Temporal Course of SARS-CoV-2 Antibody Positivity in Patients with COVID-19 following the First Clinical Presentation

Knowledge of the sensitivities of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody tests beyond 35 days after the clinical onset of COVID-19 is insufficient. We aimed to describe positivity rate of SARS-CoV-2 assays employing three different measurement principles over a prolonged period. Two hundred sixty-eight samples from 180 symptomatic patients with COVID-19 and a reverse transcription polymerase chain reaction (RT-PCR) test followed by serological investigation of SARS-CoV-2 antibodies were included. We conducted three chemiluminescence (including electrochemiluminescence assay (ECLIA)), four enzyme-linked immunosorbent assay (ELISA), and one lateral flow immunoassay (LFIA) test formats. Positivity rates, as well as positive (PPVs) and negative predictive values (NPVs), were calculated for each week after the first clinical presentation for COVID-19. Furthermore, combinations of tests were assessed within an orthogonal testing approach employing two independent assays and predictive values were calculated. Heat maps were constructed to graphically illustrate operational test characteristics. During a follow-up period of more than 9 weeks, chemiluminescence assays and one ELISA IgG test showed stable positivity rates after the third week. With the exception of ECLIA, the PPVs of the other chemiluminescence assays were ≥95% for COVID-19 only after the second week. ELISA and LFIA had somewhat lower PPVs. IgM exhibited insufficient predictive characteristics. An orthogonal testing approach provided PPVs ≥ 95 % for patients with a moderate pretest probability (e.g., symptomatic patients), even for tests with a low single test performance. After the second week, NPVs of all but IgM assays were ≥95% for patients with low to moderate pretest probability. The confirmation of negative results using an orthogonal algorithm with another assay provided lower NPVs than the single assays. When interpreting results from SARS-CoV-2 tests, the pretest probability, time of blood draw, and assay characteristics must be carefully considered. An orthogonal testing approach increases the accuracy of positive, but not negative, predictions.

Download Full-text

Temporal course of SARS-CoV-2 antibody positivity in patients with COVID-19 following the first clinical presentation

10.1101/2020.10.17.20214445 ◽

2020 ◽

Cited By ~ 1

Author(s):

Martin Risch ◽

Myriam Weber ◽

Sarah Thiel ◽

Kirsten Grossmann ◽

Nadia Wohlwend ◽

...

Keyword(s):

Test Performance ◽

Clinical Presentation ◽

Pretest Probability ◽

Enzyme Linked Immunosorbent Assay ◽

Blood Draw ◽

Predictive Values ◽

Negative Results ◽

Clinical Onset ◽

Operational Test ◽

Testing Approach

AbstractKnowledge of the sensitivities of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antibody tests beyond 35 days after the clinical onset of COVID-19 is insufficient. We aimed to describe positivity rate of SARS-CoV-2 assays employing three different measurement principles over a prolonged period. Two hundred sixty-eight samples from 180 symptomatic patients with COVID-19 and a reverse transcription polymerase chain reaction (RT-PCR) test followed by serological investigation of SARS-CoV-2 antibodies were included.. We conducted three chemiluminescence (including electrochemiluminscence, ECLIA), four enzyme linked immunosorbent assay (ELISA), and one lateral flow immunoassay (LFIA) test formats. Positivity rates, as well as positive (PPV) and negative predictive values (NPV) were calculated for each week after the first clinical presentation for COVID-19. Furthermore, combinations of tests were assessed within an orthogonal testing approach employing two independent assays and predictive values were calculated. Heat maps were constructed to graphically illustrate operational test characteristics. During a follow-up period of more than 9 weeks, chemiluminescence assays and one ELISA IgG test showed stable positivity rates after the third week. With the exception of ECLIA, the PPVs of the other chemiluminescence assays were ≥95% for COVID-19 only after the second week. ELISA and LFIA had somewhat lower PPVs. IgM exhibited insufficient predictive characteristics. An orthogonal testing approach provided PPVs ≥95% for patients with a moderate pretest probability (e.g., symptomatic patients), even for tests with a low single test performance. After the second week, NPVs of all but IgM assays were ≥95% for patients with low to moderate pretest probability. The confirmation of negative results using an orthogonal algorithm with another assay provided lower NPVs than the single assays. When interpreting results from SARS-CoV-2 tests, the pretest probability, time of blood draw and assay characteristics must be carefully considered. An orthogonal testing approach increases the accuracy of positive, but not negative, predictions.

Download Full-text

Evaluation of anti-SARS-CoV-2 antibody testing in asymptomatic or mild COVID-19 patients in outbreak on a cruise ship

10.1101/2021.03.10.21253064 ◽

2021 ◽

Author(s):

Norihito Kaku ◽

Fumitaka Nishimura ◽

Yui Shigeishi ◽

Rina Tachiki ◽

Hironori Sakai ◽

...

