Skin immunization made possible by cholera toxin

Immunization using an application to the skin surface, without physical penetration by needles, would greatly increase the ease of vaccination. In orally and nasally administered vaccines, the bacterial product cholera toxin (CT) is commonly used to enhance the immune response. We found that when CT was applied to the surface of the skin, it stimulated an immune response to vaccine components such as diphtheria or tetanus toxoids. Immunization can thus be achieved by the simple application of a mixture of CT and vaccine components without penetration or disruption of the skin.