1. Department of Mathematics, Iowa State University, Ames, lowa, USA
2. Bioinformatics and Computational Biology Graduate Program, Iowa State University, Ames, lowa, USA
3. Department of Veterinary Microbiology, Iowa State University, Ames, lowa, USA
4. Department of Infectious Diseases, University of Georgia, Athens, Georgia, USA
5. Poultry Production and Product Safety Research Unit, Agricultural Research Service, United States Department of Agriculture, Fayetteville, Arkansas, USA