NOS2 and infection: Supported by the remarkable increase of TNF-α levels observed early in the infection in the lungs of iNOS−/− mice, and to further understand the mechanisms of immunoprotection used by this mouse strain to control P.brasiliensis infection, iNOS−/− and WT groups were in vivo depleted of TNF-α and the severity of infection analyzed by CFU counts and pulmonary inflammation.