Addison William R, Walters Kathie-Anne, Wong Winnie W S, Wilson John S, Madej Danuta, Jewell Lawrence D, Tyrrell D Lorne J
Department of Medical Microbiology and Immunology and Glaxo Wellcome Research Centre, University of Alberta, Edmonton, Alberta, Canada.
J Virol. 2002 Jun;76(12):6356-63. doi: 10.1128/jvi.76.12.6356-6363.2002.
Covalently closed circular DNA (cccDNA) is a crucial intermediate in the replication of hepadnaviruses. We inhibited the replication of duck hepatitis B virus in congenitally infected ducks with a combination of lamivudine and a dideoxyguanosine prodrug. Inhibition of viral replication should prevent renewal of the cccDNA pool, and its decay was measured in liver biopsy samples collected over a 5-month period. In three ducks, the cccDNA pools declined exponentially, with half-lives ranging from 35 to 57 days. In two others, the pools declined exponentially for about 70 days but then stabilized at about 6 copies/diploid genome. The selection of drug-resistant virus mutants is an unlikely explanation for this unexpected stabilization of cccDNA levels. Liver sections stained for the cell division marker PCNA showed that animals in which cccDNA loss was continuous had significantly greater numbers of PCNA-positive nuclei than did those animals in which cccDNA levels had plateaued.
共价闭合环状DNA（cccDNA）是嗜肝DNA病毒复制过程中的关键中间体。我们使用拉米夫定和一种双脱氧鸟苷前药的组合抑制先天性感染鸭体内鸭乙型肝炎病毒的复制。抑制病毒复制应可防止cccDNA库的更新，我们在5个月期间收集的肝活检样本中对其衰减情况进行了测定。在三只鸭中，cccDNA库呈指数下降，半衰期为35至57天。在另外两只鸭中，cccDNA库在约70天内呈指数下降，但随后稳定在约6拷贝/二倍体基因组水平。耐药病毒突变体的选择不太可能解释cccDNA水平这种意外的稳定情况。对细胞分裂标记物增殖细胞核抗原（PCNA）进行染色的肝脏切片显示，cccDNA持续丢失的动物中PCNA阳性细胞核的数量显著多于cccDNA水平已趋于平稳的动物。
