1. Department of Microbiology and Immunology, University of Texas Medical Branch (UTMB), Galveston, TX 77555, USA
2. Department of Veterinary Sciences, University of Texas M. D. Anderson Cancer Center, Bastrop, TX 78602, USA
3. Center for Biodefense and Emerging Infectious Diseases, UTMB, Galveston, TX 77555, USA
4. Sealy Center for Vaccine Development, UTMB, Galveston, TX 77555, USA