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PubMed1995

Serum neutralization test for epidemiological studies of salmonid rhabdoviroses in France.

Serological examination is not yet accepted as being a suitable diagnostic method for fish that are asymptomatic virus carriers. Nevertheless, encouraging preliminary results using an end-point serum neutralization test (SNT) in several French trout farm populations have demonstrated an excellent correlation between the SNT and the previously established virus histories of the tested populations. Following the isolation of infectious haematopoietic necrosis virus (IHNV) in France, serological screening of fish for a neutralizing antibody (NAb) to IHN was conducted on a national scale. This survey confirmed the relationship between the serum-neutralizing immune response of the fish and the presence of IHNV in a given trout farm population. Insofar as many trout populations underwent dual rhabdovirus infections with both IHNV and viral haemorrhagic septicemia virus (VHSV), NAbs to both viruses were also detected in the fish from such populations, often in distinct individuals. NAb-responding fish became detectable 2-3 months post-infection (pi). The number of responding fish reached a mean prevalence of 20% between 3 and 6 months pi and disappeared after 8 months. The neutralizing serum titres (NST) were considered positive at > or = 32 and 64 for VHSV and IHNV, respectively. Both the NST results and the prevalence varied greatly according to individuals, populations and the number of repeated stimuli involved in a given serum sampling series. Conversely, the thousands of sera collected from trout in virus-free farms did not display any neutralizing activity against either VHSV or IHNV.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Husbandry↗
PubMed1978

[Local reaction and neutralization test in smallpox vaccination after previous inoculation with MVA. Stickl's graduated vaccination (author's transl)].

Of 200 first inoculations and 8 revaccinations, the sera were examined for content of neutralizing vaccine antibodies 3 weeks after the MVA graduated inoculation. In spite of imponderables which affect the failure rate in the "clinical trial", a positive result was obtained on first vaccination in 85%. In vaccinated children with a negative neutralization test a distinct booster effect was obtained with a "main vaccination" after about six months. The same effect was seen with revaccinations. For the time being inadequately controlled cerebral convulsive diseases, severe endogenous eczema, neurodermatitis, acute allergies, malignancies, immunosuppressive therapy, cortisole and intensive antirheumatic therapy and acute and purulent diseases must be considered as contraindications.

Adult↗
PubMedDate not supplied

[Use of cross-absorbed sera in neutralization tests with viral titration by the cytopathogenic effect].

A new method for intratypic antigenic differentiation of poliovirus strains has been developed. The method is based on the use of cross-absorbed sera in neutralization tests where virus is titrated by the cytopathic effect. Qualitative differences between the antigenic structure of vaccine and "wild" strains as well as between some "wild" strains of the same serologic type have been found. The method may be used in practical laboratories.

Cytopathogenic Effect, Viral↗
PubMed1980

Comparison of radioimmunoassay for internal protein of bovine leukemia virus with neutralization test employing VSV-BLV pseudotype.

Two methods for the detection of antibodies to the bovine leukemia virus (BLV) in infected animals were compared for their suitability for the early diagnosis of bovine leukemia - pseudotype neutralization test (PNT) employing vesicular stomatitis virus - bovine leukemia virus pseudotypes (VSV-BLV), and radioimmunoassay test (RIA) for major internal viral protein p24 of the BLV. The comparison was made using more than 300 sera from cows of the herds with high incidence of bovine leukemia. In infected animals the presence of antibodies against virus envelope glycoprotein detected by PNT and antibodies against major structural viral protein p24 detected by RIA were found always coincidentally. Both methods were found highly comparable and suitable for early detection of bovine leukemia virus infected animals.

Animals↗
PubMed1994

Development of an ELISA for measuring the activity of tetanus toxoid in vaccines and comparison with the toxin neutralization test in mice.

An enzyme-linked immunosorbent assay (ELISA) has been developed to measure anti-tetanus toxoid antibody levels in immunized guinea-pig sera as a useful alternative to the currently used toxin neutralization test (TNT) in determining the activity of the tetanus toxoid in vaccines. The ELISA was found to measure antibody levels as low as 5.8 x 10(-5) IU/ml. Furthermore, a comparison of the results from ELISA and TNT involving 132 different commercial vaccines showed a very good correlation (r = 0.94, p < 0.001) between antibody levels measured by both methods. The results suggest that the proposed ELISA is a reliable, simple and economical alternative to the TNT in mice for assessing the activity of tetanus toxoids in vaccines.

Animals↗
PubMed1985

The mouse neutralization test in comparison with the rapid fluorescent focus inhibition test: differences in the results in rabies antibody determinations.

