1. Department of Virology and Special Microbial Diagnostic, Statens Serum Institut, Copenhagen, Denmark.
2. Infectious Disease Research Unit, Clinical Institute, University of Southern Denmark, Odense, Denmark.
3. Biomedical Department, Virology Unit, Institute of Tropical Medicine, Antwerp, Belgium.
4. Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom.
5. Viral Evolution and Transmission Unit, San Raffaele Scientific Institute, Milan, Italy.