1. Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
2. London School of Hygiene and Tropical Medicine, London, United Kingdom
3. Viral Oncology Section, Acquired Immunodeficiency Syndrome and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
4. University of York, York, United Kingdom