Nanodelivery Systems for Mucosal Vaccines

The prevalence of new and re-emerging infectious diseases in many developing regions of the world indicates that we urgently need new-generation vaccines. Mucosal vaccine delivery systems have been shown to elicit both mucosal and systemic immune responses for protection against pathogens that mainly infect through mucosal routes. However, the efficacy of such vaccine delivery systems has been limited by mucosal barriers (e.g., pH and degrading enzymes) that limit the delivery of antigens to target tissues. However, although major challenges remain, various nanocarriers have been designed and developed, some of which confer the beneficial properties of nano-size, muco-adhesion, biodegradation, and immune cell-specific targeting; together, these characteristics enhance immunogenicity and prolong the retention time at the mucosal site. Furthermore, vaccination through novel mucosal routes has been shown to facilitate appropriate stimulation of immune responses for individual pathogens. Thus, in the future, various mucosal vaccine delivery systems may prove useful in clinical settings. In this review, we introduce recent advances in mucosal vaccine delivery systems and mucosal routes that are capable of enhancing mucosal immunity, with a focus on the relevant patent literature worldwide.