[1] Guys & St Thomas Hosp & Kings Coll, Sch Med, Dept Virol, London SE1 7EH, England
[2] Manchester Royal Infirm, Dept Pathol Sci, Div Virol, Manchester M13 9WL, Lancs, England
[3] Natl Inst Publ Hlth & Environm, RIVM, Res Lab Infect Dis, NL-3720 BA Bilthoven, Netherlands
[4] Acad Hosp Utrecht, Dept Virol, Utrecht, Netherlands
[5] Univ Erlangen Nurnberg, Inst Clin & Mol Virol, Erlangen, Germany
[6] Univ Tubingen, Dept Mol Pathol, Tubingen, Germany
[7] Univ Wurzburg, Inst Virol & Immunobiol, Wurzburg, Germany
[8] Statens Serum Inst, Dept Virol, DK-2300 Copenhagen, Denmark
[9] Hop St Vincent de Paul, Serv Bacteriol Virol & Hyg, F-75674 Paris, France
[10] Huddinge Univ Hosp, S-14186 Huddinge, Sweden
[11] Inst Salud Carlos III, CNM, Madrid, Spain