Objectives: To evaluate and compare the performances of five commercial ELISA assays (EDI, AnshLabs, Dia.Pro, NovaTec, and Lionex) for detecting anti-SARS-CoV-2 IgG.
Methods: 70 negative control samples (collected before the COVID-19 pandemic) and samples from 101 RT-PCR-confirmed SARS-CoV-2 patients (collected at different time points from symptoms onset: ≤7, 8-14, and >14 days) were used to compare the sensitivity, specificity, agreement, positive and negative predictive values of each assay with RT-PCR. A concordance assessment between the five assays was also conducted. Cross-reactivity with other HCoV, non-HCoV respiratory viruses, non-respiratory viruses, and nuclear antigens was investigated.
Results: Lionex showed the highest specificity (98.6%, 95%CI: 92.3-99.8), followed by EDI and Dia.Pro (97.1%, 95%CI: 90.2-99.2), NovaTec (85.7%, 95%CI: 75.7-92.1), then AnshLabs (75.7%, 95%CI: 64.5-84.2). All ELISA kits cross-reacted with one anti-MERS IgG positive sample except Lionex. The sensitivity was low during the early stages of the disease but improved over time.
After 14 days from symptoms onset, Lionex and NovaTec showed the highest sensitivity at 87.9% (95%CI: 72.7-95.2) and 86.4% (95%CI: 78.5-91.7), respectively. The agreement with RT-PCR results based on Cohen’s kappa was as follows: Lionex (0.89)> NovaTec (0.70)> Dia.Pro (0.69)> AnshLabs (0.63)> EDI (0.55).
Conclusion: The Lionex ELISA, which measures antibodies solely to the S1 protein, demonstrated the best performance.
Simultaneous quantification of rituximab and eculizumab in human plasma by liquid chromatography-tandem mass spectrometry and comparison with rituximab ELISA kits
Objectives: Specific and sensitive analytical techniques to quantify therapeutic monoclonal antibodies (mAbs) are required for therapeutic drug monitoring. The quantification of mAbs has been historically performed using enzyme-linked immunosorbent assays (ELISAs), for which the limitations in terms of specificity have led to the development of alternative analytical strategies.
Methods: Here, we describe the validation of a liquid chromatography tandem mass-spectrometry (LC-MS/MS) method for the simultaneous quantification of rituximab (RTX – anti-CD20) and eculizumab (ECU – anti-C5). Sample preparation was based on our previously published method, using protein G purification and trypsin digestion.
A new specific peptide for RTX, containing an N-terminal pyroglutamine and a trypsin miss-cleavage, enables better sensitivity, while peptide of ECU was chosen thanks to an in silico trypsin digestion and the Skyline software. Full-length stable-isotope-labeled adalimumab was added to plasma samples as an internal standard. RTX in 50 human serum samples was quantified by LC-MS/MS and the concentrations obtained compared to those obtained with two commercial ELISA kits (Lisa Tracker and Promonitor).
Results: Calibration curves were linear from 1 to 200 µg.mL-1 for RTX and 5 to 200 µg.mL-1 for ECU, and within-day and between-day accuracy and precision fulfilled Food and Drug Administration validation criteria. Comparison of the LC-MS/MS method with ELISA showed a negligible bias with the Lisa Tracker kit (4%), but significant bias with the Promonitor assay (mean underestimation of 69% for the Promonitor assay).
Conclusions: This new LC-MS/MS method allows the simultaneous quantification of RTX and ECU in human samples and could be used for therapeutic drug monitoring.
Keywords: ELISA; Eculizumab; Liquid-chromatography tandem mass spectrometry; Rituximab; Therapeutic drug monitoring.
Comparison of an Immunochromatographic Assay Kit with DAS-ELISA for Large-Scale Diagnosis and Molecular Discrimination of Satsuma Dwarf Virus Collected from Citrus Orchards
Satsuma dwarf virus (SDV) seriously damages citrus production by reducing the quality and yield of fruit. To avoid contamination with SDV, mother trees are checked to be SDV-free in advance of nursery tree distribution. In this study, we compared an immunochromatographic assay (ICA) kit with double-antibody sandwich enzyme-linked immunosorbent assay (DASELISA) for large-scale diagnosis of SDV in orchardgrown trees in Shizuoka Prefecture, Japan. The two methods gave conflicting results for 11 of 1,705 samples, all of which were negative by DAS-ELISA but positive by ICA.
The samples scored as positive by either DASELISA or ICA were analyzed by reverse transcription polymerase chain reaction and all were confirmed to be positive. These results validate the use of ICA as a screening method for large-scale diagnosis. Strain discrimination revealed that 16 of 22 isolates belonged to SDV, while citrus mosaic virus (CiMV) infection only and co-infection (SDV and CiMV) were in a minority.
