Resorbable lamellar particles of polylactide as adjuvants for influenza virus vaccines

Lamellar particles and microspheres were produced by precipitation from solutions of resorbable, biocompatible, semi-crystalline poly(L-lactide)[PLA] and amorphous poly(DL lactide co-glycolide)[PLG] copolymer, respectively, to investigate their adjuvanticity towards adsorbed influenza virus. Both types of substrate were capable of adsorbing large quantities of virus (> 15% w/w) and retaining virus (> 60% of the initial load) over an 8 week time scale in-vitro. Potent immune responses were obtained in mice after the intra-muscular injection of adsorbed vaccine systems. The response to virus adsorbed on PLA lamellar particles was almost five times that obtained using PLG microspheres and fourteen times that using aqueous vaccine. The lamellar forms of PLA may function as an immunomodulator enhancing phagocytic activity due to their irregular shape and may be useful in improving the immune response to a variety of protein and viral antigens.