1. Department of Comparative Biosciences, University of Illinois at Urbana-Champaign, Urbana, Illinois.
2. Cellular Engineering Technologies, Coralville, Iowa.
3. Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, Illinois.
4. Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois.