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

描述（由申请人提供）：果蝇已作为理解先天免疫的分子遗传学的模型，但先天免疫系统的细胞部分在分子水平上的特征仍然很差。此外，有非常少的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，开发一个利用宿主与果蝇中可用的一系列遗传工具的系统将是特别有价值的。在之前的工作中，我们鉴定了许多被认为在果蝇细胞免疫应答中对内寄生蜂起作用的候选果蝇基因，包括参与模式识别、血细胞（血细胞）信号传导和血细胞迁移和黄蜂卵包囊所需的细胞骨架修饰的基因（Schlenke et al. 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免疫抑制毒液成分的天然黄蜂大型寄生虫之间的分子和进化的相互作用。我们将在功能上表征候选果蝇抗黄蜂免疫基因，并在自然种群中对黄蜂杀死成功的遗传变异负责的果蝇基因座进行遗传作图。我们还将通过使用cDNA文库和蛋白质测序的组合，从两种具有不同感染策略的密切相关的黄蜂的毒腺中鉴定毒液蛋白，来解决黄蜂方面的问题。cDNA序列将被用来产生标记，以遗传地图黄蜂基因座负责在自然种群中的黄蜂感染成功的遗传变异。最后，我们将通过收集果蝇免疫基因和黄蜂毒液基因的自然群体的DNA多态性和趋异数据，并通过使用标准群体遗传学和分子进化技术推断这些基因上的过去选择压力，来研究黄蜂-苍蝇相互作用的分子进化历史。公共卫生相关性：本计画的目的是了解果蝇细胞免疫反应与其大型寄生蜂毒液成分之间的分子与演化互动。这项工作将揭示果蝇先天免疫系统的基本要素，通才和专科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.