FIG. 2.

Analysis of anti-VirB (α-VirB) antibodies in sera from 12 goats experimentally infected with wild-type B. melitensis 16M or one of its isogenic mutants BMΔvirB2, BMΔasp24, or BMΔcydBA and from 12 uninfected controls. Blood was collected 8 weeks after infection, and levels of IgG specific for VirB1, VirB5, VirB11, and VirB12 in serum were determined by ELISA. Data are presented as the A₄₅₀ of a 1:16,000 dilution of serum. Each bar indicates the average ± standard deviation for three goats per infected group assayed in triplicate. The uninfected group contains 12 goats. The horizontal line in each graph represents the background reactivity of uninfected goats. Asterisks indicate statistically significant differences between groups of infected and naïve goats, determined by Student's t test. A P value of <0.05 was considered significant.