The Role of Transferrin Receptor 1 in Hepatitis C virus Entry

描述(申请人提供)：丙型肝炎病毒(丙型肝炎病毒)感染全球超过1.7亿人，导致急慢性肝炎和肝细胞癌。由于没有疫苗可用于预防丙型肝炎病毒感染，而且只有一小部分慢性感染患者对当前的治疗方案有反应，因此迫切需要新的有效的丙型肝炎病毒抗病毒药物。自从发现丙型肝炎病毒以来，阻碍丙型肝炎病毒研究的一个主要障碍是缺乏强大的细胞培养和小动物感染模型。虽然在过去的5年中，随着第一个强大的体外丙型肝炎病毒感染系统的建立，在体外取得了显著的进展，但仍然需要开发一个强大的、广泛可用的小动物模型来进行病理学和免疫学研究。进入丙型肝炎病毒不仅代表了一个有希望的多方面的药物发现机会，但我们还没有确定所有足以导致丙型肝炎病毒感染的因素，包括决定传染性丙型肝炎病毒进入的限制性肝脏和/或物种取向的一个因素(S)。虽然最近发现的人OCLN作为HCVpp进入小鼠细胞所必需的因子似乎使我们更接近了解丙型肝炎病毒的物种趋向性，但迄今为止还没有实现真正的非人类细胞的HCVcc感染，这表明其他进入因子，针对HCVcc，仍然存在。我们的长期目标是了解介导HCVcc进入的细胞和病毒因素，以便为治疗干预确定新的分子靶点，并促进急需的丙型肝炎病毒感染小动物模型的发展。因此，R21应用的目的是阐明一个新发现的假定的丙型肝炎病毒进入因子的作用。具体来说，我们假设细胞转铁蛋白受体1(TfR1)是一种丙型肝炎病毒进入受体，它可能是导致丙型肝炎病毒进入的限制性取向的原因。这一假说是基于已发表的先例证明TfR1是其他病毒的物种特异性受体，以及我们的初步数据表明TfR1是进入丙型肝炎病毒所必需的。因此，我们将追求以下两个特定目标：1)通过确定TfR1何时在丙型肝炎病毒进入过程中起作用以及这种相互作用是否涉及TfR1与丙型肝炎病毒的直接结合来确定TfR1如何以及何时参与丙型肝炎病毒的进入；2)通过鉴定一组细胞以确定TfR1的表达是否赋予非肝脏或非人类细胞对HCVcc的通透性，来确定TfR1是否是丙型肝炎嗜性的决定因素。综上所述，这些信息将奠定基础，使更详细和专门关注的R01应用程序旨在彻底了解丙型肝炎病毒TfR1依赖的进入和/或传染性丙型肝炎病毒小鼠模型的发展。

DESCRIPTION (provided by applicant): Hepatitis C virus (HCV) infects more than 170 million people worldwide, causing acute and chronic hepatitis and hepatocellular carcinoma. With no vaccine available to protect against HCV infection and only a subset of chronically infected patients responding to current treatment options, there is an immediate need for new effective HCV antivirals. Since its discovery in 1989, a major obstacle impeding HCV research has been the lack of robust cell culture and small animal infection models. While significant in vitro advancement has been made in the last 5 years with the development of the first robust in vitro HCV infection system, the development of a robust and widely available small animal model for pathology and immunology studies is still needed. HCV entry not only represents a promising multi-faceted opportunity for drug discovery, but we have yet to identify all the factors sufficient for HCV infection including the one(s) that dictate the restricted liver and/or species tropism of infectious HCV entry. While the recent discovery of human OCLN as a factor necessary for HCVpp entry into mouse cells appears to have brought us one step closer to understanding HCV species tropism, to date authentic HCVcc infection of non-human cells has not been achieved suggesting that other entry factors, specific for HCVcc, still exist. Our long term goal is to understand the cellular and viral factors that mediate HCVcc entry in order to identify novel molecular targets for therapeutic intervention and facilitate the much needed development of small animal models of HCV infection. As such, the objective of this R21 application is to elucidate the role of a newly identified putative HCV entry factor. Specifically, we hypothesize that the cellular transferrin receptor 1 (TfR1) is an HCV entry receptor and that it may be responsible for the restricted tropism of HCV entry. This hypothesis is based on published precedents demonstrating that TfR1 functions as a species specific receptor for other viruses and our preliminary data which demonstrate that TfR1 is required for HCV entry. Hence, we will pursue the following two specific aims: 1) To characterize how and when TfR1 participates in HCV entry by determining when TfR1 acts in the HCV entry process and if that interaction involves direct TfR1 binding to HCV and 2) To determine whether TfR1 is a determinant of HCV tropism by characterizing a panel of cells to determine if TfR1 expression confers HCVcc permissiveness to non-hepatic or non-human cells. Taken together, this information will lay the groundwork that will enable a more detailed and specifically focused R01 application aimed at thoroughly understanding HCV TfR1-dependent entry and/or the development of an infectious HCV mouse model.