Dataset Information

Frequencies distribution of dihydrofolate reductase and dihydropteroate synthetase mutant alleles associated with sulfadoxine-pyrimethamine resistance in Plasmodium falciparum population from Hadhramout Governorate, Yemen.

ABSTRACT: Malaria in Yemen is mainly caused by Plasmodium falciparum and 25% of the population is at high risk. Sulfadoxine-pyrimethamine (SP) had been used as monotherapy against P. falciparum. Emergence of chloroquine resistance led to the shift in anti-malarial treatment policy in Yemen to artemisinin-based combination therapy, that is artesunate (AS) plus SP as first-line therapy for uncomplicated malaria and artemether-lumefantrine as second-line treatment. This study aimed to screen mutations in the dihydrofolate reductase (dhfr) and dihydropteroate synthetase (dhps) genes associated with SP resistance among P. falciparum population in Hadhramout governorate, Yemen.Genomic DNA was extracted from dried blood spots of 137 P. falciparum isolates collected from a community-based study. DNA was amplified using nested polymerase chain reaction (PCR) and subsequently sequenced for Pfdhfr and Pfdhps genes. Sequences were analysed for mutations in Pfdhfr gene codons 51, 59, 108, and 164 and in Pfdhps gene codons 436, 437, and 540.A total of 128 and 114 P. falciparum isolates were successfully sequenced for Pfdhfr and Pfdhps genes, respectively. Each Pfdhfr mutant allele (I51 and N108) in P. falciparum population had a frequency of 84%. Pfdhfr R59 mutant allele was detected in one isolate. Mutation at codon 437 (G437) in the Pfdhps gene was detected in 44.7% of falciparum malaria isolates. Frequencies of Pfdhfr double mutant genotype (I51C59N108I164) and Pfdhfr/Pfdhps triple mutant genotype (I51C59N108I164-S436G437K540) were 82.8 and 39.3%, respectively. One isolate harboured Pfdhfr triple mutant genotype (I51, R59, N108, I164) and Pfdhfr/Pfdhps quadruple mutant genotype (I51R59N108I164-S436G437K540).High frequencies of Pfdhfr and Pfdhps mutant alleles and genotypes in P. falciparum population in Hadhramout, Yemen, highlight the risk of developing resistance for SP, the partner drug of AS, which subsequently will expose the parasite to AS monotherapy increasing then the potential of the emergence of AS resistance. Study findings necessitate the continuous monitoring of the efficacy of the national anti-malarial drugs policy in Yemen. In addition, monitoring SP efficacy using molecular markers that has shown to be a practical and informative method for monitoring the partner drug of AS.

SUBMITTER: Bamaga OA

PROVIDER: S-EPMC4688959 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Frequencies distribution of dihydrofolate reductase and dihydropteroate synthetase mutant alleles associated with sulfadoxine-pyrimethamine resistance in Plasmodium falciparum population from Hadhramout Governorate, Yemen.

Bamaga Omar A A OA Mahdy Mohammed A K MA Lim Yvonne A L YA

Malaria journal 20151222

<h4>Background</h4>Malaria in Yemen is mainly caused by Plasmodium falciparum and 25% of the population is at high risk. Sulfadoxine-pyrimethamine (SP) had been used as monotherapy against P. falciparum. Emergence of chloroquine resistance led to the shift in anti-malarial treatment policy in Yemen to artemisinin-based combination therapy, that is artesunate (AS) plus SP as first-line therapy for uncomplicated malaria and artemether-lumefantrine as second-line treatment. This study aimed to scre ...[more]

