<i>pfmdr1</i> mutations associated with chloroquine resistance incur a fitness cost in <i>Plasmodium falciparum</i>

Hayward, Rhys; Saliba, Kevin J.; Kirk, Kiaran

doi:10.1111/j.1365-2958.2004.04470.x

Cited by 83 publications

(76 citation statements)

References 76 publications

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“…In this study, we investigated both of these mechanisms and found that each contributed to the observed instability. The loss of fitness observed can be attributed to the amplification of a large section on chromosome 5 and changes in the pfmdr1 CN, not additional mutations in pfmdr1, as previously reported (11), or in several resistance gene candidates, such as pfatp6, since no additional mutations were identified in the resistant progeny (6). Importantly, our study used cloned parasites, allowing us to distinguish deamplification of pfmdr1 from out-growth by a preexisting subpopulation of parasites with a low CN.…”

Section: Discussionmentioning

confidence: 52%

Deamplification of pfmdr1 -Containing Amplicon on Chromosome 5 in Plasmodium falciparum Is Associated with Reduced Resistance to Artelinic Acid In Vitro

Chen¹,

Chavchich²,

Peters

et al. 2010

Antimicrob Agents Chemother

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Amplification of the Plasmodium falciparum multidrug resistance 1 gene (pfmdr1) has been implicated in multidrug resistance, including in vitro resistance to artelinic acid (AL). The stability and fitness of having multiple copies of pfmdr1 are important factors due to their potential effects on the resistance phenotype of parasites. These factors were investigated by using an AL-resistant line of P. falciparum (W2AL80) and clones originating from W2AL80. A rapid reduction in pfmdr1 copy number (CN) was observed in the uncloned W2AL80 line; 63% of this population reverted to a CN of <3 without exposure to the drug. Deamplification of the pfmdr1 amplicon was then determined in three clones, each initially containing three copies of pfmdr1. Interestingly, two outcomes were observed during 3 months without drug pressure. In one clone, parasites with fewer than 3 copies of pfmdr1 emerged rapidly. In two other clones, the reversion was significantly delayed. In all subclones, the reduction in pfmdr1 CN involved the deamplification of the entire amplicon (19 genes). Importantly, deamplification of the pfmdr1 amplicon resulted in partial reversal of resistance to AL and increased susceptibility to mefloquine. These results demonstrate that multiple copies of the pfmdr1-containing amplicon in AL-resistant parasites are unstable when drug pressure is withdrawn and have practical implications for the maintenance and spread of parasites resistant to artemisinin derivatives.

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Section: Discussionmentioning

confidence: 52%

Deamplification of pfmdr1 -Containing Amplicon on Chromosome 5 in Plasmodium falciparum Is Associated with Reduced Resistance to Artelinic Acid In Vitro

Chen¹,

Chavchich²,

Peters

et al. 2010

Antimicrob Agents Chemother

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“…Other studies have documented cases where drug resistanceassociated mutations confer a fitness disadvantage in the absence of drug pressure (20,21), but this does not seem to be the case with Pfmspdbl2. This could be due to the modest change in drug response conferred by the C591S mutation or perhaps because compensatory mutations that restore parasite fitness have occurred.…”

Section: Discussionmentioning

confidence: 97%

Modulation of PF10_0355 (MSPDBL2) Alters Plasmodium falciparum Response to Antimalarial Drugs

