Surface Display of type 2 antigen protein cap on the spores of : An effective mucosal vaccine candidate.

The oral mucosal vaccine has great potential in preventing a series of diseases caused by porcine circovirus type 2 () infection. This study constructed a recombinant Bacillus subtilis RB with Capsid protein () on its spore surface and as a fusion partner. The immune properties of the recombinant strain were evaluated in a mouse model. IgA in intestinal contents and IgG in serum were detected by enzyme-linked immunosorbent assay (ELISA). The results demonstrated that recombinant spores could activate strong specific mucosal and humoral immune responses. In addition, spores showed good mucosal immune adjuvant function, promoting the proliferation of CD3+, CD4+ and CD8+ T cells and other immune cells. We also found that the relative expression of inflammatory cytokines such as IL-1β, IL-6, IL-10, TNF-α and IFN in the small intestinal mucosa was significantly up-regulated under the stimulation of recombinant bacteriophage. These effects are important for the balance of Th1/Th2-like responses. In summary, our results suggest that recombinant RB as a feed additive provides a new strategy for the development of novel and safe mucosal subunit vaccines.