Serum Adsorption Study to Validate the Specificity of a Rapid Test to Detect Strongyloides stercoralis Infection

2021 ◽  
Author(s):  
Rahmah Noordin ◽  
Emelia Osman ◽  
Nor Suhada Anuar ◽  
Nor Mustaiqazah Juri ◽  
Anizah Rahumatullah ◽  
...  
Keyword(s):  
Small Sample Size ◽  
Rapid Test ◽  
High Specificity ◽  
Strongyloides Stercoralis ◽  
Cross Reactivity ◽  
Small Sample ◽  
Polystyrene Microspheres ◽  
Diagnostic Specificity ◽  
Serum Samples ◽  
Rapid Tests

A lateral flow rapid test for strongyloidiasis will greatly facilitate the control and elimination of the disease. Previously SsRapid™ prototype rapid test showed high diagnostic specificity to detect Strongyloides infection, determined using non-Strongyloides sera negative by IgG-ELISAs. Since high specificity is crucial before a test is used for public health control activities, further validation of its specificity is needed. Also, it needs to be ascertained whether non-Strongyloides sera positive by IgG-ELISAs and SsRapid are truly positive for Strongyloides or are cases of cross-reactivity. We performed 84 rapid tests (two types of dipsticks and cassettes) using 34 serum samples. They were divided into four groups based on Strongyloides infection and coinfection with other parasites and the availability of recombinant proteins and rapid tests for the latter. Sera was adsorbed using polystyrene microspheres beads separately coated with four recombinant parasite proteins. The small sample size is a limitation of this study; however, the overall results showed that the sera adsorption procedure was successful, and the SsRapid test is specific.

scholarly journals Development of Vasoinhibin-Specific Monoclonal Antibodies

2021 ◽  
Vol 12 ◽  
Author(s):  
Nils Müller ◽  
Juan Pablo Robles ◽  
Magdalena Zamora ◽  
Johannes Ebnet ◽  
Hülya Markl-Hahn ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Serum Proteins ◽  
Limit Of Detection ◽  
Sandwich Elisa ◽  
Vascular Diseases ◽  
High Specificity ◽  
Cross Reactivity ◽  
Dimensional Structure ◽  
Serum Samples ◽  
Limit Of Quantitation

Vasoinhibin is a protein hormone with antiangiogenic, antivasodilatatory, and antivasopermeability effects generated by the proteolytic cleavage of prolactin. The discovery of its role in diabetic retinopathy and peripartum cardiomyopathy led to the evaluation of new pharmacological treatments in clinical interventional trials. However, the quantitative evaluation of vasoinhibin in biological samples from patients has not been possible due to the lack of vasoinhibin-specific antibodies. Recently, loop 1 of vasoinhibin was identified to have a different three-dimensional structure compared to PRL, and thus to contain vasoinhibin-specific epitopes. Here, we report the development of two sets of vasoinhibin-specific monoclonal antibodies against two neighboring regions of the vasoinhibin loop 1. An experimental sandwich ELISA with two monoclonal anti-vasoinhibin antibodies was developed, which had no cross-reactivity to recombinant human full-length prolactin. The ELISA had a quantitation limit of 100 ng/ml, and intra-assay- and inter-assay coefficients of variation of 12.5% and 14%, respectively. The evaluation of 15 human serum samples demonstrated concentrations of below limit of detection (n=3), below limit of quantitation (n=1) and between 0.23 µg/ml (230 ng/ml) to 605 µg/ml (n=12) in the quantifiable range. Despite the high specificity of the monoclonal-monoclonal antibody sandwiches which discriminate vasoinhibin from PRL, there might be cross-reactivities by serum proteins other than vasoinhibin. A fully established vasoinhibin ELISA may support diagnostic and therapeutic measures in vascular diseases.

scholarly journals Development of a Dual Monoclonal Antibody Immunoassay for Total Human Kallikrein 2

2001 ◽  
Vol 47 (7) ◽  
pp. 1218-1224 ◽  
Author(s):  
Judith A Finlay ◽  
John R Day ◽  
Cindy L Evans ◽  
Robert Carlson ◽  
Kristine Kuus-Reichel ◽  
...  
Keyword(s):  
Specific Antigen ◽  
High Specificity ◽  
Cross Reactivity ◽  
Minimum Detectable Concentration ◽  
Serum Samples ◽  
Bodily Fluids ◽  
Before And After ◽  
Detectable Concentration ◽  
Human Kallikrein 2 ◽  
Kallikrein 2

Abstract Background: Human kallikrein 2 (hK2) shares 80% sequence identity with prostate-specific antigen (PSA). Because both hK2 and hK2-α1-antichymotrypsin (hK2-ACT) complexes have been identified in patient sera, we devised an immunoassay for total hK2 [(thK2); hK2 and hK2-ACT] and evaluated it in healthy subjects and patients with prostate disease. Methods: We developed monoclonal antibodies (mAbs) with high specificity for hK2 and hK2-ACT and minimal cross-reactivity to PSA. Using these mAbs, a sandwich assay was developed and its specificity for forms of hK2 was assessed. Serum samples (n = 1035) from healthy volunteers, patients with increased PSA, and men who had undergone radical prostatectomy were assayed for thK2. We also measured thK2 in samples before and after storage under common laboratory conditions. Results: The minimum detectable concentration in the thK2 assay was 0.008 μg/L, and PSA cross-reactivity was <0.001%. The assay detected prohK2 and three different hK2–serum protease complexes. The median serum concentration of thK2 in control samples (0.013 μg/L) was significantly lower than the median in samples from patients with increased PSA concentrations (0.085 μg/L). Immunoreactive hK2 changed little in samples stored for up to 1 month at −70 °C. Conclusions: The thK2 assay recognizes all forms of hK2 that have been found in bodily fluids to date.

Sensitivity of the STAT-VIEW rapid self-test and implications for use during acute HIV infection

2017 ◽  
Vol 94 (7) ◽  
pp. 475-478 ◽  
Author(s):  
Narjis Boukli ◽  
Anders Boyd ◽  
Noémie Wendremaire ◽  
Pierre-Marie Girard ◽  
Julie Bottero ◽  
...  
Keyword(s):  
Hiv Infection ◽  
Point Of Care ◽  
Rapid Test ◽  
Detection Sensitivity ◽  
Serum Samples ◽  
Acute Hiv Infection ◽  
Hiv Rna ◽  
Rapid Tests ◽  
Acute Hiv ◽  
Self Test

ObjectivesHIV testing is an important step towards diminishing incident infections. Rapid self-tests whose use is becoming more common in France could help increase access to testing, yet could fail to diagnose HIV during acute HIV infection (AHI). The aim of the present study was to evaluate HIV-detection sensitivity of a commonly used rapid self-test (STAT-VIEW HIV1/2), compared with another point-of-care rapid test (INSTI), among patients presenting with AHI.MethodsIndividuals tested at Saint-Antoine Hospital (Paris, France) with negative or indeterminate western blot (WB) results and detectable HIV-RNA were included. Rapid tests were performed retrospectively on stored serum. Patients with and without reactive rapid tests were compared, while probability of having a reactive test was modelled across infection duration using logistic regression.ResultsOf the 40 patients with AHI, 23 (57.5%) had a reactive STAT-VIEW rapid test. Patients with non-reactive versus reactive tests had a significantly shorter median time since infection (p=0.01), time since onset of symptoms (p=0.009), higher proportion with Fiebig stage III versus IV (p=0.003), negative WB results (p=0.007), higher HIV-RNA levels (p=0.001) and lower CD4+ and CD8+ cell count (p=0.03, p<0.001, respectively). When examining sensitivity over the course of AHI duration, the probability of HIV detection was 75.5% at 5 weeks from HIV transmission. The INSTI provided similar results with respect to proportion of reactive tests (62.5%), determinants for non-reactive test and probability of HIV detection at 5 weeks of infection (85.0%).ConclusionsOver half of AHI patients had reactive serology using the STAT-VIEW rapid self-test when performed on serum samples. Considering that detection sensitivity increased substantially over infection time, individuals should not rely on a negative result to accurately exclude HIV infection within at least 5 weeks of potential HIV exposure. Notwithstanding strong recommendations against rapid test use during AHI, some utility in detecting HIV is observed 5–12 weeks after transmission.

