Project description:A genome wide association study (GWAS) testing association of parasite genotypes with clinically decreased piperaquine sensitivity phenotype Submission of genotypes from all microarray genotyped samples
Project description:The combination of piperaquine and dihydroartemisinin has recently become the official first-line therapy in several Southeast Asian countries. The pharmacokinetic mismatching of these drugs, whose plasma half lives are ∼20 days and ∼1 hr respectively, implies that recrudescent or new infections emerging shortly after treatment cessation will encounter piperaquine as a monotherapy agent. This creates substantial selection pressure for the emergence of resistance. To elucidate potential resistance determinants, we subjected cloned Plasmodium falciparum Dd2 parasites to continuous piperaquine pressure in vitro (47 nM, ∼two-fold higher than the Dd2 IC(50) value). The phenotype of outgrowth parasites was assayed in two clones, revealing an IC(50) value against piperaquine of 2.1 μM and 1.7 μM, over 100-fold greater than the parent. To identify the genetic determinant of resistance, we employed comparative whole-genome hybridization analysis. Compared to the Dd2 parent, this analysis found (in both resistant clones) a novel single nucleotide polymorphism in pfcrt, deamplification of an 82 kb region of chromosome 5 (that includes pfmdr1), and amplification of an adjacent 63 kb region of chromosome 5. Continued propagation without piperaquine selection pressure resulted in derivation of "revertant" piperaquine-sensitive parasites. These retained the pfcrt polymorphism and further deamplified the chromosome 5 segment that encompasses pfmdr1; however, these two independently generated revertants both lost the neighboring 63 kb amplification. These results suggest that a copy number variation event on chromosome 5 (825600-888300) is associated with piperaquine resistance. Transgenic studies are underway with individual genes in this segment to evaluate their contribution to piperaquine resistance.
Project description:The emergence of multidrug resistance in Plasmodium falciparum parasites presents a significant obstacle to the malaria elimination agenda. Resistance to piperaquine (PPQ), an important first-line partner drug, has spread across Southeast Asia where it has contributed to widespread treatment failures. The genetic cause of resistance to PPQ is attributable to a novel set of amino acid substitutions in the P. falciparum chloroquine resistance transporter (PfCRT). The objective of our study is to characterize gene expression signatures associated with PPQ-resistance associated PfCRT mutations by comparing transcriptional profiles of PPQ-resistant PfCRT mutants (F145I, G353V, M343L) and isogenic PPQ-sensitive lines that were generated by zinc finger nuclease (ZFN) based editing in a long-term adapted (Dd2).
Project description:Epigenetic mechanisms have been poorly understood in Plasmodium falciparum, the causative agent of malaria. To elucidate stage specific epigenetic regulations in P. falciparum, we performed genome-wide mapping of various histone modifications, nucleosomes and RNA Polymerase II. Our comprehensive analysis suggest that transcription initiation and elongation are distinct in Plasmodium. In this study, by analyzing histone modifications, nucleosome occupancy and RNA Polymerase II (Pol II) at three different IEC developmental stages of Plasmodium; ring, trophozoite and schizont, we tried to unravel the epigenetic mechanism associated with gene regulation. Examination of H3K27me3, H3K4me3, H3K9me3, H3K14ac, H3K4me1, H3K79me3, H3K27ac, H3K4me2, H3K9ac, H4ac, RNA Pol II and Histone H3 at three different stages of Plasmodium falciparum
Project description:Transcriptomic Analysis of Cultured Sporozoites of P. falciparum RNA-seq reads from each of three developmental stages (2 replicates per sample) were mapped to the reference Plasmodium falciparum genome, and gene expression levels were calculated for each sample.
Project description:Investigation of whole genome gene expression level changes in Plasmodium falciparum 3D7 delta-PfPuf2 mutant, compared to the wild-type strain 3D7. The mutation engineered into this strain render tanslational control. The mutants analyzed in this study are further described in Miao J, Li J, Fan Q, Li X, Li X, Cui L.2010. The Puf-family RNA-binding protein PfPuf2 regulates sexual development and sex differentiation in the malaria parasite Plasmodium falciparum. J Cell Sci. 123(7):1039-49 (PMID 20197405). A 12 chip study using total RNA recovered from six separate wild-type cultures of Plasmodium falciparum 3D7 at gametocyte stage III (three cultures) and stage V (three cultures) and six separate cultures of dalta PfPuf2 mutant at gametocyte stage III (three cultures) and stage V (three cultures). Each chip measures the expression level of 5,367 genes from Plasmodium falciparum 3D7 with 45-60 mer probes with two replicates on final array of 71618 probes.
Project description:Piperaquine Resistance is Associated with a Copy Number Variation on Chromosome 5 in Drug-Pressured Plasmodium falciparum Parasites