TB Diagnosis Based on Promiscuous PE-PGRS Epitopes

描述（由申请人提供）：为了对抗肆虐的结核病流行，迫切需要一种简单、敏感和特异性的即时检测方法，可以在艾滋病毒感染者和艾滋病毒感染者中诊断结核病。一个被称为PE-PGRS基因的基因亚家族存在于结核分枝杆菌（复合体）中，但在其他几种常见的分枝杆菌病原体中没有PE-PGRS基因，包括鸟分枝杆菌（感染5-7%的HIV+患者）和麻风分枝杆菌。这使得PE-PGRS蛋白成为纳入结核病诊断检测的有吸引力的靶标。我们的初步研究表明，由多个PE-PGRS蛋白共享的免疫显性表位（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，我们提出在感染临床分离结核分枝杆菌气溶胶的结核家兔的肺中鉴定高表达的PE-PGRS基因，并绘制它们的免疫优势混杂表位，这些表位可被HIV-TB+和HIV+TB+患者的抗体特异性识别。这些表位可以作为简单的基于肽的结核病诊断试验的基础。具体来说，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度表达的PE-PGRS基因亚群，并表征这些蛋白（Aim #1）；b)解剖Aim # 1中选择的PEPGRS蛋白，以描述HIV-TB+和HIV-TB+患者血清抗体可识别但PPD-不能识别的免疫显性表位；PPD+和/或BCG疫苗接种的健康受试者或HIV+结核病对照者（目标2）和c)评估目标2中鉴定的表位与不同结核病阶段个体患者血清的反应性，以确定最佳肽集，并评估最佳肽亚群与来自不同地理环境的患者血清的反应性（目标3）。公共卫生相关性：提出的这项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.