Immune Regulation of Viral Recrudescence

描述(申请人提供)：中枢神经系统(CNS)是急性脑炎病毒感染的主要目标，也是潜伏/持续病毒的储存库。而当 在免疫能力强的个体中，对持续病毒的有效免疫控制反映在没有明显的神经缺陷或病理上，这种平衡是非常脆弱的。该奖项支持的研究首次证明，即使早期T细胞介导的控制和抗病毒血清抗体(Ab)的存在，鞘内抗体分泌细胞(ASC)对控制中枢神经系统病毒的持久性也是关键的。我们还通过识别关键的趋化因子受体和趋化因子来确定ACS重新进入中枢神经系统的调节。在嗜神经性冠状病毒感染期间，依靠局部ASC延长抗体的输出是一个关键的观察结果，因为它提供了一种适用于许多嗜神经性感染的持续免疫控制的有效的非溶血性机制。事实上，ASC的重要局部保护作用得到了其他实验性中枢神经系统感染的支持，特别是由Sindbis、Semliki森林和狂犬病病毒等RNA病毒支持。在与神经系统并发症和多发性硬化症(MS)脱髓鞘疾病相关的感染期间，鞘内抗体合成也被很好地记录下来。然而，对于ASC在中枢神经系统或其他专门微环境中的起源、维持和相关性几乎一无所知。总体目标是定义中枢神经系统内保护性但破坏性最小的ASC的调节，以对抗病毒在没有明显血脑屏障损害或炎症信号的情况下在中枢神经系统复制的感染。其具体目的是：1)确定CNS驻留细胞在调节ASC进入和定位中的作用；2)确定迁移性ASC与循环中的、非抗体分泌的记忆B细胞在维持CNS内ASC方面的相对贡献。原位杂交结合共聚焦显微镜将确定趋化因子、病毒抗原、ASC定位和微血管之间的空间关系。这一结果将进一步揭示星形胶质细胞在调节ASC招募中的核心作用。目的利用表型标记生发中心来源的ASC和记忆B细胞的转基因小鼠，特异性地检测病毒特异性B细胞在慢性中枢神经系统感染过程中促进ASC维持的作用。采用转移将确定中枢神经系统内ASC的初始爆发是否足以维持当地的保护能力。在病毒性或自身免疫性脑脊髓炎期间，这些参数都没有被研究过。使用转基因标记追踪ASC和Bmem的能力为分析易持续感染的非淋巴器官的体液免疫提供了一种通用的创新方法。在与有限的持续炎症相关的持续性感染期间，外周激活的B细胞而不是淋巴组织新生在维持鞘内体液反应方面的贡献将有助于理解麻疹病毒、风疹病毒、JC病毒和HIV引起的人类中枢神经系统感染时的保护性反应。

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.