Affiliation: | (1) Department of Microbiology, School of Medicine, University of Virginia, 22908 Charlottesville, VA, USA;(2) the Molecular Biology Institute, School of Medicine, University of Virginia, 22908 Charlottesville, VA, USA;(3) Present address: Department of Microbiology, University of Illinois, 61801 Urbana, IL, USA;(4) Present address: Department of Physiological Chemistry, University of Wisconsin, 53706 Madison, WI, USA |