ANALYSIS OF 2 ELISA FORMATS AND ANTIGEN PREPARATIONS USING POLYCLONALANTIBODIES AGAINST PHOMOPSIS-LONGICOLLA

Polyclonal antibodies (PAbs) were produced in New Zealand white rabbit s with culture filtrate and mycelial extract immunogen preparations fr om the soybean (Glycine max) fungal pathogen Phomopsis longicolla. The PAbs were purified to the immunoglobin fraction and tested in indirec t enzyme-linked immunosorbent assay (ELISA) and in double antibody san dwich-ELISA (DAS-ELISA). The PAbs raised to culture filtrate were more specific but less active in binding to members of the Diaporthe-Phomo psis complex than were those raised to the mycelial extract immunogen preparation. DAS-ELISA was more specific and 100-fold more sensitive i n detecting members of the complex than was indirect ELISA. Variabilit y in specificity between different PAbs was lower in DAS-ELISA compare d with indirect ELISA. Immunization of one rabbit with culture filtrat e over an extended time resulted in maximum anti-P. longicolla activit y after three immunizations, and the activity became constant against most members of the complex at the same time. Reactivity to some cultu res of P. longicolla was undetectable following the fourth and fifth i mmunizations, whereas reactivity to all of our other cultures of the c omplex remained high.