Cytotoxic T Cell Responses to Virus Infection

描述（由申请人提供）：CD 8+记忆T细胞是成功接种疫苗的基石之一，并且关于其产生，即决定初始CD 8 + T细胞活化、扩增和收缩的途径以及影响CD 8+记忆T细胞亚群建立的因素，已经有很多了解。相比之下，我们对CD 8+记忆T细胞回忆反应知之甚少，而疫苗的功效依赖于此。记忆细胞在体内处理单个病毒感染的细胞，并且为了有效地这样做，它们必须对二次感染（即，开始它们的回忆反应）通过将它们的效应器功能强加于受感染者 在许多病毒感染中，这意味着记忆T细胞必须在感染后数小时内发挥作用，才能发挥最大的保护作用。因此，我的实验室最近开始研究极早期（d24小时p.i.）CD 8+记忆T细胞的回忆反应;并且，尽可能地，我们在体内测量反应。未公开的数据（本文提供）显示：（i）CD 8+记忆T细胞在3-6小时内（早在单轮病毒复制完成之前）在体内启动对病毒感染的效应子应答;和（ii）非常令人惊讶的是，体内细胞因子合成（IFN、TNF和IL-2）在此后不久（到感染后24小时）基本上终止。这种效应器功能的终止发生， 免疫刺激性病毒抗原的存在，表明对感染有应答的CD 8+记忆T细胞对效应子功能有主动下调。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，将在四个具体目标中进行探索。1.研究CD 8+记忆T细胞早期回忆反应的体内调控。我们的观察关于CD 8+记忆T细胞的效应功能的快速开/关表达将扩大。2.识别和操纵支持CD 8+记忆T细胞早期回忆反应的分子途径。调节效应子功能的起始和终止的分子机制将使用几种方法来鉴定。3.评估树突状细胞在调节这些非常早期的记忆T细胞反应中的作用。大多数DC / T细胞相互作用的研究都（可以理解）集中在初始T细胞的引发上。在这里，我们将评估DC在CD 8+记忆T细胞的快速体内应答中的作用。4.为了产生和测试一个小鼠系，这将使我们能够第一次评估各种蛋白质在调节CD 8+记忆T细胞回忆反应中的重要性。我们将产生一个转基因小鼠系，允许研究者在他/她选择的时间从CD 8 + T细胞中删除一个基因。一只受感染的小鼠会产生完全正常的初级T细胞反应，并建立一个正常的记忆细胞库;只有这样，我们才能删除感兴趣的基因。

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 Unpublished data (presented herein) show that: (i) CD8+ memory T cells initiate effector responses to virus infection in vivo within 3-6 hours (long before a single round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.