Characterization of Potato rough dwarf virus and Potato virus P: distinct strains of the same viral species in the genus Carlavirus

• Published in: Plant pathology 2006-12, Vol.55 (6), p.803-812
• Main Authors: Nisbet, C, Butzonitch, I, Colavita, M, Daniels, J, Martin, J, Burns, R, George, E, Akhond, M.A.Y, Mulholland, V, Jeffries, C.J
• Format: Article
• Language: English
• Subjects: amino acid sequences; bioassays; Biological and medical sciences; Carlavirus; coat proteins; Datura metel; disease resistance; Ditta; DNA-binding proteins; Fundamental and applied biological sciences. Psychology; host plants; microbial genetics; molecular sequence data; molecular systematics; Nicandra physalodes; Nicotiana edwardsonii; Nicotiana occidentalis; nucleotide sequence analysis; nucleotide sequences; pathogen identification; Phytopathology. Animal pests. Plant and forest protection; Plant viruses and viroids; Potato rough dwarf virus; Potato virus P; potatoes; PVP specific monoclonal antibody; serodiagnosis; serology; Solanum tuberosum; strain differences; strains; virus‐strains
• ISSN: 0032-0862; 1365-3059
• DOI: 10.1111/j.1365-3059.2006.01448.x

In an attempt to resolve whether two putative carlaviruses, potato rough dwarf virus (PRDV) and potato virus P (PVP), reported infecting potato in Argentina and Brazil, respectively, are the same virus in the genus Carlavirus, they were characterized using nucleotide sequence analysis, serology and bioassay. For PRDV and PVP, sequences of 2016 and 1492 bp, respectively, were obtained. Similarity searches of coat-protein amino acid sequences and the presence of the nucleic-acid-binding protein exhibiting the characteristic motif C-X₂-C-X₁₁-C-X₄-C, highly conserved in carlaviruses, showed PRDV and PVP to be members of the genus Carlavirus. Further analysis showed that they were the same virus species since the full coat-protein sequence, translated from the nucleotide sequence, exceeded the 84% minimum identity required for members of the same species within the genus Carlavirus, at 90·8% identity in an ungapped alignment of 304 amino acids. Moreover, the viruses could not be distinguished using polyclonal antibodies raised to PRDV and PVP in ELISA. They could, however, be distinguished using an anti-PVP monoclonal antibody, which did not react to PRDV, and by differences in the susceptibility of plant species and potato cultivars to infection and/or symptom expression following mechanical inoculation. Host plants Datura metel, Nicandra physalodes and Nicotiana edwardsonii were reliably infected systemically with PVP, but not with PRDV. Although all potato cultivars tested were infected, there were marked differences between cultivars in the symptoms produced. The cultivars Ditta and King Edward showed symptoms (including stunting and mottle) when infected with PRDV, but not when infected with PVP. Based on the results, it is proposed that PRDV is a strain of PVP within the genus Carlavirus. For detection of the viruses in postentry quarantine, it is recommended that PRDV or PVP polyclonal antibodies are used, together with inoculation to Nicotiana occidentalis N. megalosiphon-P1. For differentiation of PRDV and PVP, the PVP monoclonal antibody may be used together with inoculation to D. metel and N. physalodes (systemic infection with PVP but not PRDV, determined using ELISA).