1. Department of Molecular Biology and Immunology, University of North Texas Health Science Center in Fort Worth, Fort Worth, Texas 761071;
2. Department of Microbiology and Immunobiology Vaccine Center, University of Alabama at Birmingham, Birmingham, Alabama 352942; and
3. Department of Mucosal Immunology, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan3