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Huijben S, Macete E, Mombo-Ngoma G, Ramharter M, Kariuki S, Desai M, Shi YP, Mwangoka G, Massougbodji A, Cot M, Ndam NT, Uberegui E, Gupta H, Cisteró P, Aponte JJ, González R, Menéndez C, Mayor A. Counter-Selection of Antimalarial Resistance Polymorphisms by Intermittent Preventive Treatment in Pregnancy. J Infect Dis 2020; 221:293-303. [PMID: 31677349 DOI: 10.1093/infdis/jiz451] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 09/19/2019] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Innovative approaches are needed to limit antimalarial resistance evolution. Understanding the role of intermittent preventive treatment in pregnancy (IPTp) on the selection for resistance and the impact such selection has on pregnancy outcomes can guide future interventions. METHODS Plasmodium falciparum isolates (n = 914) from 2 randomized clinical trials were screened for pfmdr1 copy number variation and pfcrt, pfmdr1, pfdhfr, and pfdhps resistance markers. The trials were conducted between 2010 and 2013 in Benin, Gabon, Kenya, and Mozambique to establish the efficacy of IPTp-mefloquine (MQ) compared with IPTp-sulphadoxine-pyrimethamine (SP) in human immunodeficiency virus (HIV)-uninfected and to IPTp-placebo in HIV-infected women. RESULTS In HIV-uninfected women, the prevalence of pfcrt mutants, pfdhfr/pfdhps quintuple mutants, and pfmdr1 copy number was similar between women receiving IPT-SP and IPTp-MQ. However, prevalence of pfmdr1 polymorphism 86Y was lower in the IPTp-MQ group than in the IPTp-SP group, and within the IPTp-MQ group it was lower at delivery compared with recruitment. No effect of IPTp-MQ on resistance markers was observed among HIV-infected women. The carriage of resistance markers was not associated with pregnancy outcomes. CONCLUSIONS Selection of wild-type pfmdr1 polymorphism N86 by IPTp-MQ highlights the strong selective pressure IPTp can exert and the opportunity for using negative cross-resistance in drug choice for clinical treatment and IPTp.
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Affiliation(s)
- Silvie Huijben
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.,Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Eusebio Macete
- Centro de Investigação em Saúde da Manhiça, Manhiça, Mozambique
| | - Ghyslain Mombo-Ngoma
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon.,Institut für Tropenmedizin, Universität Tübingen, und Deutsches Zentrum für Infektionsforschung, Tübingen, Germany.,Department of Tropical Medicine, Bernhard Nocht Institute for Tropical Medicine and Department of Medicine I, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Michael Ramharter
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon.,Department of Tropical Medicine, Bernhard Nocht Institute for Tropical Medicine and Department of Medicine I, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Simon Kariuki
- Kenya Medical Research Institute/Centre for Global Health Research, Kisumu, Kenya
| | - Meghna Desai
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Ya Ping Shi
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | | | - Achille Massougbodji
- Unité d'Enseignement et de Recherche de Parasitologie Mycologie, Faculté des Sciences de la Santé, Cotonou, Bénin
| | - Michel Cot
- Université de Paris, MERIT, IRD, Paris, France
| | | | | | - Himanshu Gupta
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
| | - Pau Cisteró
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
| | - John J Aponte
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.,Centro de Investigação em Saúde da Manhiça, Manhiça, Mozambique
| | - Raquel González
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.,Centro de Investigação em Saúde da Manhiça, Manhiça, Mozambique
| | - Clara Menéndez
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.,Centro de Investigação em Saúde da Manhiça, Manhiça, Mozambique
| | - Alfredo Mayor
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.,Centro de Investigação em Saúde da Manhiça, Manhiça, Mozambique
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Tyagi RK, Gleeson PJ, Arnold L, Tahar R, Prieur E, Decosterd L, Pérignon JL, Olliaro P, Druilhe P. High-level artemisinin-resistance with quinine co-resistance emerges in P. falciparum malaria under in vivo artesunate pressure. BMC Med 2018; 16:181. [PMID: 30269689 PMCID: PMC6166299 DOI: 10.1186/s12916-018-1156-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 08/17/2018] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Humanity has become largely dependent on artemisinin derivatives for both the treatment and control of malaria, with few alternatives available. A Plasmodium falciparum phenotype with delayed parasite clearance during artemisinin-based combination therapy has established in Southeast Asia, and is emerging elsewhere. Therefore, we must know how fast, and by how much, artemisinin-resistance can strengthen. METHODS P. falciparum was subjected to discontinuous in vivo artemisinin drug pressure by capitalizing on a novel model that allows for long-lasting, high-parasite loads. Intravenous artesunate was administered, using either single flash-doses or a 2-day regimen, to P. falciparum-infected humanized NOD/SCID IL-2Rγ-/-immunocompromised mice, with progressive dose increments as parasites recovered. The parasite's response to artemisinins and other available anti-malarial compounds was characterized in vivo and in vitro. RESULTS Artemisinin resistance evolved very rapidly up to extreme, near-lethal doses of artesunate (240 mg/kg), an increase of > 3000-fold in the effective in vivo dose, far above resistance levels reported from the field. Artemisinin resistance selection was reproducible, occurring in 80% and 41% of mice treated with flash-dose and 2-day regimens, respectively, and the resistance phenotype was stable. Measuring in vitro sensitivity proved inappropriate as an early marker of resistance, as IC50 remained stable despite in vivo resistance up to 30 mg/kg (ART-S: 10.7 nM (95% CI 10.2-11.2) vs. ART-R30: 11.5 nM (6.6-16.9), F = 0.525, p = 0.47). However, when in vivo resistance strengthened further, IC50 increased 10-fold (ART-R240 100.3 nM (92.9-118.4), F = 304.8, p < 0.0001), reaching a level much higher than ever seen in clinical samples. Artemisinin resistance in this African P. falciparum strain was not associated with mutations in kelch-13, casting doubt over the universality of this genetic marker for resistance screening. Remarkably, despite exclusive exposure to artesunate, full resistance to quinine, the only other drug sufficiently fast-acting to deal with severe malaria, evolved independently in two parasite lines exposed to different artesunate regimens in vivo, and was confirmed in vitro. CONCLUSION P. falciparum has the potential to evolve extreme artemisinin resistance and more complex patterns of multidrug resistance than anticipated. If resistance in the field continues to advance along this trajectory, we will be left with a limited choice of suboptimal treatments for acute malaria, and no satisfactory option for severe malaria.
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Affiliation(s)
- Rajeev K Tyagi
- The Vac4All Initiative, 26 Rue Lecourbe, 75015, Paris, France
- Biomedical Parasitology Unit, Institut Pasteur, Paris, France
- Present Address: Amity Institute of Microbial Technology, Amity University, Noida, Uttar Pradesh, India
| | - Patrick J Gleeson
- The Vac4All Initiative, 26 Rue Lecourbe, 75015, Paris, France
- Biomedical Parasitology Unit, Institut Pasteur, Paris, France
- Present Address: Centre de Recherche sur l'Inflammation, INSERM U1149, Faculté de Médecine, Université Diderot-Site Bichat, 16 rue Henri Huchard, 75018, Paris, France
| | - Ludovic Arnold
- The Vac4All Initiative, 26 Rue Lecourbe, 75015, Paris, France
- Biomedical Parasitology Unit, Institut Pasteur, Paris, France
| | - Rachida Tahar
- Faculté de Pharmacie, Université Paris Descartes, COMUE Sorbonne Paris Cité, Paris, France
- Institut de Recherche pour le Développement, UMR MERIT 216, Paris, France
| | - Eric Prieur
- The Vac4All Initiative, 26 Rue Lecourbe, 75015, Paris, France
- Biomedical Parasitology Unit, Institut Pasteur, Paris, France
| | - Laurent Decosterd
- Division of Clinical Pharmacology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Jean-Louis Pérignon
- The Vac4All Initiative, 26 Rue Lecourbe, 75015, Paris, France
- Biomedical Parasitology Unit, Institut Pasteur, Paris, France
- Present Address: Laboratoire de Biochimie, Hôpital Necker-Enfants Malades, Paris, France
| | - Piero Olliaro
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Pierre Druilhe
- The Vac4All Initiative, 26 Rue Lecourbe, 75015, Paris, France.
- Biomedical Parasitology Unit, Institut Pasteur, Paris, France.
