Analysis of Genetic Variation across the Encapsidated Genome of Microplitis demolitor Bracovirus in Parasitoid Wasps.
Analysis of Genetic Variation across the Encapsidated Genome of Microplitis demolitor Bracovirus in Parasitoid Wasps.
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DOI：
10.1371/journal.pone.0158846
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Burke GR
中科院分区：
文献类型：
--
作者：
Burke GR
昆虫寄生蜂必须在另一种昆虫体内或体表完成其生命周期的一部分，最终导致宿主昆虫死亡。一组寄生蜂，即“小腹蜂复合体”（膜翅目：茧蜂科），与有益的共生病毒建立联系，这对于宿主的成功寄生至关重要。这些病毒被称为布拉科病毒，以整合形式存在于黄蜂基因组中，并在发育过程中激活在黄蜂卵巢中复制，最终在寄生过程中传递到宿主昆虫中。宿主与拟寄生物相互作用的致命性质，加上病毒参与介导这些相互作用，导致了这样的假设：布拉科病毒与宿主进行军备竞赛，导致病毒（和宿主）基因反复适应。采用深度测序来表征寄生蜂物种 Microplitis demolitor 的实验室和野外群体中衣壳布拉科病毒基因组的序列变异。与预期相反，很少有证据表明毒力基因之间存在正向选择，而毒力基因通常表现出纯化选择的特征。这些数据表明，宿主-寄生虫相互作用的动态可能不会导致循环适应，并且适应在时间上的变化可能比之前预期的更大。
Insect parasitoids must complete part of their life cycle within or on another insect, ultimately resulting in the death of the host insect. One group of parasitoid wasps, the ‘microgastroid complex’ (Hymenoptera: Braconidae), engage in an association with beneficial symbiotic viruses that are essential for successful parasitism of hosts. These viruses, known as Bracoviruses, persist in an integrated form in the wasp genome, and activate to replicate in wasp ovaries during development to ultimately be delivered into host insects during parasitism. The lethal nature of host-parasitoid interactions, combined with the involvement of viruses in mediating these interactions, has led to the hypothesis that Bracoviruses are engaged in an arms race with hosts, resulting in recurrent adaptation in viral (and host) genes. Deep sequencing was employed to characterize sequence variation across the encapsidated Bracovirus genome within laboratory and field populations of the parasitoid wasp species Microplitis demolitor. Contrary to expectations, there was a paucity of evidence for positive directional selection among virulence genes, which generally exhibited signatures of purifying selection. These data suggest that the dynamics of host-parasite interactions may not result in recurrent rounds of adaptation, and that adaptation may be more variable in time than previously expected.