Pathogenesis Of Enteric Viral Hepatitis

肠道病毒性肝炎的发病机制

• 批准号: 7964477
• 负责人: Robert H. Purcell
• 金额: $ 104.08万
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7964477
• 关键词: Acute Hepatitis; Adult; Animal Model; Animals; Antibodies; Asia; Attenuated; Base Pairing; Birds; Cell Culture Techniques; Chickens; Comparative Study; Complementary DNA; Detection; Developed Countries; Developing Countries; Development; Diagnostic tests; Double-Stranded RNA; Engineering; Enteral; Family suidae; Genes; Hepatitis A; Hepatitis A Vaccines; Hepatitis A Virus; Hepatitis C; Hepatitis C virus; Hepatitis E; Hepatitis E virus; Hepatitis Viruses; Immune response; In Vitro; Infection; Interferons; International; Laboratory Animals; Life; Light; Marketing; Microarray Analysis; Middle East; Modeling; Molecular; Molecular Analysis; Molecular Probes; Movement; Mutation; Northern Africa; Pan Genus; Pathogenesis; RNA Viruses; Replicon; Serological; System; United States; Up-Regulation; Vaccines; Variant; Viral; Viral hepatitis; Virulence; Virulent; Virus; Virus Diseases; attenuation; base; in vivo; interest; nonhuman primate; pathogen; response; tool

We have studied the pathogenesis of viral hepatitis and the molecular basis for virulence and attenuation of these important pathogens. We have shown previously that virulence and attenuation of hepatitis A virus (HAV) are controlled principally by two genes: VP1/2A and 2C. However, attenuating mutations are strongly selected against in vivo, resulting in the emergence of virulent variants. This has important implications for the development of live attenuated hepatitis A vaccines. The pathogenesis of hepatitis A is also being studied in the chimpanzee model by microarray analysis. Both innate and adaptive responses have been recorded. Interestingly, HAV does not trigger as robust an up-regulation of certain interferon stimulated genes as HCV and HDV infections. This is surprising because HAV and HCV are both single-stranded RNA viruses with a double-stranded replicative form and HDV is a single-stranded virus with extensive base pairing that is perceived as double-stranded RNA. Specifically, in FY 2009, we compared the innate and adaptive immune responses to HAV infection in several experimentally infected chimpanzees, including animals that received virulent inocula and those that were infected with attenuated strains of HAV. Animals infected with virulent strains had a robust innate immune response (although not as robust as that seen in HCV-infected chimpanzees), whereas the response was less marked in the attenuated infections. Interestingly, innate immune responses were abbreviated in the latter chimpanzees, but detection of the innate immune response was almost as sensitive a diagnostic test of infection as was detection of specific serologic or molecular probes of HAV infection. The adaptive immune responses were also present, but not as robust as the adaptive immune responses in HCV infections of chimpanzees. It will be important to search for viral mechanisms of control that may block some of these systems. Although rare in the United States, hepatitis E is the single most important cause of acute hepatitis among adults throughout Asia, the Middle East and North Africa. Like most of the hepatitis viruses, it replicates poorly or not at all in cell culture and cannot be transmitted to small laboratory animals. We have developed replicons for the study of HEV in vitro; these tools are permitting a detailed molecular analysis of viral replication that can be confirmed in vivo with molecularly engineered infectious cDNA clones of the virus. In addition, with colleagues, we are developing small animal models (swine HEV in swine, avian HEV in chickens) that, with nonhuman primate models of HEV, provide an unprecedented opportunity for studying the comparative pathogenesis of hepatitis E viruses. Finally, hepatitis E has also been studied by microarray and a brisk innate but weak adaptive immune response has been seen. Specifically, in FY 2009, we compared the innate and adaptive immune responses of several chimpanzees to experimental HEV infections with those observed in chimpanzees that had been experimentally infected with HCV or HAV. In comparison with those infections, HEV infections were characterized by an abbreviated and somewhat shortened adaptive immune response. This is particularly interesting in light of other observations that antibody titers tend to diminish more rapidly in HEV infections than in infections with the other hepatitis viruses.

我们研究了病毒肝炎的发病机理以及这些重要病原体的毒力和衰减的分子基础。我们先前已经证明，肝炎A病毒（HAV）的毒力和衰减主要由两个基因控制：VP1/2A和2C。然而，强烈选择衰减突变与体内的突变，从而导致有毒变体的出现。这对肝炎A疫苗的发育具有重要意义。通过微阵列分析，也在黑猩猩模型中研究了肝炎A的发病机理。先天性和自适应反应都已记录。有趣的是，HAV不会像HCV和HDV感染那样触发某些干扰素刺激基因的强大上调。这是令人惊讶的，因为HAV和HCV都是具有双链复制形式的单链RNA病毒，HDV是一种单链病毒，具有广泛的碱基对，被视为双链RNA。 具体而言，在2009财年，我们比较了几种实验感染的黑猩猩对HAV感染的先天和适应性免疫反应，包括接受强烈接种物的动物以及受到衰减HAV菌株的感染的动物。 感染毒株的动物具有强大的先天免疫反应（尽管不像HCV感染的黑猩猩那样强大），而在减毒感染中的反应较低。 有趣的是，在后者的黑猩猩中缩写了先天免疫反应，但是对先天免疫反应的检测几乎是对感染的诊断测试的敏感性，就像检测到特定的血清学或分子探针的HAV感染。 也存在适应性免疫反应，但不像黑猩猩的HCV感染中的适应性免疫反应那样健壮。搜索可能阻止其中一些系统的控制的病毒机制将很重要。 尽管在美国很少见，但丙型肝炎是亚洲，中东和北非成年人中急性肝炎的最重要原因。 像大多数肝炎病毒一样，它在细胞培养中复制或根本不复制，不能传播到小型实验室动物。我们已经开发了用于体外HEV研究的复制子；这些工具允许对病毒复制进行详细的分子分析，该分子可以用该病毒的分子传染性cDNA克隆在体内证实。 此外，与同事一起，我们正在开发小型动物模型（猪中的猪螺旋，鸡在鸡中），借助HEV的非人类灵长类动物模型，为研究乙型肝炎病毒病毒的比较发病机理提供了前所未有的机会。 最后，微阵列还研究了丙型肝炎，并且已经看到了既有的天生，又有弱适应性免疫反应。 具体而言，在2009财年，我们比较了几只黑猩猩的先天和适应性免疫反应与实验性HEV感染与在实验感染了HCV或HAV的黑猩猩中观察到的那些。 与这些感染相比，HEV感染的特征是缩写和略有缩短的适应性免疫反应。 鉴于其他观察结果，抗体滴度在HEV感染中比其他肝炎病毒感染更快地减少了抗体滴度。