1. The Dorrance H. Hamilton Laboratories, Division of Infectious Diseases and Environmental Medicine, Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania.
2. Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania.
3. Department of Microbiology and Immunology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania.
4. Department of Neurology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania.
5. Tibotec Inc., Yardley, Pennsylvania.