FIG. 4.

In vitro analysis of adhesive functions of different strains of B. bronchiseptica. HEp-2 cells infected with RB50, RB63, RB54, or RBX9 at an MOI of 10, 20, 100, 200, 400, or 500 were washed, and the bacteria adhering to 30 representative epithelial cells were counted and averaged after staining with Giemsa stain. The asterisk represents significantly different attachment levels between RB50 and RB63 with a P value of ≤0.0002. Error bars represent the standard error from the mean. Bordetella strains used for this assay were the wild-type strain RB50 (open squares), Fim⁻ strain RB63 (open diamonds), FHA⁻ strain RBX9 (open triangles), and constitutively Bvg⁻ strain RB54 (open circle).