Characterization of a virulent bacteriophage specific for Escherichia coli O157:H7 and analysis of its cellular receptor and two tail fiber genes.

A virulent phage, named PP01, specific for Escherichia coli O157:H7 was isolated from swine stool sample. The phage concentration in a swine stool, estimated by plaque assay on E. coli O157:H7 EDL933, was 4.2x10(7) plaque-forming units per g sample. PP01 infects strains of E. coli O157:H7 but does not infect E. coli strains of other O-serogroups and K-12 strains. Infection of an E. coli O157:H7 culture with PP01 at a multiplicity of infection of two produced a drastic decrease of the optical density at 600 nm due to cell lysis. The further incubation of the culture for 7 h produced phage-resistant E. coli O157:H7 mutant. One PP01-resistant E. coli O157:H7 mutant had lost the major outer membrane protein OmpC. Complementation by ompC from a O157:H7 strain but not from a K-12 strain resulted in the restoration of PP01 susceptibility suggesting that the OmpC protein serves as the PP01 receptor. DNA sequences and homology analysis of two tail fiber genes, 37 and 38, responsible for the host cell recognition revealed that PP01 is a member of the T-even bacteriophages, especially the T2 family.