Objective: Glypican4 is an interesting new adipokine, which seems to play an important role in developmental processes and is potentially associated with metabolic changes in obesity and type 2 diabetes mellitus. Currently, only a few studies examined glypican4 in human blood, mainly in adults.
Design, patients and measurements: The aim of our study was to investigate glypican4 serum levels in lean, overweight, and obese children and adolescents, to unravel a possible association between glypican4 serum levels and parameters of obesity and insulin resistance.
In order to determine a suitable method for investigating glypican4 serum levels, we validated two commercially available human glypican4 ELISA kits, using serum and plasma samples of an obese, insulin-resistant patient, and a healthy control subject, a human recombinant glypican4 protein fragment and glypican4-overexpressing cell lysate.
Results: Using ELISA kit #1 we were not able to detect values above background level, apart from standard curve values. ELISA kit #2 initially seemed suitable to measure glypican4, but further validation experiments showed non-linearity of serial dilutions, no recognition of a human recombinant glypican4 protein fragment and non-linearity in the recovery of glypican4-overexpressing cell lysate.
In addition, there was a considerable decrease (approx. 68%) of measured values between two experiments, performed at different time points with aliquots of the same serum sample. Contrary to that, further experiments found sample stability not to be compromised.
Conclusions: Extensive evaluation of the performance of two commercially available ELISA kits led to the conclusion that none of them is applicable for the measurement of glypican4 in human blood samples.
Evaluation of three commercially available ELISA kits for the determination of chromogranin A
Chromogranin A (CgA) is currently the most valuable tumor biomarker for diagnostic work-up, management and follow-up of neuro-endocrine tumors (NET). The aim of our study was to compare three different commercially available CgA ELISA kits and to evaluate their analytical and clinical performance. CgA was measured with three different commercial ELISA kits on leftover sera from 40 patients: Chromoa R assay (Cis), Hu chromogranin A ELISA (Dia), and Neolisa chromogranin A (Euro). Analytical and clinical performance was evaluated by measuring precision, area under the ROC curve, sensitivity, specificity, positive and negative predictive value, correlation coefficients and Passing and Bablok regression analyses.
Precision (CV%) was acceptable for all evaluated ELISA’s (Cis 10.3%; Dia 9.8%; Euro 14.5%). The area under the curve (AUC) was comparable between the three assays (Cis 0.693; Dia 0.627; Euro 0.721). Sensitivity varied between 41.2% and 64.7%. Specificity ranged between 69.6% and 82.6%. Pairwise comparison revealed significant systematic and proportional differences when comparing Cis versus Dia (Cis = 25.30 + 1.94 Dia) and Euro versus Dia (Euro = 26.54 + 1.92 Dia).
Analytical and clinical performance was comparable for the three ELISA’s. CgA results obtained with different ELISA’s are not interchangeable. Abbreviations CgA: Chromogranin A; ELISA: Enzyme-linked immunosorbent assay; IRMA: Immunoradiometric assay; NET: Neuroendocrine tumors; PPI: Proton-pump inhibitors; RIA: Radioimmunoassay.
Goat Interleukin 10 (IL10) ELISA Kit |
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| DLR-IL10-g-48T | DL Develop | 48T | EUR 603.6 |
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Description: A sandwich quantitative ELISA assay kit for detection of Goat Interleukin 10 (IL10) in samples from serum, plasma, tissue homogenates, cell lysates, cell culture supernates or other biological fluids. |
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Goat Interleukin 10 (IL10) ELISA Kit |
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| DLR-IL10-g-96T | DL Develop | 96T | EUR 784.8 |
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Description: A sandwich quantitative ELISA assay kit for detection of Goat Interleukin 10 (IL10) in samples from serum, plasma, tissue homogenates, cell lysates, cell culture supernates or other biological fluids. |
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Human Interleukin 10 (IL10) ELISA Kit |
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| DLR-IL10-Hu-48T | DL Develop | 48T | EUR 420 |
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Description: A sandwich quantitative ELISA assay kit for detection of Human Interleukin 10 (IL10) in samples from serum, plasma, tissue homogenates, cell lysates, cell culture supernates or other biological fluids. |
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Human Interleukin 10 (IL10) ELISA Kit |
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| DLR-IL10-Hu-96T | DL Develop | 96T | EUR 532.8 |
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Description: A sandwich quantitative ELISA assay kit for detection of Human Interleukin 10 (IL10) in samples from serum, plasma, tissue homogenates, cell lysates, cell culture supernates or other biological fluids. |
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Mouse Interleukin 10 (IL10) ELISA Kit |
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| DLR-IL10-Mu-48T | DL Develop | 48T | EUR 428.4 |
