Identification and Validation of the Determinants of Variation in T cell Immunity in Health and in Inherited Immunodeficiency Syndromes (360G-Wellcome-211160_Z_18_Z)

Vaccination is a powerful strategy to prevent infectious diseases, by stimulating our immune system to produce antibodies. However, vaccines have not been as successful in boosting immunity against infections that require a different defence called T-cells. This problem is exemplified by tuberculosis, which causes more deaths than any other infection despite the use of the Bacillus Calmette-Guérin (BCG) vaccine, because the protection provided by BCG is variable. I aim to understand why BCG only works in some people. I will investigate the idea that differences in T-cell activation in different people are responsible for differences in the protective effects of BCG. In healthy individuals, I will test T-cell activation in response to a general stimulus. Using these data, I will develop a mathematical model to understand how variation in T-cell responses comes about. I will then In BCG-vaccinate the same individuals and test if my model explains all the variability in responses to BCG and in T-cell control of tuberculosis. These experiments may reveal the molecular switches that are responsible for differences in BCG efficacy. By testing cells from patients with genetic abnormalities in some of these molecules, I will validate their role in providing effective T-cell immunity.