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Sifuna PM, Mbinji M, Lucas TO, Onyango I, Akala HM, Waitumbi JN, Ogutu BR, Hutter JN, Otieno W. The Walter Reed Project, Kisumu Field Station: Impact of Research on Malaria Policy, Management, and Prevention. Am J Trop Med Hyg 2024; 110:1069-1079. [PMID: 38653233 PMCID: PMC11154051 DOI: 10.4269/ajtmh.23-0115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 02/16/2024] [Indexed: 04/25/2024] Open
Abstract
The Walter Reed Project is a collaboration between the Walter Reed Army Institute of Research of the United States Department of Defense and the Kenya Medical Research Institute. The Kisumu field station, comprising four campuses, has until recently been devoted primarily to research on malaria countermeasures. The Kombewa Clinical Research Center is dedicated to conducting regulated clinical trials of therapeutic and vaccine candidates in development. The center's robust population-based surveillance platform, along with an active community engagement strategy, guarantees consistent recruitment and retention of participants in clinical trials. The Malaria Diagnostic Center, backed by WHO-certified microscopists and a large malaria blood film collection, champions high-quality malaria diagnosis and strict quality assurance through standardized microscopy trainings. The Malaria Drug Resistance Laboratory leverages cutting-edge technology such as real-time Polymerase Chain Reaction (qPCR) to conduct comprehensive research on resistance markers and obtain information on drug efficacy. The laboratory has been working on validating artemisinin resistance markers and improving tracking methods for current and future antimalarial compounds. Finally, the Basic Science Laboratory employs advanced genomic technology to examine endpoints such as immunogenicity and genomic fingerprinting for candidate drugs and vaccine efficacy. Herein, we examine the site's significant contributions to malaria policy, management, and prevention practices in Kenya and around the world.
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Affiliation(s)
- Peter M Sifuna
- Kenya Medical Research Institute, Kisumu, Kenya
- U.S. Army Medical Research Directorate-Africa, Kisumu, Kenya
| | - Michal Mbinji
- Kenya Medical Research Institute, Kisumu, Kenya
- U.S. Army Medical Research Directorate-Africa, Kisumu, Kenya
| | - Tina O Lucas
- Kenya Medical Research Institute, Kisumu, Kenya
- U.S. Army Medical Research Directorate-Africa, Kisumu, Kenya
| | - Irene Onyango
- Kenya Medical Research Institute, Kisumu, Kenya
- U.S. Army Medical Research Directorate-Africa, Kisumu, Kenya
| | - Hoseah M Akala
- Kenya Medical Research Institute, Kisumu, Kenya
- U.S. Army Medical Research Directorate-Africa, Kisumu, Kenya
| | - John N Waitumbi
- Kenya Medical Research Institute, Kisumu, Kenya
- U.S. Army Medical Research Directorate-Africa, Kisumu, Kenya
| | - Bernhards R Ogutu
- Kenya Medical Research Institute, Kisumu, Kenya
- U.S. Army Medical Research Directorate-Africa, Kisumu, Kenya
| | - Jack N Hutter
- U.S. Army Medical Research Directorate-Africa, Kisumu, Kenya
| | - Walter Otieno
- Kenya Medical Research Institute, Kisumu, Kenya
- U.S. Army Medical Research Directorate-Africa, Kisumu, Kenya
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Konaté-Touré A, Gnagne AP, Bedia-Tanoh AV, Menan EIH, Yavo W. Increase of Plasmodium falciparum parasites carrying lumefantrine-tolerance molecular markers and lack of South East Asian pfk13 artemisinin-resistance mutations in samples collected from 2013 to 2016 in Côte d'Ivoire. J Parasit Dis 2024; 48:59-66. [PMID: 38440764 PMCID: PMC10908703 DOI: 10.1007/s12639-023-01640-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 12/21/2023] [Indexed: 03/06/2024] Open
Abstract
One of the major obstacles to malaria elimination in the world is the resistance in Plasmodium falciparum to most antimalarial drugs. This study aimed to estimate the prevalence of molecular markers of antimalarial drugs resistance in Côte d'Ivoire. Samples were collected from 2013 to 2016 from asymptomatic and symptomatic subjects in Abengourou, Abidjan, Grand Bassam, and San Pedro. A total of 704 participants aged between 1 year and 65 years (Mean age: 9 years ± 7.7) were enrolled. All the dried filter paper blood spots were genotyped by sequencing. Plasmodium falciparum kelch propeller domain 13 (pfk13) gene were analyzed for all the samples, while 344 samples were examined for Plasmodium falciparum multi-drug resistance 1 (pfmdr1). Overall, the success rate of molecular tests was 98.8% (340/344), 99.1% (341/344), and 94.3% (664/704) for pfmdr1 N86Y, pfmdr1 Y184F, and pfk13 genes respectively. Molecular analysis revealed twenty (5.9%; 20/340) and 219 (64.2%; 219/341) mutant alleles for pfmdr1 86Y and pfmdr1 184 F, respectively. Twenty-nine mutations in pfk13 gene (4.4%; 29/664) with 2.7% (18/664) of non-synonymous mutations was found. None of the mutations previously described in South East Asia (SEA) involved in P. falciparum resistance to artemisinin derivatives were observed in this study. According to year of collection, a decrease of the prevalence of pfk13 mutation (from 3.6 to 1.8%) and pfmdr1 N86Y mutation (from 8.5 to 4.5%) and an increase of mutant allele of pfmdr1 Y184F proportion (from 39.8 to 66.4%) were found. Comparing to previous studies in the country, this study showed an increase in lumefantrine tolerance of P. falciparum strains. This demonstrates the importance of establishing a strong system for molecular surveillance of malaria in Côte d'Ivoire.
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Affiliation(s)
- Abibatou Konaté-Touré
- Department of Parasitology, Mycology, Animal Biology and, Zoology, Felix Houphouët-Boigny University, BPV 34, Abidjan, Côte d’Ivoire
- Malaria Research and Control Centre, National Institute of Public Health, BPV 47, Abidjan, Côte d’Ivoire
| | - Akpa Paterne Gnagne
- Malaria Research and Control Centre, National Institute of Public Health, BPV 47, Abidjan, Côte d’Ivoire
| | - Akoua Valérie Bedia-Tanoh
- Department of Parasitology, Mycology, Animal Biology and, Zoology, Felix Houphouët-Boigny University, BPV 34, Abidjan, Côte d’Ivoire
- Malaria Research and Control Centre, National Institute of Public Health, BPV 47, Abidjan, Côte d’Ivoire
| | - Eby Ignace Hervé Menan
- Department of Parasitology, Mycology, Animal Biology and, Zoology, Felix Houphouët-Boigny University, BPV 34, Abidjan, Côte d’Ivoire
| | - William Yavo
- Department of Parasitology, Mycology, Animal Biology and, Zoology, Felix Houphouët-Boigny University, BPV 34, Abidjan, Côte d’Ivoire
- Malaria Research and Control Centre, National Institute of Public Health, BPV 47, Abidjan, Côte d’Ivoire
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Jeang B, Zhong D, Lee MC, Atieli H, Yewhalaw D, Yan G. Molecular surveillance of Kelch 13 polymorphisms in Plasmodium falciparum isolates from Kenya and Ethiopia. Malar J 2024; 23:36. [PMID: 38287365 PMCID: PMC10823687 DOI: 10.1186/s12936-023-04812-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 11/30/2023] [Indexed: 01/31/2024] Open
Abstract
BACKGROUND Timely molecular surveillance of Plasmodium falciparum kelch 13 (k13) gene mutations is essential for monitoring the emergence and stemming the spread of artemisinin resistance. Widespread artemisinin resistance, as observed in Southeast Asia, would reverse significant gains that have been made against the malaria burden in Africa. The purpose of this study was to assess the prevalence of k13 polymorphisms in western Kenya and Ethiopia at sites representing varying transmission intensities between 2018 and 2022. METHODS Dried blood spot samples collected through ongoing passive surveillance and malaria epidemiological studies, respectively, were investigated. The k13 gene was genotyped in P. falciparum isolates with high parasitaemia: 775 isolates from four sites in western Kenya (Homa Bay, Kakamega, Kisii, and Kombewa) and 319 isolates from five sites across Ethiopia (Arjo, Awash, Gambella, Dire Dawa, and Semera). DNA sequence variation and neutrality were analysed within each study site where mutant alleles were detected. RESULTS Sixteen Kelch13 haplotypes were detected in this study. Prevalence of nonsynonymous k13 mutations was low in both western Kenya (25/783, 3.19%) and Ethiopia (5/319, 1.57%) across the study period. Two WHO-validated mutations were detected: A675V in three isolates from Kenya and R622I in four isolates from Ethiopia. Seventeen samples from Kenya carried synonymous mutations (2.17%). No synonymous mutations were detected in Ethiopia. Genetic variation analyses and tests of neutrality further suggest an excess of low frequency polymorphisms in each study site. Fu and Li's F test statistic in Semera was 0.48 (P > 0.05), suggesting potential population selection of R622I, which appeared at a relatively high frequency (3/22, 13.04%). CONCLUSIONS This study presents an updated report on the low frequency of k13 mutations in western Kenya and Ethiopia. The WHO-validated R622I mutation, which has previously only been reported along the north-west border of Ethiopia, appeared in four isolates collected from eastern Ethiopia. The rapid expansion of R622I across Ethiopia signals the need for enhanced monitoring of the spread of drug-resistant P. falciparum parasites in East Africa. Although ACT remains currently efficacious in the study areas, continued surveillance is necessary to detect early indicators of artemisinin partial resistance.
