Use of specific Bordetella pertussis antibodies in immunoenzyme analysis for detecting the pertussis antigen

The competitive EIA technique with the use of peroxidase-labeled B. pertussis antigen has been developed. The data obtained in our investigations suggest the possibility of using this technique for the detection of B. pertussis antigen in faucial smears obtained from patients.     

Development of a method of obtaining peroxidase conjugates with anti-immunoglobulin for immunoenzyme analysis

The results of the successive stages of preparing peroxidase-labeled anti-immunoglobulins are presented. The schedules for the immunization of animals have been worked out with a view to prepare antisera to human gamma globulin and, subsequently, to isolate antibodies from them by different methods. The preparations obtained with the use of immunosorbent have proved to possess the highest serological activity. As the result of these investigations, a new method of binding, a modification of the glutaraldehyde method, has been proposed. The conjugates obtained by the proposed method are characterized by high serological activity, stability and good reproducibility.     

Choice of the method for isolating conjugates of staphylococcal protein A with peroxidase for immunoenzyme analysis

An attempt to obtain the preparations of peroxidase-labeled staphylococcal protein A, intended for use in the enzyme immunoassay, by the glutaraldehyde method has failed. The modified periodate method permitting the preparation of active conjugates of staphylococcal protein A with peroxidase has been developed.     

Development of an immunoenzyme method for detecting Francisella tularensis

The conditions permitting the determination of F. tularesis cells by means of the enzyme immunoassay (EIA) in 3-5 hours have been established. Ways for enhancing the reliability of results obtained in the assay of the least possible amount of the test material have been proposed. The sensitivity and specificity of the rapid EIA technique permitting the determination of F. tularensis cells at a concentration of 20 000 cells/ml in the presence of other bacterial cells in 100-fold excess have been shown.     

Modified plasmid isolation method for Clostridium perfringens and Clostridium absonum

A rapid plasmid isolation procedure for Clostridium perfringens and C. absonum is described. The ratio of culture volume to lysis buffer volume was found to be crucial for efficient plasmid isolation. The method can be scaled up, without difficulty, for large-scale plasmid preparation.     

Modified plasmid isolation method for Clostridium perfringens and Clostridium absonum.

A rapid plasmid isolation procedure for Clostridium perfringens and C. absonum is described. The ratio of culture volume to lysis buffer volume was found to be crucial for efficient plasmid isolation. The method can be scaled up, without difficulty, for large-scale plasmid preparation.     

Membrane filter enumeration method for Clostridium perfringens.

A membrane filter procedure has been developed for the rapid quantitation of C. perfringens in the aquatic environment. Background growth is inhibited by the use of D-cycloserine, polymyxin B sulfate, and incubation at 45 degrees C. Differential characteristics include the fermentation of sucrose, production of acid phosphatase, and the absence of beta-D-glucosidase activity. The medium is prepared as follows (in grams per 100 ml of distilled water): tryptose, 3.0; yeast extract, 2.0; sucrose, 0.5; L-cysteine, 0.1; MgSO4. 7H2O, 0.01; bromocresol purple, 0.004; and agar, 1.5. The ingredients are dissolved, and the pH is adjusted to 7.6. After autoclaving at 121 degrees C for 15 min, the medium is allowed to cool at 50 degrees C, and the following are added per 100 ml: D-cycloserine, 40 mg; polymyxin B sulfate, 2.5 mg; indoxyl-beta-D-glucoside, 60 mg; 2.0 ml of a filter-sterilized 0.5% phenolpthalein diphosphate solution; and 0.2 ml of a filter-sterilized 4.5% FeCl3.6H2O solution. Enumeration of C. perfringens in a water sample is completed within 18 to 24 h. The verification of typical colonies was 93%. The average recovery from peptone-water spore suspensions of five strains was 79%, and that from filter-sterilized seawater suspensions was 90%. The precision of the method was approximately equal to that expected from random error alone. Confirmed recoveries of C. perfringens from water and sewage samples generally were greater than those by the Bonde pour tube method.     

