Furthermore, a series of experimental studies had shown that dietary supplementation of a non-cytotoxic dose of Mn could up-regulate sod2 mRNA level in chickens [27,28], illustrating that increases of H2O2 by dietary Mn-induced MnSOD activity probably act as intracellular messenger to upregulate the production of proinflammatory cytokines for fighting bacterial infections. The gene discussed is SOD2; the disease is bacterial infectious disease.