TLR5−/− (n=19) (A, D), Naip5−/− (n=9) (B, E), and Casp1−/− (n=14) (C, F) mice were immunized twice on day 1 and day 21 and sera collected on days 14 and 35. Naïve, day 14, and day 35 sera were analyzed for IgG1 (A–C) and IgG2c (D–F) isotype specific antibody responses against FliC by ELISA. Data is a combination of 2–3-independent experiments with n = 3–6 per experiment. Statistical analyses were done using Mann-Whitney analysis of individual groups: *= P < 0.05, ** = P < 0.01.