Asymptomatic Plasmodium falciparum infections may not be shortened by acquired immunity.
Asymptomatic Plasmodium falciparum infections may not be shortened by acquired immunity.
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DOI：
10.1186/s12936-015-0813-1
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发表时间：
2015-08-04
期刊：
影响因子：
3
通讯作者：
Smith T
中科院分区：
文献类型：
--
作者：
Bretscher MT;Maire N;Felger I;Owusu-Agyei S;Smith T
未经治疗的恶性疟原虫感染的持续时间是寄生虫生物学的一个定义特征。目前尚不清楚自然获得性免疫（NAI）是否可以缩短感染，尽管对疟疾控制和消除以及基础研究具有潜在影响。分析了在一年内收集的6份血液样本中存在恶性疟原虫msp 2基因型的数据，以及在1周内收集的4份样本，来自纳夫龙戈（加纳）的一个队列。数学模型假设指数，威布尔，伽玛，或对数正态感染持续时间分别估计为6个年龄组。该方法允许不同的克隆采集和检测率。最佳拟合（威布尔）平均持续时间为124天（儿童<5岁），179天（5-9岁）和70-90天（>10岁）。这种非单调的年龄模式并不表明NAI的感染清除作用，因为免疫力随着暴露而增加，因此，年龄也随之增加。先天免疫力的差异是一个更合理的解释。21%的血液期感染在1周内终止，与神经梅毒患者持续数月的感染形成鲜明对比（疟疾治疗数据）。这个百分比的年龄独立性提高了这种清除可能是由于宿主和寄生虫之间的先天机制或遗传不相容性，而不是NAI。在所有年龄段的宿主中，相当大比例的感染在血液中出现的最初几天或几周内被清除，而其他人则持续数月。尽管累积暴露和NAI随年龄增加而增加，但这显然并不意味着终止感染的比率增加。本文的在线版本（doi：10.1186/s12936-015-0813-1）包含补充材料，可供授权用户使用。
The duration of untreated Plasmodium falciparum infections is a defining characteristic of the parasite’s biology. It is not clear whether naturally acquired immunity (NAI) can shorten infections, despite the potential implications for malaria control and elimination as well as for basic research. Data on the presence of P. falciparum msp2 genotypes in six blood samples collected over one year was analysed, together with four samples collected over 1 week, from a cohort in Navrongo (Ghana). Mathematical models assuming either exponential, Weibull, gamma, or log-normal infection durations were estimated separately for six age-groups. The method allowed for varying clonal acquisition and detection rates. The best fitting (Weibull) mean durations were 124 days (children <5years old), 179 days (5–9 years), and 70–90 days (>10 years). This non-monotonic age pattern is not suggestive of an infection-clearing effect of NAI since immunity increases with exposure, and thus, age. Age-related differences in innate immunity are a more plausible explanation. 21% of blood-stage infections terminated within 1 week, in stark contrast to months of persistence in infections induced in neuro-syphilis patients (malariatherapy data). Age independence in this percentage raises the possibility that this clearance may result from innate mechanisms or genetic incompatibility between hosts and parasites, rather than from NAI. In all ages of hosts a substantial proportion of infections are cleared in the first days or weeks of appearance in the blood, while others persist for many months. Although cumulative exposure and NAI increase with age, this does apparently not translate into an increased rate of termination of infections. The online version of this article (doi:10.1186/s12936-015-0813-1) contains supplementary material, which is available to authorized users.