Immunomodulatory effect of short-term supplementation with Bacillus toyonensis BCT-7112T and Saccharomyces boulardii CNCM I-745 in sheep vaccinated with Clostridium chauvoei.

The bacterium Clostridium chauvoei is the causative agent of blackleg in livestock, and vaccination is the most effective means of prevention. The aim of this study was to assess the effect of short-term supplementation with Bacillus toyonensis and Saccharomyces boulardii on the immune response to a C. chauvoei vaccine in sheep. Sheep were vaccinated subcutaneously on day 0 and received a booster dose on day 21, with 2 mL of a commercial vaccine formulated with inactivated C. chauvoei bacterin adsorbed on aluminum hydroxide. Probiotics were orally administered B. toyonensis (3 × 108 cfu) and S. boulardii (3 × 108 cfu) over five days prior to the first and second doses of the vaccine. Sheep supplemented with B. toyonensis and S. boulardii showed significantly higher specific IgG, IgG1, and IgG2 titers (P<0.05), with approximately 24- and 14-fold increases in total IgG levels, respectively, than the nonsupplemented group. Peripheral blood mononuclear cells from the supplemented group had increased mRNA transcription levels of the IFN-γ, IL2, and Bcl6 genes. These results demonstrate an adjuvant effect of short-term supplementation with B. toyonensis and S. boulardii on the immune response against the C. chauvoei vaccine in sheep.

Bacillus Toyonensis BCT-7112T Spores as Parenteral Adjuvant of BoHV-5 Vaccine in a Murine Model.

Bacterial spores of the genus Bacillus are being evaluated as adjuvant molecules capable of improving the immune response to vaccines. In this study, we investigate whether subcutaneously administered spores of B. toyonensis BCT-7112T could enhance a vaccine immune response in mice. Three groups of mice were subcutaneously vaccinated on day 0 and received a booster on day 21 of the experiment, with the following vaccine formulations: 40 µg of recombinant glycoprotein D (rgD) from bovine herpesvirus type 5 (BoHV-5) adsorbed in 10% aluminum hydroxide (alum) without B. toyonensis spores (group 1) and B. toyonensis (1 × 106 viable spores) + 40 µg of rgD adsorbed in 10% alum (group 2); and B. toyonensis (1 × 106 viable spores) without rgD (group 3). Group 2 showed significantly higher titers (P < 0.05) of total specific serum IgG, IgG2a, and neutralizing antibodies, when compared with the groups 1 and 3. A significantly higher (P < 0.05) transcription level of cytokines IL-4, IL-12, and IFN-γ was observed in splenocytes from mice that received the B. toyonensis spores in the vaccine formulation. In addition, stimulation of the macrophage-like cell line RAW264.7 with spores of B. toyonensis markedly enhanced the cell proliferation and mRNA transcription levels of IL-4, and IL-12 cytokines in these cells. Our findings indicated that the subcutaneous administration of B. toyonensis BCT-7112T spores enhanced the humoral and cellular immune response against BoHV-5 in mice.

Association of Bacillus toyonensis spores with alum improves bovine herpesvirus 5 subunit vaccine immune response in mice.

Spores of the genus Bacillus are molecules capable of increasing the vaccine adjuvanticity. Bovine herpesvirus type 5 (BoHV-5) is responsible for meningoencephalitis that causes important economic losses in cattle. BoHV-5 glycoprotein D (gD) is a target of vaccine antigen and plays an important role in host cell penetration. The present study aimed to evaluate the adjuvanticity of Bacillus toyonensis (B.t) spores, live and heat-killed, associated with a vaccine formulated with aluminum hydroxide (alum) and the recombinant BoHV-5 glycoprotein D (rgD) in an experimental murine model. Six experimental groups of mice were subcutaneously vaccinated on day 0 and received a booster on day 21 of the experiment, with the following vaccine formulations: rgD (40 µg) + live spores (2 × 109 CFU); rgD + killed spores; rgD + live spores + alum (2.0 mg); rgD + killed spores + alum; rgD + alum, and rgD + PBS. Mice from rgD + live spores group showed an increase in rgD IgG titers from the 21st day until the end of the experiment. The groups of live and killed spores, associated to alum, had similar levels of IgG titers with no significant difference between each other; however, by the 14th and 28th day until the end of the experiment, presented higher IgG titers in comparison to the rgD + alum group. Moreover, increased serum levels of IgG1, IgG2a, and IgG2b were detected in mice that received spores in the vaccine formulation. The spores associated with alum groups showed neutralizing BoHV-5 antibodies and high mRNA transcription of the cytokines IFN-γ (66-fold), IL-17 (14-fold), and IL-12 (2.8-fold). In conclusion, our data demonstrated that the B. toyonensis spores, live or killed, associated with alum increased the adjuvanticity for BoHV-5 rgD in mice, suggesting the use of B. toyonensis spores as a promising component for vaccine formulations.