1. Department of Virology, Animal and Plant Health Agency (APHA), Addlestone, Surrey KT15 3NB, UK
2. Department of Pathology and Animal Sciences, Animal and Plant Health Agency (APHA), Addlestone, Surrey KT15 3NB, UK
3. WOAH/FAO International Reference Laboratory for Avian Influenza, Swine Influenza and Newcastle Disease, Animal and Plant Health Agency (APHA), Addlestone, Surrey KT15 3NB, UK