PMID: 26693691

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Project description:Plasmodium falciparum parasites resistant to antimalarial treatments have hindered malaria disease control. Sulfadoxine-pyrimethamine (SP) was used globally as a first-line treatment for malaria after wide-spread resistance to chloroquine emerged and, although replaced by artemisinin combinations, is currently used as intermittent preventive treatment of malaria in pregnancy and in young children as part of seasonal malaria chemoprophylaxis in sub-Saharan Africa. The emergence of SP-resistant parasites has been predominantly driven by cumulative build-up of mutations in the dihydrofolate reductase (pfdhfr) and dihydropteroate synthetase (pfdhps) genes, but additional amplifications in the folate pathway rate-limiting pfgch1 gene and promoter, have recently been described. However, the genetic make-up and prevalence of those amplifications is not fully understood. We analyse the whole genome sequence data of 4,134 P. falciparum isolates across 29 malaria endemic countries, and reveal that the pfgch1 gene and promoter amplifications have at least ten different forms, occurring collectively in 23% and 34% in Southeast Asian and African isolates, respectively. Amplifications are more likely to be present in isolates with a greater accumulation of pfdhfr and pfdhps substitutions (median of 1 additional mutations; P<0.00001), and there was evidence that the frequency of pfgch1 variants may be increasing in some African populations, presumably under the pressure of SP for chemoprophylaxis and anti-folate containing antibiotics used for the treatment of bacterial infections. The selection of P. falciparum with pfgch1 amplifications may enhance the fitness of parasites with pfdhfr and pfdhps substitutions, potentially threatening the efficacy of this regimen for prevention of malaria in vulnerable groups. Our work describes new pfgch1 amplifications that can be used to inform the surveillance of SP drug resistance, its prophylactic use, and future experimental work to understand functional mechanisms.

Project description:Malaria caused by Plasmodium falciparum infects roughly 30,000 individuals in Haiti each year. Haiti has used chloroquine (CQ) as a first-line treatment for malaria for many years and as a result there are concerns that malaria parasites may develop resistance to CQ over time. Therefore it is important to prepare for alternative malaria treatment options should CQ resistance develop. In many other malaria-endemic regions, antifolates, particularly pyrimethamine (PYR) and sulphadoxine (SDX) treatment combination (SP), have been used as an alternative when CQ resistance has developed. This study evaluated mutations in the dihydrofolate reductase (dhfr) and dihydropteroate synthetase (dhps) genes that confer PYR and SDX resistance, respectively, in P. falciparum to provide baseline data in Haiti. This study is the first comprehensive study to examine PYR and SDX resistance genotypes in P. falciparum in Haiti.DNA was extracted from dried blood spots and genotyped for PYR and SDX resistance mutations in P. falciparum using PCR and DNA sequencing methods. Sixty-one samples were genotyped for PYR resistance in codons 51, 59, 108 and 164 of the dhfr gene and 58 samples were genotyped for SDX resistance codons 436, 437, 540 of the dhps gene in P. falciparum.Thirty-three percent (20/61) of the samples carried a mutation at codon 108 (S108N) of the dhfr gene. No mutations in dhfr at codons 51, 59, 164 were observed in any of the samples. In addition, no mutations were observed in dhps at the three codons (436, 437, 540) examined. No significant difference was observed between samples collected in urban vs rural sites (Welch's T-test p-value = 0.53 and permutations p-value = 0.59).This study has shown the presence of the S108N mutation in P. falciparum that confers low-level PYR resistance in Haiti. However, the absence of SDX resistance mutations suggests that SP resistance may not be present in Haiti. These results have important implications for ongoing discussions on alternative malaria treatment options in Haiti.

