PRIMARY AND SECONDARY ANTIBODY RESPONSES OF CHICKENS TO PASTEURELLA TULARENSIS
FORT DETRICK FREDERICK MD
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The antibody responses of chickens to killed or viable Pasteurella tularensis were determined. Three preparations were employed viable organisms of the live vaccine strain LVS, viable cells of strain SCHU S4 highly virulent for most laboratory animals but not for chickens, or killed strain SCHU S4. Primary responses were initiated by the intravenous administration of 10 to the ninth power live or killed organisms. Secondary responses were induced by revaccination of each animal with the same preparation 28 days after the vaccine was first administered. Antibody was measured by bacterial agglutination, passive hemagglutination, and agar-gel precipitin techniques. All three methods provided data indicating that the viable SCHU S4 vaccine was superior to either the viable LVS vaccine or the killed SCHU S4 preparation. During the primary response highest levels of antibody were observed on the 12th day following vaccination titers declined rapidly thereafter. Revaccination induced an anamnestic response only when viable LVS or killed SCHU S 4 vaccines were employed. In no case did the secondary response to any of the three vaccines exceed appreciably the primary response to the viable SCHU S4 vaccine.