001] in KK and KM) declined sharply when identical haplotypes were represented once (IAS = 0.07 [P = 0.0076] in KM, and IAS = -0.003 [P = 0.606] in KK). All 8 recurrences, likely to be relapses, were homologous to the prior infection. These recurrences may promote the persistence of parasite lineages, sustaining local diversity. In summary, Sabah's shrinking P. vivax population appears to have rendered this low endemic setting vulnerable to epidemic expansions. Migration may play an important role in the introduction of new parasite strains leading to epidemic expansions, with important implications for malaria elimination.
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Sutton PL. A call to arms: on refining Plasmodium vivax microsatellite marker panels for comparing global diversity. Malar J 2013; 12:447. [PMID: 24330329 PMCID: PMC3878832 DOI: 10.1186/1475-2875-12-447] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 12/06/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Microsatellite (MS) markers have become an important tool for studying the population diversity, evolutionary history and multiplicity of infection (MOI) of malaria parasite infections. MS are typically selected on the basis of being highly polymorphic. However, it is known that the polymorphic potential (mutability) of each marker can vary as much as two orders of magnitude, which radically changes how diversity is represented in the genome from one marker to the next. Over the past decade, approximately 240 Plasmodium vivax MS have been published, comprising nine major panels of markers. Inconsistent usage of each panel has resulted in a surfeit of descriptive genetic diversity data that are largely incomparable between populations. The objective of this study was to statistically evaluate the quality of individual MS markers in order to validate a refined panel of markers that will provide a balanced picture of P. vivax population diversity. METHODS All previously published data, including genetic diversity indices, MS parameters, and population parameters, were assembled from 18 different global studies into a flat file to facilitate statistical analysis and modelling using JMP® Genomics 6.0 (SAS Institute Inc, Cary, NC, USA). Statistical modeling was employed to down-select markers with extreme variation among the mean number of alleles, expected heterozygosity, maximum repeat length and/or chromosomal location of the repeat. Individual MS were analysed by step-down whole model linear regression and standard least squares fit models, both stratified by annual parasite incidence to identify MS markers with values significantly different from the mean. RESULTS Of the 42 MS under evaluation in this study, 18 (nine high priority) were identified as ideal candidates for measuring population diversity between global regions, while five (two high priority) additional markers were identified as candidates for MOI studies. CONCLUSIONS MS diversity was found to be a function of endemicity and motif structure. Evaluation of individual MS permitted the assembly of a refined panel of markers that can be reliably utilized in the field to compare population structures between global regions.
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Affiliation(s)
- Patrick L Sutton
- Center for Genomics and Systems Biology, Department of Biology, New York University, 12 Waverly Place, New York, NY 10003, USA.
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Arnott A, Barnadas C, Senn N, Siba P, Mueller I, Reeder JC, Barry AE. High genetic diversity of Plasmodium vivax on the north coast of Papua New Guinea. Am J Trop Med Hyg 2013; 89:188-94. [PMID: 23690553 DOI: 10.4269/ajtmh.12-0774] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Despite having the highest Plasmodium vivax burden in the world, molecular epidemiological data from Papua New Guinea (PNG) for this parasite remain limited. To investigate the molecular epidemiology of P. vivax in PNG, 574 isolates collected from four catchment sites in East Sepik (N = 1) and Madang (N = 3) Provinces were genotyped using the markers MS16 and msp1F3. Genetic diversity and prevalence of P. vivax was determined for all sites. Despite a P. vivax infection prevalence in the East Sepik (15%) catchments less than one-half the prevalence of the Madang catchments (27-35%), genetic diversity was similarly high in all populations (He = 0.77-0.98). High genetic diversity, despite a marked difference in infection prevalence, suggests a large reservoir of diversity in P. vivax populations of PNG. Significant reductions in transmission intensity may, therefore, be required to reduce the diversity of parasite populations in highly endemic countries such as PNG.
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Affiliation(s)
- Alicia Arnott
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia.
