FIG. 8.

Intravenous immunization with SL1344 trxA, SL3261 trxA, or SL3261 and protection against subsequent intravenous challenge with virulent SL1344. Spleen (A) and liver (B) bacterial loads after immunization, followed 20 weeks later with an intravenous challenge with 10⁴ CFU of SL1344. Bacterial counts are shown as the mean log₁₀ and standard errors of one representative experiment from two with similar results. ⧫, all immunized groups were significantly different from the unimmunized group (P < 0.01); *, the SL3261-immunized group was significantly different from the groups immunized with the trxA mutants (P < 0.05), and the group immunized with SL3261 trxA was significantly different from the groups immunized with SL3261 or SL1344 trxA (P < 0.001); **, both the SL3261- and SL1344 trxA-immunized groups were not significantly different from each other (P > 0.05) but were significantly different from the group immunized with SL3261 trxA (P < 0.001). Data were analyzed using one-way ANOVA with Bonferroni's multiple comparison test with n = 4 or 5.