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At least 415 records · Page 23Linked to original sources
PubMed1987

A comparison of the indirect haemagglutination test with the toxin neutralization test for the estimation of diphtheria antitoxin in mouse sera.

Serum samples from 42 groups of mice immunized for different immunization periods with various doses of Adsorbed Diphtheria-Tetanus Vaccine, Adsorbed Diphtheria-Tetanus and Pertussis Vaccine and a standard diphtheria toxoid were assayed for their diphtheria antitoxin content by indirect haemagglutination (IHA) and by toxin neutralization (TN) tests. A very good correlation of 0.91 was obtained between the results of the two methods. There was no statistically significant difference between the IHA and the TN titres obtained. Adsorption with sheep red cells and treatment of the sera with 2-mercaptoethanol had no effect on the IHA titres. The minimum level of antitoxin detectable by the IHA test was 0.00039 IU ml-1. IHA proved to be a sensitive, specific and reproducible method which can be used reliably for the assay of diphtheria antitoxin in mouse sera.

Animals↗
PubMed1975

Detection of Clostridium botulinum toxin by local paralysis elicited with intramuscular challenge.

Clostridium botulinum toxin can be identified by a characteristic, acute local paralysis that follows its injection into the gastrocnemius ("calf" muscle) of mice. The local botulism can be elicited with slightly less than one-tenth the toxin amount that is needed to kill mice by the intraperitoneal (i.p.) challenge route. The practical sensitivities of the intramuscular (i.m.) versus i.p. tests are about equal, however, because maximum sample volume injectable i.m. is 0.1 ml as compared to the 0.5-ml range that can be given i.p. i.m. injection of 10 or more mouse i.p. mean lethal doses causes paralysis in about 1 h, and an i.m. injection of about 0.5 i.p. mean lethal doses causes paralysis in 3 to 4 h. Toxin neutralization by homologous type of antitoxin only can be demonstrated with an incubated mixture of toxin and antitoxin. Although not as convenient as the i.p. method for routine use to detect botulinum toxin, the i.m. method has characteristics which could make it a useful supplement to the presently accepted i.p. procedure.

Animals↗
PubMed1977

Radioimmunoassay for the antigenic determinants of cholera toxin and its components.

A radioimmunoassay procedure is described for the detection of cholera toxin and its component polypeptide chains. Cholera toxin, A subunit, B subunit, alpha chain, and gamma chain were iodinated by the chloramine T procedure. Radiolabeling did not significantly alter the polyacrylamide electrophoretic migration patterns of the toxin or its components. Moreover, radiolabeled toxin, B subunit, and alpha chain preparations retained substantial ability to bind to intestinal mucosal homogenates. The minimal amount of antitoxin detectable with radiolabeled toxin was 0.04 antitoxin units/ml. Substitution of radiolabeled B subunit, A subunit, and alpha chain for radiolabeled toxin decreased the sensitivity of the test. Radiolabeled gamma chain did not bind to the antitoxin preparation. Competitive inhibition studies, with titrated anti-choleragen serum and radiolabeled toxin or components, indicated that the minimum concentration of toxin detectable was 7.0 x 10(-8) mumol/ml at a 90% inhibition level. The A subunit and alpha chain preparations inhibited the binding of the radiolabeled B subunit to antitoxin sites. Conversely, B subunit inhibited the binding of radiolabeled A subunit and alpha chain to antitoxin. The gamma chain did not show any reaction with antitoxin or cross-reaction with either whole toxin or its components. These results strongly suggest that the A subunit and the alpha chain contain antigenic determinant(s) that are common to the B subunit. The B subunit (beta chain) and the alpha chain of cholera toxin may therefore contain region(s) of chemical similarity.

Antigens, Bacterial↗
PubMed1979

Protection against experimental cholera by oral or parenteral immunization.

Comparisons were made between the antigenic potency and protective capacity of several cholera toxin derivatives. Rabbits were immunized parenterally with 50 microgram of cholera toxin, A subunit, B subunit, procholeragenoid, or Wyeth glutaraldehyde toxoid 20101. Examination of the antibody response curves revealed that cholera toxin elicited serum antitoxin responses that rose more quickly than in the subunit-immunized animals; however, antitoxin levels were of the same magnitude after 10 weeks. Parenteral immunization with procholeragenoid evoked antibody titers that were similar to the toxin, whereas Wyeth toxoid yielded only one-tenth the level of antitoxin. Oral immunization with procholeragenoid as well as Wyeth toxoid resulted in lower serum antitoxin titers than that achieved with parenteral immunization, despite the oral administration of 10 times the parenteral dose. Analysis of protection against live-cell challenge revealed that parenteral administration of procholeragenoid provided the best protection against fluid accumulation. Oral immunization with procholeragenoid also was very effective, whereas oral immunization with B subunit or Wyeth toxoid resulted in minimal protection. Also, the A subunit provided surprisingly more protection than did cholera toxin.

Administration, Oral↗
PubMed1975

Preparation, measurement and possible use of human antitoxin against Cl. botulinum A, B, and E toxins.

