Comparative and functional genomics of Toxoplasma and Hammondia hammondi

项目摘要/摘要： 弓形虫是一种重要的人类条件致病菌，可引起严重的人类疾病。 发育中的胎儿和艾滋病毒/艾滋病患者。寄生虫的发展对其造成严重的 然而，它如何做到这一点的确切机制却知之甚少。弓形虫也调节 通过大量效应器的分泌而感染的细胞。很多工作都是为了了解T。 能够致病的弓形虫一直只集中在弓形虫本身。一种创新的替代方案 方法是对弓形虫及其近亲进行功能和遗传比较，以揭示 以前未知的寄生虫毒力和发育调节机制。寄生虫哈蒙迪亚 Hammondi就是这样一个亲戚，我们在前一个资助期的工作已经将这个有机体发展成一种 从进化的角度探索弓形虫生物学的强大比较模型。在这次更新中，我们 对上一个供资期间的两点意见采取后续行动：1)弓形虫具有独特的能力 兼性地调节其向静止的包囊阶段的转换；2)弓形虫具有独特的能力 改变宿主细胞周期，这可能与抑制宿主的抗寄生虫反应有关。在目标1中，我们 使用聚焦的RNAseq屏幕识别弓形虫发育的新调控因子，使用H.hammondi作为 自然筛选，专注于相关候选基因。这一目标的成功是通过使用新的 H.hammondi的转基因方法和初步数据支持我们的候选人的前提 接近。在目标2中，我们确定了弓形虫和哈蒙迪是如何差异地调节 感染的宿主细胞，重点放在被低估的宿主途径上，包括DNA损伤反应和 细胞衰老。这一目标的成功得益于我们在弓形虫和H. 哈蒙迪子孢子和体外分析，以及在哈蒙迪中的转基因方法，这将允许 美国首次在这种生物中进行跨物种互补实验。总体而言，这些研究 在前一个供资期间的基础上开展工作，以确定重要的表型差异 这些密切相关的寄生虫物种，然后确定它们的分子机制。我们期待着这些 研究导致弓形虫如何调节生长和发育以及它如何能够 压制各种各样的主机防御。这两条调查路线都将确定新的途径 治疗干预，无论是针对寄生虫本身还是被发现对其至关重要的宿主反应 生死存亡。

PROJECT SUMMARY/ABSTRACT: Toxoplasma gondii is an important opportunistic pathogen of humans where it can cause severe disease in the developing fetus and those with HIV/AIDS. Parasite development is critical for its ability to cause severe disease, yet the precise mechanisms for how it does this are poorly understood. T. gondii is also modulates the cell that in infects via secretion of a multitude of effectors. Much of the work aimed at understanding how T. gondii is able to cause disease has focused exclusively on T. gondii itself. An innovative alternative to this approach is to perform functional and genetic comparisons between T. gondii and its near relatives to reveal previously unknown mechanisms of parasite virulence and developmental regulation. The parasite Hammondia hammondi is one such relative, and our work in the prior funding period has developed this organism into a powerful comparative model for probing T. gondii biology from an evolutionary context. In this renewal we follow up on two observations from the prior funding period: 1) that T. gondii is unique in its ability to facultatively regulate its conversion to the quiescent cyst stage and 2) that T. gondii is unique in its ability to alter the host cell cycle and that this may be linked to suppression of host anti-parasitic responses. In Aim 1 we use a focused RNAseq screen to identify new regulators of T. gondii development, using H. hammondi as a natural filter to focus on relevant candidate genes. Success of this Aim is facilitated by the use of new transgenic approaches for H. hammondi and preliminary data supporting the premise of our candidate based approach. In Aim 2 we determine how T. gondii and H. hammondi differentially regulate changes in the infected host cell, with a focus on underappreciated host pathways including DNA damage responses and cellular senescence. Success of this aim is facilitated by our extensive experience with T. gondii and H. hammondi sporozoites and in vitro assays, as well as transgenic approaches in H. hammondi that will permit us to perform the first ever cross-species complementation experiments in this organism. Overall these studies build on work during the prior funding period aimed at identifying important phenotypic differences between these closely related parasite species and then determining their molecular mechanisms. We expect these studies to result in new discoveries of how T. gondii regulates in growth and development and how it is able to suppress a wide variety of host defenses. Both of these lines of inquiry will identify new avenues for therapeutic intervention, whether they target the parasite itself or host responses found to be critical for its survival.