Fate of neurons following immune-mediated viral clearance

描述（由申请人提供）：尽管有大量的病毒可以感染人脑，并且越来越多的人怀疑一些嗜神经病原体在慢性神经退行性疾病中起直接或辅助作用，但对感染后神经元的命运知之甚少。据推测，神经元可以在感染和免疫事件中存活下来，导致治愈的细胞在功能上与感染前的声型无法区分，尽管这还没有经过实验测试。虽然有大量证据表明，免疫能力强的小鼠在中枢神经系统内产生保护性反应，解决病毒感染，导致很少的明显炎症损伤和明显的无损伤生存，但两个关键问题仍未得到解答，这是该建议的基础。第一：神经元真的能在抗病毒免疫反应中存活吗？第二：如果神经元可以被病毒治愈，它们的功能是否正常？这些问题将通过一个具有良好特征的小鼠系统（基因Cre报告小鼠）来解决，以跟踪病毒感染神经元的后果。被两种嗜神经RNA病毒（麻疹病毒或狂犬病病毒）中的一种感染的神经元将被荧光信号永久地从红色变为绿色所“标记”。在整个感染过程中，无论是否存在有效的免疫反应，都可以对这些神经元进行监测。此外，标记的（绿色）神经元可以通过激光捕获显微解剖分离，用于随后的基因和蛋白质表达分析。识别、分离和表征活跃感染神经元或先前被宿主免疫反应治愈的感染神经元的能力将允许更精确的研究来定义包括年龄、神经元亚型、病毒类型和免疫效应器在内的变量如何影响CNS神经元的存活和功能。最后，鉴于该系统可以广泛应用于几乎任何CNS病毒感染的小鼠模型，我们相信在神经病毒学和神经发病机制领域有可能取得重大进展。

DESCRIPTION (provided by applicant): Despite the large number of viruses that can infect the human brain, and the growing suspicion that some neurotropic pathogens play a direct or contributory role in chronic neurodegenerative diseases, little is known about the fate of neurons following infection. It has been surmised that neurons can survive an infection and immunity event, resulting in cured cells that are functionally indistinguishable from the pre-infection phonotype, though this has not been experimentally tested. While there is abundant evidence that immunocompetent mice mount a protective response within the CNS that resolves a viral infection, leading to little overt inflammatory damage and apparent impairment-free survival, two critical questions remain unanswered, which are the basis for this proposal. First: do neurons, in fact, survive the anti- viral immune response? Second: If neurons can be cured of a virus, are they functionally competent? These questions will be addressed using a well-characterized mouse system (congenic Cre reporter mice) to follow the consequences of viral infection of neurons over time. Neurons that have been infected with one of two neurotropic RNA viruses (measles or rabies) will be "marked" by a permanent change in fluorescence signal from red to green. These neurons can then be monitored throughout the infection course in the presence or absence of a competent immune response. Moreover, marked (green) neurons can be isolated by laser capture microdissection for subsequent gene and protein expression analyses. The ability to identify, isolate and characterize actively infected neurons or previously infected neurons that have been cured by the host immune response will allow for more precise studies to define how variables including age, neuronal subtype, virus type, and immune effectors impact on CNS neuron survival and function. Finally, given that this system can be broadly applied to virtually any mouse model of CNS viral infection, we believe there is the potential to enable major advances in the fields of neurovirology and neuropathogenesis. PUBLIC HEALTH RELEVANCE: This proposal will explore the utility of a novel mouse model to explore neuronal survival and function following virus infection. In this model, neurons that have been infected by Cre- recombinase expressing viruses undergo a permanent, readily detectable color change from red to green, serving as a marker of previous infection. Using two well-characterized neurotropic viruses (measles and rabies), neuronal survival and function will be assessed during active infection and at various timepoints post-clearance. The information obtained from these studies will have direct translational links that will guide therapeutic strategies to prevent or resolve neurotropic infections in humans, aid viral vector-based gene therapy strategies, and elucidate what role, if any, viruses play in neurodegenerative diseases of unknown etiology.