A Needle-Free Approach for Topical Immunization: Antigen Delivery via Vesicular Carrier System(s)

Topical immunization (TI) is novel and needle free strategy involving vaccine delivery through topical application of antigen and adjuvant(s) directly or via a suitable carrier system on intact skin. Anatomy and physiology of skin attracts scientists in developing topical carrier system(s) for enhanced delivery of bioactive(s). Numerous techniques i.e. physical, chemical and vesicular carrier systems have been exploited for topical immunization. The present review discuss various vesicular systems i.e. liposomes, niosomes, transfersomes, vesosomes etc. for the efficient topical delivery of various immunogens along with comparative points of their merit(s) in TI. The mechanism of permeation of bioactive(s) through skin route via these carriers to the immune system for development of both cellular and humeral immunity has also been discussed. Moreover, the effect of composition and type of carrier system on type of immunity induced has also been focused to develop new effective carrier system(s) for topical immunization.