DEFECTIVE INTERFERENCE OF HEPADNAVIRUS IN NATURE

我们的长期目标是了解与病毒性肝炎和肝癌相关的病理生物学。乙型肝炎病毒（HBV）是人类第四大最常见的传染性病原体。慢性HBV感染与肝癌的发生密切相关。虽然热免疫和病毒因素都被认为有助于慢性感染的建立，但HBV慢性感染的机制仍有待充分探索。在许多细菌、植物和动物的RNA和DNA病毒中发现了缺陷干扰颗粒，并且已知与组织培养中的持续感染有关。然而，自von Magnus（1947）在实验室环境中首次在流感病毒中发现DI颗粒以来，尚未在人类自然感染中证实其存在。使用一种新的方法，我们提供了人类慢性HBV携带者中di样病毒存在的第一个实验证据。这些自然发生的HBV“核心故意缺失变体”（CID）的功能表征揭示了DI颗粒的所有特征。在本应用中，我们建议研究CID变异在患者和土拨鼠动物模型中的生物学意义。我们将研究人类患者中HBV CID变异滴度波动的现象。此外，我们建议研究最近发现的土拨鼠肝炎病毒（WHV）核心内部缺失变异（论文提交）在组织培养中是否也表现得像DI颗粒。最后，我们将通过遗传和生化方法继续研究HBV CID变异的缺陷干扰机制。将区分“阻遏因子样模型”和“优先复制”模型。这项工作的成功完成将对导致高度恶性肝癌发展的慢性病毒性肝炎具有重要意义。

Our long-term goal is to understand the pathobiology associated with viral hepatitis and liver cancer. Hepatitis B virus (HBV) is the 4th most common infectious agent in humans. Chronic infection with HBV is tightly associated with the development of liver cancer. Although both hot immune and viral factors are believed to contribute to the establishment of chronic infection, the mechanism of HBV chronic infection remains to be fully explored. Defective interfering (DI) particles have been found in many RNA and DNA viruses of bacteria, plants, and animals, and are known to be associated with persistent infection in tissue culture. However, the existence of DI particles has not yet been demonstrated in human natural infections since their first discovery in influenza virus by von Magnus (1947) in the laboratory setting. Using a new approach, we provided the first experimental evidence for the existence of DI-like viruses in human chronic HBV carriers. Functional characterization of these naturally-occurring "core intentional deletion variants" (CID) of HBV reveals all of the characteristic features of DI particles. In this application, we propose to study the biological significance of CID variants in patients and woodchuck animal model. We will investigate the phenomenon of fluctuating titers of HBV CID variants in human patients. In addition, we propose to investigate if woodchuck hepatitis virus (WHV) core internal deletion variants, which we have found recently (manuscript submitted) also behave like DI particles in tissue culture. Finally, we will continue our studies of the mechanism of defective interference of HBV CID variants by both genetic and biochemical approaches. A "repressor-like model" versus a "preferential replication" model will be distinguished. Successful completion of this work will have important implications for chronic viral hepatitis which leads to the development of highly malignant liver cancer.