Replication of duck hepatitis B virus in two differentiated human hepatoma cell lines after transfection with cloned viral DNA.

Cloned DNA of duck hepatitis B virus (DHBV) was used to transfect two differentiated human hepatoma cell lines, Huh 7 and Hep G2. Use of the transfected genome as a transcriptional template was demonstrated by the appearance of virus-specific subgenomic and genomic transcripts. Comparison of the steady-state ratio of subgenomic to genomic transcripts in Huh 7 and Hep G2 cells suggests that there are differences in the relative stability and/or rate of production of these transcripts between these cell lines. Viral genomic replication proceeded in both lines, as judged by the presence of DHBV DNA replicative intermediates in cytoplasmic core particles; the levels of these replicative intermediates is roughly equivalent in Huh 7 and Hep G2 cells. Subcutaneous injection of tissue culture medium from transfected Huh 7 cells into Pekin ducks resulted in productive DHBV infection, indicating the production and export of biologically active virus. These cell lines should provide a valuable system for studying the molecular mechanisms of the hepadnaviral life cycle.