REGULATION OF HEPATITIS B VIRAL GENE EXPRESSION

阐明病毒基因的分子调控 表达可能导致新的抗病毒治疗方式。通过 基因和生化分析，我们的实验室已经证明 乙肝病毒中存在一种新的基因元件(HRL) 对病毒基因的高效表达至关重要的基因组 产品。这种遗传因素正顺式作用于 转录后水平，其功能在转录后水平上发挥 作为转录序列一部分的RNA处理。类似于 HIV-1的REV-RRE相互作用的功能，该元件似乎 抑制剪接过程，促进运输和 乙肝病毒转录本的利用。这一HRL元素还可以起到 乙肝病毒致病机制和宿主反应的重要作用 感染。我们还在研究监管效果 宿主衍生的因子对这一元件的作用。在乙肝病毒中 转基因小鼠模型，肿瘤坏死因子-α和干扰素-γ已被 在转录后水平上抑制乙肝病毒基因的表达 这可能与HRL元素有关。一直以来 提示该作用不是直接作用于肝细胞。 而是通过旁分泌机制治疗肝脏非实质性病变 细胞。Kupffer细胞与肝癌细胞共培养体系的建立 表达乙肝表面抗原，我们证明了加入肿瘤坏死因子-α 干扰素-γ对HBs-Ag表达有明显的抑制作用。 这种作用不是由肿瘤坏死因子-α的直接作用所介导的，而且 干扰素-γ对肝癌细胞的影响。很可能这两个人 细胞因子激活库普弗细胞产生一种因子(S)，在 反过来，抑制乙肝病毒基因的表达。正在进行研究，以 确定并进一步表征这一分子机制 效果。

Elucidating the molecular regulation of viral gene expression may lead to new modalities of antiviral therapy. By genetic and biochemical analyses, our laboratory has demonstrated the existence of a novel genetic element (HRL) within the HBV genome that is important for efficient expression of viral gene products. This genetic element is cis-acting at the posttranscriptional level, and its function is exerted at the level of RNA processing as part of transcribed sequences. Similar to the function of Rev-RRE interaction of HIV-1, this element appears to inhibit the splicing process and facilitate the transport and utilization of HBV transcripts. This HRL element may also play an important role in the pathogenesis and host response of HBV infection. We are also studying the regulatory effects of host-derived factors on the function of this element. In the HBV transgenic mouse model, TNF-alpha and IFN-gamma have been shown to inhibit HBV gene expression at a posttranscriptional level that is presumably related to the HRL element. It has been suggested that the effect is not directly exerted on the hepatocytes but rather via a paracrine mechanism on hepatic nonparenchymal cells. Using a co-culture system of Kupffer cells and hepatoma cells expressing HBsAg, we demonstrated that addition of TNF-alpha and IFN-gamma induced a strong inhibition of HBsAg expression. This effect is not mediated by a direct effect of TNF-alpha and IFN-gamma on the hepatoma cells. It is likely that these two cytokines activated the Kupffer cells to produce a factor (s) that, in turn, inhibited HBV gene expression. Studies are under way to identify and further characterize the molecular mechanism of this effect.