1. Division of Mucosal Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
2. Research Department, Nippon Institute for Biological Science, Ome, Tokyo, Japan
3. Division of Mucosal Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan International Research and Development Center for Mucosal Vaccines, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
4. Division of Mucosal Immunology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan