Oral administration of recombinant Bacillus subtilis spores expressing mutant staphylococcal enterotoxin B provides...

Area of Science:

• Microbiology
• Immunology
• Biotechnology

Background:

• Staphylococcus aureus pathogenicity is linked to staphylococcal enterotoxin B (SEB).
• A less toxic, immunogenic mutant form of SEB (mSEB) was developed.
• SEB induces inflammatory cytokines like TNF-α and IL-6.

Purpose of the Study:

• To develop and evaluate recombinant Bacillus subtilis spores expressing mSEB.
• To assess the safety and immunogenicity of orally administered mSEB-expressing spores.
• To determine the protective efficacy of mSEB spores against SEB challenge in a mouse model.

Main Methods:

• Recombinant mSEB and SEB were expressed in prokaryotic plasmids.
• Recombinant Bacillus subtilis spores expressing surface-displayed mSEB were constructed using CotC fusion protein.
• Safety and immune responses (IgA, IgG1, IgG2a) were evaluated in mice after oral spore administration.
• Protective efficacy was assessed by challenging mice with SEB and LPS.

Main Results:

• mSEB-stimulated macrophages showed lower TNF-α and IL-6 levels compared to SEB-stimulated macrophages.
• Oral administration of mSEB spores significantly increased SEB-specific IgA and IgG responses.
• No significant differences in serum biochemical indices were observed between mSEB and control groups.
• Mice receiving mSEB spores showed a 33.3% increased survival rate against SEB and LPS challenge.

Conclusions:

• Recombinant spores stably expressing mSEB were successfully developed.
• Oral administration of these spores induces a robust humoral immune response.
• The developed mSEB-expressing spores offer protection against SEB-induced toxicity in mice.