1. Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 København Ø, Denmark
2. Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
3. Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993, United States