scholarly journals Heat inactivation of serum interferes with the immunoanalysis of antibodies to SARS-CoV-2

2020 ◽  
Author(s):  
Xiumei Hu ◽  
Taixue An ◽  
Bo Situ ◽  
Yuhai Hu ◽  
Zihao Ou ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
False Negative ◽  
Average Level ◽  
Heat Inactivation ◽  
Serum Antibodies ◽  
Serum Samples ◽  
Negative Results ◽  
False Negative Results ◽  
Before And After ◽  
Quantitative Fluorescence

AbstractThe detection of serum antibodies to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is emerging as a new tool for the coronavirus disease-2019 (COVID-19) diagnosis. Since many coronaviruses are sensitive to heat, heating inactivation of samples at 56 °C prior to testing is considered a possible method to reduce the risk of transmission, but the effect of heating on the measurement of SARS-CoV-2 antibodies is still unclear. By comparing the levels of SARS-CoV-2 antibodies before and after heat inactivation of serum at 56 °C for 30 minutes using a quantitative fluorescence immunochromatographic assay, we shown that heat inactivation significantly interferes with the levels of antibodies to SARS-CoV-2. The IgM levels of all the 34 serum samples (100%) from COVID-19 patients decreased by an average level of 53.56%. The IgG levels were decreased in 22 of 34 samples (64.71%) by an average level of 49.54%. Similar changes can also be observed in the non-COVID-19 diseases group (n=9). Of note, 44.12% of the detected IgM levels were dropped below the cut-off value after heating, suggesting heat inactivation can lead to false-negative results of these samples. Our results indicate that heat inactivation of serum at 56 °C for 30 minutes interferes with the immunoanalysis of antibodies to SARS-CoV-2. Heat inactivation prior to immunoanalysis is not recommended and the possibility of false-negative results should be considered if the sample was pre-inactivated by heating.

scholarly journals False negative results in the Roche assay for HDL-cholesterol

2003 ◽  
Vol 40 (5) ◽  
pp. 572-575 ◽  
Author(s):  
Andries J Bakker ◽  
Appie Zijlstra ◽  
Marten P Leemhuis
Keyword(s):  
Cardiovascular Disease ◽  
Risk Evaluation ◽  
False Negative ◽  
Hdl Cholesterol ◽  
Daily Practice ◽  
Vascular Risk ◽  
Serum Samples ◽  
Negative Results ◽  
Risk Estimates ◽  
False Negative Results

Measurement of HDL-cholesterol is important in the risk evaluation of cardiovascular disease. Recently, we encountered a 61-year-old man with a negative result for HDL-cholesterol using the Roche assay. Further analysis revealed that this patient had a monoclonal Ig type IgM κ, with an electrophoresis-based concentration of 55.8 g/L, which apparently caused the negative result for HDL-cholesterol. Analysis of serum samples from other patients with monoclonal or polyclonal hypergammaglobulinaemia revealed that false negative results in the Roche assay for HDL-cholesterol may occur incidentally. Since negative results are detected easily in the laboratory, such patients do not pose a problem in daily practice. However, it is reasonable to suppose that false low results could also be caused by monoclonal as well as polyclonal Igs. Since such false low results remain undetected, vascular risk estimates consequently are altered and unnecessary treatment might be started.

Three highly sensitive "bedside" serum and urine tests for pregnancy compared

1990 ◽  
Vol 36 (9) ◽  
pp. 1686-1688 ◽  
Author(s):  
H Christensen ◽  
H H Thyssen ◽  
O Schebye ◽  
A Berget
Keyword(s):  
Paired Comparison ◽  
False Negative ◽  
Diagnostic Sensitivity ◽  
Enzyme Linked Immunosorbent Assay ◽  
Serum Samples ◽  
Negative Results ◽  
False Negative Results ◽  
Significant Difference ◽  
Comparison Of The Results ◽  
Urine And Serum

Abstract We examined three enzyme-linked immunosorbent assay (ELISA) kits for human choriogonadotropin (hCG) (pregnancy tests) for use with urine and serum samples: the Tandem Icon II hCG Urine and Tandem Icon II hCG Serum, the NovoClone Target hCG Test, and the Abbott TestPacks hCG-urine and hCG-serum. Paired comparison of the results from each kit indicated that the NovoClone Target assay showed significantly lower diagnostic sensitivity (P less than 0.05) than did the Tandem Icon II or Abbott TestPack, both for urine and for serum samples. None of the products demonstrated any significant difference (P greater than 0.05) in diagnostic specificity, but the NovoClone Target kit showed several serious false-negative results with both urine and serum. Paired testing of urine kits vs serum kits also showed no significant differences (P greater than 0.05) in diagnostic sensitivity or specificity. We found the Abbott kits to be the most convenient to use and to read.

