Dissecting the molecular basis of PfCRT-mediated antimalarial drug resistance

 描述（由申请人提供）：原生动物寄生虫恶性疟原虫是最致命的人类疟疾，并发症包括昏迷、贫血、呼吸窘迫和肾衰竭。由于目前没有有效的疫苗，化疗仍然是疟疾治疗和控制的基石。消除疟疾的努力受到氯喹（CQ）耐药性上升的阻碍，氯喹是一种安全，廉价和高效的药物。CQ抗性（CQR）主要由恶性疟原虫氯喹抗性转运蛋白（PfCRT）介导。除了介导CQR外，PfCRT还是寄生虫对一线青蒿素联合疗法（ACT）敏感性的调节剂，其疗效受到东南亚新兴多药耐药性（MDR）的威胁。虽然所有地理上不同的CQR寄生虫已获得多个单核苷酸多态性（SNP）的PfCRT，大概是为了平衡他们的耐药性和健身的要求，我们目前无法解释不同的区域PfCRT单倍型的患病率的时间变化。为了了解特定PfCRT SNP如何影响寄生虫的耐药性和适应性（目的1和2），我们将从遗传学上解剖两个CQR pfcrt等位基因，Ecu1110（来自厄瓜多尔）和Cam734（来自柬埔寨）。Ecu1110 pfcrt包含4个SNP，这是观察到的最少的，使其适合于导致获得耐药性的突变轨迹的研究。Cam734 pfcrt是迄今为止描述的最高度突变的等位基因，具有5个新的SNP，并作为研究pfcrt提供的寄生虫适应性的独特增益的原型。我们还将 探索PfCRT SNP促进对一线ACT组分（目标3），即青蒿素（ART）及其伙伴药物的耐药性的能力，这一努力将联合收割机的实验室研究与柬埔寨西部（MDR中心）的现场临床培训相结合。总之，我们的目的是（1）研究PfCRT SNP对CQ和其他临床显著抗疟药耐药性发展的贡献，（2）评估PfCRT SNP对CQ和其他临床显著抗疟药耐药性的影响。 PfCRT SNP对寄生虫适应性的影响，以及（3）评估PfCRT调节多药耐药寄生虫对ART和ACT伴侣药物敏感性的能力。这些研究有望对抗疟药物耐药性的遗传基础产生重要的新见解，包括pfcrt突变在调节一线联合治疗疗效中的作用，并将指导新策略的发展，以减少耐多药疟疾的全球影响。

 DESCRIPTION (provided by applicant): The protozoan parasite Plasmodium falciparum is responsible for the deadliest form of human malaria, with complications including coma, anemia, respiratory distress, and renal failure. With no effective vaccine at hand, chemotherapy remains the cornerstone for malaria treatment and control. Efforts to eradicate malaria have been hindered by the rise of resistance to chloroquine (CQ), an otherwise safe, cheap, and highly effective drug. CQ resistance (CQR) is primarily mediated by the P. falciparum Chloroquine Resistance Transporter (PfCRT). In addition to mediating CQR, PfCRT is a modulator of parasite susceptibility to first-line artemisinin- based combination therapies (ACTs), whose efficacy is endangered by emerging multidrug resistance (MDR) in Southeast Asia. While all geographically-distinct CQR parasites have acquired multiple single-nucleotide polymorphisms (SNPs) in PfCRT, presumably to balance their requirements for drug resistance and fitness, we are currently unable to explain temporal changes in the prevalence of different regional PfCRT haplotypes. To understand how specific PfCRT SNPs affect parasite drug resistance and fitness (Aims 1 and 2), we will genetically dissect two CQR pfcrt alleles, Ecu1110 (from Ecuador) and Cam734 (from Cambodia). Ecu1110 pfcrt contains 4 SNPs, the fewest observed, rendering it amenable to a study of the mutational trajectories that lead to acquisition of drug resistance. Cam734 pfcrt, the most highly mutated allele yet described, harbors 5 novel SNPs and serves as a prototype for the study of the unique gain of parasite fitness afforded by pfcrt. We will also explore the capacity of PfCRT SNPs to facilitate resistance to first-line ACT components (Aim 3), namely artemisinins (ARTs) and their partner drugs, an effort that will combine our laboratory-based investigations with on-site clinical training in western Cambodia, an epicenter of MDR. In summary, our aims are (1) to investigate the contribution of PfCRT SNPs to the development of resistance to CQ and other clinically significant antimalarials, (2) to evaluate the impact of PfCRT SNPs on parasite fitness, and (3) to assess the capacity of PfCRT to modulate susceptibility to ARTs and ACT partner drugs in multidrug-resistant parasites. These studies are expected to yield important new insights into the genetic basis of antimalarial drug resistance, including the role of pfcrt mutations in modulating the efficacy of first-line combination therapie, and will guide the development of novel strategies to reduce the global impact of multidrug-resistant malaria.