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Affiliation(s)
- Brook Jeang
- Program in Public Health, University of California Irvine, Irvine, CA, USA
| | - Daibin Zhong
- Program in Public Health, University of California Irvine, Irvine, CA, USA
| | - Ming-Chieh Lee
- Program in Public Health, University of California Irvine, Irvine, CA, USA
| | - Harrysone Atieli
- School of Public Health and Community Development, Maseno University, Kisumu, Kenya
- International Center of Excellence for Malaria Research, Tom Mboya University College, Homa Bay, Kenya
| | - Delenasaw Yewhalaw
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia
- Tropical and Infectious Diseases Research Center, Jimma University, Jimma, Ethiopia
| | - Guiyun Yan
- Program in Public Health, University of California Irvine, Irvine, CA, USA.
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Argyropoulos DC, Tan MH, Adobor C, Mensah B, Labbé F, Tiedje KE, Koram KA, Ghansah A, Day KP. Performance of SNP barcodes to determine genetic diversity and population structure of Plasmodium falciparum in Africa. Front Genet 2023; 14:1071896. [PMID: 37323661 PMCID: PMC10267394 DOI: 10.3389/fgene.2023.1071896] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 05/17/2023] [Indexed: 06/17/2023] Open
Abstract
Panels of informative biallelic single nucleotide polymorphisms (SNPs) have been proposed to be an economical method to fast-track the population genetic analysis of Plasmodium falciparum in malaria-endemic areas. Whilst used successfully in low-transmission areas where infections are monoclonal and highly related, we present the first study to evaluate the performance of these 24- and 96-SNP molecular barcodes in African countries, characterised by moderate-to-high transmission, where multiclonal infections are prevalent. For SNP barcodes it is generally recommended that the SNPs chosen i) are biallelic, ii) have a minor allele frequency greater than 0.10, and iii) are independently segregating, to minimise bias in the analysis of genetic diversity and population structure. Further, to be standardised and used in many population genetic studies, these barcodes should maintain characteristics i) to iii) across various iv) geographies and v) time points. Using haplotypes generated from the MalariaGEN P. falciparum Community Project version six database, we investigated the ability of these two barcodes to fulfil these criteria in moderate-to-high transmission African populations in 25 sites across 10 countries. Predominantly clinical infections were analysed, with 52.3% found to be multiclonal, generating high proportions of mixed-allele calls (MACs) per isolate thereby impeding haplotype construction. Of the 24- and 96-SNPs, loci were removed if they were not biallelic and had low minor allele frequencies in all study populations, resulting in 20- and 75-SNP barcodes respectively for downstream population genetics analysis. Both SNP barcodes had low expected heterozygosity estimates in these African settings and consequently biased analyses of similarity. Both minor and major allele frequencies were temporally unstable. These SNP barcodes were also shown to identify weak genetic differentiation across large geographic distances based on Mantel Test and DAPC. These results demonstrate that these SNP barcodes are vulnerable to ascertainment bias and as such cannot be used as a standardised approach for malaria surveillance in moderate-to-high transmission areas in Africa, where the greatest genomic diversity of P. falciparum exists at local, regional and country levels.
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Affiliation(s)
- Dionne C. Argyropoulos
- Department of Microbiology and Immunology, Bio21 Institute and Peter Doherty Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - Mun Hua Tan
- Department of Microbiology and Immunology, Bio21 Institute and Peter Doherty Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - Courage Adobor
- Department of Parasitology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Accra, Ghana
| | - Benedicta Mensah
- Department of Parasitology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Accra, Ghana
| | - Frédéric Labbé
- Department of Ecology and Evolution, The University of Chicago, Chicago, IL, United States
| | - Kathryn E. Tiedje
- Department of Microbiology and Immunology, Bio21 Institute and Peter Doherty Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - Kwadwo A. Koram
- Epidemiology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Anita Ghansah
- Department of Parasitology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Accra, Ghana
| | - Karen P. Day
- Department of Microbiology and Immunology, Bio21 Institute and Peter Doherty Institute, The University of Melbourne, Melbourne, VIC, Australia
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Topazian HM, Moser KA, Ngasala B, Oluoch PO, Forconi CS, Mhamilawa LE, Aydemir O, Kharabora O, Deutsch-Feldman M, Read AF, Denton M, Lorenzo A, Mideo N, Ogutu B, Moormann AM, Mårtensson A, Odwar B, Bailey JA, Akala H, Ong'echa JM, Juliano JJ. Low Complexity of Infection Is Associated With Molecular Persistence of Plasmodium falciparum in Kenya and Tanzania. FRONTIERS IN EPIDEMIOLOGY 2022; 2:852237. [PMID: 38455314 PMCID: PMC10910917 DOI: 10.3389/fepid.2022.852237] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 05/06/2022] [Indexed: 03/09/2024]
Abstract
Background Plasmodium falciparum resistance to artemisinin-based combination therapies (ACTs) is a threat to malaria elimination. ACT-resistance in Asia raises concerns for emergence of resistance in Africa. While most data show high efficacy of ACT regimens in Africa, there have been reports describing declining efficacy, as measured by both clinical failure and prolonged parasite clearance times. Methods Three hundred children aged 2-10 years with uncomplicated P. falciparum infection were enrolled in Kenya and Tanzania after receiving treatment with artemether-lumefantrine. Blood samples were taken at 0, 24, 48, and 72 h, and weekly thereafter until 28 days post-treatment. Parasite and host genetics were assessed, as well as clinical, behavioral, and environmental characteristics, and host anti-malarial serologic response. Results While there was a broad range of clearance rates at both sites, 85% and 96% of Kenyan and Tanzanian samples, respectively, were qPCR-positive but microscopy-negative at 72 h post-treatment. A greater complexity of infection (COI) was negatively associated with qPCR-detectable parasitemia at 72 h (OR: 0.70, 95% CI: 0.53-0.94), and a greater baseline parasitemia was marginally associated with qPCR-detectable parasitemia (1,000 parasites/uL change, OR: 1.02, 95% CI: 1.01-1.03). Demographic, serological, and host genotyping characteristics showed no association with qPCR-detectable parasitemia at 72 h. Parasite haplotype-specific clearance slopes were grouped around the mean with no association detected between specific haplotypes and slower clearance rates. Conclusions Identifying risk factors for slow clearing P. falciparum infections, such as COI, are essential for ongoing surveillance of ACT treatment failure in Kenya, Tanzania, and more broadly in sub-Saharan Africa.
