|Abstract or Summary
- Unfertilized ova from spring chinook salmon (Oncorhynchus
tshawytscha) were examined for the presence of classical salmonid
inmmunoglobulin. Immunodiffusion techniques in which rabbit anti-salmonid
immunoglobulin was reacted against an ova homogenate
and rabbit anti-ova homogenate was reacted against immune chinook
serum failed to detect classical-type antibodies within these eggs.
A lectin with bactericidal properties was isolated from spring
chinook salmon ova. This protein agglutinated human type B and
rabbit erythrocytes, but not human type A, O or sheep red cells.
Hemagglutination was inhibited by D-galactose and L-rhamnose.
The protein was purified by affinity chromatography and by gel filtration
on Bio-Rad P300. The purified lectin contained a minor (0. 8 %)
carbohydrate moiety. A rabbit antiserum was prepared against the
protein and used to determine whether ova from coho salmon
(O. kisutch), pink salmon (O. gorbuscha), chum salmon (O. keta), kokanee salmon (O. nerka), steelhead trout (Salmo gairdneri),
Lahonten cutthroat trout (S. clarki henshawi) or fall chinook salmon
(O. tshawytscha) contained a similar protein. All species tested had
an immunologically identical protein within their ova.
Purified spring chinook salmon ova lectin was bactericidal for
two serotypes of Vibrio anguillarum, Pasteurella piscidida,
Aeromonas hydrophila and Flexibacter columnaris, but not for
Yersinia ruckeri, A. salmonicida, Edwardsiella tarda, Cytophaga
psychrophila or the agent of bacterial kidney disease, Corynebacterium
sp. In addition to these known bacterial fish pathogens, 19
species of bacteria commonly associated with humans were tested;
none of the human-associated agents were inhibited by the lectin.
Proteins immunologically identical to the spring chinook salmon
ova lectin were purified froim ova of seven other salmonids and found
to possess little, if any, activity against the bacterial fish pathogens.
Even the protein purified from fall chinook salmon ova had minimal
Less than 1. 0 μg /ml of the purified spring chinook ova lectin
was required for complete inhibition of V. anguillarum growth. A
1 hr incubation of the lectin with the bacteria at 22 C was sufficient
for 100% growth inhibition. Microscopic examination of the incubation
mixture showed that after 20 min, approximately 50% of the
bacteria were no longer motile. No cell lysis was observed. The bacterial inhibition property was stable after heat treatment
at 80 C for 6 hr or 100 C for 1 hr. Lyophilization of the protein
did not reduce bactericidal activity.
The chinook lectin was compared with a plant lectin, ricin,
for bactericidal activity and competitive binding of V. anguillarum
cells. Although ricin had a carbohydrate specificity similar to the
chinook protein, it was not toxic for V. anguillarum; however, it did
compete for binding sites on the bacterium.
Coho salmon which received 125 μg of purified spring chinook
ova lectin intravenously were not protected against subsequent challenge
by V. anguillarum.