Sixteen lots of rabies immune globulin (RIG) and six lots of rabies immune horse serum (RIS) from different producers were examined for rabies antibody by the standard mouse neutralization test (MNT) and the rapid fluorescent focus inhibition test (RFFIT). An equine rabies standard serum was assayed in parallel. In comparisons of RIS with this standard the MNT and RFFIT gave comparable results. In comparisons of RIG the antibody values in the MNT was two to ten times higher than that in the RFFIT in 15 out of 16 lots. The MNT and RFFIT are thus not fully comparable when measuring rabies antibodies in RIG. The choice of the titration method is obviously important in the measurement of the antibody concentration in RIG or RIS in IU against an equine rabies reference preparation. The described differences could have consequences for the use of RIG.

Animals↗
PubMed1993

A comparative evaluation of two sensitive serum neutralization tests for bovine herpesvirus-1 antibodies.

Two sensitive serum neutralization (SN) tests for the detection of antibodies to bovine herpesvirus-1 (BHV-1) in bovine sera were evaluated. Both SN tests used a 24 h incubation of test sera with 100 CCID50 of BHV-1 before the addition of susceptible cells. The tests differed in the presence (C test) or absence (D test) of complement and were compared with a standard 1 h incubation SN test and the enzyme-linked immunosorbent assay (ELISA). Although the mean titer of the C test was twofold higher than the mean titer of the D test for 310 sera, the number of samples which were negative was not significantly different between tests. For 100 sera from herds with known reactors, which were negative in a 1 h incubation SN test, 32% tested positive in the C and D tests. Other investigations, including Western immunoblotting and radioimmune precipitation, suggest that the 24 h incubation tests produce some false positive results. In contrast, the 1 h incubation SN test and, to a much lesser extent, the ELISA appear to produce some false negative results. The C test was more sensitive than the D test for detecting an early immune response after experimental infection.

Animals↗
PubMed1988

Identity of Karelian fever and Ockelbo viruses determined by serum dilution-plaque reduction neutralization tests and oligonucleotide mapping.

The causative agents of Ockelbo disease in Sweden, Pogosta disease in Finland, and Karelian fever in the USSR have been attributed to alphaviruses (family Togaviridae) related to Sindbis virus. We compared prototypes Sindbis, Ockelbo, and Karelian fever viruses by neutralization tests. We also analyzed oligonucleotide fingerprint maps of prototypes Ockelbo and Karelian fever viruses and a strain of Sindbis virus from Czechoslovakia. The results indicate that Ockelbo and Karelian fever viruses are essentially identical and suggest that Ockelbo disease, Pogosta disease, and Karelian fever are synonyms for the same disease.

Alphavirus↗
PubMed1991

Detection of bovine rhinotracheitis virus antibody by neutralizing test and ELISA in experimentally infected rabbits.

The antibody response of rabbit to infectious bovine rhinotracheitis (IBR) virus was examined. Two rabbits were inoculated with IBR virus strain Los Angeles into the trachea and intravenously, and intravenously two times, respectively. The patterns of antibody titers in the rabbits measured by neutralization test and ELISA were similar to those in the case of bovine. The antibody was detected after the inoculation, and much more antibody was detected after the second inoculation. The fact suggests that rabbits are a very useful laboratory animal for IBR virus infection studies.

Animals↗
PubMed1968

Yellow fever virus. I. Development and evaluation of a plaque neutralization test.

Heretofore, the most reliable way of measuring yellow fever virus antibody was to use the mouse neutralization (MN) test employing either suckling or weanling mice. Certain disadvantages (e.g., expense both of animals and of maintaining a mouse colony, allergic reactions of many laboratory workers, and the relatively long time, 21 days, before end points are reached) are inherent in any program with mice or other laboratory animal species and have discouraged the use of the MN test by many laboratories. A previously reported plaque neutralization (PN) test with primary chick embryo cell cultures could not be consistently reproduced by later investigators. We have developed a convenient and reproducible PN test employing the MA-104 embryonic rhesus monkey kidney cell culture and a single agar-overlay procedure. When compared with MN tests with newborn (1 to 3 days old) and weanling (16 to 20 g, 24 to 28 days old) mice inoculated by the intracranial route, the PN test was the most sensitive for measuring neutralizing antibody; it was also less variable, less costly, and it achieved results in the shortest period of time. End points could be determined in 5 to 6 days for the PN test as compared to 21 days for the MN test.

Agar↗
PubMed1985

Serotypic classification of hantaviruses by indirect immunofluorescent antibody and plaque reduction neutralization tests.

Antisera prepared against 16 strains of hantaviruses isolated from patients with hemorrhagic fever with renal syndrome (HFRS) or from rodents captured in HFRS-endemic and nonendemic regions were titrated against Hantaan virus strain 76-118, Puumala virus strain Sotkamo, and Prospect Hill virus strain Prospect Hill-I by using the indirect immunofluorescent antibody and plaque reduction neutralization tests. Isolates fell into one of four distinct groups or serotypes. Serotype 1 included Apodemus-derived strains, serotype 2 included Rattus-derived strains, serotype 3 included Clethrionomys-derived strains, and serotype 4 included Microtus-derived strains. Serotypic classification of hantavirus infections was possible for humans and rodents in widely varied geographical areas, but in a few instances, sera from patients with HFRS did not conform to any of the four serotypes, suggesting the existence of as yet unidentified serotypes. A definitive serological classification of hantaviruses must await analysis of additional virus isolates.

