Abstract
1Division of Infectious Diseases, Department of Medicine, The Johns Hopkins University, Baltimore, Maryland 21205-2196
5Division of Pediatric Infectious Diseases, Department of Pediatrics Department of Medicine, The Johns Hopkins University, Baltimore, Maryland 21205-2196
2Department of Microbiology and Immunology, Stanford University, Stanford, California 94305
3Department of Medicine, School of Veterinary Medicine, University of California-Davis, Davis, California 95616
4National Institute of Allergy and Infectious Diseases, Bethesda, Maryland 20892