A preliminary study of the development of 19S and 7S immunoglobulins in sera of two sheep vaccinated with Brucella abortus, strain 19.

The pattern of antibody response to vaccination with Brucella abortus, strain 19, was studied in two sheep. Agglutinative activity was detected by the third and fifth days and complement - fixing activity by the fifth and seventh days post-vaccination. Density gradient centrifugation and DEAE cellulose column chromatography showed the 19S antibody developed first, followed soon after by 7S antibody. The former had disappeared by the 25th day but the latter persisted longer in both sheep. A small amount of 19S antibody was detected in sheep 1 following a booster dose of vaccine but 7S antibody constituted the major secondary response. The standard tube agglutination test was found to be more efficient than the complement-fixation test for titration of 19S antibody. An increase in the salt concentration to 10% in tube agglutination test rendered it more sensitive in demonstrating 7S antibody.