TB Diagnosis Based on Promiscuous PE-PGRS Epitopes

描述(由申请人提供)：为抗击肆虐的结核病流行，迫切需要一种简单、敏感和特定的护理点检测，可以在艾滋病毒携带者和HIV+受试者中诊断结核病。在结核分枝杆菌(复合体)中存在一个称为PE-PGRS基因的亚家族，但在其他几种常见的分枝杆菌病原体中不存在PE-PGRS基因，包括感染5-7%的HIV阳性患者的禽分枝杆菌和麻风分枝杆菌。这使得PE-PGRS蛋白成为结核病诊断测试的有吸引力的目标。我们的初步研究表明，几种PE-PGRs蛋白共有的免疫优势表位(混杂表位)在结核病患者中具有高度的免疫原性。基于这些结果，我们建议鉴定在结核分枝杆菌临床分离株气溶胶感染的结核病兔肺中高表达的PE-PGRs基因，并绘制其免疫显性混杂表位图，该表位可被HIV-TB+和HIV+TB+患者的抗体特异性识别。这些表位可以作为一种简单的基于多肽的结核病诊断试验的基础。具体地说，我们建议：a)鉴定结核分枝杆菌在肺部生长和复制过程中高表达的PE-PGRs基因亚集，并对其蛋白质进行表征(目标1)；B)剖析目标1中选择的PEPGRS蛋白，以描绘免疫优势表位，这些表位可被来自HIV-TB+和HIV+TB+患者的血清抗体识别，但不能被接种PPD-、PPD+和/或卡介苗的健康受试者或HIV+TB对照人员识别(目标2)；以及c)评估目标2中确定的表位与不同结核病不同阶段患者的血清的反应性，以确定最佳的多肽集合，并评估与来自不同地理环境的患者的血清反应的最佳多肽亚组(目标3)。与公共卫生相关：拟议的工作可能导致开发一种廉价、可靠和快速的结核病诊断检测方法。到目前为止，还没有可靠的结核病快速检测方法，这将是该领域的一项重大进步。

DESCRIPTION (provided by applicant): A simple sensitive and specific point-of-care test that can diagnose TB in both HIV- and HIV+ subjects is urgently needed for combating the raging TB epidemic. A subfamily of genes, called PE-PGRS genes is present in M. tuberculosis (complex), but there are no PE-PGRS genes in several other common mycobacterial pathogens including M. avium (which afflicts 5-7% of the HIV+ subjects) and M. leprae. This makes the PE-PGRS proteins attractive targets for inclusion into diagnostic tests for TB. Our preliminary studies demonstrate that immunodominant epitopes that are shared by several PE-PGRS proteins (promiscuous epitopes) are highly immunogenic in TB patients. Based on these results we propose to identify the PE-PGRS genes that are highly expressed in the lungs of tuberculous rabbits infected with aerosols of clinical isolates of M. tuberculosis, and map their immunodominant promiscuous epitopes recognized specifically by antibodies from HIV-TB+ and HIV+TB+ patients. These epitopes can be the basis of a simple peptide-based diagnostic test for TB. Specifically, we propose to: a) Identify the subset of PE-PGRS genes that is highly expressed by M. tuberculosis during growth and replication in lungs, and characterize the proteins (Aim #1); b) Dissect the PEPGRS proteins selected in Aim # 1 to delineate the immunodominant epitopes that are recognized by serum antibodies from HIV-TB+ and HIV+TB+ patients but not by PPD-, PPD+ and/or BCG vaccinated healthy subjects or HIV+TB- controls (Aim #2) and c) Evaluate the reactivity of epitopes identified in Aim #2 with sera from individual patients at different stages of TB to identify the optimal set of peptides and evaluate the optimal peptide-subset for reactivity with sera from patients from different geographical settings (Aim # 3). PUBLIC HEALTH RELEVANCE: The work proposed could lead to development of a cheap, reliable and rapid diagnostic test for TB. No reliable rapid tests for TB exist so far and this would be a major advancement in the field.