1. Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, United Kingdom
2. Department of Infectious Diseases, Palo Alto Medical Foundation, Palo Alto, California 94301
3. Department of Chemistry
4. Laboratory of Molecular Parasitology, Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61802
5. Department of Biophysics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801