1. Department of Bacteriology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi Mizuho-cho Mizuho-ku, Nagoya 467-8601, Japan
2. Department of Molecular Bacteriology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho Showa-ku, Nagoya 466-8550, Japan
3. Department of Microbiology, Aichi Prefectural Institute of Public Health, Nagare 7-6, Tsuji-machi, Kita-ku, Nagoya 462-8576, Japan