1. Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
2. Division of Infectious Diseases, Department of Medicine, University of Cambridge, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 2QQ, UK
3. School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
4. Department of Infectious Disease, King’s College London School of Medicine, Guy’s Hospital, London SE1 9RT, UK