Figure 5. The ΔsigI mutant strain is resistant to INH. in vivo.
Two groups of 50 BALB/c mice each were infected with wild-type and ΔsigI M.tb. with an inoculum that implanted ~ 3.5 log10 bacteria per lung by aerosol. Fourteen days post-infection, INH was administered to the mice daily (5 days/week) by oral gavage at doses of 0.5, 1.5 and 6.0 mg/kg/day. (a) Time-do-death analysis of infected mice treated with 0.5 mg/kg/day INH (blue line) or not treated (red line). Solid lines: wild-type. Dashed lines: ΔsigI. Triangle: sham treatment (no INH). Square: 1.5 mg/kg/day INH. Circle: 6.0 mg/kg/day INH. (b) CFU counts in mouse lungs for mice treated untreated or with INH at 1.5 and 6.0 mg/kg/day. All mice infected with the ΔsigI strain died before the day 56 time point. This experiment was performed once, with multiple mice per group. Error bars represent standard deviation.