diphtheria toxin


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toxin

 [tok´sin]
a poison, especially a protein or conjugated protein produced by certain animals, higher plants, and pathogenic bacteria. Bacterial toxins characteristically do not cause symptoms until after a period of incubation while the microbes multiply, or (as happens with botulism) the preformed toxin reaches and affects the tissue. Usually only a few toxin-producing agents are introduced into the body, and it is not until there are enough of them to overwhelm the leukocytes and other types of antibodies that symptoms occur. In some cases of food poisoning, symptoms are almost immediate because the toxin is taken directly with the food. Toxins can cause antitoxins to form in the body, thus providing a means for establishing immunity to certain diseases.
bacterial t's toxins produced by bacteria, including exotoxins, endotoxins, enterotoxins, neurotoxins, and toxic enzymes. See also toxin.
botulinal toxin (botulinum toxin) (botulinus toxin) one of seven type-specific, immunologically differentiable exotoxins (types A to G) produced by Clostridium botulinum,neurotoxins usually found in imperfectly canned or preserved foods. They cause botulism by preventing release of acetylcholine by the cholinergic fibers. Type A is one of the most powerful poisons known; it is also used therapeutically by injection to inhibit muscular spasm in the treatment of dystonic disorders such as blepharospasm and strabismus, to treat wrinkles of the upper face, and to reduce anal sphincter pressure to promote healing of chronic anal fissure. Type B is injected in treatment of cervical dystonia. Called also botulin.
cholera toxin an exotoxin produced by Vibrio cholerae; a protein enterotoxin that binds to the membrane of enteric cells and stimulates the adenylate cyclase system, causing the hypersecretion of chloride and bicarbonate ions, resulting in increased fluid secretion and the severe diarrhea characteristic of cholera.
clostridial toxin one elaborated by species of Clostridium, including those causing botulism (botulinus toxin), gas gangrene (gas gangrene toxin), and tetanus (tetanus toxin). In addition, C. difficile produces an exotoxin causing severe intestinal necrosis and C. perfringens produces exotoxins causing gas gangrene, intestinal necrosis, hemolysis, cardiotoxicity, and deoxyribonuclease and hyaluronidase activity, as well as an enterotoxin causing food poisoning.
Dick toxin erythrogenic toxin.
diphtheria toxin a protein exotoxin produced by Corynebacterium diphtheriae that is primarily responsible for the pathogenesis of diphtheria and related infections; it is an enzyme that activates transferase II of the mammalian protein synthesizing system.
diphtheria toxin for Schick test a sterile solution of the diluted, standardized toxic products of Corynebacterium diphtheriae; used as a dermal reactivity indicator in the schick test of immunity to diphtheria.
dysentery toxin any of various exotoxins produced by species of Shigella; the one formed by S. dysenteriae serotype 1 is a potent neurotoxin with hemorrhagic and paralytic properties.
erythrogenic toxin a bacterial toxin from certain strains of Streptococcus pyogenes that produces an erythematous reaction when injected intradermally and is responsible for the rash in scarlet fever.
extracellular toxin exotoxin.
gas gangrene toxin an exotoxin that causes gas gangrene; there are at least 10 types produced by Clostridium perfringens and others produced by C. noriyi and C. septicum.
streptococcal toxin a mixture of exotoxins formed by Streptococcus pyogenes.
tetanus toxin the potent exotoxin produced by Clostridium tetani, consisting of two components, one a neurotoxin (tetanospasmin) and the other a hemolysin (tetanolysin).

Cor·y·ne·bac·te·ri·um diph·the·'ri·ae

a bacterial species that causes diphtheria and produces a powerful exotoxin causing degeneration of various tissues, notably myocardium, in humans and experimental animals, and catalyzing the ADP-ribosylation of elongation factor II; virulent strains of this organism are lysogenic; it is commonly found in membranes in the pharynx, larynx, trachea, and nose in cases of diphtheria; it is also found in apparently healthy pharynx and nose in carriers, and occasionally in the conjunctiva and in superficial wounds; it occasionally infects the nasal passages and wounds of horses; it is the type species of the genus Corynebacterium.

diphtheria toxin

Infectious disease A 62 kD protein responsible for C diphtheriae's cardiotoxic and neurotoxic effects, and mucosal damage. See Corynebacterium diphtheriae, Diphtheria.
References in periodicals archive ?
Gillet, "Solution and membrane-bound chaperone activity of the diphtheria toxin translocation domain towards the catalytic domain," FEBS Journal, vol.
Eisenberg, "Crystal structure of nucleotide-free diphtheria toxin," Biochemistry, vol.
Inhibition of membrane translocation of diphtheria toxin A-fragment by internal disulfide bridges.
"Two known proteins, tetanus toxoid and CRM197, a nontoxic recombinant variant of diphtheria toxin, are commonly used to develop these kinds of vaccines," explained Pantophlet.
They created a hybrid of diphtheria toxin and interleukin-2 that binds exclusively to CD4 cells possessing the receptor and kills them.
Five of the 136 isolates had both A and B subunits of diphtheria toxin (tox), detected by multiplex PCR, all of which appeared to be functional by sequence analysis (7).
Both organisms can produce diphtheria toxin and lead to life-threatening disease that requires urgent treatment with DAT and antibiotics.
The researchers have already fused a variant of diphtheria toxin into the Rad51 gene as a "toxic bomb" and tested it on a variety of cancer cell types, including breast cancer, fibrosarcoma, and cervical cancer cells.
To induce this immune response against a woman's own hormone, scientists developing the vaccine anchored a synthetically produced portion of the hCG molecule to diphtheria toxin, a combination capable of inducing strong antibody reaction against both substances.
The successful implementation of vaccination programs in industrialized and many developing countries indicates that most of these populations have antibodies against the diphtheria toxin. Nonetheless, the geometric mean concentration of IgG against diphtheria toxin in plasma of vaccinated adults who received the last dose of tetanus-diphtheria vaccine in their adolescence is not much over 0.3 IU/mL (6).
During 1999-2005, a total of 30 million doses of three different meningococcal C conjugate vaccines (MenC), with either diphtheria CRM (nontoxic variant of diphtheria toxin) or tetanus toxoid as carrier proteins, have been used in the United Kingdom (UK) for persons aged < 18 years.
Murphy and his colleagues have produced a hybrid protein that is a modified diphtheria toxin. The new protein remains a potent killer of cells, but through protein engineering (see p.

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