Dataset Information

Plasmodium vivax resistance to chloroquine in Madagascar: clinical efficacy and polymorphisms in pvmdr1 and pvcrt-o genes.

ABSTRACT: No data were available concerning Plasmodium vivax resistance to chloroquine (CQ) in Madagascar. We investigated the therapeutic efficacy of CQ in P. vivax malaria, the prevalence of mutations in the pvcrt-o and pvmdr1 genes before treatment, and the association between mutant parasites and the clinical response of the patients to CQ treatment. Clinical isolates were collected at six sentinel sites located in the three epidemiological strata for malaria throughout Madagascar in 2006. Patients were enrolled, treated, and followed up according to the WHO 2001 guidelines for P. vivax infections. Sequencing was used to analyze polymorphisms of the pvcrt-o (exons 1 to 6) and pvmdr1 genes. The treatment failure rate, after adjustment for genotyping, was estimated at 5.1% for the 105 patients included, ranging from zero in the South to 14.8% in the foothills of the Central Highlands. All samples were wild type for pvcrt-o but mutant for the pvmdr1 gene. Ten nonsynonymous mutations were found in the pvmdr1 gene, including five new mutations, four of which were present at low frequencies (1.3% to 7.5%) while the S513R mutation was present at a much higher frequency (96.3%). The other five mutations, including Y976F, had been described before and had frequencies of 97.8% to 100%. Our findings suggest that CQ-resistant P. vivax isolates are present in Madagascar, particularly in the foothills of the Central Highlands. The 976Y pvmdr1 mutation was found not to be useful for monitoring CQ resistance. Further efforts are required to develop suitable tools for monitoring drug resistance in P. vivax malaria.

SUBMITTER: Barnadas C

PROVIDER: S-EPMC2592859 | biostudies-literature | 2008 Dec

REPOSITORIES: biostudies-literature

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Plasmodium vivax resistance to chloroquine in Madagascar: clinical efficacy and polymorphisms in pvmdr1 and pvcrt-o genes.

Barnadas Céline C Ratsimbasoa Arsène A Tichit Magali M Bouchier Christiane C Jahevitra Martial M Picot Stéphane S Ménard Didier D

Antimicrobial agents and chemotherapy 20080922 12

No data were available concerning Plasmodium vivax resistance to chloroquine (CQ) in Madagascar. We investigated the therapeutic efficacy of CQ in P. vivax malaria, the prevalence of mutations in the pvcrt-o and pvmdr1 genes before treatment, and the association between mutant parasites and the clinical response of the patients to CQ treatment. Clinical isolates were collected at six sentinel sites located in the three epidemiological strata for malaria throughout Madagascar in 2006. Patients we ...[more]

PMID: 18809933

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Project description:BACKGROUND: There are increasing reports of severe clinical cases exclusively associated with Plasmodium vivax infections. Notably, this severity has been recently suggested to be associated with chloroquine resistance. PATIENTS: Two different patients presented at the Hospital Clinic in Barcelona with P. vivax malaria episodes. One patient had severe symptoms and the other mild symptoms. Both patients traveled through the Brazilian Amazon (Manaus) in 2007. For both patients the current diagnosis of malaria was the first. Two other patients with mild symptoms presented to the "Centro de Pesquisa em Medicina Tropical", also in the Brazilian Amazon (Rondônia) in 2000. METHODS: To exclude the possibility that the patient's severe symptoms were due to Plasmodium falciparum, a nested PCR was performed. A magnetic method was used to purify P. vivax free of human leukocytes. Quantitative real-time PCR was performed to compare the transcript levels of two main transporters likely to be involved in chloroquine resistance in P. vivax, namely the P. vivax chloroquine resistance transporter, pvcrt-o, and the P. vivax multidrug resistance transporter, pvmdr 1. RESULTS: Results demonstrated that the severe clinical symptoms were exclusively due to P. vivax. The patient presented acute respiratory conditions requiring admission to the intensive care unit. The magnetic method showed highly purified infected-reticulocytes with mature stages. In addition, it was found that parasites obtained from the severe patient had up to 2.9-fold increase in pvmdr1 levels and up to 21.9-fold increase in pvcrt-o levels compared to expression levels of parasites from the other patients with mild symptoms. CONCLUSION: This is the first clinical case of severe disease exclusively associated with vivax malaria in Spain. Moreover, these findings suggest that clinical severity could be associated with increased expression levels of parasite genes likely involved in chloroquine resistance. It is necessary to further explore the potential of pvmdr1 and particularly pvcrt-o expression levels as molecular markers of severe disease in P. vivax.

