1. Division of Cellular and Molecular Biology, Institute of Medical Science, University of Tokyo, Shirokanedai, Minato-ku, Tokyo 108–8639, Japan.
2. Division of Bacterial and Blood Products, National Institute of Infectious Disease, Gakuen, Musashimurayama-shi, Tokyo 208–0011, Japan.
3. Division of Molecular Immunology, Institute for Enzyme Research, University of Tokushima, Kuramoto, Tokushima 770–8503, Japan.