A filtration-based rapid test using a partially purified third-stage larval antigen to detect specific antibodies for the diagnosis of gnathostomiasis

2017 ◽  
Vol 93 (1) ◽  
pp. 26-32 ◽  
Author(s):  
A. Ma ◽  
Y. Wang ◽  
X.L. Liu ◽  
H.M. Zhang ◽  
P. Eamsobhana ◽  
...  
Keyword(s):  
Rapid Test ◽  
Cross Reactivity ◽  
Serum Samples ◽  
Serological Tests ◽  
Promising Tool ◽  
Diagnostic Potential ◽  
Food Borne ◽  
Third Stage ◽  
Diagnostic Sensitivity And Specificity ◽  
Purified Antigen

AbstractHuman gnathostomiasis is an emerging food-borne parasitic disease caused by nematodes of the genusGnathostoma. Currently, serological tests are commonly applied to support clinical diagnosis. In the present study, a simple and rapid filtration-based test, dot immune–gold filtration assay (DIGFA) was developed using a partially purified antigen ofGnathostomathird-stage larvae (L3). A total of 180 serum samples were tested to evaluate the diagnostic potential of DIGFA for gnathostomiasis. The diagnostic sensitivity and specificity were 96.7% (29/30) and 100% (25/25), respectively. The cross-reactivity with sera from other helminthiasis patients ranged from 0 to 4%, with an average of 1.6% (2/125). DIGFA using a partially purified L3 antigen was not only simple and rapid, but also more accurate than standard assays for the diagnosis of human gnathostomiasis. DIGFA may represent a promising tool for application in laboratories or in the field, without requiring any instrumentation.

scholarly journals Comparative Accuracy of the InBios Scrub Typhus Detect IgM Rapid Test for the Detection of IgM Antibodies by Using Conventional Serology

2015 ◽  
Vol 22 (10) ◽  
pp. 1130-1132 ◽  
Author(s):  
Hugh W. F. Kingston ◽  
Stuart D. Blacksell ◽  
Ampai Tanganuchitcharnchai ◽  
Achara Laongnualpanich ◽  
Buddha Basnyat ◽  
...  
Keyword(s):  
Rapid Diagnostic Test ◽  
Scrub Typhus ◽  
Specific Antigen ◽  
Rapid Test ◽  
Febrile Illness ◽  
High Specificity ◽  
Immunofluorescence Assay ◽  
Serum Samples ◽  
Igm Antibodies ◽  
Comparative Accuracy

ABSTRACTThis study investigated the comparative accuracy of a recombinant 56-kDa type-specific antigen-based rapid diagnostic test (RDT) for scrub typhus for the detection of IgM antibodies by using conventional serology in well-characterized serum samples from undifferentiated febrile illness patients. The RDT showed high specificity and promising comparative accuracy, with 82% sensitivity and 98% specificity for samples defined positive at an IgM indirect immunofluorescence assay positivity cutoff titer of ≥1:1,600 versus 92% and 95% at ≥1:6,400, respectively.

scholarly journals MixTwice: large-scale hypothesis testing for peptide arrays by variance mixing

2021 ◽  
Author(s):  
Zihao Zheng ◽  
Aisha M Mergaert ◽  
Irene M Ong ◽  
Miriam A Shelef ◽  
Michael A Newton
Keyword(s):  
Large Scale ◽  
Small Sample Size ◽  
Model Fitting ◽  
Small Sample ◽  
Optimization Techniques ◽  
Supplementary Information ◽  
Peptide Arrays ◽  
Serum Samples ◽  
Mixing Distributions ◽  
Variance Parameters

Abstract Summary Peptide microarrays have emerged as a powerful technology in immunoproteomics as they provide a tool to measure the abundance of different antibodies in patient serum samples. The high dimensionality and small sample size of many experiments challenge conventional statistical approaches, including those aiming to control the false discovery rate (FDR). Motivated by limitations in reproducibility and power of current methods, we advance an empirical Bayesian tool that computes local FDR statistics and local false sign rate statistics when provided with data on estimated effects and estimated standard errors from all the measured peptides. As the name suggests, the MixTwice tool involves the estimation of two mixing distributions, one on underlying effects and one on underlying variance parameters. Constrained optimization techniques provide for model fitting of mixing distributions under weak shape constraints (unimodality of the effect distribution). Numerical experiments show that MixTwice can accurately estimate generative parameters and powerfully identify non-null peptides. In a peptide array study of rheumatoid arthritis, MixTwice recovers meaningful peptide markers in one case where the signal is weak, and has strong reproducibility properties in one case where the signal is strong. Availabilityand implementation MixTwice is available as an R software package https://cran.r-project.org/web/packages/MixTwice/. Supplementary information Supplementary data are available at Bioinformatics online.

