The most critical step in the production of diphtheria vaccines is the inactivation of the toxin by formaldehyde. Diphtheria toxoid (DTx) is produced during this inactivation process through partly unknown, chemical modifications of the toxin. Consequently, diphtheria vaccines are difficult to characterise completely and the quality of the toxoids is routinely determined with potency and safety...

Diphtheria toxin has the capacity to block protein synthesis in cultured mammalian cells, and thus causing cell death. This capacity of diphtheria toxin was utilized for in-vitro neutralization test to determine antibody titer, using Vero cells, which have been found to be susceptible to diphtheria toxin. In the present study, a Vero cell assay was standardized and validated for potency estimat...

Diphtheria antitoxin (DAT) has been the cornerstone of the treatment of Corynebacterium diphtheriae infection for more than 100 years. Although the global incidence of diphtheria has declined steadily over the last quarter of the 20th century, the disease remains endemic in many parts of the world, and significant outbreaks still occur. DAT is an equine polyclonal antibody that is not commercia...

A DNA transfection method by laser microbeam pricking has been recently reported (Kurata, S. et al. Exp. Cell Res. 162, 372 (1986]. The volume of external fluid transferred into the cell by the method was determined through the injection of diphtheria toxin fragment A (Yamaizumi, M. et al. Cell 15, 245 (1978]. Using these results and the results on laser DNA transfection efficiency (Kurata, S. ...

Diphtheria toxin remains one of the most successfully studied of the bacterial protein toxins. A detailed understanding of the structure function relationships of the toxin and the role of each domain in the intoxication process is well understood. This understanding has led to the development of diphtheria toxin-related fusion protein toxins which are targeted toward specific cell surface rece...

Diphtheria Toxin (DT) was the first investigated bacterial protein toxin. As one of the most extensively studied bacterial protein toxins, it has served as a model system for the analysis of other protein toxins (Pappenheimer, 1977). As reviewed by Pappenheimer, Loeffler identified Corynebacterium diphtheriae as the causative agent of diphtheria in 1884, and the toxin was first described in the...

Purified diphtheria toxin was administered i.v. to 50 patients with advanced solid tumors. The doses of toxin varied according to the different immunological status of the patients against diphtheria. The prominent toxic effects of the treatment were transient peripheral neuropathy observed in two nonimmune patients and fever (37-41 degrees) which occurred in all immune patients with cell-media...

Immunotoxins comprised of a monoclonal antibody covalently coupled to recombinant ricin A chain or to a binding-defective form of diphtheria toxin were compared with respect to their rates of protein synthesis inhibition and efficiencies of killing target cells. Protein synthesis inhibition rates were established by measuring the incorporation of L-[14C]leucine in toxin-treated cells relative t...

Sir: Phenomycin, a basic polypeptide antibiotic, exhibits significant inhibition of Ehrlich carcinoma, sarcoma 180, and adenocarcinoma 755 in mice but has no antimicrobial activity1'2). The mechanism of action of phenomycin has been studied3). The antibiotic inhibits protein synthesis to a significant extent in mammalian ribosomal systems, but much less in bacterial systems. The selective toxic...

The intact diphtheria toxin molecule, a single polypeptide chain of about 62,000 daltons, has no enzymic activity. However, the transfer in uifro of ADP-ribose from NAD to aminoacyltrensferase II can be catalyzed by any of several fragments of toxin. The smallest active fragment (A, 24,000 daltons) is normally connected to the remainder of the molecule (B, 38,000 daltons) by a peptide bond and ...