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Orjuela-Sánchez P, Sá JM, Brandi MCC, Rodrigues PT, Bastos MS, Amaratunga C, Duong S, Fairhurst RM, Ferreira MU. Higher microsatellite diversity in Plasmodium vivax than in sympatric Plasmodium falciparum populations in Pursat, Western Cambodia. Exp Parasitol 2013; 134:318-26. [PMID: 23562882 DOI: 10.1016/j.exppara.2013.03.029] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 03/22/2013] [Accepted: 03/25/2013] [Indexed: 11/25/2022]
Abstract
Previous microsatellite analyses of sympatric populations of Plasmodium vivax and Plasmodium falciparum in Brazil revealed higher diversity in the former species. However, it remains unclear whether regional species-specific differences in prevalence and transmission levels might account for these findings. Here, we examine sympatric populations of P. vivax (n=87) and P. falciparum (n=164) parasites from Pursat province, Western Cambodia, where both species are similarly prevalent. Using 10 genome-wide microsatellites for P. falciparum and 13 for P. vivax, we found that the P. vivax population was more diverse than the sympatric P. falciparum population (average virtual heterozygosity [HE], 0.87 vs. 0.66, P=0.003), with more multiple-clone infections (89.6% vs. 47.6%) and larger mean number of alleles per marker (16.2 vs. 11.1, P=0.07). Both populations showed significant multi-locus linkage disequilibrium suggestive of a predominantly clonal mode of parasite reproduction. The higher microsatellite diversity found in P. vivax isolates, compared to sympatric P. falciparum isolates, does not necessarily result from local differences in transmission level and may reflect differences in population history between species or increased mutation rates in P. vivax.
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Affiliation(s)
- Pamela Orjuela-Sánchez
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
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Verhave JP. Experimental, therapeutic and natural transmission of Plasmodium vivax tertian malaria: scientific and anecdotal data on the history of Dutch malaria studies. Parasit Vectors 2013; 6:19. [PMID: 23332002 PMCID: PMC3556107 DOI: 10.1186/1756-3305-6-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 01/11/2013] [Indexed: 11/30/2022] Open
Abstract
When Plasmodium vivax tertian malaria was prevalent in The Netherlands, the use of therapeutic malaria for the treatment of neurosyphilis patients presented an opportunity for biological studies of the parasite’s behaviour, in healthy volunteers. One unexplained phenomenon was the long latency between natural exposure to a single infected mosquito and the appearance of clinical signs (average 8 months). Dutch studies with volunteers and syphilis patients, suggested that hundreds of sporozoites transmitted by several mosquito bites were enough to provoke an early attack, known from tropical vivax-malaria. Sporozoites appeared to be programmed either to delay their pre-erythrocytic development or to proceed to an early attack within three weeks. The number of infectious bites also determined the relapse rate and the number of relapses after a primary attack. Analyses of primary cases and relapses from the previous year were used to predict the incidence for the next year. These historic findings fit well with recent studies on genotyping of blood stages during primary attacks and relapses. External factors (i.e. the milieu inside the human host) may trigger hypnozoites to reactivate, but predetermined periods of latency should also be considered.
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Affiliation(s)
- Jan Peter Verhave
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, 6500 HB, The Netherlands.
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Orjuela-Sánchez P, Brandi MC, Ferreira MU. Microsatellite analysis of malaria parasites. Methods Mol Biol 2013; 1006:247-58. [PMID: 23546796 DOI: 10.1007/978-1-62703-389-3_17] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Microsatellites have been increasingly used to investigate the population structure of malaria parasites, to map genetic loci contributing to phenotypes such as drug resistance and virulence in laboratory crosses and genome-wide association studies and to distinguish between treatment failures and new infections in clinical trials. Here, we provide optimized protocols for genotyping highly polymorphic microsatellites sampled from across the genomes of the human malaria parasites Plasmodium falciparum and P. vivax that have been extensively used in research laboratories worldwide.
