1. Departments of Medicine, Microbiology and Immunology,McGill University, 1650 Cedar Avenue, L11.513, Montreal, Quebec H3G 1A4, Canada.
2. Departments of Medicine and Microbiology, University of Washington School of Medicine, 1959 Northeast Pacific Street, Seattle, WA 98195–7242, USA.
3. Department of Microbiology, INRS Armand Frappier, 531 Boulevarde des Prairies, Laval, Quebec H7V 1B7, Canada.
4. Department of Internal Medicine, University of Cincinnati, Medical Sciences Building 6065, Post Office Box 670557, Cincinnati, OH 45267, USA.
5. Department of Civil and Environmental Engineering, Northwestern University, A222 Technological Institute, 2145 Sheridan Road, Evanston, IL 60208, USA.
6. Veterans Administration Medical Center–Cincinnati, 3200 Vine Street, Cincinnati, OH 45220, USA.