The hepadnaviral reverse transcriptase can synthesize DNA on its native RNA template within viral cores but it is usually unable to synthesize DNA employing exogenous nucleic acids as a template. The mechanism of this template commitment is unknown. Here we provide evidence that the RNAseH activity of duck hepatitis B virus reverse transcriptase may also be unable to act on exogenous substrates.
Department of Molecular Microbiology and Immunology, St Louis University School of Medicine, 1402 South Grand Blvd, St Louis, MO 63104, USA. gongyh@viridae.com