Coordinated Regulation of Virulence during Systemic Infection of Salmonella enterica Serovar Typhimurium
Primary bone marrow-derived macrophages were prepared as described in Materials and Methods and infected at an input MOI of 100 by low speed centrifugation onto cells in identically seeded wells (on average our conditions result in 1–2 intracellular bacteria per cell). The bacteria were opsonized in 10% normal mouse serum for 20 min prior to infection. Intracellular survival was measured at 30 min (grey), 2 h (white) and 18 h (black) post infection from at least three independent assays. Times refer to the time after centrifugation for macrophage infection. The results suggest that there is not a one to one correlation between systemic mouse infection and survival/replication in primary macrophages.