1. Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA,
2. Vaccine Research Center, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA,
3. Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA,
4. Department of Infection, Immunity and Biochemistry, Cardiff University School of Medicine, Cardiff, Wales, United Kingdom