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Affiliation(s)
- Hillary M. Topazian
- Department of Infectious Disease Epidemiology, Imperial College, London, United Kingdom
| | - Kara A. Moser
- Institute for Global Health and Infectious Diseases, University of North Carolina, Chapel Hill, NC, United States
| | - Billy Ngasala
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Peter O. Oluoch
- Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, United States
- Center for Global Health Research, Kenyan Medical Research Institute, Kisumu, Kenya
| | - Catherine S. Forconi
- Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, United States
| | - Lwidiko E. Mhamilawa
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
- Department of Women's and Children's Health, International Maternal and Child Health, Uppsala University, Uppsala, Sweden
| | - Ozkan Aydemir
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, United States
| | - Oksana Kharabora
- Institute for Global Health and Infectious Diseases, University of North Carolina, Chapel Hill, NC, United States
| | - Molly Deutsch-Feldman
- Department of Epidemiology, Gillings School of Global Public Health, Chapel Hill, NC, United States
| | - Andrew F. Read
- Department of Entomology, Penn State University, University Park, PA, United States
| | - Madeline Denton
- Institute for Global Health and Infectious Diseases, University of North Carolina, Chapel Hill, NC, United States
| | - Antonio Lorenzo
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
| | - Nicole Mideo
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
| | - Bernhards Ogutu
- Center for Global Health Research, Kenyan Medical Research Institute, Kisumu, Kenya
| | - Ann M. Moormann
- Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, United States
| | - Andreas Mårtensson
- Department of Women's and Children's Health, International Maternal and Child Health, Uppsala University, Uppsala, Sweden
| | - Boaz Odwar
- Center for Global Health Research, Kenyan Medical Research Institute, Kisumu, Kenya
| | - Jeffrey A. Bailey
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, United States
| | - Hoseah Akala
- Center for Global Health Research, Kenyan Medical Research Institute, Kisumu, Kenya
| | | | - Jonathan J. Juliano
- Institute for Global Health and Infectious Diseases, University of North Carolina, Chapel Hill, NC, United States
- Department of Epidemiology, Gillings School of Global Public Health, Chapel Hill, NC, United States
- Division of Infectious Diseases, School of Medicine, University of North Carolina, Chapel Hill, NC, United States
- Curriculum in Genetics and Molecular Biology, School of Medicine, University of North Carolina, Chapel Hill, NC, United States
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Targeted Amplicon Deep Sequencing for Monitoring Antimalarial Resistance Markers in Western Kenya. Antimicrob Agents Chemother 2022; 66:e0194521. [PMID: 35266823 PMCID: PMC9017353 DOI: 10.1128/aac.01945-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Molecular surveillance of Plasmodium falciparum parasites is important to track emerging and new mutations and trends in established mutations and should serve as an early warning system for antimalarial resistance. Dried blood spots were obtained from a Plasmodium falciparum malaria survey in school children conducted across eight counties in western Kenya in 2019. Real-time PCR identified 500 P. falciparum-positive samples that were amplified at five drug resistance loci for targeted amplicon deep sequencing (TADS). The absence of important kelch 13 mutations was similar to previous findings in Kenya pre-2019, and low-frequency mutations were observed in codons 569 and 578. The chloroquine resistance transporter gene codons 76 and 145 were wild type, indicating that the parasites were chloroquine and piperaquine sensitive, respectively. The multidrug resistance gene 1 haplotypes based on codons 86, 184, and 199 were predominantly present in mixed infections with haplotypes NYT and NFT, driven by the absence of chloroquine pressure and the use of lumefantrine, respectively. The sulfadoxine-pyrimethamine resistance profile was a “superresistant” combination of triple mutations in both Pfdhfr (51I 59R 108N) and Pfdhps (436H 437G 540E), rendering sulfadoxine-pyrimethamine ineffective. TADS highlighted the low-frequency variants, allowing the early identification of new mutations, Pfmdr1 codon 199S and Pfdhfr codon 85I and emerging 164L mutations. The added value of TADS is its accuracy in identifying mixed-genotype infections and for high-throughput monitoring of antimalarial resistance markers.
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Berzosa P, Molina de la Fuente I, Ta-Tang TH, González V, García L, Rodríguez-Galet A, Díaz-Regañón R, Galán R, Cerrada-Gálvez L, Ncogo P, Riloha M, Benito A. Temporal evolution of the resistance genotypes of Plasmodium falciparum in isolates from Equatorial Guinea during 20 years (1999 to 2019). Malar J 2021; 20:463. [PMID: 34906159 PMCID: PMC8670137 DOI: 10.1186/s12936-021-04000-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 12/01/2021] [Indexed: 11/18/2022] Open
Abstract
Background Malaria is one of the deadliest diseases in the world, particularly in Africa. As such, resistance to anti-malarial drugs is one of the most important problems in terms of global malaria control. This study assesses the evolution of the different resistance markers over time and the possible influence of interventions and treatment changes that have been made in Equatorial Guinea. Methods A total of 1223 biological samples obtained in the period 1999 to 2019 were included in the study. Screening for mutations in the pfdhfr, pfdhps, pfmdr1, and pfcrt genes was carried out by nested PCR and restriction-fragment length polymorphisms (RFLPs), and the study of pfk13 genes was carried out by nested PCR, followed by sequencing to determine the presence of mutations. Results The partially and fully resistant haplotypes (pfdhfr + pfdhps) were found to increase over time. Moreover, in 2019, the fully resistant haplotype was found to be increasing, although its super-resistant counterpart remains much less prevalent. A continued decline in pfmdr1 and pfcrt gene mutations over time was also found. The number of mutations detected in pfk13 has increased since 2008, when artemisinin-based combination therapy (ACT) were first introduced, with more mutations being observed in 2019, with two synonymous and five non-synonymous mutations being detected, although these are not related to resistance to ACT. In addition, the non-synonymous A578S mutation, which is the most frequent on the African continent, was detected in 2013, although not in the following years. Conclusions Withdrawal of the use of chloroquine (CQ) as a treatment in Equatorial Guinea has been shown to be effective over time, as wild-type parasite populations outnumber mutant populations. The upward trend observed in sulfadoxine-pyrimethamine (SP) resistance markers suggest its misuse, either alone or in combination with artesunate (AS) or amodiaquine (AQ), in some areas of the country, as was found in a previous study conducted by this group, which allows selective pressure from SP to continue. Single nucleotide polymorphisms (SNPs) 540E and 581G do not exceed the limit of 50 and 10%, respectively, thus meaning that SP is still effective as an intermittent preventive treatment (IPT) in this country. As for the pfk13 gene, no mutations have been detected in relation to resistance to ACT. However, in 2019 there is a greater accumulation of non-synonymous mutations compared to years prior to 2008. Graphical Abstract ![]()
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Affiliation(s)
- Pedro Berzosa
- National Centre of Tropical Medicine-Institute of Health Carlos III, Madrid, Spain.
| | - Irene Molina de la Fuente
- Department of Biomedicine and Biotechnology, University of Alcalá and National Centre of Tropical Medicine-Institute of Health Carlos III, Madrid, Spain
| | - Thuy-Huong Ta-Tang
- National Centre of Tropical Medicine-Institute of Health Carlos III, Madrid, Spain
| | - Vicenta González
- National Centre of Tropical Medicine-Institute of Health Carlos III, Madrid, Spain
| | - Luz García
- National Centre of Tropical Medicine-Institute of Health Carlos III, Madrid, Spain
| | - Ana Rodríguez-Galet
- National Centre of Tropical Medicine-Institute of Health Carlos III, Madrid, Spain.,HIV Molecular Epidemiology Laboratory, Ramón y Cajal-IRyCIS Hospital, Madrid, Spain
| | - Ramón Díaz-Regañón
- National Centre of Tropical Medicine-Institute of Health Carlos III, Madrid, Spain
| | - Rosario Galán
- National Centre of Tropical Medicine-Institute of Health Carlos III, Madrid, Spain
| | - Laura Cerrada-Gálvez
- National Centre of Tropical Medicine-Institute of Health Carlos III, Madrid, Spain
| | - Policarpo Ncogo
- State Foundation, Health, Childhood and Social Welfare FSP, Madrid, Spain
| | - Matilde Riloha
- Ministry of Health and Social Welfare-Malaria National Programme of Equatorial Guinea, Malabo, Equatorial Guinea
| | - Agustin Benito
- National Centre of Tropical Medicine-Institute of Health Carlos III, Madrid, Spain
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Owoloye A, Olufemi M, Idowu ET, Oyebola KM. Prevalence of potential mediators of artemisinin resistance in African isolates of Plasmodium falciparum. Malar J 2021; 20:451. [PMID: 34856982 PMCID: PMC8638531 DOI: 10.1186/s12936-021-03987-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 11/16/2021] [Indexed: 11/30/2022] Open
Abstract
Background The devastating public health impact of malaria has prompted the need for effective interventions. Malaria control gained traction after the introduction of artemisinin-based combination therapy (ACT). However, the emergence of artemisinin (ART) partial resistance in Southeast Asia and emerging reports of delayed parasite sensitivity to ACT in African parasites signal a gradual trend towards treatment failure. Monitoring the prevalence of mutations associated with artemisinin resistance in African populations is necessary to stop resistance in its tracks. Mutations in Plasmodium falciparum genes pfk13, pfcoronin and pfatpase6 have been linked with ART partial resistance. Methods Findings from published research articles on the prevalence of pfk13, pfcoronin and pfatpase6 polymorphisms in Africa were collated. PubMed, Embase and Google Scholar were searched for relevant articles reporting polymorphisms in these genes across Africa from 2014 to August 2021, for pfk13 and pfcoronin. For pfatpase6, relevant articles between 2003 and August 2021 were retrieved. Results Eighty-seven studies passed the inclusion criteria for this analysis and reported 742 single nucleotide polymorphisms in 37,864 P. falciparum isolates from 29 African countries. Five validated-pfk13 partial resistance markers were identified in Africa: R561H in Rwanda and Tanzania, M476I in Tanzania, F446I in Mali, C580Y in Ghana, and P553L in an Angolan isolate. In Tanzania, three (L263E, E431K, S769N) of the four mutations (L263E, E431K, A623E, S769N) in pfatpase6 gene associated with high in vitro IC50 were reported. pfcoronin polymorphisms were reported in Senegal, Gabon, Ghana, Kenya, and Congo, with P76S being the most prevalent mutation. Conclusions This meta-analysis provides an overview of the prevalence and widespread distribution of pfk13, pfcoronin and pfatpase6 mutations in Africa. Understanding the phenotypic consequences of these mutations can provide information on the efficacy status of artemisinin-based treatment of malaria across the continent. Graphical Abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03987-6.
