Immune Regulation of Viral Recrudescence

描述（由申请方提供）：中枢神经系统（CNS）是急性脑炎病毒感染的主要靶点，也是潜伏/持续病毒的储存库。而 在免疫活性个体中持续存在的病毒的有效免疫控制反映为没有明显的神经缺陷或病理，这种平衡是非常脆弱的。该奖项支持的研究首次证明鞘内抗体分泌细胞（ASC）对控制CNS病毒持续性至关重要，即使早期T细胞介导的控制和抗病毒血清抗体（Ab）的存在。我们还通过鉴定关键的趋化因子受体和趋化因子来确定ACS向CNS募集的调节。嗜神经性冠状病毒感染期间对局部ASC的长期Ab输出的依赖是一个关键的观察结果，因为它提供了适用于许多嗜神经性感染的持续免疫控制的有效非溶解机制。事实上，ASC的重要局部保护作用得到了其他实验性CNS感染的支持，特别是RNA病毒，如辛德比斯病毒、塞姆利基森林病毒和狂犬病病毒。在与神经系统并发症和脱髓鞘疾病多发性硬化症（MS）相关的感染期间，鞘内Ab合成也有充分的记录。然而，几乎没有什么是已知的起源，维护和相关的ASC在中枢神经系统或其他专门的微环境。总体目标是确定CNS内保护性但破坏性最小的ASC的调节，以对抗在没有明显血脑屏障损伤或炎症信号的情况下病毒在CNS中复制的感染。具体目的是：1）确定CNS驻留细胞在介导ASC进入和定位CNS中的作用;和2）确定迁移性ASC与循环的非Ab分泌记忆B细胞在维持CNS内ASC中的相对贡献。原位杂交结合共聚焦显微镜在目的1中将确定趋化因子，病毒抗原，ASC定位和微血管之间的空间关系。结果将进一步揭示星形胶质细胞在调节ASC募集中的核心作用。目的2使用转基因小鼠，在其中，来自生发中心的ASC和记忆B细胞被表型标记，以特异性地测试病毒特异性B细胞在慢性CNS感染期间促成ASC维持中的作用。连续转移将确定CNS中ASC的初始爆发是否足以维持局部保护能力。在病毒性或自身免疫性脑脊髓炎期间，这些参数均未进行过研究。使用转基因标记物追踪ASC和BCLs的能力提供了一种多功能的创新方法来剖析易持续感染的非淋巴器官中的体液免疫。外周活化的B细胞而不是淋巴组织新生在持续性感染期间维持鞘内体液应答的贡献与有限的持续性炎症相关，这将有利于理解麻疹病毒、风疹病毒、JC病毒和HIV引起的人类CNS感染期间的保护性应答。

DESCRIPTION (provided by applicant): The central nervous system (CNS) is a major target for acute encephalitic viral infections, as well as a reservoir of latent/persisting viruses. While effective immune control of persisting viruses in immunocompetent individuals is reflected by the absence of overt neurological deficits or pathology, this balance is highly tenuous. Studies supported by this award were the first to demonstrate that intrathecal antibody secreting cells (ASC) were critical to control CNS viral persistence even despite early T cell mediated control and presence of anti-viral serum antibody (Ab). We have also defined the regulation of ACS recruitment into the CNS by identifying the crucial chemokine receptor and chemokine. The reliance on local ASC for prolonged Ab output during neurotropic coronavirus infection is a critical observation, as it provides a potent non lytic mechanism of sustained immune control applicable to numerous neurotropic infections. Indeed, a vital local protective role of ASC is supported by other experimental CNS infections, particularly by RNA viruses such as Sindbis, Semliki Forest, and Rabies viruses. Intrathecal Ab synthesis is also well documented in humans during infections associated with neurological complications and the demyelinating disease multiple sclerosis (MS). However, virtually nothing is known about the origin, maintenance, and relevance of ASC in the CNS or other specialized microenvironments. The overall goal is to define the regulation of protective, yet minimally destructive ASC within the CNS, to combat infections where virus replicates in the CNS in the absence of overt blood brain barrier damage or inflammatory signals. The Specific Aims are to 1) determine the role of CNS resident cells in mediating ASC entry and localization within the CNS; and 2) determine the relative contribution of migratory ASC versus circulating, non Ab secreting memory B cells in maintaining ASC within the CNS. In situ hybridization combined with confocal microscopy in Aim 1 will determine the spatial relationship between chemokines, viral antigen, ASC localization and the microvasculature. The results will further reveal a central role of astrocytes in regulating ASC recruitment. Aim 2 uses transgenic mice in which germinal center derived ASC and memory B cells are phenotypically marked, to specifically test the role of virus specific B cells in contributing to ASC maintenance during chronic CNS infection. Adoptive transfers will define whether the initial burst of ASC in the CNS is sufficient to sustain local protective capacity. Non of these parameters have been studied during viral or autoimmune encephalomyelitis. The ability to trace ASC and Bmem using transgenic markers provides a versatile innovative approach to dissect humoral immunity in a non-lymphoid organ prone to persisting infection. The contribution of peripherally activated B cells rather than lymphoid tissue neogenesis, in sustaining intrathecal humoral responses during persistent infections associated with limited ongoing inflammation will be beneficial for understanding protective responses during human CNS infections caused by measles virus, rubella virus, JC virus, and HIV.