1. Influenza Branch, Mail Stop G-16, DVRD, NCID, Centers for Disease Control and Prevention, 1600 Clifton Road, N.E., Atlanta, Georgia
2. Department of Microbiology, Mount Sinai School of Medicine, New York, New York 10029
3. Department of Molecular Pathology, Armed Forces Institute of Pathology, Rockville, Maryland 20850
4. Southeast Poultry Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, 934 College Station Road, Athens, Georgia 30606
5. Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin 53706
6. Department of Molecular Cell Biology, Vrije University, Amsterdam, The Netherlands