Identification of rikettsial antigens for vaccine development

普氏立克次体是人类已知的最致命的细菌病原体之一， 军队和武器。它是一种B类生物威胁选择剂，因为它可以通过 气溶胶、感染剂量低、稳定性高、致病性强、病死率高。的 开发交叉反应疫苗是可行的，因为自然立克次体感染提供了保护性， 流行性斑疹伤寒幸存者（以及鼠）的免疫力，因为交叉保护已经被 实验证明，尽管如此，安全有效的疫苗并不存在，因为我们 对保护的免疫相关性的不完全理解，并且因为保护性抗原 仍然身份不明因此，本申请的目的是发现交叉保护性立克次体抗原 由T和B淋巴细胞识别。我们假设基于交叉反应的亚单位疫苗 立克次体抗原将保护小鼠和一种新的人源化小鼠模型免受致命的同源和 异源立克次体挑战。这项研究将有助于实现发展的长期目标， 用于人类抵抗立克次体的免疫增强剂。全基因组方法的五个具体目标 将解决的假设：1）确定免疫相关的保护立克次体感染; 2） 鉴定由CD 8 + T淋巴细胞识别的新的MHC I类限制性交叉反应性立克次体抗原; 3） 鉴定由CD 4 + T淋巴细胞识别MHC II类限制性交叉反应性立克次体抗原; 4） 鉴定被抗立克次体抗体识别的交叉反应性立克次体抗原;和5）确定 亚单位疫苗对立克次体致命攻击的保护作用。第一个目标将提供 保护的免疫相关性的关键定义，这将指导选择和评估 疫苗接种方案。目的2、3和4将通过系统的免疫学方法鉴定立克次体T细胞和B细胞抗原。 对所有R. prowazekii基因。第五个目标是确定疫苗配方和疫苗接种 该方案将提供持久的多功能和交叉反应性保护性免疫应答。在这 我们的研究直接涉及WRCE的战略计划和NIAID的生物防御研究议程。的 本研究的创新之处在于系统地界定了免疫保护的相关因素， 通过全面的基因组筛选，多种疫苗配方的测试， 以及使用具有重建的功能性人免疫系统的高度相关的小鼠模型。

Rickettsia prowazekii is one of the most lethal bacterial pathogens known to man; it has decimated entire armies and has been weaponized. It is a category B biothreat select agent because of transmissibility by aerosol, low infectious dose, high stability, and causation of severe illness with a high case-fatality ratio. The development of a cross-reactive vaccine is feasible because natural rickettsial infection provides protective immunity in survivors of epidemic (as well as murine) typhus, and because cross-protection has been demonstrated experimentally; nevertheless, safe and effective vaccines do not exist because of our incomplete understanding of the immune correlates of protection, and because the protective antigens remain unidentified. Thus, the objective of this application is to discover cross-protective rickettsial antigens recognized by T and B lymphocytes. We hypothesize that a subunit vaccine based on cross-reactive rickettsial antigens will protect mice, and a novel humanized mouse model, from lethal homologous and heterologous rickettsial challenges. This investigation will contribute to the long-term goal of developing immunotherapeutic agents for humans against rickettsiae. Five specific aims with genome-wide approaches will address the hypothesis: 1) identify immunological correlates of protection against rickettsial infection; 2) identify new MHC class l-restricted cross-reactive rickettsial antigens recognized by CD8+ T lymphocytes; 3) identify MHC class ll-restricted cross-reactive rickettsial antigens recognized by CD4+ T lymphocytes; 4) identify cross-reactive rickettsial antigens recognized by anti-rickettsial antibodies; and 5) determine the protection conferred by a subunit vaccine against a lethal challenge with Rickettsia. The first aim will provide critical definitions of immune correlates of protection that will guide the selection and evaluation of vaccination protocols. Aims 2, 3, and 4 will identify rickettsial T cell and B cell antigens through a systematic evaluation of all R. prowazekii genes. The fifth aim will identify a vaccine formulation and vaccination protocol that will provide a durable multifunctional and cross-reactive protective immune response. In this way, our research directly addresses WRCE's strategic plan and NIAID's Biodefense Research Agenda. The innovation of this research lies in the systematic definition of immune correlates of protection, the discovery of rickettsial antigens through a comprehensive genomic screen, the testing of multiple vaccine formulations, and the use of a highly relevant mouse model with a reconstituted functional human immune system.