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PubMed1975

The use of the haemagglutination-inhibition test for detecting antibodies to type SAT 2 foot-and-mouth disease viruses in cattle sera.

Two strains of type SAT 2-foot-and-mouth disease virus which gave high titres of haemagglutinin activity reacted type-specifically in direct haemagglutination-inhibition tests with reference, bovine convalescent antisera. Comparisons of the haemagglutination-inhibition and the serum neutralization tests using cattle sera showed that both were equally specific and sensitive for detecting virus antibody.

Animals↗

PubMed1987

[The mouse paw edema test for titrating Shigella toxin and antitoxin and for determining the safety of the anatoxin].

The method for the titration of Shigella dysenteriae I neurotoxin, toxoid prepared from this toxin and different antitoxic preparations in the mouse paw edema test has been developed. The quantitative determination of antitoxin is based on the neutralization test. The conditions of titration (the dilutions of the neurotoxin and the neutralization doses of the antitoxin), as well as criteria for the evaluation of the positive or negative results, have been established.

Animals↗

PubMed1999

Multicenter evaluation of a new rapid automated human immunodeficiency virus antigen detection assay.

Although human immunodeficiency virus (HIV) antigen assays are of limited value for monitoring antiretroviral therapy, they play an important role for confirmatory testing of fourth generation HIV screening enzyme immunoassay (EIA) reactive samples. In a multicenter study, a new automated rapid p24 antigen assay, Elecsys HIV Ag (Roche Diagnostics Boehringer Mannheim GmbH, Penzberg, Germany), was compared to FDA licensed tests (Abbott HIV-1 Ag monoclonal and Coulter HIV-1 p24 antigen assay). In the evaluation 27 seroconversion panels were included, sera from the acute phase of infection, single and follow-up samples from HIV antibody positive patients, dilution series of HIV antigen positive standards, sera and cell culture supernatants infected with different HIV-1 subtypes (A-H, and O) HIV-2 and recombinant HIV-1 (gag/env) isolates. To challenge the specificity of the new assay, 2565 unselected blood donors, sera from pregnant women, dialysis and hospitalized patients and 407 potentially cross-reactive samples were investigated. Acute HIV infection was detected in three to eight seroconversion panels earlier with Elecsys HIV Ag than with the alternative assays. Higher numbers of serum samples from HIV infected patients tested positive by Elecsys HIV Ag than with the comparative assays. All HIV-1 subtypes and HIV-2 isolates were recognized with Elecsys HIV Ag. Abbott HIV-1 Ag monoclonal and Coulter HIV-1 p24 antigen assay showed a variable sensitivity for the different HIV-1 subtypes. The specificity of Elecsys HIV Ag and Coulter HIV-1 p24 antigen assay were 99.8 and 99.93%, respectively. All the eight sera that were false reactive by Elecsys HIV Ag were tested negative with the Elecsys HIV Ag Neutralization Test. In conclusion, Elecsys HIV Ag was more sensitive than the alternative assays and showed a high specificity in combination with the neutralization assay. The very short incubation time of 18 min and the fully automated procedure of Elecsys HIV Ag which permits direct testing from the primary patient blood collection tube, represent a major improvement for routine laboratory diagnosis in comparison to the alternative assays.

Antibodies, Monoclonal↗

PubMedDate not supplied

Investigations concerning the possibility to replace the Schick test by the passive hemagglutination reaction for evaluating the diphtheria immunity level in population.

The evaluation of Schick test results as compared to the results obtained by determination of diphtheria antitoxin concentration in blood using the neutralizing test on rabbit--Jensen on the one hand and to those obtained by the passive hemagglutination reaction on the other has revealed some discrepancies against the two tests: 7.09% (4.08% pseudo-protected, 3.01 pseudo-susceptible) as against TN-Jensen and 8.6% (5.59% pseudo-protected and 3.01% pseudo-susceptible) as against the passive hemagglutination reaction results. The reported discrepancies were due to the fact that the results of Schick test did not correlate perfectly with the amount of circulating antitoxin, the diphtheria immunity level was wrongly indicated by the Schick test. The passive hemagglutination reaction has proved to be adequate to mass-screening investigations being capable to replace Schick test.

Adolescent↗

PubMed1983

Determination of immunity against tetanus infection by passive haemagglutination assay.

