Vaccines against mucosal infections

► Effective immunization against mucosal infections usually requires topical-mucosal vaccine administration. ► The mucosal immune system exhibits anatomic compartmentalization related to the migratory patterns of lymphocytes activated at different mucosal sites. ► Sublingual immunization is a promising new approach that results in strong systemic and broadly disseminated mucosal antibody and T cell responses. ► The immunogenicity of oral live vaccines is reduced when used in underprivileged populations in developing countries. ► This “tropical barrier” to oral live vaccines may be due to chronic environmental enteropathy, nutritional problems, aberrant intestinal microflora, concomitant helminth and other infections, and preexisting active or passive (serum and breast-milk antibody) immunity.