Pathogenesis Of Viral Hepatitis

病毒性肝炎的发病机制

• 批准号: 6987075
• 负责人: Robert H. Purcell
• 金额: --
• 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/6987075
• 关键词: Callithricidae; Hepatovirus; Macaca mulatta; Pan; cellular immunity; chronic disease /disorder; clinical research; hepatitis A; hepatitis A virus; hepatitis B virus group; hepatitis C; hepatitis C virus; hepatitis D; hepatitis D virus; hepatitis E virus; hepatitis virus; human tissue; infant human (0-1 year); interferons; pathologic process; perinatal; tissue /cell culture; virulence; virus genetics; virus infection mechanism; virus replication; Callithricidae; Hepatovirus; Macaca mulatta; Pan; cellular immunity; chronic disease /disorder; clinical research; hepatitis A; hepatitis A virus; hepatitis B virus group; hepatitis C; hepatitis C virus; hepatitis D; hepatitis D virus; hepatitis E virus; hepatitis virus; human tissue; infant human (0-1 year); interferons; pathologic process; perinatal; tissue /cell culture; virulence; virus genetics; virus infection mechanism; virus replication

We are studying the pathogenesis of viral hepatitis and the molecular basis for virulence and attenuation of these important pathogens. Hepatitis A. We have shown previously that virulence and attenuation 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. Hepatitis B. In collaborative studies with Dr. Frank Chisari (Scripps Institute) we have studied in chimpanzees the mechanism by which the host clears a hepatitis B virus infection and the relationship of these mechanisms to clinical disease. We demonstrated that the clearance of the template for HBV synthesis, covalently closed circular HBV DNA, is eliminated from hepatocytes by non-cytolytic mechanisms mediated principally by interferon gamma in the liver. Elimination of residual hepatocytes containing HBV antigens is a later event that is mediated by cytolytic cDNA positive T cells and is temperally related to the hepatitis phase of the infection. The spectrum of virus-induced and immune response-related genes involved in hepatitis B were further studied by microarray analysis of intrahepatic messenger RNAs up-regulated and down-regulated during the course of hepatitis B infections in chimpanzees. Surprisingly, we could not detect evidence of an innate immune response to infection, suggesting that HBV can subvert the host immune response, but we did detect a strong adaptive immune response during the clearance phase of infection; this correlated with the inhibition of viral replication and removal of infected cells described above. Hepatitis C. The genetic heterogeneity of hepatitis C virus is believed to play an important role in its pathogenicity. We have previously examined this relationship by determining the genetic heterogeneity of HCV isolates that were recovered from patients who were infected following transfusion in order to study the early phase of infection and from patients undergoing interferon therapy in order to study changes during the later phase of chronic infection. Distinctive patterns of dynamic change in the sequence of viral clones during the first several weeks of infection were observed and these correlated with the outcome of infection. Similarly, the pattern of dynamic changes in sequence during interferon therapy was predictive of the outcome. These findings may be useful in predicting the outcome of therapy with interferon early in the course of treatment. More recently, we?ve extended these studies to an analysis of HCV sequences in infants and young children who were infected at birth. Although such perinatal transmissions are rare, they do offer an opportunity to study the interaction of the developing host immune response in an immunologically naive infant. Transmission of HCV from mother to infant often is characterized by virtually monoclonal viral infection initially, probably resulting from immunological selection by the mother?s immune system. As the infant mounts its own immunological response the genomic sequence becomes heterogeneous. Thus, the progression from monoclonal to polyclonal viral populations resembles that seen in chimpanzees experimentally infected with monoclonal HCV. Although considerable information has been gained from these longitudinal studies of patients, it is difficult to study the mechanisms of pathogenesis in such systems. Chimpanzees, which are the only animals other than man that are susceptible to infection with HCV, provide an experimental model for studying the interactions of the host and the virus in the pathogenesis of hepatitis C. Collaborative studies with Frank Chisari have demonstrated that, as in hepatitis B virus infections, in hepatitis C virus infections the cellular immune response plays an important rolee in noncytolytic down-regulation of viral replication and cytolytic removal of residual infected cells. These two mechanisms are sequential and overlapping and the former appears to be mediated by interferon gamma and the latter by CD8 positive cells and, perhaps by interferon gamma through its proinflammatory activity. These studies have also revealed that type 1 interferon (interferon alpha/beta)-activated antiviral proteins are expressed in response to the viral infections, but that HCV is resistant to the antiviral activity of this innate immune response. Microarray studies of the host immune responses to viral hepatitis and how the hepatitis viruses attempt to circumvent the responses, are yielding important information on pathogenesis of these diseases, and the studies are being extended to the other hepatitis viruses in order to delineate the comparative pathogenesis of these agents in a single host, the chimpanzee, which is the only non-human host that is acceptable to all human hepatitis viruses. Other studies of hepatitis C in chimpanzees have revealed that a little understood protein, the p7 polypeptide, is critical for infectivity and contains functionally important genotype-specific sequences. This finding provides another potential target for the development of antiviral agents against hepatitis C. Hepatitis D. Hepatitis D virus is a defective virus that requires coinfection with hepatitis B virus for its replication. Although infections with HDV are uncommon, they are associated with severe, rapidly progressing chronic hepatitis leading to death within a few years. In a long-term study of interferon alpha therapy of chronic hepatitis D, a remarkable regression of advanced hepatic cirrhosis was observed. Although reversal of cirrohsis has traditionally been thought not to be possible, this and other studies provide hope for severely affected patients, whose only recourse at this time is liver transplantation. Hepatitis E. 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.

