Figure 1.

IκBζ^−/− mice exhibited enhanced susceptibility after challenge with lethal Salmonella infection even following pre-vaccination. (A) Wild-type (WT) and IκBζ^−/− mice were orally challenged with 10⁷ CFU of a lethal wild-type Salmonella strain (UK-1) per mouse (n = 11/group). ns; not significant (log-rank test). Experiment came to the end at 25 days of post infection. Survived mice was sacrificed. (B) Wild-type and IκBζ^−/− mice were immunised by oral administration with 10⁹ CFU of a recombinant attenuated Salmonella vaccine strain (RASV) per mouse twice at 2-week intervals. Mice were challenged with UK-1 at 10⁷ CFU per mouse 14 d after the final RASV oral immunisation. The survival of mice was monitored following challenge (n = 13 for WT/RASV/UK-1, n = 12 for IκBζ^−/−/RASV/UK-1; ^***P < 0.001, based on log-rank test). (C,D) Wild-type and IκBζ^−/− mice were immunised with oral administration of 10⁹ CFU of RASV per mouse twice at 2-week intervals. (C) Liver tissues and (D) spleens from the mice were homogenised to determine the CFU of RASV at unimmunised, 14 d (D14) after the first administration with RASV, and 14 d after the second administration (D28). Data are representative of three independent experiments. ns, not significant; ^*P < 0.05, ^**P < 0.01, and ^***P < 0.001 based on ANOVA with Bonferroni’s multiple comparison test.