Protection of Mice From Lethal Alphavirus Encephalitis

描述(申请人提供)：甲型病毒是全球人类致命性脑炎的重要原因。许多还被美国公共卫生服务指定为B类优先病原体，因为它们可能被用作生物恐怖主义制剂。一种甲型病毒，辛德比斯病毒(SV)，已经在小鼠模型中进行了广泛的研究。特别是，神经适应株(NSV)在易感宿主中诱导一种高度重复性的疾病，后肢瘫痪和死亡，在7-10天内演变。所有的SV菌株都以大脑和脊髓中的神经元为靶标，这些细胞的命运决定了神经毒力。此外，未感染的神经元也通过旁观者机制受到损害，宿主免疫反应现在已被牵涉到病毒致病的这一方面。我们知道，小胶质细胞是中枢神经系统(CNS)的内源性巨噬细胞样细胞，在感染NSV后不久就会激活，我们现在证明，两种抑制这种小胶质细胞激活过程的无关药物也可以保护小鼠免受NSV诱导的后肢瘫痪和死亡，而不会对CNS病毒的复制或传播产生任何影响。为了更详细地研究这种针对NSV脑脊髓炎的独特保护形式，我们建议：(1)使用仅在显性神经疾病发生时或之后开始给药的治疗方案，进一步表征NSV感染小鼠神经保护药物的有益效果，在我们的模型中表征已知的以小胶质细胞为靶点的其他抗炎剂的效果，并验证我们所有保护剂对导致人类致命脑炎的其他新世界甲型病毒的效果，(2)研究药物介导的对NSV诱导的后肢瘫痪和死亡的保护的组织病理学相关性，为了进一步确定每种药物在体内如何影响中枢神经系统小胶质细胞的激活和小胶质细胞诱导的原代神经元损伤，(3)使用基因芯片方法比较NSV感染动物在保护性药物治疗前后的纯化组织小胶质细胞基因表达的时间模式，以及(4)从功能上表征由保护性药物治疗方案调控的cDNA微阵列分析确定的候选基因，并确定这些候选基因是否与NSV体内致病机制和体外小胶质细胞诱导的神经毒性有关。

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.