1. Division of Tropical Medicine, Department of Pediatrics, National School of Tropical Medicine, Baylor College of Medicine and Texas Children's Hospital, Houston, Texas, USA.
2. Texas A&M Natural Resources Institute, College Station, Texas, USA.
3. William T. Shearer Center for Human Immunobiology, Texas Children's Hospital, Houston, Texas, USA.
4. Department of Biology, Angelo State University, San Angelo, Texas, USA.