IL6 and infection: The secreted IL-6 levels in both YZU0463- and YZU2855- infected cells were similar and significantly higher than those in cells infected with YZU0463ΔfliC, YZU2855ΔfliC, and YZU2855fliC→fljB at both 3 h and 6 h post-infection (Figures 3A and B).