Molecular characterization of Potato virus V genomes from Europe indicateslimited spatiotemporal strain differentiation

Because there were no previous reports on the molecular characterization of Potato virus V (PVV, genus Potyvirus, family Polyviridae), the complete ge nomic sequence of PVV isolate Dv42 was determined. The length of the single -stranded messenger-polarity RNA genome was 9,851 nt (nucleotides), followe d by a poly(A) tail. The genome contained a 5'-terminal nontranslated regio n (5'-NTR; 204 nt), a single open reading frame (nucleotides 205-9406; 3,06 7 amino acids), and a 3'-NTR that was unusually long (446 nt) compared with that of Potato virus Y (PVY; 331-nt 3'-NTR), Potato virus A (PVA; 207-nt 3 '-NTR), and other potyviruses that naturally infect Solanaceae species. Phy logenetic analysis with the cylindrical inclusion protein-encoding and coat protein (CP)encoding regions indicated that PVV Dv42 was most closely rela ted to Pepper mottle virus and PVY, respectively. Seven PVV isolates (inclu ding Dv42) collected from cultivated potatoes in the Netherlands, the Unite d Kingdom, and Norway from 1964 to 1997 were uniform in serological propert ies and symptomatology in indicator hosts that could distinguish strains of PVY and PVA. The nucleotide sequences of the 5'-NTR., P1, CP, and 3'-NTR r egions of the PVV isolates were determined and were 94.6 to 99.5, 96.3 to 9 8.8, 96.4 to 98.7, and 96.3 to 99.6% identical, respectively. The amino aci d similarities for the P1 and CP were 95.8 to 98.6 and 96.0 to 97.8%, respe ctively. Phylogenetic analysis of the CP sequences of PVY revealed no signi ficant grouping, in contrast to PVY and PVA, which were grouped largely acc ording to the previously recognized strains based on host responses. Howeve r, the relatively few differences in the P1 sequences of PVV were correlate d with the different countries of origin. Hence, the PVV isolates infecting potatoes in Europe seem to vary little genetically and may belong to a sin gle strain.