1. Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon 97331-2902, USA;
2. Archaeal Virology Unit, Department of Microbiology, Institut Pasteur, 75015 Paris, France
3. National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland 20894, USA