Project description:BackgroundVivax malaria is an important public health problem in the Greater Mekong Subregion (GMS), including the China-Myanmar border. Previous studies have found that Plasmodium vivax has decreased sensitivity to antimalarial drugs in some areas of the GMS, but the sensitivity of P. vivax to antimalarial drugs is unclear in the China-Myanmar border. Here, we investigate the drug sensitivity profile and genetic variations for two drug resistance related genes in P. vivax isolates to provide baseline information for future drug studies in the China-Myanmar border.Methodology/principal findingsA total of 64 P. vivax clinical isolates collected from the China-Myanmar border area were assessed for ex vivo susceptibility to eight antimalarial drugs by the schizont maturation assay. The medians of IC50 (half-maximum inhibitory concentrations) for chloroquine, mefloquine, pyronaridine, piperaquine, quinine, artesunate, artemether, dihydroartemisinin were 84.2 nM, 34.9 nM, 4.0 nM, 22.3 nM, 41.4 nM, 2.8 nM, 2.1 nM and 2.0 nM, respectively. Twelve P. vivax clinical isolates were found over the cut-off IC50 value (220 nM) for chloroquine resistance. In addition, sequence polymorphisms in pvmdr1 (P. vivax multidrug resistance-1), pvcrt-o (P. vivax chloroquine resistance transporter-o), and difference in pvmdr1 copy number were studied. Sequencing of the pvmdr1 gene in 52 samples identified 12 amino acid substitutions, among which two (G698S and T958M) were fixed, M908L were present in 98.1% of the isolates, while Y976F and F1076L were present in 3.8% and 78.8% of the isolates, respectively. Amplification of the pvmdr1 gene was only detected in 4.8% of the samples. Sequencing of the pvcrt-o in 59 parasite isolates identified a single lysine insertion at position 10 in 32.2% of the isolates. The pvmdr1 M908L substitutions in pvmdr1 in our samples was associated with reduced sensitivity to chloroquine, mefloquine, pyronaridine, piperaquine, quinine, artesunate and dihydroartemisinin.ConclusionsOur findings depict a drug sensitivity profile and genetic variations of the P. vivax isolates from the China-Myanmar border area, and suggest possible emergence of chloroquine resistant P. vivax isolates in the region, which demands further efforts for resistance monitoring and mechanism studies.

Project description:BackgroundThe efficacy of chloroquine treatment for vivax malaria has been rarely evaluated due to a lack of an appropriate testing method. The objective of this study was to conduct molecular monitoring of chloroquine resistance in Plasmodium vivax strains from vivax malaria patients in Yunnan Province, focusing on the analysis of polymorphism in the P. vivax chloroquine resistance transporter protein orthologous gene (pvcrt-o).MethodsIn accordance with the principles of a cohort study, blood samples were collected from malaria cases diagnosed with a P. vivax mono-infection in Yunnan Province from 2020 to 2022. Segmental PCR was used to amplify the whole pvcrt-o gene in the blood samples and their products were subsequently sequenced. The sequencing data were arranged to obtain the full coding DNA sequence (CDS) as well as the gene's promoter region sequences. The CDSs were aligned with the reference sequence (XM_001613407.1) of the P. vivax SalI isolate to identify the mutant loci.ResultsFrom a total of 375 blood samples taken from vivax malaria cases, 272 both whole gene CDSs (1272-1275 bp) and promoter DNA sequences (707 bp) of pvcrt-o gene were obtained. Among the whole CDSs, there were 7 single nucleotide polymorphic sites in which c.7 A>G was the minor allele frequency (MAF) site with 4.4% (12/272) detection rate. The mutation detection rate showed a significant decrease from 9.8% (10/102) in 2020 to 1.1% (1/92) in 2021 and 1.3% (1/78) in 2022, indicating statistical significance (χ2 = 11.256, P < 0.05). Among the identified 12 haplotypes, the majority of which were wild type (75.7%; 206/272). These four mutant haplotypes (Hap_3, Hap_5, Hap_9, and Hap_10) were classified as "K10 insertion type" and accounted for 12.1% (33/272). The detection rate of Hap_3 increased from 1.0% (1/102) in 2020 to 13.0% (12/92) in 2021 and 14.1% (11/78) in 2022, indicating statistical significance. A total of 23.8% (65/272) of the samples exhibited 14 bp (bp) deletions in the promoter region, occurring most frequently in the wild type haplotype (Hap_1) samples at a rate of 28.6% (59/206).ConclusionsIn recent years in Yunnan Province, a notable proportion of vivax malaria patients are infected by P. vivax strains with a "K10 insertion" and partial sequence deletions in the promoter region of the pvcrt-o gene, necessitating vigilance.

Dataset Information

Plasmodium vivax resistance to chloroquine in Madagascar: clinical efficacy and polymorphisms in pvmdr1 and pvcrt-o genes.

Publications

Plasmodium vivax resistance to chloroquine in Madagascar: clinical efficacy and polymorphisms in pvmdr1 and pvcrt-o genes.

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