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. 2014 Sep 18;9(9):e107638. doi: 10.1371/journal.pone.0107638

Figure 6. SrtA-specific antibodies were dispensable for protection.

Figure 6

Mice (BALB/c) were immunized three times with SrtA/CTB and euthanized 10 days after the last immunization. Blood and oral wash were taken and samples of sera (IgG 1∶1000; IgA 1∶100) (A), and oral wash (neat) (B) were examined for antibody levels by ELISA (n = 6). (C) B cell deficient mice (µMT) were immunized with SrtA/CTB or received PBS and challenged as in Fig. 2, and euthanized 24 hr after challenge. NALTs were taken and homogenized for plating CFUs. (D) Quantification of CD4+ IL-17+ responses to M1 in NALT of WT and µMT mice before and after immunization. Data are the means ± SEM of three mice per group. ** P≤0.01. (E) C57B/6 mice were immunized as in Fig. 5A. Single-cell suspensions of lymph nodes and spleens were pooled and CD19+ B cells were purified then transfused to naïve WT C57B/6 mice. 24 hr after transfer recipients were challenged i.n. with M1 strain and euthanized 24 hr later for CFUs in NALT.