FIG. 3.
(A) Course of fecal excretion of EHEC O157:H7 following oral challenge of 6-week-old lambs with wild-type strain 85-170 Nalr or the 85-170 Nalr ΔnleH1 ΔnleH2 mutant. Data represent the mean daily fecal count (n = 5 per strain) ± standard error of the mean. (B) CI of EHEC O157: H7 85-170 Nalr ΔnleH1 ΔnleH2 in lambs infected with an inoculum containing a 1:1 ratio of wild-type EHEC and the ΔnleH1 ΔnleH2 double mutant. The null hypothesis that CI = 1 was tested by a two-sided t test and shows that the mean CI postchallenge is significantly less than 1 for all time points where it could be calculated except day 1.