A CD8+ T cell Diagnostic to Identify Children with Pulmonary Tuberculosis

描述(由申请人提供)：结核病(TB)是由结核分枝杆菌(Mtb)感染引起的疾病，是全球5岁儿童感染性发病率和死亡率的主要原因。在结核病流行地区，世界上每年900万成人结核病病例中的绝大多数居住在这些地区，5岁以下的儿童占患者总数的30%-40%，这些被感染的儿童往往患有更严重的、往往是致命的结核病。5岁儿童结核病致死率的一个重要因素是这个年龄段的标准结核病诊断表现不佳，特别是与成年人相比。糟糕的诊断会导致延迟和漏诊，进而导致儿童发病率和死亡率的增加。目前，需要的是一种简单、强大的免疫诊断测试，将儿童肺结核病与非结核病肺炎区分开来。我们推测，针对结核分枝杆菌多肽的CD8+T细胞的检测可以用于区分儿童肺结核肺炎和非肺结核肺炎。在这方面，CD8+T细胞优先识别严重感染结核分枝杆菌的细胞，我们在乌干达5岁儿童中观察到，在结核病儿童中检测到具有结核分枝杆菌反应性的CD8+T细胞，而在感染/接触结核杆菌的无症状儿童中未检测到。综上所述，这些数据表明CD8+T细胞与细菌负荷有关。同时，我们通过我们的大规模抗原发现计划定义了45种免疫优势、经临床验证的CD8结核抗原，这些抗原从OHSU独家授权给Viti，Inc.。为了开发一种改进的、被广泛认可的诊断方法，我们计划使用生物信息学方法来定义这45个免疫显性CD8抗原中可能包含免疫原性表位簇的多肽。这些肽将被单独筛选，以供CD8+T细胞识别，这些细胞来自不同种族的潜伏性结核病感染(LTBI)成年人或未感染的成年人。在迭代过程中，我们将选择多肽集合以包含三个肽库；一个针对敏感性进行优化，一个针对特异性进行优化，另一个针对结核分枝杆菌感染的敏感性和特异性进行平衡。在未来的第二阶段SBIR应用中，这三个肽库将被评估为儿童结核病肺炎的免疫诊断，这项研究将比较患有结核病肺炎的乌干达和越南儿童与非结核病肺炎儿童的CD8+T细胞反应。 公共卫生相关性：结核病(TB)是导致全球儿童传染病发病率和死亡率的最重要原因之一。幼儿更有可能患上由结核分枝杆菌(Mtb)引起的严重疾病。此外，儿童结核病肺炎很难诊断，导致延误和漏诊，进一步增加了发病率和死亡率。这些研究的目的是开发一种简单、强大的免疫诊断测试，以区分幼儿中的结核病肺炎和非结核病肺炎。

DESCRIPTION (provided by applicant): Tuberculosis (TB) disease, which results from infection with Mycobacterium tuberculosis (Mtb), is a leading cause of infectious morbidity and mortality in children < 5 years old worldwide. In TB endemic regions, in which the vast majority of the world's annual 9 million adult cases of TB disease reside, children < 5 years old account for 30-40% of the total patients and those children who are infected tend to have more severe, often fatal forms of TB. A significant contributor to the deadliness of TB in children < 5 years old is the poor performance of standard TB diagnostics in this age group, especially as compared to adults. Poor diagnostics result in delayed and missed diagnoses, which in turn lead to increased morbidity and mortality in children. Currently, what is needed is a simple, robust immunodiagnostic test that will differentiate childhood pulmonary TB from non-TB pneumonia. We hypothesize that the detection of CD8+ T cells directed toward Mtb peptides can be utilized to distinguish young children with TB pneumonia from those with non-TB pneumonia. In this regard, CD8+ T cells preferentially recognize heavily Mtb-infected cells and we have observed in Ugandan children < 5 years old, that Mtb-reactive CD8+ T cells are detected in children with TB and not detected in asymptomatic children with Mtb infection/exposure. Taken together, these data suggest that CD8+ T cells correlate with bacterial burden. In parallel, we have defined 45 immunodominant, clinically- validated CD8 TB antigens through our large scale antigen discovery program that are exclusively licensed to ViTi, Inc. from OHSU. To develop an improved, broadly recognized diagnostic, we plan to use a bioinformatic approach to define peptides within these 45 immunodominant CD8 antigens likely to contain clusters of immunogenic epitopes. These peptides will be screened individually for recognition by CD8+ T cells from ethnically diverse adults with latent TB infection (LTBI) or uninfected adults. In an iterative process, we will select sets of peptides to comprise three peptide pools; one optimized for sensitivity, one for specificity, and one for a balance of sensitivity and specificity for Mtb infection. For a future Phase II SBIR application, these three peptide pools will be evaluated as an immunodiagnostic for TB pneumonia in children in a study comparing CD8+ T cell responses of Ugandan and Vietnamese children with TB pneumonia to those with non- TB pneumonia. PUBLIC HEALTH RELEVANCE: Tuberculosis (TB) is one of the most important causes of infectious morbidity and mortality in children worldwide. Young children are more likely to develop severe disease from the causative agent Mycobacterium tuberculosis (Mtb). Moreover, childhood TB pneumonia is difficult to diagnose resulting in delayed and missed diagnoses, further contributing to morbidity and mortality. The purpose of these studies is to develop a simple, robust immunodiagnostic test that distinguishes TB pneumonia from non-TB pneumonia in young children.