Immunogenic properties of chimeric protein from espA, eae and tir genes of Escherichia coli O157:H7.

Enterohemorrhagic Escherichia coli (EHEC) comprise an important group of enteric pathogens causing hemorrhagic colitis and hemolytic uremic syndrome. These bacteria need EspA (E) as a conduct for Tir (T) delivery to the host cell and surface arrayed intimin (I) which docks the bacterium to the translocated Tir. This phenomenon leads to attaching and effacing (A/E) lesions. A trivalent recombinant protein called rEIT composed of immunologically important portions of EspA, Intimin and Tir was constructed as a candidate vaccine. For high-level expression, the EIT gene was synthesized with codon bias of E. coli. The immunization was conducted in mice with purified rEIT. The results showed that this chimeric protein induced strong humoral response as well as protection against live challenges using EHEC.