The unifying theme of my research program is the regulation of effector/memory T cell formation in human and mice. The goals are to (1) identify functionally distinct T-cell subsets, (2) study the regulation of their specificity, expansion and effector functions, and (3) define their roles in normal and pathological immune reactions, e.g. (persistent) virus infections, allo-reactivity and immunodeficiency. Detailed knowledge on the regulation and manipulation of T cell immunity is necessary to improve the design of vaccines for infectious and malignant disease.