我们正在研究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。丙型肝炎。我们先前已经证明，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。 丙型肝炎B.在与弗兰克·奇萨里（Frank Chisari）博士（Scripps Institute）的合作研究中，我们在黑猩猩中研究了宿主清除乙型肝炎病毒感染以及这些机制与临床疾病的关系的机制。我们证明了HBV合成模板的清除率，即共价闭合的圆形HBV DNA，通过肝脏中主要是由肝脏中的干扰素伽马介导的非胞溶液机制从肝细胞中消除的。消除含有HBV抗原的残留肝细胞是由细胞溶解cDNA阳性T细胞介导的，与感染的乙型肝炎相关。通过在黑猩猩的乙型肝炎感染过程中，通过微阵列分析对肝炎的肝炎诱导的和免疫反应相关的基因进行了对肝内信使RNA的上调和下调的微阵列分析。令人惊讶的是，我们无法检测到对感染的先天免疫反应的证据，这表明HBV可以颠覆宿主的免疫反应，但我们确实在清除感染阶段发现了强烈的适应性免疫反应。这与抑制病毒复制和上述感染细胞的去除有关。 丙型肝炎C.肝炎病毒的遗传异质性在其致病性中起着重要作用。我们先前已经通过确定从输血后感染的患者中回收的HCV分离株的遗传异质性来研究这种关系，以研究感染的早期阶段以及正在接受干扰素治疗的患者，以便研究慢性感染后期的变化。在感染的前几周观察到了病毒克隆序列的动态变化的独特模式，这些模式与感染的结果相关。同样，干扰素治疗期间序列动态变化的模式可以预测结果。这些发现在治疗过程中早期预测干扰素治疗的结果可能很有用。最近，我们将这些研究扩展到对出生时感染的婴儿和幼儿的HCV序列的分析。尽管这种围产期传播很少见，但它们确实提供了研究在免疫天真婴儿中发展宿主免疫反应的相互作用的机会。 HCV从母亲到婴儿的传播通常以实际上是单克隆病毒感染为特征，这可能是由于母亲的免疫系统的免疫学选择而引起的。随着婴儿安装自身的免疫反应，基因组序列变得异质。因此，从单克隆到多克隆病毒群体的进展类似于在黑猩猩中看到的单克隆HCV感染。尽管从患者的这些纵向研究中获得了大量信息，但很难研究这种系统中的发病机理。黑猩猩是易于感染HCV的人，它是唯一的动物，它为研究宿主和病毒的相互作用提供了一个实验模型。在乙型肝炎的发病机理中，与弗兰克·奇萨里（Frank Chisari残留感染细胞的病毒复制和细胞溶解切除。这两种机制是顺序的和重叠的，前者似乎是由干扰素伽玛和后者介导的，而后者是由CD8阳性细胞以及干扰素伽马通过其促炎活性介导的。这些研究还表明，1型干扰素（干扰素α/β）激活的抗病毒蛋白是对病毒感染的响应表达的，但HCV对这种先天免疫反应的抗病毒活性具有抵抗力。对宿主对病毒肝炎免疫反应的微阵列研究以及肝炎病毒如何试图避免反应，产生有关这些疾病发病机理的重要信息，并将研究扩展到其他肝炎病毒中，以扩展到其他宿主中，这些人在不适用的人身上，是偶然的人，是奇异者，是奇异者，是奇异者，这是奇异者，这是奇异者，这是奇异者，这是奇迹，是奇迹，是奇迹，是奇迹，这是奇异者，这是奇异者，这是奇迹，这是奇迹，病毒。黑猩猩中丙型肝炎的其他研究表明，对蛋白质（P7多肽）有些了解对于感染性至关重要，并且包含功能上重要的基因型特异性序列。这一发现为抗丙型肝炎的抗病毒剂开发提供了另一个潜在的靶标。 丙型肝炎。乙型肝炎病毒是一种有缺陷的病毒，需要与乙型肝炎病毒复制。尽管HDV感染并不常见，但它们与严重，快速发展的慢性肝炎有关，导致几年内导致死亡。在一项长期研究慢性丙型肝炎的干扰素α疗法的研究中，观察到了晚期肝硬化的显着消退。尽管传统上认为cirrohsis的逆转是不可能的，但这项研究和其他研究为受影响严重的患者提供了希望，而患者目前唯一的追索是肝移植。 丙型肝炎E.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。