title: Hepatitis B virus X gene can transactivate heterologous viral sequences.
abstract: The smallest open reading frame of hepatitis B virus (HBV) has been designated the X gene and its biological function during HBV infection and replication is not known. Experiments described here demonstrate that expression of the HBV X gene in HepG2 cells containing a plasmid with the chloramphenicol acetyltransferase (CAT) gene under control of the human immunodeficiency virus (HIV-1) long terminal repeat (LTR) sequence leads to a marked increase in CAT gene transcription as well as expression of the gene product (CAT). The HIV-1 tatIII gene and the HBV X gene together increased HIV-1 LTR-regulated CAT expression above that observed with either gene alone, suggesting a synergistic effect of the X gene and tat. HBV X gene also stimulated expression of the CAT gene under control of the simian virus 40 enhancer and early promoter but not the visna virus LTR or the human T-cell lymphotropic virus type I (HTLV-I) LTR, indicating that the HBV X gene can transactivate some but not other heterologous viral sequences. Transactivation of the HIV-1 LTR by the HBV X gene varied in different cell lines, suggesting that it may be mediated by a cellular factor(s).
authors.affiliation: Division of Infectious Diseases, Stanford University School of Medicine, CA 94305-5107.
authors.forename: J S
authors.initials: JS
authors.lastname: Twu
authors.forename: W S
authors.initials: WS
authors.lastname: Robinson
mesh_terms: D002460:Cell Line; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D004274:DNA, Recombinant; D003907:Dexamethasone / Q000494:pharmacology; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation / Q000187:drug effects; D005814:Genes, Viral; D006678:HIV / Q000235:genetics; D006515:Hepatitis B virus / Q000235:genetics*; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D013539:Simian virus 40 / Q000235:genetics; D013045:Species Specificity; D014158:Transcription, Genetic; D014162:Transfection; D014790:Visna-maedi virus / Q000235:genetics
chemical_list: D004274:DNA, Recombinant; D003907:Dexamethasone; D015500:Chloramphenicol O-Acetyltransferase