a, Representative immunoblot of infected BMDMs. Quantification is as described in Fig. 2. b, Quantitative reverse transcription polymerase chain reaction (RT–PCR) of actA transcript abundance. Mean ± s.e.m. for three independent experiments is shown. c, Mice were infected as described in Fig. 2. Data area combination of two independent experiments, n = 10 per strain. The median of each group is represented as a horizontal line. d, Plaque size. Mean ± s.e.m. for three independent experiments is shown. In all panels asterisks denote a significant difference compared to wild type, unless otherwise indicated, as determined by Student’s t-test; *P < 0.05, **P < 0.01, ***P<0.001.