Determinants of Specificity of the Escherichia coli O157:H7 Bacteriophage PHIV10

Jr. Oats, Purdue University


PhiV10 is a temperate bacteriophage and a member of the Podoviridae family. It has a short noncontractile tail and infects Escherichia coli O157:H7, which is a prevalent foodborne pathogen that is responsible for gastrointestinal disease worldwide. Preliminary screening of PhiV10 to determine its ability to plaque E. coli libraries showed the phage to be specific for E. coli O157:H7, suggesting the necessity of the O157 and H7 antigens for successful infection. The aim of this study was to determine the role of the O157 and H7 antigens in the infection of E. coli O157:H7. Plaque assays showed that PhiV10 infects wild type E. coli O157:H7, but not strains lacking the H7 antigen. Subsequent phage binding assays showed O157 strains lacking the H7 antigen bound PhiV10 similar to O157:H7. However recombinant O157:H7 strains expressing the O antigen acetyltransferase were deficient in binding and also did not form plaques. Since the H7 antigen is not responsible for binding but necessary for infection, it suggests that elements of the flagellar system are responsible for genome insertion. These results suggest that PhiV10 requires both the O157 antigen and the H7 antigen for infection.




Applegate, Purdue University.

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