1. Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, U.K.
2. Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K.
3. Molecular Immunity Unit, Department of Medicine, MRC Laboratory of Molecular Biology, University of Cambridge, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, U.K.
4. Cambridge Centre for Lung Infection, Royal Papworth Hospital, Cambridge, CB23 3RE, UK