PEI-PLGA nanoparticles significantly enhanced the immunogenicity of IsdB 137-361 proteins from Staphylococcus aureus

Staphylococcus aureus seriously threatens human and animal health. IsdB of the iron surface determinant B protein (IsdB) from S. aureus exhibits the strong immunogenicity, but its immunoprotective effect is still to be further promoted. Because PEI-PLGA nanoparticles are generated by PEI conjugate with PLGA to develop great potential as a novel immune adjuvant, the immunogenicity of IsdB is likely be strengthened by PEI-PLGA. Here, PEI-PLGA nanoparticles containing IsdB proteins were prepared by optimizing the entrapment efficiency. Mice were immunized with IsdB -PEI-PLGA nanoparticles to assess their anti-S. aureus effects. The level of IFN-γ, IL-4, IL-17, and IL-10 cytokines from spleen lymphocytes in mice and generation of the antibodies against IsdB in serum was assessed by ELISA, the protective immune response was appraised by S. aureus challenge. IsdB proteins loaded by PEI-PLGA were able to stimulate effectively the proliferation of spleen lymphocytes and increase the secretion of IFN-γ, IL-4, IL-17, and IL-10 cytokine from spleen lymphocytes, and significantly enhance generation of the antibodies against IsdB in serum, reduce the level of bacterial load in liver, spleen and kidney, and greatly improve the survival rate of mice after challenge. These data showed that PEI-PLGA nanoparticles can significantly enhance the immunogenicity of IsdB proteins, and provide an important reference for the development of novel immune adjuvant.