Author information:
(1)Section of Microbiology, Medical Rresearch Council Centre for Molecular 
Bacteriology and Infection, Imperial College London, London SW7 2AZ, England, 
UK.
(2)Section of Microbiology, Medical Rresearch Council Centre for Molecular 
Bacteriology and Infection, Imperial College London, London SW7 2AZ, England, UK 
s.mostowy@imperial.ac.uk.