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Affiliation(s)
- Afolabi Owoloye
- Genomic Research in Biomedicine Laboratory, Biochemistry and Nutrition Department, Nigerian Institute of Medical Research, Lagos, Nigeria.,Parasitology and Bioinformatics Unit, Department of Zoology, Faculty of Science, University of Lagos, Lagos, Nigeria
| | - Michael Olufemi
- Genomic Research in Biomedicine Laboratory, Biochemistry and Nutrition Department, Nigerian Institute of Medical Research, Lagos, Nigeria.,Parasitology and Bioinformatics Unit, Department of Zoology, Faculty of Science, University of Lagos, Lagos, Nigeria
| | - Emmanuel T Idowu
- Parasitology and Bioinformatics Unit, Department of Zoology, Faculty of Science, University of Lagos, Lagos, Nigeria
| | - Kolapo M Oyebola
- Genomic Research in Biomedicine Laboratory, Biochemistry and Nutrition Department, Nigerian Institute of Medical Research, Lagos, Nigeria. .,Parasitology and Bioinformatics Unit, Department of Zoology, Faculty of Science, University of Lagos, Lagos, Nigeria. .,Sickle Cell Branch, National Heart Lung and Blood Institute, US National Institutes of Health, Bethesda, MD, USA.
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Tang T, Xu Y, Cao L, Tian P, Shao J, Deng Y, Zhou H, Xiao B. Ten-Year Molecular Surveillance of Drug-Resistant Plasmodium spp. Isolated From the China-Myanmar Border. Front Cell Infect Microbiol 2021; 11:733788. [PMID: 34540721 PMCID: PMC8441003 DOI: 10.3389/fcimb.2021.733788] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 08/09/2021] [Indexed: 11/13/2022] Open
Abstract
Antimalarial drug resistance has emerged as a major threat to global malaria control efforts, particularly in the Greater Mekong Subregion (GMS). In this study, we analyzed the polymorphism and prevalence of molecular markers associated with resistance to first-line antimalarial drugs, such as artemisinin, chloroquine, and pyrimethamine, using blood samples collected from malaria patients in the China-Myanmar border region of the GMS from 2008 to 2017, including 225 cases of Plasmodium falciparum and 194 cases of Plasmodium vivax. In artemisinin resistance, only the C580Y mutation with low frequency was detected in pfk13, and no highly frequent stable mutation was found in pvk12. In chloroquine resistance, the frequency of K76T mutation in pfcrt was always high, and the frequency of double mutations in pvmdr1 of P. vivax has been steadily increasing every year. In pyrimidine resistance, pfdhfr and pvdhfr had relatively more complex mutant types associated with drug resistance sites, and the overall mutation rate was still high. Therefore, artemisinin-based combination therapies are still suitable for use as the first choice of antimalarial strategy in the China-Myanmar border region in the future.
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Affiliation(s)
- Tongke Tang
- Institut Pasteur of Shanghai, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Yanchun Xu
- Yunnan Institute of Parasitic Diseases Control, Pu'er, China
| | - Long Cao
- CAS Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Penghai Tian
- CAS Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Jiang Shao
- Institutional Center for Shared Technologies and Facilities of Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Yan Deng
- Yunnan Institute of Parasitic Diseases Control, Pu'er, China
| | - Hongning Zhou
- Yunnan Institute of Parasitic Diseases Control, Pu'er, China
| | - Bo Xiao
- CAS Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
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Yobi DM, Kayiba NK, Mvumbi DM, Boreux R, Kabututu PZ, Situakibanza HNT, Umesumbu SE, De Mol P, Speybroeck N, Mvumbi GL, Hayette MP. Assessment of Plasmodium falciparum anti-malarial drug resistance markers in pfk13-propeller, pfcrt and pfmdr1 genes in isolates from treatment failure patients in Democratic Republic of Congo, 2018-2019. Malar J 2021; 20:144. [PMID: 33706773 PMCID: PMC7953712 DOI: 10.1186/s12936-021-03636-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 02/09/2021] [Indexed: 11/14/2022] Open
Abstract
Background The national policy for malaria treatment of the Democratic Republic of Congo recommends two first-line artemisinin-based combinations for the treatment of uncomplicated malaria: artesunate-amodiaquine and artemether-lumefantrine. This study investigated the presence of markers associated with resistance to the current first-line artemisinin-based combination therapy (ACT) in isolates of Plasmodium falciparum from treatment failure patients in the Democratic Republic of Congo. Methods From November 2018 to November 2019, dried blood spots were taken from patients returning to health centres for fever within 28 days after an initial malaria treatment in six sentinel sites of the National Malaria Control Programme across Democratic Republic of Congo. The new episode of malaria was first detected by a rapid diagnostic test and then confirmed by a real-time PCR assay to define treatment failure. Fragments of interest in pfk13 and pfcrt genes were amplified by conventional PCR before sequencing and the Pfmdr1 gene copy number was determined by a TaqMan real-time PCR assay. Results Out of 474 enrolled patients, 364 (76.8%) were confirmed positive by PCR for a new episode of P. falciparum malaria, thus considered as treatment failure. Of the 325 P. falciparum isolates obtained from 364 P. falciparum-positive patients and successfully sequenced in the pfk13-propeller gene, 7 (2.2%) isolates carried non-synonymous mutations, among which 3 have been previously reported (N498I, N554K and A557S) and 4 had not yet been reported (F506L, E507V, D516E and G538S). Of the 335 isolates successfully sequenced in the pfcrt gene, 139 (41.5%) harboured the K76T mutation known to be associated with chloroquine resistance. The SVMNT haplotype associated with resistance to amodiaquine was not found. None of the isolates carried an increased copy number of the pfmdr1 gene among the 322 P. falciparum isolates successfully analysed. Conclusion No molecular markers currently known to be associated with resistance to the first-line ACT in use were detected in isolates of P. falciparum from treatment failure patients. Regular monitoring through in vivo drug efficacy and molecular studies must continue to ensure the effectiveness of malaria treatment in Democratic Republic of Congo.
