1. Department of Microbiology and Interdisciplinary Immunology Program; University of Iowa College of Medicine; Iowa City; IA; USA
2. Virus and Prion Laboratory; National Animal Disease Center; Ames; IA; USA
3. Department of Immunology and Gnotobiology; Institute of Microbiology, v.v.i, Academy of Sciences of the Czech Republic; Novy Hradek; Czech Republic
4. Biological Mimetics, Inc.; Frederick; MD; USA