FIG. 1.

Susceptibility to Salmonella serovar Choleraesuis avirulent strain 31N-1 of IL-2/IL-15Rβ-or IL-2-deficient mice. (A) The number of serovar Choleraesuis cells recovered from peritoneal cavities of IL-2/IL-15Rβ- or IL-2-deficient mice (−/−) or their littermate control mice (+/−) after i.p. infection with serovar Choleraesuis (2 × 10⁶ CFU). The number of bacteria was determined by a colony formation assay in tryptic soy agar plates. The data are representative of three independent experiments and are shown as the means ± standard deviations (SDs) for three to five mice. Statistically significant differences (∗) between deficient mice and control mice are shown (P < 0.001). (B) Early production of cytokines in the sera of IL-2/IL-15Rβ^−/− or IL-2^−/− mice after i.p. infection with serovar Choleraesuis (2 × 10⁶ CFU). Sera were collected from deficient mice or wild-type control mice on day 0, 3, or 6 after i.p. challenge with serovar Choleraesuis. The amounts of IFN-γ or IL-12 p40 in the serum were determined by an enzyme-linked immunosorbent assay. Data were obtained from three separate experiments and are expressed as the means ± SDs for three to five mice.