FIG 5.

Vaccination with the batA KO mutant strain provides protective immunity against back-challenge with a lethal dose of WT B. mallei bacteria. BALB/c mice were vaccinated intratracheally with 10⁴ CFU of the batA KO and 10⁵ CFU of the ilv KO mutant strains using a Microsprayer device. Thirty days later, the animals were back-challenged with ∼10 LD₅₀ of WT B. mallei ATCC 23344 and monitored daily for clinical signs of illness and morbidity. Age- and weight-matched naive BALB/c mice were used as controls. (A) Kaplan-Meier survival curves. (B) Survival data during the acute and chronic phases of infection. (C, D, and E) Tissues were collected from mice that survived back-challenge (day 45), homogenized, diluted, and spread on agar plates to determine bacterial loads. The symbols show data for individual animals; the horizontal lines represent the mean total CFU for each group.