Immunogenical Study of Chimeric Recombinant Intimin-Tir of Escherichia coli O157:H7 in Mice

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 causes hemorrhagic colitis. The most important reservoirs of this bacterium are domestic ruminant, particularly the cattle. Although it has low prevalence, the severity of consequent diseases of this bacterium brings concerns to develop effective vaccines. This bacterium is able to produce attaching-effacing (A/E) lesions in intestinal epithelial cells and several genes have been implicated in A/E formation. EspA is part of the type III secretion systems that could deliver Tir (translocatedintimin receptor) to the host epithelial cell. The eae gene encoded intimin protein which is essential for colonization of the mucosa and A/E lesions formation by docking to the Tir. Based on these concepts, the immunogenic part of eae and tir genes were constructed and fused together by a linker. The synthetic constructs were subcloned on pET28a + vector and expressed in E. coli BL21DE3. The purified chimeric recombinant protein was injected to mice and the rising antibody was assessed. The results showed that the chimeric recombinant protein induced strong humoral response as well as protection against live oral challenges using E. coli O157:H7. The rIT could reduce bacterial shedding effectively