1. Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, 800 Rose Street, Lexington, Kentucky 40536-0298
2. Department of Microbiology and Immunology, Tokyo Metropolitan Institute for Neuroscience, Tokyo 183-8526, Japan
3. Liver Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892