1. Center for Molecular Medicine Cologne and Institute of Virology, University of Cologne, Germany
2. Institute of Virology, Saarland University, Homburg/Saar, Germany
3. Department of Gynecology and Obstetrics, Saarland University, Homburg/Saar, Germany
4. Department of Pathology, Saarland University, Homburg/Saar, Germany