Figure 6.

Impaired 2W1S-specific memory CD4 T cell-mediated immunity to secondary Salmonella-2W1S infection after CLP-induced sepsis. (A) Experimental design—B6 mice were immunized with attenuated Salmonella enterica strain BRD509-2W1S (Se-2W1S; AroA⁻; 10⁶ CFU i.v.) 30 d before sham or CLP surgery. (B) One group of mice (Imm/αCD4) was depleted of CD4 T cells by injecting anti-CD4 mAb GK1.5 i.v. (800 μg on day -7, and 400 μg on days −4 and −3) before second infection with virulent Salmonella-2W1S (10³ CFU i.v.). Bacterial titers in the spleen were determined 7 days later. (C–D) In separate cohorts of attenuated Se-2W1S infected mice, sham or CLP surgery was performed. These mice were then challenged with virulent Se-2W1S (10³ CFU i.v.) (C) 2 or (D) 30 days after surgery. Bacterial titers in the spleen were determined 7 days later. Data shown are representative of 3 independent experiments, with at least 5 mice/group in each experiment. *p ≤ 0.05, **p ≤ 0.01.