1 Department of Metabolism, Digestion and Reproduction, Section of Hepatology, Imperial College London, St Mary's Hospital, London W2 1NY, UK. Electronic address: m.lemoine@imperial.ac.uk.
2 Department of Infection Diseases, Imperial College London, St Mary's Hospital, London W2 1NY, UK.
3 Department of Metabolism, Digestion and Reproduction, Section of Hepatology, Imperial College London, St Mary's Hospital, London W2 1NY, UK.
4 Nuffield Department of Medicine, University of Oxford, Oxford, UK.