P. 107-111Brown 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.S
