scholarly journals The Role of Phosphatidylinositol Mannosides in the Serological Diagnosis of Mycobacterial Infections

2019 ◽  
Vol 6 (4) ◽  
pp. 91
Author(s):  
Ad P. Koets ◽  
Marielle H. van den Esker ◽  
Karel Riepema ◽  
Douwe Bakker
Keyword(s):  
Serological Test ◽  
Mycobacterial Infections ◽  
Diagnostic Assays ◽  
Test Sensitivity ◽  
Crude Antigen ◽  
Test Specificity ◽  
Pre Treatment ◽  
Diagnostic Applications ◽  
Indirect Tests ◽  
Phosphatidylinositol Mannosides

Accurate diagnosis of mycobacterial infections, such as bovine tuberculosis and paratuberculosis, remains challenging. Available direct diagnostic tests aimed at detecting the pathogen are highly specific but lack sensitivity, depending on the stage of infection and the prevalence of infection in a population. The sensitivity of indirect diagnostic assays that measure the host immune response to infection is similarly affected by disease characteristics. The choice of antigen used to detect a host response to infection has a critical impact on test sensitivity and specificity. Many indirect tests rely on crude antigen preparations and cell-free extracts, of which the production is poorly standardized. Moreover, these preparations contain ample uncharacterized cross-reactive compounds. To enhance serological test specificity, existing assays depend on the pre-treatment of samples and a relatively high cut-off value, that in turn influences test sensitivity. Research therefore focuses on the identification of more specific, defined antigens to improve diagnostics. In the current study, we extracted phosphatidylinositol mannosides (PIMs) and investigated their potential use in antibody-based tests. Our results demonstrate that specific IgG class antibodies are generated against PIMs in cows, but this is unrelated to tuberculosis or paratuberculosis infection status, making these antigens unsuitable for diagnostic applications. In addition, we demonstrate that PIMs are widely present in crude antigen preparations and in serum pre-absorption buffer. Our results indicate that PIMs are cross-reactive compounds with immunodominant B cell epitopes that could impair serological test specificity.

scholarly journals High variability in transmission of SARS-CoV-2 within households and implications for control

PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0259097
Author(s):  
Damon J. A. Toth ◽  
Alexander B. Beams ◽  
Lindsay T. Keegan ◽  
Yue Zhang ◽  
Tom Greene ◽  
...  
Keyword(s):  
Test Data ◽  
Attack Rate ◽  
Serological Test ◽  
Close Contact ◽  
Antibody Test ◽  
High Variability ◽  
Test Accuracy ◽  
Household Transmission ◽  
Wide Range ◽  
Test Specificity

Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a high risk of transmission in close-contact indoor settings, which may include households. Prior studies have found a wide range of household secondary attack rates and may contain biases due to simplifying assumptions about transmission variability and test accuracy. Methods We compiled serological SARS-CoV-2 antibody test data and prior SARS-CoV-2 test reporting from members of 9,224 Utah households. We paired these data with a probabilistic model of household importation and transmission. We calculated a maximum likelihood estimate of the importation probability, mean and variability of household transmission probability, and sensitivity and specificity of test data. Given our household transmission estimates, we estimated the threshold of non-household transmission required for epidemic growth in the population. Results We estimated that individuals in our study households had a 0.41% (95% CI 0.32%– 0.51%) chance of acquiring SARS-CoV-2 infection outside their household. Our household secondary attack rate estimate was 36% (27%– 48%), substantially higher than the crude estimate of 16% unadjusted for imperfect serological test specificity and other factors. We found evidence for high variability in individual transmissibility, with higher probability of no transmissions or many transmissions compared to standard models. With household transmission at our estimates, the average number of non-household transmissions per case must be kept below 0.41 (0.33–0.52) to avoid continued growth of the pandemic in Utah. Conclusions Our findings suggest that crude estimates of household secondary attack rate based on serology data without accounting for false positive tests may underestimate the true average transmissibility, even when test specificity is high. Our finding of potential high variability (overdispersion) in transmissibility of infected individuals is consistent with characterizing SARS-CoV-2 transmission being largely driven by superspreading from a minority of infected individuals. Mitigation efforts targeting large households and other locations where many people congregate indoors might curb continued spread of the virus.

