Human mechanisms of virus persistence in an AAV-based mouse model of chronic HBV infection

项目摘要 慢性B型肝炎病毒（HBV）感染与无效的T细胞应答相关， 病毒虽然慢性B型肝炎中T细胞功能障碍的确切机制尚不清楚，但先前的研究表明， 使用急性和慢性HBV患者的血液和肝组织的研究已经确定了一些关键的 免疫机制，可能有助于这种不良的免疫反应。这些机制包括 肝内自然杀伤（NK）细胞杀死HBV特异性T细胞，这是肝内的一般致耐受性环境。 肝脏表现为免疫抑制性免疫细胞、细胞因子和代谢途径， 通过抑制性受体信号通路和衰竭来抑制T细胞功能。乙型肝炎病毒宿主的研究 慢性B型肝炎免疫治疗的发展受到阻碍 缺乏慢性感染的生理动物模型。一种新的HBV复制小鼠模型， 最近描述的是基于腺相关病毒（AAV）介导的肝脏转导， HBV基因组，导致持续的病毒复制和对HBV抗原的免疫耐受。相比 在HBV复制的其他小鼠模型中，AAV-HBV模型具有重要的优势，包括生理学上的优势。 肝内免疫引发、技术简便性和可重复性、外周T和B细胞对HBV的耐受性，以及 研究病毒从肝脏中清除的能力使用这个模型，我们将测试假设， 治疗性疫苗功效可通过操纵免疫功能障碍的机制来增强， 病毒清除我们一般的方法将是将联合收割机AAV-HBV转导与基因修饰小鼠相结合 和抗体介导的耗竭/阻断，以评估免疫细胞、细胞因子和调节因子的重要性。 在治疗性免疫后，诱导功能性CD 8 + T细胞应答和控制HBV的途径。 为了评估我们的假设，我们将实现三个具体目标。首先，我们将评估HBV的抑制作用- NK细胞的特异性T细胞。其次，我们将定义调节细胞，细胞因子和代谢途径的作用。 第三，我们将评估T细胞抑制性受体功能和耗竭。将获得的知识， 这项研究将在两个重要方面影响该领域。首先，它将提供新的机械洞察力， T细胞功能障碍与HBV持久性之间的关系，并为未来的研究奠定坚实的基础 使用AAV-HBV模型来更好地理解在人类中观察到的病毒-宿主相互作用。第二、 它将为治疗慢性HBV感染的潜在方法揭示新的免疫靶点。

PROJECT SUMMARY Chronic hepatitis B virus (HBV) infection is associated with an ineffective T cell response that fails to control the virus. While the precise mechanism of T cell dysfunction in chronic hepatitis B is not well understood, prior studies using blood and liver tissue from acute and chronic HBV patients have identified a number of critical immunological mechanisms that may contribute to this poor immune response. These mechanisms include the killing of HBV-specific T cells by liver-resident natural killer (NK) cells, a general tolerogenic environment in the liver that is manifested by immunosuppressive immune cells, cytokines, and metabolic pathways, and the loss of T cell function through inhibitory receptor signaling pathways and exhaustion. The study of HBV-host interactions and the development of new curative immunotherapies for chronic hepatitis B have been hampered by the lack of physiological animal models for chronic infection. A new mouse model of HBV replication was recently described that is based on adeno-associated virus (AAV)-mediated transduction of the liver with the HBV genome, which leads to persistent virus replication and immune tolerance to HBV antigens. Compared to other mouse models of HBV replication, the AAV-HBV model has important advantages, including physiological intrahepatic immune priming, technical ease and reproducibility, peripheral T and B cell tolerance to HBV, and the ability to study virus elimination from the liver. Using this model, we will test the hypothesis that HBV therapeutic vaccine efficacy can be enhanced by manipulating mechanisms of immune dysfunction to promote viral clearance. Our general approach will be to combine AAV-HBV transduction with genetically modified mice and antibody-mediated depletion/blockade to evaluate the importance of immune cells, cytokines, and regulatory pathways for eliciting functional CD8+ T cell responses and controlling HBV following therapeutic immunization. To evaluate our hypothesis, we will carry out three specific aims. First, we will assess the inhibition of HBV- specific T cells by NK cells. Second, we will define the role of regulatory cells, cytokines, and metabolic pathways. Third, we will evaluate T cell inhibitory receptor function and exhaustion. The knowledge that will be gained from this research will impact the field in two important ways. First, it will provide new mechanistic insight into the relationship between T cell dysfunction and HBV persistence, and form a strong foundation for future studies using the AAV-HBV model to better understand the virus-host interactions that are observed in humans. Second, it will reveal new immunotherapeutic targets for potential approaches to cure chronic HBV infection.