4 - Cholera Toxin as a Mucosal Adjuvant

Abstract

This chapter discusses the cholera toxin as a mucosal adjuvent. Mucosal adjuvants are needed to overcome the potential outcome of mucosal antigen exposure. Cholera toxin (CT) enhances the immunogenicity of relatively poor mucosal immunogens when mixed or conjugated together and given orally, thus CT and its B subunit are of great importance as a potential adjuvants for oral vaccines. Unlike many protiens, feeding CT does not induce oral tolerance for antibody responses .Intestinal immunization with CT induces ex -tended memory responses in the mucosa and applies to immunization at other mucosal sites. The properties of CT as a mucosal immunogen also includes antigens delivered with it to mucosal surfaces. CT's mucosal adjuvanticity appears to be related to its immunogenicity. Both of its subunits are required. CT has been effective as a mucosal adjuvant with a wide variety of antigen types. The dose, timing, route, antigen type, and genetic background of the host are all important variables. The mechanism of CT's adjuvanticity might also involve multiple aspects of immune induction in the mucosa, including increased uptake of antigen, enhancement of interleukin-1 and interleukin-6 production by antigen presenting cells, enhancement of T-cell priming; perturbations of regulatory T cells, stimulation of B-cell switching to immunoglobulin A and G, and enhancement of B-cell clonal expansion.