Hepatitis B virus X protein transactivates the long terminal repeats of human immunodeficiency virus types 1 and 2

Massimo Levrero, Clara Balsano, Gioacchino Natoli, Maria Laura Avantaggiati, Emile Elfassi

Research output: Contribution to journalArticle


The X gene product of the hepatitis B virus (HBV) has been expressed transiently in HepG2 cells, and the 17-kilodalton protein has been detected by Western (immuno-) blot analysis. Cotransfection of the X gene with the long terminal repeat of human immunodeficiency virus type 1 or 2 results in a stimulation of long terminal repeat-directed expression that is higher than the X-induced stimulation of the HBV enhancer linked to either autologous promoter or to the heterologous simian virus 40 promoter. A frameshift mutation abolished this transactivation. In vitro nuclear transcription assays revealed that HBV X acts at the transcriptional level. The carboxy terminus of the HBV X protein does not seem to be necessary for its transactivating activity, as demonstrated by using HBV X protein deletion mutants.

Original languageEnglish
Pages (from-to)3082-3086
Number of pages5
JournalJournal of Virology
Issue number6
Publication statusPublished - 1990


ASJC Scopus subject areas

  • Immunology

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