Production of Monoclonal Antibodies against a New Carcinoma-associated Marker in View of Developing a Serological Test

1990 ◽  
Vol 5 (3) ◽  
pp. 109-117 ◽  
Author(s):  
E. Tagliabue ◽  
F. Centis ◽  
A. Mastroianni ◽  
S. Martignone ◽  
S. Ménard ◽  
...  
Keyword(s):  
Lung Carcinoma ◽  
Serological Test ◽  
Small Cell Lung Carcinoma ◽  
Metastatic Breast ◽  
Cell Lung Carcinoma ◽  
Normal Tissues ◽  
Diagnostic Applications ◽  
Low Sensitivity ◽  
Nsclc Patients ◽  
And Control

By immunizing a mouse with human metastatic breast tumor cells from patient effusions and infiltrated lymph nodes, a monoclonal antibody (MLuC2), which identifies a new carcinoma-associated marker, was raised. The reactivity of this reagent was studied by immunohistochemistry on live and fixed cells from tumor cell lines and on frozen sections from surgical specimens. Besides reacting with 73% of breast carcinomas, MLuC2 also reacted with 93% of non-small cell lung carcinoma (NSCLC) and with a few normal tissues. The MLuC2-recognized molecule (CaMLuC2), whose MW was 90 KDa according to immunoblotting experiments, was found to be detectable in the serum and could therefore be of particular interest for serological diagnostic applications. Since the CaMLuC2 epitope was not polyexpressed on the bearing molecule, we produced a new generation of MAbs in order to define epitopes coexpressed with CaMLuC2 on the same 90 KDa molecule, and which are therefore suitable to develop a double-determinant immunoradiometric assay (DDIRMA) for the detection of this marker in the sera of lung carcinoma patients. Different analyses by immunohistochemistry, binding inhibition tests and DDIRMA, proved that the two new reagents developed, MLuC8 and MLuC9, recognize the same or closely related epitopes, which are however different from CaMLuC2, but which are all present on the same molecule. Preliminary immunoradiometric tests performed on sera from lung cancer and control patients showed a good specificity but a low sensitivity. In fact, only 42% of the 28 tested sera samples from NSCLC patients scored positive despite the fact that more than 90% of the NSCLC expressed the relevant antigen

scholarly journals High variability in transmission of SARS-CoV-2 within households and implications for control

2021 ◽  
Author(s):  
Damon J.A. Toth ◽  
Alexander B. Beams ◽  
Lindsay T. Keegan ◽  
Yue Zhang ◽  
Tom Greene ◽  
...  
Keyword(s):  
Test Data ◽  
Attack Rate ◽  
Serological Test ◽  
Close Contact ◽  
Antibody Test ◽  
High Variability ◽  
Test Accuracy ◽  
Household Transmission ◽  
Wide Range ◽  
Test Specificity

AbstractBackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a high risk of transmission in close-contact indoor settings, which may include households. Prior studies have found a wide range of household secondary attack rates and may contain biases due to simplifying assumptions about transmission variability and test accuracy.MethodsWe compiled serological SARS-CoV-2 antibody test data and prior PCR test reporting from members of more than 9000 Utah households. We paired these data with a probabilistic model of household importation and transmission. We calculated a maximum likelihood estimate of the importation probability, mean and variability of household transmission probability, and sensitivity and specificity of test data. Given our household transmission estimates, we estimated the threshold of non-household transmission required for epidemic growth in the population.ResultsWe estimated that individuals in our study households had a 0.38% (95% CI 0.30% – 0.48%) chance of acquiring SARS-CoV-2 infection outside their household. Our household secondary attack rate estimate was 35% (26% – 47%), substantially higher than the crude estimate of 15% unadjusted for imperfect serological test specificity and other factors. We found evidence for high variability in individual transmissibility, with higher probability of no transmissions or many transmissions compared to standard models. With household transmission at our estimates, the average number of non-household transmissions per case must be kept below 0.40 (0.32 – 0.51) to avoid continued growth of the Utah epidemic.ConclusionsOur findings suggest that crude estimates of household secondary attack rate based on serology data without accounting for false positive tests may underestimate the true average transmissibility, even when test specificity is high. Our finding of potential high variability (overdispersion) in transmissibility of infected individuals is consistent with characterizing SARS-CoV-2 transmission being largely driven by superspreading from a minority of infected individuals. Mitigation efforts targeting large households and other locations where many people congregate indoors might curb continued spread of the virus.

Techniques of medical sciences

2012 ◽  
Keyword(s):  
Cost Effectiveness ◽  
Diagnostic Tests ◽  
Clinical Use ◽  
Medical Sciences ◽  
Test Sensitivity ◽  
Clinical Investigations ◽  
Clinical Scenarios ◽  
Test Specificity ◽  
Underlying Mechanisms ◽  
The Cost

There are a limited number of laboratory techniques that underlie the large number of clinical investigations that are used routinely. Knowing and understanding the basis for these tests is essential in appreciating the clinical application of the various tests. Important parameters of clinical diagnostic tests are test sensitivity—how well are those with a condition correctly identified by the test and how low is the rate of false positives; and test specificity—how well does the test correctly identify those without the condition and what is the rate of false negatives. The cost-effectiveness of a test is also an important consideration. Familiarity with the underlying mechanisms will also help students and doctors to determine when to use the tests, to realize their value and limitations, and hence to exercise caution in interpretation. This chapter has questions that test knowledge of the mechanisms underlying a variety of techniques. Their application in clinical use is tested using a number of clinical scenarios.