Keyword(s):

Genetic Test ◽

False Negative ◽

Enzyme Linked Immunosorbent Assay ◽

Cruise Ship ◽

Igg Antibodies ◽

Antibody Testing ◽

Predictive Values ◽

Blood Samples ◽

Negative Results ◽

Genetic Test Results

AbstractBackgroundA few studies on antibody testing have focused on asymptomatic or mild coronavirus disease 2019 (COVID-19) patients with low initial anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody responses. Anti-SARS-CoV-2 antibody-testing performance was evaluated using blood samples from asymptomatic or mild COVID-19 patients.MethodsBlood samples were collected from 143 COVID-19 patients during an outbreak on a cruise ship 3 weeks after diagnosis. Simultaneously, a second SARS-CoV-2 genetic test was performed. Samples stored before the COVID-19 pandemic were also used to evaluate the lateral flow immunochromatographic assay (LFA) and electrochemiluminescence immunoassay (ECLIA). Titers of anti-SARS-CoV-2 IgM and IgG antibodies against the nucleocapsid and spike proteins were measured using the enzyme-linked immunosorbent assay to compare false-negative- with positive-result samples.ResultsSensitivity, specificity, positive-predictive, and negative-predictive values of LFA-detected IgM antibodies were 0.231, 1.000, 1.000, and 0.613, respectively; those of LFA-detected IgG antibodies were 0.483, 0.989, 0.972, and 0.601, respectively; and those of ECLIA-detected total antibodies were 0.783, 1.000, 1.000, and 0.848, respectively. IgM-, IgG-, and total-antibody positivity rates in the patients with negative results from the second genetic testing were 22.9%, 47.6%, and 72.4%, respectively. All antibody titers, especially those of the IgG antibody against nucleocapsid protein, were significantly lower in blood samples with false-negative results than in those with positive results.ConclusionsThese findings suggest that anti-SARS-CoV-2 antibody testing has lower performance in asymptomatic or mild COVID-19 patients than required in the guidelines, and situations in which it is useful are limited.Key pointsAnti-SARS-CoV-2 antibody testing in asymptomatic or mild COVID-19 patients is lower than the required clinical sensitivity, although it may be useful in patients at 3–4 weeks after symptom onset but with negative SARS-CoV-2 genetic test results.

Download Full-text

Performance of Ag-ELISA in the diagnosis of Taenia solium cysticercosis in naturally infected pigs in Tanzania

Parasites & Vectors ◽

10.1186/s13071-020-04416-4 ◽

2020 ◽

Vol 13 (1) ◽

Author(s):

Mwemezi L. Kabululu ◽

Maria V. Johansen ◽

James E. D. Mlangwa ◽

Ernatus M. Mkupasi ◽

Uffe C. Braae ◽

...

Keyword(s):

Test Performance ◽

Late Onset ◽

Taenia Solium ◽

Elisa Test ◽

Diagnostic Tools ◽

Enzyme Linked Immunosorbent Assay ◽

Likelihood Ratios ◽

Taenia Hydatigena ◽

Predictive Values ◽

Circulating Antigens

Abstract Background Taenia solium is a zoonotic parasite responsible for neurocysticercosis—a major cause of late-onset acquired epilepsy in humans. Lack of affordable, specific and sensitive diagnostic tools hampers control of the parasite. This study assessed the performance of an antigen detection enzyme-linked immunosorbent assay (Ag-ELISA) in the diagnosis of viable T. solium cysticercosis in naturally infected slaughter-age pigs in an endemic area in Tanzania. Methods A total of 350 pigs were bled before they were slaughtered and their carcases examined. Serum was analyzed for circulating antigens by using a monoclonal antibody-based B158/B60 Ag-ELISA. Each carcase was examined for the presence of Taenia hydatigena cysticerci and half carcase musculature together with the whole brain, head muscles, tongue, heart and diaphragm were sliced with fine cuts (< 0.5 cm) to reveal and enumerate T. solium cysticerci. Half carcase dissection can detect at least 84% of infected pigs. Prevalence and their 95% confidence intervals (CI) were calculated in Stata 12. Sensitivity, specificity, predictive values and likelihood ratios were determined. Results Twenty–nine pigs (8.3%, 95% CI: 5.6–11.7%) had viable T. solium cysticerci while 11 pigs had T. hydatigena cysticerci (3.1%, 95% CI: 1.6–5.5%). No co-infection was observed. Sixty-eight pigs (19.4%, 95% CI: 15.4–20%) tested positive on Ag-ELISA; of these, 24 had T. solium cysticerci and 7 had T. hydatigena cysticerci. Sensitivity and specificity were determined to be 82.7% and 86.3%, respectively. Positive and negative predictive values were 35.2% and 98.2%, respectively. Likelihood ratios for positive and negative Ag-ELISA test results were 6.0 and 0.2, respectively. There was a significant positive correlation between the titre of circulating antigens and intensity of T. solium cysticerci (r(348) = 0.63, P < 0.001). Conclusions The Ag-ELISA test characteristics reported in this study indicate that the test is more reliable in ruling out T. solium cysticercosis in pigs, than in confirming it. Hence, a negative result will almost certainly indicate that a pig has no infection, but a positive result should always be interpreted with caution. Estimates of T. solium prevalence based on Ag-ELISA results should, therefore, be adjusted for test performance characteristics and occurrence of T. hydatigena.

