Figure 7

Assessment of virulence phenotypes V. cholerae HD-GYP gene mutants using the infant mouse model. Competition experiments were performed using the infant mouse model. Each mutant was co- inoculated in equal numbers with V. cholerae ΔlacZ (1:1 ratio) into 5-day-old CD1 mice. The bacteria present in the small intestine after 21 hours were enumerated on LB agar plates containing X-gal to differentiate mutant bacteria (blue colonies) from ΔlacZ bacteria (white colonies). The competition index (CI) was calculated as [(mutant CFU/ΔlacZ CFU)output]/[(mutant CFU/ΔlacZ CFU)input]. Each circle represents the CI from an individual animal, and the bars indicate the median. At least 4 mice were used per competition. ***P <0.001, one sample t-test comparing values to a hypothetical value of 1 (i.e., no difference between mutant and wild-type) and by one-way ANOVA.