Protection of Mice From Lethal Alphavirus Encephalitis

描述（由申请人提供）：甲病毒是全球人类致死性脑炎的重要原因。由于它们可能被用作生物恐怖主义制剂，许多也被美国公共卫生服务局指定为B类优先病原体。一种甲病毒Sindbis病毒（SV）已在小鼠模型中得到广泛研究。特别是，一种神经适应毒株（NSV）在易感宿主中诱发一种高度可复制的疾病，伴后肢瘫痪和死亡，并在7-10天内演变。所有SV毒株都以大脑和脊髓中的神经元为目标，这些细胞的命运决定了神经毒性。此外，未感染的神经元也通过旁观者机制受损，宿主免疫反应现在已涉及病毒发病机制的这一方面。我们知道中枢神经系统（CNS）的内源性巨噬细胞样细胞小胶质细胞在NSV感染后很快被激活，我们现在发现两种不相关的药物抑制这种小胶质细胞的激活过程也可以保护小鼠免受NSV诱导的后肢瘫痪和死亡，而不会对中枢神经系统病毒的复制或传播产生任何影响。为了更详细地研究这种独特的非NSV脑脊髓炎保护形式，我们提出：(1)使用仅在明显神经系统疾病发病时或发病后开始给药的治疗方案，进一步表征神经保护药物对nsv感染小鼠的有益作用，表征我们模型中已知针对小胶质细胞的其他抗炎药物的作用，并验证我们所有的保护药物对导致人类致命脑炎的其他新世界甲病毒的作用。(2)研究nsv诱导的后肢体瘫痪和死亡的药物介导保护的组织病理学相关性，并进一步表征每种药物如何影响体内中枢神经系统的小胶质细胞激活和体外小胶质细胞诱导的原代神经元损伤。(3)利用cDNA微阵列方法比较保护性药物治疗或不治疗nsv感染动物纯化组织小胶质细胞基因表达的时间模式。(4)对保护性药物治疗方案调节的cDNA微阵列分析鉴定的候选基因进行功能表征，并确定这些候选基因在体内是否参与NSV发病机制，在体外是否参与小胶质细胞诱导的神经毒性。

DESCRIPTION (provided by applicant): Alphaviruses are important causes of fatal encephalitis in humans worldwide. Many are also designated as Category B Priority Pathogens by the U.S. Public Health Service given their potential use as bioterrorism agents. One alphavirus, Sindbis virus (SV), has been extensively studied in a murine model. In particular, a neuroadapted strain (NSV) induces a highly reproducible disease in susceptible hosts with hindlimb paralysis and death that evolves over a period of 7-10 days. All strains of SV target neurons in the brain and spinal cord, and the fate of these cells determines neurovirulence. Further, non-infected neurons are also damaged via bystander mechanisms, and host immune responses have now been implicated in this aspect of viral pathogenesis. We know that microglia, the endogenous macrophage-like cell of the central nervous system (CNS), become activated soon after NSV infection, and we now show that two unrelated drugs that inhibit this microglial activation process also protect mice from NSV-induced hindlimb paralysis and death without exerting any effect on CNS viral replication or spread. In order to study this unique form of protection against NSV encephalomyelitis in greater detail, we propose: (1) To further characterize the beneficial effects of neuroprotective drugs in NSV-infected mice using treatment regimens where dosing begins only at or after the onset of overt neurologic disease, to characterize the effects of other anti-inflammatory agents known to target microglia in our model, and to verify the effects of all our protective agents against other New World alphaviruses that cause fatal encephalitis in humans, (2) To investigate histopathological correlates of drug-mediated protection from NSV-induced hindlimb paralysis and death, and to further characterize how each drug affects microglial activation in the CNS in vivo and microglial-induced injury of primary neurons iin vitro, (3) To compare temporal patterns of gene expression in purified tissue microglia from NSV-infected animals with or without protective drug treatment using cDNA microarray methodologies, and (4) To functionally characterize candidate genes identified by cDNA microarray analysis that are modulated by protective drug treatment regimens and to determine whether these candidates contribute to NSV pathogenesis in vivo and to microglial-induced neurotoxicity in vitro.