scholarly journals Mutations in Animal SARS-CoV-2 Induce Mismatches with the Diagnostic PCR Assays

Pathogens ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 371
Author(s):  
Ahmed Elaswad ◽  
Mohamed Fawzy
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Animal Species ◽  
False Negative ◽  
Bioinformatic Analysis ◽  
Diagnostic Pcr ◽  
Animal Host ◽  
Negative Results ◽  
False Negative Results ◽  
Pcr Assays

Recently, the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) was detected in several animal species. After transmission to animals, the virus accumulates mutations in its genome as adaptation to the new animal host progresses. Therefore, we investigated whether these mutations result in mismatches with the diagnostic PCR assays and suggested proper modifications to the oligo sequences accordingly. A comprehensive bioinformatic analysis was conducted using 28 diagnostic PCR assays and 793 publicly available SARS-CoV-2 genomes isolated from animals. Sixteen out of the investigated 28 PCR assays displayed at least one mismatch with their targets at the 0.5% threshold. Mismatches were detected in seven, two, two, and six assays targeting the ORF1ab, spike, envelope, and nucleocapsid genes, respectively. Several of these mismatches, such as the deletions and mismatches at the 3’ end of the primer or probe, are expected to negatively affect the diagnostic PCR assays resulting in false-negative results. The modifications to the oligo sequences should result in stronger template binding by the oligos, better sensitivity of the assays, and higher confidence in the result. It is necessary to monitor the targets of diagnostic PCR assays for any future mutations that may occur as the virus continues to evolve in animals.

scholarly journals Potential False-Positive and False-Negative Results for COVID-19 IgG/IgM Antibody Testing After Heat-Inactivation

2021 ◽  
Vol 7 ◽  
Author(s):  
Jie Lin ◽  
Wei Dai ◽  
Weiwei Li ◽  
Li Xiao ◽  
Tao Luo ◽  
...  
Keyword(s):  
False Negative ◽  
Antibody Detection ◽  
Heat Inactivation ◽  
Antibody Testing ◽  
Igg Antibody ◽  
Igm Antibody ◽  
Negative Results ◽  
False Negative Results ◽  
Specific Igg ◽  
Potential False Positive

Objectives: With the worldwide spread of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), various antibody detection kits have been developed to test for SARS-CoV-2– specific IgG, IgM, and total antibody. However, the use of different testing methods under various heat-inactivation conditions might affect the COVID-19 detection results.Methods: Seven different antibody detection kits produced by four manufacturers for detection of SARS-CoV-2 IgG, IgM, and total antibody were tested at Wuhan Huoshenshan Hospital, China. Most of the kits used the indirect immunity, capture, and double-antigen sandwich methods. The effects of various heat-inactivation conditions on SARS-CoV-2-specific IgG, IgM, and total antibody detection were analyzed for the different test methods.Results: Using the indirect immunity method, values for SARS-CoV-2 IgG antibody significantly increased and those for IgM antibody decreased with increasing temperature of heat-inactivation using indirect immunity method. However, values for SARS-CoV-2 IgM and total antibody showed no change when the capture and double-antigen sandwich methods were used. The changes in IgG and IgM antibody values with the indirect immunity method indicated that heat-inactivation could affect COVID-19 detection results obtained using this method. In particular, 18 (22.2%) SARS-CoV-2 IgM positive samples were detected as negative with heat-inactivation at 65°C for 30 min, and one (25%) IgG negative sample was detected as positive after heat-inactivation at 56°C for 60 min and 60°C for 30 min.Conclusions: Heat-inactivation could increase SARS-CoV-2 IgG antibody values, and decrease IgM antibody values, causing potential false-positive or false-negative results for COVID-19 antibody detection using the indirect immunity method. Thus, before conducting antibody testing, the testing platforms should be evaluated in accordance with the relevant requirements to ensure accurate COVID-19 detection results.