Membrane filter enumeration method for Clostridium perfringens.

A membrane filter procedure has been developed for the rapid quantitation of C. perfringens in the aquatic environment. Background growth is inhibited by the use of D-cycloserine, polymyxin B sulfate, and incubation at 45 degrees C. Differential characteristics include the fermentation of sucrose, production of acid phosphatase, and the absence of beta-D-glucosidase activity. The medium is prepared as follows (in grams per 100 ml of distilled water): tryptose, 3.0; yeast extract, 2.0; sucrose, 0.5; L-cysteine, 0.1; MgSO4. 7H2O, 0.01; bromocresol purple, 0.004; and agar, 1.5. The ingredients are dissolved, and the pH is adjusted to 7.6. After autoclaving at 121 degrees C for 15 min, the medium is allowed to cool at 50 degrees C, and the following are added per 100 ml: D-cycloserine, 40 mg; polymyxin B sulfate, 2.5 mg; indoxyl-beta-D-glucoside, 60 mg; 2.0 ml of a filter-sterilized 0.5% phenolpthalein diphosphate solution; and 0.2 ml of a filter-sterilized 4.5% FeCl3.6H2O solution. Enumeration of C. perfringens in a water sample is completed within 18 to 24 h. The verification of typical colonies was 93%. The average recovery from peptone-water spore suspensions of five strains was 79%, and that from filter-sterilized seawater suspensions was 90%. The precision of the method was approximately equal to that expected from random error alone. Confirmed recoveries of C. perfringens from water and sewage samples generally were greater than those by the Bonde pour tube method.     

Use of Dogs as an Assay for Clostridium perfringens Enterotoxin

Three techniques for using the dog as an assay organism for Clostridium perfringens enterotoxin are described. These are believed to be more convenient than ligated ileal-loop procedures.     

A simple method for the isolation and determination of Clostridium perfringens

Summary A method for the isolation and determination of small numbers of vegetative cells or spores of Clostridium perfringen has been developed based on enrichment under anaerobic conditions in a fluid thioglycollate medium without dextrose, containing 400 g of D-cycloserine/ml at 46°C for 18 h (PEM). It allows virtually complete recovery of vegetative cells of all strains of Clostridium perfringens tested, whereas facultative anaerobes present in food are inhibited. Undamaged Clostridium perfringens spores can also be detected by this procedure. After enrichment, isolation of Clostriduum perfringens is carried out on iron sulphite agar at 46°C for 18 h. Typical black colonies are picked and confirmed by the following tests: neutralization of the -toxin by a specific diagnostic antiserum and absence of indole, motility, and ability to liquify gelatin.     

Use of solid-phase immunoenzyme analysis for the serodiagnosis of pseudotuberculosis

The diagnostic test system based on the solid-phase enzyme immunoassay (EIA) for the detection of antibodies to Yersinia pseudotuberculosis in the sera of patients with the use of Soviet-made preparations and reagents has been developed. The test has been performed in microchambers for immunological reactions, thus making it possible to decrease the consumption of reagents 10-20 times in comparison with the traditional technique with the use of plates. The results of the titration of 42 sera in EIA and in the passive hemagglutination test (PHAT) are indicative of the presence of positive correlation (r = 0.78; p less than 0.05) between antibody titers in EIA and PHAT. A fourfold or greater increase in antibody titers has been determined by means of EIA in 80% of cases and with the use of PHAT in 55% of cases. The minimum diagnostic titer yielded by EIA has been determined: 1:256.     

Electroporation-induced transformation of intact cells of Clostridium perfringens

Electroporation-induced transformation of intact cells of Clostridium perfringens 3624A with plasmids pAMB1 and pHR106 resulted in 3.8 X 10(-5) and 4.2 X 10(-4) transformants per viable cell, respectively. With respect to shuttle plasmid pHR106, these values represent a greater than 100-fold increase in transformation frequency when compared with the values reported with polyethylene glycol-induced L-phase variants.     

