Biodegradable PLGA microspheres as a delivery system for malaria syntheticpeptide SPf66

SPf66 is the first chemically synthesised vaccine to elicit a partial prote ctive immune response against malaria. The aluminium hydroxide (alum)-adsor bed SPf66 vaccine is weakly immunogenic and of poor to moderate efficacy in humans. To investigate the possibility of improving SPf66 vaccine immunoge nicity, a delivery system based on poly- D, L-lactide-co-glycolide (PLGA) m icrospheres was developed and the immune response induced after its subcuta neous administration into mice was evaluated. Microspheres were prepared by a solvent extraction/double emulsion (w/o/w) method and characterised for morphology, size. peptide loading, release profile and peptide integrity. T he in vitro and in vivo results obtained showed that there was no apparent effect of the encapsulation procedure on SPf66 integrity and immunogenicity . The subcutaneous administration of microspheres showed a significantly hi gher immune response (serum IgG levels) than that obtained with alum adsorb ed SPf66 and it was comparable to that of SPf66 emulsified with Freund's ad juvant (FA). These observations illustrate the potential of PLGA microspher es as a delivery system for chemically synthesised antigens. (C) 2001 Elsev ier Science Ltd. All rights reserved.