1. Institute of Hepatology, University College London and University College of London Hospitals, London WC1E 6HX, United Kingdom
2. Department of Sexually Transmitted Diseases, University College London and University College of London Hospitals, London WC1E 6HX, United Kingdom
3. Laboratorio Immunopatologia Virale, Ospedale di Parma, 43100 Parma, Italy
4. Molecular Immunology Group, Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom
5. Cromwell Hospital, London SW5 0TU, United Kingdom