The immune response to Brucella abortus 45/20 adjuvant vaccine in terms of immunoglobin class.

Cattle vaccinated with Brucella abortus 45/20 adjuvant vaccine developed agglutinins for rough brucella antigens which were largely of the IgG classes. Only small amounts of IgM rough agglutinins were produced at the earliest stages of the serological response. Non-agglutinating antibodies detectable in the antiglobulin test were mainly of IgG2 and IgGI classes. Cattle previously exposed to smooth brucella antigens, after vaccination with 45/20 adjuvant vaccine, initially developed high titres of IgM agglutinins reacting with smooth brucella antigens. Subsequently the agglutinins were largely of IgG type. The non-agglutinating antibodies reacting with both smooth and rough antigens were largely of the IgG2 and IgGI sub-classes.