Recent advances in mucosal vaccine development.

Proper stimulation of the mucosal immune system is critical for the effective protection of mucosal surfaces against colonization and invasion of infectious agents. This requires administration of vaccine antigens directly to various mucosal sites. Due to the low absorption efficiency of mucosally delivered vaccines, however, almost all of the currently marketed vaccines are administered parentally. In addition, sub-optimal immune responses are frequently induced by mucosal immunization and the use of mucosal adjuvants is commonly required. As a result, development of successful mucosal vaccines depends largely on the improvement of mucosal antigen delivery and on the discovery of new and effective mucosal adjuvants. In this review, recent advances in both areas are briefly discussed.