Functional Exploration of the Immune Response Using the B-Subunit of Cholera Toxin Administered by Mucosal Way in Healthy Adult Volunteer: Potential Role in Development of Vaccine Processes

The immense majority of the infections involve the mucosal surfaces as a gateway of the pathogenic agent. These mucosal surfaces are mainly represented by the gastrointestinal, respiratory and urogenital tract. These mucosal surfaces contain a highly developed immune system, which can exploit in a mucus vaccine approach to fight against infectious agents upon their penetration in the body. It has been established that to be effective against infection mucosa, a vaccine must stimulate the local immune system. This objective is reached much more efficiently when the vaccine is administered by mucosal way (oral, nasal) than by the parenteral classical way. Recent works allowed developing a new non invasive system of administration of vaccines. It is based on the mucosal administration (oral, nasal, rectal, vaginal) comprising a combination of antigen bound (either chemically or by genetic fusion) to the non-toxic subunit of cholera toxin or CTB (Cholera Toxin B subunit). This subunit has an exceptional affinity for GM1 ganglioside expressed on the surface of all nucleated cells. So, the mucosal administration (by oral or nasal route) of a low dose of an antigen linked to the CTB - Mucosal vector with immunomodulatory properties - Leads powerful secretor immune responses in the exposed mucous As well as in distant mucous, with a strong production of secretories IgA.

The developed methods of exploration have to allow to characterize the cells which live (or which migrate) in the mucous membrane investigated on the functional and phenotypic plan.

This research should lead to a range of standardized operating procedures, allowing to evaluate the immunogenicity of vaccines candidates to the mucous administration and of predictive markers of the type of immune response generated.

The main objective of the study is to analyse at the healthy voluntary subjects the systematic immunizing answer induced after nasal, oral or sublingual administration of the CTB from blood samples - the lymphoid "compartment" the most accessible at the man- from saliva and from nasal wash. The immune response after administration of the CTB By sublingual way should be comparable in that of two other ways in term of intensity of the response, however, with a different IgA / IgG report.

The secondary objective of the study is to establish a range of tests to predict the character and the intensity of this response by analyzing the expression of B cells certain surface molecules marking their future for the production of Antibodies.