Efeito imunomodulador do Bacillus toyonensis em equinos imunizados com vacinas clostridiais recombinantes

Abstract

Probiotic microorganisms can stimulate the immune response, enhancing vaccine efficiency. Bacillus toyonensis is a non-pathogenic, Gram-positive bacterium that has been used as a probiotic in animal supplementation. Supplementation with B.toyonensis induces immunomodulatory effects, increasing vaccine response indifferent species. This study evaluated the effect of supplementation with B. toyonensis on the modulation of the immune response in horses vaccinated with recombinant vaccines against toxins from Clostridium tetani and Clostridium haemolyticum. For this purpose, horses were divided into 2 groups: group 1, animals were orally supplemented for a period of 42 days with viable spores of B. toyonensis (1x108), starting 7 days before the primary vaccination; group 2 received only the placebo (40ml), the control group. Serum samples were collected to evaluate the humoral immune response using an indirect ELISA, and whole blood samples with sodium citrate were collected for cytokine transcription evaluation (qPCR) by cell proliferation in peripheral blood cells. Results: Total IgG levels were 3 times higher (p<0.05) on day35 in the supplemented group against the rTeNT antigen, compared to the control group. Specific anti-rTCHB antibody levels were approximately 2 times higher (p<0.05) than controls at all points studied. In titration, the non-supplemented group obtained specific IgGs up to a dilution of 1:400, while the supplemented group reached 1:3200 anti- rTeNT, and the control group reached up to 1:400, while the supplemented group reached 1:800 anti-rTCHB. The supplemented group showed higher levels of IgGa on day 42 and IgGT on days 35 and 42 anti-rTeNT, and IgGa and IgGT at significantly higher levels (p<0.05) (~1.5 times) than controls, with no influence on IgGb anti-rTCHB. In relative cytokine expression, the supplemented group, when stimulated with the probiotic, showed approximately 15 IL1, 8.5 TNF-α, 7 IL10, and 6.5 IL4. In relative cytokine expression, the supplemented group, when stimulated with rTCHB, the relative expression of IL1 and TNFα cytokines was similar in both groups, however, IL10 was approximately 13 times higher in the supplemented group, and IL4 transcription was not detected. Conclusion: Horses supplemented with B. toyonensis obtained higher antibody levels against rTeNT and rTCHB. Supplementation provided a mixed Th1 and Th2 cellular and humoral response.