Bacillus toyonensis BCT-7112T transient supplementation improves vaccine efficacy in ewes vaccinated against Clostridium perfringens epsilon toxin.

AIM The aim of the present study was to examine the vaccine immune response in ewes supplemented with Bacillus toyonensis BCT-7112T during a period of 5-day supplementation before vaccination against a recombinant Clostridium perfringens epsilon toxin (rETX). METHODS AND RESULTS Ewes were vaccinated with 200 µg of rETX adjuvanted with 10% aluminum hydroxide. The treat group was orally supplemented with B. toyonensis BCT-7112T (3 × 108 viable spores) for 5 days prior to the first and second vaccination. Ewes supplemented with B. toyonensis BCT-7112T showed higher neutralizing antibody titers than the non-supplemented ewes (P < 0.05), with an increase in serum levels for total IgG anti-rETX by 3.2-fold (P < 0.0001), and for both IgG isotypes IgG1 and IgG2 by 2.1-fold and 2.3-fold (P < 0.01), respectively, compared with the control group. The peripheral blood mononuclear cells of ewes in the supplemented group had a higher (P < 0.05) cytokine mRNA transcription levels for IL-2 (6.4-fold increase), IFN-γ (2.9- fold increase) and transcription factor Bcl6 (2.3-fold increase) compared with the control group. CONCLUSION We conclude that a 5 days of supplementation with B. toyonensis BCT-7112T prior vaccination is sufficient to significantly improve the humoral immune response of ewes against C. perfringens recombinant ETX vaccine. SIGNIFICANCE AND IMPACT OF STUDY These findings open a new perspective in the utilization of B. toyonensis BCT-7112T as an immunomodulator since a 5 days period of probiotic supplementation is sufficient to improve the vaccine immune response.