Alphavirus-manganese interactions and dopaminergic neurodegeneration

描述（由申请人提供）：病毒感染被认为是神经退行性疾病，包括帕金森病（PD）的可能危险因素。嗜神经型甲病毒感染可产生许多与PD相同的长期退行性影响，包括蛋白质聚集、氧化应激水平升高、自噬/自噬缺陷、神经炎症和神经元死亡。因此，嗜神经病毒可能代表了一种更好的动物模型，用于研究PD中基因与环境的相互作用，它比基于药物的病变模型或遗传模型更能概括人类疾病的特征，这些模型通常在实质黑质中缺乏明显的表型。有证据表明，病毒感染可能与其他已知的风险因素协同作用，如衰老、遗传因素和/或先前暴露于环境神经毒素，以促进神经退行性变。在可能与嗜神经病毒有明显基因x环境相互作用的神经毒素中，锰（Mn）引起了人们的兴趣，因为在生命早期过量接触锰会对神经功能产生持久影响，也会增强甲病毒的神经毒性。在这里，我们提出了一种新的方法来检测基因x环境相互作用在帕金森病使用嗜神经α病毒表达系统（AES）。在方便的鼻内接种后，100%的动物被感染，并且使用表达荧光素酶的病毒和全身生物发光成像可以无创地原位监测感染的进展。神经侵入通过嗅觉感觉神经元发生，感染沿神经元轴扩散，模仿PD的brake分期系统。病毒感染的严重程度和持续时间可以严格控制，我们使用无偏体视学的初步数据表明，AES感染导致实质黑质部致密（SNpc）中多巴胺能神经元的显著丧失。本研究的中心假设是，表达荧光素酶的甲病毒在鼻内感染会通过嗅觉和皮层下结构导致神经侵入，导致黑质中多巴胺能神经元的进行性丧失，这与胶质细胞的炎症激活有关。此外，我们假设在幼年发育期间预先暴露于锰会增加病毒介导的多巴胺能神经元损失的易感性，部分是通过增加神经炎症反应。该假设将在2年的项目期间进行两个特定目标的测试，具体目标如下：特定目标1 -确定最佳病毒滴度和

DESCRIPTION (provided by applicant): Viral infection is implicated as a possible risk-factor for neurodegenerative diseases, including Parkinson's disease (PD). Infection with neurotropic alphaviruses can produce many of the same long-term degenerative effects seen in PD, including protein aggregation, increased levels of oxidative stress, autophagy/mitophagy defects, neuroinflammation, and neuronal death. Neurotropic viruses may therefore represent a better animal model for studying gene x environment interactions in PD that recapitulate more features of the human disease than drug-based lesioning models or genetic models that often lack a pronounced phenotype in the substantial nigra. Evidence suggests that viral infection may act in synergy with other recognized risk-factors, such as aging, genetic factors, and/or previous exposures to environmental neurotoxins to promote neurodegeneration. Among neurotoxins that could have a pronounced gene x environment interaction with neurotropic viruses, Manganese (Mn) is of interest because excessive exposure early in life can have lasting effects on neurological function and can also enhance the neurovirulence of alphaviruses. Here, we propose a novel method for testing gene x environment interactions in Parkinsonism using a neurotropic alphavirus expression system (AES). Following convenient intranasal inoculation, 100% of animals become infected and the progression of infection can be non-invasively monitored in situ using luciferase-expressing viruses and whole body bioluminescence imaging. Neuroinvasion occurs through olfactory sensory neurons and the infection spreads along the neuronal axis in a pattern that mimics the Braak-staging system of PD. The severity and persistence of viral infection can be tightly controlled and our preliminary data using unbiased stereology indicate that AES infection results in significant loss of dopaminergic neurons in the substantial nigra pars compacta (SNpc). It is the Central Hypothesis of this proposal that intranasal infection with luciferase- expressing alphavirus will result in neuroinvasion through olfactory and subcortical structures resulting in progressive loss of dopaminergic neurons in the substantia nigra that is associated with inflammatory activation of glial cells. Moreover, we postulate that pre-exposure to Mn during juvenile development will enhance susceptibility to viral-mediated loss of dopaminergic neurons, in part through an increased neuroinflammatory response. This hypothesis will be tested in two Specific Aims during the 2-year project period as follows: Specific Aim 1 - Determine the optimal viral titer and phenotype for inducing persistent infection and neurodegeneration in the basal ganglia following intranasal installation of luciferase-expressing Western Equine Encephalitis Virus (WEEV); Specific Aim 2 - Characterize the disease phenotype resulting from exposure to Mn pre- and post-viral infection. We expect that these studies will demonstrate that the proposed AES-based model is a powerful method for inducing parkinsonism in mice, as well as for transgene delivery into the CNS, that can be used to identify novel gene x environment interactions relevant to PD. Additionally, we expect that exposure to Mn during juvenile development will exacerbate neurodegeneration following adult infection with WEEV. The results of these studies will increase our understanding of the environmental links to neurodegenerative disease and will provide a powerful new animal model for studying virus/toxin interactions in the CNS.