Figure 1: Electron microscopy. (a) Representative pictures showing CT binding to tumor cells via surface molecules (upper panel). Sustained cellular integrity despite heat inactivation was confirmed (lower panel). Cell proliferation and viability. (b) Tumor cells were seeded in 96-well plates and cultured with increasing CT concentrations (corresponding to 5 * 102, 2.5 * 104, and 2.5 * 106 cfu/mL) for 24 and 48 hours. Thereafter, cell proliferation was estimated by BrdU uptake and quantification on a plate reader at 450 nm according to the manufacturer’s instructions. Percentage of proliferating cells was calculated compared to untreated control (100%). (c) For estimating viability, tumor cells were seeded in 24-well plates and treated with CT as described above. Following the incubation period (24 and 48 hours), the cells were stained with Calcein AM and fluorescence intensity was measured on a plate reader (ex/em 485/535 nm). Cell viability was calculated by setting relative fluorescence intensities of Calcein AM-stained nontreated cells (live control) to 100%. Results show data of three separate experiments each performed in duplicates. Values are given as the mean ± SEM.