A Chicken Model to Study Hepatitis E Virus Pathogenesis

描述(申请人提供)：戊型肝炎病毒(HEV)是戊型肝炎的病原体，在发展中国家是一个重要的公共卫生问题。HEV在美国也是地方病。据报道，受感染的孕妇的死亡率高达20%。由于缺乏实用的动物模型和体外细胞培养系统，对HEV的复制和致病机制了解较少，目前尚无针对HEV的疫苗。这项建议是基于我们最近在2000年从鸡身上发现了一种新的禽类HEV，并在1997年从猪身上发现了一种新的猪HEV。禽HEV和猪HEV在抗原性和基因上都与人HEV有亲缘关系。我们已经证明，猪HEV感染非人类灵长类动物，美国人HEV毒株感染猪，猪饲养员有感染人畜共患HEV的风险。这项建议的核心假设是，戊型肝炎是一种人畜共患病，与猪一样，鸡也是HEV的动物宿主，鸡是HEV的有用动物模型系统。该项目的长期目标是通过以鸡的HEV感染作为动物模型系统，通过使用禽-猪、禽-人和猪-人HEV嵌合体来确定对这些过程具有重要功能的基因，从而定义和了解HEV复制和致病的机制。在这项研究中，我们的目标是：1)在同源模型(鸡的HEV感染)中系统地描述HEV的复制和致病过程；2)确定HEV在感染鸡中的起始和肝外复制位置；3)构建具有感染性的禽HEV基因克隆，为进一步利用HEV嵌合体研究HEV基因的结构和功能关系奠定基础；4)评估禽HEV感染人畜共患病的潜在风险。这将通过使用标准技术来完成，包括原位杂交、聚合酶链式反应、克隆和测序、基因表达以及血清学和病理学方法。这些研究将极大地促进我们对HEV复制机制、发病机制和自然病程的理解。所获得的信息将对开发HEV研究的小动物模型以及制定预防和控制这一重要疾病的策略非常有用。

DESCRIPTION (provided by applicant): Hepatitis E virus (HEV), the causative agent of hepatitis E, is an important public health problem in developing countries. HEV is also endemic in the U.S. The mortality rate is reportedly up to 20% in infected pregnant women. Due to the lack of a practical animal model and an in vitro cell culture system, the replication and pathogenesis of HEV is poorly understood and a vaccine for HEV is still not available. This proposal is based on our recent discoveries of a novel avian HEV from chickens in 2000 and a novel swine HEV from pigs in 1997. Both avian HEV and swine HEV are antigenically and genetically related to human HEV. We have shown that swine HEV infects non-human primates and a U.S. human strain of HEV infects pigs, and that pig handlers are at risk of zoonotic HEV infection. Avian HEV causes a hepatitis disease in chickens that is similar to human hepatitis E. The central hypotheses of this proposal are that hepatitis E is a zoonosis and that, like pigs, chickens are also animal reservoirs for HEV, and that chickens are a useful animal model system for HEV. The long-term objectives of the project are to define and understand the mechanism of HEV replication and pathogenesis by using HEV infection in chickens as an animal model system and by using avian-swine, avian-human and swine-human HEV chimeras to identify genes that are functionally important for these processes. In this proposal, we aim to: 1) systematically characterize the course of HEV replication and pathogenesis in a homologous model (avian HEV infection in chickens), 2) to identify the initial and extrahepatic sites of HEV replication in infected chickens, 3) to construct an infectious cDNA clone of avian HEV for future study of the structural and functional relationship of HEV genes by using HEV chimeras, and 4) to evaluate the potential risk of zoonotic infection by avian HEV. This will be accomplished by using standard techniques including in situ hybridization, PCR, cloning and sequencing, gene expression, and serological and pathological methods. The proposed studies will significantly advance our understanding of the mechanisms of HEV replication, pathogenesis and natural history. The information gained will be very useful for developing small animal models for HEV research and for devising strategies to prevent and control this important disease.