FIG 1.

Inhibition of V. cholerae motility is the primary mechanism of immune protection. Two types of nonmotile mutant, flagellated but nonmotile (ΔmotY) (A) and aflagellate (ΔflaACEDB) (B), were competed against the motile wild-type strain (WT) in either naive or immune pups. Five-day-old suckling mice born to mice mock immunized or immunized with OMVs produced by strains indicated on the x axes were challenged with equal mixtures of the competing V. cholerae strains. The competitive index was calculated as the ratio of nonmotile to wild type after correcting for the input ratio. Each symbol represents sample from one mouse. Bars are medians. Statistical analysis was done using Mann-Whitney U test with Kruskal-Wallis test for multiple-variable groups (*, P < 0.0001).