DIAGNOSTIC TESTS FOR TOXOPLASMOSIS

PEDIATRICS ◽  
1949 ◽  
Vol 4 (4) ◽  
pp. 490-497
Author(s):  
F. H. ADAMS ◽  
P. KABLER ◽  
M. COONEY ◽  
J. M. ADAMS
Keyword(s):  
Diagnostic Tests ◽  
Complement Fixation ◽  
Neutralization Test ◽  
Correlation Study ◽  
Positive Test ◽  
Prozone Phenomenon

Results of a correlation study of the rabbit neutralization, complement fixation, skin and slide neutralization tests for toxoplasmosis are presented. The agreement between these is fairly striking, except those from the complement test. Reversal of a positive test was found to occur in the sera of six patients, and, in three instances, the prozone phenomenon was revealed. The new slide neutralization test of Sabin and Feldman appears to be the most accurate, the most economical and the quickest test available at present for the diagnosis of toxoplasmosis.

scholarly journals A localized outbreak of dengue fever in Kuala Lumpur: serological aspects

1957 ◽  
Vol 55 (2) ◽  
pp. 207-223 ◽  
Author(s):  
C. E. Gordon Smith
Keyword(s):  
Dengue Fever ◽  
Neutralizing Antibodies ◽  
Complement Fixation Test ◽  
Complement Fixation ◽  
Neutralization Test ◽  
High Titre ◽  
Inhibition Test ◽  
Kuala Lumpur ◽  
Clear Identification ◽  
Serial Serum

1. Sera from an outbreak of about forty cases of dengue fever due to dengue-1 virus have been studied using the neutralization, haemagglutinin-inhibition, and complement-fixation tests.2. The neutralization test was the most specific and the complement-fixation test the least so.3. The neutralization test is essential for clear identification of the causal virus by serological means, and serial serum specimens from each patient must be examined.4. The haemagglutinin-inhibition test can be used to screen patients in outbreaks where some cases have been fully identified by neutralization tests.5. Homologous neutralizing antibodies persist in high titre for at least 30 weeks after infection, while heterologous antibodies have disappeared by that time.6. Both haemagglutinin-inhibiting and complement-fixing antibodies to homologous and heterologous viruses usually persist for at least 30 weeks, although the homologous titres tend to be highest.7. The implications of these findings in serological surveys are discussed.8. Some evidence suggesting the occurrence of inapparent infections during the epidemic is presented.I am greatly indebted to my staff for help with this work: especially to my senior technician, Che Ali bin Mohamed Amin, and to Che Mohamed bin Omar who drew the figures.

scholarly journals Sensitivity of anti-SARS-CoV-2 serological assays in a high-prevalence setting

2021 ◽  
Author(s):  
Lisa Müller ◽  
Philipp Niklas Ostermann ◽  
Andreas Walker ◽  
Tobias Wienemann ◽  
Alexander Mertens ◽  
...  
Keyword(s):  
Neutralization Test ◽  
Positive Test ◽  
Test Results ◽  
Immunofluorescence Test ◽  
Neutralization Titer ◽  
Serological Tests ◽  
High Prevalence

AbstractEvaluation and power of seroprevalence studies depend on the performed serological assays. The aim of this study was to assess four commercial serological tests from EUROIMMUN, DiaSorin, Abbott, and Roche as well as an in-house immunofluorescence and neutralization test for their capability to identify SARS-CoV-2 seropositive individuals in a high-prevalence setting. Therefore, 42 social and working contacts of a German super-spreader were tested. Consistent with a high-prevalence setting, 26 of 42 were SARS-CoV-2 seropositive by neutralization test (NT), and immunofluorescence test (IFT) confirmed 23 of these 26 positive test results (NT 61.9% and IFT 54.8% seroprevalence). Four commercial assays detected anti-SARS-CoV-2 antibodies in 33.3-40.5% individuals. Besides an overall discrepancy between the NT and the commercial assays regarding their sensitivity, this study revealed that commercial SARS-CoV-2 spike-based assays are better to predict the neutralization titer than nucleoprotein-based assays are.

