1. Laboratory of Veterinary Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium, Laboratory of Physiology and Immunology of Domestic Animals, Faculty of Agricultural and Applied Biological Science, Katholieke Universiteit Leuven, Kasteelpark Arenberg 30, B-3001 Heverlee, Belgium, State Institute for Quality Control of Agricultural Products (RIKILT), Bornsesteeg 45, 6708 PD Wageningen, The Netherlands, and Laboratory of Organic Chemistry, Faculty of...