1. Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
2. Departments of Medicine and Lab Medicine, University of Washington, Seattle, WA 98195, USA.
3. Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
4. National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
5. National Institutes of Health, Bethesda, MD 20892, USA.