Project description:With the spread of chloroquine (CQ)-resistant malaria in India, sulfadoxine-pyrimethamine (SP) alone or in combination with artesunate is used as an alternative antimalarial drug. Due to continuous drug pressure, the Plasmodium falciparum parasite is exhibiting resistance to antifolates because of mutations in candidate genes dihydrofolate reductase (dhfr) and dihydropteroate synthetase (dhps). Our earlier study on flanking microsatellite markers of dhfr mutant alleles from India had shown a single origin of the pyrimethamine resistance and some minor haplotypes which shared haplotypes with Southeast Asian (Thailand) strains. In the present study, we have analyzed 193 of these Indian P. falciparum isolates for 15 microsatellite loci around dhps to investigate the genetic lineages of the mutant dhps alleles in different parts of the country. Eighty-one of these samples had mutant dhps alleles, of which 62 were from Andaman and Nicobar Islands and the remaining 19 were from mainland India. Of 112 isolates with a wild-type dhps allele, 109 were from mainland India and only 3 were from Andaman and Nicobar Islands. Consistent with the model of selection, the mean expected heterozygosity (H(e)) around mutant dhps alleles (H(e) = 0.55; n = 81) associated with sulfadoxine resistance was lower (P ≤ 0.05) than the mean H(e) around the wild-type dhps allele (H(e) = 0.80; n = 112). There was more genetic diversity in flanking microsatellites of dhps than dhfr among these isolates, which confirms the assertion that dhps mutations are at a very early stage of fixation in the parasite population. Microsatellite haplotypes around various mutant dhps alleles suggest that the resistant dhps alleles have multiple independent origins in India, especially in Andaman and Nicobar Islands. Determining the genetic lineages of the resistant dhps alleles on Andaman and Nicobar Islands and mainland India is significant, given the role of Asia in the intercontinental spread of chloroquine- and pyrimethamine-resistant parasites in the past.

Project description:BackgroundSulfadoxine-pyrimethamine was a common first line drug therapy to treat uncomplicated falciparum malaria, but increasing therapeutic failures associated with the development of significant levels of resistance worldwide has prompted change to alternative treatment regimes in many national malaria control programs. METHODOLOGY AND FINDING: We conducted an in vivo therapeutic efficacy trial of sulfadoxine-pyrimethamine at two locations in the Peruvian Amazon enrolling 99 patients of which, 86 patients completed the protocol specified 28 day follow up. Our objective was to correlate the presence of polymorphisms in P. falciparum dihydrofolate reductase and dihydropteroate synthase to in vitro parasite susceptibility to sulfadoxine and pyrimethamine and to in vivo treatment outcomes. Inhibitory concentration 50 values of isolates increased with numbers of mutations (single [108N], sextuplet [BR/51I/108N/164L and 437G/581G]) and septuplet (BR/51I/108N/164L and 437G/540E/581G) with geometric means of 76 nM (35-166 nM), 582 nM (49-6890- nM) and 4909 (3575-6741 nM) nM for sulfadoxine and 33 nM (22-51 nM), 81 nM (19-345 nM), and 215 nM (176-262 nM) for pyrimethamine. A single mutation present in the isolate obtained at the time of enrollment from either dihydrofolate reductase (164L) or dihydropteroate synthase (540E) predicted treatment failure as well as any other single gene alone or in combination. Patients with the dihydrofolate reductase 164L mutation were 3.6 times as likely to be treatment failures [failures 85.4% (164L) vs 23.7% (I164); relative risk = 3.61; 95% CI: 2.14 - 6.64] while patients with the dihydropteroate synthase 540E were 2.6 times as likely to fail treatment (96.7% (540E) vs 37.5% (K540); relative risk = 2.58; 95% CI: 1.88 - 3.73). Patients with both dihydrofolate reductase 164L and dihydropteroate synthase 540E mutations were 4.1 times as likely to be treatment failures [96.7% vs 23.7%; RR = 4.08; 95% CI: 2.45 - 7.46] compared to patients having both wild forms (I164 and K540).ConclusionsIn this part of the Amazon basin, it may be possible to predict treatment failure with sulfadoxine-pyrimethamine equally well by determination of either of the single mutations dihydrofolate reductase 164L or dihydropteroate synthase 540E.Trial registrationClinicalTrials.gov NCT00951106.

Dataset Information

Frequencies distribution of dihydrofolate reductase and dihydropteroate synthetase mutant alleles associated with sulfadoxine-pyrimethamine resistance in Plasmodium falciparum population from Hadhramout Governorate, Yemen.

Publications

Frequencies distribution of dihydrofolate reductase and dihydropteroate synthetase mutant alleles associated with sulfadoxine-pyrimethamine resistance in Plasmodium falciparum population from Hadhramout Governorate, Yemen.

Similar Datasets

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