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Affiliation(s)
- Pamela Orjuela-Sánchez
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
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de Araujo FCF, de Rezende AM, Fontes CJF, Carvalho LH, Alves de Brito CF. Multiple-clone activation of hypnozoites is the leading cause of relapse in Plasmodium vivax infection. PLoS One 2012. [PMID: 23185469 PMCID: PMC3503861 DOI: 10.1371/journal.pone.0049871] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Background Plasmodium vivax infection is characterized by a dormant hepatic stage, the hypnozoite that is activated at varying periods of time after clearance of the primary acute blood-stage, resulting in relapse. Differentiation between treatment failure and new infections requires characterization of initial infections, relapses, and clone multiplicity in vivax malaria infections. Methodology/Principal Findings Parasite DNA obtained from primary/relapse paired blood samples of 30 patients with P. vivax infection in Brazil was analyzed using 10 molecular markers (8 microsatellites and MSP-1 blocks 2 and 10). Cloning of PCR products and genotyping was used to identify low-frequency clones of parasites. We demonstrated a high frequency of multiple-clone infections in both primary and relapse infections. Few alleles were identified per locus, but the combination of these alleles produced many haplotypes. Consequently, the majority of parasites involved in relapse showed haplotypes that were distinct from those of primary infections. Plasmodium vivax relapse was characterized by temporal variations in the predominant parasite clones. Conclusions/Significance The high rate of low frequency alleles observed in both primary and relapse infections, along with temporal variation in the predominant alleles, might be the source of reported heterologous hypnozoite activation. Our findings complicate the concept of heterologous activation, suggesting the involvement of undetermined mechanisms based on host or environmental factors in the simultaneous activation of multiple clones of hypnozoites.
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Affiliation(s)
| | - Antônio Mauro de Rezende
- Laboratory of Cellular and Molecular Parasitology, Centro de Pesquisas René Rachou – Fiocruz Minas, Belo Horizonte, Minas Gerais, Brazil
| | | | - Luzia Helena Carvalho
- Laboratory of Malaria, Centro de Pesquisas René Rachou – Fiocruz Minas, Belo Horizonte, Minas Gerais, Brazil
| | - Cristiana F. Alves de Brito
- Laboratory of Malaria, Centro de Pesquisas René Rachou – Fiocruz Minas, Belo Horizonte, Minas Gerais, Brazil
- * E-mail:
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Guimarães LO, Bajay MM, Wunderlich G, Bueno MG, Röhe F, Catão-Dias JL, Neves A, Malafronte RS, Curado I, Kirchgatter K. The genetic diversity of Plasmodium malariae and Plasmodium brasilianum from human, simian and mosquito hosts in Brazil. Acta Trop 2012; 124:27-32. [PMID: 22705349 DOI: 10.1016/j.actatropica.2012.05.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 05/29/2012] [Accepted: 05/31/2012] [Indexed: 11/28/2022]
Abstract
Plasmodium malariae is a protozoan parasite that causes malaria in humans and is genetically indistinguishable from Plasmodium brasilianum, a parasite infecting New World monkeys in Central and South America. P. malariae has a wide and patchy global distribution in tropical and subtropical regions, being found in South America, Asia, and Africa. However, little is known regarding the genetics of these parasites and the similarity between them could be because until now there are only a very few genomic sequences available from simian Plasmodium species. This study presents the first molecular epidemiological data for P. malariae and P. brasilianum from Brazil obtained from different hosts and uses them to explore the genetic diversity in relation to geographical origin and hosts. By using microsatellite genotyping, we discovered that of the 14 human samples obtained from areas of the Atlantic forest, 5 different multilocus genotypes were recorded, while in a sample from an infected mosquito from the same region a different haplotype was found. We also analyzed the longitudinal change of circulating plasmodial genetic profile in two untreated non-symptomatic patients during a 12-months interval. The circulating genotypes in the two samples from the same patient presented nearly identical multilocus haplotypes (differing by a single locus). The more frequent haplotype persisted for almost 3 years in the human population. The allele Pm09-299 described previously as a genetic marker for South American P. malariae was not found in our samples. Of the 3 non-human primate samples from the Amazon Region, 3 different multilocus genotypes were recorded indicating a greater diversity among isolates of P. brasilianum compared to P. malariae and thus, P. malariae might in fact derive from P. brasilianum as has been proposed in recent studies. Taken together, our data show that based on the microsatellite data there is a relatively restricted polymorphism of P. malariae parasites as opposed to other geographic locations.
