1. Department of Virology, Statens Serum Institut, 5 Artillerivej, DK-2300 Copenhagen S, Denmark
2. Institute for Medical Microbiology and Immunology, University of Copenhagen, Denmark
3. Department of Infectious Diseases, University Hospital of Copenhagen, Denmark
4. Department of Infectious Diseases, University Hospital of Hvidovre, Denmark
5. Bavarian Nordic Research Institute, Martinsried, Germany
6. Center for Biological Sequence Analysis, BioCentrum-DTU, Technical University of Denmark, Lyngby, Denmark