Strawberry vein banding virus isolates in eastern Canada are molecularly divergent from other isolates

The complete sequence of a strawberry vein banding virus (SVBV) isolate collected in Nova Scotia, Canada, and designated NS8, was determined. The 7,856-nucleotide circular double-stranded DNA genome contains seven open-reading frames (ORFs), which is consistent with other SVBV isolates and other members of the genus Caulimovirus. Comparison of NS8 with other whole-genome sequences retrieved from databases revealed that NS8 shares the highest sequence similarity (96.5% identity) with isolate China (accession number HE681085) and the lowest (88.3% identity) with clone pSVBV-E3 (accession number X97304). Despite the overall high sequence similarity between NS8 and China, the coat protein encoding ORF IV of NS8 shares only 90.9% sequence identity with the China isolate. Phylogenetic analysis at the complete-genome level placed NS8 and all Chinese isolates in one clade and clone pSVBV-E3 in a separate clade. Interestingly, phylogenetic analysis of all available ORF IV sequences, including those retrieved from databases and newly sequenced samples in this study from Canada, revealed three distinct clades. All Canadian isolates grouped together as one clade, pSVBV-E3 and several others from Europe, Egypt and the USA grouped as a second clade, and isolates from China formed a third clade. These results demonstrate that SVBV is more divergent than previously reported.