[1] Heinrich Pette Inst Expt Virol & Immunol, D-20251 Hamburg, Germany
[2] Hannover Med Sch, D-30625 Hannover, Germany
[3] Univ Hamburg, Hosp Eppendorf, D-20249 Hamburg, Germany
[4] Univ Freiburg, D-79106 Freiburg, Germany
[5] EUFETS AG, D-55743 Idar Oberstein, Germany