Complete nucleotide sequence and genome organization of Grapevine fleck virus

The complete nucleotide sequence of Grapevine Reck virus (GFkV) genomic RNA was determined. The genome is 7564 nt in size, excluding the 3'-terminal p oly(A) tail, is characterized by an extremely high cytosine content (ca, 50 %), and contains four putative open reading frames and untranslated regions of 291 and 35 nt at the 5' and 3' ends, respectively. ORF 1 potentially en codes a 215.4 kDa polypeptide (p215), which has the conserved motifs of rep lication-associated proteins of positive-strand RNA viruses. ORF 2 encodes a 24.3 kDa polypeptide (p24) identified as the coat protein. ORFs 3 and 4 a re located at the extreme 3' end of the viral genome and encode proline-ric h proteins of 31.4 kDa (p31) and 15.9 kDa (p16), respectively, of unknown f unction, Phylogenetic analysis of the viral replicase and coat protein gene s showed that GFkV is related to members of the Tymovirus and Marafivirus g enera, Two subgenomic RNAs were present in the GFkV preparations as ascerta ined by molecular hybridization, The genome organization of GFkV resembles to some extent that of tymoviruses and marafiviruses. However, differences in the biological and epidemiological behaviour, cytopathology and molecula r properties (i.e. size of genomic RNA and coat protein, and number of ORFs ) support the notion that GFkV is a separate virus belonging in a new genus .