Fig 5.

In vitro neutralization activity of anti-TcdB svFv antibodies (1 µg/mL) on cell rounding induced by native TcdB (10 µg/mL) from C. difficile RT017 on Vero cells. (A) Microscopic cell morphology of Vero cells co-treated with native TcdB, and specific anti-TcdB svFv antibodies for 24 h at 37°C in comparison with untreated Vero cells. Light microscopy (400x magnification), scale bar = 100 µm. (B) The percentage of inhibition of cell rounding in Vero cells treated with anti-TcdB svFv antibodies for 24 and 48 h at 37°C in comparison with untreated cells. The number of round cells were normalized to 100% cytotoxicity for TcdB. Data shown are means ± SD of three independent experiments. A P value of <0.05 was considered as significant (*P < 0.05; **P < 0.01, ***P < 0.001, ****P < 0.0001) by unpaired Student’s t test and one-way ANOVA statistical analysis.