Optimisation of serological detection (ELISA) of the quarantine bacterium Pseudomonas syringae pv. pisi, using IgY-type antibodies from chicken egg yolk and selection of a pea cultivar for biotest.
Four ELISA variants were examined for their sensitivity in detecting P. syringae pv. pisi in propagation material of peas, an alternative to rabbit serum for antibody production was investigated, a suitable indicator plant was selected, and tests on inactivation of the bacterium were made. Direct double antibody sandwich ELISA gave the lowest detection limits: 5 × 104 cells/ml 1:5 diluted sprout sap and 9 × 105 cells/ml 1:5 diluted seed sap. Use of IgY-type antibodies directed against the pathogen and raised in chicken egg yolk gave detection limits comparable with those obtained with IgG-type antibodies from rabbit serum. IgY gave no cross reactions with 13 heterologous bacterial pathogens and there were fewer problems with antigen-unspecific adsorption with IgY than with IgG. The yield of IgY was 20 times greater than that of IgG in the same period. Of 3 pea cultivars tested, Konservenkönigin showed typical symptoms earlier (9 d) after inoculation than did the others, and was therefore considered best suited as an indicator plant. Total inactivation of the pathogen was achieved by heat treatment (50-100°C), microwave treatment and by several chemical disinfectants.