Sandwich dot-immunogold filtration assay (DIGFA) for specific immunodiagnosis of active neuroangiostrongyliasis

Parasitology ◽  
2020 ◽  
pp. 1-6
Author(s):  
Praphathip Eamsobhana ◽  
Anchalee Tungtrongchitr ◽  
Hoi-Sen Yong ◽  
Anchana Prasartvit ◽  
Darawan Wanachiwanawin ◽  
...  
Keyword(s):  
False Negative ◽  
Clinical Samples ◽  
Serum Samples ◽  
Serological Tests ◽  
Past Infection ◽  
Negative Results ◽  
Resource Limited ◽  
False Negative Results ◽  
Circulating Antigens ◽  
Specific Antigens

Abstract Serological tests may yield false-negative results for specific antibodies detection before or at the early seroconversion phase. Tests that detect circulating antigens of Angiostrongylus cantonensis would therefore be of value in diagnosis to distinguish current or past infection. Here, a quick, easy to perform, portable and inexpensive diagnostic device for detection of 31-kDa A. cantonensis specific antigens had been developed. This sandwich dot-immunogold filtration assay (AcDIGFAAg), for detecting active angiostrongyliasis was produced using anti-A. cantonensis polyclonal antibody dotted on the nitrocellulose membrane as a capture agent and colloidal gold-labelled anti-31 kDa A. cantonensis antibody as a detection agent. A well-defined pink dot, indicating positivity, was seen readily by naked eye within 10–15 min. The AcDIGFAAg detected A. cantonensis-specific antigens in cerebrospinal fluid samples from 4 out of 10 serologically confirmed angiostrongyliasis cases and 2 out of 5 suspected cases with negative anti-A. cantonensis antibodies. Among the 19 patient sera with A. cantonensis infection, 2 showed positive reaction by AcDIGFAAg. No positive AcDIGFAAg reaction was observed in all the serum samples with other parasitic diseases, and the healthy controls. The present ‘AcDIGFAAg’ enables rapid qualitative detection of the specific 31-kDa antigens of A. cantonensis in clinical samples with potential for application even under resource-limited settings.

scholarly journals Early Detection of Maedi-Visna (Ovine Progressive Pneumonia) Virus Seroconversion in Field Sheep Samples

2001 ◽  
Vol 13 (4) ◽  
pp. 301-307 ◽  
Author(s):  
R. Varea ◽  
E. Monleón ◽  
C. Pacheco ◽  
L. Luján ◽  
R. Bolea ◽  
...  
Keyword(s):  
Early Detection ◽  
False Negative ◽  
Field Conditions ◽  
Enzyme Linked Immunosorbent Assay ◽  
Serum Samples ◽  
Negative Results ◽  
Visna Virus ◽  
False Negative Results ◽  
Ovine Progressive Pneumonia ◽  
Antibody Levels

The aim of this work was to investigate whether an enzyme-linked immunosorbent assay (ELISA) was useful for early detection of maedi-visna virus (MVV) infection in sheep under field conditions. An ELISA based on p25 recombinant protein and a gp46 synthetic peptide was used. Sequentially obtained serum samples ( n = 1,941) were studied for 4 years. ELISA results were compared with those of the agar gel immunodiffusion (AGID) test, and results of both tests were compared with a reference result established using consensus scores for at least 2 of 3 serologic techniques (AGID, ELISA, and western blotting, which was used to resolve result discrepancies between the other 2 techniques). A total of 247 discrepancies were observed between ELISA and AGID. Of these, 131 were due to an earlier detection of 120 sera by the ELISA and 11 sera by AGID. The remaining discrepancies (116) were due to the presence of false reactions in both tests. Fewer false-negative results were found by ELISA than with AGID (6 vs. 69 sera, respectively), whereas the number of false-positive results was virtually the same for ELISA and AGID (21 vs. 20, respectively). In relation to the reference result, ELISA sensitivity and specificity were 97.8% and 98.2%, respectively, whereas values for AGID were 76.3% and 98.3%, respectively. The agreement between ELISA and the reference result was higher than that between AGID and the reference result (κ value: 0.96 and 0.77, respectively). A variation in the ELISA signal (based on optical density) was observed during the study period, suggesting different antibody levels throughout the animal's life. The ELISA was useful for detecting MVV-infected sheep in field conditions and has potential for use in control and eradication programs.

scholarly journals Falsely Decreased Human Chorionic Gonadotropin (hCG) Results Due to Increased Concentrations of the Free β Subunit and the β Core Fragment in Quantitative hCG Assays

2010 ◽  
Vol 56 (12) ◽  
pp. 1839-1844 ◽  
Author(s):  
David G Grenache ◽  
Dina N Greene ◽  
Anand S Dighe ◽  
Corinne R Fantz ◽  
Daniel Hoefner ◽  
...  
Keyword(s):  
Chorionic Gonadotropin ◽  
Human Chorionic Gonadotropin ◽  
False Negative ◽  
Normal Pregnancy ◽  
Serum Samples ◽  
Core Fragment ◽  
Negative Results ◽  
Fixed Concentration ◽  
False Negative Results ◽  
High Concentrations

