Characterization, nucleotide sequence and genome organization of leek white stripe virus, a putative new species of the genus Necrovirus
Résumé
White stripe is a disease affecting leek in France with which an isometric virusc. 30 nm in diameter is associated. The most evident symptom is the presence of white stripes on the leaves extending to the stem. Attempts to demonstrate transmission through the soil by sowing or transplanting leek in contaminated soil were unsuccessful. The virus was transmitted by sap inoculation to a narrow range of herbaceous hosts, all of which were infected only locally. Virus purification was from infected leek tissues, where it accumulated in large amounts, as demonstrated by ultrastructural observations. RNA was extracted from purified virus preparations and cDNA clones were prepared. The complete nucleotide sequence of the viral RNA was determined: The genome is 3662 nucleotides long and contains five open reading frames (ORFs). The first (ORF 1) encodes a putative translation product of Mr 23803 (p24) and read through of its amber stop codon results in a protein of Mr 82625 (p83) (ORF 2). ORF 3 and ORF 4 encode two small polypeptides of Mr 11280 (p11) and Mr 6261 (p6), respectively. ORF 5 encodes the capsid protein of Mr 27460 (p27). The genome organization and sequence alignments with the corresponding products of necroviruses suggest that the virus isolated from leek is a new species in the genusNecrovirus, for which the name of leek white stripe virus (LWSV) is proposed.