Fig 7.

The presence of the toxin-producing WT strain of B. anthracis does not increase survival of a toxin-deficient strain after an i.v. challenge with vegetative bacilli. Analysis of the bacterial burdens in the lungs, spleen, and liver was performed at 24 h after an i.v. challenge with 1.3 × 10⁴ WT CFU/Rb (A), 0.9 × 10⁴ PA− CFU/Rb (B), or 1.3 × 10⁴ WT plus 0.9 × 10⁴ PA− CFU/Rb (C) (n = 3 Rb/group). PA− organisms were distinguished from WT organisms by plating on agar plates with or without kanamycin. Significant differences between WT and PA− organ bacterial burdens were observed (*, P < 0.05). (D) Survival of rabbits after an i.v. challenge with 1.3 × 10⁴ WT compared to 0.9 × 10⁴ PA− CFU/Rb (n = 3 Rb/group) was significantly different (*, P < 0.05).