Download Full-text

Performance of Serology Assays for Diagnosing Celiac Disease in a Clinical Setting

Clinical and Vaccine Immunology ◽

10.1128/cvi.00205-09 ◽

2009 ◽

Vol 16 (11) ◽

pp. 1576-1582 ◽

Cited By ~ 26

Author(s):

Miriam Parizade ◽

Yoram Bujanover ◽

Batya Weiss ◽

Vered Nachmias ◽

Bracha Shainberg

Keyword(s):

Celiac Disease ◽

High Risk ◽

Clinical Setting ◽

Test Performance ◽

Large Scale ◽

Tissue Transglutaminase ◽

Enzyme Linked Immunosorbent Assay ◽

Predictive Values ◽

Chemiluminescence Assay ◽

Cutoff Points

ABSTRACT Diagnosis of celiac disease frequently depends upon serology assays. We set out to prospectively assess the diagnostic value of five serology tests: an enzyme-linked immunosorbent assay (ELISA) for tissue transglutaminase (tTG)-immunoglobulin A (IgA) and tTG-IgG, a chemiluminescence assay for tTG-IgA, an ELISA for deamidated gliadin peptide (DGP) IgG and IgA screening, and detection of endomysial antibodies (Abs) by indirect immunofluorescence. One hundred sixteen children at high risk for developing celiac disease were evaluated clinically and underwent small bowel biopsies and blood serology tests. We examined differences between younger and older children in terms of clinical presentation, test performance, and the ability of high Ab levels to correctly predict diagnosis of celiac disease. Celiac disease was diagnosed for 85 (73%) children. No significant clinical differences were observed between the biopsy-positive and biopsy-negative groups. Children ≤3 years of age revealed higher concentrations of tTG-IgA and DGP Abs than children >3 years old (P = 0.017 and 0.007, respectively). High Ab concentrations were predictive of villous atrophies, with sensitivities ranging from 92.8% to 97.9%, depending on the assay and the cutoff points applied. Sensitivities, specificities, positive predictive values, and negative predictive values varied among assays and improved after correction for best cutoff points. Assay specificities obtained in the clinical setting were lower than expected. The new tTG-IgA chemiluminescence assay demonstrated high throughput but low specificity (74.2%). The tTG-IgA ELISA exhibited the highest test efficiency, and the tTG-IgA chemiluminescence assay was suitable for large-scale screening, with reduced specificity. High concentrations of celiac disease-specific Abs bring into question the need for performance of biopsies on children at high risk.

Download Full-text

Performance of anti-SARS-CoV-2 antibody testing in asymptomatic or mild COVID-19 patients: A retrospective study in outbreak on a cruise ship

PLoS ONE ◽

10.1371/journal.pone.0257452 ◽

2021 ◽

Vol 16 (9) ◽

pp. e0257452

Author(s):

Norihito Kaku ◽

Fumitaka Nishimura ◽

Yui Shigeishi ◽

Rina Tachiki ◽

Hironori Sakai ◽

...

Keyword(s):

