[1] Natl Inst Med Res, MRC, Div Immunoregulat, London NW7 1AA, England
[2] Natl Inst Med Res, MRC, Div Mol Immunol, London NW7 1AA, England
[3] NIAID, Persistent Viral Dis Lab, Rocky Mt Labs, NIH, Hamilton, MT 59840 USA
[4] Univ Aix Marseille 2, CNRS, INSERM, Ctr Immunol Marseille Luminy, F-13288 Marseille 09, France
[5] Tazuke Kofukai Med Res Inst, Osaka 5308480, Japan
[6] Kyoto Univ, Fac Med, Dept Oral & Maxillofacial Surg, Kyoto 6068507, Japan