1. Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, WA 98155, USA.
2. Department of Pediatrics, University of Washington, Seattle, WA 98155, USA.
3. Immunology and Molecular Pathogenesis Graduate Program, Emory University, Atlanta, GA 30322, USA.
4. Department of Cell and Molecular Physiology, University of North Carolina, Chapel Hill, NC 27599, USA.
5. Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27599, USA.
6. Department of Microbiology, University of Washington, Seattle, WA 98155, USA.
7. Department of Medicine, University of Washington, Seattle, WA 98155, USA.
8. Department of Immunology, University of Washington, Seattle, WA 98155, USA.