1. Plum Island Animal Disease Center, North Atlantic Area, Agricultural Research Service, U.S. Department of Agriculture, Greenport, New York.
2. PIADC Research Participation Program, Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee.
3. Department of Pathobiology and Veterinary Science, University of Connecticut, Storrs, Connecticut.
4. Oncovir, Inc., Washington, District of Columbia.