1. Department of Clinical Veterinary Science; University of Bristol; Langford House Langford North Somerset BS40 5DU
2. Department of Pathology and Microbiology; University of Bristol; Langford House Langford North Somerset BS40 5DU
3. Max Delbruck Centre for Molecular Medicine
4. Institute of Virology; Charite Medical School; Humboldt University; Berlin Germany
5. Biomedical Research and Study Centre; Riga Latvia