In Vitro Reconstitution of -Dependent Duck Hepatitis B Virus Replication Initiation

In vitro systems, providing a defined and controllable chemical environment, have been instrumental in understanding the replication properties of many viruses. A classic example is simian virus 40 (SV40), which, in conjunction with its T antigen, uses host-encoded DNA polymerase for copying its DNA genome (1 ). At the other end, many virus-encoded DNA and RNA polymerases, including retroviral reverse transcriptases (RTs), have been expressed in heterologous systems; when provided with a template nucleic acid and dNTPs or rNTPs, respectively, most exert easily detectable polymerase activity. Achieving the same for the RT (P protein) of hepatitis B virus (HBV) has turned out to be a very difficult, though highly desirable, goal, given the importance of P protein as the only viral enzyme and hence only enzymatic target for therapy.