Fig. 4
Immunogenicity of C50336ΔsptP. Procedure for immunization (a). Determination of serum IgG levels (b) and IgG subtype levels (c) at 12 and 26 days post immunization. Stimulation index (SI) of mice lymphocytes determined by splenic lymphocyte proliferation assay using soluble antigen SEAgP (d) or lymphocyte mitogen ConA as a positive control. The vaccinated group received 1 × 107 CFU or 1 × 108 CFU of C50336ΔsptP orally, and the control group received 100 μl of PBS. Data are expressed as the mean ± SEM. *P ≤ 0.05, **P ≤ 0.01