1. Seattle Biomedical Research Institute, Seattle, Washington 98109
2. Interdisciplinary Program of Pathobiology, Department of Global Health, University of Washington, Seattle, Washington 98195
3. Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655
4. Division of Infectious Diseases, University of Washington, Seattle, Washington 98195
5. Division of Pediatric Infectious Diseases, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72202