Molecular pathogenesis of Francisella tularnesis

描述（由申请人提供）：致命疾病土拉菌病的病原体，土拉菌弗朗西斯菌（Ft），是一种革兰氏阴性高传染性细胞内细菌，被列为a类选择生物恐怖制剂。巨噬细胞内Ft的细胞内复制是疾病表现所必需的。这是相当惊人的知识相对缺乏的分子和细胞方面的发病机制，这种多功能和极其致命的病原体。我们的初步数据表明，在进入巨噬细胞后，含ft吞噬体（FCP）逃避溶酶体融合。感染后2-12小时，生物体从吞噬体中逃逸到细胞质中。我们的假设是，Ft进入巨噬细胞的特定模式允许生物体调节其吞噬体的生物发生，通过特定的输出细菌效应物，进入一个不与溶酶体融合的生态位，并允许生物体随后逃逸到细胞质中，在那里进行复制。为了验证这一假设，我们的具体目标是：1 .解剖胞内土拉菌的细胞生物学以及在非酸化的内体样晚期停止吞噬体生物发生的独特机制。2。鉴定在阻止吞噬体生物发生和逃逸到细胞质中有缺陷的突变体。3。描述参与阻止吞噬体生源和逃逸到细胞质中的细菌因素。意义：A类选择性生物恐怖制剂Ft的发病机制是细胞内细菌病原体中研究和了解最少的一种。了解这种生物如何利用巨噬细胞增殖和疾病表现是我们对兔热病认识的基础。参与利用巨噬细胞的细菌效应物是潜在的治疗靶点，也是潜在的候选疫苗。

DESCRIPTION (provided by applicant): The causative agent of the fatal disease Tularemia, Francisella tularensis (Ft), is a gram negative highly infectious intracellular bacterium, that is classified as a Category A Select Bioterrorism Agent. Intracellular replication of Ft within macrophages is essential for disease manifestation. It is rather astonishing the relative paucity of knowledge about the molecular and cellular aspects of pathogenesis of this versatile and extremely virulent pathogen. Our preliminary data indicate that upon entry into macrophages, Ft-containing phagosome (FCP) evades lysosomal fusion. The organism escapes from the phagosome into the cytoplasm by 2-12h post-infection. Our hypothesis is that specific modes of entry of Ft into macrophages allow the organism to modulate biogenesis of its phagosome, by specific exported bacterial effectors, into a niche that does not fuse to the lysosomes and allow subsequent escape of the organism into the cytoplasm, where it replicates. To test this hypothesis, our specific aims are: I. To dissect the cell biology of intracellular F. tularensis and the unique mechanisms that halt phagosome biogenesis at a non-acidified late endosome-like stage. II. To identify mutants defective in arresting phagosome biogenesis and escape into the cytoplasm. III. To characterize the bacterial factors involved in arresting phagosome biogensis and escape into the cytoplasm. Significance: Pathogenesis of the Category A Select Bioterrorism Agent Ft is one of the least studied and understood among intracellular bacterial pathogens. Understanding how this organism exploits macrophages for proliferation and disease manifestation is fundamental to our knowledge of tularemia. The bacterial effectors involved in exploiting the macrophage are potential targets for treatment as well as potential vaccine candidates.