Tyne

Uboldi

Healer

et al. 2013

Antimicrob Agents Chemother

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bMalaria's ability to rapidly adapt to new drugs has allowed it to remain one of the most devastating infectious diseases of humans. Understanding and tracking the genetic basis of these adaptations are critical to the success of treatment and intervention strategies. The novel antimalarial resistance locus PF10_0355 (Pfmspdbl2) was previously associated with the parasite response to halofantrine, and functional validation confirmed that overexpression of this gene lowered parasite sensitivity to both halofantrine and the structurally related antimalarials mefloquine and lumefantrine, predominantly through copy number variation. Here we further characterize the role of Pfmspdbl2 in mediating the antimalarial drug response of Plasmodium falciparum. Knockout of Pfmspdbl2 increased parasite sensitivity to halofantrine, mefloquine, and lumefantrine but not to unrelated antimalarials, further suggesting that this gene mediates the parasite response to a specific class of antimalarial drugs. A single nucleotide polymorphism encoding a C591S mutation within Pfmspdbl2 had the strongest association with halofantrine sensitivity and showed a high derived allele frequency among Senegalese parasites. Transgenic parasites expressing the ancestral Pfmspdbl2 allele were more sensitive to halofantrine and structurally related antimalarials than were parasites expressing the derived allele, revealing an allele-specific effect on drug sensitivity in the absence of copy number effects. Finally, growth competition experiments showed that under drug pressure, parasites expressing the derived allele of Pfmspdbl2 outcompeted parasites expressing the ancestral allele within a few generations. Together, these experiments demonstrate that modulation of Pfmspdbl2 affects malaria parasite responses to antimalarial drugs. Malaria drug resistance poses a serious threat to treatment and control efforts (1, 2). Loci such as pfcrt, dhfr, and pfmdr1 are all known to play a role in mediating Plasmodium falciparum drug resistance and can do so through mutations or copy number variation (CNV) (3), but the precise mechanisms of resistance to many antimalarial drugs are poorly understood. Additionally, these well-known loci do not fully explain the range of responses observed in resistant parasites, suggesting that other loci may be involved in mediating parasite drug sensitivity (4, 5).Pfmspdbl2, also called PF10_0355, PF3D7_1036300, and MSP3.8, is a novel antimalarial resistance locus recently identified in a genome-wide association study (GWAS) of 50 global parasite isolates with a high-density single nucleotide polymorphism (SNP) array (6). CNV was also observed at this locus among natural parasite isolates, and parasites with more than one copy of Pfmspdbl2 tended to be more resistant to halofantrine. Overexpression of either the sensitive or the resistant allele of Pfmspdbl2 made parasites less sensitive to halofantrine, mefloquine, and lumefantrine but not to structurally unrelated antimalarials. This validated Pfmspdbl2 as a novel antimalaria...

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“…In a recent study, Hayward et al (2005) proposed that growth rate differences in genetically modified parasites result from a fitness impact of mutations introduced in pfmdr1. Using merozoite number as a growth criteria they ruled out differential merozoite production as contributing to growth differences in these lines.…”

Section: Discussionmentioning

confidence: 99%

Quantitative dissection of clone-specific growth rates in cultured malaria parasites

Reilly

Wang

Steuter

et al. 2007

International Journal for Parasitology

106

131

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Measurement of parasite proliferation in cultured red blood cells underpins many facets of malaria research, from drug sensitivity assays to assessing the impact of experimentally altered genes on parasite growth, virulence and fitness. Pioneering efforts to grow Plasmodium falciparum in cultured red blood cells revolutionized malaria research and spurred the development of semi-high throughput growth assays using radio-labeled hypoxanthine (Hx), an essential nucleic acid precursor, as a reporter of whole-cycle proliferation (Trager and Jensen, 1976;Desjardins et al., 1979). The isotopic Hx assay remains the standard quantitative growth assay with which newernon-radioactive procedures based on fluorescent DNA dyes or ELISA are compared. All of these readouts are surrogate reporters of changes in bulk parasitemias, reflecting proliferation over entire asexual reproductive cycles. While quantitatively robust and amenable to semi-high-throughput applications, these methods are blind to the underlying developmental and cellular events of growth in human red blood cells. Modern whole-genome tools including gene knockouts, mutagenesis and small molecule screens promise to reveal much about basic parasite biology; however methods to precisely quantify the within-cycle growth process are needed. Here we elaborate on the classical growth index, i.e.changes in parasitemia, by quantifying sub-phenotypes of a rapid proliferator, the multi-drug resistant clone Dd2, and a standard wild type clone, HB3. These data illustrate differences in cycle duration, merozoite production, and invasion rate and efficiency that underpin Dd2's average twofold proliferation advantage over HB3 per erythrocytic cycle. The ability to refine growth phenotypes will inform the search for molecular determinants of differential parasite growth rates and broaden our understanding of killing mechanisms and cellular targets of antimalarial drugs.

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pfmdr1 mutations associated with chloroquine resistance incur a fitness cost in Plasmodium falciparum

Cited by 83 publications

References 76 publications

Deamplification of pfmdr1 -Containing Amplicon on Chromosome 5 in Plasmodium falciparum Is Associated with Reduced Resistance to Artelinic Acid In Vitro

Deamplification of pfmdr1 -Containing Amplicon on Chromosome 5 in Plasmodium falciparum Is Associated with Reduced Resistance to Artelinic Acid In Vitro

Modulation of PF10_0355 (MSPDBL2) Alters Plasmodium falciparum Response to Antimalarial Drugs

Quantitative dissection of clone-specific growth rates in cultured malaria parasites

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