PNAS:疟原虫对蚊子物种的适应

摘要 : 美国国立卫生研究院国立过敏症与传染病研究所科研人员报告了一种控制疟疾寄生虫被不同的蚊子物种传播的能力的基因。

美国国立卫生研究院国立过敏症与传染病研究所科研人员报告了一种控制疟疾寄生虫被不同的蚊子物种传播的能力的基因。疟疾寄生虫恶性疟原虫(Plasmodium falciparum)起源于非洲，随着人类迁移到其他大陆而在全球传播。Carolina Barillas-Mury及其同事用来自非洲、亚洲和南美洲的恶性疟原虫株型感染了来自这些地区的蚊子。每一种蚊子物种都最容易受到来自与蚊子同一个地区的疟原虫株型的感染，这提示寄生虫适应了不同的蚊子病媒。让蚊子免疫系统的一个组成部分沉默，能增加蚊子对来自不同大陆的寄生虫的易感性，这提示蚊子的免疫系统阻止了外来寄生虫的感染。此前的研究已经证明的Pfs47基因能让恶性疟原虫规避蚊子免疫系统，而这个基因的不同的变种出现在不同的大陆。把Pfs47基因替换成来自一个不同的大陆的变种，足以增强这种寄生虫感染来自那个大陆的蚊子的能力。这组作者提出，Pfs47通过与一个特定的蚊子受体的相互作用，能让这种寄生虫规避蚊子免疫系统的探测，但是这种寄生虫为了生存下来和得到传播，对于一个特定的蚊子物种，它必须携带正确的Pfs47的变种。这组作者说，Pfs47 可能充当阻断疟疾传播的疫苗的一个靶标。

原文链接：

Plasmodium evasion of mosquito immunity and global malaria transmission: The lock-and-key theory

原文摘要：

Plasmodium falciparum malaria originated in Africa and became global as humans migrated to other continents. During this journey, parasites encountered new mosquito species, some of them evolutionarily distant from African vectors. We have previously shown that the Pfs47 protein allows the parasite to evade the mosquito immune system of Anopheles gambiae mosquitoes. Here, we investigated the role of Pfs47-mediated immune evasion in the adaptation of P. falciparum to evolutionarily distant mosquito species. We found that P. falciparum isolates from Africa, Asia, or the Americas have low compatibility to malaria vectors from a different continent, an effect that is mediated by the mosquito immune system. We identified 42 different haplotypes of Pfs47 that have a strong geographic population structure and much lower haplotype diversity outside Africa. Replacement of the Pfs47 haplotypes in a P. falciparum isolate is sufficient to make it compatible to a different mosquito species. Those parasites that express a Pfs47 haplotype compatible with a given vector evade antiplasmodial immunity and survive. We propose that Pfs47-mediated immune evasion has been critical for the globalization of P. falciparum malaria as parasites adapted to new vector species. Our findings predict that this ongoing selective force by the mosquito immune system could influence the dispersal of Plasmodium genetic traits and point to Pfs47 as a potential target to block malaria transmission. A new model, the “lock-and-key theory” of P. falciparum globalization, is proposed, and its implications are discussed.

doi: 10.1073/PNAS.1520426112

作者：Alvaro Molina-Cruz

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