Howe A Y, Robins M J, Wilson J S, Tyrrell D L
Glaxo Heritage Research Institute, University of Alberta, Edmonton, Canada.
Hepatology. 1996 Jan;23(1):87-96. doi: 10.1002/hep.510230113.
Hepatitis B virus (HBV) replication is mediated by the viral polymerase that possesses three functional domains: primer, DNA polymerase/reverse transcriptase, and RNase H. Using the Pekin duck as an animal model, we demonstrate a novel mechanism of inhibition of duck hepatitis B virus (DHBV) by 2,6-diaminopurine 2',3'-dideoxyriboside (ddDAPR), a prodrug of 2',3'-dideoxyguanosine (ddG). A selective and irreversible inhibition of DHBV DNA replication is found in ducklings treated with high doses of ddDAPR (20 to 50 mg/kg), but not with similar doses of 2',3'-dideoxycytidine (ddC). The inhibition mediated by ddDAPR occurs at a very early stage of the reverse transcription. Despite the inhibition of DHBV DNA replication by ddDAPR, the DNA polymerase and reverse transcriptase activities of the polymerase are found to remain active when tested on exogenous templates in activity gels. We have demonstrated direct binding of [alpha-32P]ddGTP to the DHBV polymerase expressed in an in vitro transcription and translation system. These results suggest that the binding of ddGTP to the polymerase blocks the initial DNA replication.
乙型肝炎病毒（HBV）的复制由具有三个功能结构域的病毒聚合酶介导：引物、DNA聚合酶/逆转录酶和核糖核酸酶H。我们以北京鸭作为动物模型，证明了2,6 - 二氨基嘌呤2',3'-二脱氧核糖核苷（ddDAPR，2',3'-二脱氧鸟苷（ddG）的前体药物）抑制鸭乙型肝炎病毒（DHBV）的一种新机制。在用高剂量ddDAPR（20至50mg/kg）处理的雏鸭中发现了对DHBV DNA复制的选择性和不可逆抑制，但用相似剂量的2',3'-二脱氧胞苷（ddC）处理则未出现这种情况。ddDAPR介导的抑制发生在逆转录的非常早期阶段。尽管ddDAPR抑制了DHBV DNA复制，但在活性凝胶中对外源模板进行测试时，发现该聚合酶的DNA聚合酶和逆转录酶活性仍然活跃。我们已经证明了[α-32P]ddGTP与在体外转录和翻译系统中表达的DHBV聚合酶的直接结合。这些结果表明，ddGTP与聚合酶的结合阻断了初始DNA复制。
