1. Virology Division, U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland 21701
2. Institute for Viral Diseases, Korea University College of Medicine, Seoul, Korea
3. Department of Virology, University of Helsinki, Helsinki, Finland
4. Viral Diseases Division, Centers for Disease Control, Atlanta, Georgia 30333
5. Laboratory of Central Nervous Studies, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland 20205