Figure 3
Antibody immune responses induced by S. Typhimurium with variable OAg lengths in mice. Serum IgG (A), IgA (B), IgG1 (C), and IgG2a (D) specific for S. Typhimurium LPS were measured by ELISA. Error bars represent the standard deviation of 5 replicate samples. *P < 0.05, **P < 0.01 assessed by two-way ANOVA. E Serum bactericidal assay. Serum collected from BSG, ST06, ST07, and ST05-immunized groups and commercial rabbit serum against salmonella O4 (PC) were reacted with wild-type ATCC14028 to determine the survival rate of S. Typhimurium. Error bars represent the standard deviation of 3 replicate samples. F Flow cytometry histograms of C3 complement deposition. Antibody deposition on S. Typhimurium in 10% pooled antiserum from each group of attenuated S. Typhimurium differing for OAg length immunized mice. Wild-type S. Typhimurium incubated with sera from the BSG-inoculated group was set as the negative control (black line), incubated with sera from the ST05 (ATCC14028ΔcrpΔcya)-inoculated group was set as the positive control (green-yellow line). The blue line indicates incubation with sera from ST06 (ATCC14028ΔwzzSTΔcrpΔcya)-inoculated group, and the purple line indicates the incubation with sera from mice immunized with ST07 (ATCC14028ΔwzzST::wzzECO2ΔcrpΔcya).