PEI-PLGA nanoparticles significantly enhanced the immunogenicity of IsdB_137-361 proteins from Staphylococcus aureus

Staphylococcus aureus seriously threatens human and animal health. IsdB_137-361 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_137-361 is likely be strengthened by PEI-PLGA.

Here, PEI-PLGA nanoparticles containing IsdB_137-361 proteins were prepared by optimizing the entrapment efficiency. Mice were immunized with IsdB_137-361 -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_137-361 in serum was assessed by ELISA, the protective immune response was appraised by S. aureus challenge.

IsdB_137-361 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_137-361 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_137-361 proteins, and provide an important reference for the development of novel immune adjuvant.