Presence of a recombinant isolate of Plum pox virus in Apulia

During spring 2003, a small focus of infection by Plum pox virus (PPV) that involved four trees was discovercd in an apricot orchard in the Province of Brindisi (Apulia, southern Italy). Virus isolates from all these trees were serologically typed by DASI-ELISA using four strain-specific monoclonal antibodies (Mabs). One isolate (PPV-BR) was also characterized by RFLP analysis of PCR products derived from two genome regions, i.e. coat protein (CP) and P3-6K1. PPV-BR proved to be a recombinant as it typed as PPV-M by strain-specific MaDs and RFLP analysis of the CP gene, but as PPVD by analysis of the P3-6K1, gene. Sequence analysis of the (Cter)NIb-(Nter)CP region of this recombinant showed that the recombination breakpoint was located in the C terminus of the NIb gene, as has been reported for other recognized PPV recombinants. This represents the first record of a recombinant isolate of PPV from Italy.