Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, Jazan University, Jazan, Kingdom of Saudi Arabia.
Medical Research Centre, Jazan University, Jazan, Kingdom of Saudi Arabia.
Malar J. 2020 Dec 2;19(1):446. doi: 10.1186/s12936-020-03524-x.
Despite significant progress in eliminating malaria from the Kingdom of Saudi Arabia, the disease is still endemic in the southwestern region of the country. Artesunate plus sulfadoxine-pyrimethamine (AS + SP) has been used in Saudi Arabia since 2007 as a first-line treatment for uncomplicated Plasmodium falciparum malaria. This study aimed to investigate the prevalence of mutations associated with resistance to artemisinin and sulfadoxine-pyrimethamine (SP) resistance in P. falciparum parasites circulating in Jazan region, southwestern Saudi Arabia.
A total of 151 P. falciparum isolates were collected between April 2018 and March 2019 from 12 of the governorates in Jazan region. Genomic DNA was extracted from dried blood spots and amplified using nested PCR. Polymorphisms in the propeller domain of the P. falciparum k13 (pfkelch13) gene and point mutations in the P. falciparum dihydrofolate reductase (pfdhfr) and dihydropteroate synthase (pfdhps) genes were identified by sequencing.
No mutations in the pfkelch13 propeller domain were found in any of the 151 isolates. However, point mutations in the pfdhfr and pfdhps genes were detected in 90.7% (137/151) of the isolates. The pfdhfr double mutations N51I + S108N (i.e. ACICNI haplotype) and triple mutations N51I + C59R + S108N (i.e. ACIRNI haplotype) were detected in 47% and 37.8% of the isolates, respectively. Moreover, the pfdhps single mutation at codon A437G and double mutations A437G + K540E (i.e. SGEAAI haplotype) were observed in 4.6% and 51.7% of the isolates, respectively. Interestingly, 23.8%, 25.1 and 12.6% of the isolates had quintuple, quadruple and triple mutated combined pfdhfr-pfdhps genotypes, respectively. Furthermore, significant associations were found between the prevalence of mutant haplotypes and the age, gender and nationality of the patients (P < 0.05).
This study revealed a high prevalence of point mutations in the pfdhfr and pfdhps genes of P. falciparum isolates from Jazan region, with quintuple and quadruple mutant pfdhfr-pfdhps genotypes reported for the first time in Saudi Arabia and the Arabian Peninsula. Despite the absence of the pfkelch13 mutation in the isolates examined, the pfdhfr and pfdhps mutations undermine the efficacy of SP partner drug, thereby threatening the main falciparum malaria treatment policy in Saudi Arabia, i.e. the use of AS + SP. Therefore, the continuous molecular and in-vivo monitoring of ACT efficacy in Jazan region is highly recommended.
尽管沙特阿拉伯王国在消除疟疾方面取得了重大进展，但该国西南部仍存在地方性疟疾。自 2007 年以来，青蒿琥酯加磺胺多辛-乙胺嘧啶（AS+SP）一直被用于沙特阿拉伯，作为治疗无并发症恶性疟原虫疟疾的一线药物。本研究旨在调查沙特阿拉伯西南部吉赞地区流行的恶性疟原虫寄生虫对青蒿素和磺胺多辛-乙胺嘧啶（SP）耐药相关突变的流行情况。
2018 年 4 月至 2019 年 3 月期间，从吉赞地区的 12 个省共采集了 151 株恶性疟原虫分离株。从干燥血斑中提取基因组 DNA，并用巢式 PCR 进行扩增。通过测序鉴定恶性疟原虫kelch13（pfkelch13）基因的螺旋桨结构域中的多态性和恶性疟原虫二氢叶酸还原酶（pfdhfr）和二氢叶酸合成酶（pfdhps）基因中的点突变。
在 151 个分离株中，未发现 pfkelch13 螺旋桨结构域中的突变。然而，在 90.7%（137/151）的分离株中检测到 pfdhfr 和 pfdhps 基因的点突变。检测到 pfdhfr 双突变 N51I+S108N（即 ACICNI 单倍型）和三重突变 N51I+C59R+S108N（即 ACIRNI 单倍型），分别占 47%和 37.8%。此外，在 4.6%和 51.7%的分离株中分别观察到 pfdhps 密码子 A437G 单突变和 A437G+K540E 双突变（即 SGEAAI 单倍型）。有趣的是，23.8%、25.1%和 12.6%的分离株分别具有五重、四重和三重突变的 pfdhfr-pfdhps 基因型。此外，突变单倍型的流行与患者的年龄、性别和国籍之间存在显著相关性（P<0.05）。
本研究揭示了吉赞地区恶性疟原虫分离株中 pfdhfr 和 pfdhps 基因的点突变率很高，首次在沙特阿拉伯和阿拉伯半岛报告了五重和四重突变的 pfdhfr-pfdhps 基因型。尽管在检测的分离株中未发现 pfkelch13 突变，但 pfdhfr 和 pfdhps 突变削弱了 SP 联合用药的疗效，从而威胁到沙特阿拉伯主要的恶性疟原虫治疗政策，即使用 AS+SP。因此，强烈建议在吉赞地区持续进行 ACT 疗效的分子和体内监测。
