1. South Texas Veterans Health Care System, Audie L. Murphy Division,
2. Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78284-7880
3. Department of Pathology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78284-7880
4. Section of Molecular Genetics and Microbiology, University of Texas, Austin, Texas 78712-1095
5. Institute of Cellular and Molecular Biology, University of Texas, Austin, Texas 78712-1095