Animals↗
PubMed1978

Analysis of antigenic diversity among human cytomegaloviruses by kinetic neutralization tests with high-titered rabbit antisera.

Neutralizing antisera to human cytomegalovirus were produced in rabbits with alkaline-buffered extracts of infected cell cultures. The antibody activity was complement dependent and associated primarily with the 7S immunoglobulin fraction. Antisera with homologous K values greater than 10.00 were shown to be suitable for neutralization kinetic studies and were so used to examine the antigenic relatedness of strains AD169, Davis, Esp, C-87, Kerr, and Towne. Based upon the degree of relationship as determined by normalized K values, antisera to the Davis or AD169 strains discriminated three antigenic groups, and an antiserum to strain Esp discriminated two groups.

Animals↗
PubMed1993

Comparison of a monoclonal antibody capture ELISA (MACELISA) to indirect ELISA and virus neutralization test for the serodiagnosis of transmissible gastroenteritis virus.

An enzyme-linked immunosorbent assay (ELISA) in which the antigen is captured to the plate by monoclonal antibodies (MACELISA) was developed for the detection of antibodies to transmissible gastroenteritis virus (TGEV). The viral antigen was semipurified from TGEV-infected cells by simple ultracentrifugation. MACELISA results with 258 field sera were compared with those of a standard indirect ELISA and with the virus neutralization test (VNT). Sensitivity, specificity, and kappa values of MACELISA indicated a strong correlation with VNT results, whereas an indirect ELISA was less sensitive and much less specific than VNT. The serologic response of 4 pigs orally inoculated and intraperitoneally boostered with TGEV was compared using the 3 tests. Its sensitivity, specificity, and ability to use unpurified antigen make the MACELISA the advisable first step in TGEV serodiagnosis.

Animals↗
PubMed1992

A short incubation serum neutralization test for bovine viral diarrhea virus.

A three day serum neutralization (SN) test for the detection of antibodies to bovine viral diarrhea virus (BVDV), which is an improvement on the existing five day test, is described. The improved test results in a more rapid viral cytopathic effect and utilizes Madin Darby kidney (MDBK) cells, and horse serum as a medium supplement. A comparison of tests utilizing the NADL and the Singer strains of BVDV and the use of either secondary bovine kidney cells with calf serum (BKCS) or continuous MDBK cells with horse serum (MDHS) was performed. Analysis of the SN results of 685 serum samples from 445 Quebec and Ontario cattle showed that there was no difference, as expected, in the means of the SN antibody titers when the NADL strain was used in either the BKCS or MDHS system but SN antibody titers were elevated (p less than 0.01) when the Singer strain was used in the MDHS system. The SN test with the Singer strain also yielded significantly higher titers for sera from 200 Alberta cattle.

Alberta↗
PubMed1991

[The standardization of the in-vitro tetanus toxin neutralization test on Chinese hamster ovary cells].

A test for the titration of B. pertussis toxin with antisera on Chinese hamster ovary (CHO) cells has been worked out. B. pertussis protective antigenic cell-free complex containing 48-54% of B. pertussis toxin has been used as antigen. The specificity of the effect of this complex on CHO cells has been confirmed in the toxicity neutralization test with antisera. CHO cells have been adapted to reagents and culture media made in the USSR. The titration of B. pertussis toxin and antisera on CHO cells did not require the use of highly purified antigen.

Animals↗
PubMedDate not supplied

Studies on immunity to mouse sarcomas using the tumor-cell neutralization test.

Statistical analysis of the results of tumor-cell neutralization (Winn) tests has been presented in a refined manner using three variables: tumor incidence, time to palpable tumor, and growth rate. The concept of relative risk and the Z statistic were used to describe the latter two variables. This analysis is then applied to a particular experiment. Lymphocytes sensitized in vitro were compared with specifically immune lymphocytes and were found to facilitate the growth rate. Further applications of this analysis are discussed.

Absorption↗
PubMed1990

Correlation between cutaneous reaction in vaccinees immunized against smallpox and antibody titer determined by plaque neutralization test and ELISA.

The correlation between skin reaction, exhibited by vaccinees immunized against smallpox, and antibody titer determined by plaque neutralization and ELISA, was evaluated. Twenty eight out of 35 young adults (vaccinated at infancy and at the age of 8 years), who were injected with vaccinia virus, displayed a major skin reaction a week later. An increase of four-folds and more, in antibody titer against vaccinia virus, is generally considered positive immunization take-up against smallpox. According to this criterion, only 17 of the vaccinees were found positive by plaque neutralization, while 25 by the indirect micro-ELISA. Thus, there were eight vaccinees who were considered immunized by the ELISA, (seven of them also according to the skin reaction), but not by the plaque neutralization test.

Adolescent↗