Treatment of hepatitis B virus without inducing antiviral resistant viruses and analyses of HBV integration at an early stage of infection before development of hepatocellular carcinoma.

1.拉米夫定是一种核苷类似物，最近被用于治疗HBV感染。然而，据报道，长期给予该药物导致出现耐药病毒，其在病毒DNA聚合酶的酪氨酸-甲硫氨酸-天冬氨酸（YMDD）基序处发生点突变，并加重临床病程。我们已经开发了一种敏感的检测方法，这些突变病毒和分析变异病毒的出现之前和拉米夫定治疗期间，以澄清YMDD突变病毒爆发的机制。我们已经证明，在一些未经拉米夫定治疗的HBV携带者中，YMDD基序突变的变异型HBV已经作为少数存在。然而，这些突变病毒的存在并不总是导致其在拉米夫定治疗期间爆发。这些结果表明，YMDD突变的爆发需要其他选择力或因素，可能是YMDD基序以外的其他区域的突变，宿主对HBV的免疫力受损等。2.越来越多的证据表明，B肝炎病毒（HBV）整合及其导致的插入突变在肝细胞癌（HCC）的细胞生长或维持中起重要作用。我们以前报道过，HBV整合发生在HBV感染早期，甚至在急性自限性肝炎后。因此，插入突变可能代表了肝癌发生前几十年的第一个剧烈的遗传变化。我们的病毒标记方法提供了（a）慢性感染早期肝细胞中HBV整合的有力证据和（B）揭示了可能受HBV整合影响并与肝肿瘤发生相关的细胞基因。与以前的共识相反，我们证明了HBV整合的首选染色体，这意味着一些整合体的选择机制。

1.Lamivudine, a nucleoside analog, is recently used for treatment of HBV infection. However, it is reported that prolonged administration of this drug results in emergence of resistant viruses with point mutations at tyrosine-methionine-aspartate-aspartate (YMDD) motif of viral DNA polymerase and exacerbation of clinical course. We have developed a sensitive assay for these mutant viruses and analyzed emergence of variant viruses before and during lamivudine treatment to clarify mechanisms involved in outbreak of YMDD-mutant viruses. We have demonstrated that variant HBV with mutations at YMDD motif already exists as minority in some HBV carriers without lamivudine treatment. However, existence of these mutant viruses did not always lead to their outbreak during lamivudine treatment. These results imply that outbreak of YMDD mutants needs other selection forces or factors, possibly, mutations in other regions than YMDD motif, impaired host immunity to HBV, and such.2.Growing evidence demonstrates that hepatitis B virus (HBV) integration and resulting insertional mutagenesis play an important role in cell growth or maintenance in hepatocellular carcinomas (HCCs). We previously reported that HBV integration occurs early during HBV infection, even after acute self-limiting hepatitis. Insertional mutagenesis may, therefore, represent the first drastic genetic change preceding the development of HCC by a few decades. Our virus-tagging approach provided (a) firm evidence of HBV integration in hepatocytes at an early stage of chronic infection and (b) revealed cellular genes possibly affected by HBV integration and related to liver tumorigenesis. In contrast to the previous consensus, we demonstrated a preferred chromosome for HBV integration which implies a selection mechanism for some integrants.