Evaluation of anti-tetanus antibody level in human sera is of primary importance for a prophylaxis of tetanus infection. Many efforts have been made to develop simple, sensitive and reproducible in vitro methods for detecting and quantifying antibodies to tetanus toxin. We have recently developed an HA assay using lyophilized turkey red blood cells (TRBC-HA). In this paper we demonstrated that the TRBC-HA test is more sensitive than the most widely used sheep red blood cell assay (SRBC-HA) and that TRBC-HA assay shows a high correlation with the neutralization test (NT). Furthermore, comparisons of TRBC-HA assay with enzyme-linked immunosorbent assay (ELISA) and counterimmunoelectrophoresis (CIE) indicate that TRBC-HA and ELISA assays detected the same antibody level with a sensitivity up to 400-fold higher than that determined by CIE. However, TRBC-HA also offers many advantages over the ELISA test, because TRBC-HA can be performed in only 40 minutes instead of the 24 hrs. needed for the ELISA, it is less expensive than ELISA and requires no special equipment. Therefore, the overall results suggest that the TRBC-HA is the most appropriate method for rapid and sensitive determination of tetanus antibody levels.

Antibodies↗

PubMed2006

An immunocytometric assay based on dengue infection via DC-SIGN permits rapid measurement of anti-dengue neutralizing antibodies.

Dengue remains a global public health threat and development of a safe and effective vaccine is a principal public health goal. The primary correlate of immunity is thought to be neutralizing antibodies. Currently, the plaque reduction neutralization test (PRNT) is the gold standard measure of dengue neutralizing antibody responses, but this test is limited by time-consuming performance. In addition, some feel that use of viral strains adapted to grow in Vero or BHK cells may not accurately reflect protective responses. A human cell line transfected to express a putative natural dengue receptor, DC-SIGN (CD209), was used to measure antibody-mediated dengue neutralization. Using neutralizing monoclonal antibodies, immune sera, and laboratory adapted dengue viruses, serotype-specific neutralizing activity was demonstrated similar to that seen in the Vero PRNT. Importantly, serotype-specific neutralizing activity against recently isolated dengue strains with less heterotypic cross-neutralization than laboratory adapted viruses was also demonstrated.

Animals↗

PubMed1986

Use of microplate cell culture and enzyme immunoassay in titration of serum neutralizing antibody against Hochi strain of serotype 4 human rotavirus.

The tube neutralization test read by enzyme immunoassay developed by Wyatt et al. (1983) for serotype determination of human rotavirus was modified so as to use stationary cultures of MA104 cells in a microtiter plate instead of roller tube cultures. Sera obtained from different age groups were titrated for neutralizing antibody against serotype 4 human rotavirus Hochi strain by this test and the results were compared with those obtained by the plaque neutralization test. There was a good correlation between the titers obtained by the two tests and the age distribution pattern of serotype 4 neutralizing antibody was similar to those of serotype 1 and 3 antibodies previously reported.

Antibodies, Viral↗

PubMed1978

Agar-gel immunodiffusion assay for pseudorabies virus antibody.

Soluble antigen prepared from pseudorabies virus-infected embryonic pig kidney cells was used to demonstrate the presence of pseudorabies virus antibodies in sera taken from naturally and experimentally infected swine. Antibody could be detected by agar-gel immunodiffusion as early as 14 days postexposure and was demonstrable at least 3 months after experimental infection (the longest period tested). The reliability of the agar-gel immunodiffusion test was comparable to that of the microtitration serum-virus neutralization test commonly used in diagnostic laboratories. One advantage of the agar-gel immunodiffusion test was that severely hemolyzed and cytotoxic serum samples could be tested with confidence. The test is simple, rapid, and inexpensive and could be easily adopted by diagnostic laboratories that receive requests for pseudorabies virus antibody determinations in swine sera.

Animals↗

PubMed1981

Sensitive hemagglutination inhibition test for mumps antibody.

Incorporation of heterologous immunoglobulin against human immunoglobulin G into the mumps HI tests provided a highly sensitive and specific way of measuring mumps antibody in human sera. The sensitivity of this enhanced mumps HI test compared favorably with that of an anti-immunoglobulin-enhanced virus plaque neutralization test, but the HI test required considerably less time and effort to perform.

