PREVENTION AND CONTROL OF SHIGA-TOXIGENIC ESCHERICHIA COLI IN LIVESTOCK
Location: Meat Safety & Quality Research
Title: Association of Escherichia coli O157:H7 tir polymorphisms in human infection
Submitted to: BMC Infectious Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 9, 2007
Publication Date: August 24, 2007
Citation: Bono, J.L., Keen, J.E., Clawson, M.L., Durso, L.M., Heaton, M.P., Laegreid, W.W. 2007. Association of Escherichia coli O157:H7 tir polymorphisms with human infection. BMC Infectious Diseases. 7:98.
Interpretive Summary: An important factor in the ability of of E. coli O157:H7 to cause infection is the ability of this bacterium to adhere to epithelial cells. Proteins from two bacterial genes, tir and eae, are responsible for adherence to epithelial cells. Tir is injected by the bacteria into the epithelial cell where it integrates into the cell membrane and acts as a receptor for the eae gene product, a protein called intimin. By sequencing 10 human and 14 bovine isolates, we identified 11 tir sequence variants. Two of the variants were able to distinguish between human and bovine sources. While many host, bacterial, and environmental factors impact whether or not clinical disease results from natural exposure to bacteria, it appears that tir sequence differences may explain some of the variation in the clinical outcome resulting from human exposure to E. coli O157:H7.
Tir, the translocated intimin receptor protein produced by shiga-toxigenic Escherichia coli (STEC) O157:H7, is necessary for tight adherence to intestinal epithelial cells. Nucleotide sequence variation within the tir gene of human and bovine STEC O157 isolates was identified and compared. Two tir polymorphisms were associated with STEC O157 human isolates.