Moreover, OmpD is recognized as a surface antigen during the immune response [21], so its increased production would result in an enhanced response against Salmonella. In fact, total ROS levels generated by macrophages infected with the ΔompD strain were lower than those of macrophages infected with the wild-type strain at 5 h post infection in the proliferation stage (Figure 3A). This evidence concerns the gene UMPS and infection.