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Affiliation(s)
- Doudou M Yobi
- Department of Basic Sciences, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo.
| | - Nadine K Kayiba
- School of Public Health and Research Institute of Health and Society, Catholic University of Louvain, 1200, Brussels, Belgium.,School of Public Health, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo.,Department of Public Health, Faculty of Medicine, University of Mbujimayi, Mbujimayi, Democratic Republic of Congo
| | - Dieudonné M Mvumbi
- Department of Basic Sciences, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Raphael Boreux
- Laboratory of Clinical Microbiology, University of Liège, 4000, Liège, Belgium
| | - Pius Z Kabututu
- Department of Basic Sciences, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Hippolyte N T Situakibanza
- Department of Internal Medicine, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Solange E Umesumbu
- National Malaria Control Programme, Kinshasa, Democratic Republic of Congo
| | - Patrick De Mol
- Laboratory of Clinical Microbiology, University of Liège, 4000, Liège, Belgium
| | - Niko Speybroeck
- School of Public Health and Research Institute of Health and Society, Catholic University of Louvain, 1200, Brussels, Belgium
| | - Georges L Mvumbi
- Department of Basic Sciences, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
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Molecular surveillance of pfcrt, pfmdr1 and pfk13-propeller mutations in Plasmodium falciparum isolates imported from Africa to China. Malar J 2021; 20:73. [PMID: 33549122 PMCID: PMC7866736 DOI: 10.1186/s12936-021-03613-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 01/28/2021] [Indexed: 11/30/2022] Open
Abstract
Background The emergence and spread of multidrug resistance poses a significant risk to malaria control and eradication goals in the world. There has been no indigenous malaria cases reported in China since 2017, and China is approaching national malaria elimination. Therefore, anti-malarial drug resistance surveillance and tracking the emergence and spread of imported drug-resistant malaria cases will be necessary in a post-elimination phase in China. Methods Dried blood spots were obtained from Plasmodium falciparum-infected cases returned from Africa to China between 2012 and 2015, prior to anti-malarial drug treatment. Whole DNA were extracted and known polymorphisms relating to drug resistance of pfcrt, pfmdr1 gene, and the propeller domain of pfk13 were evaluated by nested PCR and sequencing. The haplotypes and prevalence of these three genes were evaluated separately. Chi-squared test and Fisher's exact test were used to evaluate differences among the different sub-regions of Africa. A P value < 0.05 was used to evaluate differences with statistical significance. The maps were created using ArcGIS. Results A total of 731 P. falciparum isolates were sequenced at the pfcrt locus. The wild type CVMNK was the most prevalent haplotype with prevalence of 62.8% and 29.8% of the isolates showed the triple mutant haplotype CVIET. A total of 434 P. falciparum isolates were successfully sequenced and pfmdr1 allelic variants were observed in only codons 86, 184 and 1246. Twelve haplotypes were identified and the prevalence of the wild type pfmdr1 NYD was 44.1%. The single mutant pfmdr1 in codons 86 and 184 was predominant but the haplotype NYY with single mutation in codon 1246 was not observed. The double mutant haplotype YFD was common in Africa. About 1,357 isolates were successfully sequenced of pfk13-propeller domain, the wild type was found in 1,308 samples (96.4%) whereby 49 samples (3.6%) had mutation in pfk13. Of 49 samples with pfk13 mutations, 22 non-synonymous and 4 synonymous polymorphic sites were confirmed. The A578S was the most common mutation in pfk13-propeller domain and three mutations associated with artemisinin resistance (M476I, R539T, P553L) were identified in three isolates. Conclusion This study provides evidence that could give insight into potential issues with anti-malarial drug resistance to inform national drug policy in China in order to treat imported cases.
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Dafalla OM, Alzahrani M, Sahli A, Al Helal MA, Alhazmi MM, Noureldin EM, Mohamed WS, Hamid TB, Abdelhaleem AA, Hobani YA, Arif OA, Bokar IM, Hakami AM, Eisa ZM. Kelch 13-propeller polymorphisms in Plasmodium falciparum from Jazan region, southwest Saudi Arabia. Malar J 2020; 19:397. [PMID: 33168025 PMCID: PMC7653757 DOI: 10.1186/s12936-020-03467-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 10/27/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Artemisinin-based combination therapy (ACT) is recommended at the initial phase for treatment of Plasmodium falciparum, to reduce morbidity and mortality in all countries where malaria is endemic. Polymorphism in portions of P. falciparum gene encoding kelch (K13)-propeller domains is associated with delayed parasite clearance after ACT. Of about 124 different non-synonymous mutations, 46 have been identified in Southeast Asia (SEA), 62 in sub-Saharan Africa (SSA) and 16 in both the regions. This is the first study designed to analyse the prevalence of polymorphism in the P. falciparum k13-propeller domain in the Jazan region of southwest Saudi Arabia, where malaria is endemic. METHODS One-hundred and forty P. falciparum samples were collected from Jazan region of southwest Saudi Arabia at three different times: 20 samples in 2011, 40 samples in 2016 and 80 samples in 2020 after the implementation of ACT. Plasmodium falciparum kelch13 (k13) gene DNA was extracted, amplified, sequenced, and analysed using a basic local alignment search tool (BLAST). RESULTS This study obtained 51 non-synonymous (NS) mutations in three time groups, divided as follows: 6 single nucleotide polymorphisms (SNPs) '11.8%' in samples collected in 2011 only, 3 (5.9%) in 2011and 2016, 5 (9.8%) in 2011 and 2020, 5 (9.8%) in 2016 only, 8 (15.7%) in 2016 and 2020, 14 (27.5%) in 2020 and 10 (19.6%) in all the groups. The BLAST revealed that the 2011 isolates were genetically closer to African isolates (53.3%) than Asian ones (46.7%). Interestingly, this proportion changed completely in 2020, to become closer to Asian isolates (81.6%) than to African ones (18.4%). CONCLUSIONS Despite the diversity of the identified mutations in the k13-propeller gene, these data did not report widespread artemisinin-resistant polymorphisms in the Jazan region where these samples were collected. Such a process would be expected to increase frequencies of mutations associated with the resistance of ACT.
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Affiliation(s)
| | - Mohammed Alzahrani
- Zoonotic and Vector - Borne Diseases Ministry of Health, Riyadh, Saudi Arabia
| | - Ahmed Sahli
- Zoonotic and Vector - Borne Diseases Ministry of Health, Riyadh, Saudi Arabia
| | | | | | | | | | | | | | - Yahya Ali Hobani
- National Center for Diseases Prevention and Control, Jazan, Saudi Arabia
| | - Ommar Ali Arif
- National Center for Diseases Prevention and Control, Jazan, Saudi Arabia
| | | | | | - Zaki Manawar Eisa
- National Center for Diseases Prevention and Control, Jazan, Saudi Arabia
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Kayiba NK, Yobi DM, Tshibangu-Kabamba E, Tuan VP, Yamaoka Y, Devleesschauwer B, Mvumbi DM, Okitolonda Wemakoy E, De Mol P, Mvumbi GL, Hayette MP, Rosas-Aguirre A, Speybroeck N. Spatial and molecular mapping of Pfkelch13 gene polymorphism in Africa in the era of emerging Plasmodium falciparum resistance to artemisinin: a systematic review. THE LANCET. INFECTIOUS DISEASES 2020; 21:e82-e92. [PMID: 33125913 DOI: 10.1016/s1473-3099(20)30493-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 03/29/2020] [Accepted: 04/21/2020] [Indexed: 12/19/2022]
Abstract
The spread of Plasmodium falciparum isolates carrying mutations in the kelch13 (Pfkelch13) gene associated with artemisinin resistance (PfART-R) in southeast Asia threatens malaria control and elimination efforts. Emergence of PfART-R in Africa would result in a major public health problem. In this systematic review, we investigate the frequency and spatial distribution of Pfkelch13 mutants in Africa, including mutants linked to PfART-R in southeast Asia. Seven databases were searched (PubMed, Embase, Scopus, African Journal Online, African Index Medicus, Bioline, and Web of Science) for relevant articles about polymorphisms of the Pfkelch13 gene in Africa before January, 2019. Following PRISMA guidelines, 53 studies that sequenced the Pfkelch13 gene of 23 100 sample isolates in 41 sub-Saharan African countries were included. The Pfkelch13 sequence was highly polymorphic (292 alleles, including 255 in the Pfkelch13-propeller domain) but with mutations occurring at very low relative frequencies. Non-synonymous mutations were found in only 626 isolates (2·7%) from west, central, and east Africa. According to WHO, nine different mutations linked to PfART-R in southeast Asia (Phe446Ile, Cys469Tyr, Met476Ile, Arg515Lys, Ser522Cys, Pro553Leu, Val568Gly, Pro574Leu, and Ala675Val) were detected, mainly in east Africa. Several other Pfkelch13 mutations, such as those structurally similar to southeast Asia PfART-R mutations, were also identified, but their relevance for drug resistance is still unknown. This systematic review shows that Africa, thought to not have established PfART-R, reported resistance-related mutants in the past 5 years. Surveillance using PfART-R molecular markers can provide valuable decision-making information to sustain the effectiveness of artemisinin in Africa.