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Affiliation(s)
- L O Guimarães
- Núcleo de Estudos em Malária, Superintendência de Controle de Endemias/Instituto de Medicina Tropical de São Paulo, Universidade de São Paulo, Brazil
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Brito CFAD, Ferreira MU. Molecular markers and genetic diversity of Plasmodium vivax. Mem Inst Oswaldo Cruz 2012; 106 Suppl 1:12-26. [PMID: 21881753 DOI: 10.1590/s0074-02762011000900003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Accepted: 06/08/2011] [Indexed: 11/22/2022] Open
Abstract
Enhanced understanding of the transmission dynamics and population genetics for Plasmodium vivax is crucial in predicting the emergence and spread of novel parasite phenotypes with major public health implications, such as new relapsing patterns, drug resistance and increased virulence. Suitable molecular markers are required for these population genetic studies. Here, we focus on two groups of molecular markers that are commonly used to analyse natural populations of P. vivax. We use markers under selective pressure, for instance, antigen-coding polymorphic genes, and markers that are not under strong natural selection, such as most minisatellite and microsatellite loci. First, we review data obtained using genes encoding for P. vivax antigens: circumsporozoite protein, merozoite surface proteins 1 and 3α, apical membrane antigen 1 and Duffy binding antigen. We next address neutral or nearly neutral molecular markers, especially microsatellite loci, providing a complete list of markers that have already been used in P. vivax populations studies. We also analyse the microsatellite loci identified in the P. vivax genome project. Finally, we discuss some practical uses for P. vivax genotyping, for example, detecting multiple-clone infections and tracking the geographic origin of isolates.
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Arnott A, Barry AE, Reeder JC. Understanding the population genetics of Plasmodium vivax is essential for malaria control and elimination. Malar J 2012; 11:14. [PMID: 22233585 PMCID: PMC3298510 DOI: 10.1186/1475-2875-11-14] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Accepted: 01/10/2012] [Indexed: 11/22/2022] Open
Abstract
Traditionally, infection with Plasmodium vivax was thought to be benign and self-limiting, however, recent evidence has demonstrated that infection with P. vivax can also result in severe illness and death. Research into P. vivax has been relatively neglected and much remains unknown regarding the biology, pathogenesis and epidemiology of this parasite. One of the fundamental factors governing transmission and immunity is parasite diversity. An understanding of parasite population genetic structure is necessary to understand the epidemiology, diversity, distribution and dynamics of natural P. vivax populations. In addition, studying the population structure of genes under immune selection also enables investigation of the dynamic interplay between transmission and immunity, which is crucial for vaccine development. A lack of knowledge regarding the transmission and spread of P. vivax has been particularly highlighted in areas where malaria control and elimination programmes have made progress in reducing the burden of Plasmodium falciparum, yet P. vivax remains as a substantial obstacle. With malaria elimination back on the global agenda, mapping of global and local P. vivax population structure is essential prior to establishing goals for elimination and the roll-out of interventions. A detailed knowledge of the spatial distribution, transmission and clinical burden of P. vivax is required to act as a benchmark against which control targets can be set and measured. This paper presents an overview of what is known and what is yet to be fully understood regarding P. vivax population genetics, as well as the importance and application of P. vivax population genetics studies.
