1. Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
2. Department of Veterinary Medicine, University of Maryland, College Park, and Virginia-Maryland Regional College of Veterinary Medicine, College Park, Maryland, USA
3. Leidos Biomedical Research, Inc., NCI-Frederick, Frederick, Maryland, USA
4. Departments of Medicine and Microbiology & Molecular Genetics, University of California, Irvine, Irvine, California, USA