Theiler's virus-induced aoptosis: A mechanism for CNS virus persistence

泰勒病毒诱导的细胞凋亡：中枢神经系统病毒持续存在的机制

• 批准号: 8016588
• 负责人: HOWARD Lee LIPTON
• 金额: $ 33.66万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-02-01 至 2014-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8016588
• 关键词: Address; Apical; Apoptosis; Apoptotic; Attenuated; Autoimmune Diseases; Autoimmune Process; Autoimmunity; CD4 Positive T Lymphocytes; Capsid Proteins; Cardiovirus; Cell Death; Cell Line; Cell surface; Cells; Central Nervous System Infections; Cessation of life; D Cells; Demyelinating Diseases; Demyelinations; Elements; Experimental Animal Model; Family Picornaviridae; Fostering; Immune; Immune response; Immunity; In Vitro; Infection; Inhibition of Apoptosis; Integration Host Factors; Lytic; Mammalian Cell; Mediating; Mitochondria; Modeling; Mouse Strains; Multiple Sclerosis; Mus; Necrosis; Neuraxis; Neurons; Nonstructural Protein; Noxae; Oligodendroglia; Organism; Pathway interactions; Phagocytosis; Population; Process; Production; Proteins; RNA Virus Infections; RNA Viruses; Replicon; Resistance; Rodent; Signal Transduction; System; T cell response; TMEV; Transgenic Mice; Viral; Viral Proteins; Virulent; Virus; Virus Diseases; Virus Replication; Work; arm; bean; extracellular; genetic variant; in vitro Model; in vivo; inhibitor/antagonist; killings; macrophage; member; neurovirulence; neutralizing antibody; public health relevance; research study

DESCRIPTION (provided by applicant): Theiler's murine encephalomyelitis virus (TMEV) is a highly cytolytic RNA virus that produces persistent central nervous system (CNS) infection and immune-mediated demyelination in susceptible strains of mice. TMEV infection provides a relevant experimental animal model for multiple sclerosis. In contrast to persistence of non-cytolytic RNA viruses in which the host cell survives, persistence of lytic RNA viruses in which an infected cell dies requires continuous cell- to-cell spread in order to maintain the infection. In this circumstance, the target cell in which the virus persists ideally should be renewable. The infection should not be highly productive; however, virus-specific host immune responses may control a more productive infection anyway. Macrophages are the principal virus reservoir and provide an in vitro model for TMEV persistence in the mouse CNS. TMEV infected macrophages undergo apoptosis and restrict virus production (<10 pfu/cell), in contrast to infection in other rodent cells, including neurons and oligodendrocytes, where necrotic cell death is associated with high virus yields (200-500 pfu/cell). TMEV infection is required to induce apoptosis in murine macrophages since UV- inactivated virus adsorbed to the cell surface to initiate infection does not induce apoptosis. We have shown that TMEV infection induces apoptosis through the intrinsic pathway that is Bax- mediated and severely restricts infectious virus production in murine macrophages. Our working hypothesis is that TMEV-induced apoptosis is a host cell-specific mechanism providing a means of spreading virus to uninfected macrophages that phagocytose apoptotic remnants containing infectious virus. To understand how TMEV infection triggers apoptosis in murine macrophages and restricts infectious virus production, four specific aims are proposed: 1) finish the identification of upstream signals (apical to the mitochondrion) involved in the intrinsic apoptotic pathway during TMEV virus infection in M1-D macrophages and determine potential differences in apoptosis in primary macrophages from resistant and susceptible strains of mice; 2) inhibit apoptosis in infected mice to assess the effect on TMEV CNS persistence, virus-specific CD4+ T cell responses and demyelinating disease, and examine the effect in transgenic mice deficient in p53 and Noxa on CNS persistence and demyelinating disease; 3) identify potential virus "triggers" of apoptosis by expressing TMEV nonstructural proteins L and 3CD in mammalian cells, and determine whether TMEV replicons in which the capsid proteins are deleted can induce apoptosis; and 4) investigate the mechanism of loss of infectious virus in murine macrophages that is associated with onset of apoptosis. PUBLIC HEALTH RELEVANCE: The notion that multiple sclerosis (MS) is an autoimmune disease is widely accepted as fact. While MS is undoubtedly immune-mediated, an autoimmune mechanism remains unproven. Circumstantial evidence points to a persistent virus infection in MS. Moreover, immune- mediated damage can result from a virus infection in which the host immune response is directed to virus proteins rather than self proteins (autoimmunity). Theiler's murine encephalomyelitis virus (TMEV) produces a persistent central nervous system infection and immune-mediated demyelination in susceptible strains of mice, providing a relevant experimental animal model for MS. TMEV persistence is needed to drive the demyelinating disease process, but just how this virus that rapidly kills infected cells is able to perpetuate the infection is not known. This proposal addresses a mechanism of TMEV persistence, programmed cell death also termed apoptosis, which decreases virus production (may be required for persistence of virulent virus) and also fosters cell-to-cell virus spread (required for persistence in the presence of host immunity).

