1. Swedish Institute for Infectious Disease Control, Department of Virology, 171 82 Solna, Sweden.
2. Venhälsan, Department of Dermatology and Venereology, Södersjukhuset, Stockholm, Sweden.
3. Karolinska Institute, Microbiology and Tumorbiology Center, 171 77 Stockholm, Sweden.
4. Department of Medicine, Infectious Diseases Unit, Centre for Molecular Medicine, Karolinska Institute, Karolinska University Hospital, Solna, Sweden.