Plum pox virus capsid protein mobility in SDS-polyacrylamide gel electrophoresis

Slovak plum pox virus (PPV) isolates BOR-3 and KR-4 behaved atypically in polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE) of their capsid proteins (CPs). Whereas other tested PPV isolates could be sorted by SDS-PAGE into groups corresponding to the M or D strains, as controlled by restriction fragment length polymorphism (RFLP) analysis, the two above mentioned isolates behaved as the M strain according to RFLP analysis but not SDS-PAGE. Slight mobility differences were observed also among the isolates belonging to the D strain. SDS-PAGE of the CP thus cannot clearly distinguish between these two main PPV strains. BOR-3 isolate has been shown atypical also in its biological properties, and it reacted very weakly with a monoclonal antibody (MAb) recognizing well both M and D strains in immunoblot analysis.