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A Review of Pharmacogenetics of Antimalarials and Associated Clinical Implications. Eur J Drug Metab Pharmacokinet 2018; 42:745-756. [PMID: 28070879 DOI: 10.1007/s13318-016-0399-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Genetic variability in drug-metabolizing enzymes and drug transporters is known to influence the pharmacokinetics of many drugs. Antimalarial drugs are a class of agents known to utilize metabolic and elimination pathways prone to genetic variation. This paper aims to review the genetic variants affecting antimalarial medications and discuss their clinical implications. Data were identified for the genes coding for the cytochrome P450 (CYP) enzymes: CYP2C8, CYP2C19, CYP2A6, CYP2D6, CYP2B6, and the P-glycoprotein drug transporter. Adverse effects of amodiaquine were more common in patients with decreased CYP2C8 metabolism. CYP2C19 variants influenced the metabolism of proguanil but no differences in efficacy outcomes were observed. Ultra-metabolizers of CYP2A6 showed increased incidence of adverse effects of artesunate (prodrug for active metabolite, dihydroartemisinin). In the presence of efavirenz, mutations in CYP2B6 influenced the number of patients achieving day-7 lumefantrine concentrations above accepted therapeutic cut-offs. Lumefantrine concentrations were also influenced by ABCB1 variants in the presence of nevirapine. The most critical pharmacogenetic consideration identified was the association of glucose-6-phosphate dehydrogenase deficiency with development of hemolytic anemia and decreased hemoglobin levels in patients treated with primaquine or a combination of chlorproguanil-dapsone-artesunate. These findings demonstrate a need for close monitoring of patients originating from populations where genetic variation in metabolizing enzymes is prevalent, so as to ensure that optimal clinical outcomes are achieved. Future studies should determine which populations are at greatest risk of potential treatment failures and/or adverse effects, which drugs are most susceptible to genetic variation in metabolizing enzymes, and the impact of genetic influence on the efficacy and safety of first-line treatment regimens.
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Runtuwene LR, Tuda JSB, Mongan AE, Makalowski W, Frith MC, Imwong M, Srisutham S, Nguyen Thi LA, Tuan NN, Eshita Y, Maeda R, Yamagishi J, Suzuki Y. Nanopore sequencing of drug-resistance-associated genes in malaria parasites, Plasmodium falciparum. Sci Rep 2018; 8:8286. [PMID: 29844487 PMCID: PMC5974085 DOI: 10.1038/s41598-018-26334-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 05/10/2018] [Indexed: 11/09/2022] Open
Abstract
Here, we report the application of a portable sequencer, MinION, for genotyping the malaria parasite Plasmodium falciparum. In the present study, an amplicon mixture of nine representative genes causing resistance to anti-malaria drugs is diagnosed. First, we developed the procedure for four laboratory strains (3D7, Dd2, 7G8, and K1), and then applied the developed procedure to ten clinical samples. We sequenced and re-sequenced the samples using the obsolete flow cell R7.3 and the most recent flow cell R9.4. Although the average base-call accuracy of the MinION sequencer was 74.3%, performing >50 reads at a given position improves the accuracy of the SNP call, yielding a precision and recall rate of 0.92 and 0.8, respectively, with flow cell R7.3. These numbers increased significantly with flow cell R9.4, in which the precision and recall are 1 and 0.97, respectively. Based on the SNP information, the drug resistance status in ten clinical samples was inferred. We also analyzed K13 gene mutations from 54 additional clinical samples as a proof of concept. We found that a novel amino-acid changing variation is dominant in this area. In addition, we performed a small population-based analysis using 3 and 5 cases (K13) and 10 and 5 cases (PfCRT) from Thailand and Vietnam, respectively. We identified distinct genotypes from the respective regions. This approach will change the standard methodology for the sequencing diagnosis of malaria parasites, especially in developing countries.
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Affiliation(s)
- Lucky R Runtuwene
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8562, Japan
| | - Josef S B Tuda
- Faculty of Medicine, Sam Ratulangi University, Kampus Unsrat, Bahu Manado, 95115, Indonesia
| | - Arthur E Mongan
- Faculty of Medicine, Sam Ratulangi University, Kampus Unsrat, Bahu Manado, 95115, Indonesia
| | - Wojciech Makalowski
- Institute of Bioinformatics, Faculty of Medicine, University of Münster, Niels-Stensen Strasse 14, Münster, 48149, Germany
| | - Martin C Frith
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8562, Japan.,Artificial Intelligence Research Center, Advanced Industrial Science and Technology, 2-3-26, Aomi, Koto-ku, Tokyo, 135-0064, Japan.,AIST-Waseda CBBD-OIL, 3-4-1 Ookubo, Shinjuku-ku, Tokyo, 169-8555, Japan
| | - Mallika Imwong
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Thung Phaya Thai, Ratchathewi, Bangkok, 10400, Thailand
| | - Suttipat Srisutham
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Thung Phaya Thai, Ratchathewi, Bangkok, 10400, Thailand
| | - Lan Anh Nguyen Thi
- National Institute of Hygiene and Epidemiology, 1 Yersin Street, Hanoi, 112800, Vietnam
| | - Nghia Nguyen Tuan
- National Institute of Hygiene and Epidemiology, 1 Yersin Street, Hanoi, 112800, Vietnam
| | - Yuki Eshita
- Division of Collaboration and Education, Research Center for Zoonosis Control, Hokkaido University, North 20, West 10 Kita-ku, Sapporo, Hokkaido, 001-0020, Japan.,Department of Medical Entomology, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Thung Phaya Thai, Ratchathewi, Bangkok, 10400, Thailand
| | - Ryuichiro Maeda
- Division of Biomedical Science, Department of Basic Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Nishi 2 Sen-11 Inadacho, Obihiro, Hokkaido, 080-0834, Japan
| | - Junya Yamagishi
- Global Station for Zoonosis Control, GI-CoRE, Hokkaido University, North 20, West 10 Kita-ku, Sapporo, Hokkaido, 001-0020, Japan
| | - Yutaka Suzuki
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8562, Japan.
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Sharma S, Bharti RS, Bhardwaj N, Anvikar AR, Valecha N, Mishra N. Correlation of in vitro Sensitivity of Chloroquine and other Antimalarials with the Partner Drug Resistance to Plasmodium falciparum Malaria in Selected Sites of India. Indian J Med Microbiol 2017; 35:485-490. [DOI: 10.4103/ijmm.ijmm_17_160] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Koukouikila-Koussounda F, Jeyaraj S, Nguetse CN, Nkonganyi CN, Kokou KC, Etoka-Beka MK, Ntoumi F, Velavan TP. Molecular surveillance of Plasmodium falciparum drug resistance in the Republic of Congo: four and nine years after the introduction of artemisinin-based combination therapy. Malar J 2017; 16:155. [PMID: 28420403 PMCID: PMC5395861 DOI: 10.1186/s12936-017-1816-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 04/09/2017] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Resistance to anti-malarial drugs hinders efforts on malaria elimination and eradication. Following the global spread of chloroquine-resistant parasites, the Republic of Congo adopted artemisinin-based combination therapy (ACT) in 2006 as a first-line treatment for uncomplicated malaria. To assess the impacts after implementation of ACT, a molecular surveillance for anti-malarial drug resistance was conducted in Congo 4 and 9 years after the introduction of ACT. METHODS Blood samples of 431 febrile children aged 1-10 years were utilized from two previous studies conducted in 2010 (N = 311) and 2015 (N = 120). All samples were screened for malaria parasites using nested PCR. Direct sequencing was used to determine the frequency distribution of genetic variants in the anti-malarial drug-resistant Plasmodium falciparum genes (Pfcrt, Pfmdr1, Pfatp6, Pfk13) in malaria-positive isolates. RESULTS One-hundred and nineteen (N = 70 from 2010 and N = 49 from 2015) samples were positive for P. falciparum. A relative decrease in the proportion of chloroquine-resistant haplotype (CVIET) from 100% in 2005, 1 year before the introduction and implementation of ACT in 2006, to 98% in 2010 to 71% in 2015 was observed. Regarding the multidrug transporter gene, a considerable reduction in the frequency of the mutations N86Y (from 73 to 27%) and D1246Y (from 22 to 0%) was observed. However, the prevalence of the Y184F mutation remained stable (49% in 2010 compared to 54% in 2015). Isolates carrying the Pfatp6 H243Y was 25% in 2010 and this frequency was reduced to null in 2015. None of the parasites harboured the Pfk13 mutations associated with prolonged artemisinin clearance in Southeast Asia. Nevertheless, 13 new Pfk13 variants are reported among the investigated isolates. CONCLUSION The implementation of ACT has led to the decline in prevalence of chloroquine-resistant parasites in the Republic of Congo. However, the constant prevalence of the PfMDR1 Y184F mutation, associated with lumefantrine susceptibility, indicate a selective drug pressure still exists. Taken together, this study could serve as the basis for epidemiological studies monitoring the distribution of molecular markers of artemisinin resistance in the Republic of Congo.
