Affiliation: | Sir Alexander Fleming Building, Department of Life Sciences, Imperial College London, South Kensington, London SW7 2AZ, UK;Institute of Molecular Biology, Ackermannweg 4, 55128 Mainz, Germany;London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK;School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK |