The Sri Lankan paradox: high genetic diversity in Plasmodium vivax populations despite decreasing levels of malaria transmission.
The Sri Lankan paradox: high genetic diversity in Plasmodium vivax populations despite decreasing levels of malaria transmission.
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DOI：
10.1017/s0031182013002278
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发表时间：
2014-06
期刊：
影响因子：
2.4
通讯作者：
Karunaweera ND
中科院分区：
文献类型：
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作者：
Gunawardena S;Ferreira MU;Kapilananda GM;Wirth DF;Karunaweera ND
在这里，我们研究了斯里兰卡最近疟疾传播的急剧下降是否导致当地间日疟原虫种群的主要瓶颈，导致有效种群规模大幅减少。为此，我们在5年（2003-2007年）期间（斯里兰卡13个地区）收集的185例间日疟原虫患者分离株中分型了14个高度多态性的微卫星标记。总体而言，我们发现了高度的多态性，有184个独特的单倍型（每个位点12-46个等位基因），平均遗传多样性（期望杂合度）为0.8744。近69% （n = 127）分离株存在多克隆感染（MCI）。种群间存在显著的时空差异（FST = 0.04 - 0.25; P≤0.0009）。有效种群规模相对较高，但在2003-4至2006-7期间呈下降趋势（估计为45661至22896或10513至7057，取决于所使用的基础模型）。我们使用了三种方法——即等位基因频率分布的模式转移、杂合子过量检测和m比统计数据——来检验最近群体瓶颈的证据，但只有m比统计数据的低值（范围在0.15 - 0.33之间，平均值为0.26）表明存在这种瓶颈。尽管斯里兰卡间日疟原虫的人口规模急剧下降，但遗传多样性和MCI比例一直很高，有效种群规模变化不大，这表明保持严格的控制和监测措施以防止再次发生的重要性。
Here we examined whether the recent dramatic decline in malaria transmission in Sri Lanka led to a major bottleneck in the local Plasmodium vivax population, with a substantial decrease in the effective population size. To this end, we typed 14 highly polymorphic microsatellite markers in 185 P. vivax patient isolates collected from 13 districts in Sri Lanka over a period of 5 years (2003–2007). Overall, we found a high degree of polymorphism, with 184 unique haplotypes (12–46 alleles per locus) and average genetic diversity (expected heterozygosity) of 0·8744. Almost 69% (n = 127) isolates had multiple-clone infections (MCI). Significant spatial and temporal differentiation (FST = 0·04–0·25; P⩽0·0009) between populations was observed. The effective population size was relatively high but showed a decline from 2003–4 to 2006–7 periods (estimated as 45661 to 22896 or 10513 to 7057, depending on the underlying model used). We used three approaches – namely, mode-shift in allele frequency distribution, detection of heterozygote excess and the M-ratio statistics – to test for evidence of a recent population bottleneck but only the low values of M-ratio statistics (ranging between 0·15–0·33, mean 0·26) were suggestive of such a bottleneck. The persistence of high genetic diversity and high proportion of MCI, with little change in effective population size, despite the collapse in demographic population size of P. vivax in Sri Lanka indicates the importance of maintaining stringent control and surveillance measures to prevent resurgence.