Fig 6.

The presence of the toxin-producing WT strain of B. anthracis does not increase the survival of a toxin-deficient strain after a pulmonary spore challenge. Bacterial burdens in the LALN and spleen were analyzed at 24 h after a pulmonary challenge with 1.8 × 10⁶ WT plus 1.5 × 10⁶ PA− spores/Rb (A) or 0.9 × 10⁶ WT plus 1.4 × 10⁷ PA− spores/Rb (B) (n = 3 Rb/group) or at 48 h after a pulmonary challenge with 0.9 × 10⁶ WT plus 1.4 × 10⁶ PA− spores/Rb (C) or 0.9 × 10⁶ WT plus 1.5 × 10⁷ PA− spores/Rb (D). (Three Rb/group were infected, but two Rb died prior to harvest.) PA− organisms were distinguished from WT organisms by plating on agar plates with or without kanamycin. Significant differences were observed between WT and PA− bacterial burdens in the LALN or spleen (*, P < 0.05).