1. Vaccine and Gene Therapy Institute and Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006
2. Department of Microbiology, Washington University, St. Louis, MO 63110
3. Department of Immunobiology and Arizona Center on Aging, University of Arizona College of Medicine, Tucson, AZ, 85724
4. Department of Pathology, University of Pittsburgh College of Medicine, Pittsburgh, PA 15213