摘要：A dairy herd with 17% Brucellosis prevalence was vaccinated or re-vaccinated with RB51. Five groups of ten cows each were classified according to their response to serologic tests. Additionally, one group with infected animals and one with animals originating from a Brucellosis free herd were used as positive and negative controls. A Radial Immunodiffusion test (RID) was used to confirm results. Indirect ELISA was carried out with LPS of B. abortus 2308 (LPS-S) or LPS of B. abortus RB51 (LPS-R) as primary antigens and anti-IgG1, IgG2, IgM and IgA as secondary antigens. When LPS-S was used as antigen, vaccinated and re-vaccinated cows that were positive to card and Rivanol tests, showed an IgG1-type response. Animals that were infected mainly showed an IgG2 type response. When LPS-R was used, none of the animals showed a significant response. Immunized cows that had contact with the wild-type strain showed humoral immune response that was detected as positive serology tests. Therefore, in endemic zones confirmation tests such as RID, Rivanol with titers above 1:100, or ELISA with LPS-S as antigen and IgG2, are essential to differentiate between animals vaccinated with RB51, which have a transitory immune response , from those that are infected.
