The prevalence of asthma in Canada (and worldwide) has been increasing over the last 20 years with currently over 3 million Canadians suffering from it. Asthma appears to result from environmental influences directing a genetically predisposed host towards a pro-allergic, Th2-dominated immune response. Studies in humans and animals identify the time around birth and early infancy as a period during which the decision of pro-allergic versus non-allergic immune responses to environmental stimuli appears to be made. Presumably this is the reason why the incidence of first diagnosis is highest in infants and children, although asthma can occur at any age. The very fact that all three components (environmental, genetic and developmental) are necessary for asthma to occur also offers the opportunity to intervene early in life through e.g. vaccination against allergies. Vaccination as a strategy to prevent or cure asthma is a tremendous opportunity. An ideal vaccine would be one that prevents or cures asthma after only one dose and protects for life. It is well established that the whole heat-killed bacterium Listeria monocytogenes (Lm) given as an adjuvant along with model allergens effectively prevent allergic sensitization and/or allergic inflammation in adult animals following local allergen challenge. We have successfully developed a novel, live, but highly attenuated neonatal vaccine platform based on the bacterium Listeria monocytogenes (Lm). Our published data suggest that our Lm-based vaccine platform is capable of inducing strong anti-allergic immune responses for an entire life only after one dose given to newborn mice. Now we have investigated whether our Lm-based vaccine platform will provide protection from allergic reactions upon challenge with the allergen, after only one immunization given around birth. Our specific aim addressed the following objective: Do our Listeria monocytogenes vaccine strains producing model allergen ovalbumin (OVA) and inducing a strong Th1 response, prevent allergic reactions upon challenge with the allergen in a neonatal mouse model?