1. Laboratory of Virology and Chemotherapy1 and Laboratory of Clinical and Epidemiological Virology2, Rega Institute for Medical Research, Minderbroedersstraat 10, B-3000 Leuven, Belgium
2. Leiden Institute of Chemistry, Leiden University, PO Box 9502, 2300 RA Leiden, The Netherlands3
3. Unité des Virus Emergents, Faculté de Médecine de Marseille, 27 Boulevard Jean Moulin, 13005 Marseille cedex 5, France4