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Affiliation(s)
| | | | | | | | | | | | - Francine Ntoumi
- Fondation Congolaise pour la Recherche Médicale (FCRM), Brazzaville, Republic of Congo.,Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | - Thirumalaisamy P Velavan
- Fondation Congolaise pour la Recherche Médicale (FCRM), Brazzaville, Republic of Congo. .,Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany. .,Duy Tan University, Da Nang, Vietnam. .,Vietnamese-German Centre for Medical Research, Hanoi, Vietnam.
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Gil JP, Krishna S. pfmdr1 (Plasmodium falciparum multidrug drug resistance gene 1): a pivotal factor in malaria resistance to artemisinin combination therapies. Expert Rev Anti Infect Ther 2017; 15:527-543. [DOI: 10.1080/14787210.2017.1313703] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- J. Pedro Gil
- Physiology and Pharmacology Department, Karolinska Institutet, Stockholm, Sweden
| | - S. Krishna
- St George’s University Hospital, Institute for Infection and Immunity, London, United Kingdom
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8
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Change in molecular weight due to important pfatp6 and pfmdr1 polymorphisms and susceptibility to antimalarial drug: Possible role of epigenetic phenomenon. Asian Pac J Trop Biomed 2017. [DOI: 10.1016/j.apjtb.2016.12.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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9
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Reappraising the effects of artemisinin on the ATPase activity of PfATP6 and SERCA1a E255L expressed in Xenopus laevis oocytes. Nat Struct Mol Biol 2016; 23:1-2. [PMID: 26733217 DOI: 10.1038/nsmb.3156] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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10
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Lo E, Nguyen J, Oo W, Hemming-Schroeder E, Zhou G, Yang Z, Cui L, Yan G. Examining Plasmodium falciparum and P. vivax clearance subsequent to antimalarial drug treatment in the Myanmar-China border area based on quantitative real-time polymerase chain reaction. BMC Infect Dis 2016; 16:154. [PMID: 27084511 PMCID: PMC4833920 DOI: 10.1186/s12879-016-1482-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 03/25/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Recent emergence of artemisinin-resistant P. falciparum has posed a serious hindrance to the elimination of malaria in the Greater Mekong Subregion. Parasite clearance time, a measure of change in peripheral parasitaemia in a sequence of samples taken after treatment, can be used to reflect the susceptibility of parasites or the efficiency of antimalarials. The association of genetic polymorphisms and artemisinin resistance has been documented. This study aims to examine clearance time of P. falciparum and P. vivax parasitemia as well as putative gene mutations associated with residual or recurred parasitemia in Myanmar. METHODS A total of 63 P. falciparum and 130 P. vivax samples collected from two internally-displaced populations and one surrounding village were examined for parasitemia changes. At least four samples were taken from each patient, at the first day of diagnosis up to 3 months following the initial treatment. The amount of parasite gene copy number was estimated using quantitative real-time PCR based on a species-specific region of the 18S rRNA gene. For samples that showed residual or recurred parasitemia after treatment, microsatellites were used to identify the 'post-treatment' parasite genotype and compared such with the 'pre-treatment' genotype. Mutations in genes pfcrt, pfmdr1, pfatp6, pfmrp1 and pfK13 that are potentially associated with ACT resistance were examined to identify if mutation is a factor for residual or persistent parasitemia. RESULTS Over 30% of the P. falciprium infections showed delayed clearance of parasitemia after 2-3 days of treatment and 9.5% showed recurred parasitemia. Mutations in codon 876 of the pfmrp1 corroborated significance association with slow clearance time. However, no association was observed in the variation in pfmdr1 gene copy number as well as mutations of various codonsinpfatp6, pfcrt, and pfK13 with clearance time. For P. vivax, over 95% of the infections indicated cleared parasitemia at days 2-3 of treatment. Four samples were found to be re-infected with new parasite strains based on microsatellite genotypes after initial treatment. CONCLUSION The appearance of P.falciparum infected samples showing delayed clearance or recurred parasitemia after treatment raises concerns on current treatment and ACT drug resistance.
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Affiliation(s)
- Eugenia Lo
- />Program in Public Health, University of California at Irvine, Irvine, CA 92697-4050 USA
| | - Jennifer Nguyen
- />Program in Public Health, University of California at Irvine, Irvine, CA 92697-4050 USA
| | - Winny Oo
- />Program in Public Health, University of California at Irvine, Irvine, CA 92697-4050 USA
| | | | - Guofa Zhou
- />Program in Public Health, University of California at Irvine, Irvine, CA 92697-4050 USA
| | - Zhaoqing Yang
- />Department of Pathogen Biology and Immunology, Kunming Medical University, Kunming, China
| | - Liwang Cui
- />Department of Entomology, Pennsylvania State University, University Park, PA USA
| | - Guiyun Yan
- />Program in Public Health, University of California at Irvine, Irvine, CA 92697-4050 USA
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11
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Gupta R, Mishra N, Kumar A, Rana R, Srivastava B, Tyagi PK, Anvikar AR, Valecha N. Monitoring artemisinin resistance in Plasmodium falciparum: comparison of parasite clearance time by microscopy and real-time PCR and evaluation of mutations in Pfatpase6 gene in Odisha state of India. Parasitol Res 2015; 114:3487-96. [DOI: 10.1007/s00436-015-4577-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 06/10/2015] [Indexed: 11/28/2022]
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12
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Nyunt MH, Hlaing T, Oo HW, Tin-Oo LLK, Phway HP, Wang B, Zaw NN, Han SS, Tun T, San KK, Kyaw MP, Han ET. Molecular assessment of artemisinin resistance markers, polymorphisms in the k13 propeller, and a multidrug-resistance gene in the eastern and western border areas of Myanmar. Clin Infect Dis 2014; 60:1208-15. [PMID: 25537878 DOI: 10.1093/cid/ciu1160] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND As K13 propeller mutations have been recently reported to serve as molecular markers, assessment of K13 propeller polymorphisms in multidrug-resistant gene in isolates from Myanmar, especially the eastern and western border areas, is crucial if we are to understand the spread of artemisinin resistance. METHODS A 3-day surveillance study was conducted in the eastern and western border areas in Myanmar, and K13 propeller and Plasmodium falciparum multidrug resistance-associated protein 1 (pfmrp1) mutations were analyzed. RESULTS Among the 1761 suspected malaria cases screened, a total of 42 uncomplicated falciparum cases from the eastern border and 49 from the western border were subjected to 3 days of surveillance after artemether-lumefantrine treatment. No parasitemic case showing positivity on day 3 was noted from the western border, but 26.2% (11/42) of cases were positive in the eastern border. Although we found no marked difference in the prevalence of the pfmrp1 mutation in the eastern and western borders (36% vs 31%, respectively), K13 mutations were more frequent in the eastern border area (where the 3-day persistent cases were detected; 48% vs 14%). C580Y, M476I, A481V, N458Y, R539T, and R516Y accounted for 68.9% of all K13 mutations significantly associated with day 3 parasitaemia. CONCLUSIONS The K13 mutations were significantly associated with day 3 parasitaemia, emphasizing the importance of K13 surveillance. The low prevalence of K13 mutations and the absence of day 3 parasitaemic cases indicate that artemisinin resistance may not have spread to the western Myanmar border region. Although analysis of multiple K13 mutations is challenging, it should be done at various sentinel sites in Myanmar.
