1. Department of Diagnostic and Biological Sciences, School of Dentistry, Medical School, University of Minnesota, Minneapolis, MN 55455, USA
2. Department of Genetics, Cell Biology and Development, Medical School, University of Minnesota, Minneapolis, MN 55455, USA
3. Department of Oral Biology, Joint Health Science Center, University of Florida, Gainesville, FL 32611, USA
4. Mucosal and Vaccine Research Center, Minneapolis VA Medical Center, Minneapolis, MN 55417, USA