Vesicular systems for non-invasive topical immunization: Rationale and prospects

Abstract

The turn of century has witnessed a huge increase in the number of technologies and immunological approaches for new vaccine design. Vesicular carriers, i.e. liposomes, niosomes, transfersomes represent widely exploited class of novel delivery systems for topical applications. Non-invasive vaccination onto the skin using these novel carriers could improve vaccination programs because the procedure requires no specially trained personnel and may avoid risk associated with needle prick. These delivery systems act as adjuvants to enhance the immunogenicity of antigens, which otherwise induce 'weak ' immune response when applied topically. Skin harbours wide variety of immune cells and elicit a strong immunological response, when it comes in contact with any immunogen. Skin shows specific (immunity) vis-à-vis non-speicific (inflammation) responses against foreign substances. Various routes of carrier entry into skin include follicular pathway, normal pores present in the skin, lamellar lipid bodies and through corneocytes. Among various approaches for non-invasive immunization, i.e. physical approaches, chemical approaches and vesicular approaches, latter is gaining wide acceptance for topical vaccination. Vesicular carriers including liposomes, niosomes, virosomes and reconstituted viral envelope transfer the immunogens