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Affiliation(s)
- Myat Htut Nyunt
- Department of Medical Research (Lower Myanmar), Yangon, Republic of the Union of Myanmar Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Republic of Korea
| | - Thaung Hlaing
- Department of Health, Nay Pyi Taw, Republic of the Union of Myanmar
| | - Htet Wai Oo
- Department of Medical Research (Lower Myanmar), Yangon, Republic of the Union of Myanmar
| | - Lu-Lu Kyaw Tin-Oo
- Department of Medical Research (Lower Myanmar), Yangon, Republic of the Union of Myanmar
| | - Hnin Phyu Phway
- Department of Medical Research (Lower Myanmar), Yangon, Republic of the Union of Myanmar
| | - Bo Wang
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Republic of Korea
| | - Ni Ni Zaw
- Department of Medical Research (Lower Myanmar), Yangon, Republic of the Union of Myanmar
| | - Soe Soe Han
- Department of Medical Research (Lower Myanmar), Yangon, Republic of the Union of Myanmar
| | - Thurein Tun
- Department of Medical Research (Lower Myanmar), Yangon, Republic of the Union of Myanmar
| | - Kyaw Kyaw San
- Department of Medical Research (Lower Myanmar), Yangon, Republic of the Union of Myanmar
| | - Myat Phone Kyaw
- Department of Medical Research (Lower Myanmar), Yangon, Republic of the Union of Myanmar
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Republic of Korea
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Phompradit P, Muhamad P, Chaijaroenkul W, Na-Bangchang K. Genetic polymorphisms of candidate markers and in vitro susceptibility of Plasmodium falciparum isolates from Thai-Myanmar border in relation to clinical response to artesunate-mefloquine combination. Acta Trop 2014; 139:77-83. [PMID: 25004442 DOI: 10.1016/j.actatropica.2014.06.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 06/25/2014] [Accepted: 06/29/2014] [Indexed: 11/15/2022]
Abstract
The genetic polymorphisms of the candidate markers of antimalarial drug resistance pfcrt, pfmdr1, pfatp6, and pfmrp1 were investigated in relationship with in vitro susceptibility of Plasmodium falciparum isolates and clinical response following artesunate (AS)-mefloquine (MQ) combination in 21 and 27 samples obtained from patients with recrudescence and adequate clinical response, respectively. MQ (21.0 vs. 49.9nM) and AS (1.6 vs. 2.8nM) IC50 values (concentrations that inhibit parasite growth by 50%) were significantly higher in isolates collected from patients with recrudescence. Furthermore, a significantly higher MQ IC50 was found in isolates from patients with recrudescence that carried pfmrp1 mutations at amino acid residues 191Y, 437A, and 876V. For AS sensitivity, a significant association was also detected in isolates from patients with recrudescence that carried gene mutations at amino acid residues 437A and 876V. MQ IC50 of the isolates with recrudescence which carried ≥4 pfmdr1 gene copies was significantly higher than that carrying only one gene copy. In addition, a significantly higher proportion of isolates carrying one gene copy was detected in the group with adequate clinical response compared with recrudescence. Results from this limited sample size suggested the potential link between pfmdr1 gene copy number and pfmrp1 gene mutation, in vitro parasite susceptibility, and AS-MQ treatment response.
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Affiliation(s)
- Papichaya Phompradit
- Graduate program in Biomedical Sciences, Faculty of Allied Health Sciences, Thammasat University (Rangsit Campus), Patumthani 12121, Thailand
| | - Poonuch Muhamad
- Thailand center of Excellence on Drug Discovery and Development, Thammasat University (Rangsit campus), Patumthani 12121, Thailand
| | - Wanna Chaijaroenkul
- Chulabhorn International College of Medicine, Thammasat University (Rangsit Campus), Patumthani 12121, Thailand
| | - Kesara Na-Bangchang
- Chulabhorn International College of Medicine, Thammasat University (Rangsit Campus), Patumthani 12121, Thailand.
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Li J, Chen J, Xie D, Monte-Nguba SM, Eyi JUM, Matesa RA, Obono MMO, Ehapo CS, Yang L, Lu D, Yang H, Yang HT, Lin M. High prevalence of pfmdr1 N86Y and Y184F mutations in Plasmodium falciparum isolates from Bioko Island, Equatorial Guinea. Pathog Glob Health 2014; 108:339-43. [PMID: 25348116 DOI: 10.1179/2047773214y.0000000158] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
OBJECTIVE Drug resistance against Plasmodium falciparum has been recognized as the crucial obstacle to curbing mortality and morbidity from malaria. To investigate the distribution and pattern of multidrug resistance 1 (pfmdr1) gene polymorphisms in P. falciparum, isolates collected from the malaria high-endemic Bioko Island, Equatorial Guinea. METHODS Blood samples were collected from 217 patients with P. falciparum malaria during rainy season in 2012 on Bioko Island. These samples were extracted using Chelex to obtain parasite DNA. Nest-polymerase chain reaction (PCR) and sequencing were employed to detect mutations (N86Y, E130K, Y184F, S1034C, N1042D, V1109I, and D1246Y) and haplotypes in pfmdr1 gene. RESULTS A total of 151 samples were successfully detected for pfmdr1 mutations from the 217 patients. Pfmdr1 mutations were found in 91·39% (138/151) P. falciparum isolates. However, no mutation at 130 and 1109 was identified from these samples. Four haplotypes coding 86, 184, 1034, 1,042, and 1,246 were found including NYSND, YYSND, NFSND, and YFSND, which accounted for 8·61% (13/151), 2·65% (4/151), 29·80% (45/151), and 58·94% (89/151), respectively. CONCLUSIONS Our results exhibited hypersensitivity to lumefantrine (LU) and mefloquine (MQ) and resistance to chloroquine (CQ) and amodiaquine (AQ) in P. falciparum isolates from Bioko Island. This information will be useful for anti-malarial drug policy in Equatorial Guinea.
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Analysis of polymorphisms in Plasmodium falciparum genes related to drug resistance: a survey over four decades under different treatment policies in Brazil. Malar J 2014; 13:372. [PMID: 25239550 PMCID: PMC4177603 DOI: 10.1186/1475-2875-13-372] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 09/14/2014] [Indexed: 12/31/2022] Open
Abstract
Background Anti-malarial resistance in Plasmodium falciparum remains an obstacle for malaria control. Resistance-associated genes were analysed in Brazilian samples over four decades to evaluate the impact of different treatment regimens on the parasite genetic profile. Methods Samples were collected on filter paper from patients infected in the Amazon region from 1984 to 2011. DNA was extracted with Chelex® 100 and monoinfection confirmed by PCR. SNPs in the pfcrt, pfmdr1, pfdhfr and pfdhps genes were assessed by PCR-RFLP. The pfmdr1 copy number was estimated using real time quantitative PCR with SYBR® Green. Parasite response was assessed ex vivo with seven concentrations of each anti-malarial. Patients were treated according to Brazilian guidelines: quinine plus tetracycline or mefloquine in period 1 and ACT in period 2. Results All 96 samples presented the pfcrt 76T mutant throughout the assessed periods. In addition, all isolates showed ex vivo chloroquine resistance. The pfmdr1 86Y was detected in 1.5% of samples in period 1, and in 25% in period 2. All samples presented the pfmdr1 1246Y. The analysis of pfmdr1 copy number showed amplification in 37.3% in period 1 and in 42% in period 2. Mutations in pfdhfr were shown as follows: 51I in all samples in period 1 and in 81.2% in period 2; 59R in 6.4% in period 2. The pfdhfr 108N and the pfdhps 437G were seen in all samples along time; the pfdhps 540E in 93.7% in period 1 and in 75% in period 2. Conclusions The 76T mutation associated to chloroquine resistance is still present in the parasite population, although this anti-malarial was withdrawn from the chemotherapy of P. falciparum in Brazil in the mid-1980s. All isolates assayed ex vivo for chloroquine showed resistant phenotype and 76T. No association was observed between pfmdr1 mutations and resistance to quinine, mefloquine and artemisinin derivatives. Additionally, the pfdhfr 108N mutation was detected in all samples throughout the evaluated periods, demonstrating fixation of the mutant allele in the parasite population. Changes in Brazilian national guidelines for the malaria chemotherapy in the last 27 years yielded a discreet genetic impact in the parasite population.
