Effect of cytochalasin B and dihydrocytochalasin B on invasiveness of entero-invasive bacteria in HEp-2 cell cultures.

The effect of cytochalasin B (CB) and di-hydrocytochalasin B (H2CB) on the invasiveness of Salmonella typhimurium, Shigella flexneri and Yersinia enterocolotica serotype 0:3 in HEp-2 cell cultures was examined. The intra-cellular and extra-cellular bacteria were identified by a combination of Nomarski interference contrast microscopy and UV incident light microscopy applied on the same light microscope. Pre-treatment of cells with CB and H2CB inhibited the uptake of S. typhimurium and S. flexneri in the HEp-2 cell cultures. The effect was time and dose dependent. On the other hand, the drugs did not influence the invasiveness of Y. enterocolitica. The results indicate that activity of cellular actin micro-filaments is essential for invasiveness of S. typhimurium and S. flexneri.