RecombinantBacillus subtilisspores expressing MPT64 evaluated as a vaccine against tuberculosis in the murine model

Abstract

Recombinant Bacillus subtilis spores expressing a TB antigen, MPT64, were tested for their ability to protect mice against tuberculosis challenge. A chimeric gene consisting of the spore coat gene cotB fused to mpt64 was constructed, and expression of a stable CotB-MPT64 hybrid protein of the spore coat verified. Spores were evaluated as a live vaccine and also formaldehyde inactivated. Mice were given three doses of spores or alternatively used in a prime-boost regimen with BCG. The results showed that inactivated recombinant spores were able to reduce the bacterial burden in the lungs of mice to comparable levels to that of BCG. In the prime-boost regimen, both live and inactivated spores showed a reduction in bacterial load in comparison with BCG. ELISPOT and polyfunctional T-cell analysis were performed to examine cellular responses and showed that antigen-specific secretion of Th1 cytokines was stimulated after immunisation with inactive recombinant spores and BCG. In summary, recombinant spores can elicit Th1 responses, which are important for protection against TB disease.

A probiotic treatment increases the immune response induced by the nasal delivery of spore-adsorbed TTFC

“…The use of B. subtilis spores as a mucosal delivery system has been exploited in recent years and tested with several antigens and enzymes [6,21,22]. In addition to TTFC, the binding subunit of the heat-labile toxin (LTB) of Escherichia coli [23,24], the protective antigen (PA) of B. anthracis [20], the C terminus of toxin A of Clostridium difficile [25], the capsid proteins VP26 and VP28 of the White Spot Syndrome virus [26,27] and the MPT64 antigen of Mycobacterium tuberculosis [28] are examples of antigens displayed by B. subtilis spores and tested as mucosal vaccines.…”

Nasal immunization with the C-terminal domain of BclA3 induced specific IgG production and attenuated disease symptoms in mice infected with Clostridioides difficile spores

“…Due to its safety and robustness B. subtilis spores have been widely used as mucosal vaccine vehicles [35][36][37]. B. subtilis spores administered by the nasal route have been shown able to expose the antigen to mucosal-associated lymphoid tissue (MALT) and therefore prompt a strong immune response [38][39][40]. Plus, it is shown that antigens are more protected from enzymatic lysis and have increased stability when displayed into B. subtilis spore surface than free antigen [21,41].…”

Progress in Bacillus subtilis Spore Surface Display Technology towards Environment, Vaccine Development, and Biocatalysis

“…Recombinant B. subtilis spores has the ability to induce systemspecific and mucosal humoral immunity, and Zhou et al [2015] concluded higher amounts of IgG and IgA antibody titers against H. pylori antigen in the mice serum immunized with recombinant spores with urease B. subtilis spores are able to tolerate harsh environments and regrow after inactivation in most conditions. The recombinant spore in active and formaldehyde inactive forms decreased the load of TB antigen in mice in an experiment conducted by Sibley et al [2014], and was considered to be safe for humans, easily transportable, and heat-stable mucosal vaccines. The currently available vaccine, which is either a live-attenuated or inactivated vaccine, needs to be preserved at low temperature and be used through injecting or instilling, which makes their use difficult to some extent, but by using a spore surface-displayed vaccine, all these problems can be alleviated.…”