Abstract
To develop an effective, safe, and convenient vaccine for the prevention of highly pathogenic avian influenza (HPAI) H5N1, we have constructed a recombinant Bacillus subtilis strain (B.S.-HA) expressing the hemagglutinin (HA) protein. Then we evaluated the immune function in chicken bone marrow derived dendritic cells (BM-DCs), and the immune response after oral immunization. Our results show that the recombinant Bacillus subtilis B.S.-HA could be sampled by BM-DCs in vitro and increase the BM-DCs major histocompatibility complex (MHC) II phenotype. The weight, height of the small intestine villus, and lymphoid tissue area of the ileum increased significantly in B.S.-HA immunized chickens (P < 0.05 or P < 0.01). B.S.-HA induced the secretion of cytokines and the expression of Toll-like receptors in the trachea and small intestine (P < 0.05 or P < 0.01). In addition, B.S.-HA elevated the specific IgA titers in the trachea, IgG and HI antibody titers in serum (P < 0.05 or P < 0.01). Therefore, B.S.-HA provides a potential novel strategy and approach for developing an H5N1 vaccine.
Highlights
Bacillus subtilis is a nonpathogenic Gram-positive bacterium, a novel probiotic and biocontrol bacterium
B.S.-HA could be sampled by chicken bone marrow-derived dendritic cells (BM-DCs), and it induced the expression of major histocompatibility complex (MHC) II
The pHT43 or pHT43-HA plasmid was transformed into B. subtilis WB800N by electroporation, and the HA protein was immunodetected using an HA antibody
Summary
Bacillus subtilis is a nonpathogenic Gram-positive bacterium, a novel probiotic and biocontrol bacterium. B. subtilis is widely used as a vehicle for heterologous antigen expression and protective immunization[8,9]. Our previous study demonstrated that B. subtilis remarkably improved the immunoprotective efficacy of whole inactivated H5N1 influenza virus via oral immunization in chickens by enhancing local and systemic immune responses[10]. B. subtilis can induce non-specific immune response against infection, increase IgA production, and regulate the balance of the Th1 and Th2 pathways[11]. A recombinant B. subtilis strain (B.S.-HA) expressing hemagglutinin (HA) protein was constructed, and the efficacy of oral immunization of B.S.-HA was evaluated in chickens. B.S.-HA could be sampled by chicken bone marrow-derived dendritic cells (BM-DCs), and it induced the expression of major histocompatibility complex (MHC) II
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