HEPATITIS DELTA VIRUS-RNA, PROTEIN-SYNTHESIS AND ASSOCIATED CYTOTOXICITY IN A STABLY TRANSFECTED CELL-LINE

A trimer of hepatitis delta virus (HDV) cDNA in a retrovirus expression vector was transfected into a subclone of the PLC/PRF/5 human hepatoma cell line, and a stable cell line (H1δ9) was clonally selected that supported the synthesis of both genomic and antigenomic sense HDV RNA. The H1δ9 cell line also expressed hepatitis delta antigen (HDAg) in cell nuclei in three distinct morphological patterns, including patterns typically seen in HDV-infected livers. HDAg expression was restricted to the smaller (p24) of the two HDAg-associated polypeptides in early passages of the H1δ9 cell line, but continuous passage of the cells resulted in increasing expression of the larger (p27) HDAg-specific polypeptide. Passage of the H1δ9 cells also led to sustained expression of monomeric HDV RNA and a reduction in the levels of dimeric- and trimeric-HDV RNA. This was accompanied by an attenuation of virus-related cytotoxicity which was a feature of early cell passage numbers. HDV RNA replication in these cells was resistant to actinomycin D suggesting that replication was not dependent on continued expression from the transfected HDV cDNA and thus was likely to be self-sustaining. © 1990.