Vector and Host Contributions to the Regulation of E. chaffeensis Gene Expression

项目摘要： 由埃立克体属和无形体属的蜱传立克次体引起的疾病一直在增加， 近年来健康问题。这些疾病包括人类单核细胞埃立克体病、人类粒细胞性埃立克体病、人类淋巴细胞性埃立克体病、人类淋巴细胞性埃立克体病、人类淋巴细胞性埃立克体病、人类淋巴细胞性埃立克体病和人类淋巴细胞性埃立克体病。 查菲埃立克体、埃立克体引起的埃立克体病和人粒细胞无形体病;埃温吉和 嗜吞噬细胞无形体。尽管节肢动物的细胞环境复杂， 脊椎动物具有复杂的防御系统，立克次氏体进化出逃避宿主的策略 间隙例如，E.巨噬细胞和蜱细胞中的chaffeensis在形态上显著不同 具有不同的蛋白质表达模式。表达模式包括来自 p28-Omp多基因位点，包含22个基因。p28 Omp基因的表达主要受 p28-Omp基因19，而在蜱细胞中表达的抗原主要来自 p28-Omp基因14.我们的研究还表明，在脊椎动物和蜱中的差异表达 细胞导致宿主反应改变，例如脊椎动物宿主对蜱细胞来源的 E. chaffeensis相比，巨噬细胞来源的细菌。本研究将侧重于基本的 了解p28-Omp多基因位点的基因表达调控。核心假设 本研究的一个重要结果是，p28-Omp基因在E. chaffeensis在以下方面受到差异调节： 对环境信号的反应，以及宿主细胞特异性基因表达对病原体的生长至关重要。 在脊椎动物和蜱细胞环境中存活。本研究的具体目的是：1）建立体外 用于定位埃里希体启动子的转录和翻译系统，2）定位埃里希体启动子中的转录机制， p28-Omp基因座的差异表达基因14和19，3）评估巨噬细胞的贡献 和蜱细胞环境，用于基因14和19的差异表达，和4）评估敲除 p28-Omp基因14和19的突变，以评估宿主细胞特异性表达的生物学相关性。 本研究结果将为深入了解E. chaffeensis基因调控 以及巨噬细胞和蜱细胞中的立克次氏体如何对差异表达的缺失做出反应， 表达的蛋白质。

PROJECT ABSTRACT: Illnesses caused by the tick-borne rickettsiales of the genera Ehrlichia and Anaplasma have been a growing health concern in recent years. These illnesses include human monocytic ehrlichiosis, human granulocytic ehrlichiosis and human granulocytic anaplasmosis which are caused by Ehrlichia chaffeensis, E. ewingii and Anaplasma phagocytophilum, respectively. Despite the complex cellular environment of arthropods and vertebrates having sophisticated systems of defense, the rickettsiales evolved strategies to evade host clearance. For example, E. chaffeensis in macrophages and tick cells differ significantly in their morphology with distinct patterns of protein expression. The expression patterns include the differential expression from the p28-Omp multigene locus which contains 22 genes. The p28 Omp gene expression is restricted primarily to the p28-Omp gene 19 in macrophages, whereas in tick cells the expressed antigen is predominantly from the p28-Omp gene 14. Our studies also demonstrate that the differential expression in vertebrate and tick cells contributes to the altered host response, such as the delayed clearance in a vertebrate host for tick cellderived E. chaffeensis compared to that for macrophage-derived bacteria. This study will focus on the basic understanding of the regulation of gene expression from the p28-Omp multigene locus. The central hypothesis of this study is that the transcription from the p28-Omp locus in E. chaffeensis is differentially regulated in response to environmental signals and that the host cell-specific gene expression is essential for pathogen¿s survival in vertebrate and tick cell environments. Specific aims of this study are; 1) establish in vitro transcription and translation system for mapping Ehrlichia promoters, 2) map transcriptional machinery in differentially expressed genes 14 and 19 of the p28-Omp locus, 3) evaluate the contributions of macrophage and tick cell environments for differential expression from genes 14 and 19, and 4) evaluate knockout mutations for the p28-Omp genes 14 and 19 to assess the biological relevance of host cell specific expression. The results from this study will provide important information for understanding E. chaffeensis gene regulation and how the rickettsiale in macrophages and tick cells respond to the loss of expression from a differentially expressed protein.