1 Galveston National Laboratory, Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, TX 77550-0610, USA.
2 Galveston National Laboratory, Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, TX 77550-0610, USA. Electronic address: twgeisbe@utmb.edu.