1. Department of Epidemiology of Microbial Disease; Yale School of Public Health; New Haven CT 06520 USA
2. Gonçalo Moniz Research Center, Oswaldo Cruz Foundation, Brazilian Ministry of Health; Salvador Bahia 40296-710 Brazil
3. Institut Pasteur, Unit of Biology of Spirochetes; 75724 Paris cedex 15 France
4. Department of Pathology and Laboratory Medicine; University of Texas Medical School at Houston; Houston TX 77030 USA
5. Laboratory of Molecular & Structural Microbiology; Institut Pasteur de Montevideo; Montevideo 11400 Uruguay
6. Department of Microbiology and Immunology; West Virginia University; Morgantown WV 26506 USA
7. Department of Structural Biology and Chemistry; Institute Pasteur; 75724 Paris cedex15 France