Detection of plum pox potyvirus using monoclonal antibodies to structural and non-structural proteins.
Eleven monoclonal antibodies specific to plum pox potyvirus (PPV) coat protein were obtained by hybridoma technology from Spanish PPV isolates. In addition, 2 monoclonal antibodies specific to PPV cylindrical inclusions (CIP non-structural proteins) were obtained. The monoclonal antibodies specific for PPV coat protein were assayed by DASI ELISA against 81 PPV isolates. At least 9 different epitopes were found and 21 distinct serological patterns of reaction (serogroups) were established using 9 selected monoclonal antibodies against the collection of PPV isolates, indicating a high variability of coat protein among PPV isolates. Changes in epitope composition were observed after aphid and mechanical transmission, indicating the occurrence of mixtures of isolates in field trees. Monoclonal antibody 5B reacted with all PPV isolates assayed, with very high affinity, using DASI ELISA. This method was compared with immunocapture-PCR on field samples in spring, and showed very good coincidence of results. It is suggested that the efficiency of PPV detection can be slightly increased by using monoclonal antibodies specific to cylindrical inclusions mixed with monoclonal antibodies against structural proteins, and using mixtures of monoclonal antibodies against different epitopes of coat protein. ELISA-I and immunoprinting-ELISA were able to detect CIP and PPV in extracts and tissue section, respectively, of woody plants. Two monoclonal antibodies offer the possibility of distinguishing between Marcus and Dideron PPV types (M or D). It is concluded that these D-specific monoclonal antibodies can be used in routine tests with high affinity. This paper was presented at the EPPO conference on plum pox, held in Bordeaux, France, 5-8 Oct., 1993.