Structure and biological activity of the subgenomic Mtv-6 endogenous provirus

Kiho Cho, David A. Ferrick, David W. Morris

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


The Mtv-6 provirus has an incomplete genome, but retains a functional superantigen gene (sag) which directs the thymicdeletion of CD4+ T cells expressing T cell receptors containing the Vβ3 or Vβ5 chains. To better understand the Mtv-6 superantigen, the structure and biological activity of the Mtv-6 provirus was analyzed. First, the complete nucleotide sequence was determined, and the mutation producing the subgenomic provirus was identified. Second, the nucleotide sequence of the 5′ end of the sag gene transcript (including the splice junction) was determined by sequence analysis of a cDNA clone. Third, the superantigen activity of Mtv-6 was analyzed in mice carrying the Mtv-6 provirus isolated by selective breeding on a genetic background free of endogenous and exogenous mouse mammary tumor virus (MMTV). These studies demonstrate that (i) the Mtv-6 provirus contains a 6.2-kb deletion between two 12-bp direct repeats encompassing the central portion of the provirus but not affecting sag gene splicing or translation, (ii) the sag gene transcript has the structure predicted from previous S1 nuclease mapping studies, and (iii) the Mtv-6 superantigen can direct thymic deletion of target Vβ3+ and Vβ5+T cells in the absence of gene products from full-length MMTV proviruses.

Original languageEnglish (US)
Pages (from-to)395-402
Number of pages8
Issue number1
StatePublished - Jan 10 1995

ASJC Scopus subject areas

  • Virology
  • Infectious Diseases


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