Viruses, bacteria and other parasites pose a permanent threat to the survival of organisms. Most living creatures therefore have ingenious defence strategies in place with which to fight such invaders. The scientists at the Max Planck Institute of Immunobiology and Epigenetics focus on the development and functioning of such strategies. They examine how the immune system emerged in the course of evolution and how it develops from the embryo to the adult organism. They also analyse genes and molecules which are important for a functioning immune system. For example, they look into the factors controlling the maturation of immune cells and how chemical changes in the genetic substance DNA influence the immune defence. In addition to immunobiology, another research focus was established at the Institute in 2007: epigenetics. This science focuses on the inheritance of characteristics that are not caused by changes in the DNA sequence. This new research focus is expected to lead to a better understanding of diseases and cancers that cannot be defined in strictly genetic terms.