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16
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Role of Pfmdr1 in in vitro Plasmodium falciparum susceptibility to chloroquine, quinine, monodesethylamodiaquine, mefloquine, lumefantrine, and dihydroartemisinin. Antimicrob Agents Chemother 2014; 58:7032-40. [PMID: 25199781 DOI: 10.1128/aac.03494-14] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The involvement of Pfmdr1 (Plasmodium falciparum multidrug resistance 1) polymorphisms in antimalarial drug resistance is still debated. Here, we evaluate the association between polymorphisms in Pfmdr1 (N86Y, Y184F, S1034C, N1042D, and D1246Y) and Pfcrt (K76T) and in vitro responses to chloroquine (CQ), mefloquine (MQ), lumefantrine (LMF), quinine (QN), monodesethylamodiaquine (MDAQ), and dihydroartemisinin (DHA) in 174 Plasmodium falciparum isolates from Dakar, Senegal. The Pfmdr1 86Y mutation was identified in 14.9% of the samples, and the 184F mutation was identified in 71.8% of the isolates. No 1034C, 1042N, or 1246Y mutations were detected. The Pfmdr1 86Y mutation was significantly associated with increased susceptibility to MDAQ (P = 0.0023), LMF (P = 0.0001), DHA (P = 0.0387), and MQ (P = 0.00002). The N86Y mutation was not associated with CQ (P = 0.214) or QN (P = 0.287) responses. The Pfmdr1 184F mutation was not associated with various susceptibility responses to the 6 antimalarial drugs (P = 0.168 for CQ, 0.778 for MDAQ, 0.324 for LMF, 0.961 for DHA, 0.084 for QN, and 0.298 for MQ). The Pfmdr1 86Y-Y184 haplotype was significantly associated with increased susceptibility to MDAQ (P = 0.0136), LMF (P = 0.0019), and MQ (P = 0.0001). The additional Pfmdr1 86Y mutation increased significantly the in vitro susceptibility to MDAQ (P < 0.0001), LMF (P < 0.0001), MQ (P < 0.0001), and QN (P = 0.0026) in wild-type Pfcrt K76 parasites. The additional Pfmdr1 86Y mutation significantly increased the in vitro susceptibility to CQ (P = 0.0179) in Pfcrt 76T CQ-resistant parasites.
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Muhamad P, Chaijaroenkul W, Phompradit P, Rueangweerayut R, Tippawangkosol P, Na-Bangchang K. Polymorphic patterns of pfcrt and pfmdr1 in Plasmodium falciparum isolates along the Thai-Myanmar border. Asian Pac J Trop Biomed 2014; 3:931-5. [PMID: 24093782 DOI: 10.1016/s2221-1691(13)60181-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Revised: 10/21/2013] [Accepted: 11/20/2013] [Indexed: 10/26/2022] Open
Abstract
OBJECTIVE To investigate the distribution and patterns of pfcrt and pfmdr1 polymorphisms in Plasmodium falciparum (P. falciparum) isolates collected from the malaria endemic area of Thailand along Thai-Myanmar border. METHODS Dried blood spot samples were collected from 172 falciparum malaria patients prior received treatment. The samples were extracted using chelex to obtain parasite DNA. PCR-RFLP was employed to detect pfcrt mutation at codons 76, 220, 271, 326, 356 and 371, and the pfmdr1 mutation at codon 86. Pfmdr1 gene copy number was determined by SYBR Green I real-time PCR. RESULTS Mutant alleles of pfcrt and wild type allele of pfmdr1 were found in almost all samples. Pfmdr1 gene copy number in isolates collected from all areas ranged from 1.0 to 5.0 copies and proportion of isolates carrying>1 gene copies was 38.1%. The distribution and patterns of pfcrt and pfmdr1 mutations were similar in P. falciparum isolates from all areas. However, significant differences in both number of pfmdr1 copies and prevalence of isolates carrying>1 gene copies were observed among isolates collected from different areas. The median pfmdr1 copy number in P. falciparum collected from Kanchanaburi and Mae Hongson were 2.5 and 2.0, respectively and more than half of the isolates carried>1 gene copies. CONCLUSIONS The observation of pfmdr1 wild type and increasing of gene copy number may suggest declining of artesunate-mefloquine treatment efficacy in P. falciparum isolates in this border area.
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Affiliation(s)
- Phunuch Muhamad
- Chulabhorn International College of Medicine, Thammasat University, Patumthani, Thailand
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Mungthin M, Intanakom S, Suwandittakul N, Suida P, Amsakul S, Sitthichot N, Thammapalo S, Leelayoova S. Distribution of pfmdr1 polymorphisms in Plasmodium falciparum isolated from Southern Thailand. Malar J 2014; 13:117. [PMID: 24670242 PMCID: PMC3986879 DOI: 10.1186/1475-2875-13-117] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2013] [Accepted: 03/22/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Drug resistance in Plasmodium falciparum is a major problem in malaria control especially along the Thai-Myanmar and Thai-Cambodia borders. To date, a few molecular markers have been identified for anti-malarial resistance in P. falciparum, including the P. falciparum chloroquine resistance transporter (pfcrt) and the P. falciparum multidrug resistance 1 (pfmdr1). However no information is available regarding the distribution pattern of these gene polymorphisms in the parasites from the Thai-Malaysia border. This study was conducted to compare the distribution pattern of the pfcrt and pfmdr1 polymorphisms in the parasites from the lower southern provinces, Thai-Malaysia border and the upper southern provinces, Thai-Myanmar border. In addition, in vitro sensitivities of anti-malarial drugs including chloroquine, mefloquine, quinine, and artesunate were determined. METHODS In all, 492 P. falciparum-positive blood samples were collected from the lower southern provinces: Songkhla, Yala and Narathiwas. From the upper southern part of Thailand, Ranong and Chumphon, 66 samples were also collected. Polymorphisms of the pfcrt and the pfmdr1 gene were determined using PCR techniques. In vitro sensitivities of anti-malarial drugs were determined using radioisotopic method. RESULTS All parasites from both areas contained the pfcrt 76 T allele. The pfmdr1 86Y allele was significantly more common in the parasites isolated from the lower southern areas. In contrast, the pfmdr1 184F allele was predominant among the parasites from the upper southern areas especially Ranong. In addition, the parasites from Ranong contained higher copy numbers than the parasites from other provinces. All adapted parasite isolates exhibited CQ-resistant phenotype. Neither QN nor MQ resistance was detected in these isolates. CONCLUSION The parasites from Thai-Malaysia border exhibited different resistant patterns compared to other areas along the international border of Thailand. This information will be useful for anti-malarial drug policy in Thailand.
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Affiliation(s)
- Mathirut Mungthin
- Department of Parasitology, Phramongkutklao College of Medicine, Ratchawithi Rd, Bangkok 10400, Thailand.
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Phompradit P, Muhamad P, Wisedpanichkij R, Chaijaroenkul W, Na-Bangchang K. Four years' monitoring of in vitro sensitivity and candidate molecular markers of resistance of Plasmodium falciparum to artesunate-mefloquine combination in the Thai-Myanmar border. Malar J 2014; 13:23. [PMID: 24423390 PMCID: PMC3896708 DOI: 10.1186/1475-2875-13-23] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 01/09/2014] [Indexed: 12/02/2022] Open
Abstract
Background The decline in efficacy of artesunate (AS) and mefloquine (MQ) is now the major concern in areas along the Thai-Cambodian and Thai-Myanmar borders. Methods The correlation between polymorphisms of pfatp6, pfcrt, pfmdr1 and pfmrp1 genes and in vitro sensitivity of Plasmodium falciparum isolates to the artemisinin-based combination therapy (ACT) components AS and MQ, including the previously used first-line anti-malarial drugs chloroquine (CQ) and quinine (QN) were investigated in a total of 119 P. falciparum isolates collected from patients with uncomplicated P. falciparum infection during 2006–2009. Results Reduced in vitro parasite sensitivity to AS [median (95% CI) IC50 3.4 (3.1-3.7) nM] was found in 42% of the isolates, whereas resistance to MQ [median (95% CI) IC50 54.1 (46.8-61.4) nM] accounted for 58% of the isolates. Amplification of pfmdr1 gene was strongly associated with a decline in susceptibility of P. falciparum isolates to AS, MQ and QN. Significant difference in IC50 values of AS, MQ and QN was observed among isolates carrying one, two, three, and ≥ four gene copies [median (95% CI) AS IC50: 1.6 (1.3-1.9), 1.8 (1.1-2.5), 2.9 (2.1-3.7) and 3.1 (2.5-3.7) nM, respectively; MQ IC50: 19.2 (15.8-22.6), 37.8 (10.7-64.8), 55.3 (47.7-62.9) and 63.6 (49.2-78.0) nM, respectively; and QN IC50: 183.0 (139.9-226.4), 256.4 (83.7-249.1), 329.5 (206.6-425.5) and 420.0 (475.2-475.6) nM, respectively]. The prevalence of isolates which were resistant to QN was reduced from 21.4% during the period 2006–2007 to 6.3% during the period 2008–2009. Pfmdr1 86Y was found to be associated with increased susceptibility of the parasite to MQ and QN. Pfmdr1 1034C was associated with decreased susceptibility to QN. Pfmrp1 191Y and 1390I were associated with increased susceptibility to CQ and QN, respectively. Conclusion High prevalence of CQ and MQ-resistant P. falciparum isolates was observed during the four-year observation period (2006–2009). AS sensitivity was declined, while QN sensitivity was improved. Pfmdr1 and pfmrp1 appear to be the key genes that modulate multidrug resistance in P. falciparum.
