Protease activity has been demonstrated in culture supernatants of Clostridium tetani at various stages of fermentation. Gel chromatography of the concentrated filtrates revealed the presence of three enzymatically active fractions eluting at separate positions off the column. The smallest protease was found to “nick” the single chain intracellular tetanus toxin, producing the extracellular, tw...

The initial steps in the interaction of diphtheria toxin with HeLa cells were studied. It was demonstrated that lethal doses of toxin are rapidly adsorbed to the cell. The kinetics of uptake, as measured by lethality, indicated that a single toxin molecule is able to cause cell death. Studies on the effect of pH on intoxication showed that adsorption of toxin occurred over a wide pH range but w...

Delta-toxin produced by Clostridium perfringens types B and C is a β-pore-forming cytotoxin. Here, using site-directed mutagenesis, we identified the amino acid residues that contribute to delta-toxin oligomerization binding. We replaced Lys-43 Ser-109 located in β-sandwich domain Arg-200 rim domain. Substitution of alanine for caused reductions both cytotoxicity oligomerization. However, excha...

1. Animals immunized with the formalinized filtrates of young toxic cultures of B. botulinus produce an antitoxic serum poor in precipitins. 2. Animals immunized with the formalinized filtrates of old and partly autolyzed toxic cultures produce an antitoxic serum containing precipitins. 3. Animals immunized with toxin-free autolyzed bacteria produce a serum free from antitoxin but rich in speci...

The transgenic expression of a toxin gene or a thymidine kinase gene under the control of cell type-specific promoter/enhancer has been shown to be useful for removing a specific cell population in mice. However, this approach requires extensive analysis of the control elements for gene expression in the preparation of the transgenic constructs, and furthermore, the toxin gene might be expresse...

Monitoring specific secretory immunoglobulin A (IgA) responses in the intestines after mucosal immunization or infection is impeded by the fact that sampling of small intestinal secretions requires invasive methods not feasible for routine diagnostics. Since IgA plasma cells generated after intragastric immunization are known to populate remote mucosal sites as well, secretory IgA responses at ...

background : clostridium perfringens type c strains cause severe necrotizing enteritis in sheep, calves, goats, pigs and humans. beta-toxin is introduced to be the essential virulence factor of this microorganism. in the present study, a new method was established for the purification of beta toxin from culture supernatant fluid of c. perfringens type c vaccinal strain. methods : the four steps...

objective: verotoxin is a member of shiga toxin family. this family contains ab protein toxins with an enzymatic (a) and a binding (b) compartment. cells that have receptor (gb3) are sensitive to cytotoxic effects of toxin. it has been shown that various tumor cells have gb3 receptor and are selectively sensitive to apoptotic effect of verotoxin. studies on tumor cell lines and laboratory anima...