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Affiliation(s)
- Alicia Arnott
- Centre for Population Health, Burnet Institute, Melbourne, Australia
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Koepfli C, Ross A, Kiniboro B, Smith TA, Zimmerman PA, Siba P, Mueller I, Felger I. Multiplicity and diversity of Plasmodium vivax infections in a highly endemic region in Papua New Guinea. PLoS Negl Trop Dis 2011; 5:e1424. [PMID: 22206027 PMCID: PMC3243695 DOI: 10.1371/journal.pntd.0001424] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 10/21/2011] [Indexed: 11/19/2022] Open
Abstract
Plasmodium vivax is highly endemic in the lowlands of Papua New Guinea and accounts for a large proportion of the malaria cases in children less than 5 years of age. We collected 2117 blood samples at 2-monthly intervals from a cohort of 268 children aged 1 to 4.5 years and estimated the diversity and multiplicity of P. vivax infection. All P. vivax clones were genotyped using the merozoite surface protein 1 F3 fragment (msp1F3) and the microsatellite MS16 as molecular markers. High diversity was observed with msp1F3 (HE = 88.1%) and MS16 (HE = 97.8%). Of the 1162 P. vivax positive samples, 74% harbored multi-clone infections with a mean multiplicity of 2.7 (IQR = 1–3). The multiplicity of P. vivax infection increased slightly with age (P = 0.02), with the strongest increase in very young children. Intensified efforts to control malaria can benefit from knowledge of the diversity and MOI both for assessing the endemic situation and monitoring the effects of interventions. The parasite Plasmodium vivax is the second most frequent cause of malaria in humans. In the Maprik area in lowland Papua New Guinea, P. vivax and P. falciparum are sympatric each with a prevalence of around 50%. Longitudinal samples from 268 children aged 1 to 4.5 years over 16 months were collected. The 1162 blood samples positive for P. vivax were genotyped for two size-polymorphic molecular markers. A very high parasite diversity was observed. The number of co-infecting parasite clones per carrier (multiplicity) was nearly twice as high for P. vivax as for P. falciparum despite the similar prevalences of the species. The P. vivax multiplicity increased with age, with the strongest increase in young children below 1.5. This is likely to be a consequence of fast acquisition of immunity against P. vivax malaria and also of relapses, the release of long-lasting, silent liver stages to the blood stream. This is the first dataset from a highly endemic setting that presents data on a large number of individual P. vivax clones genotyped with highly diverse markers.
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Affiliation(s)
- Cristian Koepfli
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Amanda Ross
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | | | - Thomas A. Smith
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Peter A. Zimmerman
- Centre for Global Health and Disease, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Peter Siba
- PNG Institute of Medical Research, Goroka, Papua New Guinea
| | - Ivo Mueller
- PNG Institute of Medical Research, Goroka, Papua New Guinea
- Walter and Eliza Hall Institute, Parkville, Victoria, Australia
- Barcelona Centre for International Health Research, Barcelona, Spain
| | - Ingrid Felger
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- * E-mail:
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Honma H, Kim JY, Palacpac NMQ, Mita T, Lee W, Horii T, Tanabe K. Recent increase of genetic diversity in Plasmodium vivax population in the Republic of Korea. Malar J 2011; 10:257. [PMID: 21899730 PMCID: PMC3176257 DOI: 10.1186/1475-2875-10-257] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Accepted: 09/07/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The reemergence of Plasmodium vivax in South Korea since 1993 represents a serious public health concern. Despite the importance in understanding genetic diversity for control strategies, however, studies remain inconclusive with the general premise that due to low rate of malaria transmission, there is generally low genetic diversity with very few strains involved. In this study, the genetic diversity and population structure of P. vivax in South Korea were explored by analysing microsatellite polymorphism. METHODS Sequences for 13 microsatellite loci distributed across the twelve chromosomes of P. vivax were obtained from 58 South Korean isolates collected during two sampling periods, namely 1997-2000 and 2007. The sequences were used for the analysis of expected heterozygosity and multilocus genotype diversity. Population structure was evaluated using STRUCTURE version 2.3.2. Linkage disequilibrium was also analysed to investigate the extent of outbreeding in the P. vivax population. RESULTS Mean expected heterozygosity significantly increased from 0.382 in 1997-2000 to 0.545 in 2007 (P < 0.05). The number of multilocus genotypes was 7 and 27; and genotype diversity was statistically significant (P < 0.01) at 0.661 and 0.995 in 1997-2000 and 2007, respectively. Analysis by STRUCTURE showed a more complex population structure in 2007 than in 1997-2000. Linkage disequilibrium between 13 microsatellites, although significant in both time points, was notably lower in 2007. CONCLUSIONS The present microsatellite analysis clearly showed recent increase of genetic diversity and recent relaxation of the strong population structure observed in 1997-2000. These results suggest that multiple genotypes not present previously recently migrated into South Korea, accompanied by substantial outbreeding between different genotypes.
