Partial sequence analysis of an atypical Turkish isolate provides further information on the evolutionary history of...

A variety of techniques, such as typing with subgroup-specific monoclonal antibodies, restriction length polymorphism (RFLP) analysis or subgroup-specific RT-PCR are available for the discrimination of Plum pox virus (PPV) isolates. However, the existence of PPV isolates showing abnormal typing properties has been observed in the past [Candresse, T., Cambra, M., Dallot, S., Lanneau, M., Asensio, M., Gorris, M.T., Revers, F., Macquaire, G., Olmos, A., Boscia, D., Quiot J.B., Dunez, J., 1998. Comparison of monoclonal antibodies and polymerase chain reaction assays for the typing of isolates belonging to the D and M serotypes of Plum pox potyvirus. Phytopathology 88, 198-204.]. In an effort to understand the molecular mechanisms underlying such anomalous serological and molecular typing characteristics, partial 3' (1449 nt) and 5' (3706 nt) sequences have been determined for an atypical Turkish PPV isolate (Abricotier Turquie or Ab-Tk). The results obtained indicate that its unusual typing behaviour is caused by point mutations affecting key restriction sites and epitopes and confirm that this isolate represents a divergent member of the PPV-M subgroup. In addition, analysis of the partial Ab-Tk genomic sequences demonstrated that the 5' region of the genome of this isolate has a mosaic structure resulting from recombination event(s), shedding new light on the evolutionary history of Plum pox virus.