Homogeneous immunoenzyme analysis of human immunoglobulin G using horseradish peroxidase

The author studied the steady-state kinetics of cooxidation of 4-aminoantipyrine (AAP) with phenol and its derivatives--alpha-naphthol, o- and m-acetylaminophenols--by horseradish peroxidase and its conjugate with human immunoglobulins IgG (HRP-IgG). When phenol and AAP were used as peroxidase substrates, anti-human IgG antibodies stimulated the HPR-IgG enzyme activity in the presence of excess H2O2. A homogeneous enzyme immunoassay of human IgG was developed on the basis of this stimulating effect. The kinetics of the interactions between immunological reagents was studied. In the presence of 3% polyethylene glycol 6000, a complete antibody-antigen interaction proceeds at 37 degrees for 15-20 min. The sensitivity of the enzyme immunoassay is 350 ng/ml IgG, and the dynamic detection range is 0.35-15.0 mg/ml.     

Improved method for purification of enterotoxin from Clostridium perfringens type A

The purification procedure of Clostridium perfringens type A enterotoxin has been improved. The cell sonic extract was precipitated twice with ammonium sulfate, first 40% saturated to concentrate the enterotoxin and then 15% saturated. The two precipitations were followed by gel filtration on Sephadex G-100. The enterotoxin appeared to be homogeneous on 7% polyacrylamide gel electrophoresis after this three-step purification procedure, with a recovery of 56% and a 12.3-fold purification. The solubility properties at different pH values, temperatures, and ammonium sulfate concentrations are also given as basis for the purification procedure.     

Use of immunoenzyme analysis in the diagnosis of toxoplasmosis

The method for the preparation of antigen for ELISA and the technique of this assay are described. The comparative data obtained in the examination of 50 donors and 95 children suspected to have toxoplasmosis, carried out with the use of immunofluorescence and ELISA, are presented. A good correlation between the results of the both tests has been shown.     

Molecular methods for the analysis of Clostridium perfringens relevant to food hygiene

Clostridium perfringens continues to be a common cause of food-borne disease. It produces an enterotoxin (CPE) which is released upon lysis of the vegetative cell during sporulation in the intestinal tract. Catering premises with insufficient cooling and reheating devices often seem to be the cause of outbreaks of C. perfringens food poisoning. Typing of C. perfringens is of great importance for investigating sources of food poisoning cases and for studying the epidemiology of this microorganism. This report describes the examination of 155 C. perfringens isolates by molecular methods. Isolates were taken from 10 food poisoning outbreaks and cases (n = 34, food and fecal isolates) and from meat and fish pastes (n = 121). Isolates were characterized by plasmid profiling, ribotyping, and/or macrorestriction analysis by pulsed-field gel electrophoresis (PFGE). Results show that all three methods are suitable for classifying C. perfringens isolates below the species level. Ribopatterns and PFGE patterns can be interpreted more easily than plasmid profiling results and can be recommended for contamination studies and epidemiologic investigation of food poisonings associated with C. perfringens.     

Use of an experimental analytical method for equilibrating nutrient broths for Clostridium perfringens type A growth and toxin formation

A successful attempt to use analytico-experimental approach to the evaluation of experimental data for the scientifically based calculation of the composition of complex culture media, intended for growing pathogenic microorganisms, has been made. The method is based on the evaluation of the specific growth-stimulating and toxin-forming activity of the components of a given culture medium, which are determined by the number of cells grown in the variants of the medium with the limited amount of one of its components. The use of the analytico-experimental balancing method makes it possible to develop culture media with the optimal composition ensuring the definite yield of the target product rather quickly and economically by experimenting on the minimal number of variants equal to the number of the components of the medium. The investigation carried out by means of the analytico-experimental method has revealed that on the basis of peptic serum albumin hydrolysate, pancreatic casein hydrolysate and fodder yeast extract, alongside the culture medium described in an earlier work and containing these components in the proportion 4:2:1, two other media, containing the above components in the proportion 2:4:1 and 3:4:2, can be obtained, these media providing the optimal conditions for, respectively, the toxin formation and growth of C. perfringens, type A.