Production of Anti-Bacterial Agglutinins by Carp and Trout at 10° G

In recent years costly losses to the salmon industries and trout hatcheries of middle Europe, Great Britain, and North America have been caused by a generalized bacteremia, the etiological agent of which is Bacterium salmonicida. These losses have raised the question as to the possibility of inducing immunity in brood stocks of these species by the use of bacterial vaccines.

There is no physiological characteristic of fish, amphibians, or reptiles known to the author that indicates that the reaction of these animals to the injection of a bacterial vaccine should differ from the response of the warm blooded vertebrates. Nevertheless, a search of the literature has failed to reveal a single attempt to immunize fish with vaccines. Indeed, there are very few studies reporting the production of any antibodies by cold-blooded animals upon the injection of foreign proteins, and most of these reports concern animals held at 20°C or above.

Five studies report the production of antibodies against red blood cells. Lazar 1 injected frogs with washed bovine erythrocytes and incited the development of agglutinin titers of 1:10 to 1:80 in some individuals. Many animals, however, were negative. Schwarzmann 2 also found that frogs developed hemoagglutinins on the injection of erythrocytes. Allen and McDaniel 3 held 2 groups of frogs at room temperature (22°C to 27°C) and 2 similar groups in the refrigerator (8°C to 10°C). One group at each temperature was injected with human erythrocytes. The only one of the 4 groups that developed hemolysins was the one injected with erythrocytes and held at room temperature. These workers concluded that only when the frogs were kept above 20°C did they develop antibodies. Wollman 4 confirmed these results in experiments which also indicated that temperature is a determining factor as to whether or not frogs will produce antibodies.