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Affiliation(s)
- Nadine K Kayiba
- Institute of Health and Society, Université catholique de Louvain, Brussels, Belgium; Department of Public Health, University of Mbujimayi, Mbujimayi, DR Congo; Department of Epidemiology and Biostatistics, University of Kinshasa, Kinshasa, DR Congo
| | - Doudou M Yobi
- Department of Basic Sciences, University of Kinshasa, Kinshasa, DR Congo
| | - Evariste Tshibangu-Kabamba
- Department of Basic Sciences, University of Mbujimayi, Mbujimayi, DR Congo; Department of Environmental and Preventive Medicine, Oita University, Yufu, Japan
| | - Vo P Tuan
- Department of Endoscopy, Cho Ray Hospital, Ho Chi Minh, Vietnam; Department of Environmental and Preventive Medicine, Oita University, Yufu, Japan
| | - Yoshio Yamaoka
- Department of Environmental and Preventive Medicine, Oita University, Yufu, Japan
| | - Brecht Devleesschauwer
- Department of Epidemiology and Public Health, Sciensano, Brussels, Belgium; Department of Veterinary Public Health and Food Safety, Ghent University, Merelbeke, Belgium
| | - Dieudonné M Mvumbi
- Department of Basic Sciences, University of Kinshasa, Kinshasa, DR Congo
| | | | - Patrick De Mol
- Department of Parasitology and Mycology, University Hospital of Liège, Liège, Belgium
| | - Georges L Mvumbi
- Department of Basic Sciences, University of Kinshasa, Kinshasa, DR Congo
| | - Marie-Pierre Hayette
- Department of Parasitology and Mycology, University Hospital of Liège, Liège, Belgium
| | - Angel Rosas-Aguirre
- Institute of Health and Society, Université catholique de Louvain, Brussels, Belgium
| | - Niko Speybroeck
- Institute of Health and Society, Université catholique de Louvain, Brussels, Belgium.
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Pacheco MA, Schneider KA, Cheng Q, Munde EO, Ndege C, Onyango C, Raballah E, Anyona SB, Ouma C, Perkins DJ, Escalante AA. Changes in the frequencies of Plasmodium falciparum dhps and dhfr drug-resistant mutations in children from Western Kenya from 2005 to 2018: the rise of Pfdhps S436H. Malar J 2020; 19:378. [PMID: 33092587 PMCID: PMC7583259 DOI: 10.1186/s12936-020-03454-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 10/18/2020] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Sulfadoxine-pyrimethamine (SP) is the only anti-malarial drug formulation approved for intermittent preventive treatment in pregnancy (IPTp). However, mutations in the Plasmodium falciparum dhfr (Pfdhfr) and dhps (Pfdhps) genes confer resistance to pyrimethamine and sulfadoxine, respectively. Here, the frequencies of SP resistance-associated mutations from 2005 to 2018 were compared in samples from Kenyan children with malaria residing in a holoendemic transmission region. METHODS Partial sequences of the Pfdhfr and Pfdhps genes were amplified and sequenced from samples collected in 2005 (n = 81), 2010 (n = 95), 2017 (n = 43), and 2018 (n = 55). The frequency of known mutations conferring resistance to pyrimethamine and sulfadoxine were estimated and compared. Since artemisinin-based combination therapy (ACT) is the current first-line treatment for malaria, the presence of mutations in the propeller domain of P. falciparum kelch13 gene (Pfk13) linked to ACT-delayed parasite clearance was studied in the 2017/18 samples. RESULTS Among other changes, the point mutation of Pfdhps S436H increased in frequency from undetectable in 2005 to 28% in 2017/18. Triple Pfdhfr mutant allele (CIRNI) increased in frequency from 84% in 2005 to 95% in 2017/18, while the frequency of Pfdhfr double mutant alleles declined (allele CICNI from 29% in 2005 to 6% in 2017/18, and CNRNI from 9% in 2005 to undetectable in 2010 and 2017/18). Thus, a multilocus Pfdhfr/Pfdhps genotype with six mutations (HGEAA/CIRNI), including Pfdhps S436H, increased in frequency from 2010 to 2017/18. Although none of the mutations associated with ACT-delayed parasite clearance was observed, the Pfk13 mutation A578S, the most widespread Pfk13 SNP found in Africa, was detected in low frequency (2.04%). CONCLUSIONS There were changes in SP resistance mutant allele frequencies, including an increase in the Pfdhps S436H. Although these patterns seem consistent with directional selection due to drug pressure, there is a lack of information to determine the actual cause of such changes. These results suggest incorporating molecular surveillance of Pfdhfr/Pfdhps mutations in the context of SP efficacy studies for intermittent preventive treatment in pregnancy (IPTp).
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Affiliation(s)
- M Andreína Pacheco
- Biology Department/Institute of Genomics and Evolutionary Medicine (iGEM), Temple University, Philadelphia, PA, USA
| | - Kristan A Schneider
- Department of Applied Computer and Biosciences, University of Applied Sciences Mittweida, Technikumplatz, Mittweida, Germany
| | - Qiuying Cheng
- Center for Global Health, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Elly O Munde
- University of New Mexico-Kenya Global Health Programs, Kisumu, Siaya, Kenya
- Department of Clinical Medicine, School of Health Sciences, Kirinyaga University, Kerugoya, Kenya
| | - Caroline Ndege
- University of New Mexico-Kenya Global Health Programs, Kisumu, Siaya, Kenya
- Department of Biomedical Sciences and Technology, Maseno University, Maseno, Kenya
| | - Clinton Onyango
- University of New Mexico-Kenya Global Health Programs, Kisumu, Siaya, Kenya
- Department of Biomedical Sciences and Technology, Maseno University, Maseno, Kenya
| | - Evans Raballah
- University of New Mexico-Kenya Global Health Programs, Kisumu, Siaya, Kenya
- Department of Medical Laboratory Sciences, School of Public Health, Biomedical Sciences and Technology, Masinde Muliro University of Science and Technology, Kakamega, Kenya
| | - Samuel B Anyona
- University of New Mexico-Kenya Global Health Programs, Kisumu, Siaya, Kenya
- Department of Medical Biochemistry, School of Medicine, Maseno University, Maseno, Kenya
| | - Collins Ouma
- University of New Mexico-Kenya Global Health Programs, Kisumu, Siaya, Kenya
- Department of Biomedical Sciences and Technology, Maseno University, Maseno, Kenya
| | - Douglas J Perkins
- Center for Global Health, University of New Mexico Health Sciences Center, Albuquerque, NM, USA.
- University of New Mexico-Kenya Global Health Programs, Kisumu, Siaya, Kenya.
| | - Ananias A Escalante
- Biology Department/Institute of Genomics and Evolutionary Medicine (iGEM), Temple University, Philadelphia, PA, USA.
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Khaemba EN, Ogwang C, Kinyanjui S, Muindi JM, Koske JK, Kimani D, Ngoi J, Mwacharo J, Shangala J, Njuguna P, Mutinda D, Nyatichi E, Peshu J, Mutinda B, Ndungu FM, Farnert A, Bashraheil MM, Bejon P, Kapulu MC. Comparing drug regimens for clearance of malaria parasites in asymptomatic adults using PCR in Kilifi County, Kenya: an open-label randomised controlled clinical trial (MalPaC). Wellcome Open Res 2020. [DOI: 10.12688/wellcomeopenres.15627.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Background: To restrict trial endpoints to infections acquired after vaccination in Phase IIb trials of candidate malaria vaccines, participants are treated with anti-malarial drugs to clear existing infections. Anti-malarial drugs with a long half-life may inhibit the acquisition of new infections. This study evaluated the effects of three anti-malarial drug regimens on the clearance of existing infections and acquisition of new infections. Methods: An open-label randomised controlled trial (MalPaC) was conducted between November 2013 and February 2014. Ninety adults were randomised 1:1:1 to receive one of three treatments: atovaquone/proguanil and artesunate (AP+AS); artesunate (AS); or sulphadoxine-pyrimethamine, artesunate, and primaquine (SP+AS+PQ). Parasite monitoring was determined over 84-day follow-up by assessing Plasmodium falciparum positivity by 18s qPCR, live and sexual stage parasites by RT-PCR, and recrudescence of infections by msp2 genotyping. Results: At enrolment, parasite prevalence by qPCR was 44% (40/90, day 0), which fell to 10% (9/90, day 16), then rose to almost the initial rates by day 84 (39%, 35/90). Individuals treated with AS and SP+AS+PQ were more likely to have higher qPCR positive rates compared to participants treated with AP+AS in the immediate post-treatment phase (days 16-28) (OR=7.7 [95%CI 4.6-12.8] p<0.0005 and OR=4.2 [95%CI 2.6-6.8] p<0.0005, respectively). In the immediate post-treatment phase, qPCR positivity was less likely associated with evidence of live parasites and gametocytaemia. Prevalence of “old”, “new” or “undetectable” infections did not differ significantly over time or drug regimen. However, participants on the AP+AS drug regimen were less likely to have parasite infection recrudescence compared to participants treated with AS and SP+AS+PQ. Conclusion: Falciparum DNA remained detectable by PCR post-treatment with incomplete parasite clearance regardless of drug regimen. Though AP+AS drug regimen may also have partially suppressed the acquisition of new infections during post-treatment follow-up. Trial registration: Pan African Clinical Trials Registry, 22nd of August 2013, PACTR201309000625311.
