However, upon infection with this attenuated strain of S. typhimurium, no major changes were evident in histological parameters in the colon, in mucus composition (Figure 2C), or in the level of the secretory protein mucin 2 (Figures 2D,E left graph MUC2), the primary component of the protective mucous layer in the colon (Willemsen et al., 2003). Here, MUC2 is linked to infection.