scholarly journals Using prenatal blood samples to validate COVID-19 rapid serologic tests

2020 ◽  
Author(s):  
Jackeline Alger ◽  
Maria Luisa Cafferata ◽  
Tito Alvarado ◽  
Alvaro Ciganda ◽  
Arturo Corrales ◽  
...  
Keyword(s):  
Diagnostic Tests ◽  
Population Based ◽  
Cross Reactivity ◽  
Rapid Diagnostic Tests ◽  
Serum Samples ◽  
Serologic Tests ◽  
Rapid Tests ◽  
Unique Source ◽  
Blood Specimens ◽  
One Year

Abstract IntroductionBackground cross-reactivity with other coronaviruses may reduce the specificity of COVID-19 rapid serologic tests. Blood collected during prenatal care is a unique source of population-based samples appropriate for validation studies. We used stored 2018 serum samples from an existing pregnancy cohort study to evaluate the specificity of COVID-19 serologic rapid diagnostic tests. MethodsWe randomly selected 120 stored serum samples from pregnant women enrolled in a cohort in 2018, at least one year before the COVID-19 pandemic. We used stored serum to evaluate four lateral flow rapid diagnostic tests, following manufacturers’ instructions. Pictures were taken for all tests and read by two blinded trained evaluators. Results We evaluated 120, 80, 90, and 90 samples, respectively. Specificity for both IgM and IgG was 100% for the first two tests. The third test had a specificity of 98.9% for IgM and 94.4% for IgG. The fourth test had a specificity of 88.9% for IgM and 100% for IgG.Discussion COVID-19 serologic rapid tests are of variable specificity. Blood specimens from sentinel prenatal clinics provide an opportunity to validate serologic tests with population-based samples.

scholarly journals A Serum Analysis before and after Antidepressant Treatment in Major Depression: A Pilot Study

2015 ◽  
Vol 6 ◽  
pp. CMPsy.S20765
Author(s):  
Murielle Girard ◽  
Karine Vuilliers-Devillers ◽  
Emilie Pinault ◽  
Barbara Bessette ◽  
Brigitte Plansont ◽  
...  
Keyword(s):  
Pilot Study ◽  
Clinical Improvement ◽  
Rating Scale ◽  
Serum Proteins ◽  
Antidepressant Treatment ◽  
Small Sample Size ◽  
Two Dimensions ◽  
Small Sample ◽  
Complement C3 ◽  
Serum Samples

We investigated the serum protein profiles of subjects with major depressive disorder (MDD), with (n = 4) and without clinical improvement (n = 4), at the initiation of antidepressant treatment (venlafaxine) (T0) and 4 weeks later (T28), by difference gel electrophoresis in two dimensions (2D-DIGE) and mass spectrometry. The nine proteins displaying differences in composition between the two time points in the group with clinical improvement between T0 and T28 included gelsolin, clusterin, and the activated fragment of complement C3 (C3a). We then analyzed serum samples from MDD subjects receiving different antidepressants between T0 and T28. Subjects were classified into two groups, with (n = 17) or without (n = 14) clinical improvement (>50% decrease in baseline Hamilton Depression Rating Scale score), at T28. Clusterin levels did not differ between groups at either time point. Gelsolin and C3a levels differed between T0 and T28 only in the group presenting clinical improvement. A comparison with serum samples from controls suggested that the levels of these two proteins changed during MDD and were potentially modified after successful antidepressant treatment. Despite the small sample size, the results of this pilot study suggest that several changes in the expression of some serum proteins occur in association with the clinical relevance of the treatment, and indicate changes to general pathways requiring further study.