Animals↗

PubMed1987

Antibody response to enteric adenovirus types 40 and 41 in sera from people in various age groups.

A total of 322 single and paired serum samples from children (newborn to 10 years old), young adults (18 to 20 years old), pregnant women and their cord serum samples, and elderly people (more than 70 years old) was tested for antibodies to enteric adenovirus types 40 and 41 by neutralization test. Serum samples were also tested for antibody to the common antigen of adenovirus by enzyme immunoassay. The incidence of antibodies rose gradually through childhood. Antibodies were found in 20% of children between 1 and 6 months old and in 50% of those 37 to 48 months old. Of serum samples from young adults, 48% had antibodies. Antibodies were found in 10% of serum samples from the aged. Of patients with acute gastroenteritis, 19% showed a significant rise in antibody to adenovirus type 40 or 41 or both, and 42% of the same serum samples had a significant rise in antibody to rotavirus by enzyme immunoassay. None of the serum samples tested was negative to adenovirus common antigen.

Acute Disease↗

PubMed1979

Comparisons of some bluetongue virus isolates by plaque neutralization and relatedness tests.

Seven North American bluetongue virus isolates, cloned by plaquing, and sera to five of them were reacted in a plaque neutralization test. Using a paired controls system, each virus-serum reaction was studied in terms of the regression of percent neutralization on log serum dilution. Antigen-antibody interaction terms in the analysis of effective dose estimates were used to assess the relatedness of the virus isolates. The degree of cross reactivity formed a spectrum from virtually no evidence of unrelatedness to clear antigenic differences.

Antigens, Viral↗

PubMed1975

Chrysanthemum pollinosis in Japan.

Using the scratch test with self-made chrysanthemum pollen extract of 32,700 PNU/ml, a positive response was elicited in 60 of 316 patients (18.9%) with allergic rhinitis and bronchial asthma, and was positive in 42.5% adults with allergic rhinitis. On the other hand a 4.7% positive response was obtained in 84 non-allergic subjects. With the intracutaneous test, a threshold value was determined in 7 cases with 0.327 PNU/ml; 12 with 3.27 PNU/ml; 8 with 32.7 PNU/ml; and 8 with 327 PNU/ml, as opposed to one positive in 84 controls with 327 PNU/ml (1.3%). P-K tests were successfully done in 15 out of 16 cases. Furthermore, the results of in vitro neutralization tests using chrysanthemum and other compositae pollen extracts indicated the absence of sharing antigenic determinants between them. Provocation tests were conducted in 4 cases of allergic rhinitis and 3 cases of bronchial asthma with positive response in all the patients. From these results it was found that chrysanthemim pollinosis indeed exists in Japan, particularly in the mountainous districts.

Adolescent↗

PubMed1980

[Direct solid-phase radioimmunoassay for the detection of Aujeszky's disease antibodies (author's transl)].

A direct solid-phase radioimmunoassay (dRIA) was developed in order to demonstrate antibodies against Aujeszky's disease virus (ADV) in sera obtained from pigs and rabbits. In the presence of guinea-pig complement the above test is 160-fold to 1500-fold more sensitive than the neutralization test (NT) and 320-fold to 150 000-fold more sensitive than NT without complement. By means of dRIA ADV antibodies could be detected in swine sera obtained from an ADV-infected farm, which were found to be negative in the complement assisted NT. It is possible to test a single dilution of unknown serum by dRIA by comparing same with a standard curve and to make a statement regarding its ADV--specific binding capacity to 125I-labelled ADV antigen. The advantages of dRIA in comparison to the indirect RIA and the advantages and disadvantages with regard to ELISA were discussed.

Animals↗

PubMed1987

[Dependence of the specific activity of an immunoglobulin against tick-borne encephalitis on the degree of its fragmentation].

Immunoglobulin preparations against tick-borne encephalitis with the increasing content of Fab-fragments (from 16% to 45%) have been experimentally obtained. As revealed by testing these samples in vivo for specific activity (in the biological neutralization test), the preparations containing 16% of Fab-fragments show no perceptible decrease of specific activity; its sharp decrease (2-16 times) can be observed in preparations with a high degree of fragmentation (the content of Fab-fragments being equal to 30-45%).

