Leaky transcription termination produces larger and smaller than genome size hepatitis B virus X gene transcripts

Virology. 1991 Apr;181(2):630-6. doi: 10.1016/0042-6822(91)90896-j.


The genomic DNA of hepatitis B virus (HBV) is circular and has only one known transcription termination site. The HBV X protein coding sequence is flanked by this transcription termination site at the 3' end and a promoter element at the 5' end. Transcription initiating from the X promoter and terminating at the termination site would produce a transcript 0.7 kb in length, which we have detected in cell lines that produce HBV particles. Unexpectedly, a 3.9-kb transcript containing two copies of the X gene sequence was also detected in these cell lines. Polymerase chain reaction analysis indicates that this 3.9-kb transcript contains sequences from both upstream and downstream of the termination site. Thus, transcription of this 3.9-kb transcript initiates from the X promoter, reads through the termination site, and terminates the second time it encounters the site. Analysis using an SV40-derived vector indicates that the transcription termination site in the HBV genome is also leaky for X gene transcription when a heterologous promoter initiates the transcription. Based on these results, the mechanism of how the transcription termination of HBV mRNA is regulated is discussed.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Base Sequence
  • Binding Sites
  • Blotting, Northern
  • Cell Line
  • Genes, Viral*
  • Hepatitis B virus / genetics*
  • Molecular Sequence Data
  • Polymerase Chain Reaction
  • Promoter Regions, Genetic
  • RNA, Messenger / metabolism
  • Trans-Activators / genetics*
  • Transcription, Genetic*


  • RNA, Messenger
  • Trans-Activators
  • hepatitis B virus X protein