title: A transcriptional map of visna virus: definition of the second intron structure suggests a rev-like gene product.
abstract: Visna virus is the prototype lentivirus, with a genome structure similar to that of the human immunodeficiency viruses HIV-1 and HIV-2. We have analysed in vitro the transcription pattern of this virus in lytic infections of choroid plexus cells. Northern blot analysis shows the presence of spliced subgenomic mRNA species of 4.9, 4.3, 4.0, 1.7 and 1.4 kb. Use of appropriate subgenomic probes shows that the first three of these species encode envelope protein (but also potentially the small open reading frames Q and S). The 1.7 kb RNA could contain S. In order to elucidate the translational coding potential of the smallest RNA, and to characterize further all the transcripts, S1 mapping was performed across those parts of the genome which were close to exon/intron boundaries. This allowed the definition of acceptor splice sites following both introns 1 and 2 as well as donor sites preceding intron 2. The data suggest that the 1.4 kb RNA encodes a protein derived from the F reading frame that may form part of a precursor protein and also contains sequences with some degree of homology to the rev (trs/art) protein of HIV, as well as a typical protease cleavage site between these sequences and the F protein.
authors.affiliation: Department of Veterinary Pathology, University of Edinburgh, U.K.
authors.forename: D R
authors.initials: DR
authors.lastname: Sargan
authors.forename: I D
authors.initials: ID
authors.lastname: Bennet
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D004720:Endonucleases; D005814:Genes, Viral; D007438:Introns; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009710:Nucleotide Mapping; D012326:RNA Splicing; D012333:RNA, Messenger / Q000302:isolation & purification; D012367:RNA, Viral / Q000302:isolation & purification; D015719:Single-Strand Specific DNA and RNA Endonucleases; D014790:Visna-maedi virus / Q000235:genetics*
chemical_list: D012333:RNA, Messenger; D012367:RNA, Viral; D004720:Endonucleases; D015719:Single-Strand Specific DNA and RNA Endonucleases