Department of Biochemistry, Faculty of Medicine, University of Khartoum, Khartoum, Sudan.
Department of Medical Parasitology and Entomology, Faculty of Medical Laboratory Sciences, Al Neelain University, Khartoum, Sudan.
Malar J. 2020 Feb 18;19(1):78. doi: 10.1186/s12936-020-03165-0.
Plasmodium falciparum malaria is a public health problem worldwide. Malaria treatment policy has faced periodic changes due to emergence of drug resistant parasites. In Sudan chloroquine has been replaced by artesunate and sulfadoxine/pyrimethamine (AS/SP) in 2005 and to artemether-lumefantrine (AL) in 2017, due to the development of drug resistance. Different molecular markers have been used to monitor the status of drug resistant P. falciparum. This study aimed to determine the frequency of malaria drug resistance molecular markers in Southeast Sudan.
The samples of this study were day zero dried blood spot samples collected from efficacy studies in the Blue Nile State from November 2015 to January 2016. A total of 130 samples were amplified and sequenced using illumina Miseq platform. The molecular markers included were Pfcrt, Pfmdr1, Pfdhfr, Pfdhps, Pfk13, exonuclease and artemisinin resistant (ART-R) genetic background (Pfmdr2, ferroredoxine, Pfcrt and Pfarps10).
Resistance markers for chloroquine were detected in 25.8% of the samples as mutant haplotype Pfcrt 72-76 CVIET and 21.7% Pfmdr1 86Y. Pfdhfr mutations were detected in codons 51, 59 and 108. The ICNI double-mutant haplotype was the most prevalent (69%). Pfdhps mutations were detected in codons 436, 437, 540, 581 and 613. The SGEGA triple-mutant haplotype was the most prevalent (43%). In Pfdhfr/Pfdhps combined mutation, quintuple mutation ICNI/SGEGA is the most frequent one (29%). Six of the seven treatment failure samples had quintuple mutation and the seventh was quadruple. This was significantly higher from the adequately responsive group (P < 0.01). Pfk13 novel mutations were found in 7 (8.8%) samples, which were not linked to artemisinin resistance. Mutations in ART-R genetic background genes ranged from zero to 7%. Exonuclease mutation was not detected.
In this study, moderate resistance to chloroquine and high resistance to SP was observed. Novel mutations of Pfk13 gene not linked to treatment failure were described. There was no resistance to piperaquine the partner drug of dihydroartemisinin/piperaquine (DHA-PPQ).
恶性疟原虫疟疾是全球公共卫生问题。由于抗药性寄生虫的出现，疟疾治疗政策不断发生变化。2005 年，苏丹已用青蒿琥酯和磺胺多辛/乙胺嘧啶（AS/SP）取代氯喹，2017 年又用青蒿素-甲氟喹（AL）取代，因为氯喹已出现抗药性。不同的分子标记物已被用于监测恶性疟原虫抗药性的状况。本研究旨在确定苏丹东南部疟疾药物抗药性分子标记物的流行率。
本研究的样本为 2015 年 11 月至 2016 年 1 月在青尼罗州进行疗效研究时采集的零日干血斑样本。共对 130 个样本进行扩增和测序，使用 illumina Miseq 平台。分子标记包括 PfCRT、Pfmdr1、Pfdhfr、Pfdhps、PfK13、外切酶和青蒿素耐药（ART-R）遗传背景（Pfmdr2、铁还原蛋白、PfCRT 和 PfARPS10）。
25.8%的样本检测到氯喹耐药标记物，表现为突变单倍型 PfCRT 72-76 CVIET 和 21.7%Pfmdr1 86Y。检测到 Pfdhfr 密码子 51、59 和 108 点突变。ICNI 双突变单倍型最为常见（69%）。Pfdhps 突变发生在密码子 436、437、540、581 和 613。SGEGA 三突变单倍型最为常见（43%）。在 Pfdhfr/Pfdhps 联合突变中，最常见的是 quintuple 突变 ICNI/SGEGA（29%）。6 个治疗失败样本中有 quintuple 突变，第 7 个样本为 quadruple 突变。与反应良好组相比，这一比例显著升高（P<0.01）。在 7 个样本（8.8%）中发现 PfK13 新突变，但与青蒿素耐药无关。ART-R 遗传背景基因的突变范围从 0 到 7%。未检测到外切酶突变。
本研究观察到对氯喹中度耐药和对磺胺多辛高度耐药。描述了与治疗失败无关的 PfK13 基因突变。二氢青蒿素/哌喹（DHA-PPQ）的联合用药中，对哌喹无耐药性。
