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First Report of Grapevine leafroll-associated virus 5 in Spain

Grapevine leafroll-associated viruses (GLRaVs) cause significant reductions in yield and quality in the wine industry worldwide. At least nine different GLRaVs have been found in different regions of the world. In the process of virus indexing of candidate grapevine clones for certification, which includes grafting of scions onto rootstocks, we observed strong leafroll symptoms 1 year after grafting with one vine of cv. Estaladina in Castilla y León, Spain and one vine of cv. Tempranillo in La Rioja, Spain, collected in 2008 and 2007, respectively. Both vines tested positive by real-time reverse transcription (RT)-PCR with TaqMan probes specific for Grapevine leafroll-associated virus 5 and double-antibody sandwich (DAS)-ELISA with a mix of monoclonal antibodies that recognizes GLRaV-4, 5, 6, 7, and 9 (Bioreba, Reinach, Switzerland). RNA extracts of both GLRaV-5 positive vines were analyzed by conventional RT-PCR with a pair of consensus degenerated primers derived from GLRaV-5 hsp70 sequences available in GenBank: LR5HYF (5′-TGGGATGAAYAARTTCAATGC-3′) and LR5HYR (5′-TGAAATTCCTCATRTARGAGC-3′) that amplified a 250-bp fragment. Amplicons were cloned and the comparison of the amino acid sequences (Estaladina isolate, Est110: Accession No. HM208622; Tempranillo isolate, Tem020: Accession No. HM208618) showed in the case of the Est110 isolate, 100 and 82.6% identity, respectively, with the homologous genes of one GLRaV-5 isolate from the United States (AF233934 [3]) and Argentina (EU815935 [2]). For isolate Tem020, the hsp70 gene showed 97.1 and 81.2% amino acid identity with the homologous hsp70 genes of the United States and Argentina isolates. The coat protein (cp) genes of both isolates were also amplified and cloned using the specific GLRaV-5 primers, LR53413 (5′-CGTGATACAAGGTAGGACAACCGT-3′) and LR53843 (5′-CTTGCACTATCGCTGCCGTGAAT-3′), designed according to the sequence of AF233934. Fragments were of the expected size (430 bp) and the nucleotide sequences were obtained (Est110: Accession No. HM363522; Tem020: Accession No. HM363523) and used for pairwise nucleotide comparisons. The Est110 isolate showed 96.7 and 97.5% amino acid identity with the isolates from the United States and Argentina, respectively, while the Tem020 isolate showed 94.8 and 95.6% identity, respectively. Amino acid identity of Est110 and Tem020 cp genes was 100% when compared with the homologous genes of isolates AF233934 and EU815935. To our knowledge this is the first report of GRLaV-5 in Spain. Since 2008, we have detected eight additional vines positive for this virus in 200 clones analyzed for certification, suggesting that the incidence of GLRaV-5 in Spain could be widespread. This research indicates that virus indexing for GLRaV should be included in certification schemes for grapevine candidate clones (1) in Spain.

References: (1) Anonymous. OEPP/EPPO Bull. 38:422, 2008. (2) S. Gomez Talquenca et al. Virus Genes 38:184, 2009. (3) F. Osman et al. J. Virol. Methods 141:22, 2007.