1. Department of Virology, Swedish Institute for Infectious Disease Control and Microbiology and Tumorbiology Center, Karolinska Institutet, SE-171 82 Solna, Sweden
2. Unit of Virology, Division of Medical Microbiology, Department of Laboratory Medicine, Lund University, SE-223 62 Lund, Sweden
3. Department of Infectious Diseases/Solna, Karolinska University Hospital, Karolinska Institutet, SE-171 76 Stockholm, Sweden
4. Department of Infectious Diseases/Huddinge, Karolinska University Hospital, Karolinska Institutet, SE-141 86 Stockholm, Sweden