A Development-Specific Mechanism of Pathogenesis in HSV Encephalitis

HSV 脑炎发病机制的发育特异性

• 批准号: 9102730
• 负责人: Douglas Robert Wilcox
• 金额: $ 4.86万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-06-01 至 2018-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9102730
• 关键词: Accounting; Address; Adult; Animals; Apoptosis; Apoptotic; Attenuated; Autophagocytosis; Binding; Biochemical; Biological Assay; Birth; Brain; Cell Communication; Cell Death; Cells; Central Nervous System Diseases; Central Nervous System Infections; Congenital herpes simplex; Data; Development; Disease; Encephalitis; Environment; Future; Gene Deletion; Genes; Herpesvirus 1; Human Herpesvirus 2; Hypoxia; Image; Immune response; Immunofluorescence Immunologic; In Vitro; Incidence; Infection; Injury; Interferon Type I; Knock-out; Knockout Mice; Knowledge; Methods; Mitotic; Modeling; Morbidity - disease rate; Mucous Membrane; Mus; Natural Immunity; Neonatal; Neonatal Mortality; Neuraxis; Neuroglia; Neurologic; Neurons; Neuropathogenesis; Newborn Infant; Pathogenesis; Pathway interactions; Peripheral Nervous System; Phosphotransferases; Play; Population; Proteins; Recombinants; Role; Serotyping; Severity of illness; Simplexvirus; Transgenic Mice; United States; Vagina; Viral Proteins; Virulence; Virus; Virus Diseases; Virus Replication; attenuation; cell type; genital infection; in vivo; inhibition of autophagy; mortality; mouse model; mutant; neonatal brain; neonatal morbidity; neonate; neurodevelopment; neurotropic virus; neurovirulence; novel therapeutic intervention; pathogen; public health relevance; research study; response; targeted treatment; virus pathogenesis; working group

 DESCRIPTION (provided by applicant): Infection with herpes simplex virus (HSV) in adults is often subclinical, but in the newborn HSV is a significant cause of mortality and morbidity. Although differences in the immune response between the developing brain and the adult have been implicated in the increased severity of disease in the neonate, the precise reasons for this difference are unknown. The HSV protein γ34.5 is often described as the "neurovirulence factor" during HSV central nervous system (CNS) infection due to the finding that the deletion of this gene results in a significantly attenuated virus that has decreased replication in neurons. Prior studies have shown that the HSV γ34.5 protein is central to countering the type-I interferon response initiated by the host cell through multiple domains that function to (i) counter host-translational arrest through PKR, (ii) inhibit the TANK-binding kinase pathway, and (iii) inhibit te autophagic response through a domain that binds its initiating protein, beclin-1. Inhibition of autophagy by many neurotropic viruses, including HSV, is a critical function for pathogenesis in neurons, which use autophagy as a method to control viral replication and avoid a potentially devastating cytolytic response. In a murine model of adult HSV encephalitis, a beclin-1 binding domain (BBD) deficient γ34.5 mutant HSV-1 is unable to inhibit autophagy and is severely neuroattenuated in adult mice. Autophagy is up-regulated in the neonatal brain after birth and it also plays a critical role in neurodevelopment. My preliminary data suggests that unlike in the adult, the beclin-1-binding function of γ34.5 is dispensable for the pathogenesis of HSV in a model of neonatal encephalitis. However, deletion of the entire γ34.5 gene from HSV-1 still results in neuroattenuation in the neonatal brain. Therefore, I hypothesize that γ34.5 confers the neurovirulence of HSV in the neonate through a mechanism that is distinct from the inhibition of autophagy. Although autophagy appears to play a cytoprotective role in an adult model of HSV encephalitis, the role of autophagy in the unique environment of the neonatal brain has not yet been investigated. Recent work by groups investigating neonatal hypoxic-ischemic injury has demonstrated that dysregulated autophagy may contribute to increased apoptotic cell death in the neonatal brain. My preliminary data suggests an association between markers of activated autophagy and apoptosis in infected regions of the neonatal brain. Thus, I hypothesize that unlike in the adult, autophagy does not protect the newborn brain from HSV infection and activated autophagy leads to increased apoptotic cell death. I will elucidate the critical determinants of neuropathogenesis in the neonate compared to the adult using several mutant viruses that have been deleted in the γ34.5 regions critical for host-cell interaction. Using wild type and autophagy knockout mice, I will investigate the activation of autophagy in the infected neonatal CNS and the contribution of autophagy to apoptotic cell death.

 描述（由申请人提供）：成人单纯疱疹病毒（HSV）感染通常是亚临床的，但在新生儿中HSV是死亡和发病的重要原因。虽然发育中的大脑和成人之间的免疫反应差异与新生儿疾病严重程度的增加有关，但这种差异的确切原因尚不清楚。HSV蛋白γ34.5通常被描述为HSV中枢神经系统（CNS）感染期间的“神经毒力因子”，因为发现该基因的缺失导致显著减毒的病毒，其在神经元中的复制减少。先前的研究已经表明，HSV γ34.5蛋白是通过多个结构域对抗由宿主细胞引发的I型干扰素应答的核心，所述多个结构域的功能是（i）通过PKR对抗宿主翻译停滞，（ii）抑制TANK结合激酶途径，和（iii）通过结合其起始蛋白beclin-1的结构域抑制自噬应答。许多嗜神经病毒（包括HSV）对自噬的抑制是神经元发病机制的关键功能，神经元使用自噬作为控制病毒复制和避免潜在破坏性细胞溶解反应的方法。在成年HSV脑炎的小鼠模型中，beclin-1结合结构域（BBD）缺陷型γ34.5突变型HSV-1不能抑制自噬，并且在成年小鼠中严重神经衰减。自噬在出生后的新生儿大脑中上调，并且在神经发育中也起着关键作用。我的初步数据表明，与成人不同，γ34.5的beclin-1结合功能与新生儿脑炎模型中HSV的发病机制无关。然而，从HSV-1中缺失整个γ34.5基因仍然导致新生儿脑中的神经衰减。因此，我假设γ34.5赋予了 通过与抑制自噬不同的机制，在新生儿中抑制HSV的神经毒力。 虽然自噬似乎在HSV脑炎的成人模型中发挥细胞保护作用，但自噬在新生儿脑的独特环境中的作用尚未被研究。研究新生儿缺氧缺血性损伤的小组最近的工作表明，失调的自噬可能有助于增加新生儿脑中的凋亡细胞死亡。我的初步数据表明，在新生儿大脑的感染区域，激活的自噬标记物和细胞凋亡之间存在关联。因此，我假设与成人不同，自噬不能保护新生儿大脑免受HSV感染，激活的自噬导致凋亡细胞死亡增加。我将使用几种在宿主细胞相互作用的关键γ34.5区域缺失的突变病毒，阐明新生儿与成人相比神经发病机制的关键决定因素。使用野生 型和自噬基因敲除小鼠，我将研究感染的新生儿CNS中自噬的激活和自噬对凋亡细胞死亡的贡献。