Early Genomic Amplifications in Blood-Stages of ARMD Plasmodium falciparum Acquiring De Novo Drug Resistance
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ABSTRACT:
ORGANISM(S): Plasmodium falciparum Dd2 Plasmodium falciparum
PROVIDER: GSE35950 | GEO | 2013/05/01
SECONDARY ACCESSION(S): PRJNA151983
REPOSITORIES: GEO
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Project description:This SuperSeries is composed of the SubSeries listed below. Refer to individual Series
2013-05-01 | E-GEOD-35950 | biostudies-arrayexpress
Project description:While many molecular changes associated with commonly used antimalarials are known, there remain important questions on how parasites arrive at the correct causal molecular solutions in a haploid genome. We selected for resistance to DSM1, a novel dihydroorotate dehydrogenase (DHODH) inhibitor with a non-biological triazolopyrimidine scaffold, in P. falciparum with the Accelerated Resistance to Multiple Drugs (ARMD) trait. While direct sequencing revealed no mutations in the target DHODH gene, comparative genomic hybridizations from four independently selected DSM1-resistant clones showed a large, single 34-95kb amplification in each clone. Each amplified region always included the DHODH locus. The length of this region and the resulting 2- to 3-fold DHODH copy number increase were verified at the RNA and protein level. DSM1 resistance was stable over several months of in vitro culture. Additional selection at higher DSM1 concentrations caused further gains in CNVs at the DHODH locus. The present system validated DHODH as a key target of the triazolopyrimidine antimalarial, DSM1 and, more importantly, captured large, random CNVs as an early step in the initiation of drug resistance in malaria parasites. This defined system is expected to be valuable for characterizing early, causal molecular steps leading to successful drug resistance
2013-05-01 | GSE35949 | GEO
Project description:While many molecular changes associated with commonly used antimalarials are known, there remain important questions on how parasites arrive at the correct causal molecular solutions in a haploid genome. We selected for resistance to DSM1, a novel dihydroorotate dehydrogenase (DHODH) inhibitor with a non-biological triazolopyrimidine scaffold, in P. falciparum with the Accelerated Resistance to Multiple Drugs (ARMD) trait. While direct sequencing revealed no mutations in the target DHODH gene, comparative genomic hybridizations from four independently selected DSM1-resistant clones showed a large, single 34-95kb amplification in each clone. Each amplified region always included the DHODH locus. The length of this region and the resulting 2- to 3-fold DHODH copy number increase were verified at the RNA and protein level. DSM1 resistance was stable over several months of in vitro culture. Additional selection at higher DSM1 concentrations caused further gains in CNVs at the DHODH locus. The present system validated DHODH as a key target of the triazolopyrimidine antimalarial, DSM1 and, more importantly, captured large, random CNVs as an early step in the initiation of drug resistance in malaria parasites. This defined system is expected to be valuable for characterizing early, causal molecular steps leading to successful drug resistance RNA from P. falciparum DSM1 resistant cell-line was hybridized against RNA of parental strain, Dd2. DSM1 resistant cell culture was maintained under DSM1 at 333 nM, microarray data were obtained from three hybridizations using RNA from three independent parasite cultures
2013-05-01 | E-GEOD-35949 | biostudies-arrayexpress
Project description:While many molecular changes associated with commonly used antimalarials are known, there remain important questions on how parasites arrive at the correct causal molecular solutions in a haploid genome. We selected for resistance to DSM1, a novel dihydroorotate dehydrogenase (DHODH) inhibitor with a non-biological triazolopyrimidine scaffold, in P. falciparum with the Accelerated Resistance to Multiple Drugs (ARMD) trait. While direct sequencing revealed no mutations in the target DHODH gene, comparative genomic hybridizations from four independently selected DSM1-resistant clones showed a large, single 34-95kb amplification in each clone. Each amplified region always included the DHODH locus. The length of this region and the resulting 2- to 3-fold DHODH copy number increase were verified at the RNA and protein level. DSM1 resistance was stable over several months of in vitro culture. Additional selection at higher DSM1 concentrations caused further gains in CNVs at the DHODH locus. The present system validated DHODH as a key target of the triazolopyrimidine antimalarial, DSM1 and, more importantly, captured large, random CNVs as an early step in the initiation of drug resistance in malaria parasites. This defined system is expected to be valuable for characterizing early, causal molecular steps leading to successful drug resistance
