1. Biochemisches Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
2. Pharmazentrum Universität Basel, Klingelbergstrasse 50/70, CH-4056 Basel, Switzerland
3. Swiss National Center for Retroviruses, Institute for Medical Virology, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
4. Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, P.O. Box 2543, CH-4002 Basel, Switzerland
5. Département de Pédiatrie, Hôpital des Enfants HUG, CH-1211 Genève, Switzerland