1. Dipartimento di Scienze Farmaceutiche, Università di Ferrara, 44100 Ferrara, Italy, Rega Institute for Medical Research, Laboratory of Virologyand Chemotherapy, Minderbroedersstraat 10, B-3000 Leuven, Belgium, and Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Surugadai, Kanda, Chiyoda, Tokyo 101-0062, Japan