1. Mayo Clinic Graduate School of Biomedical Sciences, Department of Immunology, Mayo Clinic, Rochester, MN 55905, USA
2. Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA
3. Division of Public Health, Infectious Diseases, and Occupational Medicine, Department of Medicine, Mayo Clinic, Rochester, MN 55905, USA