A. Thuvander et al., HUMORAL ANTIBODY-RESPONSE OF BROWN TROUT SALMO-TRUTTA VACCINATED AGAINST FURUNCULOSIS, Diseases of aquatic organisms, 17(1), 1993, pp. 17-23
Two year old brown trout Salmo trutta L. in a freshwater farm with a h
istory of enzootic Aeromonas salmonicida infections were vaccinated wi
th a commercial vaccine against furunculosis by intraperitoneal inject
ion either with or without a booster. Antibody levels to 3 cellular an
tigen preparations from A. salmonicida, i.e. whole cells of A. salmoni
cida, A-layer protein, and lipopolysaccharide (LPS) isolated from the
bacterium, were measured using an ELISA technique. Antibodies to whole
cell A. salmonicida and LPS were demonstrated in both vaccinated and
non-vaccinated fish. Antibodies to A-layer protein were only detected
in very low quantities in non-vaccinated fish, In vaccinated fish, the
levels of these antibodies were significantly higher in boosted fish
than in fish vaccinated only once. Western blot analyses of fish serum
also revealed antibodies to LPS and A-layer protein. Antibody activit
ies to extracellular products from A. salmonicida were mainly against
a 70 kDa component and LPS. Prior to a challenge test in which furuncu
losis was induced by increasing the water temperature, all fish were b
led and individually marked. Only boosted fish showed significant prot
ection in this challenge, and no mortalities were recorded in this gro
up. The groups of fish which had received only 1 immunization were not
protected against furunculosis. In these groups, pre-challenge antibo
dy levels to cell membrane antigens, as measured by ELISA, did not dif
fer between survivors and non-survivors. This indicates that high leve
ls of specific antibodies to cellular antigens do not correlate with s
urvival of the individual fish.