In defense of mucosal surfaces. Development of novel vaccines for IgA responses protective at the portals of entry of microbial pathogens.

A common mucosal immune system occurs in mammalian species, where antigen stimulation of BALT and GALT induces an exodus of specific lymphocytes that home to the various mucosal effector sites. These responses are finely regulated and T cells and cytokines are of central importance for ultimate plasma cell differentiation and for production of S-IgA antibodies in our external secretions. The current need for vaccines, including those to respiratory, gastrointestinal, and genitourinary tract infections as well as the universal efforts to develop immunity to HIV and AIDS, compels us to continue to better understand how we can use the common mucosal immune system to advantage for eventual prevention of infectious diseases. This article summarizes the various antigen delivery strategies and progress of oral vaccines for induction of protective mucosal immune responses to various viral and bacterial diseases.