Trans-activation of viral enhancers by the hepatitis B virus X protein

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Abstract

We have used the chloramphenicol acetyltransferase (cat) gene expression system to study the effect of the X protein of hepatitis B virus (HBV) on viral enhancers. Plasmids containing the HBV enhancer and the core gene promoter linked to the cat gene were cotransfected with a plasmid containing the X gene into the human hepatoma cell line PLC/PRF/5. Our results indicate that the transfected X gene caused a trans-activation of the HBV enhancer. If a frameshift mutation or a deletion in the X structural gene was created, this trans-activation function was abolished. This result and the observation that the frameshift mutation did not alter the transcription of X mRNA suggest that the X protein is the trans-activating factor. Using similar techniques, we found that the X protein was also capable of trans-activating the simian virus 40 (SV40) and Rous sarcoma virus enhancers (pSV2cat and pRSVcat) in CV-1 cells. However, trans-activation of the SV40 enhancer by the X protein was not observed in COS-1 cells. By cotransfecting pSV2cat and the X gene with a plasmid containing either the intact SV40 genome, the SV40 genome devoid of the T-antigen (T-ag) gene, or only the T-ag gene, we demonstrated that SV40 T-ag can suppress trans-activation by the X protein. SV40 T-ag did not inhibit expression of the X gene or inactivate the X protein. The most probable mechanism of this inhibition is that T-ag competes with the X protein for a common target.

Original languageEnglish
Pages (from-to)427-434
Number of pages8
JournalJournal of Virology
Volume62
Issue number2
StatePublished - 1988

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Hepatitis B virus
Simian virus 40
transcriptional activation
Viral Tumor Antigens
Genes
antigens
genes
proteins
chloramphenicol acetyltransferase
frameshift mutation
plasmids
Frameshift Mutation
Proteins
Chloramphenicol O-Acetyltransferase
Plasmids
Genome
Rous sarcoma virus
Gene Expression
genome
hepatitis B virus X protein

ASJC Scopus subject areas

  • Immunology

Cite this

Trans-activation of viral enhancers by the hepatitis B virus X protein. / Spandau, Dan; Lee, Chao-Hung.

In: Journal of Virology, Vol. 62, No. 2, 1988, p. 427-434.

Research output: Contribution to journalArticle

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