1. Mayo Vaccine Research Group, Mayo Clinic, Rochester, Minnesota.
2. Division of Infectious Diseases, Mayo Clinic, Rochester, Minnesota.
3. Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota.
4. Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota.
5. Translational Immunovirology and Biodefense Program, Mayo Clinic, Rochester, Minnesota.
6. Department of Medicine, Mayo Clinic, Rochester, Minnesota.