For each mutant line, 8 male mutant mice plus 8 male wildtype control mice are infected i.v. with 0.2ml Salmonella Typhimurium TETc at 6 weeks of age and are monitored over 28 days. On day 14 post infection, 4 of the mutant mice and 4 wildtype control mice are schedule 1 killed. The spleen, liver and caecal contents are extracted and bacteria enumerated by serial dilution and plating onto agar plates. In addition 1 lobe of liver and 1/3 of the spleen will be fixed in formaldehyde for histology. On day 28 post infection the remaining mice are bled under terminal anaesthesia via cardiac puncture. Organs are removed and processed in the same way as describe for day 14 post infection. Blood serum is tested for anti TETc specific antibodies by ELISA assay (IgG, IgG1 and IgG2a). Mice are weighed daily throughout the infection.