描述（由申请人提供）：泰勒氏鼠脑脊髓炎病毒（TMEV）是一种高度溶细胞性 RNA 病毒，可在易感小鼠品系中产生持续的中枢神经系统（CNS）感染和免疫介导的脱髓鞘。 TMEV感染为多发性硬化症提供了相关的实验动物模型。与宿主细胞存活的非溶细胞性RNA病毒的持续存在相反，受感染细胞死亡的溶菌性RNA病毒的持续存在需要持续的细胞间传播以维持感染。在这种情况下，理想情况下病毒持续存在的靶细胞应该是可再生的。感染不应具有高生产力；然而，病毒特异性的宿主免疫反应无论如何都可能控制更有效的感染。巨噬细胞是主要的病毒库，为 TMEV 在小鼠中枢神经系统中的持续存在提供了体外模型。 TMEV感染的巨噬细胞会发生凋亡并限制病毒产生（<10 pfu/细胞），这与其他啮齿动物细胞（包括神经元和少突胶质细胞）的感染相反，其中坏死性细胞死亡与高病毒产量（200-500 pfu/细胞）相关。 TMEV 感染是诱导小鼠巨噬细胞凋亡所必需的，因为吸附到细胞表面以启动感染的紫外线灭活病毒不会诱导细胞凋亡。我们已经表明，TMEV 感染通过 Bax 介导的内在途径诱导细胞凋亡，并严重限制小鼠巨噬细胞中感染性病毒的产生。我们的工作假设是，TMEV 诱导的细胞凋亡是一种宿主细胞特异性机制，提供了一种将病毒传播到未感染的巨噬细胞的方法，巨噬细胞吞噬含有感染性病毒的细胞凋亡残余物。为了了解TMEV感染如何引发小鼠巨噬细胞凋亡并限制感染性病毒的产生，提出了四个具体目标：1）完成M1-D巨噬细胞中TMEV病毒感染过程中涉及内在凋亡途径的上游信号（线粒体顶端）的鉴定，并确定原代巨噬细胞中耐药和敏感巨噬细胞凋亡的潜在差异。 小鼠品系； 2) 抑制感染小鼠的细胞凋亡，以评估对TMEV CNS持久性、病毒特异性CD4+ T细胞反应和脱髓鞘疾病的影响，并检查缺乏p53和Noxa的转基因小鼠对CNS持久性和脱髓鞘疾病的影响； 3)通过在哺乳动物细胞中表达TMEV非结构蛋白L和3CD来鉴定潜在的细胞凋亡的病毒“触发因素”，并确定衣壳蛋白被删除的TMEV复制子是否可以诱导细胞凋亡； 4) 研究小鼠巨噬细胞中感染性病毒丢失与细胞凋亡发生相关的机制。 公众健康相关性：多发性硬化症 (MS) 是一种自身免疫性疾病的观念已被广泛接受。虽然多发性硬化症无疑是免疫介导的，但自身免疫机制尚未得到证实。间接证据表明多发性硬化症存在持续的病毒感染。此外，免疫介导的损伤可能是由病毒感染引起的，其中宿主免疫反应针对病毒蛋白而不是自身蛋白（自身免疫）。泰勒氏鼠脑脊髓炎病毒（TMEV）在易感小鼠品系中产生持续的中枢神经系统感染和免疫介导的脱髓鞘，为多发性硬化症提供了相关的实验动物模型。 TMEV 的持久性是驱动脱髓鞘疾病过程所必需的，但这种快速杀死受感染细胞的病毒如何能够使感染永久存在尚不清楚。该提案解决了 TMEV 持久性的机制，程序性细胞死亡也称为细胞凋亡，它减少病毒产生（可能是强毒病毒持久性所必需的），并且还促进细胞间病毒传播（在宿主免疫存在的情况下持久性所需）。