Immune response in bulls vaccinated with Brucella abortus strain RB51

The objective of this research was to determine the effect of vaccinating adult bulls with Brucella abortus strain RB51 on body fluid and cellular response. Twenty mixed blooded Zebu bulls with an average age of 3 years were selected in the South Maracaibo Lake region, Zulia state, Venezuela. The animals were divided into two groups. Group 1 (n=10) received a simple dosis of 10,000,000,000 UFC of RB51 in a 2mL subcutaneous injection and the other group (n=10) was not vaccinated. The bulls were sampled every 15 days in a serological diagnosis with traditional brucellosis tests (Rosa de Bengala. Aglutination on slides and in test tubes, 2-Mercaptoethanol and competitive Elisa). After 70 days of vaccination the animals were sampled to measure the cellular response with the lymphoblastic transformation test with different antigens of the RB51 strain. No antibody response was observed in any of the traditional serological diagnostic tests and the vaccinated animals showed significantly higher levels of cellular immune response (P<0.05) than the non-vaccinated animals, especially in relation to the 18Kda antigen of RB51. For this reason it can be concluded that the use of Brucella Abortus strain RB51 at a dose level of 10 billion UFC/mL, does not induce the formation of antibodies that interfere with the serological diagnostic tests for brucellosis infection and does produce a good cell protection response.