Acanthopanax senticosus polysaccharide-loaded calcium carbonate nanoparticle as an adjuvant to enhance porcine parvovirus vaccine immune responses

Recently, the strategy of using positively charged nanoparticles as new vaccine delivery systems has been widely investigated for enhancing the anti-infectious disease immune responses and has been found to efficiently improve the immune response through the targeting and activation of antigen-presenting cells. Acanthopanax senticosus polysaccharide (ASPS) is extracted from Acanthopanax senticosus and functions as an effective immunostimulatory drug. The present work encapsulated the ASPS immunopotentiator to the calcium carbonate (CaCO₃) microspheres, and adopted polyethylenimine, a cationic polymer, for coating the microspheres, finally developing the novel nanoparticle (NP) delivery system with positive charge (CaCO₃–ASPS–PEI). As a result, our constructed CaCO₃–ASPS–PEI remarkably up-regulated CD86 and MHCII and activated macrophages, while increasing TNF-α and IL-1β production via macrophages. Moreover, the mice immunized with porcine parvovirus (PPV) antigen adsorbed onto CaCO₃–ASPS–PEI nanoparticles had a significant enhancement in cytokine production, the PPV-specific IgG immune response, and the hybrid Th1/Th2 immune response (dominated by Th1), relative to the remaining groups. Based on the above results, our constructed CaCO₃–ASPS–PEI NPs with positive charge may be used as the efficient adjuvant vaccine delivery system for inducing the long-time potent immune responses.