Immunoglobulin class specificity of non-agglutinating antibody produced in cattle following Brucella abortus 45/20 vaccination.

The immunoglobulin class specificity of non-agglutinating antibody produced following vaccination with Br. abortus 45/20 vaccine was determined using the antiglobulin test. In previously unvaccinated cattle it was found that most of the non-agglutinating antibody was associated with the IgG1 immunoglobulin class. In cattle sensitised to Brucella antigens by prior vaccination with Brucella abortus strain 19 the majority of antibody was also associated with the IgG1 immunoglobulin class, but a significant amount of IgG2 antibody was also present. The results indicate that the significance of levels of IgG2 antibody would be difficult to determine in cattle repeatedly exposed to Brucella antigens.