1. Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
2. Department of Pathology, Athens Veterinary Diagnostic Laboratory, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
3. Laboratory of Molecular Biology of Bacterial Pathogens, Institute of Microbiology of the ASCR, Czech Academy of Sciences, 14220 Prague 4, Czech Republic