Evidence for Toxoplasma gondii in migratory vs. nonmigratory herbivores in a terrestrial arctic ecosystem

2015 ◽  
Vol 93 (8) ◽  
pp. 671-675 ◽  
Author(s):  
S.A. Elmore ◽  
G. Samelius ◽  
C. Fernando ◽  
R.T. Alisauskas ◽  
E.J. Jenkins
Keyword(s):  
Toxoplasma Gondii ◽  
Small Sample Size ◽  
Small Sample ◽  
Arctic Ecosystems ◽  
Serum Samples ◽  
Arctic Ecosystem ◽  
Chen Caerulescens ◽  
Snow Geese ◽  
Lesser Snow Geese ◽  
Ross's Geese

It is currently unclear how Toxoplasma gondii (Nicolle and Manceaux, 1908) persists in arctic tundra ecosystems in the absence of felid definitive hosts. To investigate potential transmission routes of T. gondii in a terrestrial arctic food web, we collected samples from two migratory herbivores, Ross’s Geese (Chen rossi (Cassin, 1861)) and Lesser Snow Geese (Chen caerulescens (L., 1758)), and from two resident herbivores, Nearctic brown lemmings (Lemmus trimucronatus (Richardson, 1825)) and collared lemmings (Dicrostonyx groenlandicus (Traill, 1823)), trapped at Karrak Lake, Nunavut, Canada. Antibodies were detected in 76 of 234 (32.4%) serum samples from Ross’s Geese and 66 of 233 (28.3%) serum samples from Lesser Snow Geese. We did not detect T. gondii antibodies in filter-paper eluate tested from thoracic fluid samples collected from 84 lemmings. We did not detect T. gondii DNA in brain tissue from these lemmings. Although a small sample size, our findings suggest that lemmings in this terrestrial arctic ecosystem are not exposed to, or infected with, the parasite. This suggests that oocysts are not introduced into the terrestrial arctic ecosystem at Karrak Lake via freshwater runoff from temperate regions. This study demonstrated that live adult arctic-nesting geese are exposed to T. gondii and therefore migratory herbivorous hosts are potential sources of T. gondii infection for predators in terrestrial arctic ecosystems.

scholarly journals Performance Characteristics of Four High-Throughput Immunoassays for Detection of IgG Antibodies against SARS-CoV-2

2020 ◽  
Vol 58 (8) ◽  
Author(s):  
Elitza S. Theel ◽  
Julie Harring ◽  
Heather Hilgart ◽  
Dane Granger
Keyword(s):  
High Throughput ◽  
High Sensitivity ◽  
High Specificity ◽  
Cross Reactivity ◽  
Clinical Diagnostics ◽  
Igg Antibodies ◽  
Serum Samples ◽  
Predictive Values ◽  
Serologic Tests ◽  
Convalescent Phase

ABSTRACT The role of serologic testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in both the clinical and public health settings, will continue to evolve as we gain increasing insight into our immune response to the virus. Here, we evaluated four high-throughput serologic tests for detection of anti-SARS-CoV-2 IgG antibodies, from Abbott Laboratories (Abbott Park, IL), Epitope Diagnostics, Inc. (San Diego, CA), Euroimmun (Lubeck, Germany), and Ortho-Clinical Diagnostics (Rochester, NY), using a panel of serially collected serum samples (n = 224) from 56 patients with confirmed coronavirus disease 2019 (COVID-19), healthy donor sera from 2018, and a cross-reactivity serum panel collected in early 2020. The sensitivities of the Abbott, Epitope, Euroimmun, and Ortho-Clinical IgG assays in convalescent-phase serum samples collected more than 14 days post-symptom onset or post-initial positive reverse transcriptase PCR (RT-PCR) result were 92.9% (78/84), 88.1% (74/84), 97.6% (82/84), and 98.8% (83/84), respectively. Among unique convalescent patients, sensitivities of the Abbott, Epitope, Euroimmun, and Ortho-Clinical anti-SARS-CoV-2 IgG assays were 97.3% (36/37), 73% (27/37), 94.6% (35/37), and 97.3% (36/37), respectively. Overall assay specificity/positive predictive values based on a 5% prevalence rate were 99.6%/92.8%, 99.6%/90.6%, 98.0%/71.2%, and 99.6%/92.5%, respectively, for the Abbott, Epitope, Euroimmun, and Ortho-Clinical IgG assays. In conclusion, we show high sensitivity in convalescent-phase sera and high specificity for the Abbott, Euroimmun, and Ortho-Clinical anti-SARS-CoV-2 IgG assays. With the unprecedented influx of commercially available serologic tests for detection of antibodies against SARS-CoV-2, it remains imperative that laboratories thoroughly evaluate such assays for accuracy prior to implementation.

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