Vaccines Against Ehrlichia and Anaplasma Species Infections

项目总结： 由无浆体科病原体引起的立克次体疾病，包括该属的成员 埃利希氏菌和无浆体在过去30年中日益成为公共卫生问题，并正在 是整个美国和世界许多地区人类扁虱传播感染的主要原因。这个 疾病包括由查菲埃立克体引起的人类单核细胞埃立克体病和粒细胞性埃立克体病 和由无浆体引起的人粒细胞无形体病 吞噬细胞性感染。最初被描述为犬类病原体的犬种E.canis也会引起人的感染。 最近，又发现了另一种壁虱传播的病原菌--鼠埃立克体亚种。据报道，也是引起 人类中的疾病。这些病原体已经进化出逃避宿主免疫的策略，并导致持久 感染。持续感染的人很难诊断，并对血液和器官构成风险 收件人。通过我们最近建立的突变实验，我们创造了查菲埃菲斯突变体 其中包含了导致功能性基因中断的插入片段。ECH_0660基因的插入突变 导致病原体从两种脊椎动物宿主上迅速清除。用该减毒突变株接种疫苗 诱导强烈的宿主反应，并提供全面的抗血流感染和壁虱传播 野生型卡菲埃希氏菌的挑战。我们的进一步研究表明ECH_0660同系物是很好的 在不同的埃利希菌/无浆体物种之间保守。总之，我们广泛的研究形成了强大的 建议项目的基础和前提。在这个提议中，我们将检验衰减的假设 查菲氏乳杆菌ECH_0660基因及其同源物在其他相关基因中的功能缺陷 立克次体将产生安全有效的疫苗，足以防止野生型感染进入 血液流动或壁虱传播；壁虱传播立克次体的两种可能途径 人的感染。我们提出了以下三个具体目标：1)评估免疫持续时间 ECH_0660基因突变减毒活疫苗(MLAV)对野生型感染的挑战 通过血液流动和扁虱传播。2)评估MLAV对遗传差异的保护 查菲乳杆菌菌株。3)鉴定相关埃立克体和无浆体ECH_0660基因同源突变 作为减毒活疫苗对病原体感染的保护作用的物种 进入血液并通过扁虱传播。这些目标是实质性进展的合乎逻辑的延伸 我们已经从我们正在进行的研究中取得了成果。此外，我们还包括了一项严格的实验计划来执行 该项目的目标对推进疫苗的开发至关重要，以预防由 几种重要的硬虱传播的埃立克体和无浆体病原体。我们有高级别的 确保成功执行拟议项目目标所需的专门知识和必要资源。

PROJECT SUMMARY: Rickettsial diseases caused by pathogens of the Anaplasmataceae family, including members of the genera Ehrlichia and Anaplasma, have become a growing public health concern over the past three decades and are a leading cause of tick-borne infections in humans throughout the USA and many parts of the world. The diseases include the human monocytic and granulocytic ehrlichiosis caused by Ehrlichia chaffeensis and Ehrlichia ewingii respectively, and the human granulocytic anaplasmosis resulting from Anaplasma phagocytophilum infections. E. canis, first described as a canine pathogen, also causes infections in people. Recently, another tick-borne pathogen, Ehrlichia muris subsp. eauclairensis, is also reported as causing disease in people. These pathogens have evolved strategies to evade host immunity and cause persistent infections. People with persistent infections are difficult to diagnose and pose risk to blood and organ recipients. Through our recently established mutagenesis experiments, we created E. chaffeensis mutants that contained insertions causing functional gene disruptions. An insertion mutation in the ECH_0660 gene resulted in the pathogen's rapid clearance from two vertebrate hosts. Vaccination with this attenuated mutant induced a strong host response and offered complete against blood stream infection and tick transmission challenges with wild-type E. cahffeensis. Our further studies suggest that the ECH_0660 homologs are well conserved among different Ehrlichia/Anaplasma species. Together, our extensive research forms the strong foundation and premise for the proposed project. In this proposal, we will test the hypothesis that attenuation through a functional deficiency in the E. chaffeensis ECH_0660 gene and its homologs in other related rickettsials will result in safe and efficacious vaccines that are sufficient to prevent wild type infection into the blood stream or from tick transmission; the two possible means by which tick-borne rickettsials cause infections in people. We propose the following three specific aims: 1) Evaluate the duration of immunity offered by the ECH_0660 gene mutant live attenuated vaccine (MLAV) against wild type infection challenge through blood stream and tick-transmission. 2) Evaluate the protection of the MLAV against genetically distinct E. chaffeensis strains. 3) Evaluate ECH_0660 gene homolog mutants in related Ehrlichia and Anaplasma species for their efficacy as live attenuated vaccines in conferring protection against the pathogens' infection into blood stream and by tick-transmission. The goals represent a logical extension of the substantial progress we have made from our ongoing research. Further, we have included a rigorous experimental plan to execute the project goals, which are critical in advancing the development of vaccines to prevent diseases caused by several important tick-transmitted Ehrlichia and Anaplasma species pathogens. We have the high-level expertise and the necessary resources to ensure the successful execution of the proposed project goals.