Plasma anti- C. jejuni antibody levels in mice infected with different C. jejuni strains (experiment 2). Panel A, IgG2b; Panel B, IgG2c; panel C, IgG3; panel D, IgG1; and panel E, IgA. Antibody levels for the first and fourth passage are shown. Bars represent the average OD450/μg plasma protein of mice in passages 1 and 4; whiskers indicate standard error. P values of statistically significant differences between antibody level in passage 1 compared to passage 4 for individual strains are shown on the graph. TSB, sham inoculated control mice.