Metagenomic analysis reveals the presence of prunus virus I in diseased Clematis vitalba: first record of this virus in Italy

Prunus virus I (PrVI) was detected for the first time in Clematis vitalba in Italy using high-throughput sequencing and the complete genome of this isolate, named Clv-1, was assembled and characterized. The results of the bioinformatic analyses were further validated with RT-PCR assays using PrVI-specific primers and Sanger dideoxy sequencing. The Clv-1 genome included three RNA segments of nucleotide lengths of 3468 (RNA1), 2892 (RNA2) and 2225 (RNA3), with five predicted open reading frames. Phylogenetic analyses showed close relationships with other PrVI isolates from different geographical origins, including European and non-European countries. This new pathogen record extends the information on the geographical distribution of PrVI, and possibly reflects the international movement of infected clematis germplasm due to global trade. Further surveys on the presence and distribution of PrVI in weeds and crops, such as the two PrVI hosts sweet cherry and peach, are required in the countries where PrVI has been detected.