On day-28 post-infection, Ig heavy chain V region MOPC 104E and keratin type II cytoskeletal 6A were up-regulated, whereas 11 proteins were down-regulated in the infected mouse: alkaline phosphatase, serine protease inhibitors (A3G, A3N, and A3F), macrophage erythroblast attacher, keratin type I cytoskeletal 40, actins (alpha skeletal and cardiac muscle), Ig kappa chain, glutathione peroxidase 3, and complement C3. The gene discussed is C3; the disease is infection.