1. Department of Molecular Biotechnology, Ghent University, Ghent, Belgium
2. Laboratory of Physiology and Immunology of Domestic Animals, Catholic University of Leuven, Leuven, Belgium
3. Institut für Geflügelkrankheiten, Justus-Liebig-Universität, Giessen, Germany
4. Istituto Zooprofilattico Sperimentale della Lombardia e dell' Emilia Romagna, Sezione di Pavia, National Reference Laboratory for Animal Chlamydioses, Pavia, Italy
5. United States Department of Agriculture, National Animal Disease Center, Ames, Iowa
6. Institute for Environmental Health, Seattle, Washington