An Arg × infection interaction was also found for the activity of APE-1, TDG and ANPG in the wall of the ileum (P < 0.001): C. perfringens infection decreased the activity of the above enzymes at the lowest and medium dietary Arg content (Arg90 and Arg100, respectively) and Met concentration of 45% Lys, but not at the highest Arg content (Arg110). This evidence concerns the gene MPG and infection.