Affiliation: | Department of Immunology and Department of Laboratory Medicine and Pathobiology, University of Toronto, Medical Sciences Building, 1 King''s College Circle, Toronto, Ontario M5S 1A8, Canada; Department of Paediatric Gastroenterology and Nutrition, Hôpital Robert Debré, 75935 Paris Cedex 19, France; and Institut für Mikrobiologie und Tierseuchen, Freie Universität Berlin, Philippstrasse 13, D-10115 Berlin, Germany |