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Affiliation(s)
| | | | | | | | - Kesara Na-Bangchang
- Chulabhorn International College of Medicine, Thammasat University (Rangsit Campus), Patumthani 12121, Thailand.
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Krishna S, Pulcini S, Moore CM, Teo BHY, Staines HM. Pumped up: reflections on PfATP6 as the target for artemisinins. Trends Pharmacol Sci 2014; 35:4-11. [DOI: 10.1016/j.tips.2013.10.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 10/11/2013] [Accepted: 10/21/2013] [Indexed: 12/01/2022]
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Na-Bangchang K, Karbwang J. Emerging artemisinin resistance in the border areas of Thailand. Expert Rev Clin Pharmacol 2013; 6:307-22. [PMID: 23656342 DOI: 10.1586/ecp.13.17] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Emergence of artemisinin resistance has been confirmed in Cambodia and the border areas of Thailand, the well-known hotspots of multidrug resistance Plasmodium falciparum. It appears to be spreading to the western border of Thailand along the Thai-Myanmar border, and will probably spread to other endemic areas of the world in the near future. This raises a serious concern on the long-term efficacy of artemisinin-based combination therapies, as these combination therapies currently constitute the last effective and most tolerable treatment for multidrug-resistant Plasmodium falciparum. Attempts have been made by a diverse array of stakeholders to prevent the emergence of new foci of artemisinin resistance, as well as to limit the spread of resistance to the original foci. The success in achieving this goal depends on effective integration of containment and surveillance programs with other malaria control measures, with support from both basic and operational research.
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22
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Rosenthal PJ. The interplay between drug resistance and fitness in malaria parasites. Mol Microbiol 2013; 89:1025-38. [PMID: 23899091 DOI: 10.1111/mmi.12349] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/28/2013] [Indexed: 12/01/2022]
Abstract
Controlling the spread of antimalarial drug resistance, especially resistance of Plasmodium falciparum to artemisinin-based combination therapies, is a high priority. Available data indicate that, as with other microorganisms, the spread of drug-resistant malaria parasites is limited by fitness costs that frequently accompany resistance. Resistance-mediating polymorphisms in malaria parasites have been identified in putative drug transporters and in target enzymes. The impacts of these polymorphisms on parasite fitness have been characterized in vitro and in animal models. Additional insights have come from analyses of samples from clinical studies, both evaluating parasites under different selective pressures and determining the clinical consequences of infection with different parasites. With some exceptions, resistance-mediating polymorphisms lead to malaria parasites that, compared with wild type, grow less well in culture and in animals, and are replaced by wild type when drug pressure diminishes in the clinical setting. In some cases, the fitness costs of resistance may be offset by compensatory mutations that increase virulence or changes that enhance malaria transmission. However, not enough is known about effects of resistance mediators on parasite fitness. A better appreciation of the costs of fitness-mediating mutations will facilitate the development of optimal guidelines for the treatment and prevention of malaria.
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Affiliation(s)
- Philip J Rosenthal
- Department of Medicine, University of California, San Francisco, CA, 94143, USA
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Na-Bangchang K, Muhamad P, Ruaengweerayut R, Chaijaroenkul W, Karbwang J. Identification of resistance of Plasmodium falciparum to artesunate-mefloquine combination in an area along the Thai-Myanmar border: integration of clinico-parasitological response, systemic drug exposure, and in vitro parasite sensitivity. Malar J 2013; 12:263. [PMID: 23898808 PMCID: PMC3737112 DOI: 10.1186/1475-2875-12-263] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 07/19/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND A markedly high failure rate of three-day artesunate-mefloquine was observed in the area along the Thai-Myanmar border. METHODS Identification of Plasmodium falciparum isolates with intrinsic resistance to each component of the artesunate-mefloquine combination was analysed with integrated information on clinico-parasitological response, together with systemic drug exposure (area under blood/plasma concentration-time curves (AUC)) of dihydroartemisinin and mefloquine, and in vitro sensitivity of P. falciparum in a total of 17 out of 29 P. falciparum isolates from patients with acute uncomplicated falciparum malaria. Analysis of the contribution of in vitro parasite sensitivity and systemic drug exposure and relationship with pfmdr1 copy number in the group with sensitive response was performed in 21 of 69 cases. RESULTS Identification of resistance and/or reduced intrinsic parasitocidal activity of artesunate and/or mefloquine without pharmacokinetic or other host-related factors were confirmed in six cases: one with reduced sensitivity to artesunate alone, two with resistance to mefloquine alone, and three with reduced sensitivity to artesunate combined with resistance to mefloquine. Resistance and/or reduced intrinsic parasitocidal activity of mefloquine/artesunate, together with contribution of pharmacokinetic factor of mefloquine and/or artesunate were identified in seven cases: two with resistance to mefloquine alone, and five with resistance to mefloquine combined with reduced sensitivity to artesunate. Pharmacokinetic factor alone contributed to recrudescence in three cases, all of which had inadequate whole blood mefloquine levels (AUC0-7days). Other host-related factors contributed to recrudescence in one case. Amplification of pfmdr1 (increasing of pfmdr1 copy number) is a related molecular marker of artesunate-mefloquine resistance and seems to be a suitable molecular marker to predict occurrence of recrudescence. CONCLUSIONS Despite the evidence of a low level of a decline in sensitivity of P. falciparum isolates to artemisinins in areas along the Thai-Myanmar border, artemisinin-based combination therapy (ACT) would be expected to remain the key anti-malarial drug for treatment of multidrug resistance P. falciparum. Continued monitoring and active surveillance of clinical efficacy of ACT, including identification of true artemisinin resistant parasites, is required for appropriate implementation of malaria control policy in this area.
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Affiliation(s)
- Kesara Na-Bangchang
- International College of Medicine, Thammasat University, Klongluang, Pathumthanee, Thailand.
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The role of Pfmdr1 and Pfcrt in changing chloroquine, amodiaquine, mefloquine and lumefantrine susceptibility in western-Kenya P. falciparum samples during 2008-2011. PLoS One 2013; 8:e64299. [PMID: 23675533 PMCID: PMC3652850 DOI: 10.1371/journal.pone.0064299] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 04/11/2013] [Indexed: 01/18/2023] Open
Abstract
Single Nucleotide Polymorphisms (SNPs) in the Pfmdr1, and Pfcrt, genes of Plasmodium falciparum may confer resistance to a number of anti-malaria drugs. Pfmdr1 86Y and haplotypes at Pfcrt 72-76 have been linked to chloroquine (CQ) as well as amodiaquine (AQ) resistance. mefloquine (MQ) and lumefantrine (LU) sensitivities are linked to Pfmdr1 86Y. Additionally, Pfcrt K76 allele carrying parasites have shown tolerance to LU. We investigated the association between Pfmdr1 86/Pfcrt 72-76 and P. falciparum resistance to CQ, AQ, MQ and LU using field samples collected during 2008–2011 from malaria endemic sites in western Kenya. Genomic DNA from these samples was genotyped to examine SNPs and haplotypes in Pfmdr1 and Pfcrt respectively. Additionally, immediate ex vivo and in vitro drug sensitivity profiles were assessed using the malaria SYBR Green I fluorescence-based assay. We observed a rapid but steady percent increase in wild-type parasites with regard to both Pfmdr1 and Pfcrt between 2008 and 2011 (p<0.0001). Equally, a significant reciprocate decrease in AQ and CQ median IC50 values occurred (p<0.0001) during the same period. Thus, the data in this study point to a significantly rapid change in parasite response to AQ and CQ in the study period. This may be due to releasing of drug pressure on the parasite from reduced use of AQ in the face of increased Artemisinin (ART) Combination Therapy (ACT) administration following the intervention of the Global Fund in 2008. LU has been shown to select for 76K genotypes, thus the observed increase in 76K genotypes coupled with significant cross resistance between LU and MQ, may herald emergence of tolerance against both drugs in future.
