Drug Susceptibility and Genetic Evaluation of
            <i>Plasmodium falciparum</i>
            Isolates Obtained in Four Distinct Geographical Regions of Kenya

Mbaisi, Abigael; Liyala, Pamela; Eyase, Fredrick; Achilla, R.; Akala, Hosea; Wangui, Julia; Mwangi, Josphat; Osuna, Finnley; Alam, Uzma; Smoak, Bonnie L.; Davis, Jon; Kyle, Dennis E.; Coldren, Rodney L.; Mason, Carl J.; Waters, Norman C.

doi:10.1128/aac.48.9.3598-3601.2004

Cited by 25 publications

(42 citation statements)

References 38 publications

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“…17 For example, about 30% of CQ IC 50 s and 50% of MQ IC 50 s in SYBR Green I assays exceeded previously established in vitro discriminative "resistance" values of 45 ng/mL and 10 ng/mL, respectively. 17 The IC 50 ranges for two P. falciparum reference clones, D6 and W2, paralleled their expected CQ and MQ sensitivity profiles. These observations underscored adaptability of the SYBR Green I IC 50 assay to a field-based laboratory.…”

Section: Discussionmentioning

confidence: 94%

“…Purple bars: median IC 50 in P. falciparum field isolates obtained 1997-2002 (culture-adapted, radioisotope uptake assay). 17 Black lines on CQ, MQ, and QN graphs: IC 50 threshold values considered discriminative for "resistant" P. falciparum isolates (culture-adapted, radioisotope uptake assay).…”

Section: Discussionmentioning

confidence: 99%

“…17 The AR median IC 50 values for SYBR Green I IEV and culture-adapted P. falciparum isolates were about 2-to 4-fold higher than the earlier 3 H-hypoxanthine assays, respectively. SYBR Green I background RFU experiments.…”

Section: Subject Enrollment and Follow Upmentioning

confidence: 99%

“…As in earlier work, mutant and mixed (mutant + wild) genotypes were combined to depict total mutant genotype populations. 17 Associations between the Pfmdr1 codon 86 SNPs and CQ, MQ, and AR IC 50 values are shown in Figure 4A-C. Plasmodium falciparum field isolates with Pfmdr1 codon 86 mutation (86Y) (66% of isolates) had a higher median CQ IC 50 (lower CQ sensitivity), in comparison with Pfmdr1 codon 86 wild (N86) samples. For MQ and AR, P. falciparum isolates with Pfmdr1 codon 86Y had a lower median IC 50 , in comparison with Pfmdr1 codon 86 wild, both statistically significant ( P < 0.05).…”

Section: Subject Enrollment and Follow Upmentioning

confidence: 99%

“…Further dilutions were in complete RPMI 1640 media to the desired starting concentration, followed by serial 2-fold dilutions to generate 10 concentrations for IC 50 testing. 17 The concentration ranges (ng/mL), from highest to lowest, were CQ (1,000 to 1.953), MQ (250 to 0.488), QN (2,000 to 3.906), AR (100 to 0.195), AQ (100 to 0.195), and DX (50,000 to 97.656). The drug solutions were prepared and used immediately, or stored at −80°C for not longer than 1 month before use.…”

Section: Introductionmentioning

confidence: 99%

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Antimalarial Drug Sensitivity Profile of Western Kenya Plasmodium falciparum Field Isolates Determined by a SYBR Green I in vitro Assay and Molecular Analysis

Akala¹,

Eyase²,

Cheruiyot³

et al. 2011

The American Society of Tropical Medicine and Hygiene

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In vitro drug sensitivity and molecular analyses of Plasmodium falciparum track drug resistance. DNA-binding fluorescent dyes like SYBR Green I may allow field laboratories, proximal to P. falciparum collection sites, to conduct drug assays. In 2007–2008, we assayed 121 P. falciparum field isolates from western Kenya for 50% inhibitory concentrations (IC50) against 6 antimalarial drugs using a SYBR Green I in vitro assay: 91 immediate ex vivo (IEV) and 30 culture-adapted, along with P. falciparum reference clones D6 (chloroquine [CQ] sensitive) and W2 (CQ resistant). We also assessed P. falciparum mdr1 (Pfmdr1) copy number and single nucleotide polymorphisms (SNPs) at four codons. The IC50s for IEV and culture-adapted P. falciparum isolates were similar, and approximated historical IC50s. For Pfmdr1, mean copy number was 1, with SNPs common at codons 86 and 184. The SYBR Green I assay adapted well to our field-based laboratory, for both IEV and culture-adapted P. falciparum, warranting continued use.

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Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 99%

Section: Subject Enrollment and Follow Upmentioning

confidence: 99%

Section: Subject Enrollment and Follow Upmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Antimalarial Drug Sensitivity Profile of Western Kenya Plasmodium falciparum Field Isolates Determined by a SYBR Green I in vitro Assay and Molecular Analysis

Akala¹,

Eyase²,

Cheruiyot³

et al. 2011

The American Society of Tropical Medicine and Hygiene

Self Cite

View full text Add to dashboard Cite

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Sulfadoxine-pyrimethamine resistance in Plasmodium falciparum: A zoomed image at the molecular level within a geographic context

2013

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Dissection of haplotype-specific drug response phenotypes in multiclonal malaria isolates

Nkhoma

Ahmed

Zaman

et al. 2021

International Journal for Parasitology: Drugs and Drug Resistan

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Natural infections of Plasmodium falciparum , the parasite responsible for the deadliest form of human malaria, often comprise multiple parasite lineages (haplotypes). Multiclonal parasite isolates may exhibit variable phenotypes including different drug susceptibility profiles over time due to the presence of multiple haplotypes. To test this hypothesis, three P. falciparum Cambodian isolates IPC_3445 (MRA-1236), IPC_5202 (MRA-1240) and IPC_6403 (MRA-1285) suspected to be multiclonal were cloned by limiting dilution, and the resulting clones genotyped at 24 highly polymorphic single nucleotide polymorphisms (SNPs). Isolates harbored up to three constituent haplotypes, and exhibited significant variability (p < 0.05) in susceptibility to chloroquine, mefloquine, artemisinin and piperaquine as measured by half maximal drug inhibitory concentration (IC 50 ) assays and parasite survival assays, which measure viability following exposure to pharmacologically relevant concentrations of antimalarial drugs. The IC 50 of the most abundant haplotype frequently reflected that of the uncloned parental isolate, suggesting that a single haplotype dominates the antimalarial susceptibility profile and masks the effect of minor frequency haplotypes. These results indicate that phenotypic variability in parasite isolates is often due to the presence of multiple haplotypes. Depending on intended end-use, clinical isolates should be cloned to yield single parasite lineages with well-defined phenotypes and genotypes. The availability of such standardized clonal parasite lineages through NIAID's BEI Resources program will aid research directed towards the development of diagnostics and interventions including drugs against malaria.

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Drug Susceptibility and Genetic Evaluation of Plasmodium falciparum Isolates Obtained in Four Distinct Geographical Regions of Kenya

Cited by 25 publications

References 38 publications

Antimalarial Drug Sensitivity Profile of Western Kenya Plasmodium falciparum Field Isolates Determined by a SYBR Green I in vitro Assay and Molecular Analysis

Antimalarial Drug Sensitivity Profile of Western Kenya Plasmodium falciparum Field Isolates Determined by a SYBR Green I in vitro Assay and Molecular Analysis

Sulfadoxine-pyrimethamine resistance in Plasmodium falciparum: A zoomed image at the molecular level within a geographic context

Dissection of haplotype-specific drug response phenotypes in multiclonal malaria isolates

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