1. Department of Immunochemistry, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan
2. Laboratory of Immunochemistry, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
3. Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
4. Department of Infectious Disease Control, International Research Center for Infectious Diseases, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
5. Department of Microbiology and Immunology and the Cancer Research Institute, University of California, San Francisco, San Francisco, California 94143