1. Division of Biochemistry, Faculty of Pharmacy, Keio University, Minato-ku, Tokyo, Japan
2. Division of Pharmaceutical Sciences, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Kita-ku, Okayama, Japan
3. Japan Society for the Promotion of Science, Kominachi Business Center Building, Chiyoda-ku, Tokyo, Japan
4. Division of Biochemistry, Department of Biomedical Sciences, Nihon University School of Medicine, Tokyo, Japan
5. International Research and Development Center for Mucosal Vaccines, The Institute of Medical Science, The University of Tokyo (IMSUT), Tokyo, Japan