1. Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland Campus, College Park, MD 20742–3711
2. National Veterinary Services Laboratory, USDA-APHIS-VS, Ames, IA 50010
3. University of Maryland-Eastern Shore, Princess Anne, MD 21853–9802
4. Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742–4451