Visna virus encodes a post-transcriptional regulator of viral structural gene expression

L. S. Tiley, P. H. Brown, Le Shu-Yun Le, J. V. Maizel, J. E. Clements, B. R. Cullen

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


Visna virus is an ungulate lentivirus that is distantly related to the primate lentiviruses, including human immunodeficiency virus type 1 (HIV-1). Replication of HIV-1 and of other complex primate retroviruses, including human T-cell leukemia virus type I (HTLV-I), requires the expression in trans of a virally encoded post-transcriptional activator of viral structural gene expression termed Rev (HIV-1) or Rex (HTLV-I). We demonstrate that the previously defined L open reading frame of visna virus encodes a protein, here termed Rev-V, that is required for the cytoplasmic expression of the incompletely spliced RNA that encodes the viral envelope protein. Transactivation by Rev-V was shown to require a cis-acting target sequence that coincides with a predicted RNA secondary structure located within the visna virus env gene. However, Rev-V was unable to function by using the structurally similar RNA target sequences previously defined for Rev or Rex and, therefore, displays a distinct sequence specificity. Remarkably, substitution of this visna virus target sequence in place of the HIV-1 Rev response element permitted the Rev-V protein to efficiently rescue the expression of HIV-1 structural proteins, including Gag, from a Rev- proviral clone. These results suggest that the post-transcriptional regulation of viral structural gene expression may be a characteristic feature of complex retroviruses.

Original languageEnglish (US)
Pages (from-to)7497-7501
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number19
StatePublished - 1990
Externally publishedYes


  • RNA protein binding
  • retrovirus gene regulation
  • viral latency

ASJC Scopus subject areas

  • General


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