[177] Center of Vaccinology and Neonatal Immunology

Our objectives are to identify the factors which control the neonatal development of the immune system, using experimental murine models. They have indicated the existence of significant limitations of neonatal CD4 Th1 and CD8 cytotoxic responses required for the clearance of viruses and infected cells. Interestingly, it is however possible to induce adult-like protective T cell responses under specific experimental conditions (vaccine strategies or formulations). We are therefore currently working on the identification of the molecular and cellular determinants of such responses, at the level of dendritic cells, CD4 and/or CD8 lymphocytes. Limitations of antibody responses are more complex and much more prolonged in early life. We study the mechanisms which limit their magnitude, their persistance or their quality, by studying B lymphocytes and their microenvironment (spleen, follicular dendritic cells, bone marrow). We then apply the identified immunological concepts in murine models of protection against viral or bacterial infections. As characteristics of the postnatal neonatal development are largely conserved in mice and human, our experimental models allow us to assess new strategies of vaccine-mediated protection for their capacity to reduce the major infectious disease burdden of the first year of life.Finally, the hypotheses generated in our experimental models are tested in clinical studies of neonatal immunogenicity.