Department of Human Parasitology, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, 442000, China.
Department of Infectious Diseases, Renmin Hospital, Hubei University of Medicine, Shiyan, 442000, China.
Malar J. 2020 Nov 25;19(1):434. doi: 10.1186/s12936-020-03509-w.
Anti-malarial drug resistance is a severe challenge for eventual control and global elimination of malaria. Resistance to sulfadoxine-pyrimethamine (SP) increases as mutations accumulate in the Pfdhfr and Pfdhps genes. This study aimed to assess the polymorphisms and prevalence of mutation in these genes in the Plasmodium falciparum infecting migrant workers returning to Wuhan, China.
Blood samples were collected for 9 years (2011-2019). Parasite genomic DNA was extracted from blood spots on filter paper. The mutations were evaluated by nested PCR and sequencing. The single-nucleotide polymorphisms (SNPs) and haplotypes of the Pfdhfr and Pfdhps genes were analysed.
Pfdhfr codon 108 showed a 94.7% mutation rate, while for Pfdhps, the rate for codon 437 was 79.0%. In total, five unique haplotypes at the Pfdhfr locus and 11 haplotypes at the Pfdhps locus were found while the Pfdhfr-Pfdhps combined loci revealed 28 unique haplotypes. A triple mutant (IRNI) of Pfdhfr was the most prevalent haplotype (84.4%). For Pfdhps, a single mutant (SGKAA) and a double mutant (SGEAA) were detected at frequencies of 37.8 and 22.3%, respectively. Among the combined haplotypes, a quadruple mutant (IRNI-SGKAA) was the most common, with a 30.0% frequency, followed by a quintuplet mutant (IRNI-SGEAA) with a frequency of 20.4%.
The high prevalence and saturation of Pfdhfr haplotypes and the medium prevalence of Pfdhps haplotypes demonstrated in the present data will provide support for predicting the status and progression of antifolate resistance in malaria-endemic regions and imported malaria in nonendemic areas. Additional interventions to evaluate and prevent SP resistance should be continuously considered.
抗疟药物耐药性是疟疾最终控制和全球消除的严重挑战。随着 Pfdhfr 和 Pfdhps 基因中的突变积累，磺胺多辛-乙胺嘧啶（SP）的耐药性增加。本研究旨在评估感染返回中国武汉的农民工的疟原虫中这些基因的多态性和突变流行率。
采集了 9 年（2011-2019 年）的血样。从滤纸上的血斑中提取寄生虫基因组 DNA。通过巢式 PCR 和测序评估突变。分析 Pfdhfr 和 Pfdhps 基因的单核苷酸多态性（SNP）和单倍型。
Pfdhfr 密码子 108 的突变率为 94.7%，而 Pfdhps 密码子 437 的突变率为 79.0%。总共在 Pfdhfr 基因座发现了 5 个独特的单倍型，在 Pfdhps 基因座发现了 11 个单倍型，而 Pfdhfr-Pfdhps 联合基因座则显示了 28 个独特的单倍型。Pfdhfr 的三重突变（IRNI）是最常见的单倍型（84.4%）。在 Pfdhps 中，检测到单突变（SGKAA）和双突变（SGEAA）的频率分别为 37.8%和 22.3%。在联合单倍型中，四重突变（IRNI-SGKAA）最为常见，频率为 30.0%，其次是五重突变（IRNI-SGEAA），频率为 20.4%。
本研究数据表明，Pfdhfr 单倍型的高流行率和饱和以及 Pfdhps 单倍型的中流行率，将为预测疟疾流行地区和非流行地区输入性疟疾的抗叶酸耐药状态和进展提供支持。应不断考虑采取额外的干预措施来评估和预防 SP 耐药性。
