1. Department of Bacteriology II, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashimurayama, Tokyo 208-0002, Japan
2. Institut Pasteur, Molecular Prevention and Therapy of Human Diseases, 25 rue du Dr Roux, Paris 75015, France
3. URAS-CNRS 3012, Paris 75015, France