1. Department of Microbiology & Immunology, Sealy Center for Vaccine Development, Institute of Human Infections & Immunity, and the Galveston National Laboratory, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1070, USA
2. Department of Biology, Center for Bionanotechnology and Environmental Research (CBER), Texas Southern University, 3100 Cleburne Street, Houston, TX 77004, USA