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Brown T, Smith LS, Oo EKS, Shawng K, Lee TJ, Sullivan D, Beyrer C, Richards AK. Molecular surveillance for drug-resistant Plasmodium falciparum in clinical and subclinical populations from three border regions of Burma/Myanmar: cross-sectional data and a systematic review of resistance studies. Malar J 2012; 11:333. [PMID: 22992214 PMCID: PMC3518194 DOI: 10.1186/1475-2875-11-333] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Accepted: 08/15/2012] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Confirmation of artemisinin-delayed parasite clearance in Plasmodium falciparum along the Thai-Myanmar border has inspired a global response to contain and monitor drug resistance to avert the disastrous consequences of a potential spread to Africa. However, resistance data from Myanmar are sparse, particularly from high-risk areas where limited health services and decades of displacement create conditions for resistance to spread. Subclinical infections may represent an important reservoir for resistance genes that confer a fitness disadvantage relative to wild-type alleles. This study estimates the prevalence of resistance genotypes in three previously unstudied remote populations in Myanmar and tests the a priori hypothesis that resistance gene prevalence would be higher among isolates collected from subclinical infections than isolates collected from febrile clinical patients. A systematic review of resistance studies is provided for context. METHODS Community health workers in Karen and Kachin States and an area spanning the Indo-Myanmar border collected dried blood spots from 988 febrile clinical patients and 4,591 villagers with subclinical infection participating in routine prevalence surveys. Samples positive for P. falciparum 18 s ribosomal RNA by real-time PCR were genotyped for P. falciparum multidrug resistance protein (pfmdr1) copy number and the pfcrt K76T polymorphism using multiplex real-time PCR. RESULTS Pfmdr1 copy number increase and the pfcrt K76 polymorphism were determined for 173 and 269 isolates, respectively. Mean pfmdr1 copy number was 1.2 (range: 0.7 to 3.7). Pfmdr1 copy number increase was present in 17.5%, 9.6% and 11.1% of isolates from Karen and Kachin States and the Indo-Myanmar border, respectively. Pfmdr1 amplification was more prevalent in subclinical isolates (20.3%) than clinical isolates (6.4%, odds ratio 3.7, 95% confidence interval 1.1 - 12.5). Pfcrt K76T prevalence ranged from 90-100%. CONCLUSIONS Community health workers can contribute to molecular surveillance of drug resistance in remote areas of Myanmar. Marginal and displaced populations under-represented among previous resistance investigations can and should be included in resistance surveillance efforts, particularly once genetic markers of artemisinin-delayed parasite clearance are identified. Subclinical infections may contribute to the epidemiology of drug resistance, but determination of gene amplification from desiccated filter samples requires further validation when DNA concentration is low.
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Affiliation(s)
- Tyler Brown
- Johns Hopkins University School of Medicine, Broadway Research Building, 733 N. Broadway, Suite 147, Baltimore, MD, 21205, USA
- Global Health Access Program, 2550 Ninth Street, Ste 111, Berkeley, CA, 94710, USA
| | - Linda S Smith
- Global Health Access Program, 2550 Ninth Street, Ste 111, Berkeley, CA, 94710, USA
| | - Eh Kalu Shwe Oo
- Karen Department of Health and Welfare, PO Box 189, Mae Sot, Tak, 63110, Thailand
| | - Kum Shawng
- Office of the Director of the Health Department, Kachin Baptist Convention 135/Shan Su (South), Myitkyina, Kachin State, Myanmar
| | - Thomas J Lee
- Global Health Access Program, 2550 Ninth Street, Ste 111, Berkeley, CA, 94710, USA
- School of Medicine, University of California at Los Angeles, 924 Westwood Blvd, Suite 300, Los Angeles, CA, 90024, USA
| | - David Sullivan
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health 615 North Wolfe St, Room E5628, Baltimore, MD, 21205, USA
| | - Chris Beyrer
- Department of Epidemiology Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe St., Suite E7152, Baltimore, MD, 21205, USA
| | - Adam K Richards
- Global Health Access Program, 2550 Ninth Street, Ste 111, Berkeley, CA, 94710, USA
- Department of General Internal Medicine and Health Services Research, University of California at Los Angeles, 911 Broxton Ave, Los Angeles, CA, 90025, USA
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Wurtz N, Fall B, Pascual A, Diawara S, Sow K, Baret E, Diatta B, Fall KB, Mbaye PS, Fall F, Diémé Y, Rogier C, Bercion R, Briolant S, Wade B, Pradines B. Prevalence of molecular markers of Plasmodium falciparum drug resistance in Dakar, Senegal. Malar J 2012; 11:197. [PMID: 22694921 PMCID: PMC3470961 DOI: 10.1186/1475-2875-11-197] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Accepted: 06/02/2012] [Indexed: 12/03/2022] Open
Abstract
Background As a result of the widespread resistance to chloroquine and sulphadoxine-pyrimethamine, artemisinin-based combination therapy (ACT) (including artemether-lumefantrine and artesunate-amodiaquine) has been recommended as a first-line anti-malarial regimen in Senegal since 2006. Intermittent preventive treatments with anti-malarial drugs based on sulphadoxine-pyrimethamine are also given to children or pregnant women once per month during the transmission season. Since 2006, there have been very few reports on the susceptibility of Plasmodium falciparum to anti-malarial drugs. To estimate the prevalence of resistance to several anti-malarial drugs since the introduction of the widespread use of ACT, the presence of molecular markers associated with resistance to chloroquine and sulphadoxine-pyrimethamine was assessed in local isolates at the military hospital of Dakar. Methods The prevalence of genetic polymorphisms in genes associated with anti-malarial drug resistance, i.e., Pfcrt, Pfdhfr, Pfdhps and Pfmdr1, and the copy number of Pfmdr1 were evaluated for a panel of 174 isolates collected from patients recruited at the military hospital of Dakar from 14 October 2009 to 19 January 2010. Results The Pfcrt 76T mutation was identified in 37.2% of the samples. The Pfmdr1 86Y and 184F mutations were found in 16.6% and 67.6% of the tested samples, respectively. Twenty-eight of the 29 isolates with the 86Y mutation were also mutated at codon 184. Only one isolate (0.6%) had two copies of Pfmdr1. The Pfdhfr 108N/T, 51I and 59R mutations were identified in 82.4%, 83.5% and 74.1% of the samples, respectively. The double mutant (108N and 51I) was detected in 83.5% of the isolates, and the triple mutant (108N, 51I and 59R) was detected in 75.3%. The Pfdhps 437G, 436F/A and 613S mutations were found in 40.2%, 35.1% and 1.8% of the samples, respectively. There was no double mutant (437G and 540E) or no quintuple mutant (Pfdhfr 108N, 51I and 59R and Pfdhps 437G and 540E). The prevalence of the quadruple mutant (Pfdhfr 108N, 51I and 59R and Pfdhps 437G) was 36.5%. Conclusions Since 2004, the prevalence of chloroquine resistance had decreased. The prevalence of isolates with high-level pyrimethamine resistance is 83.5%. The prevalence of isolates resistant to sulphadoxine is 40.2%. However, no quintuple mutant (Pfdhfr 108N, 51I and 59R and Pfdhps 437G and 540E), which is associated with a high level of sulphadoxine-pyrimethamine resistance, has been identified to date. The resistance to amodiaquine remains moderate.
