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 delta virus antigen in the replication of hepatitis delta virus RNA, we have transfected a stable HDAg-positive cell line (A3) and the parental HDAg-negative line (HepG2) with HDV RNA produced in 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 microgram/ml alpha-amanatin providing firm evidence that, like viroids, this function is performed by host RNA polymerase II.
MacNaughton
T B
TB
Division of Medical Virology, Institute of Medical and Veterinary Science Frome Road, Adelaide, South Australia.
Gowans
E J
EJ
McNamara
S P
SP
Burrell
C J
CJ
D000546:Amanitins / Q000494:pharmacology; D000956:Antigens, Viral / Q000378:metabolism*; D006528:Carcinoma, Hepatocellular; D002460:Cell Line; D002472:Cell Transformation, Viral; D003698:Hepatitis Delta Virus / Q000235:genetics* / Q000502:physiology; D035923:Hepatitis delta Antigens; D006801:Humans; D008113:Liver Neoplasms; D012319:RNA Polymerase II / Q000378:metabolism; D012367:RNA, Viral / Q000235:genetics*; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection
D000546:Amanitins; D000956:Antigens, Viral; D035923:Hepatitis delta Antigens; D012367:RNA, Viral; C442244:hepatitis delta virus large antigen; D012319:RNA Polymerase II