This project was initiated in an attempt to control furunculosis
(Aeromonas salmonicida) in a production hatchery rearing coho salmon.
An oral vaccine was prepared and administered to 520,000
juvenile coho salmon (Oncorhynchus kisutch) at the Siletz River Salmon
Hatchery prior to the onset of a predictable naturally occurring
epizootic of furunculosis. A group of 65,000 salmon served as a
The Fermacell Fermentor was used to grow the Aeromonas
salmonicida cells. The cell yield was more than doubled with the
addition of 175 grams of dextrose to the culture media accompanied
by automatic control of the pH. The cells were subjected to ultrasonic
disruption and the supernatant fluid was precipitated with alum.
The resulting material was lyophilized and incorporated into the Oregon
Moist Pellet diet at a concentration of 201.73 milligrams ± 3
milligrams per kilogram of pellets.
Immunization with vaccine-containing food was begun on March
26, 1967 with 14 consecutive days of initial vaccination followed by
eight weekly boosters. It was calculated that each fish could receive
approximately 360.7 micrograms of vaccine during the immunization
During the period of May 1 through July 12, 1967, all hatchery
mortalities were collected and examined for the presence of Aeromonas
salmonicida. Although the nonimmunized control group
showed a higher total loss and a higher furunculosis loss than the
immunized groups, the results fail to indicate any distinctive difference
between these two lots. The lower mortalities observed in the
immunized group may indicate that slight immunity had been induced
by the vaccine. However, any low-level immunity which may have
been produced was not sufficient to provide protection against infection
by Aeromonas salmonicida.
The number of mortalities appeared to be closely associated
with the hatchery water temperature. An increase in water temperature
was accompanied by a corresponding increase in losses. A decline
in losses appeared to be associated with a decrease in water
Of the fish examined, 146 animals showed the presence of an
acid-fast organism tentatively identified as Mycobacterium fortuitum (Cruz).
Agglutinating antibody titers on serum samples from the immunized
and nonimmunized groups of fish failed to indicate any
meaningful difference between these groups.
Repository Record Id:
Fryer, J. L.
Oregon State University. Graduate School
Oral immunization for possible control of furunculosis in fish