1. School of Veterinary Medicine and Biomedical Sciences; University of Nebraska-Lincoln; Lincoln Nebraska USA
2. Laboratory of Immunology, National Institute of Allergy and Infectious Diseases; National Institutes of Health; Bethesda Maryland USA
3. Nebraska Center for Virology, School of Biological Sciences; University of Nebraska-Lincoln; Lincoln Nebraska USA
4. School of Veterinary Medicine; University of California; Davis California USA
5. Department of Medicine, Cell Biology, Neurobiology and Anatomy; Medical College of Wisconsin; Milwaukee Wisconsin USA
6. Center for Biotechnology; University of Nebraska-Lincoln; Lincoln Nebraska USA