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PubMed1987

Detection of postvaccination mumps virus antibody by neutralization test, enzyme-linked immunosorbent assay and sensitive hemagglutination inhibition test.

A group of 251 children aged 2-3 years given live attenuated mumps virus vaccine PAVIVAC of Czechoslovak production were tested for antiparotitis antibody levels in pre- and postvaccination sera by neutralization test (NT), enzyme-linked immunosorbent assay (ELISA) and sensitive hemagglutination inhibition test, enhanced by heterologous antibody to human immunoglobulin G (E-HIT). The prevaccination findings were as follows: positive ELISA IgG titres, neutralization antibodies and hemagglutination inhibition antibodies were present in, respectively, 35%, 25.9% and 27.9% of the sera. Postvaccination seroconversions were evaluated in 159 susceptible vaccinees whose prevaccination sera had been negative by all three tests. The lowest seroconversion was detected by NT (74.2%), seroconversions by ELISA and E-HIT were appreciably higher (82.4% and 86.8%, respectively). The seven children showing a seroconversion by E-HIT but not by ELISA had a 4 fold increase of anti-mumps ELISA IgG antibodies as well, but the rise of antibody titres was at a level falling in the range below the positivity criterion for ELISA. The statistically evaluated detection rate for antibodies was significantly higher (significance test "t") by ELISA as compared with neutralization test. However, antibody levels (geometric mean titres) were 8-10 times lower in postvaccination sera than in convalescent sera of 30 children with mumps in all three tests.

Antibodies, Viral↗
PubMed1972

Arbovirus neutralization tests with Peruvian sera in Vero cell cultures.

Selected human sera from Peru, previously examined by the haemagglutination-inhibition (HI) test with a number of arboviruses, were reexamined by neutralization tests carried out in Vero cell cultures. Results confirmed and extended the HI findings, indicating that the antibodies detected were evoked by Eastern equine encephalitis, Mayaro, Venezuelan equine encephalitis, Ilheus, St Louis encephalitis, yellow fever, Caraparu, and Guaroa viruses.

Antibodies↗
PubMed1990

A refined complement-enhanced neutralization test for detecting antibodies to Junin virus.

A refined, complement-enhanced, plaque-reduction neutralization test was developed for measuring neutralizing antibodies against Junin (Argentine hemorrhagic fever) virus. The assay measured neutralizing antibodies after natural as well as vaccine-induced Junin virus infections. Among vaccinated individuals, titers were 2-4-fold higher than those obtained with conventional assays, without loss of specificity. Enhanced sensitivity was achieved by using a standardized complement source (vs human or animal serum) for virus dilution, incubation of virus-serum mixtures at 36 degrees C for 2 h (vs overnight at 4 degrees C) prior to plaque assay, control of age and density of cell monolayers, and variation in overlay conditions.

Analysis of Variance↗
PubMed1976

[Use of the neutralization test for mass population studies].

The authors applied the antibody neutralization test (ANT) for detection of causative agent of intestinal infections in feces of healthy population in Turkmenia. Some part of the material was studied in parallel with the aid of the ANT and by the bacteriological method. As a result of comparison it appeared that in using the ANT causative agents of intestinal infections were revealed much more frequently than by the bacteriological method; in this connection this serological method can be recommended as an auxiliary one for the diagnosis of intestinal infections.

Diagnosis, Differential↗
PubMedDate not supplied

Comparison of indirect immunofluorescence test for measles antibodies with haemagglutination inhibition and plaque neutralization tests.

Indirect Immunofluorescence (IFA), Plaque Reduction Neutralization (PRN) and Haemagglutination Inhibition (HI) tests for measles antibodies were carried out in 197 sera obtained from umbilical cord and vaccinated children. The IFA was also applied to blood samples collected with filter paper. IFA results demonstrated that the test is relatively simple to perform, with good reproducibility for different antigen lots. Good correlation was obtained between IFA, PRN and HI antibody titers. Better correlation was demonstrated with IFA and PRN than with HI and PRN tests. Sensitivity of IFA in detecting antibody was less effective than PRN, however more effective than HI using rhesus monkey red blood cells. PRN antibody titers over 100 were detected by IFA but not by HI (9.7% with negative results). IFA may be of considerable practical use and able to substitute HI in seroepidemiological surveys and to evaluate vaccine efficacy. It also can be simplified by employing filter paper collected samples.

Adult↗
PubMedDate not supplied

[Study of the correlation between neutralization tests and hemagglutination inhibition tests in determinations of mumps virus antibodies].

In order to find out possibilities of wide application of the hemagglutination-inhibition (HI) test for determination of antibody to mumps virus, correlations between neutralization test (NT) and HI test was studied. Antibody to mumps virus was detected by parallel titrations of sera and gamma globulins in HI and NT tests in two experimental series each of which used various modifications of these tests. Statistically significant strong correlation was established between these tests.

