Efeito imunomodulador de Bacillus cereus var Toyoi e Saccharomyces boulardii em animais vacinados contra Herpesvírus Bovino tipo 5

Abstract

The immunization of livestock as a means to control infectious diseases began more than a century ago. It has however aroused new interest in view of new demands by consumer markets, restricting the use of antibiotics and other chemotherapeutical drugs. In addition, more effective vaccines, with fewer side effects, have been developed through the use of adjuvants and purified antigens. Probiotics modulate the immune response, enhancing the effect of vaccines, which opens up a new perspective on their possible uses. Bacillus cereus var. Toyoi and Saccharomyces boulardii are resistant to environmental conditions, which facilitate their use in the production, conservation and management of animal feed. The objective of the present study was to evaluate the immunomodulatory effects of Bacillus cereus var. Toyoi and Saccharomyces boulardii on the immune response of animals both during and after the interruption of its administration. Two experiments were conducted, one with mice and the other with sheep. In each experiment, the animals were divided into three groups, one supplemented with B. cereus var. Toyoi, another with S. boulardii and the third was the control group, i.e., without supplementation. As experimental model we used an inactivated vaccine against BoHV-5. Seroconversion and neutralization were used to evaluate the humoral immune response and cytokine expression in splenocytes and peripheral leukocytes, so as to evaluate the cellular response. All of the groups showed increased levels of antibodies due to vaccination. The calves fed probiotics had higher antibody levels than the control group both during supplementation and after its suspension. In the supplemented animals a change was observed in the profile of the immune response in Th1 as compared to Th2. This effect was observed through the data represented by the cytokine profile, as well as through the IgG isotype. Each probiotic had a distinct profile of cytokines, suggesting that the B. cereus var. Toyoi and S. boulardii mediated immunomodulation have distinct mechanisms of action. These data suggest that the use of B. cereus var. Toyoi and S. boulardii probiotics are effective modulators of vaccine response, and are a viable alternative for increasing the efficiency of commercial vaccines.