Liver diseases associated with hepadnavirus infection. A study in duck model

Among four hepadnaviruses, we studied liver diseases of duck hepatitis B virus (HBV)-infected animals. There was close correlation of viral infection and development of liver diseases. The presence of hepatocellular carcinoma (HCC) was observed in Chinese ducks. We previously showed that duck HBV DNA was integrated in the neoplastic cells. Analysis of duck HBV integrants revealed the similarity to the reported structures of HBV integrants. To develop effective antiviral therapy, we tested adenine arabinoside (Ara-A), phosphonoformate, azido-deoxythymidine (AZT), and dideoxycytidine (DDC) in this in vivo model. Significant suppressive effects on viral replication were observed by phosphonoformate and adenine arabinoside, but AZT and DDC failed to show significant antiviral effects. This may be related to a unique pathway of replication in hepadnaviruses.