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Description: A sandwich quantitative ELISA assay kit for detection of Mouse Interleukin 10 (IL10) in samples from serum, plasma, tissue homogenates, cell lysates, cell culture supernates or other biological fluids. |
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Mouse Interleukin 10 (IL10) ELISA Kit |
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| DLR-IL10-Mu-96T | DL Develop | 96T | EUR 544.8 |
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Description: A sandwich quantitative ELISA assay kit for detection of Mouse Interleukin 10 (IL10) in samples from serum, plasma, tissue homogenates, cell lysates, cell culture supernates or other biological fluids. |
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Porcine Interleukin 10 (IL10) ELISA Kit |
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| DLR-IL10-p-48T | DL Develop | 48T | EUR 591.6 |
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Description: A sandwich quantitative ELISA assay kit for detection of Porcine Interleukin 10 (IL10) in samples from serum, plasma, tissue homogenates, cell lysates, cell culture supernates or other biological fluids. |
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Porcine Interleukin 10 (IL10) ELISA Kit |
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| DLR-IL10-p-96T | DL Develop | 96T | EUR 769.2 |
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Description: A sandwich quantitative ELISA assay kit for detection of Porcine Interleukin 10 (IL10) in samples from serum, plasma, tissue homogenates, cell lysates, cell culture supernates or other biological fluids. |
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Rat Interleukin 10 (IL10) ELISA Kit |
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| DLR-IL10-Ra-48T | DL Develop | 48T | EUR 544.8 |
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Description: A sandwich quantitative ELISA assay kit for detection of Rat Interleukin 10 (IL10) in samples from serum, plasma, tissue homogenates, cell lysates, cell culture supernates or other biological fluids. |
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Rat Interleukin 10 (IL10) ELISA Kit |
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| DLR-IL10-Ra-96T | DL Develop | 96T | EUR 704.4 |
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Description: A sandwich quantitative ELISA assay kit for detection of Rat Interleukin 10 (IL10) in samples from serum, plasma, tissue homogenates, cell lysates, cell culture supernates or other biological fluids. |
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Rabbit Interleukin 10 (IL10) ELISA Kit |
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| DLR-IL10-Rb-48T | DL Develop | 48T | EUR 544.8 |
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Description: A sandwich quantitative ELISA assay kit for detection of Rabbit Interleukin 10 (IL10) in samples from serum, plasma, tissue homogenates, cell lysates, cell culture supernates or other biological fluids. |
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Rabbit Interleukin 10 (IL10) ELISA Kit |
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| DLR-IL10-Rb-96T | DL Develop | 96T | EUR 704.4 |
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Description: A sandwich quantitative ELISA assay kit for detection of Rabbit Interleukin 10 (IL10) in samples from serum, plasma, tissue homogenates, cell lysates, cell culture supernates or other biological fluids. |
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Bovine Interleukin 10 (IL10) ELISA Kit |
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| RDR-IL10-b-48Tests | Reddot Biotech | 48 Tests | EUR 619.2 |
Bovine Interleukin 10 (IL10) ELISA Kit |
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| RDR-IL10-b-96Tests | Reddot Biotech | 96 Tests | EUR 859.2 |
Canine Interleukin 10 (IL10) ELISA Kit |
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| RDR-IL10-c-48Tests | Reddot Biotech | 48 Tests | EUR 591.6 |
Canine Interleukin 10 (IL10) ELISA Kit |
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| RDR-IL10-c-96Tests | Reddot Biotech | 96 Tests | EUR 819.6 |
Chicken Interleukin 10 (IL10) ELISA Kit |
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| RDR-IL10-Ch-48Tests | Reddot Biotech | 48 Tests | EUR 564 |
Chicken Interleukin 10 (IL10) ELISA Kit |
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| RDR-IL10-Ch-96Tests | Reddot Biotech | 96 Tests | EUR 781.2 |
Equine Interleukin 10 (IL10) ELISA Kit |
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| RDR-IL10-Eq-48Tests | Reddot Biotech | 48 Tests | EUR 633.6 |
Equine Interleukin 10 (IL10) ELISA Kit |
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| RDR-IL10-Eq-96Tests | Reddot Biotech | 96 Tests | EUR 879.6 |
Goat Interleukin 10 (IL10) ELISA Kit |
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| RDR-IL10-g-48Tests | Reddot Biotech | 48 Tests | EUR 633.6 |
Goat Interleukin 10 (IL10) ELISA Kit |
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| RDR-IL10-g-96Tests | Reddot Biotech | 96 Tests | EUR 879.6 |
Human Interleukin 10 (IL10) ELISA Kit |
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| RDR-IL10-Hu-48Tests | Reddot Biotech | 48 Tests | EUR 416.4 |
Human Interleukin 10 (IL10) ELISA Kit |
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| RDR-IL10-Hu-96Tests | Reddot Biotech | 96 Tests | EUR 568.8 |