1. Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 208921;
2. Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa 500112;
3. Bioqual, Inc., Rockville, Maryland 208503;
4. Pathology and Clinical Laboratories, Rancho Los Amigos Medical Center, Downey, California 902424; and
5. Viral Discovery Group, Abbott Laboratories, North Chicago, Illinois 600645