Potato rough dwarf virus and Potato virus P are two distinct strains of the same virus species
Two putative members of the genus Carlavirus have been reported infecting potatoes in South America (see EPPO RS 1999/027): Potato rough dwarf virus (in Argentina) and Potato virus P (in Brazil). Studies have recently been done to characterize those two viruses using nucleotide sequence analysis, serology and bioassays. They strongly suggest that Potato rough dwarf virus and Potato virus P are two distinct strains of the same virus species which belongs to the genus Carlavirus.
Sources
Nisbet C, Butzonitch I, Colavita M, Daniels J, Martin J, Burns R, George E, Akhond MAY, Mulholland V, Jeffries CJ (2006) Characterization of Potato rough dwarf virus and Potato virus P: distinct strains of the same viral species in the genus Carlavirus. Plant Pathology 55(6), 803-812.