GENE REPLACEMENT THERAPY AND THE IMMUNE SYSTEM

基因替代疗法和免疫系统

• 批准号: 7885360
• 负责人: Hildegund C. J. Ertl
• 金额: $ 35.49万
• 依托单位: WISTAR INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7885360
• 关键词: Adenoviruses; Adjuvant; Affect; Animals; Antigen-Presenting Cells; Antigens; Canis familiaris; Capsid; Cells; Cellular Immunity; Childhood; Dendritic Cells; Dependovirus; Gene Transfer; Genes; Genome; Goals; Helper Viruses; Hemophilia A; Hemophilia B; Hepatic; Hepatocyte; Hepatotoxicity; Herpesviridae; Human; Immune; Immune response; Immune system; Immunity; Immunocompetent; Impairment; In Situ; Inbred Mouse; Infection; Inflammatory; Longevity; Mediating; Modeling; Mus; Patients; Population; Primates; Production; Reaction; Recombinants; Rodent; Sequence Homology; Serotyping; Staging; System; T-Lymphocyte; T-Lymphocyte Epitopes; Testing; Transduction Gene; Transgenes; Viral; Viral Vector; Virus; adeno-associated viral vector; base; experience; gene replacement; gene replacement therapy; gene therapy; human subject; immunogenic; immunogenicity; mouse model; neutralizing antibody; nonhuman primate; preclinical study; research study; response; therapeutic protein; vector

The goal of this project is to elucidate the effect of pre-existing adeno-associated virus-2-specific T cell-mediated immunity on hepatic rAAV vector-mediated gene transfer. Recombinant (r) AAV-2 vectors have yielded promising results in gene replacement therapy of immunocornpetent experimental animals suggesting that they are comparatively poorly immunogenic. Humans are generally exposed to AAV-2 antigens during childhood through infection by AAV-2 accompanying another virus, a so-called helper virus, such as an adenovirus or a herpes virus. Under circumstances where the poorly immunogenic AAV-2 is introduced with a helper virus that causes a strong inflammatory reaction, the helper virus is expected to provide an adjuvant effect that should facilitate the induction of a strong adaptive immune response to antigens of AAV-2. Human subjects unlike experimental rodents or canines are thus likely to have antigen-experienced T cells to AAV-2 that may become activated more readily upon rAAV-2-mediated gene transfer than has been appreciated by pre-clinical studies conducted thus far. Potentially confounding this problem is that AAV-2 persists in humans in a form that suggests that its genome may continue to be transcribed. Even very low levels of persistent AAV-2 antigen would maintain the immune system at a heightened stage of activation. Pre-existing T cell-mediated immunity to AAV-2 may also affect the use of simian AAVs for gene replacement therapy due to shared T cell epitopes between human and simian origin AAVs. One of the challenges of this application is to mimic natural AAV infection of humans in an experimental small animal species suited to conduct an in depth study of immune responses. For this, inbred mice will be used although they are not natural hosts for AAV-2 or its natural helper viruses. To overcome this limitation we developed and will continue to refine in aim 1 an experimental system to induce AAV capsid-specific T cell responses in mice, which resemble functionally those in human subjects. In aim 2, we will characterize the immune response to AAV-2 capsid in depth using the most suitable mouse model. In aim 3, we will use the model to test the effect of pre-existing immunity to AAV-2 on the efficacy, immunogenicity and longevity of rAAV-2-mediated gene transfer. Experiments will be extended in aim 4 to a vector system based on simianderived AAV-8 to assess if a heterologous rAAV vector can overcome pre-existing immunity to AAV-2.

本项目的目标是阐明预先存在的腺相关病毒2型特异性T细胞介导的 肝脏rAAV载体介导的基因转移的免疫。重组（r）AAV-2载体具有 在免疫活性实验动物的基因替代治疗中取得了有希望的结果 表明它们的免疫原性相对较差。人类通常暴露于AAV-2 抗原在儿童期通过伴随另一种病毒的AAV-2感染，所谓的辅助病毒， 如腺病毒或疱疹病毒。在免疫原性差的AAV-2被感染的情况下， 引入一种引起强烈炎症反应的辅助病毒，辅助病毒预计将 提供佐剂作用，其应促进诱导强适应性免疫应答， AAV-2的抗原。因此，与实验啮齿类动物或犬科动物不同，人类受试者可能具有抗原经历性。 T细胞与AAV-2的结合，在rAAV-2介导的基因转移后可能更容易被激活 比迄今为止进行的临床前研究所认识到的要多。可能混淆这个问题的是 AAV-2在人类中以某种形式存在，这表明其基因组可能继续转录。甚至 非常低水平的持续性AAV-2抗原将使免疫系统维持在增强的阶段， activation.预先存在的T细胞介导的对AAV-2的免疫也可能影响猿AAV用于基因表达的用途。 由于人和猿猴来源的AAV之间共有的T细胞表位，因此可以使用替代疗法。之一 该应用的挑战是在实验小动物中模拟人的天然AAV感染 适合进行深入研究免疫反应的物种。为此，将使用近交系小鼠 尽管它们不是AAV-2或其天然辅助病毒的天然宿主。为了克服这一限制，我们 在目标1中，开发并将继续完善诱导AAV衣壳蛋白特异性T细胞的实验系统 在小鼠中的反应，其在功能上类似于人类受试者中的反应。在目标2中，我们将描述 使用最合适的小鼠模型深入研究对AAV-2衣壳的免疫应答。在目标3中，我们将使用 该模型用于测试预先存在的对AAV-2的免疫性对AAV-2的功效、免疫原性和寿命的影响。 rAAV-2介导的基因转移。实验将在aim 4中扩展到基于simianderived的向量系统 AAV-8来评估异源rAAV载体是否可以克服对AAV-2的预先存在的免疫性。