1. Laboratory of Virology, Istituto Superiore di Sanità, Rome, Italy1;
2. Laboratory of Virology, Public Health Institute, Tirana, Albania2;
3. Diagnostic Laboratory for Infectious Diseases and Perinatal Screening, National Institute of Public Health and the Environment, Bilthoven, The Netherlands3;
4. Department of Virology, National Public Health Institute, Helsinki, Finland4; and
5. Unité de Virologie Médicale, Institut Pasteur, Paris, France5