1. National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, USA
2. Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
3. Archaeal Virology Unit, Institut Pasteur, Paris, France
4. Integrated Research Facility at Fort Detrick, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Frederick, Maryland, USA