Comparative and functional genomics of Toxoplasma and Hammondia hammondi

项目总结/摘要： 弓形虫是人类重要的条件致病菌，可引起严重的疾病， 发育中的胎儿和艾滋病毒/艾滋病患者。寄生虫的发育对于其引起严重的 疾病，但它如何做到这一点的确切机制知之甚少。T.弓形虫也调节 通过分泌大量效应物感染的细胞。大部分工作旨在了解T. 弓形虫能够引起疾病的研究主要集中在T。gondii本身一个创新的替代方案， 方法是进行T.弓形虫及其近亲揭示 以前未知的寄生虫毒力和发育调节机制。Hammondia寄生虫 哈蒙迪就是这样一个亲戚，我们在前一个资助期的工作已经将这种生物体发展成为一种 一个强大的比较模型来探测T.弓形虫生物学的进化背景。在这次更新中，我们 跟踪上一个资助期的两个观察结果：1）T。弓形虫的独特之处在于， 兼性细胞调节其向静止包囊期的转化;弓形虫的独特之处在于， 改变宿主细胞周期，这可能与抑制宿主抗寄生虫反应有关。在目标1中， 使用聚焦RNAseq筛选来鉴定T. gondii的发育，利用H.哈蒙迪 自然过滤器，专注于相关的候选基因。这一目标的成功是通过使用新的 转基因方法哈蒙迪和初步数据支持的前提下，我们的候选人的基础 approach.在目标2中，我们确定T. gondii和H.哈蒙迪差异调节的变化， 感染的宿主细胞，重点关注未被充分认识的宿主途径，包括DNA损伤反应， 细胞衰老这一目标的成功得益于我们在T. gondii和H. hammondi子孢子和体外测定，以及在H.哈蒙迪将允许 让我们在这种生物体中进行首次跨物种互补实验。总体而言， 建立在前一个资助期的工作，旨在确定重要的表型差异之间 这些密切相关的寄生虫物种，然后确定它们的分子机制。我们预计这些 研究的新发现，T.弓形虫调节生长和发育，以及它如何能够 抑制各种宿主防御。这两条调查路线将为以下方面确定新的途径： 治疗性干预，无论是针对寄生虫本身还是宿主反应， 生存

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.