Cytotoxic T Cell Responses to Virus Infection

描述(申请人提供)：CD8+记忆T细胞是成功接种疫苗的基石之一，人们对其产生有很多了解，即决定原始CD8+T细胞激活、扩张和收缩的途径，以及影响CD8+记忆T细胞亚群建立的因素。相比之下，我们对CD8+记忆T细胞召回反应知之甚少，疫苗的有效性依赖于CD8+记忆T细胞召回反应。记忆细胞在体内处理单个感染病毒的细胞，为了有效地做到这一点，它们必须对二次感染做出反应(即开始它们的回忆反应)，将它们的效应器功能强加给受感染的人 对于许多病毒感染来说，这意味着--如果要发挥最大的保护作用--记忆T细胞必须在感染后几小时内发挥作用。因此，我的实验室最近已经开始调查非常早的(D24小时P.I.)CD8+记忆T细胞的回忆反应；并尽可能测量体内的反应。未发表的数据显示：(I)CD8+记忆T细胞在体内3-6小时内启动对病毒感染的效应反应(远在单轮病毒复制完成之前)；以及(Ii)非常令人惊讶的是，体内细胞因子的合成(干扰素、肿瘤坏死因子和白介素2)在此后不久(到24小时P.I.)基本终止。这种效应器功能的终止 免疫刺激病毒抗原的存在，表明对感染有反应的CD8+记忆T细胞主动下调效应器功能。这些事件发生在记忆T细胞增殖之前。这些早期的回忆反应，以及控制它们的分子机制，将从四个具体的目标进行探索。1.探讨CD8+记忆T细胞早期回忆反应的体内调节。我们关于CD8+记忆T细胞快速开/关表达效应功能的观察将被扩大。2.鉴定和调控支持CD8+记忆T细胞早期回忆反应的分子途径(S)。调控效应器功能的启动和终止的分子机制(S)将使用几种方法来确定。3.评价树突状细胞在调节这些早期记忆T细胞反应中的作用。大多数关于DC/T细胞相互作用的研究(可以理解)都集中在NAVE T细胞的启动上。在这里，我们将评估树突状细胞在CD8+记忆T细胞体内快速反应中的作用。4.建立和测试一种小鼠品系，使我们能够第一次评估各种蛋白质在调节CD8+记忆T细胞回忆反应中的重要性。我们将产生一种转基因小鼠，它将允许研究人员在他/她选择的时间从CD8+T细胞中删除一个基因。受感染的小鼠会建立一个完全正常的初级T细胞反应，并建立一个正常的记忆细胞库；只有到那时，我们才会删除目标基因。

DESCRIPTION (provided by applicant): CD8+ memory T cells are one of the cornerstones of successful vaccination, and much is known about their generation, i.e. the pathways that determine na¿ve CD8+ T cell activation, expansion & contraction, and the factors that affect the establishment of CD8+ memory T cell subsets. In contrast, we know relatively little about CD8+ memory T cell recall responses, upon which vaccine efficacy relies. Memory cells deal with individual virus-infected cells in vivo and, to do so effectively, they must respond to secondary infection (i.e., begin their recall response) by imposing their effector functions upon an infected cell before virus progeny has been released; for many virus infections, this means that - if they are to be maximally protective - memory T cells must act within hours of infection. Hence, my lab recently has begun to investigate the very early (d24 hours p.i.) recall responses of CD8+ memory T cells; and, so far as is possible, we measure the responses in vivo. Unpublished data (presented herein) show that: (i) CD8+ memory T cells initiate effector responses to virus infection in vivo within 3-6 hours (long before a single round of virus replication has been completed); and (ii) very surprisingly, in vivo cytokine synthesis (IFN¿, TNF & IL-2) is largely terminated soon thereafter (by 24 hours p.i.). This termination of effector function occurs despite the presence of immunostimulatory viral antigen, suggesting that there is active down-regulation of effector function by CD8+ memory T cells that have responded to infection. These events occur before the memory T cells have multiplied. These early recall responses, and the molecular mechanisms that control them, will be explored in four Specific Aims. 1. To investigate the in vivo regulation of CD8+ memory T cell early recall responses. Our observations regarding the rapid on/off expression of effector functions by CD8+ memory T cells will be expanded. 2. To identify and manipulate the molecular pathway(s) underpinning the early recall response of CD8+ memory T cells. The molecular mechanisms regulating the initiation, and the termination, of effector function(s) will be identified using several approaches. 3. To evaluate the role of dendritic cells in regulating these very early memory T cell responses. The majority of studies of DC / T cell interactions have (understandably) focused on priming of na¿ve T cells. Here, we shall evaluate the role of DCs in the rapid in vivo responses of CD8+ memory T cells. 4. To generate and test a mouse line that would allow us, for the first time, to evaluate the importance of various proteins in regulating the recall responses of CD8+ memory T cells. We shall generate a transgenic mouse line which will allow the investigator to deletion a gene from CD8+ T cells at the time of his/her choosing. An infected mouse would mount a completely normal primary T cell response, and would establish a normal memory cell pool; only then would we delete the gene of interest.