Background

Lumefantrine and mefloquine are used worldwide in artemisinin-based combination therapy (ACT) of malaria. Better understanding of drug susceptibility and resistance is needed and can be obtained from studies of genetic crosses.

Methods

Drug response phenotypes of a cross between Plasmodium falciparum lines 803 (Cambodia) and GB4 (Ghana) were obtained as half-maximal effective concentrations (EC₅₀s) and days to recovery (DTR) after 24 h exposure to 500 nM lumefantrine. EC₅₀s of mefloquine, halofantrine, chloroquine, and dihydroartemisinin were also determined. Quantitative trait loci (QTL) analysis and statistical tests with candidate genes were used to identify polymorphisms associated with response phenotypes.

Results

Lumefantrine EC₅₀s averaged 5.8-fold higher for the 803 than GB4 parent, and DTR results were 3–5 and 16–18 days, respectively. In 803 × GB4 progeny, outcomes of these two lumefantrine assays showed strong inverse correlation; these phenotypes also correlated strongly with mefloquine and halofantrine EC₅₀s. By QTL analysis, lumefantrine and mefloquine phenotypes mapped to a chromosome 5 region containing codon polymorphisms N86Y and Y184F in the P. falciparum multidrug resistance 1 protein (PfMDR1). Statistical tests of candidate genes identified correlations between inheritance of PfK13 Kelch protein polymorphism C580Y (and possibly K189T) and lumefantrine and mefloquine susceptibilities. Correlations were detected between lumefantrine and chloroquine EC₅₀s and polymorphisms N326S and I356T in the CVIET-type P. falciparum chloroquine resistance transporter (PfCRT) common to 803 and GB4.

Conclusions

Correlations in this study suggest common mechanisms of action in lumefantrine, mefloquine, and halofantrine responses. PfK13 as well as PfMDR1 and PfCRT polymorphisms may affect access and/or action of these arylaminoalcohol drugs at locations of hemoglobin digestion and heme metabolism. In endemic regions, pressure from use of lumefantrine or mefloquine in ACTs may drive selection of PfK13 polymorphisms along with versions of PfMDR1 and PfCRT associated with lower susceptibility to these drugs.

中文翻译：

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pfmdr1、pfcrt 和 pfk13 多态性与恶性疟原虫杂交中本芴醇和甲氟喹敏感性关联的证据

背景

Lumefantrine 和甲氟喹在全球范围内用于基于青蒿素的疟疾联合疗法 (ACT)。需要更好地了解药物敏感性和耐药性，这可以通过遗传杂交研究获得。

方法

恶性疟原虫品系 803（柬埔寨）和 GB4（加纳）之间杂交的药物反应表型是在暴露于 500 nM 苯芴醇 24 小时后获得的半最大有效浓度（EC ₅₀ s）和恢复天数（DTR）。还测定了甲氟喹、卤泛群、氯喹和二氢青蒿素的EC _{50 s。}使用数量性状位点（QTL）分析和候选基因的统计测试来识别与反应表型相关的多态性。

结果

803 的Lumefantrine EC ₅₀ s 平均比 GB4 母体高 5.8 倍，DTR 结果分别为 3-5 天和 16-18 天。在 803 × GB4 后代中，这两种苯芴醇测定结果显示出很强的负相关性；_{这些表型也与甲氟喹和卤泛群 EC 50} s密切相关。通过QTL分析，苯芴醇和甲氟喹表型定位到恶性疟原虫多药耐药1蛋白（PfMDR1）中含有密码子多态性N86Y和Y184F的5号染色体区域。候选基因的统计测试确定了 PfK13 Kelch 蛋白多态性 C580Y（可能还有 K189T）的遗传与本芴醇和甲氟喹敏感性之间的相关性。在803 和 GB4 共有的CVIET 型恶性疟原虫氯喹抗性转运蛋白 (PfCRT) 中，检测了本芴醇和氯喹 EC _{50 s 以及多态性 N326S 和 I356T 之间的相关性。}

结论

本研究中的相关性表明本芴醇、甲氟喹和卤芴醇反应中存在共同的作用机制。PfK13 以及 PfMDR1 和 PfCRT 多态性可能会影响这些芳基氨基醇药物在血红蛋白消化和血红素代谢部位的进入和/或作用。在流行地区，ACT 中使用本芴醇或甲氟喹的压力可能会推动 PfK13 多态性以及与这些药物敏感性较低相关的 PfMDR1 和 PfCRT 版本的选择。