scholarly journals Plaque assay of Sendai virus in monolayers of a clonal line of porcine kidney cells

1976 ◽  
Vol 3 (2) ◽  
pp. 91-95
Author(s):  
H Ito
Keyword(s):  
Complement Fixation ◽  
Sendai Virus ◽  
Neutralization Test ◽  
Plaque Assay ◽  
Kidney Cells ◽  
Porcine Kidney ◽  
Clonal Line ◽  
In Ovo ◽  
Serum Neutralization Test ◽  
Porcine Kidney Cell

The MN strain of Sendai virus formed distinct plaques in monolayers of PS-Y15 cells, an established porcine kidney cell line. The plaque-forming ability was neutralized by specific antibody to the virus. A linear relationship was found between the concentration of virus and the number of plaques. The sensitivity of this assay was about equal to that of the in ovo titration. When applied to the serum neutralization test, the end points obtained were comparable to those of the hemagglutination-inhibition and complement-fixation tests.

scholarly journals Repeat COVID-19 Molecular Testing: Correlation of SARS-CoV-2 Culture with Molecular Assays and Cycle Thresholds

2020 ◽  
Author(s):  
Victoria Gniazdowski ◽  
C Paul Morris ◽  
Shirlee Wohl ◽  
Thomas Mehoke ◽  
Srividya Ramakrishnan ◽  
...  
Keyword(s):  
Cell Culture ◽  
Genome Sequencing ◽  
Diagnostic Tests ◽  
Viral Rna ◽  
Positive Test ◽  
Molecular Testing ◽  
Whole Genome ◽  
Test Results ◽  
Virus Growth ◽  
Over Time

Abstract Background Repeat COVID-19 molecular testing can lead to positive test results after negative tests and to multiple positive test results over time. The association between positive tests and infectious virus is important to quantify. Methods A two months cohort of retrospective data and consecutively collected specimens from COVID-19 patients or patients under investigation were used to understand the correlation between prolonged viral RNA positive test results, cycle threshold (Ct) values and growth of SARS-CoV-2 in cell culture. Whole genome sequencing was used to confirm virus genotype in patients with prolonged viral RNA detection. Droplet digital PCR (ddPCR) was used to assess the rate of false negative COVID-19 diagnostic tests. Results In two months, 29,686 specimens were tested and 2,194 patients received repeated testing. Virus recovery in cell culture was noted in specimens with SARS-CoV-2 target genes’ Ct value average of 18.8 ± 3.4. Prolonged viral RNA shedding was associated with positive virus growth in culture in specimens collected up to 20 days after the first positive result but mostly in individuals symptomatic at time of sample collection. Whole genome sequencing provided evidence the same virus was carried over time. Positive tests following negative tests had Ct values higher than 29.5 and were not associated with virus culture. ddPCR was positive in 5.6% of negative specimens collected from COVID-19 confirmed or clinically suspected patients. Conclusions Low Ct values in SARS-CoV-2 diagnostic tests were associated with virus growth in cell culture. Symptomatic patients with prolonged viral RNA shedding can also be infectious.

scholarly journals The titration of influenza virus-neutralizing antibodies

1952 ◽  
Vol 50 (2) ◽  
pp. 265-274 ◽  
Author(s):  
Forrest Fulton ◽  
J. E. Friend
Keyword(s):  
Influenza Virus ◽  
Neutralizing Antibodies ◽  
Complement Fixation Test ◽  
Complement Fixation ◽  
Neutralization Test ◽  
Inhibitory Effect ◽  
Serum Dilution ◽  
Short Time ◽  
Virus Strains ◽  
Selection Of

