Tanzania is currently implementing therapeutic efficacy studies (TES) in areas of varying malaria transmission intensities as per the World Health Organization (WHO) recommendations. In TES, distinguishing reinfection from recrudescence is critical for the determination of anti-malarial efficacy. Recently, the WHO recommended genotyping polymorphic coding genes, merozoite surface proteins 1 and 2 (msp1 and msp2), and replacing the glutamate-rich protein (glurp) gene with one of the highly polymorphic microsatellites in Plasmodium falciparum to adjust the efficacy of antimalarials in TES. This study assessed the polymorphisms of six neutral microsatellite markers and their potential use in TES, which is routinely performed in Tanzania. Plasmodium falciparum samples were obtained from four TES sentinel sites, Kibaha (Pwani), Mkuzi (Tanga), Mlimba (Morogoro) and Ujiji (Kigoma), between April and September 2016. Parasite genomic DNA was extracted from dried blood spots on filter papers using commercial kits. Genotyping was done using six microsatellites (Poly-α, PfPK2, TA1, C3M69, C2M34 and M2490) by capillary method, and the data were analysed to determine the extent of their polymorphisms and genetic diversity at the four sites. Overall, 83 (88.3%) of the 94 samples were successfully genotyped (with positive results for ≥ 50.0% of the markers), and > 50.0% of the samples (range = 47.6–59.1%) were polyclonal, with a mean multiplicity of infection (MOI) ranging from 1.68 to 1.88 among the four sites. There was high genetic diversity but limited variability among the four sites based on mean allelic richness (RS = 7.48, range = 7.27–8.03, for an adjusted minimum sample size of 18 per site) and mean expected heterozygosity (He = 0.83, range = 0.80–0.85). Cluster analysis of haplotypes using STRUCTURE, principal component analysis, and pairwise genetic differentiation (FST) did not reveal population structure or clustering of parasites according to geographic origin. Of the six markers, Poly-α was the most polymorphic, followed by C2M34, TA1 and C3M69, while M2490 was the least polymorphic. Microsatellite genotyping revealed high polyclonality and genetic diversity but no significant population structure. Poly-α, C2M34, TA1 and C3M69 were the most polymorphic markers, and Poly-α alone or with any of the other three markers could be adopted for use in TES in Tanzania.

中文翻译：

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微卫星揭示了坦桑尼亚大陆不同传播强度地区的高度多态性和用于抗疟功效研究的巨大潜力

坦桑尼亚目前正在根据世界卫生组织（WHO）的建议，在不同疟疾传播强度的地区实施治疗效果研究（TES）。在 TES 中，区分再感染和复发对于确定抗疟疾功效至关重要。最近，世界卫生组织建议对多态性编码基因裂殖子表面蛋白1和2（msp1和msp2）进行基因分型，并用恶性疟原虫中的一种高度多态性微卫星替换富含谷氨酸的蛋白（glurp）基因，以调整抗疟药的功效。 TES。本研究评估了 6 个中性微卫星标记的多态性及其在坦桑尼亚常规进行的 TES 中的潜在用途。恶性疟原虫样本取自 2016 年 4 月至 9 月期间，从四个 TES 哨点：Kibaha (Pwani)、Mkuzi (Tanga)、Mlimba (Morogoro) 和 Ujiji (Kigoma)。商业套件。通过毛细管法使用六个微卫星（Poly-α、PfPK2、TA1、C3M69、C2M34 和 M2490）进行基因分型，并分析数据以确定其在四个位点的多态性和遗传多样性的程度。总体而言，94 个样本中有 83 个 (88.3%) 成功进行了基因分型（≥ 50.0% 的标记呈阳性结果），并且 > 50.0% 的样本（范围 = 47.6–59.1%）是多克隆的，平均多重数为四个站点的感染率（MOI）范围为1.68至1.88。基于平均等位基因丰富度（RS = 7.48，范围 = 7.27-8.03，调整后的最小样本量为每个位点 18）和平均预期杂合度（He = 0.83，范围 = 0.80–0.85）。使用结构、主成分分析和成对遗传分化 (FST) 进行的单倍型聚类分析并未揭示种群结构或根据地理起源的寄生虫聚类。在这六个标记中，Poly-α 的多态性最高，其次是 C2M34、TA1 和 C3M69，而 M2490 的多态性最低。微卫星基因分型显示出高度的多克隆性和遗传多样性，但没有显着的群体结构。Poly-α、C2M34、TA1 和 C3M69 是多态性最强的标记，Poly-α 单独或与其他三种标记中的任何一个一起可用于坦桑尼亚的 TES。