1. Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
2. KU Leuven-University of Leuven, Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Leuven, Belgium
3. VA Palo Alto Health Care System, Department of Veterans Affairs, Palo Alto, California, USA
4. Department of Medicine, Division of Gastroenterology and Hepatology, Stanford School of Medicine, Stanford, California, USA
5. Department of Microbiology and Immunology, Stanford School of Medicine, Stanford, California, USA