COMPARISON OF THE IMMUNOLOGICAL AND PROTECTIVE RESPONSES ELICITED BY MICROENCAPSULATED FORMULATIONS OF THE F1 ANTIGEN FROM YERSINIA-PESTIS

Purified native F1 antigen from Yersinia pestis was used to assess con trolled-release vaccine delivery systems in poly(lactide-co-glycolide) (PLG) microparticles and liposomes. Antigen encapsulated in PLG micro particles induced high serum titres when injected i.p. in mice: mucosa l IgA was also detected. Mice immunized with F1 in Alhydrogel or PLGs were protected against subcutaneous challenge with Y. pestis. F1 antig en surface-labelled onto liposome vesicles stimulated high serum titre s in Balb/c mice and also induced a mucosal response: F1-labelled lipo somes protected mice against challenge with up to 1 x 10(5) organisms. These findings indicate that a significant immune response is induced by immunizing with F1 formulated in PLGs and liposomes and that prote ction was achieved after only one dose. (C) 1998 Elsevier Science Ltd. All rights reserved.