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Affiliation(s)
- Hajime Honma
- Department of Molecular Protozoology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
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Van den Eede P, Soto-Calle VE, Delgado C, Gamboa D, Grande T, Rodriguez H, Llanos-Cuentas A, Anné J, D'Alessandro U, Erhart A. Plasmodium vivax sub-patent infections after radical treatment are common in Peruvian patients: results of a 1-year prospective cohort study. PLoS One 2011; 6:e16257. [PMID: 21297986 PMCID: PMC3030575 DOI: 10.1371/journal.pone.0016257] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Accepted: 12/20/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND There is an increasing body of literature reporting treatment failure of the currently recommended radical treatment of Plasmodium vivax infections. As P. vivax is the main malaria species outside the African continent, emerging tolerance to its radical treatment regime could have major consequences in countries like Peru, where 80% of malaria cases are due to P. vivax. Here we describe the results of a 1-year longitudinal follow up of 51 confirmed P. vivax patients living around Iquitos, Peruvian Amazon, and treated according to the Peruvian national guidelines. METHODOLOGY Each month a blood sample for microscopy and later genotyping was systematically collected. Recent exposure to infection was estimated by detecting antibodies against the P. vivax circumsporozoite protein (CSP) and all PCR confirmed P. vivax infections were genotyped with 16 polymorphic microsatellites. RESULTS During a 1-year period, 84 recurrent infections, 22 positive also by microscopy, were identified, with a median survival time to first recurrent infection of 203 days. Most of them (71%) were asymptomatic; in 13 patients the infection persisted undetected by microscopy for several consecutive months. The genotype of mostly recurrent infections differed from that at day 0 while fewer differences were seen between the recurrent infections. The average expected heterozygosity was 0.56. There was strong linkage disequilibrium (I(A)(s) = 0.29, p<1.10(-4)) that remained also when analyzing only the unique haplotypes, suggesting common inbreeding. CONCLUSION In Peru, the P. vivax recurrent infections were common and displayed a high turnover of parasite genotypes compared to day 0. Plasmodium vivax patients, even when treated according to the national guidelines, may still represent an important parasite reservoir that can maintain transmission. Any elimination effort should consider such a hidden reservoir.
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Affiliation(s)
- Peter Van den Eede
- Department of Parasitology, Institute of Tropical Medicine, Antwerp, Belgium.
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Zeyrek FY, Tachibana SI, Yuksel F, Doni N, Palacpac N, Arisue N, Horii T, Coban C, Tanabe K. Limited polymorphism of the Plasmodium vivax merozoite surface protein 1 gene in isolates from Turkey. Am J Trop Med Hyg 2011; 83:1230-7. [PMID: 21118926 DOI: 10.4269/ajtmh.2010.10-0353] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The 200-kD merozoite surface protein of Plasmodium vivax (PvMSP-1) is one of the leading vaccine candidates against P. vivax malaria. However, the gene encoding PvMSP-1 (pvmsp1) is highly polymorphic and is a major obstacle to effective vaccine development. To further understand polymorphism in pvmsp1, we obtained 30 full-length pvmsp1 sequences from southeastern Turkey. Comparative analysis of sequences from Turkey and other areas showed substantially limited polymorphism. Substitutions were found at 280 and 162 amino acid sites in samples from other regions and those from Turkey, respectively. Eight substitutions were unique to Turkey. In one of them, D/E at position 1706 in the C-terminal 19-kD region, the K/E change at 1709 was the only polymorphism previously known. Limited diversity was also observed in microsatellites. Data suggest a recent population bottleneck in Turkey that may have obscured a signature for balancing selection in the C-terminal 42-kD region, which was otherwise detectable in other areas.
