Bacterial burden within the blood, spleen, liver and lungs of infected mice with A1a strain Schu S
and A1b strain MA00-2987. C57BL/6 J mice (n = 7/strain) were challenged intradermally with 10–20 CFU of F. tularensis strain MA00-2987 (A1b) and Schu S4 (A1a). When mice reached drop point, organs were harvested and blood was taken from each mouse. Significant differences in bacterial burden between the two infecting strains were calculated using MANOVA with an overall Type I error rate of α =0.05 and are designated with an asterisk. The mean bacterial burden is shown as a bar.