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Affiliation(s)
- Nathalie Wurtz
- Unité de parasitologie, UMR 6236, Institut de recherche biomédicale des armées, Marseille, France
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Wang Z, Parker D, Meng H, Wu L, Li J, Zhao Z, Zhang R, Fan Q, Wang H, Cui L, Yang Z. In vitro sensitivity of Plasmodium falciparum from China-Myanmar border area to major ACT drugs and polymorphisms in potential target genes. PLoS One 2012; 7:e30927. [PMID: 22701513 PMCID: PMC3365119 DOI: 10.1371/journal.pone.0030927] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Accepted: 12/25/2011] [Indexed: 01/16/2023] Open
Abstract
Drug resistance has always been one of the most important impediments to global malaria control. Artemisinin resistance has recently been confirmed in the Greater Mekong Subregion (GMS) and efforts for surveillance and containment are intensified. To determine potential mechanisms of artemisinin resistance and monitor the emergence and spread of resistance in other regions of the GMS, we investigated the in vitro sensitivity of 51 culture-adapted parasite isolates from the China-Myanmar border area to four drugs. The 50% inhibitory concentrations (IC₅₀s) of dihydroartemisinin, mefloquine and lumefantrine were clustered in a relatively narrow, 3- to 6-fold range, whereas the IC₅₀ range of artesunate was 12-fold. We assessed the polymorphisms of candidate resistance genes pfcrt, pfmdr1, pfATP6, pfmdr6 and pfMT (a putative metabolite/drug transporter). The K76T mutation in pfcrt reached fixation in the study parasite population, whereas point mutations in pfmdr1 and pfATP6 had low levels of prevalence. In addition, pfmdr1 gene amplification was not detected. None of the mutations in pfmdr1 and pfATP6 was associated significantly with in vitro sensitivity to artemisinin derivatives. The ABC transporter gene pfmdr6 harbored two point mutations, two indels, and number variations in three simple repeats. Only the length variation in a microsatellite repeat appeared associated with altered sensitivity to dihydroartemisinin. The PfMT gene had two point mutations and one codon deletion; the I30N and N496- both reached high levels of prevalence. However, none of the SNPs or haplotypes in PfMT were correlated significantly with resistance to the four tested drugs. Compared with other parasite populations from the GMS, our studies revealed drastically different genotype and drug sensitivity profiles in parasites from the China-Myanmar border area, where artemisinins have been deployed extensively for over 30 years.
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Affiliation(s)
- Zenglei Wang
- Department of Entomology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Daniel Parker
- Department of Entomology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Hao Meng
- Department of Entomology, Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Parasitology, Kunming Medical University, Kunming, Yunnan, China
| | - Lanou Wu
- Department of Pharmacology, Kunming Medical University, Kunming, Yunnan, China
| | - Jia Li
- Department of Parasitology, Kunming Medical University, Kunming, Yunnan, China
| | - Zhen Zhao
- Department of Parasitology, Kunming Medical University, Kunming, Yunnan, China
| | - Rongping Zhang
- Department of Pharmaceutical Chemistry, Kunming Medical University, Kunming, Yunnan, China
| | - Qi Fan
- Dalian Institute of Biotechnology, Dalian, Liaoning, China
| | - Haiyan Wang
- Department of Statistics, Kansas State University, Manhattan, Kansas, United States of America
| | - Liwang Cui
- Department of Entomology, Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail: (LC); (ZY)
| | - Zhaoqing Yang
- Department of Parasitology, Kunming Medical University, Kunming, Yunnan, China
- * E-mail: (LC); (ZY)
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Mullié C, Jonet A, Desgrouas C, Taudon N, Sonnet P. Differences in anti-malarial activity of 4-aminoalcohol quinoline enantiomers and investigation of the presumed underlying mechanism of action. Malar J 2012; 11:65. [PMID: 22401346 PMCID: PMC3314553 DOI: 10.1186/1475-2875-11-65] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 03/08/2012] [Indexed: 11/10/2022] Open
Abstract
Background A better anti-malarial efficiency and lower neurotoxicity have been reported for mefloquine (MQ) (+)- enantiomer. However, the importance of stereoselectivity remains poorly understood as the anti-malarial activity of pure enantiomer MQ analogues has never been described. Building on these observations, a series of enantiopure 4-aminoalcohol quinoline derivatives has previously been synthesized to optimize the efficiency and reduce possible adverse effects. Their in vitro activity on Plasmodium falciparum W2 and 3D7 strains is reported here along with their inhibition of β-haematin formation and peroxidative degradation of haemin, two possible mechanisms of action of anti-malarial drugs. Results The (S)-enantiomers of this series of 4-aminoalcohol quinoline derivatives were found to be at least as effective as both chloroquine (CQ) and MQ. The derivative with a 5-carbon side-chain length was the more efficient on both P. falciparum strains. (R )-enantiomers displayed an activity decreased by 2 to 15-fold as compared to their (S) counterparts. The inhibition of β-haematin formation was significantly stronger with all tested compounds than with MQ, irrespective of the stereochemistry. Similarly, the inhibition of haemin peroxidation was significantly higher for both (S) and (R)-enantiomers of derivatives with a side-chain length of five or six carbons than for MQ and CQ. Conclusions The prominence of stereochemistry in the anti-malarial activity of 4-aminoalcohol quinoline derivatives is confirmed. The inhibition of β-haematin formation and haemin peroxidation can be put forward as presumed mechanisms of action but do not account for the stereoselectivity of action witnessed in vitro.
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Affiliation(s)
- Catherine Mullié
- Laboratoire des Glucides, UMR-CNRS 6219, UFR de Pharmacie, 1 rue des Louvels, 80037 Amiens Cedex 1, France.
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Lack of association of the S769N mutation in Plasmodium falciparum SERCA (PfATP6) with resistance to artemisinins. Antimicrob Agents Chemother 2012; 56:2546-52. [PMID: 22354307 DOI: 10.1128/aac.05943-11] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The recent emergence of artemisinin (ART) resistance in Plasmodium falciparum in western Cambodia, manifested as delayed parasite clearance, is a big threat to the long-term efficacy of this family of antimalarial drugs. Among the multiple candidate genes associated with ART resistance in P. falciparum, the sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase PfATP6 has been postulated as a specific target of ARTs. The PfATP6 gene harbors multiple single-nucleotide polymorphisms in field parasite populations, and S769N has been associated with decreased sensitivity to artemether in parasite populations from French Guiana. In this study, we used an allelic exchange strategy to engineer parasite lines carrying the S769N mutations in P. falciparum strain 3D7 and evaluated whether introduction of this mutation modulated parasite sensitivity to ART derivatives. Using three transgenic lines carrying the 769N mutation and two transgenic lines carrying the wild-type 769S as controls, we found that S769N did not affect PfATP6 gene expression. We compared the sensitivities of these parasite lines to three ART derivatives, artemether, artesunate, and dihydroartemisinin, in 18 biological experiments and detected no significant effect of the S769N mutation on parasite response to these ART derivatives. This study provides further evidence for the lack of association of PfATP6 with ART resistance.
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Polymorphisms of the pfmdr1 but not the pfnhe-1 gene is associated with in vitro quinine sensitivity in Thai isolates of Plasmodium falciparum. Malar J 2012; 11:7. [PMID: 22221394 PMCID: PMC3287963 DOI: 10.1186/1475-2875-11-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 07/12/2011] [Accepted: 01/05/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The emergence of Plasmodium falciparum resistance to most currently used anti-malarial drugs is a major problem in malaria control along the Thai-Myanmar and Thai-Cambodia borders. Quinine (QN) with tetracycline/doxycycline has been used as the second-line treatment for uncomplicated falciparum malaria. In addition, QN monotherapy has been the first-line treatment for falciparum malaria in pregnant women. However, reduced in vitro and in vivo responses to QN have been reported. To date, a few genetic markers for QN resistance have been proposed including Plasmodium falciparum chloroquine resistance transporter (pfcrt), P. falciparum multidrug resistance 1 (pfmdr1), and P. falciparum Na+/H+ exchanger (pfnhe-1). This study was to investigate the role of the pfmdr1 and pfnhe-1 gene on in vitro QN sensitivity in Thai isolates of P. falciparum. METHODS Eighty-five Thai isolates of P. falciparum from the Thai-Myanmar and Thai-Cambodia borders from 2003-2008 were determined for in vitro QN sensitivity using radioisotopic assay. Polymorphisms of the pfmdr1 and pfnhe-1 gene were determined by PCR-RFLP and sequence analysis. Associations between the in vitro QN sensitivity and the polymorphisms of the pfmdr1 and pfnhe-1 gene were evaluated. RESULTS The mean QN IC50 was 202.8 nM (range 25.7-654.4 nM). Only four isolates were QN resistant when the IC50 of >500 nM was used as the cut-off point. Significant associations were found between the pfmdr1 mutations at codons N86Y and N1042D and in vitro QN sensitivity. However, no associations with the number of DNNND, DDNNNDNHNDD, and NHNDNHNNDDD repeats in the microsatellite ms4760 of the pfnhe-1 gene were identified. CONCLUSION Data from the present study put doubt regarding the pfnhe-1 gene as to whether it could be used as the suitable marker for QN resistance in Thailand. In contrast, it confirms the influence of the pfmdr1 gene on in vitro QN sensitivity.
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