1. University of Innsbruck, Department of Pharmacy, Innrain 80/82, 6020 Innsbruck, Austria
2. University of Vienna, Department of Pharmaceutical Chemistry, Althanstraße 14, A-1090 Vienna, Austria
3. KU Leuven Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, Herestraat 49, B-3000 Leuven, Belgium