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Affiliation(s)
- Fadile Yildiz Zeyrek
- Department of Microbiology, Harran University Medical Faculty, Sanliurfa, Turkey.
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Whole-genome sequencing and microarray analysis of ex vivo Plasmodium vivax reveal selective pressure on putative drug resistance genes. Proc Natl Acad Sci U S A 2010; 107:20045-50. [PMID: 21037109 DOI: 10.1073/pnas.1003776107] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Plasmodium vivax causes 25-40% of malaria cases worldwide, yet research on this human malaria parasite has been neglected. Nevertheless, the recent publication of the P. vivax reference genome now allows genomics and systems biology approaches to be applied to this pathogen. We show here that whole-genome analysis of the parasite can be achieved directly from ex vivo-isolated parasites, without the need for in vitro propagation. A single isolate of P. vivax obtained from a febrile patient with clinical malaria from Peru was subjected to whole-genome sequencing (30× coverage). This analysis revealed over 18,261 single-nucleotide polymorphisms (SNPs), 6,257 of which were further validated using a tiling microarray. Within core chromosomal genes we find that one SNP per every 985 bases of coding sequence distinguishes this recent Peruvian isolate, designated IQ07, from the reference Salvador I strain obtained in 1972. This full-genome sequence of an uncultured P. vivax isolate shows that the same regions with low numbers of aligned sequencing reads are also highly variable by genomic microarray analysis. Finally, we show that the genes containing the largest ratio of nonsynonymous-to-synonymous SNPs include two AP2 transcription factors and the P. vivax multidrug resistance-associated protein (PvMRP1), an ABC transporter shown to be associated with quinoline and antifolate tolerance in Plasmodium falciparum. This analysis provides a data set for comparative analysis with important potential for identifying markers for global parasite diversity and drug resistance mapping studies.
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Van den Eede P, Van der Auwera G, Delgado C, Huyse T, Soto-Calle VE, Gamboa D, Grande T, Rodriguez H, Llanos A, Anné J, Erhart A, D'Alessandro U. Multilocus genotyping reveals high heterogeneity and strong local population structure of the Plasmodium vivax population in the Peruvian Amazon. Malar J 2010; 9:151. [PMID: 20525233 PMCID: PMC2898784 DOI: 10.1186/1475-2875-9-151] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Accepted: 06/03/2010] [Indexed: 11/22/2022] Open
Abstract
Background Peru is one of the Latin American countries with the highest malaria burden, mainly due to Plasmodium vivax infections. However, little is known about P. vivax transmission dynamics in the Peruvian Amazon, where most malaria cases occur. The genetic diversity and population structure of P. vivax isolates collected in different communities around Iquitos city, the capital of the Peruvian Amazon, was determined. Methods Plasmodium vivax population structure was determined by multilocus genotyping with 16 microsatellites on 159 P. vivax infected blood samples (mono-infections) collected in four sites around Iquitos city. The population characteristics were assessed only in samples with monoclonal infections (n = 94), and the genetic diversity was determined by calculating the expected heterozygosity and allelic richness. Both linkage disequilibrium and the genetic differentiation (θ) were estimated. Results The proportion of polyclonal infections varied substantially by site (11% - 70%), with the expected heterozygosity ranging between 0.44 and 0.69; no haplotypes were shared between the different populations. Linkage disequilibrium was present in all populations (IAS 0.14 - 0.61) but was higher in those with fewer polyclonal infections, suggesting inbreeding and a clonal population structure. Strong population differentiation (θ = 0.45) was found and the Bayesian inference cluster analysis identified six clusters based on distinctive allele frequencies. Conclusion The P. vivax populations circulating in the Peruvian Amazon basin are genetically diverse, strongly differentiated and they have a low effective recombination rate. These results are in line with the low and clustered pattern of malaria transmission observed in the region around Iquitos city.
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Affiliation(s)
- Peter Van den Eede
- Department of Parasitology, Institute of Tropical Medicine, Antwerp, Belgium.
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