Mechanisms and optimization of epitope presentation by HIV-infectable cell subset

项目概要/摘要 HIV特异性细胞毒性T淋巴细胞（CTL）在急性感染或慢性感染中抑制HIV病毒血症中起关键作用。 自发控制的情况下，使它们成为疫苗战略的有吸引力的候选人。然而 尽管产生了CTL应答，但迄今为止开发的疫苗未能保护免受HIV感染。 事实上，针对病毒某些区域的CTL应答可能在控制HIV方面更有效。 与其他特异性CTL相比，疫苗的复制表明疫苗应引起选择性CTL应答 与保护有关。HIV感染细胞对同源表位的有效呈递是HIV感染的关键。 保护性CTL应答的条件。然而，对细胞内的 调节CD 8 T细胞识别的HIV表位呈递的机制。大多数关于艾滋病毒的研究- 特异性CTL功能利用合成肽形式的同源表位，从而绕过所有细胞内表位 导致表位呈递的蛋白质降解步骤。HIV感染几种表达CD 4的 这些细胞亚群（CD 4 T细胞、单核细胞/巨噬细胞和树突细胞）将呈递HIV表位。是否 这些亚群以相同的动力学呈现相似的表位是未知的。表位呈递的变化 亚群间的差异可能影响CTL的抗病毒效果。相反，确定艾滋病毒的有效领域， 加工成所有亚群中的表位对于鉴定保护性CTL是最重要的 免疫反应和免疫原的选择。基于新的表位加工测定，我们显示了优先的 处理一些HIV表位，这一特性依赖于我们用来改变不相关抗原表位产生的基序。 表位我们还鉴定了一种参与表位加工效率的新因子，即高度可变的 最佳HIV表位的细胞内稳定性，也由特定基序驱动。最后，我们发现CD 4 T细胞 具有比单核细胞低的加工活性，这影响降解的动力学和抗原性 HIV蛋白的产物。这些数据表明，表位的产生是由一些规则控制的， 用来设计定制的免疫原具体而言，我们建议：1）确定CTL应答是否 与HIV病毒血症的自发控制相关，它有效地识别并杀死所有HIV感染细胞亚群。 利用大量的控制者和进展者，我们将评估CD 8 T的功能。 受各种HIV感染亚群刺激的细胞。2)鉴别不同抗原中通常产生的肽 导致自发性受控病毒血症的可感染亚群的处理途径。使用纳米颗粒 为了靶向细胞亚群内的HIV蛋白，我们将鉴定所有亚群产生的抗原肽。3)设计 以及导致保护性HIV表位的选择性呈递的测试序列特征。这项建议 依赖于跨学科的合作方法，涉及计算科学，生物工程工具和 针对原代细胞设计的表位加工和CTL功能的生物化学和免疫学测定。

Project summary/abstract HIV-specific cytotoxic T-lymphocytes (CTL) play a critical role in containing HIV viremia in acute infection or in situation of spontaneous control, rendering them attractive candidates for vaccine strategies. However vaccines developed so far have failed to protect against HIV infection, this despite generating CTL responses. The fact that CTL responses against certain areas of the virus may be more effective at controlling HIV replication than CTL with other specificities suggests that vaccine should elicit selected CTL responses associated with protection. Effective presentation of the cognate epitopes by HIV-infected cells is a crucial condition for protective CTL responses. However, there is still surprisingly little understanding of intracellular mechanisms governing the presentation of HIV epitopes recognized by CD8 T cells. Most studies on HIV- specific CTL functions utilize cognate epitopes in the form of synthetic peptides, thus bypassing all intracellular steps of protein degradation leading to the presentation of epitopes. HIV infects several CD4-expressing subsets (CD4 T cells, monocyte/macrophages and dendritic cells) that will present HIV epitopes. Whether these subsets present similar epitopes with identical kinetics is unknown. Variations in epitope presentation between subsets may affect the antiviral efficacy of CTL. Conversely identifying areas of HIV that are efficiently processed into epitopes in all subsets is of highest importance for the identification of protective CTL responses and selection of immunogens. Building on novel epitope processing assays, we showed preferential processing of some HIV epitopes, a property that relies on motifs we used to alter the production of irrelevant epitopes. We also identified a novel factor involved in epitope processing efficiency, namely the highly variable intracellular stability of optimal HIV epitopes, also driven by specific motifs. Finally we show that CD4 T cells have lower processing activities than monocytes, which affects the kinetics and antigenicity of degradation products from HIV proteins. These data suggest that epitope production is controlled by rules that could be exploited to design customized immunogens. Specifically we propose to: 1) Determine whether CTL responses associated with spontaneous control of HIV viremia efficiently recognize and kill all HIV-infectable cell subsets. Taking advantage of a large cohort of controllers and progressors, we will assess the functionality of CD8 T cells stimulated by various HIV-infected subsets. 2) Identify peptides commonly produced in distinct antigen processing pathways of infectable subsets contributing to spontaneous controlled viremia. Using nanoparticles to target HIV proteins inside cell subsets, we will identify antigenic peptides produced by all subsets. 3) Design and test sequence signatures leading to the selective presentation of protective HIV epitopes. This proposal relies on a cross-disciplinary collaborative approach involving computational science, bioengineered tools and biochemical and immunological assays of epitope processing and CTL functions designed for primary cells.