Human antibodies against botulinum toxins A, B, and E have been raised by repeated injections of pentavalent toxoid in a healthy volunteer. The final titer was 3.2 U anti-A, 0.4 U anti-B, and 2.5 U anti-E/ml. In mice, the efficacy of the antitoxin decreases with the time between poisoning and application of the antiserum. The dose recommended for prophylactic purposes in man is 1 ml/kg. In overt poisoning, therapy should be started with higher titer animal serum since in animal experiments high titer sera can stop (although not reverse) the symptoms of overt botulism within an-admittedly not too broad-rnage of time and dosage. Later on, therapy can be continued with human antiserum. An inverse radioimmunassay for botulinum A antitoxin using labeled botulinum toxin and antibody-coated tubes is described. The serum is available upon request from the author.

Animals↗
PubMed1976

The detection of toxin production by Corynebacterium diphtheriae in diagnostic laboratories.

In vitro tests for assessing the toxigenicity of strains of C. diphtheriae using the original agar plate precipitin method of Elek are unreliable. At high concentrations of antitoxin (500-1000 U/ml) multiple non-specific precipitin lines occur making interpretation difficult. Increased specificity was obtained by diluting the antitoxin but this in turn caused a delay in the appearance of toxin-antitoxin lines. Also, the failure of lines to appear on media enriched with unsuitable serum may lead to false-negative results. Final assessment of the toxigenicity of strains of C. diphtheriae can probably only be made reliably by guinea-pig tests.

Animals↗
PubMed1993

The First International Standard for Antitetanus Immunoglobulin, Human; pharmaceutical evaluation and international collaborative study.

The First International Standard (IS) for Antitetanus Immunoglobulin, Human (coded 26/488) was established by the WHO Expert Committee on Biological Standardization in October 1992 on the basis of an extensive pharmaceutical evaluation and an international collaborative study. Fifteen laboratories from 15 countries performed the toxin neutralization assay in vivo in the study. Twelve laboratories also performed an alternative in vitro assay. The new International Standard is a purified human immunoglobulin containing antibodies which are able to neutralize tetanus toxin. This new standard replaces the Second International Standard for Tetanus antitoxin, Equine, for testing of human antitetanus immunoglobulin preparations used clinically as well as for titration of human serum samples for tetanus antitoxin. The new International Standard was assigned a potency of 120 International Units (IU) of Tetanus Antitoxin per ampoule on the basis of its calibration in terms of the International Unit defined by the Second International Standard for Tetanus Antitoxin, Equine by toxin neutralization assay in vivo. The same preparation was also established as the first European Pharmacopoeia Standard for Antitetanus Immunoglobulin, Human by the European Pharmacopoeia Commission, Biological Standardization Programme in March 1993.

Animals↗
PubMed2000

Enhancement of diphtheria toxin potency by replacement of the receptor binding domain with tetanus toxin C-fragment: a potential vector for delivering heterologous proteins to neurons.

This study describes the expression, purification, and characterization of a recombinant fusion toxin, DAB(389)TTC, composed of the catalytic and membrane translocation domains of diphtheria toxin (DAB(389)) linked to the receptor binding fragment of tetanus toxin (C-fragment). As determined by its ability to inhibit cellular protein synthesis in primary neuron cultures, DAB(389)TTC was approximately 1,000-fold more cytotoxic than native diphtheria toxin or the previously described fusion toxin, DAB(389)MSH. The cytotoxic effect of DAB(389)TTC on cultured cells was specific toward neuronal-type cells and was blocked by coincubation of the chimeric toxin with tetanus antitoxin. The toxicity of DAB(389)TTC, like that of diphtheria toxin, was dependent on passage through an acidic compartment and ADP-ribosyltransferase activity of the DAB(389) catalytic fragment. These results suggest that a catalytically inactive form of DAB(389)TTC may be useful as a nonviral vehicle to deliver exogenous proteins to the cytosolic compartment of neurons.

3T3 Cells↗
PubMed1981

Tetanus toxin association with developing neuronal cell cultures. Kinetic parameters and evidence for ganglioside-mediated internalization.

Rat cerebral neurons maintained in monolayer culture accumulate 125I-labeled tetanus toxin. Accumulation is receptor-mediated; i.e. it can be prevented by including unlabeled tetanus toxin, gangliosides, or tetanus antitoxin in the incubation medium but not by including tetanus toxoid, high concentrations of serum, or thyrotropin. Accumulation is time-dependent, reaching a plateau after approximately 3 h when 60% of the added toxin is associated with the cells. It is better at 0 degrees C than at ambient temperature and is significantly higher when 0.25 M sucrose replaces physiological salts in a medium containing 5% serum. Unlabeled tetanus toxin, tetanus antitoxin, and tetanus toxoid do not release the accumulated 125I-labeled tetanus toxin to any significant degree; however, gangliosides (50 micrograms/ml) can release 30% of the accumulated 125I-labeled toxin. Treatment of cells with Triton X-100, under conditions where over 90% of the lipids and 70% of the gangliosides are removed, extracts only 15% of the cell-associated 125I-labeled toxin. Evidence is presented that over 50% of the accumulated toxin is internalized in a cellular compartment which is not in immediate equilibrium with the extracellular environment and which is associated with detergent-insoluble cellular constituents. The tetanus toxin accumulated in this compartment has the same gel electrophoretic pattern as the native toxin and is bioactive. The role of gangliosides as potential shuttle vehicles for tetanus toxin internalization is discussed as are the implications of these data to in vitro studies of the pathogenesis of tetanus-induced neurotoxicity.

Animals↗