经杀虫剂处理的蚊帐（ITNs）减少传播对寄生虫遗传种群结构的影响：I. 肯尼亚西部用微卫星标记对恶性疟原虫寄生虫的遗传多样性。
Effects of transmission reduction by insecticide-treated bed nets (ITNs) on parasite genetics population structure: I. The genetic diversity of Plasmodium falciparum parasites by microsatellite markers in western Kenya.
机构信息
Malaria Branch, Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
出版信息
Malar J. 2010 Dec 6;9:353. doi: 10.1186/1475-2875-9-353.
BACKGROUND
Insecticide-treated bed nets (ITNs) reduce malaria transmission and are an important prevention tool. However, there are still information gaps on how the reduction in malaria transmission by ITNs affects parasite genetics population structure. This study examined the relationship between transmission reduction from ITN use and the population genetic diversity of Plasmodium falciparum in an area of high ITN coverage in western Kenya.
METHODS
Parasite genetic diversity was assessed by scoring eight single copy neutral multilocus microsatellite (MS) markers in samples collected from P. falciparum-infected children (< five years) before introduction of ITNs (1996, baseline, n = 69) and five years after intervention (2001, follow-up, n = 74).
RESULTS
There were no significant changes in overall high mixed infections and unbiased expected heterozygosity between baseline (%MA = 94% and He = 0.75) and follow up (%MA = 95% and He = 0.79) years. However, locus specific analysis detected significant differences for some individual loci between the two time points. Pfg377 loci, a gametocyte-specific MS marker showed significant increase in mixed infections and He in the follow up survey (%MA = 53% and He = 0.57) compared to the baseline (%MA = 30% and He = 0.29). An opposite trend was observed in the erythrocyte binding protein (EBP) MS marker. There was moderate genetic differentiation at the Pfg377 and TAA60 loci (FST = 0.117 and 0.137 respectively) between the baseline and post-ITN parasite populations. Further analysis revealed linkage disequilibrium (LD) of the microsatellites in the baseline (14 significant pair-wise tests and ISA = 0.016) that was broken in the follow up parasite population (6 significant pairs and ISA = 0.0003). The locus specific change in He, the moderate population differentiation and break in LD between the baseline and follow up years suggest an underlying change in population sub-structure despite the stability in the overall genetic diversity and multiple infection levels.
CONCLUSIONS
The results from this study suggest that although P. falciparum population maintained an overall stability in genetic diversity after five years of high ITN coverage, there was significant locus specific change associated with gametocytes, marking these for further investigation.
背景
经杀虫剂处理的蚊帐（ITN）可降低疟疾传播，是一种重要的预防工具。然而，关于 ITN 降低疟疾传播对寄生虫遗传种群结构的影响，仍存在信息空白。本研究在肯尼亚西部高度覆盖 ITN 的地区，研究了 ITN 使用导致的传播减少与恶性疟原虫（Plasmodium falciparum）种群遗传多样性之间的关系。
方法
在引入 ITN 之前（1996 年，基线，n = 69）和干预五年后（2001 年，随访，n = 74），采集感染恶性疟原虫的儿童（< 5 岁）样本，通过评分 8 个单拷贝中性多位点微卫星（MS）标记，评估寄生虫遗传多样性。
结果
基线（%MA = 94%，He = 0.75）和随访（%MA = 95%，He = 0.79）年之间，整体高混合感染和无偏期望杂合度（unbiased expected heterozygosity）均无显著变化。然而，对个别基因座的特定分析显示，两个时间点之间存在显著差异。配子体特异性 MS 标记 Pfg377 基因座的混合感染和 He 在随访调查中显著增加（%MA = 53%，He = 0.57），而在基线时（%MA = 30%，He = 0.29）则相反。红细胞结合蛋白（EBP）MS 标记也呈现出相反的趋势。在基线和 ITN 后寄生虫群体之间，Pfg377 和 TAA60 基因座存在中度遗传分化（FST = 0.117 和 0.137）。进一步分析显示，基线时微卫星存在连锁不平衡（linkage disequilibrium，LD）（14 个显著的两两测试，ISA = 0.016），而在随访寄生虫群体中则不存在（6 个显著对，ISA = 0.0003）。尽管整体遗传多样性和多重感染水平保持稳定，但基线和随访年份之间 He 的变化、种群遗传分化的中度变化以及 LD 的破坏表明，尽管总体遗传多样性和多重感染水平保持稳定，但种群亚结构仍发生了显著变化。
结论
本研究结果表明，尽管在高度覆盖 ITN 五年后，恶性疟原虫种群的遗传多样性保持总体稳定，但与配子体相关的显著基因座特异性变化标记了进一步的研究。
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