Molecular Mechanisms of msp2 Variation in Rickettsiae

这项建议的目的是为了提高我们对壁虱致病机制的认识。 引起人和动物埃立克次体病和无浆体病的立克次体病原体。这些 病原体有效地利用小基因组(1.5Mb)来逃避免疫反应并建立 持续感染哺乳动物宿主，在硬蜱中肠和唾液中定植和复制 并在重新摄食扁虱时产生传染性，以实现进一步传播。MSP2是 最初在边缘无浆体中定义，以及牛和扁虱感染这种病原体提供了一种 发现用于修饰表面蛋白质组的机制的极佳模型。在先前的项目中 期间，我们确定了MSP2的单个表达位点的节段性基因转化，以及相关的表面 并列MSP3，作为产生表面多样性的主要机制，并显示出差异 哺乳动物宿主与TICK载体之间操纵子编码蛋白的表达。一个相似的基因 无浆体吞噬细胞利用转换机制表达大量的外膜蛋白 人类患者的膜蛋白和其他人的研究支持从多个基因座到 产生表面多样性。对边缘毛囊线虫基因组的分析揭示了一个复杂的外源基因家族 与msp2相关的膜蛋白基因。这个MSP2超家族由32个对白组成， 包括两个msp2和msp3操纵子连接的表达位点、单个msp4基因座、多个msp2 和msp3伪基因，以及其他未鉴定的msp2-1类同源基因。我们假设这一差异 这些类似物的表达和它们之间的重组产生了病原体的多样性 表面，并提供生物体适应和持久存在于不同宿主和细胞中的能力 环境。本提案的具体目的是：1]确定msp2超家族基因是否 在哺乳动物和无脊椎动物宿主感染期间的差异表达；2]确定操纵子 Msp2超家族基因簇内多样性的结构和产生；3]确定 哺乳动物和无脊椎动物宿主中msp2超家族蛋白的差异调控；和4] 比较边际灵芝和灵芝中msp2超家族蛋白的表达调控。 吞噬细胞性。

The objective of this proposal is to improve our understanding of the mechanisms of pathogenesis of tick- borne rickettsial pathogens that cause ehrlichiosis and anaplasmosis of humans and animals. These pathogens efficiently utilize a small genome (<1.5 Mb) to evade the immune response and establish persistent infection in the mammalian reservoir host, to colonize and replicate in the tick midgut and salivary glands, and to develop infectivity upon renewed feeding of the tick to effect onward transmission. MSP2 was initially defined in Anaplasma marginale and infections of cattle and ticks with this pathogen provide an excellent model for discovering the mechanisms used to modify the surface proteome. In the prior project period, we identified segmental gene conversion of single expression sites for MSP2, and a related surface paralogue MSP3, as a primary mechanism for generating surface diversity and demonstrated differential expression of operon-encoded proteins between the mammalian host and tick vector. A similar gene conversion mechanism is used by Anaplasma phagocytophilum to express a large repertoire of outer membrane proteins in human patients and studies by others support expression from multiple loci to generate surface diversity. Analysis of the A. marginale genome reveals a complex family of outer membrane protein genes related to msp2. This msp2 superfamily is comprised of 32 paralogues, comprising the two msp2 and msp3 operon-linked expression sites, a single msp4 gene locus, multiple msp2 and msp3 pseudogenes, and other uncharacterized msp2-1ike paralogues. We hypothesize that differential expression of these paralogues and recombination between them generates diversity in the pathogen surface and provides the ability of organisms to adapt to and persist in different hosts and cellular environments. The specific aims of the present proposal are: 1] Determine if msp2 superfamily genes are differentially expressed during infection of the mammalian and invertebrate hosts; 2] Determine the operon structure and generation of diversity within msp2 superfamily gene clusters; 3] Identify the mechanisms for differential regulation of the msp2 superfamily proteins in the mammalian and invertebrate hosts; and 4] Compare regulation of expression of msp2 superfamily proteins in A. marginale and A. phagocytophilum.