Effect of mutations in SseB or SseD on intracellular replication of Salmonella. Macrophages were infected at a MOI of 1 with S. Typhimurium wild type (WT), sseB, sseB [psseB] or sseB harboring plasmids for expression of various sseB mutant alleles (sseB [psseB Δx]) (A), or WT, sseD, sseD [psseD], or various strains harboring chromosomal deletion in sseD (B). Extracellular bacteria were killed by gentamicin treatment during 1 h post infection. Intracellular bacteria were quantified after host cell lysis with Triton X-100 at 2 h and 16 h post infection. The x-fold replication is the ratio of viable intracellular bacteria recovered at 16 h versus 2 h post infection. The replication rate was assessed in triplicates and the standard deviation of the mean was calculated. Means and standard deviations of triplicate assays are shown and all experiments were performed at least twice.