Pathways of Antigen Presentation to CD8 T Cells In Vivo

描述（由申请方提供）：CD 8 + T细胞是针对某些病毒的抗病毒免疫应答的关键组分。初始CD 8 + T细胞仅在识别抗原呈递细胞（APC）表面上的肽-MHC I类复合物后才分化为效应细胞。呈递的肽可以通过体内的许多途径由蛋白质抗原产生。当呈递被称为直接引发时，肽可以从病毒感染的APC内表达的抗原产生。或者，肽可以由在呈递之前从其他细胞转移到APC的蛋白质产生，这一过程称为交叉引发。直接致敏或交叉致敏在多大程度上有助于体内初始CD 8 + T细胞的活化尚不清楚。本项目的总体目标是描述用于在体内初始CD 8 + T细胞引发期间产生MHC I类肽复合物的机制。我们的基本假设是，蛋白质表达的改变可以，并且确实，直接在体内抗原呈递到直接或交叉引发途径。为了研究这个问题，我们将使用重组病毒表达多种蛋白抗原，并将分析抗原呈递给幼稚和效应CD 8 + T细胞在体外和体内。在目的1中，我们将确定在特定组织中表达的靶向病毒抗原对体内使用的抗原呈递途径的影响。我们将研究CD 8 + T细胞引发遍在表达或组织靶向抗原的时间和效率。我们还将确定负责通过每种途径启动的APC，并检查有效启动所需的APC特性。在目标2中，我们将研究差异抗原呈递作为病毒生命周期后期表达的病毒基因的免疫原性降低的机制。此外，通过使用穿梭进入体内不同抗原呈递途径的抗原的天然实例，我们将比较经由直接或交叉致敏的CD 8 + T细胞致敏的效率与体内制备的抗原的量。在目标3中，我们将在体外和体内确定在交叉引发期间优先从病毒感染的细胞转移到APC的蛋白质的特征。阐明体内不同抗原提呈途径的作用机制将为合理设计疫苗和诱导保护性CD 8 + T细胞的免疫策略提供基础。

DESCRIPTION (provided by applicant): CD8+ T cells are critical components of the anti-viral immune response to some viruses. Naive CD8+ T cells differentiate into effector cells only after recognition of peptide-MHC Class I complexes on the surface of antigen presenting cells (APC). The peptides presented can be generated from protein antigens via a number of pathways in vivo. Peptides can be produced from antigens expressed within a virus-infected APC, when presentation is termed direct-priming. Alternatively, peptides can be produced from proteins that are transferred from other cells to APC prior to presentation, a process known as cross-priming. The extent to which direct-priming or cross-priming contribute to activation of naive CD8+ T cells in vivo is not known. The overall objective of this project is to delineate the mechanisms used to generate MHC Class I-peptide complexes during priming of naive CD8+ T cells in vivo. Our underlying hypothesis is that alteration in protein expression can, and does, direct in vivo antigen presentation into direct or cross-priming pathways. To examine this issue we will use recombinant viruses to express multiple protein antigens and will analyze antigen presentation to naive and effector CD8+ T cells both in vitro and in vivo. ln Aim 1 we will determine the effects of targeting viral antigen for expression in specific tissues on the pathways of antigen presentation used in vivo. We will examine the timing and efficiency of CD8+ T cell priming to ubiquitously expressed or tissue-targeted antigen. We will also identify the APC responsible for priming via each route, and examine the properties of this APC that are necessary for effective priming. In Aim 2 we will examine differential antigen presentation as a mechanism for the reduced immunogenicity of virus genes expressed late in the virus life cycle. In addition, by using a natural example of antigen shuttled into different antigen presentation pathways in vivo we will compare the efficiency of CD8+ T cell priming via direct or cross-priming to the amount of antigen made in vivo. In Aim 3 we will determine, in vitro and in vivo, the characteristics of proteins that are preferentially transferred from virus-infected cells to APC during cross-priming. Delineation of the mechanisms governing the use of different antigen presentation pathways in vivo will provide a basis for the rational design of vaccines and immunotherapeutic strategies aimed at induction of protective CD8+ T cells.