Upon infection via the aerosol route using a Glas-Col apparatus to deliver~104 CFU of MAB ATCC 19977 smooth morphotype in the lungs ofmice, we identified three strains developing chronic (>28 days) pulmonaryMAB infection: granulocyte macrophage colony stimulating factor (GM-CSF) KO,NOD.Rag.IL2R gamma chain (NRG), and NOD.SCID.IL2R gamma chain (NSG) mice (Table 1). This evidence concerns the gene CSF2 and infection.