FIG 7.

The serum bactericidal activity of immune serum from AuNP-protein-vaccinated mice is antigen dependent. EHEC strain 86-24 (1 × 10⁷ CFU) was incubated with 10% active, inactive, and inactive plus exogenous complement source. Bacteria were incubated in the presence of serum using 10% serum for 1 h at 37°C. (A) Viable CFU counts were determined by plating on LB agar plates. Bacterial killing was normalized using bacteria surviving after exposure to adjuvant-only serum. Data are expressed as means ± SEM of results from two independent experiments using sera from n = 8 mice per group. Significant differences were determined via one-way ANOVA followed by Tukey’s post hoc test (*, P < 0.05; **, P < 0.001; ***, P < 0.0001). (B) LIVE/DEAD BacLight assay using SYTO9 to stain live bacteria (cyan) and propidium iodide to stain dead bacteria (red). EHEC strain 86-24 (1 × 10⁷ CFU) was incubated in the presence of AuNP-immune and naive serum for 1 h at 37°C prior to staining.