1. Science and Mathematics Division, Eastern Oklahoma State College, Idabel, Oklahoma 74745.
2. Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi 39762.
3. Department of Pathology, University of Georgia, Athens, Georgia 30602.
4. Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi 39762.
5. Department of Microbiology and Immunology, Cornell University, Ithaca, New York 14853.
6. 9717 Wild Mountain Drive, Sherwood, Arkansas 71754.