Host-derived biomarker signatures for the diagnosis of acute rickettsial diseases

立克次体疾病，如斑点热群立克次体（SFGR）和恙虫病引起的疾病 (ST)据估计，全球每年有数百万人因此患病。SFGR感染影响退伍军人和 其他成员的公众在整个美国，和SFGR和丛林斑疹伤寒都是持续的威胁， 驻扎在世界各地的现役战士。有效的治疗是存在的，但目前没有临床上 能够在指导所需的时间范围内产生可靠诊断信息的可用测试 治疗决定。通过这一建议，我们打算探索自然人类感染的病理生理学 与主机响应定义的SFGR和ST，并利用此信息生成实际测试 能够在急性情况下诊断这些疾病先前发表的工作和我们的初步数据表明， 这些立克次体感染触发了人类宿主中保守的炎症途径，正是这些独特的 我们将利用这些宿主反应来鉴定循环白色血液中的基因表达模式 在发热患者中识别这些微生物存在的细胞。为了生成这样的“签名”， 感染，该项目将利用两个主要临床队列的独特组合。第一组是由 美国退伍军人与急性立克次体病诊断在这里在美国，都以前登记的急性 SFGR感染以及正在招募的新病例。第二组由现有的大型 从世界各地招募的患有各种急性发热性SFGR感染的个体样本集 与恙虫病一样，我们已经证明它模仿了SFGR感染中的宿主反应。这种组合 将使我们有能力产生立克次体基因签名， 在美国，以及有潜力的效用超越我们的边界，为旅客和现役军人 派驻国际的成员。我们将利用RNA测序（RNASeq）来识别复杂的模式， 来自患有其他类型发热性疾病的受试者和对照者的外周血样品中的基因表达 （包括来自美国和全球的病毒和细菌感染）。然而，高维RNASeq 分析不是能够在临床相关时间范围内产生诊断答案的模态。所以我们 将“修剪”这些复杂的签名，使其成为适合于RT-PCR平台的更小的基因组分类器， 因为使用RT-PCR探针既适用于现有的临床实验室基础设施， 正在开发中的快速护理点平台，从而开始了进行此类测试的最后步骤 达到临床实用的程度。因此，通过这项建议，我们打算探索的病理生理学， 自然人感染SFGR和恙虫病，如宿主反应所定义的，并利用这一点， 信息来构建具有诊断能力的基于系统的模型。因此，我们期望，不仅 这些实验是否能为我们提供关于宿主反应的一个基本上未被探索的方面的令人兴奋的新数据 但他们将为将这些发现转化为实际应用奠定基础。 对公众和退伍军人健康有直接影响的应用。

Rickettsial diseases such as those caused by Spotted Fever Group rickettsii (SFGR) and Scrub typhus (ST) are estimated to account for millions of illnesses a year worldwide. SFGR infections affect Veterans and other members of the public throughout the US, and both SFGR and Scrub typhus are continuous threats to active duty warfighters stationed throughout the world. Effective therapy exists, but there is currently no clinically available test capable of yielding reliable diagnostic information within the timeframe required to guide therapeutic decisions. Through this proposal we intend to explore the pathophysiology of natural human infection with SFGR and ST as defined by the host response, and to utilize this information to generate a practical test capable of diagnosing these diseases in the acute setting. Prior published work and our preliminary data suggest that these rickettsial infections trigger conserved inflammatory pathways in human hosts, and it is these unique host responses that we will harness in order to identify patterns of gene expression within circulating white blood cells that identify the presence of these organisms in febrile patients. In order to generate such a ‘signature’ of infection, this project will utilize a unique combination of two main clinical cohorts. The first cohort is made up of US Veterans with acute rickettsial illness diagnosed here in the US, both previously enrolled patients with acute SFGR infection as well as ongoing enrollment of new cases. The second cohort is made up of a large existing sample set of individuals enrolled from around the world with a variety of acute febrile SFGR infections as well as Scrub typhus, which we have shown mimics the host responses seen in SFGR infection. This combination will give us the ability to generate a rickettsial gene signature that both identifies acute disease in Veterans here in the US as well as having the potential for utility beyond our borders for travelers and active duty military members stationed internationally. We will utilize RNA Sequencing (RNASeq) to identify complex patterns of gene expression in peripheral blood samples from subjects and controls with other types of febrile illnesses (including viral and bacterial infections, both from the US and globally). However, high dimensional RNASeq analysis is not a modality that can produce diagnostic answers in a clinically relevant timeframe. Therefore, we will ‘prune’ these complex signature(s) down to smaller genomic classifiers appropriate for RT-PCR platforms, as using RT-PCR probes lends itself to both existing clinical laboratory infrastructure as well as to a number of burgeoning point-of-care platforms in development, thus beginning the final steps towards bringing such a test to the point of actual clinical utility. Thus, through this proposal we intend to explore the pathophysiology of natural human infection with SFGR and Scrub typhus as defined by the host response, and to utilize this information to build systems-based models with diagnostic capability. It is therefore our expectation that not only will these experiments provide us with exciting new data about a largely unexplored aspect of the host response to infections with true global impact, but that they will lay the foundation for translating these findings into practical applications with a direct impact on public and Veteran health.