A Model System For Host-Pathogen Interactions: Drosophila And Its Parasitic Wasps

描述（由申请人提供）：果蝇已被用作理解先天免疫分子遗传学的模型，但先天免疫系统的细胞部分在分子水平上仍然缺乏表征。此外，很少有模型系统可用于研究自然宿主-病原体相互作用的遗传基础，特别是真核宿主和病原体之间的相互作用，利用宿主和果蝇中可用的遗传工具阵列开发一个模型系统将特别有价值。在之前的工作中，我们发现了一些候选果蝇基因，这些基因被认为在果蝇对类内寄生蜂的细胞免疫反应中发挥作用，包括参与模式识别、血细胞信号传导和细胞骨架修饰的基因，这些基因是血细胞迁移和黄蜂卵封装所必需的（Schlenke etal . 2007）。在这里，我们提出了一系列的实验，旨在了解果蝇细胞免疫反应和其天然黄蜂大寄生虫的免疫抑制毒液成分之间的分子和进化相互作用。我们将对候选果蝇抗黄蜂免疫基因进行功能表征，并绘制果蝇在自然种群中成功杀死黄蜂的遗传变异位点的遗传图谱。我们还将利用cDNA文库和蛋白质测序相结合的方法，从具有不同感染策略的两种密切相关的黄蜂的毒腺中鉴定毒液蛋白，从而解决黄蜂方面的问题。cDNA序列将用于生成标记，以遗传定位黄蜂在自然种群中感染成功的遗传变异位点。最后，我们将通过收集自然种群中果蝇免疫基因和黄蜂毒液基因的DNA多态性和差异数据，并利用标准群体遗传学和分子进化技术推断这些基因过去的选择压力，来研究蜂蝇相互作用的分子进化史。公共卫生相关性：本项目的目的是了解果蝇细胞免疫反应与黄蜂大寄生虫毒液成分之间的分子和进化相互作用。这项工作将揭示果蝇先天免疫系统的基本要素，通才和专才寄生虫抑制免疫反应的机制，以及在进化过程中参与拮抗相互作用的苍蝇免疫基因和黄蜂毒液基因。

DESCRIPTION (provided by applicant): Drosophila has served as a model for understanding the molecular genetics of innate immunity, but the cellular part of the innate immune system remains poorly characterized at the molecular level. Furthermore, there are very few model systems available for studying the genetic basis of natural host-pathogen interactions, particularly between eukaryotic hosts and pathogens, and developing one utilizing a host with the array of genetic tools available in Drosophila would be especially valuable. In previous work, we identified a number of candidate Drosophila genes thought to play a role in the fly cellular immune response against endoparasitoid wasps, including genes involved in pattern recognition, hemocyte (blood cell) signaling, and cytoskeletal modifications necessary for hemocyte migration and encapsulation of wasp eggs (Schlenke et al. 2007). Here, we propose a series of experiments aimed at understanding the molecular and evolutionary interactions between the Drosophila cellular immune response and the immune suppressive venom components of its natural wasp macroparasites. We will functionally characterize candidate Drosophila anti-wasp immunity genes, and genetically map Drosophila loci responsible for genetic variation in wasp killing success in natural populations. We will also tackle the wasp side of the equation by identifying venom proteins from the venom glands of two closely related wasps with divergent infection strategies, using a combination of cDNA library and protein sequencing. The cDNA sequences will be used to generate markers to genetically map wasp loci responsible for genetic variation in wasp infection success in natural populations. Finally, we will study the molecular evolutionary history of the wasp-fly interaction by collecting DNA polymorphism and divergence data from natural populations for Drosophila immune genes and wasp venom genes, and by inferring the past selection pressures on these genes using standard population genetics and molecular evolution techniques. PUBLIC HEALTH RELEVANCE: The purpose of this project is to understand the molecular and evolutionary interactions between the Drosophila cellular immune response and the venom components of its wasp macroparasites. This work will uncover basic elements of the Drosophila innate immune system, mechanisms by which generalist and specialist parasites suppress the immune response, and the fly immune genes and wasp venom genes that engage in antagonistic interactions over evolutionary time.