The molecular basis to Escherichia coli O157:H7 colonisation of the terminal rectum in cattle

Enterohaemorrhagic E. coli (EHEC) O157 causes serious gastrointestinal infections that can be fatal. The bacteria originate primarily from ruminants, in particular cattle. Our previous research has established that the bacteria colonise the final few centimetres of the cow's gut and the aim of the research was to work out the factors that are responsible for this binding/colonisation. Identifying the factors that allow the bacteria to bind at this site means they can be targeted by intervention strategies such as vaccines.

1. The work demonstrated that the type III secretion system is essential for colonization of the terminal rectum of cattle by enterohaemorrhagic Escherichia coli (EHEC) O157:H7.



2. The work demonstrated the importance of the type III effector protein, EspF, for rectal epithelium colonization by EHEC strains. We demonstrated that EspF inhibits the transcytosis of EHEC across M-cells, thereby preventing their presentation to the immune system.



3. The research examined the importance of a number of EHEC surface factors for colonization of bovine rectum primary cells, and concluded that flagella and the type III secretion system were the most significant.



4. As a result these surface antigens have been the main antigens tested in vaccine formulations aimed at blocking or limiting EHEC excretion from cattle.