Immunopotentiation of hepatitis B vaccine using biodegradable polymers as an adjuvant.

BACKGROUND/PURPOSE The purpose of this research was to develop an alternative adjuvant for hepatitis B vaccine (HBsAg) that elicits a long-lasting immune response after a single administration. In this study, the suitability of Poly (D, L)-lactide-co-glycolic acid (PLGA), Poly lactic acid (PLA) and Chitosan polymers as adjuvants for HBsAg were investigated. METHODS We used solvent evaporation and emulsion cross-linking techniques to encapsulate HBsAg into the different polymeric systems. The newly developed microparticles were evaluated for vaccine content, particle size distribution, in vitro release and immunogenicity. RESULTS HBsAg-encapsulated PLGA and PLA microparticles were smooth and spherical. However, Chitosan microparticles were homogeneous, and almost spherical, with rough surfaces. The vaccine loading and release patterns varied with the type of polymer used. In this study, Chitosan polymeric microparticles released antigen until day 63 post-injection; however, the release period of the PLGA and PLA systems was shorter. A significant increase in the level of antibodies to HBsAg was induced by all the polymeric microparticles. CONCLUSION The results indicate that Chitosan microparticles are a more efficient adjuvant for HBsAg than PLGA and PLA polymeric microparticles.