Transfer of hepatitis B virus genome by adenovirus vectors into cultured cells and mice: Crossing the species barrier

For the study of hepatitis B virus infection, no permissive cell line or sm all animal is available. Stably transfected cell lines and transgenic mice which contain hepadnavirus genomes produce virus, but-unlike in natural inf ection-from an integrated viral transcription template. To transfer hepadna virus genomes across the species barrier, we developed adenovirus vectors i n which 1.3-fold-overlength human and duck hepatitis B virus genomes were i nserted. The adenovirus-mediated genome transfer efficiently initiated hepa dnavirus replication from an extrachromosomal template in established cell lines, in primary hepatocytes from various species, and in the Livers of mi ce. Following the transfer, hepatitis B virus proteins, genomic RNA, and al l replicative DNA intermediates were detected. Detection of covalently clos ed circular DNA in hepatoma cell lines and in primary hepatocytes indicated that an intracellular replication cycle independent from the transferred l inear viral genome was established. High-titer hepatitis B virions were rel eased into the culture medium of hepatoma cells and the various primary hep atocytes. In addition, infectious virions were secreted into the sera of mi ce. In conclusion, adenovirus-mediated genome transfer initiated efficient hepatitis B virus replication in cultured liver cells and in the experiment al animals from an extrachromosomal template. This will allow development o f small-animal systems of hepatitis B virus infection and will facilitate s tudy of pathogenicity of wild-type and mutant viruses as well as of virus-h ost interaction and new therapeutic approaches.