Oral vaccines: directed safe passage to the front line of defense

Abstract

Oral vaccines are safe and easy to administer and convenient for all ages. They have been successfully developed to protect from many infectious diseases acquired through oral transmission. We recently found in animal models that formulation of oral vaccines in a nanoparticle-releasing microparticle delivery system is a viable approach for selectively inducing large intestinal protective immunity against infections at rectal and genital mucosae. These large-intestine targeted oral vaccines are a potential substitute for the intracolorectal immunization, which has been found to be effective against rectogenital infections but is not feasible for mass vaccination. Moreover, the newly developed delivery system can be modified to selectively target either the small or large intestine for immunization and accordingly revealed a regionalized immune system in the gut. Future applications and research endeavors suggested by the findings are discussed.

Keywords: T cell; intestine; mucosa; nanoparticle; oral vaccine; rectogenital infection.

Figure 1. Selective targeting of epithelial cells and dendritic cells by nanoparticle-releasing microparticle oral vaccines for enhanced biomaterial uptake and transport. Conventional enterocytes and specialized epithelial cells overlie the intestinal epithelium. Some underlying dendritic cells extend their dendrites to sample lumen antigen. Cell-specific targeting of these cells may enhance oral vaccine efficacy by improving mucosal uptake, transepithelial transport and subsequent antigen processing and presentation.