Murine Typhus: Vector Biology and Transmission

描述（由申请人提供）：我们提出的研究强调了几个主要概念，如立克次体毒力问题，立克次体在不同脊椎动物和无脊椎动物宿主中的适应性，以及病原体-宿主（跳蚤/大鼠）相互作用的分子动力学。在这个竞争性的更新应用中，我们建立在最近的成就上，现在专注于解剖定义鼠斑疹伤寒人畜共患病的分子相关性。因此，我们将使用一个综合的方法，包括立克次体基因组数据挖掘，病原体的基因组分析和实证研究相结合，调查立克次体和宿主转录组谱的模式，并确定是否主机关联指导立克次体毒力的程度。本研究的目的是：（1）确定跳蚤免疫反应蛋白是否限制了R.伤寒沙门氏菌（Aim I）和（2）功能上表征一组立克次体基因，这些基因被鉴定为在毒力中具有潜在作用（Aim II）。该提案的具体目标旨在强调宿主和伤寒立克次体为确保自身生存而采用的策略。在目标I下，我们将测试跳蚤免疫应答蛋白限制R的假设。伤寒生长。暗示了R.伤寒和每种免疫应答蛋白的体内、免疫学、生物化学和分子方法将用于证明每种免疫应答蛋白的共定位和抗立克次体性质。此外，RNAi将用于确定免疫基因表达的抑制是否影响立克次体的体内生长。根据第二个目标，我们将测试的假设，分泌蛋白质在立克次体毒力发挥了重要作用。为了评估这一假设，我们将利用一个综合的方法，包括全基因组鉴定和分子分析的R。伤寒杆菌分泌蛋白的研究以及利用反义RNA技术对筛选出的潜在毒力基因进行功能分析。项目叙述：鼠伤寒就是一个很好的例子，它的重要性只有病人才能充分认识到，即使在今天，在世界上的大多数地方，病人也永远不知道自己患了什么病，因为诊断不出来。鼠（地方性）斑疹伤寒的病原体、斑疹伤寒立克次体、老鼠及其跳蚤之间的密切联系是随着农村地区城市化程度的提高，这种疾病向农村社区蔓延的基础。因此，R.伤寒不仅由于卫生条件松懈而在世界许多沿海地区重新出现，而且还成为农村动物种群中的一种新的病原体。我们的研究强调了几个主要的概念，立克次体毒力和发病机制，通过使用鼠斑疹伤寒动物模型。我们的研究促进了对R.通过提供关于病原体基因产物的信息，可用于开发更好的立克次体疫苗和/或治疗方法，

DESCRIPTION (provided by applicant): Our proposed research underscores several major concepts such as the issue of rickettsial virulence, rickettsial fitness in diverse vertebrate and invertebrate hosts, and molecular dynamics of pathogen-host (flea/rat) interactions. In this competing renewal application, we build upon recent accomplishments, and now focus on dissecting the molecular correlates that define the murine typhus zoonosis. Thus, we will use an integrated approach including the combination of rickettsial genome data mining, pathogen phylogenomic analysis and empirical studies to investigate the patterns of rickettsial and host transcriptome profiles and to define whether host-association directs the degree of rickettsial virulence. The aims of this competitive renewal is to (1) determine if flea immune response proteins limit the growth of R. typhi (Aim I) and (2) functionally characterize a set of rickettsial genes that were identified as having a potential role in virulence (Aim II). The specific aims of the proposal are designed to highlight the strategies employed by both the host and the Rickettsia typhi to ensure their own survival. Under the aim I, we will test the hypothesis that flea immune responsive proteins limit R. typhi growth. To implicate an interaction between R. typhi and each immune responsive protein in vivo, immunological, biochemical and molecular approaches will be used to demonstrate colocalization and anti-rickettsial properties of each immune responsive protein. Additionally, RNAi will be used to determine if suppression of immune gene expression affects rickettsial growth in vivo. Under the second aim we will test the hypothesis that secretory proteins play a cardinal role in rickettsial virulence. In order to assess this hypothesis, we will utilize an integrated approach that includes a genome-wide identification and molecular analysis of R. typhi secretory proteins and functional analysis of selected potential virulence genes by anti-sense RNA technology. PROJECT NARRATIVE: Murine typhus is a good example of a disease whose importance is not adequately appreciated except by the patient, and, even today, in most parts of the world, he will never know what ails him because the diagnosis will not be made. An intimate association between the causative agent of murine (endemic) typhus, Rickettsia typhi, rats and their fleas underlie the expansion of this disease into rural communities as the urbanization of rural settings is on the increase. Thus, R. typhi not only re-emerge in many coastal regions of the world as a result of relaxed hygiene but also become an emerging pathogen in rural animal populations. Our proposed research underscores several major concepts in rickettsial virulence and pathogenesis by using murine typhus animal model. Our research advances the understanding the biology of R. typhi by providing information on pathogen gene products that could be used in developing better rickettsial vaccines and/or therapeutics.