Animals↗

PubMed2001

Use of bacterially expressed EBNA-1 protein cloned from a nasopharyngeal carcinoma (NPC) biopsy as a screening test for NPC patients.

EBV serological tests have been used for many years as accessory diagnostic predictors of nasopharyngeal carcinoma (NPC). To increase the sensitivity and specificity of the NPC detection rate, a novel enzyme-linked immunosorbent assay (ELISA) was established using a bacterially-expressed GST-EBNA-1 protein, containing the EBNA-1 sequence cloned from an NPC patient. Serum samples were collected from age- and gender-matched patients with NPC, community control subjects and hospital control patients and tested using this ELISA. The positivity rates were 78.7% (247/314) in NPC, 11.5% (28/244) in hospital controls and 3.8% (10/263) in the community control group. These serum samples were also tested for IgA anti-VCA antibodies and their ability to neutralize EBV DNase and the sensitivities of the anti-VCA antibody and DNase-neutralization tests also were analyzed. The optimum combination is VCA plus EBNA-1, which can identify 92.5% (287/310) of NPC patients, and shows a specificity of 92.7% (242/261) for normal individuals.

Antibodies, Viral↗

PubMed1990

Methods for screening the naturally acquired and vaccine-induced immunity to the measles virus.

Since the measles, mumps and rubella (MMR) vaccine was introduced into Sweden in 1982, a yearly evaluation of the immunity patterns and sero-conversion rates in 12-year-old children has been carried out. Since 1977, about half of the pre-school children have been vaccinated against measles. This study includes two study groups. (1) 145 selected pre- and post-vaccination samples tested by the haemolysis-in-gel (HIG) technique and the neutralization test (NT). The selection was made from 1298 12-year-old schoolchildren in 1986 and 1987, whose pre-vaccination sera had shown negative or borderline reactions to the HIG technique. (2) Consecutive pre- and post-vaccination samples obtained from 190 vaccinees in 1988 and 1989. These samples were studied by an enzyme-linked, immunosorbent assay (ELISA) and compared to the NT. The NT and the HIG tests yielded congruent results in early post-vaccination sera from children susceptible to measles prior to vaccination. In late post-vaccination samples, the NT and the HIG tests were discordant, up to 25% of the NT-positive samples being negative by the HIG technique. In no instance did the ELISA produce discrepant results, compared with those of the NT. With both this assays significantly lower antibody levels were detected in late post-vaccination sera (8-11 years) compared to early post-vaccination samples (P less than 0.001) or to sera obtained after natural infection.

Antibodies, Viral↗

PubMed1982

Cytotonic enterotoxin from Aeromonas hydrophila.

Aeromonas hydrophila produces two hemolysins and an enterotoxin during growth. Enterotoxin, separated from the hemolysins, gave positive reactions in the rabbit intestinal loop test, the rabbit skin test and the adrenal Y1 cell test. Neutralization experiments in the rabbit loop, rabbit skin and Y1 cell tests failed to demonstrate any immunological relationship between Aeromonas enterotoxin and cholera toxin or Escherichia coli heat-labile enterotoxin. Prior incubation of Aeromonas enterotoxin with gangliosides did not inhibit the positive test results in these systems. A co-agglutination test with antiserum to purified cholera toxin was negative for Aeromonas enterotoxin, which therefore seems to be immunologically distinct from cholera toxin. The Aeromonas enterotoxin induced steroid secretion in adrenal Y1 cells and increased the intracellular cyclic adenosine monophosphate (cAMP) content of Y1 cells as well as of rabbit intestinal epithelial cells. It thus seems to act via the adenylate cyclase-cAMP pathway and should be classified as a cytotonic enterotoxin according to the classification of Keusch and Donta (1975).

Adenylyl Cyclases↗

PubMedDate not supplied

[Selection of antigenic variants of the influenza virus on the cells of different hosts].

Antigenic differences were found in influenza B virus variants isolated and propagated in different systems: chick embryos (E variants) and MDCK cell culture (M variants). The antigenic differences in M and E variants were detected in HI tests with polyclonal mouse sera and monoclonal antibodies as well as in biological neutralization tests in chick embryos and MDCK cell culture, and confirmed when M and E variants were used as antigens for antibody detection in human sera. By protein mobility in PAGE, M and E variants did not differ from each other and were also identical with the reference B/Victoria/87 strain.

Animals↗