Nasalance and Nasality in Low Pressure and High Pressure Speech

1998 ◽  
Vol 35 (4) ◽  
pp. 293-298 ◽  
Author(s):  
Thomas Watterson ◽  
Kerry E. Lewis ◽  
Candace Deutsch
Keyword(s):  
High Pressure ◽  
Correlation Coefficient ◽  
Low Pressure ◽  
Communication Disorder ◽  
Test Sensitivity ◽  
Significant Difference ◽  
History Of ◽  
Hypernasal Speech ◽  
Test Specificity ◽  
The Mean

Objective This study compared nasalance measures and nasality ratings in low pressure (LP) and high pressure (HP) speech. Subjects The subjects for this study were 25 children ranging in age from 5 to 13 years. Twenty of the subjects were patients followed by a craniofacial team, and five had no history of communication disorder. Results The mean nasalance for the LP speech was 29.98% (SD, 16.16), and the mean nasalance for the HP speech was 30.28% (SD, 15.35). The mean nasality rating for the LP speech was 2.31, and the mean nasality rating for the HP speech was 2.59. Separate paired t tests revealed no significant difference between the LP or the HP speech for either the nasalance scores or the nasality ratings. The correlation coefficient between nasalance and nasality for the LP speech was r = 0.78, and for the HP speech r = 0.77. Using a cutoff of 26% for nasalance and 2.0 for nasality, Nasometer test sensitivity was 0.84 and test specificity was 0.88. Conclusions In general, clinicians may obtain valid measures of nasalance and/or ratings of nasality using either an LP stimulus or an HP stimulus. Sensitivity and specificity scores indicated that the Nasometer was reasonably accurate in distinguishing between normal and hypernasal speech samples.

scholarly journals Meat juice serology for Toxoplasma gondii infection in chickens

2016 ◽  
Vol 5 (1) ◽  
Author(s):  
Alice Vismarra ◽  
Carlo Mangia ◽  
Elena Barilli ◽  
Franco Brindani ◽  
Cristina Bacci ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Serological Test ◽  
Epidemiological Studies ◽  
Heart Tissue ◽  
Sample Collection ◽  
Free Range ◽  
Meat Juice ◽  
Specific Pcr ◽  
Test Specificity ◽  
Toxoplasma Gondii Infection

<em>Toxoplasma gondii</em> is an important food-borne zoonoses. Free-range chickens are at particularly high risk of infection and are also excellent indicators of soil contamination by oocysts. In the present study, hearts of 77 free-range chickens were collected at slaughter. <em>T. gondii</em> meat juice ELISA was performed with a commercial kit, following validation with positive controls, from experimentally infected chickens, and negative ones. Out of 77 samples, only 66 gave sufficient meat juice for serology. Of these, 24 (36.4%) were positive for <em>T. gondii</em> considering the 5*SD values (calculated on the OD of negative controls) while all the samples were negative considering S/P% values. Parasite-specific PCR was carried out on all samples obtained from heart tissue and none were positive for the presence of T. gondii DNA. Results would suggest that further study on the use of meat juice with a validated serological test to detect <em>T. gondii</em> in chickens could lead to widespread epidemiological studies in this important intermediate host. However, sample collection and test specificity require further evaluation.

scholarly journals Bayes Lines Tool (BLT): a SQL-script for analyzing diagnostic test results with an application to SARS-CoV-2-testing

F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 369
Author(s):  
Wouter Aukema ◽  
Bobby Rajesh Malhotra ◽  
Simon Goddek ◽  
Ulrike Kämmerer ◽  
Peter Borger ◽  
...  
Keyword(s):  
Sensitivity And Specificity ◽  
Query Language ◽  
False Negative ◽  
Disease Prevalence ◽  
Test Results ◽  
True Negative ◽  
Test Sensitivity ◽  
Laboratory Test Results ◽  
Test Specificity ◽  
Analytical Reagents

