FIG 1.

VapA is the only Vap family member required for growth in macrophages. (A) Schematic representation of the pathogenicity island in wild-type R. equi and the MDM, indicating the positions of genes deleted from the R. equi MDM. Open rectangles represent vap genes and the transcriptional regulators virR and virS. vapI and vapF are pseudogenes. Shaded rectangles represent all remaining genes of the pathogenicity island. (B and C) The intracellular growth of R. equi strains was assessed in murine bone marrow-derived macrophages infected with R. equi 103S, 103S^P−, or the MDM at an MOI of 10. Following incubation for 1 h to allow phagocytosis, monolayers were washed and were treated with amikacin to kill remaining extracellular bacteria (t = 0 h). Monolayers were lysed in triplicate 24 h and 48 h postinfection. (B) Intracellular growth of R. equi strains following infection of macrophages. (C) Fold changes in the CFU count of intracellular bacteria at 24 h and 48 h postinfection relative to that at 1 h postinfection. Error bars represent the standard deviations of the means. The statistical significances of the differences in the fold change in CFU per monolayer between different R. equi strains are given. Data are representative of the results of three independent experiments.