BACKGROUND Earlier studies have shown that increased concentrations of certain human chorionic gonadotropin (hCG) variants can cause false-negative results in some qualitative hCG devices. The objective of this study was to determine if increased concentrations of hCGβ and hCGβ core fragment (hCGβcf) cause falsely decreased results on 9 commercially available quantitative hCG assays. METHODS Several concentrations of purified hCGβ and hCGβcf were added to 2 sets of 6 serum samples with and without a fixed concentration of intact hCG. We examined 9 widely used immunoassays to measure immunoreactive hCG. Falsely decreased results were defined as those in which the measured hCG concentration was ≤50% of expected. RESULTS High concentrations of hCGβ (≥240 000 pmol/L) produced falsely decreased hCG measurements in 2 assays known to detect this variant. Similarly, high concentrations of hCGβcf (≥63 000 pmol/L) produced falsely decreased hCG measurements in 3 assays that do not detect purified hCGβcf. Two assays were identified that detected both hCGβ and hCGβcf, and neither produced falsely decreased results in the presence of high concentrations of these variants. CONCLUSIONS Extremely high concentrations of hCG variants can cause falsely decreased results in certain quantitative hCG assays. Of the 9 assays examined, none exhibited falsely decreased results in the presence of hCGβ concentrations typically associated with hCGβ-producing malignancies. Two assays exhibited decreased (>50%) hCG results in the presence of hCGβcf concentrations found during normal pregnancy.

Coagulation Testing Gone Awry; Effect of Direct Oral Anticoagulant (DOAC) Removal on Lupus Anticoagulant Assays

2020 ◽  
Vol 154 (Supplement_1) ◽  
pp. S11-S11
Author(s):  
Daniel Casa ◽  
Morayma Reyes Gil
Keyword(s):  
Lupus Anticoagulant ◽  
Oral Anticoagulants ◽  
Direct Oral Anticoagulants ◽  
Plasma Concentrations ◽  
False Negative ◽  
Plasma Samples ◽  
Negative Results ◽  
False Negative Results ◽  
Increased Risk ◽  
Before And After

Abstract Background Direct oral anticoagulants (DOACs) such as apixaban and rivaroxaban are widely used to treat those with or at risk for thromboembolic disease. However, DOACs have been shown to interfere with coagulation assays making their interpretations challenging. Importantly, lupus anticoagulant (LA) assays using the dilute Russell Viper Venom Time (dRVVT) to screen for patients at increased risk of thrombosis are particularly affected by DOACs leading to inaccurate results. DOAC removal agents are available to improve dRVVT specificity for LA and eliminate assay interferences. Aims To evaluate the performance of DOAC-Remove to accurately measure LA in patient plasma. Methods 10 LA positive and 10 LA negative samples without DOAC as well as normal pool plasma (NPP) were used as controls. We assessed 64 patient plasma samples including 39 patients on apixaban and 25 patients on rivaroxaban (anticoagulation was confirmed by chart review). LA testing by dRVVT was performed using Staclot® DRVV Screen and Staclot® DRVV Confirm reagents on STA R Max analyzer. DRVVT testing was performed before and after DOAC removal (DOAC-Remove, Aniara). DOAC plasma concentrations were measured using STA Liquid Anti-Xa assay. Acceptable DOAC removal was defined as an anti Xa level <0.03 IU/mL. Positive LA was defined as a screen ratio and mix ratio greater than 1.15. Results Positive and negative samples without DOAC remained the same after DOAC removal treatment. Factor levels in NPP were not affected by DOAC removal treatment. DOAC removal resulted in shortening of the dRVVT in 91% of the samples. Surprisingly, 6 cases showed prolongation in the dRVVT after DOAC removal. Before DOAC removal, 47 cases (24 apixaban and 23 rivaroxaban) tested positive and 17 tested negative (15 apixaban and 2 rivaroxaban). Following DOAC removal, 28 cases tested positive and 36 tested negative. As expected, many samples of patients on DOAC were found to be falsely positive (27/64; 15 on apixaban and 12 on rivaroxaban). Interestingly, 8 of 64 tests were found to be falsely negative. Of the 8 samples that were falsely negative, 7 were on apixaban and 1 on rivaroxaban. 9 samples that were negative before DOAC removal remained negative after DOAC removal, and 20 tests that were positive before DOAC removal remained positive after DOAC removal for a total of 29 results (45%) that remained unchanged. It was found that DOACs caused inaccurate results in 55% of cases. Conclusions Our study was able to demonstrate the effectiveness of DOAC-Remove to eliminate DOACs from patient plasma and provide accurate LA results. DOAC interference on LA assays predictably creates many false positive results, however, presence of DOACs can produce false negative results as well, underlying the importance of pretest screening for presence of anticoagulants in plasma samples.

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