1. Plum Island Animal Disease Center, Agricultural Research Service, US Department of Agriculture, Greenport, New York.
2. Department of Preclinical Science, Faculty of Veterinary Medicine, Warsaw University of Life Science, Warsaw, Poland.
3. Beltsville Area Research Center, Agricultural Research Service, US Department of Agriculture, Beltsville, Maryland.
4. Department of Pediatrics, Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas.
5. Department of Microbiology and Immunology, Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas.