Hypervariable genes in Grapevine leafroll associated virus 1.
Analysis of nucleotide sequences of 10 open reading frames from the Grapevine leafroll associated virus 1 (GLRaV-1), a tentative member of the genus Closterovirus, revealed the presence of an unusually high degree of sequence variation in ORFs 3, 6 and 7 encoding a homologue of heat shock protein 70 and two diverged copies of the coat protein (CPd1 and CPd2), respectively. Overall, 75 clones corresponding to ORFs 3, 6 and 7 were sequenced and 1916 nucleotide changes were recorded relative to the published sequence. Surprisingly, none of the changes resulted in a frame shift or stop codon and there was a trend for the conservation of amino acids or change to amino acids having similar physiochemical properties. The CPd2 gene was particularly variable with a mutation seen in 60% of the nucleotide positions in one or more of the 1.1-kb cDNA clones sequenced. These observations suggest that GLRaV-1 may exist in the form of a heterogeneous population, possibly resulting from the lack of selective pressure and from mixing of virus strains due to viticulture practices of vegetative propagation and grafting over the centuries.
Little
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CSIRO Plant Industry and Cooperative Research Centre for Viticulture, Adelaide Laboratory, P.O. Box 350, SA 5064, Glen Osmond, Australia.
Fazeli
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CF
Rezaian
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MA
D002213:Capsid / Q000235:genetics; D017790:Closterovirus / Q000235:genetics*; D003062:Codon; D014644:Genetic Variation; D016679:Genome, Viral; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D016366:Open Reading Frames; D017423:Sequence Analysis, RNA
D003062:Codon; D018840:HSP70 Heat-Shock Proteins