Studies on the Mechanism of Infection and Replication of Hepatitis B Virus

1984年，我们建立了一种可以被乙型肝炎病毒（HBV） DNA转染并允许这种病毒复制的细胞系。从那时起，人们对这种病毒进行了许多分子生物学研究，但对DNA聚合酶（pol）的产生以及病毒核酸被包装成核的机制却一无所知。这两个问题我们已经调查过了。我们询问HBV pol是否如病毒基因组结构所提示的那样是作为核心-pol融合多肽合成的。为此，构建了一个不能启动核心蛋白，但能合成pol蛋白的突变基因组，并将其用于转染研究。结果表明，在没有核心蛋白合成的情况下产生了pol活性，证明了核心-pol融合蛋白的产生不是pol产生的先决条件。为了深入了解HBV基因组核酸包装成核心颗粒的过程，构建了几个缺失衍生物来观察包装能力。结果表明，HBV基因组携带一个独特的序列，可识别无包装信号。该序列长度不超过75个核苷酸。

In 1984 we have established a cell line that can be transfected by hepatitisB virus (HBV) DNA, and allows replication of this virus. Since then, many molecular biological studies with this virus have been done, but nothing has been understood as to the DNA polymerace (pol) production, and the mechanism where by viral nucleic acid is packaged into core. We have investigated into these two problems.1. We asked whether HBV pol is synthesized as a core-pol fusion poly-peptide, as suggested from the viral genome structure. For this purpose, a mutant genome that cannot initiate core protein, but can synthesize pol protein was constructed and used for transfection studies. The results showed that pol activity was made in the absence of core protein synthesis, proving that production of core-pol fusion protein is not a prerequisite for pol production.2. To obtain insights into packaging process of HBV genome nucleic acid into core particles, several deletion derivatives were constructed to see packaging ability. The results showed that the HBV genome carries a unique sequence to be recognized no packaging signal. This sequence was found not more than 75 nucleotide long.