1. Department of Microbiology and Immunology; Tohoku University School of Dentistry; Sendai Miyagi 980-8575 Japan
2. Department of Periodontics and Endodontics; Tohoku University School of Dentistry; Sendai Miyagi 980-8575 Japan
3. Department of Microbiology; Tohoku Pharmaceutical University; Sendai Miyagi 981-8558 Japan
4. Laboratory for Immunopharmacology of Microbial Products, School of Pharmacy; Tokyo University of Pharmacy and Life Science; Hachioji Tokyo 192-0392 Japan
5. Tokyo Research Institute; Seikagaku Corporation; Higashiyamato Tokyo 207-0021 Japan
6. Department of Oral Pathobiological Science; Hokkaido University Graduate School of Dental Medicine; Sapporo Hokkaido 060-8586 Japan
7. Division of Infectious Genetics, Department of Microbiology and Immunology, The Institute of Medical Science; The University of Tokyo; Bunkyo-ku Tokyo 113-8654 Japan