Figure 8. GBS ScpB forms protein complexes with fibronectin and attenuates GBS dissemination.

(A) FXIIIA-mediated crosslinking between purified ScpB and fibronectin. ScpB (2 μM) was incubated with fibronectin (1 μM) and FXIIIA (30 μg/mL) in TBS, pH 7.4, 5 mM CaCl₂ buffer at 25°C from 0 to 240 minutes. Aliquots were removed at the indicated times and were separated on SDS-PAGE, followed by Western blotting with either the anti-ScpB (top panel) or anti-fibronectin (bottom panel) antibodies. Controls included ScpB alone, fibronectin (FN) alone, or samples lacking FXIIIA. Arrows indicate the positions of the ScpB, FN, and products of the crosslinking reaction, which are depicted as P1, P2, and P3. A representative blot from 3 independent experiments is shown. (B) WT B6 mice were infected i.p. with 0.5 to 1 × 10⁸ CFU of WT GBS strain COH1, isogenic ScpB-deficient GBS (ΔscpB), or the complemented strain(ΔscpB/pScpB). At 24 hours after infection, bacterial burden was evaluated in blood, peritoneal fluids, spleen, and lungs. Data are shown as medians with boxes representing values from individual mice. *P < 0.05; **P < 0.01, Kruskal-Wallis test with Dunn’s multiple-comparison test.