Immunostimulatory biodegradable implants containing the adjuvant Quil-A--Part II: In vivo evaluation

Sustained-release formulations have drawn the attention of formulation scientists working in the area of vaccine research because these systems may reduce the need for booster immunisations. This would be of great advantage especially for the administration of subunit vaccines. The aim of this study was to illustrate the performance of liposome-forming, sustained-release lipid implants containing 2% of the adjuvant Quil-A (QA) (w/w of total lipids) and ovalbumin (OVA) as a model antigen, in an in vivo study using C57Bl/6 mice. QA/OVA-containing lipid implants were administered subcutaneously and stimulated a similar magnitude of immune response when compared with an immediate-release formulation that contained an equivalent amount of adjuvant and antigen but was administered twice. The novel implant system presented here combines the advantages of both sustained release and particulate delivery in one formulation.