A method of titrating influenza virus-neutralizing antibodies is described. This method is based on the technique for cultivating virus in fragments of chick chorio-allantoic membrane using a special plastic tray with cups for 100 replicates. The neutralization test cannot be made directly by adding the antiserum to the cups in which the virus is growing in the membrane fragments because there is a significant non-specific inhibitory effect. Therefore, use is made of the observation that virus added to the cups is rapidly fixed by the membrane so that, after a short time, the membrane may be washed and transferred to a fresh cup which will later be found to contain the new virus released from the membrane.In the neutralization test the membrane fragments are exposed to virus-serum mixtures for 18 hr. and then transferred to other cups without serum to determine which pieces have become infected. The titre of neutralizing antibodies is defined as the serum dilution which will protect from infection with 100 ID 50 of virus, half of a large number of replicate pieces of membrane.The neutralization technique has been applied to the antigenic comparison of six strains of influenza virus. The results support the relationships disclosed between the six strains by a complement-fixation technique. It is suggested, however, that the neutralization technique, because of its greater specificity, and because of its dependence on the infectivity of the strain, is not as satisfactory as the complement-fixation test for strain comparisons. Apart from its use for titrating neutralizing antibodies, the technique may also be of value for proving the virtual identity of two virus strains and in the selection of strains for a vaccine.It is a pleasure to acknowledge the help given by Dr Isaacs of the WHO Influenza Centre. Not only did he provide many of the virus strains and antisera, but he also undertook the purification of the WS strain.

scholarly journals Comparison of three tests for the serological diagnosis of lymphocytic choriomeningitis virus infection

1975 ◽  
Vol 2 (3) ◽  
pp. 193-197
Author(s):  
V J Lewis ◽  
P D Walter ◽  
W L Thacker ◽  
W G Winkler
Keyword(s):  
Complement Fixation ◽  
Neutralization Test ◽  
Fluorescent Antibody ◽  
Lymphocytic Choriomeningitis ◽  
Lymphocytic Choriomeningitis Virus ◽  
The Other ◽  
Virus Antibody ◽  
Infected Cells ◽  
Lymphocytic Choriomeningitis Virus Infection ◽  
High Level

Levels of lymphocytic choriomeningitis virus antibody were assayed in 62 infected persons. The three tests used were indirect fluorescent antibody (IFA), complement fixation, and neutralization in mice. The sera first became positive by the IFA test, and IFA titers rapidly rose to a relatively high level, with the sera remaining positive long after the antibody detectable by complement fixation had disappeared. The IFA test appeared to be specific. The sera became positive last by the mouse neutralization test; with this test, antibody first appeared several weeks after infection. Virus-infected cells were stable when stored at -60 C, allowing diagnostic sera to be tested promptly by the IFA test. The IFA test for lymphocytic choriomeningitis antibody should increase the number of serological diagnoses, since it is not only rapid and specific, but detects cases not diagnosed by the other methods.

scholarly journals Microneutralization tests for serological typing and subtyping of foot-and-mouth disease virus strains

1978 ◽  
Vol 81 (1) ◽  
pp. 107-123 ◽  
Author(s):  
M. M. Rweyemamu ◽  
J. C. Booth ◽  
Morwen Head ◽  
T. W. F. Pay
Keyword(s):  
Complement Fixation Test ◽  
Complement Fixation ◽  
Neutralization Test ◽  
Foot And Mouth Disease ◽  
Fixation Test ◽  
Viral Contamination ◽  
Serological Typing ◽  
Mouth Disease Virus ◽  
Virus Strains ◽  
Microneutralization Test

SUMMARYA microneutralization test for serotyping of FMD viruses is described. It is based on earlier observations by Booth, Rweyemamu & Pay (1978) that dose-response relationships in quantal microneutralizations often deviated from linearity. The typing test described therefore utilizes undiluted virus preparations. In about 90% of samples a positive typing was obtained in contrast with about 50% for the complement fixation test. The test was also found to be susceptible to minimal quantities of heterotypic viral contamination.For strain differentiation the microneutralization test was carried out as a checkerboard test. When compared with the complement fixation test it was found to be more specific. The necessity to utilize virus-neutralization test systems for comparing (FMD) virus strains particularly for the purpose of vaccine selection is emphasized. The two dimensional microneutralization test has been applied to a study of comparing FMDV vaccine strains for Europe, South America, the Middle East and East Africa.

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