Antibodies, Viral↗
PubMed1976

Comparison of a microneutralization test in cell culture and virus neutralization test in embryonated eggs for determining infectious bronchitis virus antibodies.

A microneutralization test (MNT) system utilizing cytopathic effect end points was effective in determing neutralization indexes for infectious bronchitis virus antibodies. The system is reproducible within 1 index unit at the 95% level of probability. Comparison of the MNT to tests in eggs resulted in a positive correlation (B =0.81), which was significant (P greater than 0.01). The quantitative dose-response relationship of the MNT is linear (P greater than 0.005), with the 95% prediction limits fitting between one 10-fold dilution.

Analysis of Variance↗
PubMed1986

Development of a micro-neutralization test for chikungunya virus.

A rapid, micro-scale focus reduction neutralization test for chikungunya virus was developed. In the test, cell monolayers are prepared in a 96-well tissue culture plate and the PAP (peroxidase-antiperoxidase) staining technique is used for detection of foci of chikungunya virus infected cells. This test is suitable for rapid diagnosis and epidemiological studies of the virus.

Antibodies, Viral↗
PubMed1975

The use of frozen cells in the microtitre serum neutralization test for infectious bovine rhinotracheitis.

Some parameters of the microtitre serum neutralization test were examined when using bovine fetal kidney cells derived from stocks stored in liquid nitrogen. In replicate tests with one serum there was no significant difference (p greater than 0.05) between titres calculated on the basis of cytopathic effect when either two or four wells were used per serum dilution. Also, there was no significant difference between titres calculated on the basis of a cell staining method when either two or four wells were used per serum dilution. When titres obtained by the 2-well-cytopathic effect method were compared with those obtained by the 2-well-stain method differences were not significantly different and it was concluded that the latter method using frozen cells constituted a practical and reproducible test. No significant titre variation occurred in cells serially passaged after having been frozen, or in cells derived from five different fetuses. Titres of sera from 41 cattle conformed to a log normal distribution pattern.

Cells, Cultured↗
PubMed1988

The toxin binding inhibition test as a reliable in vitro alternative to the toxin neutralization test in mice for the estimation of tetanus antitoxin in human sera.

A method for the screening of human sera for tetanus antibodies has been developed and evaluated. The toxin binding inhibition test (ToBI-test) is based on inhibition of the binding of tetanus toxin to an antitoxin-coated immunoassay microtitre plate by tetanus antibodies. Serum samples from 191 healthy adults with different vaccination histories have been titrated for tetanus antibodies by the toxin neutralization (TN) test in mice, by toxoid-ELISA and by the ToBI-test. In every respect, the ToBI-test proved to be the best in vitro alternative to the TN-test in mice. Comparisons showed a higher degree of correlation between the ToBI-test and the TN-test than between the toxoid-ELISA and the TN-test. Furthermore, no overestimation of antibody content was seen in titrating low titre sera by the ToBI-test. In contrast, several false positive results were seen when using the toxoid-ELISA. It is concluded that the ToBI-test is a reliable and precise alternative to the TN-test and can be performed under simple laboratory conditions in a short time.

Animals↗
PubMed1988

On the in vitro neutralization test of Clostridium perfringens type A toxin.

Data are presented on the detection in crude animal and human sera of Cl. perfringens phospholipase C (PLC) inhibitor. When the level of Cl. perfringens type A antitoxin is determined in the in vitro toxin neutralization test the inhibitor is found to decrease PLC activity in the test dose of experimental homologous toxin. The extent of decrease accounts for the variation of results obtained in the in vitro and in vivo toxin neutralization tests. The variation may be cancelled out by introducing a corresponding coefficient to calculate the level of alpha-antitoxin. It is suggested that the isolation and investigation of the PLC inhibitor will contribute to the development of preparations for treatment of gas gangrene due to Cl. perfringens type A.

Animals↗
PubMed1986

A sensitive radioimmunoprecipitation assay for the detection of antibody to recombinant human gamma-interferon: comparison to a bioassay neutralization test.

This report describes a specific radioimmunoprecipitation (RIP) assay for the detection of antibodies to recombinant DNA (rDNA) derived human gamma-interferon (rHuIFN-gamma). The assay was shown not to detect antibodies to rHuIFN-alpha, rHuIFN-beta, human lymphotoxin, or E. coli proteins and was reproducible with intraassay and interassay coefficients of variation of 1.6 and 3%, respectively, for the log titer of a high positive control. Comparison of this assay with a standard bioassay for detection of neutralizing antibody (abrogation of the inhibitory effect of rHuIFN-gamma on EMC virus replication in A549 cells) demonstrated that the RIP assay was more sensitive for detection of HuIFN-gamma neutralizing monoclonal antibody. Nonneutralizing monoclonal antibody was detectable in the RIP assay but not in the bioassay neutralization test. Examination of polyclonal antisera (rabbit and monkey) that contained neutralizing antibodies also demonstrated the RIP system to be a more sensitive indicator of the presence of antibodies than the bioassay neutralization test. In preliminary studies of human samples (86 patients) from clinical trials using an assay precipitation system capable of detecting antibody of the IgG, IgM, IgA, and IgE classes, no antibody to rHuIFN-gamma was observed. These patients were also found negative for neutralizing antibody to rHuIFN-gamma.

