Where is the gene for diphtheria toxin production?
Diphtheria toxin (DT) is an extracellular protein of Corynebacterium diphtheriae that inhibits protein synthesis and kills susceptible cells. The gene that encodes DT (tox) is present in some corynephages, and DT is only produced by C. diphtheriae isolates that harbor tox+ phages.
How does diphtheria toxin inhibit translation?
Diphtheria toxin kills cells by inhibiting eukaryotic protein synthesis, and its mechanism of action has been extensively characterized. This potent toxin inactivates elongation factor (EF-2) required for protein synthesis (Collier, 1967).
What type of toxin is diphtheria?
Diphtheria toxin is a single polypeptide chain of 535 amino acids consisting of two subunits linked by disulfide bridges, known as an A-B toxin. Binding to the cell surface of the B subunit (the less stable of the two subunits) allows the A subunit (the more stable part of the protein) to penetrate the host cell.
What factor is required for the expression of diphtheria toxin?
The structural gene for diphtheria toxin, tox, is carried by a family of closely related corynebacteriophages of which the β-phage is the most extensively studied (Fig. 32-2). The regulation of diphtheria tox expression is mediated by an iron-activated repressor, DtxR, which is encoded on the C diphtheriae genome.
How is diphtheria toxin formed?
Diphtheria toxin is synthesized by toxigenic strains of Corynebacterium diphtheriae in precursor form and following cleavage of its 25 amino acid signal sequence, it is released into the culture medium as a 535 amino acid single chain protein [2,3,4].
Why is anti diphtheria toxin administered?
Morbidity and mortality due to diphtheria are greatly reduced by prompt administration of antibodies to neutralize toxin and prevent further tissue damage, in conjunction with antibiotics to eliminate C. diphtheriae and stop toxin production.
How does diphtheria toxin interfere with host cell metabolism?
Diphtheria exotoxin, produced by Corynebacterium diphtheriae (inf). This toxin interferes with host cell protein synthesis by catalyzing the ADP-ribosylation of host cell elongation factor 2 (EF-2), necessary in order for tRNA to insert new amino acids into the growing protein chain. This results in cell death.
Is diphtheria toxin heat labile or heat stable?
diphtheriae contained a potent heat-labile toxic protein called diphtheria toxin (DT).
What is the pathophysiology of diphtheria?
Diphtheria is an acute, communicable disease caused by Corynebacterium diphtheriae. The disease is generally characterized by local growth of the bacterium in the pharynx with pseudomembrane formation or, less commonly, in the stomach or lungs; systemic dissemination of toxin then invokes lesions in distant organs.
What receptor does diphtheria toxin bind?
Diphtheria toxin (DT) binds to the epidermal growth factor (EGF)-like domain of human membrane-anchored heparin-binding EGF-like growth factor (proHB-EGF), the human DT receptor (DTR).
What does the diphtheria toxin do?
Diphtheria toxin (DT) is an extracellular protein of Corynebacterium diphtheriae that inhibits protein synthesis and kills susceptible cells.
How do you administer anti diphtheria serum?
The antitoxin dose should be mixed in 250 –500 mL of normal saline and administered slowly over 2 – 4 hours, closely monitoring for anaphylaxis. The antitoxin may be given IM in mild or moderate cases.