In the Institute of Molecular Virology of the GSF â“ National Research Center for Environment and Health in Neuherberg/Munich (Helmholtz Association of German Research Centres) the group is continuing to search for cellular components whose make-up is changed as a result of a prion infection. In collaboration with colleagues from the Technical University of Munich and the University of Heidelberg, the group used micro-array technologies â“ micro-arrays are chips with thousands or tens of thousands of DNA or protein probes - and could demonstrate that the expression of endogenous retroviruses is influenced by infectious prion proteins in tests with mouse cells.