FIG. 1.

EHEC O157:H7 strains that express intimin are shed by inoculated mice for longer durations than an intimin-negative strain. Female BALB/c mice were fed streptomycin-resistant EHEC O157:H7 86-24 Str^r (six mice) and intimin-negative 86-24eaeΔ10 Str^r (five mice) strains, and fecal shedding was monitored. (A) Percentages of mice that shed strain 86-24 Str^r (circles) or strain 86-24eaeΔ10 Str^r (squares) are presented as a function of days postinfection (x axis). (B) Group geometric mean of CFU per gram of feces is shown for strain 86-24 Str^r (circles) or strain 86-24eaeΔ10 Str^r (squares). Groups of 10 female BALB/c mice were fed one of three EHEC O157:H7 86-24eaeΔ10 Str^r isolates that had been separately transformed with plasmids that carried the gene for EHEC intimin-γ, an intimin hybrid of types γ and β, or the vector alone. For 1 week postinfection, fecal pellets were collected and processed. (C) Percentages of mice that shed EHEC O157:H7 86-24eaeΔ10 Str^r that produced intimin-γ (circles), intimin-γβ hybrid (triangles), or no intimin (squares) are shown. (D) Group geometric mean CFU/g feces for EHEC O157:H7 86-24eaeΔ10 Str^r that produced intimin-γ (circles), intimin-γβ hybrid (triangles), or no intimin (squares) is shown. Error bars in panels B and D represent the 95% confidence intervals of the means. Solid horizontal lines represent the limit of detection for the experiments. (E) Results of anti-intimin Western blotting for whole-cell lysates of strain 86-24 Str^r (lane 1), strain 86-24eaeΔ10 Str^r (lane 2), and strain 86-24eaeΔ10 Str^r transformed with the plasmids that carried the genes for intimin-γ (lane 3) or intimin-γβ hybrid (lane 4) or the control plasmid without the intimin gene (lane 5).