Selection of inflationary and tissue-resident T cells during MCMV infection

描述（由申请人提供）：巨细胞病毒（CMV）是一种普遍存在的疱疹病毒，可引起系统性、持续性感染。巨细胞病毒已经进化到很少在人类中引起严重疾病，因为系统的、终身的免疫监测可以控制病毒。事实上，巨细胞病毒刺激了人体循环中已知的最大的T细胞群。随着时间的推移，这些T细胞在一个称为“记忆膨胀”的过程中积累，并通过关闭病毒在潜伏期的再激活来系统地迁移以控制巨细胞病毒。由于这些原因，巨细胞病毒可以作为一种工具，用于开发针对癌症和艾滋病毒等疾病的新疫苗。然而，关于巨细胞病毒如何成功地重新激活并在免疫监视中周期性地从宿主中脱落，仍有许多未知之处。当巨细胞病毒传播给孕妇时，会对发育中的胎儿造成毁灭性的疾病。因此，预防巨细胞病毒传播的疫苗被医学研究所列为最高优先事项。了解病毒脱落部位的免疫监测将是预防传播和巨细胞病毒疾病的关键。最近的研究表明，一种称为“常驻记忆”T细胞（TRM）的T细胞群建立在体内可能面临病毒再激活的部位。事实上，TRM细胞可能有助于控制疱疹病毒的再激活。然而，目前还没有cmv特异性TRM细胞的研究。使用天然小鼠疱疹病毒，小鼠(M)CMV，我们的数据显示，许多MCMV特异性TRM细胞在唾液腺和乳腺中发育，这两个部位是MCMV已知的脱落部位。TRM细胞的个体发育尚不明确，这一缺口至关重要，因为这些T细胞处于最佳位置，可能对控制疱疹病毒再激活至关重要。此外，促进这种“第一反应者”——位于病原体入侵部位的细胞——是巨细胞病毒载体疫苗的主要优势。当前提案的目标1将表征mcmv特异性TRM细胞，确定它们是否定位于感染的上皮，以及它们的维持是否依赖于已知的参与者，即TGF-¿，CD103（¿E¿7整合素）和CD69。目的2将确定MCMV特异性TRM细胞的发育是否取决于局部病毒复制或MCMV免疫逃避的功效。MCMV在唾液腺中进行长时间的复制，并很容易在唾液腺中被重新激活，这是典型的疱疹病毒在脱落部位的特征。然而，MCMV免疫逃避被认为在唾液腺中非常有效。因此，我们将确定MCMV特异性TRM细胞是由于局部MCMV感染而发展还是不受其影响。最后，我们的初步数据表明，流通中的记忆膨胀是由对病毒抗原的竞争驱动的。成功竞争的T细胞膨胀；那些无法竞争的企业则没有。值得注意的是，我们的数据表明，mcmv特异性TRM细胞富集于不经历记忆膨胀的T细胞。因此，Aim 3将确定无法竞争MCMV抗原的T细胞是否优先在TRM池中富集，以及T细胞受体对病毒肽的亲和力是否决定了加入膨胀型或常驻型T细胞池的决定。

DESCRIPTION (provided by applicant): Cytomegalovirus (CMV) is a ubiquitous herpesvirus that establishes a systemic, persistent infection. CMV has evolved to rarely cause serious disease in humans because systemic, life-long immune surveillance keeps the virus in check. In fact, CMV stimulates the largest known T cell populations in the circulation of humans. These T cells accumulate over time in a process called "memory inflation" and migrate systemically to control CMV by shutting down viral reactivation from latency. For these reasons, CMV may serve as a tool for new vaccines against diseases such as cancer and HIV. However, much remains unknown about how CMV manages to successfully reactivate to be periodically shed from a host, in the midst of immune surveillance. CMV can cause devastating disease in a developing fetus when the virus is transmitted to a pregnant woman. Thus, a vaccine to prevent CMV transmission is rated as a highest priority by the Institute of Medicine. Understanding immune surveillance at sites of viral shedding will be key to preventing transmission and CMV disease. Recent work has shown that a T cell population called "resident memory" T cells (TRM) are established at sites in the body that may face viral reactivation. Indeed, TRM cells may help control herpesvirus reactivation. However, there have been no studies of CMV-specific TRM cells. Using the natural mouse herpesvirus, murine (M)CMV, our data show that many MCMV-specifics TRM cells developed in the salivary and mammary glands - two sites from which MCMV is known to be shed. The ontogeny of TRM cells is poorly defined, and this gap is critical because these T cells are best positioned and possibly critical for controlling herpesvirus reactivation. Moreover, the promotion of such "first responders" - cells positioned at the site of pathogen invasion - is the major advantage of CMV-vectored vaccines. Aim 1 of the current proposal will characterize MCMV-specific TRM cells, determine whether they localize to infected epithelium, and whether their maintenance depends on known players - namely TGF-¿, CD103 (¿E¿7 integrin) and CD69. Aim 2 will determine whether the development of MCMV-specific TRM cells depends on local viral replication or the efficacy of MCMV immune evasion. MCMV undergoes prolonged replication in the salivary gland and is readily reactivated there, which is typical of herpesviruses at sites of shedding. However, MCMV immune evasion is thought to be highly effective in the salivary gland. Thus, we will determine whether MCMV-specific TRM cells develop because of the local MCMV infection or in spite of it. Finally, our preliminary data show that memory inflation in circulation is driven by a competition for viral antigen. T cells that successfully compete, inflate; those that fail to compete do not. Remarkably, our data suggest that MCMV-specific TRM cells were enriched for T cells that do not undergo memory inflation. Thus, Aim 3, will determine whether T cells that fail to compete for MCMV antigen are preferentially enriched in the TRM pool and whether the affinity of the T cell receptor for viral peptide dictates the decision to join the inflationary or resident T cell pools.