FIG. 4.

bvfA is induced intracellularly in response to phagosome acidification. Gene expression was measured by FACS using transcriptional fusions to GFP. The bacteria were recovered from J774 macrophages 3 h postinfection of normal (left) or bafilomycin A (100 nM)-treated (right) macrophages as described previously (5). Expression from the bvfA promoter is shown in pink, pvirB is shown in blue, expression from the empty vector is shown in green, and expression from a constitutive promoter is shown in red.