CD8 T Cell Response to Murine Cytomegalovirus

描述(申请人提供)：巨细胞病毒(CMV)感染的特征是巨大的效应/记忆T细胞反应，并在一生中保持在高水平--一种被称为记忆膨胀的现象。我们已经报道过，“膨胀性记忆”细胞实际上是从感染早期产生的真实记忆细胞不断分化而来的短期效应细胞。真正的记忆细胞不容易从受感染的宿主的脾转移到受感染的接受者身上，我们认为它们驻留在基质利基中。我们还表明，一个单周期的CMV在第一次进入人体时不能传播到它感染的细胞之外，导致惊人的强大的记忆膨胀。这两个发现定义了我们在这个项目中试图解开的悖论：少数受感染的细胞如何呈现抗原，以保持免疫系统的持续激活，而不会受到免疫根除的影响？我们首先询问有关病毒存在的信息是通过病毒抗原的直接递呈还是交叉递呈传递给T细胞。这将通过产生一种表达KB的病毒来实现，以便将抗原呈递给直接感染的细胞。 接下来，我们将使用器官消化、细胞分类和生物检测的迭代过程来识别携带病毒基因组的细胞和向T细胞呈递抗原的细胞。作为另一种方法，我们将产生病毒，可用于感染cre小鼠，以限制特定组织或细胞类型的抗原表达。最后，我们将描述潜伏感染的 在与记忆CD8和CD4T细胞共同过继转移时，这些细胞的免疫学表型、病毒基因表达以及它们是否足以驱动记忆膨胀。了解推动内存膨胀的病毒式程序将使我们能够智能地 将CMV载体改造为疫苗，以产生有效的免疫反应。这也将帮助我们了解CMV在某些慢性疾病中的作用，以及它与免疫衰老的可能联系。

DESCRIPTION (provided by applicant): Cytomegalovirus (CMV) infection is characterized by enormous effector/memory T cell responses that are maintained at high levels for life- a phenomenon known as memory inflation. We have reported that "inflationary memory" cells are in fact short lived effector cells continuously differentiating from true memory cells generated early during infection. The true memory cells are not readily transferred from the spleen of an infected host to an infected recipient, and we suggest that they reside in a stromal niche. We have also shown that a single cycle CMV which is unable to spread beyond the cells it infects upon first entering the body drives surprisingly robust memory inflation. These two findings define the paradox that we seek to unravel in this project: how can a tiny number of infected cells present antigen to keep the immune system constantly activated without being subject to immune eradication? We first ask whether the information about viral presence is transmitted to T cells through direct or cross presentation of viral antigen. This will be accomplished by generating a virus expressing Kb in order to limit antigen presentation to directly infected cells. We will next use an iterative process of organ digestion, cell sorting and bioassays to identify the cells that carry the viral genome and the cells that present antigen to T cells. As an alternative approach, we will generate virus which can be used to infect cre mice to limit antigen expression to particular tissues or cell types. Finally, we will characterize the latently infected cells with respect to their immunological phenotype, their viral gene expression, and their sufficiency for driving memory inflation upon co-adoptive transfer with memory CD8 and CD4 T cells. Understanding the viral program that drives memory inflation will enable us to intelligently engineer CMV-vectors as vaccines to generate potent immune responses. It will also help us to understand CMV's role in certain chronic diseases, and its putative association with immunosenescence.