1. Fort Collins Science Center; United States Geological Survey (USGS); Fort Collins CO 80526 USA
2. Molecular Epidemiology and Public Health Laboratory; Hopkirk Research Institute; Massey University; Private Bag 11222 Palmerston North 4442 New Zealand
3. Department of Microbiology and Immunology; Montana State University; Bozeman MT 59717 USA
4. Institute of Biodiversity, Animal Health and Comparative Medicine; MRC-University of Glasgow Centre for Virus Research; University of Glasgow; G12 8QQ Scotland UK