STUDIES ON THE REPLICATION AND ONCOGENICITY OF HBV

据估计，有1.76亿慢性乙肝病毒携带者 (乙肝病毒)世界范围内与携带者有关的强有力的附属学证据 与肝细胞癌的发展状况。因此，它是最重要的 拥有可用于病毒研究的体外系统的重要性 复制和阐明乙肝病毒感染机制(S) 细胞变得恶性转化。尽管已经有可能 通过转染啮齿动物细胞获得病毒功能的部分表达 对于克隆的HBVDNA，这些细胞不支持有效的病毒复制 它们也不会变得恶毒。然而，克隆的HBVDNA 能够引起黑猩猩的肝炎。的工作假说 这里提出的实验是相对较弱的启动子 与表面编码基因以外的乙肝病毒基因相关 病毒抗原不能克服宿主和/或组织特异性 由啮齿动物细胞或非肝脏来源的细胞施加的限制。因此， 为了实现我们建立体外研究系统的长期目标 乙肝病毒，我们建议：1)在小鼠体内获得高表达的病毒基因 已经携带整合的乙肝病毒基因的品系，通过a)用 已知可增强整合病毒基因组表达的化合物；b) 让他们接触到肿瘤促进剂和亚有效剂量的物理和 化学致癌物和c)通过用额外的 再循环的乙肝病毒基因组或使用新的杂交质粒，其中病毒 基因组与强启动子或增强序列相连；2)发展 设计用于在猿猴细胞中进行异体复制或给予 在培养的肝细胞中高效表达病毒功能；3) 引入再循环建立携带乙肝病毒序列的转基因小鼠 乙肝病毒基因组或带有与强连锁的乙肝病毒序列的杂交质粒 启动子导入小鼠胚胎细胞；4)建立原位检测方法 适合与活组织检查材料一起使用的杂交技术 慢性乙型肝炎不同临床分期与乙肝病毒基因表达的关系 肝病。这些研究应该至少阐明一些因素。 在转基因小鼠的培养细胞中调节乙肝病毒基因的表达 以及在感染者的肝脏中。

There are an estimated 176 million chronic carriers of hepatitis B virus (HBV) world wide and strong epidiomological evidence linking the carrier state with development of hepatocellular carcinoma. Thus, it is of utmost importance to have in vitro systems available for studying viral replication and for elucidating the mechanism(s) by which HBV infected cells become malignantly transformed. Although it has been possible to obtain partial expression of viral functions by transfecting rodent cells with cloned HBV DNA, these cells do not support efficient viral replication nor do they become malignantly transformed. Nevertheless, cloned HBV DNA is capable of causing hepatitis in chimpanzees. The working hypothesis for the experiments proposed here is that the relatively weak promoters associated with HBV genes other than the gene coding for the surface antigen of the virus cannot overcome host and/or tissue specific restrictions imposed by rodent cells or cells of non-hepatic origin. Thus, to meet our long-term goal of establishing in vitro systems for studying HBV, we propose 1) to obtain increased expression of viral genes in mouse lines that already carry integrated HBV genes by a) treating them with compounds known to enhance expression of integrated viral genomes; b) exposing them to tumor promoters and subeffective doses of physical and chemical carcinogens and c) by "superinfecting" them with additional recircularized HBV genomes or with new hybrid plasmids in which the viral genome is linked to strong promoters or enhancing sequences; 2) to develop hybrid plasmids designed to replicate episomally in simian cells or to give efficient expression of viral functions in cultured hepatocytes; 3) to create transgenic mice carrying HBV sequences by introducing recircularized HBV genomes or hybrid plasmids with HBV sequences linked to strong promoters into mouse embryo cells; 4) to develop methods of in situ hybridization suitable for use with biopsy material which will allow association of HBV gene expression with various clinical stages of chronic liver disease. These studies should elucidate at least some of the factors that regulate expression of HBV genes in cultured cells, in transgenic mice and in the liver of infected individuals.