Neurobiology of Varicella Zoster Virus

 描述(申请人提供)：水痘带状疱疹病毒(VZV)每年在全球数十亿儿童中引起水痘(水痘)，之后病毒在整个神经轴的神经节神经元中潜伏。几十年后，VZV特异性细胞免疫功能下降，病毒重新激活，导致带状疱疹(带状疱疹)，其特征是疼痛和皮疹仅限于1-3个皮肤体。带状疱疹每年影响约100万美国人，通常并发慢性神经根性疼痛(带状疱疹后神经痛，PHN)和其他严重的神经系统(小脑炎、脊髓炎和血管病变)和眼部疾病，这些疾病共同导致 瘫痪、失明和死亡。到2030年，22%的美国人(6500万人)的年龄将达到65岁，85岁的人口将增加两倍，达到800万。带状疱疹的发病率和严重程度从 随着年龄的增长，VZV特异性免疫力自然下降，出现在器官移植接受者以及癌症和艾滋病患者中的更严重的宿主免疫缺陷。带状疱疹疫苗可以在长达3年的时间里将带状疱疹的发病率降低50%，但即使60岁的每个人都接种疫苗，每年仍预计会有50万带状疱疹病例和20万例PHN病例。因此，随着老年人口的增加，带状疱疹的发病率及其随之而来的神经和眼部并发症也随之增加。在1983年首次证明VZV在人类神经节中潜伏后，我们随后对来自&gt；900随机解剖对象的&gt；7,000个人类神经节进行了分析，揭示了整个病毒基因组在神经元中的存在，很可能保持为具有可变VZV DNA丰度的组蛋白包裹的Episome，VZV转录仅限于ORF63，以及VZV基因表达的表观遗传调节。为了更准确地确定病毒基因表达的范围和潜伏的VZV基因组上的表观遗传标记，我们检查了VZV感染的分化神经元，这些神经元在培养长达3周时仍然活着，没有细胞病变；用干扰素治疗这些神经元显著降低了病毒基因的表达。因此，我们假设，限制VZV基因表达的神经元将产生一个模型系统，在潜伏感染的人类神经节细胞中概括VZV转录。为了验证我们的假设，我们将：用抗病毒药物和由天然免疫系统和获得性免疫系统的细胞产生的分子在体外治疗VZV非裂解感染神经元，并通过RT-PCR检测VZV基因的表达(目标1)；确定VZV DNA的物理状态、VZV基因的表达以及经阿昔洛韦和多种细胞因子治疗后VZV基因组上存在的表观遗传标记(目标2)。开发VZV潜伏期的体外模型将允许进行通常需要获取数千个人类神经节的研究。深入了解VZV如何长期驻留在潜伏感染的人类神经细胞中，是制定策略以防止导致病毒重新激活的级联事件的先决条件，病毒重新激活是导致严重神经系统疾病和失明的原因，特别是在迅速增长的老年和免疫功能受损人群中。

 DESCRIPTION (provided by applicant): Varicella zoster virus (VZV) causes varicella (chickenpox) in billions of children worldwide annually, after which virus becomes latent in ganglionic neurons along the entire neuraxis. Decades later, VZV-specific cell-mediated immunity declines and virus reactivates, resulting in zoster (shingles), characterized by pain and rash restricted to 1-3 dermatomes. Zoster affects ~1 million Americans yearly and is often complicated by chronic radicular pain (postherpetic neuralgia, PHN) and other serious neurological (cerebellitis, myelitis and vasculopathy) and ocular disorders that collectively cause paralysis, blindness and death. By 2030, 22% of Americans (65 million people) will be >age 65, and the >85 population will triple to >8 million. The incidence and severity of zoster range from a natural decline in VZV-specific immunity with advancing age to more serious host immune deficits seen in organ transplant recipients and in patients with cancer and AIDS. Zoster vaccine reduces the incidence of zoster by 50% for up to 3 years, yet even immunization of everyone >age 60 still predicts 500,000 cases of zoster and 200,000 cases of PHN annually. Thus, as the elderly population increases, so does the incidence of zoster and its attendant neurological and ocular complications. After first proving in 1983 that VZV is latent in human ganglia, our subsequent analyses of >7,000 human ganglia from >900 randomly autopsied subjects revealed the presence of the entire virus genome in neurons, most likely maintained as a histone-coated episome with variable VZV DNA abundance, VZV transcription restricted to ORF63, and epigenetic regulation of VZV gene expression. To more precisely define the extent of viral gene expression and epigenetic markers on the latent VZV genome, we examined VZV-infected differentiated neurons, which remained viable in culture up to 3 weeks without a cytopathic effect; treatment of these neurons with interferon- ¿ significantly reduced viral gene expression. Thus, we hypothesize that neurons treated to limit VZV gene expression will yield a model system that recapitulates VZV transcription in latently infected human ganglionic neurons. To test our hypothesis, we will: treat VZV non-lytically infected neurons in vitro with antiviral agents and molecules produced by cells of the innate and adaptive immune systems and examine VZV gene expression by RT-PCR (Aim 1); determine the physical state of VZV DNA, VZV gene expression and epigenetic markers present on VZV genomes within non-lytically infected neurons after treatment with acyclovir and multiple cytokines (Aim 2). Developing a model of VZV latency in vitro will allow studies that would normally require acquisition of thousands of human ganglia. An in-depth understanding of how VZV resides long-term in latently infected human nerve cells is prerequisite to developing strategies that prevent the cascade of events leading to virus reactivation, a cause of serious neurologic disease and blindness, particularly in the rapidly increasing elderly and immunocompromised populations.