2013-05-01 | GSE35732 | GEO
Project description:While many molecular changes associated with commonly used antimalarials are known, there remain important questions on how parasites arrive at the correct causal molecular solutions in a haploid genome. We selected for resistance to DSM1, a novel dihydroorotate dehydrogenase (DHODH) inhibitor with a non-biological triazolopyrimidine scaffold, in P. falciparum with the Accelerated Resistance to Multiple Drugs (ARMD) trait. While direct sequencing revealed no mutations in the target DHODH gene, comparative genomic hybridizations from four independently selected DSM1-resistant clones showed a large, single 34-95kb amplification in each clone. Each amplified region always included the DHODH locus. The length of this region and the resulting 2- to 3-fold DHODH copy number increase were verified at the RNA and protein level. DSM1 resistance was stable over several months of in vitro culture. Additional selection at higher DSM1 concentrations caused further gains in CNVs at the DHODH locus. The present system validated DHODH as a key target of the triazolopyrimidine antimalarial, DSM1 and, more importantly, captured large, random CNVs as an early step in the initiation of drug resistance in malaria parasites. This defined system is expected to be valuable for characterizing early, causal molecular steps leading to successful drug resistance gDNA from P. falciparum DSM1 resistant cell-line was hybridized against gDNA of parental strain, Dd2. DSM1 resistant cell culture was maintained under DSM1 at 333 nM, microarray data were obtained from three hybridizations using gDNA from three independent parasite cultures
2013-05-01 | E-GEOD-35732 | biostudies-arrayexpress
Project description:BackgroundCopy number variations (CNVs) of the Plasmodium falciparum multidrug resistance 1 (pfmdr1), P. falciparum plasmepsin2 (pfplasmepsin2) and P. falciparum GTP cyclohydrolase 1 (pfgch1) genes are associated with anti-malarial drug resistance in P. falciparum malaria. Droplet digital PCR (ddPCR) assays have been developed for accurate assessment of CNVs in several human genes. The aim of the present study was to develop and validate ddPCR assays for detection of the CNVs of P. falciparum genes associated with resistance to anti-malarial drugs.MethodsA multiplex ddPCR assay was developed to detect the CNVs in the pfmdr1 and pfplasmepsin2 genes, while a duplex ddPCR assay was developed to detect CNV in the pfgch1 gene. The gene copy number (GCN) quantification limit, as well as the accuracy and precision of the ddPCR assays were determined and compared to conventional quantitative PCR (qPCR). In order to reduce the cost of testing, a multiplex ddPCR assay of two target genes, pfmdr1 and pfplasmepsin2, was validated. In addition, the CNVs of genes of field samples collected from Thailand from 2015 to 2019 (n = 84) were assessed by ddPCR and results were compared to qPCR as the reference assay.ResultsThere were no significant differences between the GCN results obtained from uniplex and multiplex ddPCR assays for detection of CNVs in the pfmdr1 and pfplasmepsin2 genes (p = 0.363 and 0.330, respectively). Based on the obtained gene copy number quantification limit, the accuracy and percent relative standard deviation (%RSD) value of the multiplex ddPCR assay were 95% and 5%, respectively, for detection of the CNV of the pfmdr1 gene, and 91% and 5% for detection of the CNV of the pfplasmepsin2 gene. There was no significant difference in gene copy numbers assessed by uniplex or duplex ddPCR assays regarding CNV in the pfgch1 gene (p = 0.276). The accuracy and %RSD value of the duplex ddPCR assay were 95% and 4%, respectively, regarding pfgch1 GCN. In the P. falciparum field samples, pfmdr1 and pfplasmepsin2 GCNs were amplified in 15% and 27% of samples from Ubon Ratchathani, Thailand, while pfgch1 GCN was amplified in 50% of samples from Yala, Thailand. There was 100% agreement between the GCN results obtained from the ddPCR and qPCR assays (κ = 1.00). The results suggested that multiplex ddPCR assay is the optional assay for the accurate detection of gene copy number without requiring calibration standards, while the cost and required time are reduced. Based on the results of this study, criteria for GCN detection by ddPCR analysis were generated.ConclusionsThe developed ddPCR assays are simple, accurate, precise and cost-effective tools for detection of the CNVs in the pfmdr1, pfplasmepsin2 and pfgch1 genes of P. falciparum. The ddPCR assay is a useful additional tool for the surveillance of anti-malarial drug resistance.
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