CHARACTERIZATION OF APHANOMYCES-INVADANS BY ELECTROPHORETIC AND WESTERN-BLOT-ANALYSIS

Fungal mycelium extracts were subjected to gel electrophoresis and Wes tern blot analysis with various lectins and polyclonal antisera. These techniques succeeded in identifying bands specific to pathogenic Apha nomyces strains from fish affected by epizootic ulcerative syndrome, r edspot disease and mycotic granulomatosis when compared to various oth er Oomycete fungi. It is concluded that these isolates are conspecific under the name Aphanomyces invadans [previously described by Willough by et al. 1995 (J Fish Dis 18:273-275) as A. invaderis] and the variou s protein and carbohydrate bands identified may provide useful species -specific taxonomic markers. Besides the distinctive band profiles for A. invadans on gels subjected to various stains, lectins revealed a s pecific 45 kDa component, and polyclonal antisera highlighted an immun ogenic 10 kDa band. Peroxidase and fluorescein conjugated antisera pro vided an effective diagnostic tool for identifying hyphae in infected fish tissue.