Sequence analysis of the 5' untranslated region of swine vesicular disease virus reveals block deletions between the end of the internal ribosomal entry site and the initiation codon.
Swine vesicular disease virus (SVDV) is a picornavirus closely related to the human pathogen coxsackievirus B5. In common with other picornaviruses, the 5' untranslated region (5' UTR) of SVDV contains an internal ribosomal entry site (IRES) that plays an important role in cap-independent translation. The aim of this study was to use RT-PCR and sequencing to characterize a fragment of the 5' UTR encompassing the entire IRES. Sequence analysis demonstrated high nucleotide identities within the IRES between 33 representative SVDV isolates. These data support the choice of this region as a diagnostic target and provide information for the improvement of laboratory-based molecular assays to detect SVDV. In contrast to the relative conservation of the IRES element, there was considerable nucleotide variability in the spacer region located between the cryptic AUG at the 3' end of the IRES and the initiation codon of the polyprotein. Interestingly, 11 SVDV isolates had block deletions of between 6 and 125 nt in this region. Nine of these isolates were of recent European origin and were phylogenetically closely related. In vitro growth studies showed that selected isolates with these deletions had a significantly reduced plaque diameter and grew to a significantly lower titre relative to an isolate with a full-length 5' UTR. Further work is required to define the significance of these deletions and to assess whether they impact on the pathogenesis of SVD.
Shaw
Andrew E
AE
Institute for Animal Health, Ash Road, Pirbright, Surrey GU24 0NF, UK.
Reid
Scott M
SM
Institute for Animal Health, Ash Road, Pirbright, Surrey GU24 0NF, UK.
Knowles
Nick J
NJ
Institute for Animal Health, Ash Road, Pirbright, Surrey GU24 0NF, UK.
Hutchings
Geoffrey H
GH
Institute for Animal Health, Ash Road, Pirbright, Surrey GU24 0NF, UK.
Wilsden
Ginette
G
Institute for Animal Health, Ash Road, Pirbright, Surrey GU24 0NF, UK.
Brocchi
Emiliana
E
Department of Research, Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, Via Bianchi 7/9, 25124 Brescia, Italy.
Paton
David
D
Institute for Animal Health, Ash Road, Pirbright, Surrey GU24 0NF, UK.
King
Donald P
DP
Institute for Animal Health, Ash Road, Pirbright, Surrey GU24 0NF, UK.
D020121:5' Untranslated Regions / Q000235:genetics*; D018387:Codon, Initiator / Q000235:genetics; D029822:Enterovirus B, Human / Q000235:genetics*; D017353:Gene Deletion; D016679:Genome, Viral; D009690:Nucleic Acid Conformation; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism*; D017421:Sequence Analysis; D017384:Sequence Deletion
D020121:5' Untranslated Regions; D018387:Codon, Initiator