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Plasmodium falciparum Kelch Propeller Polymorphisms in Clinical Isolates from Ghana from 2007 to 2016. Antimicrob Agents Chemother 2019; 63:AAC.00802-19. [PMID: 31427297 DOI: 10.1128/aac.00802-19] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 08/07/2019] [Indexed: 11/20/2022] Open
Abstract
The continuous surveillance of polymorphisms in the kelch propeller domain of Plasmodium falciparum from Africa is important for the discovery of the actual markers of artemisinin resistance in the region. The information on the markers is crucial for control strategies involving chemotherapy and chemoprophylaxis for residents and nonimmune travelers to the country. Polymorphisms in the kelch propeller domain of Ghanaian malaria parasites from three different ecological zones at several time periods were assessed. A total of 854 archived samples (2007 to 2016) collected from uncomplicated malaria patients aged ≤9 years old from 10 sentinel sites were used. Eighty-four percent had wild-type sequences (PF3D7_1343700), while many of the mutants had mostly nonsynonymous mutations clustered around codons 404 to 650. Variants with different amino acid changes of the codons associated with artemisinin (ART) resistance validated markers were observed in Ghanaian isolates: frequencies for I543I, I543S, I543V, R561P, R561R, and C580V were 0.12% each and 0.6% for R539I. Mutations reported from African parasites, A578S (0.23%) and Q613L (0.23%), were also observed. Three persisting nonsynonymous (NS) mutations, N599Y (0.005%), K607E (0.004%), and V637G (0.004%), were observed in 3 of the 5 time periods nationally. The presence of variants of the validated markers of artemisinin resistance as well as persisting polymorphisms after 14 years of artemisinin-based combination therapy use argues for continuous surveillance of the markers. The molecular markers of artemisinin resistance and the observed variants will be monitored subsequently as part of ongoing surveillance of antimalarial drug efficacy/resistance studies in the country.
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The Diversity of the Plasmodium falciparum K13 Propeller Domain Did Not Increase after Implementation of Artemisinin-Based Combination Therapy in Uganda. Antimicrob Agents Chemother 2019; 63:AAC.01234-19. [PMID: 31358588 DOI: 10.1128/aac.01234-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 07/08/2019] [Indexed: 12/15/2022] Open
Abstract
Artemisinin-based combination therapies (ACTs) are the standard of care to treat uncomplicated falciparum malaria. However, resistance to artemisinins, defined as delayed parasite clearance after therapy, has emerged in Southeast Asia, and the spread of resistance to sub-Saharan Africa could have devastating consequences. Artemisinin resistance has been associated in Southeast Asia with multiple nonsynonymous single nucleotide polymorphisms (NS-SNPs) in the propeller domain of the gene encoding the Plasmodium falciparum K13 protein (K13PD). Some K13PD NS-SNPs have been seen in Africa, but the relevance of these mutations is unclear. To assess whether ACT use has selected for specific K13PD mutations, we compared the K13PD genetic diversity in clinical isolates collected before and after the implementation of ACT use from seven sites across Uganda. We detected K13PD NS-SNPs in 16 of 683 (2.3%) clinical isolates collected between 1999 and 2004 and in 26 of 716 (3.6%) isolates collected between 2012 and 2016 (P = 0.16), representing a total of 29 different polymorphisms at 27 codons. Individual NS-SNPs were usually detected only once, and none were found in more than 0.7% of the isolates. Three SNPs (C469F, P574L, and A675V) associated with delayed clearance in Southeast Asia were seen in samples collected between 2012 and 2016, each in a single isolate. No differences in diversity following implementation of ACT use were found at any of the seven sites, nor was there evidence of selective pressures acting on the locus. Our results suggest that selection by ACTs is not impacting on K13PD diversity in Uganda.
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Eboumbou Moukoko CE, Huang F, Nsango SE, Kojom Foko LP, Ebong SB, Epee Eboumbou P, Yan H, Sitchueng L, Garke B, Ayong L. K-13 propeller gene polymorphisms isolated between 2014 and 2017 from Cameroonian Plasmodium falciparum malaria patients. PLoS One 2019; 14:e0221895. [PMID: 31479501 PMCID: PMC6719859 DOI: 10.1371/journal.pone.0221895] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 08/16/2019] [Indexed: 12/23/2022] Open
Abstract
The emergence of artemisinin-resistant parasites since the late 2000s at the border of Cambodia and Thailand poses serious threats to malaria control globally, particularly in Africa which bears the highest malaria transmission burden. This study aimed to obtain reliable data on the current state of the kelch13 molecular marker for artemisinin resistance in Plasmodium falciparum in Cameroon. DNA was extracted from the dried blood spots collected from epidemiologically distinct endemic areas in the Center, Littoral and North regions of Cameroon. Nested PCR products from the Kelch13-propeller gene were sequenced and analyzed on an ABI 3730XL automatic sequencer. Of 219 dried blood spots, 175 were sequenced successfully. We identified six K13 mutations in 2.9% (5/175) of samples, including 2 non-synonymous, the V589I allele had been reported in Africa already and one new allele E612K had not been reported yet. These two non-synonymous mutations were uniquely found in parasites from the Littoral region. One sample showed two synonymous mutations within the kelch13 gene. We also observed two infected samples with mixed K13 mutant and K13 wild-type infection. Taken together, our data suggested the circulation of the non-synonymous K13 mutations in Cameroon. Albeit no mutations known to be associated with parasite clearance delays in the study population, there is need for continuous surveillance for earlier detection of resistance as long as ACTs are used and scaled up in the community.
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Affiliation(s)
- Carole Else Eboumbou Moukoko
- Biological Sciences Department, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, Cameroon
- Malaria Research Unit, Centre Pasteur Cameroon, Yaoundé, Cameroon
- * E-mail: , (CEEM); (FH)
| | - Fang Huang
- Malarial Department, National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, China
- * E-mail: , (CEEM); (FH)
| | - Sandrine Eveline Nsango
- Biological Sciences Department, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, Cameroon
- Malaria Research Unit, Centre Pasteur Cameroon, Yaoundé, Cameroon
| | - Loic Pradel Kojom Foko
- Parasitology and Entomology Research Unit, Department of Animal Organisms, Faculty of Science, University of Douala, Douala, Cameroon
| | - Serge Bruno Ebong
- Animal Organisms Biology and Physiology Department, Faculty of Sciences, University of Douala, Douala, Cameroon
| | | | - He Yan
- Malarial Department, National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, China
| | - Livia Sitchueng
- Malaria Research Unit, Centre Pasteur Cameroon, Yaoundé, Cameroon
| | - Bouba Garke
- Centre Pasteur Cameroon, Garoua Center, Yaoundé, Cameroon
| | - Lawrence Ayong
- Malaria Research Unit, Centre Pasteur Cameroon, Yaoundé, Cameroon
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19
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Evolution and Genetic Diversity of the k13 Gene Associated with Artemisinin Delayed Parasite Clearance in Plasmodium falciparum. Antimicrob Agents Chemother 2019; 63:AAC.02550-18. [PMID: 31085516 DOI: 10.1128/aac.02550-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 04/28/2019] [Indexed: 01/19/2023] Open
Abstract
Mutations in the Plasmodium falciparum k13 (Pfk13) gene are linked to delayed parasite clearance in response to artemisinin-based combination therapies (ACTs) in Southeast Asia. To explore the evolutionary rate and constraints acting on this gene, k13 orthologs from species sharing a recent common ancestor with P. falciparum and Plasmodium vivax were analyzed. These comparative studies were followed by genetic polymorphism analyses within P. falciparum using 982 complete Pfk13 sequences from public databases and new data obtained by next-generation sequencing from African and Haitian isolates. Although k13 orthologs evolve at heterogeneous rates, the gene was conserved across the genus, with only synonymous substitutions being found at residues where mutations linked to the delayed parasite clearance phenotype have been reported. This suggests that those residues were under constraint from undergoing nonsynonymous changes during evolution of the genus. No fixed nonsynonymous differences were found between Pfk13 and its orthologs in closely related species found in African apes. This indicates that all nonsynonymous substitutions currently found in Pfk13 are younger than the time of divergence between P. falciparum and its closely related species. At the population level, no mutations linked to delayed parasite clearance were found in our samples from Africa and Haiti. However, there is a high number of single Pfk13 mutations segregating in P. falciparum populations, and two predominant alleles are distributed worldwide. This pattern is discussed in terms of how changes in the efficacy of natural selection, affected by population expansion, may have allowed for the emergence of mutations tolerant to ACTs.
