HvgA promotes specific hyper-adhesion to epithelial and endothelial cells. (a and b) Comparison of the adhesive properties of ST-17 and non–ST-17 GBS strains. Cells were cultured for 1 h with bacteria, washed three times, and lysed, and CFUs were enumerated after plating on TH agar plates. Values are expressed as the percentage of adhesion relative to the inoculum. (c and d) Adhesion of GBS BM110 WT (ST-17) and ΔhvgA mutant to various cell lines, primary choroid plexus epithelial cells, and brain microvessel endothelial cells. Adhesion assays were conducted as described in a and b. Streptococci were labeled with a pAb-GBS (green), nuclei were labeled with Dapi (blue) and ZO1 with an anti-ZO1 antibody, and F-actin was labeled with phalloidin (red). Bar, 20 µm. Throughout this figure, results are representative of at least three independent experiments performed in triplicate. Error bars represent the SD. Asterisks indicate significant differences relative to BM110 WT or GBS ST-17 strains, as assessed by the Mann-Whitney test (*, P < 0.05; **, P < 0.01; ***, P < 0.001). NS, a nonsignificant difference.