Scientists and physicians of the Innsbruck campus, working in the related fields of Infection, Immunity, Transplantation and/or Biogerontology, have decided to join forces and have created a structured and multidisciplinary research and training programme of excellence (DK). Their intention is to cooperatively and synergistically investigate genetic and environmental parameters, which destroy the immune homeostasis during host-pathogen interaction, thus leading to opportunistic infections, seldom developing in healthy, but quite often in immuno-compromised subjects.