NOVEL POLYMER-GRAFTED STARCH MICROPARTICLES FOR MUCOSAL DELIVERY OF VACCINES

Recent studies have demonstrated that systemic and mucosal administrat ion of soluble antigens in biodegradable microparticles can potentiate antigen-specific humoral and cellular immune responses. However, curr ent microparticle formulations are not adequate for all vaccine antige ns, necessitating the further development of microparticle carrier sys tems. In this study, we developed a novel microparticle fabrication te chnique in which human serum albumin (HSA) was entrapped in starch mic roparticles grafted with 3-(triethoxysilyl)-propyl-terminated polydime thylsiloxane (TS-PDMS), a biocompatible silicone polymer. The immunoge nicity of HSA was preserved during the microparticle fabrication proce ss. Following intraperitoneal immunization of mice, TS-PDMS-grafted mi croparticles (MP) dramatically enhanced serum IgG responses compared w ith ungrafted MP and soluble HSA alone (P < 0.001). When delivered ora lly, both TS-PDMS-grafted and ungrafted microparticles elicited HSA-sp ecific IgA responses in gut secretions, in contrast to orally administ ered soluble antigen. Indeed, TS-PDMS-grafted microparticles stimulate d significantly stronger serum IgG (P < 0.005) and IgA (P < 0.001) res ponses compared with those elicited by ungrafted microparticles. These findings indicate that TS-PDMS-grafted starch microparticles have pot ential as systemic and mucosal vaccine delivery vehicles.