[1] GOTHENBURG UNIV,DEPT MED MICROBIOL & IMMUNOL,S-41346 GOTHENBURG,SWEDEN
[2] GOTHENBURG UNIV,DEPT CLIN VIROL,S-41346 GOTHENBURG,SWEDEN
[3] GOTHENBURG UNIV,DEPT NEUROCHEM,S-41346 GOTHENBURG,SWEDEN
[4] ULLEVAL UNIV HOSP,DEPT MICROBIOL,DIV LAB MED,N-0407 OSLO,NORWAY
[5] HUDDINGE UNIV HOSP,KAROLINSKA INST,DIV CLIN VIROL,S-14186 HUDDINGE,SWEDEN
[6] INSERM,U80,F-69008 LYON,FRANCE