Mukhongo Harriet Natabona, Kinyua Johnson Kang'ethe, Weldemichael Yishak Gebrekidan, Kasili Remmy Wekesa
College of Health Sciences; Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Juja, P.O. Box 62000-00200, Nairobi, Kenya.
College of Science; Department of Biology, Eritrea Institute of Technology, Asmara, P.O. Box 12676, Mai-Nefhi, Asmara, Eritrea.
F1000Res. 2024 Jun 12;10:628. doi: 10.12688/f1000research.54195.3. eCollection 2021.
Antimalarial drug resistance is a major challenge hampering malaria control and elimination. About three-quarters of Eritrea's population resides in the malaria-endemic western lowlands of the country. , the leading causative parasite species, has developed resistance to basically all antimalarials. Continued surveillance of drug resistance using genetic markers provides important molecular data for treatment policies which complements clinical studies, and strengthens control efforts. This study sought to genotype point mutations associated with resistance to sulfadoxine-pyrimethamine and artemisinin, in dried-blood spots from three hospitals in the western lowlands of Eritrea.
Dried-blood spot samples were collected from patients visiting Adi Quala, Keren and Gash Barka Hospitals, between July and October, 2014. The patients were followed up after treatment with first line artesunate-amodiaquine, and dried-blood spots were collected on day three after treatment. Nested polymerase chain reaction and Sanger sequencing techniques were employed to genotype point mutations in the (PF3D7_0417200), (PF3D7_0810800) and (PF3D7_1343700) partial gene regions.
Sequence data analyses of PCR-positive isolates found wild-type artemisinin haplotypes associated with resistance (Y493Y, R539R, I543I) in three isolates, whereas four mutant antifolate haplotypes associated with resistance were observed in six isolates. These included the triple-mutant (S108N, C59R, N51I) haplotype, the double-mutant (N51I, S108N) haplotype, the single-mutant (K540E) haplotype, and the mixed-mutant (S108N, N51I + K540E) haplotype. Other findings observed were, a rare non-synonymous V45A mutation in four isolates, and a synonymous R449R in one isolate.
The mutant antifolate haplotypes observed indicate a likely existence of full SP resistance. Further studies can be carried out to estimate the prevalence of SP resistance. The wild-type artemisinin haplotypes observed suggest artemisinin is still an effective treatment. Continuous monitoring of point mutations associated with delayed parasite clearance in ART clinical studies is recommended.
抗疟药物耐药性是阻碍疟疾控制与消除的一项重大挑战。厄立特里亚约四分之三的人口居住在该国疟疾流行的西部低地。该国主要的致病寄生虫物种已对基本上所有抗疟药物产生了耐药性。利用基因标记持续监测耐药性可为治疗政策提供重要的分子数据，这对临床研究起到补充作用，并加强防控工作。本研究旨在对厄立特里亚西部低地三家医院的干血斑中与磺胺多辛 - 乙胺嘧啶及青蒿素耐药性相关的点突变进行基因分型。
2014年7月至10月期间，从到访阿迪夸拉、克伦和加什巴尔卡医院的患者中采集干血斑样本。患者接受一线青蒿琥酯 - 阿莫地喹治疗后进行随访，并在治疗后第三天采集干血斑。采用巢式聚合酶链反应和桑格测序技术对二氢叶酸还原酶（PF3D7_0417200）、二氢蝶酸合酶（PF3D7_0810800）和细胞色素P450 2D6（PF3D7_1343700）部分基因区域的点突变进行基因分型。
对PCR阳性分离株的序列数据分析发现，三个分离株中存在与耐药性相关的野生型青蒿素单倍型（Y493Y、R539R、I543I），而在六个分离株中观察到四种与耐药性相关的突变抗叶酸单倍型。这些包括三突变的二氢叶酸还原酶（S108N、C59R、N51I）单倍型、双突变的二氢叶酸还原酶（N51I、S108N）单倍型、单突变的二氢叶酸还原酶（K540E）单倍型以及混合突变的二氢叶酸还原酶（S108N、N51I + K540E）单倍型。观察到的其他发现包括，四个分离株中存在罕见的非同义二氢蝶酸合酶V45A突变，以及一个分离株中存在同义的二氢蝶酸合酶R449R。
观察到的突变抗叶酸单倍型表明可能存在对磺胺多辛 - 乙胺嘧啶的完全耐药性。可开展进一步研究以估计磺胺多辛 - 乙胺嘧啶耐药性的流行情况。观察到的野生型青蒿素单倍型表明青蒿素仍是一种有效的治疗药物。建议在青蒿素治疗临床研究中持续监测与寄生虫清除延迟相关的点突变。
