Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, Virginia, USA.|Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia, USA.|Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, Virginia, USA.|Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, Virginia, USA.|Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia, USA. nsheth@vcu.edu.