1. Institute of Diagnostic Virology; Friedrich Loeffler-Institut, Greifswald - Insel Riems, Germany
2. Department of poultry disease, University of Sadat City, Sadat City, Egypt
3. Private poultry consultant, El Giza, Egypt
4. Virology Department, National Veterinary Research Institute, Vom, Nigeria
5. Institute of Infectology, Friedrich-Loeffler-Institut, Greifswald - Insel Riems, Germany