Mechanisms of Mycobacterial Antigen Processing

描述（申请人提供）：结核病是一种对人类影响巨大的全球性疾病。每年死于肺结核的人数多于死于其他疾病的人数。现有的卡介苗对儿童有部分保护作用，对成人疾病无效。我们已经确定，导致BCG疫苗效力降低的一个主要因素是其阻止巨噬细胞中有效抗原加工的能力。我们还发现，从结核分枝杆菌（？fbpA）比BCG更好地保护小鼠。因此，这项研究将使用这种候选疫苗，并测试树突状细胞中改进的“肽抗原加工”将为开发更有效的结核病疫苗铺平道路的假设。由于吞噬体成熟停滞，BCG疫苗的结构抗原保持隔离在吞噬体内，而其分泌的抗原被最低限度地加工成MHC-II和MHC-I肽表位。相比之下，？fbpA新疫苗经历有限的吞噬体成熟，具有增强的MHC-II途径的肽呈递，并且我们假设它也通过MHC-I机制呈递肽。与目前使用的BCG疫苗不同，？fbpA具有完整的ESAT-6和CFP-10蛋白，我们将通过选择性缺失基因以及过表达ESAT-6、Ag 85 B和CFP-10抗原来修饰病原体组分，从而增强抗原性。因此，我们将确定病原体的组成部分，引发保护性免疫反应相关的疫苗设计和制备新的疫苗构建体，通过基因工程提高免疫原性和安全性。这项建议的主要目标是开发一个吞噬体成熟主管衍生物？fbpA疫苗，其预期被树突细胞更有效地加工以呈递比先前疫苗更多的免疫原性肽。目的是- I）研究增加免疫原性的细胞内策略？fbpA候选疫苗通过增强MHC-II肽的呈递，和II）表征MHC-I肽，所述MHC-I肽增加fbpA候选疫苗的免疫原性。fbpA候选疫苗。

DESCRIPTION (provided by applicant): Tuberculosis is a global disease of immense impact on mankind. More people die of tuberculosis each year than due to other diseases. The available BCG vaccine is partially protective against children and is not effective against adult disease. We have determined that one major factor that contributes to the reduced efficacy of BCG vaccine is its ability to prevent effective antigen processing in macrophages. We also discovered that a mutant vaccine from Mycobacterium tuberculosis (?fbpA) protects mice better than BCG. This investigation will therefore use this candidate vaccine and test the hypothesis that improved 'peptide antigen processing' in dendritic cells will pave the way for development of a more effective vaccine against tuberculosis. Due to phagosome maturation arrest, structural antigens of BCG vaccine remain sequestered within phagosomes while its secreted antigens are minimally processed for MHC-II and MHC-I peptide epitopes. In contrast, ?fbpA novel vaccine undergoes limited phagosome maturation, with enhanced peptide presentation for MHC-II pathway and we hypothesize that it also presents peptides through MHC-I mechanism. Unlike the currently used BCG vaccine, ?fbpA has intact ESAT-6 and CFP-10 proteins and we will enhance antigenicity by modification of pathogen components through selective deletion of genes as well as over expression of ESAT-6, Ag85B and CFP-10 antigens. We will therefore identify pathogen components that elicit protective immune responses relevant to vaccine design and prepare novel vaccine constructs through genetic engineering with increased immunogenicity and safety. The major goal of this proposal is to develop a phagosome maturation competent derivative of ?fbpA vaccine that is expected to be more efficiently processed by dendritic cells to present more immunogenic peptides than previous vaccines. The aims are to- I) Investigate the intracellular strategies that increase the immunogenicity of ?fbpA candidate vaccine by enhancing the presentation of MHC-II peptides, and II) Characterize the MHC-I peptides that increase the immunogenicity of ?fbpA candidate vaccine.