FIG. 5.

Survival and replication in J774A.1 macrophages of B. abortus virB deletion mutants. Each deletion mutant was complemented with a pVP derivative carrying the corresponding virB gene under the control of the virB operon promoter. In each graph, the solid line represents CFU of B. abortus 2308; the dashed line represents CFU of the ΔvirB mutant indicated in the upper-right corner of each graph; and the dotted line represents CFU of each deletion mutant complemented with a pVP derivative expressing the corresponding virB gene from the virB promoter. Introduction of the empty pVP plasmid had no effect on intracellular survival of any of the deletion mutants (data not shown). Data presented are averages of results from three experiments with three wells per strain. Error bars represent standard errors of the means. Asterisks denote significant differences (P < 0.05) between numbers of CFU of the mutant and of its complemented strain, determined by Student's t test.