Kenya Medical Research Institute (KEMRI)/Wellcome Trust Collaborative Research Program, P.O. Box 230, 80108 Kilifi, Kenya.
Antimicrob Agents Chemother. 2010 Aug;54(8):3302-7. doi: 10.1128/AAC.00325-10. Epub 2010 Jun 1.
Resistance to the amino alcohol quinine has been associated with polymorphisms in pfnhe, a sodium hydrogen exchanger. We investigated the role of this gene in quinine resistance in vitro in isolates from Kenya. We analyzed pfnhe whole-gene polymorphisms, using capillary sequencing, and pfcrt at codon 76 (pfcrt-76) and pfmdr1 at codon 86 (pfmdr1-86), using PCR-enzyme restriction methodology, in 29 isolates from Kilifi, Kenya, for association with the in vitro activities of quinine and 2 amino alcohols, mefloquine and halofantrine. In vitro activity was assessed as the drug concentration that inhibits 50% of parasite growth (IC50). The median IC50s of quinine, halofantrine, and mefloquine were 92, 22, and 18 nM, respectively. The presence of 2 DNNND repeats in microsatellite ms4760 of pfnhe was associated with reduced susceptibility to quinine (60 versus 227 nM for 1 and 2 repeats, respectively; P<0.05), while 3 repeats were associated with restoration of susceptibility. The decrease in susceptibility conferred by the 2 DNNND repeats was more pronounced in parasites harboring the pfmdr1-86 mutation. No association was found between susceptibility to quinine and the pfcrt-76 mutation or between susceptibility to mefloquine or halofantrine and the pfnhe gene and the pfcrt-76 and pfmdr1-86 mutations. Using previously published data on the in vitro activities of chloroquine, lumefantrine, piperaquine, and dihydroartemisinin, we investigated the association of their activities with pfnhe polymorphism. With the exception of a modulation of the activity of lumefantrine by a mutation at position 1437, pfnhe did not modulate their activities. Two DNNND repeats combined with the pfmdr1-86 mutation could be used as an indicator of reduced susceptibility to quinine.
对氨基酸醇奎宁的耐药性与钠氢交换蛋白 pfnhe 的多态性有关。我们研究了该基因在肯尼亚分离株体外奎宁耐药性中的作用。我们使用毛细管测序分析了 pfnhe 全基因多态性，使用 PCR-酶限制方法分析了 pfcrt 76 位密码子（pfcrt-76）和 pfmdr1 86 位密码子（pfmdr1-86），并将 29 个来自肯尼亚基利菲的分离株与体外奎宁和 2 种氨基酸醇（甲氟喹和卤泛群）的活性相关联。体外活性评估为抑制寄生虫生长 50%的药物浓度（IC50）。奎宁、卤泛群和甲氟喹的中位数 IC50 分别为 92、22 和 18 nM。pfnhe 微卫星 ms4760 中存在 2 个 DNNND 重复与对奎宁的敏感性降低相关（分别为 60 和 227 nM，1 和 2 个重复；P<0.05），而 3 个重复与敏感性恢复相关。在携带 pfmdr1-86 突变的寄生虫中，2 个 DNNND 重复引起的敏感性降低更为显著。未发现奎宁敏感性与 pfcrt-76 突变之间、甲氟喹或卤泛群敏感性与 pfnhe 基因和 pfcrt-76 及 pfmdr1-86 突变之间存在相关性。使用先前发表的关于氯喹、青蒿琥酯、哌喹和双氢青蒿素体外活性的数据，我们研究了其活性与 pfnhe 多态性的关联。除了位置 1437 的突变对青蒿琥酯活性的调节外，pfnhe 没有调节其活性。2 个 DNNND 重复与 pfmdr1-86 突变的结合可作为奎宁敏感性降低的指标。