The performance of diagnostic tests crucially depends on the disease prevalence, test sensitivity, and test specificity. However, these quantities are often not well known when tests are performed outside defined routine lab procedures which make the rating of the test results somewhat problematic. A current example is the mass testing taking place within the context of the world-wide SARS-CoV-2 crisis. Here, for the first time in history, laboratory test results have a dramatic impact on political decisions. Therefore, transparent, comprehensible, and reliable data is mandatory. It is in the nature of wet lab tests that their quality and outcome are influenced by multiple factors reducing their performance by handling procedures, underlying test protocols, and analytical reagents. These limitations in sensitivity and specificity have to be taken into account when calculating the real test results. As a resolution method, we have developed a Bayesian calculator, the Bayes Lines Tool (BLT), for analyzing disease prevalence, test sensitivity, test specificity, and, therefore, true positive, false positive, true negative, and false negative numbers from official test outcome reports. The calculator performs a simple SQL (Structured Query Language) query and can easily be implemented on any system supporting SQL. We provide an example of influenza test results from California, USA, as well as two examples of SARS-CoV-2 test results from official government reports from The Netherlands and Germany-Bavaria, to illustrate the possible parameter space of prevalence, sensitivity, and specificity consistent with the observed data. Finally, we discuss this tool’s multiple applications, including its putative importance for informing policy decisions.

scholarly journals Evaluation of eight commercial Zika virus IgM and IgG serology assays for diagnostics and research

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0244601
Author(s):  
Swee Ling Low ◽  
Yee Sin Leo ◽  
Yee Ling Lai ◽  
Sally Lam ◽  
Hwee Huang Tan ◽  
...  
Keyword(s):  
Zika Virus ◽  
Blood Donors ◽  
Cross Reactivity ◽  
Public Health Emergency ◽  
Test Interpretation ◽  
Test Sensitivity ◽  
Endemic Setting ◽  
Igm Elisa ◽  
Test Specificity ◽  
High Test

Several commercial Zika virus (ZIKV) serology assays have been developed since the recognition of ZIKV outbreaks as a Public Health Emergency of International Concern in 2016. However, test interpretation for ZIKV serology can be challenging due to antibody cross-reactivity with other flaviviruses like dengue virus (DENV). Therefore, we sought to evaluate the performance of eight commercially available ZIKV IgM and IgG assays across three testing platforms, namely, immunochromatographic tests (ICT), ELISAs and immunofluorescence tests (IIFT). The test panel comprised of 278 samples, including acute and convalescent sera or plasma from ZIKV-confirmed, DENV-confirmed, non-ZIKV and non-DENV patients, and residual sera from healthy blood donors. The ZIKV IgM and IgG serology assays yielded higher test sensitivities of 23.5% - 97.1% among ZIKV convalescent samples as compared to 5.6% - 27.8% among ZIKV acute samples; the test specificities were 63.3% - 100% among acute and convalescent DENV, non-DENV samples. Among the ELISAs and IIFTs, the Diapro ZIKV IgM ELISA demonstrated high test sensitivity (96%) and specificity (80%) when tested on early convalescent samples, while the Euroimmun ZIKV IgG ELISA yielded the highest test specificity of 97% - 100% on samples from non-ZIKV patients and healthy blood donors. For rapid ICTs, the LumiQuick IgM rapid ICT yielded low test sensitivity, suggesting its limited utility. We showed that commercial ZIKV IgM and IgG serology assays have differing test performances, with some having moderate to high test sensitivities and specificities when used in a dengue endemic setting, although there were limitations in IgG serology.

scholarly journals Evaluation of Bias in Diagnostic-Test Sensitivity and Specificity Estimates Computed by Discrepant Analysis

1998 ◽  
Vol 36 (2) ◽  
pp. 375-381 ◽  
Author(s):  
Timothy A. Green ◽  
Carolyn M. Black ◽  
Robert E. Johnson
Keyword(s):  
Cell Culture ◽  
Nucleic Acid ◽  
Diagnostic Test ◽  
Sensitivity And Specificity ◽  
Nucleic Acid Amplification ◽  
Reference Test ◽  
Test Sensitivity ◽  
Test Specificity ◽  
Positive Results

When a new diagnostic test is potentially more sensitive than the reference test used to classify persons as infected or uninfected, a substantial number of specimens from infected persons may be reference-test negative but new-test positive. Discrepant analysis involves the performance of one or more additional tests with these specimens, reclassification as infected those persons for whom the new-test-positive results are confirmed, and recalculation of the estimates of new-test sensitivity and specificity by using the revised classification. This approach has been criticized because of the bias introduced by the selective use of confirmation testing. Under conditions appropriate for evaluating a nucleic acid amplification (NAA) test for Chlamydia trachomatis infection with cell culture as the reference test, we compared the bias in estimates based on the discrepant-analysis classification of persons as infected or uninfected with that in estimates based on the culture classification. We concluded that the bias in estimates of NAA-test specificity based on discrepant analysis is small and generally less than that in estimates based on culture. However, the accuracy of discrepant-analysis-based estimates of NAA-test sensitivity depends critically on whether culture specificity is equal to or is slightly less than 100%, and it is affected by competing biases that are not fully taken into account by discrepant analysis.

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