Resposta Imunológica de Bezerras Bubalinas (Bubalus Bubalis) à vacinação com amostra indutora (B19) e não indutora (RB51) de anticorpos aglutinantes

Abstract

Brucellosis is a zoonosis of great sanitary and economic importance that affects several animal species, including the buffalo species (Bubalus bubalis), negatively impacting One Health and herd productivity. This study aimed to evaluate the immune response of buffalo heifers vaccinated with the B19 and RB51 strains against brucellosis in the municipality of Viana, located in the Baixada Maranhense region, State of Maranhão, Brazil. Thirty female buffaloes aged between 3 and 12 months were sampled and randomly divided into three experimental groups of ten animals each: Group 1 (G1), vaccinated with the B19 strain; Group 2 (G2), vaccinated with the RB51 strain; and Group 3 (G3), unvaccinated control group. Blood samples were collected on days 0 (pre-vaccination), 14, 90, and 180 post-vaccination. Biological material collected from groups G1 and G3 was subjected to the Buffered Acidified Antigen (BAA) test and the 2-Mercaptoethanol (2-ME) test to detect the post-vaccination immune response. The results showed that the B19 vaccine induced an immune response with 100% of the animals reacting to the BAA test up to day 90, with a decrease in this response by day 180, when 10% of the group showed no reaction. In the 2-ME test, a gradual decline in IgG titers was observed over time, with detectable responses up to day 180. The control group remained negative throughout all periods. In Group 2 (G2), vaccinated with the RB51 strain, the Agar Gel Immunodiffusion (AGID) test was used to assess the immune response. No reactive animals were detected at any of the sampling times (0, 14, 90, or 180 days). The findings highlight the importance of using diagnostic tests capable of distinguishing vaccinated from non-vaccinated animals to avoid false-positive or false- negative results, as well as the need to develop serological techniques specific for animals vaccinated with non-agglutinating antibody-inducing strains (RB51). Such developments can support vaccination strategies and active surveillance for animal brucellosis, promoting control of this disease in buffaloes in the Baixada Maranhense region.