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Furunculosisis a severe, profit limiting disease affecting a wide variety of commercially reared fish species throughout the world. The etiologic agent, Aeromonas salmonicida, produces several potential virulence factors and has some interesting biochemical characteristics that make it a difficult organism to produce an effective vaccine against. A vaccine was prepared using an auto aggregating highly virulent strain of A. salmonicida. This strain was grown by continuous culture fermentation, centrifuged, washed and treated with 5 mM EDTA at an elevated pH. This preparation was used to vaccinate fish.Rainbow and brook trout and Atlantic salmon were immunized by injection or immersion with and without a hyperosmotic infiltration treatment. A dose related response was noted when the bacterin was injected. In juvenile brook trout, at a 1:5 dilution, 44% died due to A. salmonicida infection after challenge; at a 1:10 dilution, 67% died whereas 97% of the control, sham vaccinated fish died. Protection by immersion without a hyperosmotic infiltration treatment was variable with the greatest degree of protection occurring in fish immersed twice. In a typical experiment, mortalities among vaccinated fish ranged from 36.7% for fish immunized once at a 1:10 dilution to 0% for fish immunized twice at 1:10 dilutions two weeks apart. Control mortality was 70%. In fish immunized by immersion in a 1:5 diluted suspension of this bacterin and a concurrent 5% NaCl hyperosmotic treatment , substantial protection was apparent. In a typical experiment mortalities ranged from 7.4% to 22.2% for the vaccinates with control mortalities of 72.7%. It is apparent from this work that successful immersion immunization for the prevention of furunculosis is possible.

Hydrolysis of 2-chloroethyl palmitate and 2-chloroethyl linoleate was studied in artificial gastric juice, artificial pancreatic juice, pig liver homogenates and pig intestine homogenates. Hydrolytic activity was followed by gas-liquid chromatography. Substantial hydrolysis was observed in all preparations except the artificial gastric juice. Hydrolysis constants ranged from <0.001 min−1 in the gastric juice to 0.064 min−1 for the linoleate ester in the pancreatic juice.

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