Infection initiated by the RNA pregenome of a DNA virus.

We describe experiments demonstrating that after transfection into permissive cells, the RNA pregenome of an avian hepadnavirus, the duck hepatitis B virus, is infectious. Using a Sindbis virus expression vector, we showed that cytoplasmic synthesis of the pregenome resulted in hepadnaviral DNA synthesis. Moreover, complete infectious virus was produced from cells transfected with hepadnaviral pregenomic RNA. We conclude that the pregenome of hepadnaviruses can express all the proteins required for DNA synthesis as well as serve as a template for reverse transcription and that DNA resulting from pregenome expression can be utilized to establish a productive infection in pregenome-transfected cells.