1. Department of Biological Sciences, Border Biomedical Research Center, University of Texas at El Paso, El Paso, TX 79968
2. Department of Biomedical Sciences, Quinnipiac University, Hamden, CT 06518
3. Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205
4. Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14853