Fig 7.
SifA and SsaV mutants are more susceptible than WT S. Typhimurium to killing by bone marrow-derived macrophages. Macrophages were grown from the bone marrow of BALB/c.D2Slc11a1 congenic mice as described in Materials and Methods. There was no significant difference in the numbers of WT and ssaV and sifA mutant bacteria ingested by the macrophages. After 16 h of incubation, the survival of the two mutant strains was significantly less than the survival of WT Salmonella in both untreated cells and cells that were activated by pretreatment with TNF-α. The activated macrophages were bactericidal for all three strains.