Humoral and cellular immune response to Brucella abortus strain RB51 vaccine in grazing heifers supplemented with selenium and α-tocopherol

Abstract

In order to evaluate the effect of selenium and α-tocopherol supplementation on the immune response to Brucella abortus strain RB51, four groups of six grazing heifers were used. Three months before the start of the trial, the groups Se-T and Se were supplemented in single dose with barium selenate (1 mg selenium/kg body weigth) and groups Se-T and T were supplemented with 500 IU α-tocopherol/100 kg each two months. Group C was maintained without supplementation. Once established differences in metabolic balance groups, the trial began with the RB51 vaccine administration. Blood samples with heparin and without additive were obtained from each cow for the determining blood activity of glutathione peroxidase (GPx) and plasma concentration of cholesterol and α-tocopherol. The humoral immune response was evaluated by ELISA and the cellular immune response by an intradermal test antigen of B. abortus. Differences between groups were evaluated by tests repeated measures ANOVA, paired samples t and Kruskal-Wallis. It was considered significant when the P value was less than 0.05. Supplementation with selenium and α-tocopherol established differences between groups (P < 0.05). The humoral immune response and cellular response to RB51 vaccine was lower in group T (P < 0.05). It is possible to conclude that humoral and cellular immune response to the vaccine RB51 can be negatively modulated by plasma α-tocopherol concentration at the immunization.