Survival and systemic colonization of Rag1−/−mice following infection with RB50 and RB50Δ sigE. (A) Groups of Rag1−/− mice (n = 6) were inoculated with 5 × 105 CFU of RB50 (solid line with filled squares) or RB50ΔsigE (dashed line with open triangles) and monitored for survival. (B) Groups of four Rag1−/− mice were inoculated with 5 × 105 CFU of RB50 (white bars) or RB50ΔsigE (light grey bars) and dissected on day 28 post-inoculation for bacterial enumeration in the indicated organs. In a separate experiment, Rag1−/− mice inoculated with RB50ΔsigE were euthanized for bacterial numbers in the indicated organs on day 122 post-inoculation (dark grey bars). The bacterial load is expressed as log10 CFU ± SE. Limit of detection is indicated as the bottom of the y-axis.