1. Institute of Biomedicine, Protein Chemistry Education and Research Unit, P.O. Box 8, FIN-00014 University of Helsinki, Finland
2. Haartman Institute, Department of Virology, Peptide and Protein Laboratory, P.O. Box 21, FIN-00014 University of Helsinki, Finland
3. Department of Pathology, New York University Medical Center, New York, NY 10016, U.S.A.
4. Haartman Institute, Department of Pathology, P.O. Box 21, FIN-00014 University of Helsinki, Finland