Antibodies↗
PubMedDate not supplied

Cell-culture virus-neutralization test and enzyme-linked immunosorbent assay for evaluation of immunity in chickens against fowlpox.

Two serological tests--the virus-neutralization (VN) test in chicken embryo fibroblasts (CEF) using a cell-culture-adapted virus, and the enzyme-linked immunosorbent assay (ELISA)--were used for evaluating the immune response in chickens against fowlpox virus. The VN test was conducted in 96-well tissue-culture plates using a fowlpox virus that was adapted to induce cytopathic effects (CPE) in CEF in 48 hr. The ELISA was carried out with an antigen prepared by precipitation of a cell-culture-propagated virus suspension with ammonium sulfate and concentration by centrifugation. A 0.1 M acetate buffer, pH 5, was used as the sensitizing solution for maximum specific binding of the antigen to the microplate plastic well. No antibodies were detected by the VN test in 228 serum samples taken from chickens at irregular intervals between 1 and 39 weeks of age, even though the birds were vaccinated against fowlpox at 13 weeks of age. However, in sera collected 4 weeks after a sample of laying hens was challenged with fowlpox virus, VN titers of 1/10 to 1/40 were detectable. On the other hand, significant antibody reactions were detected by the ELISA on sera from chickens during the growing period, following vaccination and challenge. Although no maternal antibodies were found at 1 week of age, a continuous increase in the mean ELISA titers to fowlpox was demonstrated during the entire experimental period. This study showed that the ELISA was considerably more sensitive and practical than the VN test.

Animals↗
PubMed1977

[Methods of using the antibody neutralization test in intestinal coli-infections].

Specificity and sensitivity of the antibody neutralization test intended for detection of the O-antigen of enteropathogenic escherichia were checked under experimental conditions. Only 3 strains of the Klebsiella genus proved to neutralize the antibodies to the enteropathogenic escherichia of the serological group O20:K84. In the rest of the cases a positive result was obtained only in homologous combinations. In comparative study of the microbial cultures of the infected feces on hard nutrient media by means of bacteriological and serological methods the latter was found to be more sensitive, capable of detecting the homologous O-antigen with the bacterial concentration of not less than 5-10(5) microbial cells per 1 ml.

Antigens, Bacterial↗
PubMed1978

A new microplate neutralization test for typing of herpes simplex virus.

A microplate serum neutralization test for estimation of complement-requiring neutralizing (CRN) antibody was established as the first step for simplification of typing of herpes simplex virus (HSV). When guinea pigs were immunized with type 2 HSV, the late sera could mostly differentiate the types of HSV better than hyperimmune rabbit sera, the CRN titer against the heterologous type 1 HSV being much lower than the homologous titer. Sera of guinea pigs immunized with type 1 HSV showed about the same level of cross reaction against type 2 HSV as did rabbit antisera. Guinea pig sera having minimal levels of cross reaction were selected, and their high dilution (1:160) and complement were added to serial 10-fold dilutions of virus in the microplate titration of virus infectivity. Selective reduction of virus titer by either antiserum could determine the type of HSV. No equivocal intermediate case was found among a number of stock strains including many fresh isolates. The typing result coincided with that determined by a modification of Yang et al's method based on virus titers obtained with Vero and primary chick embryo cells. The typing based on plaquing in chick embryo cells sometimes failed to identify type 1 HSV.

Animals↗
PubMed1975

[Antibody neutralization test in brucellosis].

The authors present the results of study of the antibody neutralization test in brucellosis with the use of erythrocytes sensitized with lipopolysaccharide. This test was shown to be highly specific and sensitive in detection of brucellae and brucellosis antigen in pathological material, food and objects of external environment.

Animals↗
PubMed1975

Antigenic relationships of group A arboviruses by plaque reduction neutralization testing.

Antigenic relationships of 20 group A arboviruses were assessed by the plaque reduction neutralization test, using highly specific hyperimmune mouse ascitic fluids and antisera. The existence of three complexes of group A viruses was verified. With rare exceptions, heterologous neutralization reactions were observed only among viruses in the same complex; however there were at least one or two immune reagents in each complex which were broadly cross-reactive within that complex.

Animals↗