DAO 74:107-111 (2007)  -  doi:10.3354/dao074107

Antibody response of brown trout Salmo trutta injected with pathogenic Saprolegnia parasitica antigenic extracts

J. M. Fregeneda-Grandes, F. Rodríguez-Cadenas, M. T. Carbajal-González, J. M. Aller-Gancedo*

Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad de León, 24071 León, Spain
*Corresponding author. Email:

ABSTRACT: Brown trout Salmo trutta injected with antigenic extracts from a pathogenic isolate of Saprolegnia parasitica developed specific antibodies that were detected by enzyme-linked immunosorbent assay (ELISA), immunofluorescence (IF) and Western blotting (WB), but not by immunodiffusion (ID). Three groups of five 2 yr old brown trout were injected intraperitoneally with 3 different antigenic extracts: small hyphal fragments (HF) and soluble extracts from sonicated mycelia grown in medium with or without β-sytosterol (SEB and SE, respectively). In the 2 groups injected with SE and SEB, antibodies were found in 66.7% of the serum samples by ELISA, 54.5% by IF and 48.5% by WB. In the group injected with HF, only 1 trout survived the experiment, and in this fish only 1 sample was positive by ELISA. The results obtained by ELISA and IF were similar and show that there is cross-reaction between the antigens used. By WB, the proteins most frequently recognised were 2 proteins of 25 and 29 kDa. No significant differences were found in the groups injected with SE or SEB.

KEY WORDS: Saprolegnia parasitica · Brown trout · Antibody response · Immunological techniques

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