HEPATITIS-DELTA ANTIGEN IS NECESSARY FOR ACCESS OF HEPATITIS-DELTA VIRUS-RNA TO THE CELL TRANSCRIPTIONAL MACHINERY BUT IS NOT PART OF THE TRANSCRIPTIONAL COMPLEX

To examine the role of hepatitis S virus antigen in the replication of hepatitis δ virus RNA, we have transfected a stable HDAg-positive cell line (A3) and the parental HDAg-negative line (HepG2) with HDV RNA producedin vitro; synthesis of complementary HDV RNA was only detected in HDAg-positive cultures. In contrast, nuclear homogenates from both HDAg-positive and -negative cells synthesized comparable levels of complementary RNA from exogenous HDV RNA. These findings indicate that HDAg is not a necessary component of the transcriptional complex and suggest with other evidence, that a major role for HDAg is likely to be transport of HDV RNA from cytoplasm to nucleus. Transcription of HDV RNA by intact nuclei was sensitive to 1 μ/ml a-amanatin providing firm evidence that, like viroids, this function is performed by host RNA polymerase II. © 1991 Academic Press, Inc.