![]() The use of probiotics before and/or during the vaccination period to modulate the immune response and increase the effectiveness of vaccines against bacterial or viral infections is also receiving increasing interest. Major efforts have been devoted to the development of new mucosal vaccination strategies based on adjuvants able to induce sIgA or on novel delivery systems based on synthetic nanoparticles, viral particles, microbial cells or bacterial spores. ![]() Indeed, adjuvants commonly used in injected vaccines fail to induce sIgA and therefore are not efficient with mucosal antigens, while the lack of appropriate delivery systems does not prevent antigen degradation by enzymes present in the mucosal tissues. This is mostly due to the low immunogenicity of most mucosal antigens and to the lack of efficient adjuvants and delivery systems. However, only few mucosal vaccines are currently licensed for vaccination against viral (Rotavirus, Poliovirus, Influenza type A virus) or bacterial ( Salmonella typhi, Vibrio cholerae) pathogens. Therefore, mucosal, needle-free vaccines are potentially preferable over parenteral vaccinations. While injected vaccines induce specific T cell responses in the bloodstream and serum IgG production but generally fail to induce sIgA, mucosal vaccines administered via the oral or nasal routes induce humoral and cellular immune responses at both the systemic and mucosal sites. For this reason, it is extremely important for a vaccine to induce secretory immunoglobin A (sIgA) antibody production and elicit immune protection at the mucosal surfaces. Mucosal surfaces are the most common route used by pathogens to enter the human and animal body. toyonensis spores significantly contribute to the humoral and cellular responses elicited by a mucosal immunization with spore-adsorbed TTFC, pointing to the probiotic treatment as an alternative to the use of adjuvants for mucosal vaccinations. However, the abundance of members of the Ruminiclostridium 6 genus was found to correlate with the increased immune response of animals immunized with the spore-adsorbed antigen and treated with the probiotic. A 16S RNA-based analysis of the gut microbial composition did not show dramatic differences due to the probiotic treatment. The analysis of the induced cytokines indicated that also the cellular immune response was increased by the probiotic treatment. Spore-adsorbed TTFC was more efficient than the free antigen in inducing an immune response and the probiotic treatment improved the response, increasing the production of TTFC-specific secretory immunoglobin A (sIgA) and causing a faster production of serum IgG. Spore adsorption was extremely efficient and TTFC was shown to be exposed on the spore surface. subtilis spores, a mucosal vaccine delivery system proved effective with several antigens, including TTFC. ![]() Purified TTFC was given to mice by the nasal route either as a free protein or adsorbed to B. toyonensis spores affected the immune response to a mucosal antigen. We used the C fragment of the tetanus toxin (TTFC) as a model antigen to evaluate whether a treatment with B. toyonensis spores has been shown to improve the immune response to a parenterally administered viral antigen in mice, suggesting that probiotics may increase the efficiency of systemic vaccines. Spore-forming bacteria of the Bacillus genus are widely used probiotics known to exert their beneficial effects also through the stimulation of the host immune response. ![]()
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