Inducer-free secretion expression of staphylococcal LukF-PV and LukS-PV in Bacillus subtilis and humoral immune response in mice.

AIM: Bacillus subtilis, an endotoxin-free organism recognized for its safety, has been extensively developed as a platform for recombinant protein production. In this study, we investigated the inducer-free secretion expression of components of the Panton-Valentine Leukocidin (PVL) toxin, LukF-PV and LukS-PV, from Staphylococcus aureus in B. subtilis, and evaluated the immune response to the recombinant proteins in intranasally immunized mice.

METHODS AND

RESULTS

This study investigated the secretion of recombinant LukF-PV and LukS-PV expressed in B. subtilis, using an inducer-free system controlled by a strong Pgrac212 promoter. The genes encoding LukF-PV and LukS-PV were integrated into the B. subtilis chromosome at the lacA locus. LukF-PV was produced at high levels, whereas LukS-PV was expressed at lower levels in an inducer-free manner. The presence of both the recombinant proteins was confirmed by Western blotting and quantified by densitometry. The intranasal administration of concentrated secretions to mice elicited significant antigen-specific IgA and IgG responses, providing both mucosal and systemic immunity.

CONCLUSION

These findings highlight the potential of the inducer-free expression approach for recombinant protein secretion in B. subtilis, supporting its application in vaccine development.