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20
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Coppée R, Jeffares DC, Miteva MA, Sabbagh A, Clain J. Comparative structural and evolutionary analyses predict functional sites in the artemisinin resistance malaria protein K13. Sci Rep 2019; 9:10675. [PMID: 31337835 PMCID: PMC6650413 DOI: 10.1038/s41598-019-47034-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 07/03/2019] [Indexed: 01/31/2023] Open
Abstract
Numerous mutations in the Plasmodium falciparum Kelch13 (K13) protein confer resistance to artemisinin derivatives, the current front-line antimalarial drugs. K13 is an essential protein that contains BTB and Kelch-repeat propeller (KREP) domains usually found in E3 ubiquitin ligase complexes that target substrate protein(s) for ubiquitin-dependent degradation. K13 is thought to bind substrate proteins, but its functional/interaction sites and the structural alterations associated with artemisinin resistance mutations remain unknown. Here, we screened for the most evolutionarily conserved sites in the protein structure of K13 as indicators of structural and/or functional constraints. We inferred structure-dependent substitution rates at each amino acid site of the highly conserved K13 protein during the evolution of Apicomplexa parasites. We found two solvent-exposed patches of extraordinarily conserved sites likely involved in protein-protein interactions, one in BTB and the other one in KREP. The conserved patch in K13 KREP overlaps with a shallow pocket that displays a differential electrostatic surface potential, relative to neighboring sites, and that is rich in serine and arginine residues. Comparative structural and evolutionary analyses revealed that these properties were also found in the functionally-validated shallow pocket of other KREPs including that of the cancer-related KEAP1 protein. Finally, molecular dynamics simulations carried out on PfK13 R539T and C580Y artemisinin resistance mutant structures revealed some local structural destabilization of KREP but not in its shallow pocket. These findings open new avenues of research on one of the most enigmatic malaria proteins with the utmost clinical importance.
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Affiliation(s)
- Romain Coppée
- Université de Paris, UMR 261 MERIT, IRD, F-75006 Paris, France
| | - Daniel C Jeffares
- Department of Biology and York Biomedical Research Institute, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Maria A Miteva
- Université de Paris, Inserm U1268 MCTR, CiTCom UMR 8038 CNRS, Paris, France
| | - Audrey Sabbagh
- Université de Paris, UMR 261 MERIT, IRD, F-75006 Paris, France.
| | - Jérôme Clain
- Université de Paris, UMR 261 MERIT, IRD, F-75006 Paris, France. .,Centre National de Référence du Paludisme, Hôpital Bichat-Claude Bernard, Assistance Publique des Hôpitaux de Paris, F-75018 Paris, France.
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21
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Polymorphisms in Plasmodium falciparum Kelch 13 and P. vivax Kelch 12 Genes in Parasites Collected from Three South Pacific Countries Prior to Extensive Exposure to Artemisinin Combination Therapies. Antimicrob Agents Chemother 2019; 63:AAC.00536-19. [PMID: 31036683 DOI: 10.1128/aac.00536-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 04/22/2019] [Indexed: 11/20/2022] Open
Abstract
The South Pacific countries Solomon Islands, Vanuatu, and Papua New Guinea (PNG) adopted artemisinin-based combination therapies (ACTs) in 2008. We examined Kelch 13 and Kelch 12 genes in parasites originating from these countries before or at ACT introduction. Four Kelch 13 and two Kelch 12 novel sequence polymorphisms, not associated with artemisinin resistance, were observed in parasites from Solomon Islands and Vanuatu. No polymorphisms were observed in PNG parasites. The findings provide useful baseline information.
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22
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Nderu D, Kimani F, Karanja E, Thiong'o K, Akinyi M, Too E, Chege W, Nambati E, Wangai LN, Meyer CG, Velavan TP. Genetic diversity and population structure of Plasmodium falciparum in Kenyan-Ugandan border areas. Trop Med Int Health 2019; 24:647-656. [PMID: 30816614 DOI: 10.1111/tmi.13223] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Kenya has, in the last decade, made tremendous progress in the fight against malaria. Nevertheless, continued surveillance of the genetic diversity and population structure of Plasmodium falciparum is required to refine malaria control and to adapt and improve elimination strategies. Twelve neutral microsatellite loci were genotyped in 201 P. falciparum isolates obtained from the Kenyan-Ugandan border (Busia) and from two inland malaria-endemic sites situated in western (Nyando) and coastal (Msambweni) Kenya. Analyses were done to assess the genetic diversity (allelic richness and expected heterozygosity, [He ]), multilocus linkage disequilibrium ( I S A ) and population structure. A similarly high degree of genetic diversity was observed among the three parasite populations surveyed (mean He = 0.76; P > 0.05). Except in Msambweni, random association of microsatellite loci was observed, indicating high parasite out-breeding. Low to moderate genetic structure (FST = 0.022-0.076; P < 0.0001) was observed with only 5% variance in allele frequencies observed among the populations. This study shows that the genetic diversity of P. falciparum populations at the Kenyan-Ugandan border is comparable to the parasite populations from inland Kenya. In addition, high genetic diversity, panmixia and weak population structure in this study highlight the fitness of Kenyan P. falciparum populations to successfully withstand malaria control interventions.
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Affiliation(s)
- David Nderu
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.,School of Health Sciences, Kirinyaga University, Kerugoya, Kenya
| | - Francis Kimani
- Center for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - Evaline Karanja
- Department of Biochemistry and Biotechnology, School of Biological and Life Sciences, Technical University of Kenya, Nairobi, Kenya
| | - Kelvin Thiong'o
- Center for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - Maureen Akinyi
- Center for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - Edwin Too
- Center for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - William Chege
- Center for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - Eva Nambati
- Center for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - Laura N Wangai
- School of Health Sciences, Kirinyaga University, Kerugoya, Kenya
| | - Christian G Meyer
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.,Vietnamese-German Centre for Medical Research, Hanoi, Vietnam.,Faculty of Medicine, Duy Tan University, Da Nang, Vietnam
| | - Thirumalaisamy P Velavan
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.,Vietnamese-German Centre for Medical Research, Hanoi, Vietnam.,Faculty of Medicine, Duy Tan University, Da Nang, Vietnam.,Fondation Congolaise pour la Recherche Médicale, Brazzaville, Republic of Congo
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23
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Thillainayagam M, Malathi K, Anbarasu A, Singh H, Bahadur R, Ramaiah S. Insights on inhibition of Plasmodium falciparum plasmepsin I by novel epoxyazadiradione derivatives – molecular docking and comparative molecular field analysis. J Biomol Struct Dyn 2018. [DOI: 10.1080/07391102.2018.1510342 pmid: 30092746] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Mahalakshmi Thillainayagam
- Medical & Biological Computing Laboratory, School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
| | - Kullappan Malathi
- Medical & Biological Computing Laboratory, School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
| | - Anand Anbarasu
- Medical & Biological Computing Laboratory, School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
| | | | - Renu Bahadur
- Indian Council for Medical Research, New Delhi, India
| | - Sudha Ramaiah
- Medical & Biological Computing Laboratory, School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
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24
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Thillainayagam M, Malathi K, Anbarasu A, Singh H, Bahadur R, Ramaiah S. Insights on inhibition of Plasmodium falciparum plasmepsin I by novel epoxyazadiradione derivatives – molecular docking and comparative molecular field analysis. J Biomol Struct Dyn 2018; 37:3168-3182. [DOI: 10.1080/07391102.2018.1510342] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Mahalakshmi Thillainayagam
- Medical & Biological Computing Laboratory, School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
| | - Kullappan Malathi
- Medical & Biological Computing Laboratory, School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
| | - Anand Anbarasu
- Medical & Biological Computing Laboratory, School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
| | | | - Renu Bahadur
- Indian Council for Medical Research, New Delhi, India
| | - Sudha Ramaiah
- Medical & Biological Computing Laboratory, School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
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