1. Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294
2. Laboratory of Molecular Microbiology, NIAID, NIH, Bethesda, Maryland 20892
3. Los Alamos National Laboratory, Los Alamos, New Mexico 87545
4. Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294; Howard Hughes Medical Institute, University of Alabama at Birmingham, Birmingham, Alabama 35294 and Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
5. Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294 and Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294