Adjuvant and antigen delivery properties of virosomes

Dramatic developments in vaccinology and immunology over the last decade have led to the identification of novel antigens, adjuvants and delivery systems, and combinations thereof, that may prove to be highly efficacious vaccines. Despite this explosion in technological developments, in reality, very few novel vaccines for human use have reached the market. Liposomes are one of the most intensively studied areas of vaccine and delivery system research. Several intrinsic features of liposomes lend themselves to their use in vaccines, particularly in terms of safety, versatility and adjuvant properties. Modifications to liposomal structures in terms of additional adjuvants are also playing a role in potential medical applications. The most significant progress to date has been made with virosomes, a novel antigen delivery system that incorporates the haemagglutinin from influenza virus into liposomes and can induce both humoral- and cell-mediated immunity to antigens. This review discusses the presentation and processing of antigens delivered by virosomes, in light of both licensed vaccines and potential vaccine candidates.