False Negative ◽

Enzyme Linked Immunosorbent Assay ◽

Cruise Ship ◽

Igg Antibodies ◽

Antibody Testing ◽

Predictive Values ◽

Blood Samples ◽

Negative Results ◽

Sensitivity Specificity

Objectives A few studies on antibody testing have focused on asymptomatic or mild coronavirus disease 2019 (COVID-19) patients with low initial anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody responses. Anti-SARS-CoV-2 antibody-testing performance was evaluated using blood samples from asymptomatic or mild COVID-19 patients. Methods Blood samples were collected from 143 COVID-19 patients during an outbreak on a cruise ship 3 weeks after diagnosis. Simultaneously, a follow-up SARS-CoV-2 genetic test was performed. Samples stored before the COVID-19 pandemic were also used to evaluate the lateral flow immunochromatographic assay (LFA) and electrochemiluminescence immunoassay (ECLIA). Titers of anti-SARS-CoV-2 IgM and IgG antibodies against the nucleocapsid and spike proteins were measured using the enzyme-linked immunosorbent assay to confirm which antibodies were influenced on LFA- and ECLIA- false-negative result in crew-member samples. Results Sensitivity, specificity, positive-predictive, and negative-predictive values of LFA-detected IgM antibodies were 0.231, 1.000, 1.000, and 0.613, respectively; those of LFA-detected IgG antibodies were 0.483, 0.989, 0.972, and 0.601, respectively; and those of ECLIA-detected total antibodies were 0.783, 1.000, 1.000, and 0.848, respectively. All antibody titers measured using ELISA were significantly lower in blood samples with negative results than in those with positive results in both LFA and ECLIA. In the patients with negative results from the follow-up genetic testing, IgM-, IgG-, and total-antibody positivity rates were 22.9%, 47.6%, and 72.4%, respectively. Conclusions These findings suggest that anti-SARS-CoV-2 antibody testing has lower performance in asymptomatic or mild COVID-19 patients than required in the guidelines.

Download Full-text

IgA anti-gliadin antibodies in adult celiac disease

Clinical Chemistry ◽

10.1093/clinchem/37.5.647 ◽

1991 ◽

Vol 37 (5) ◽

pp. 647-650 ◽

Cited By ~ 9

Author(s):

P G Hill ◽

S P Thompson ◽

G K Holmes

Keyword(s):

Celiac Disease ◽

Normal Subjects ◽

Enzyme Linked Immunosorbent Assay ◽

Control Group ◽

Dietary Compliance ◽

Predictive Values ◽

Negative Results ◽

Objective Evidence ◽

Adult Celiac Disease ◽

Significant Difference

Abstract We have improved the enzyme-linked immunosorbent assay for IgA-class antibodies to gliadin in serum by evaluating earlier publications. We also assess the value of measuring these antibodies when screening for adult celiac disease and monitoring dietary compliance. Of 61 adults with untreated celiac disease, 57 had abnormal results, giving a sensitivity for the test of 0.93. Patients (n = 283) attending a gastroenterology clinic formed the control group. The predictive values of positive results and negative results were 50% and 99.7%, respectively, indicating that the test has a role in helping select those subjects in whom small bowel biopsy is indicated. Adults with celiac disease, after two years on a strict gluten-free diet, and normal subjects showed no significant difference in serum IgA-class anti-gliadin antibody concentrations. The test thus provides objective evidence of dietary compliance in addition to its role as a screening test.

Download Full-text

Sensitivity, Specificity, and Predictive Values of ThreeSalmonella Rapid Detection Kits Using Fresh and Frozen Poultry Environmental Samples versus Those of Standard Plating

Applied and Environmental Microbiology ◽

10.1128/aem.65.3.1055-1060.1999 ◽

1999 ◽

Vol 65 (3) ◽

pp. 1055-1060 ◽

Cited By ~ 30

Author(s):

Melissa O. Peplow ◽

Maria Correa-Prisant ◽

Martha E. Stebbins ◽

Frank Jones ◽

Peter Davies

Keyword(s):

Rapid Detection ◽

Environmental Samples ◽

False Negative ◽

Food Samples ◽

Detection Methods ◽

Enzyme Linked Immunosorbent Assay ◽

Culture Methods ◽

Predictive Values ◽

Negative Results ◽

Rapid Tests

ABSTRACT To reduce human exposure to Salmonella spp. in poultry products, broiler chicken flocks have been tested by culture methods. Since the standard techniques may take 3 to 5 days, rapid detection methods have been developed. In this study we tested the performance of three rapid tests originally developed for food samples by using environmental samples obtained from poultry houses. These rapid tests were Reveal, an enzyme-linked immunosorbent assay from Neogen Corp.; BIND, a bacterial ice nucleation detection method from Idetek Corp.; and a filter monitor method from Future Medical Technologies, Inc. For the standard culture, brilliant green with novabiocin and xylose–lysine–tergitol-4 agar were used for presumptive identification, and identities were confirmed by using poly-O antisera. Environmental samples were collected from farms belonging to an integrated poultry company prior to chick placement and 1 week before slaughter. Sensitivities, specificities, and predictive values with 95% confidence intervals were calculated. Statistical differences were determined by using McNemar’s chi square test. The sensitivities of the different tests were not stable, varying widely between sample times, and were affected by freezing of the samples. All of the rapid tests had low sensitivities, which led to many false-negative results. All tests were able to detect Salmonella spp. at a concentration of 10 CFU/ml in at least one of four trials. The BIND and Reveal tests were simple to use with multiple samples and reduced laboratory time by up to 1 day. Based on our results, we do not recommend that any of these rapid tests, in their present state of development, be utilized with environmental samples collected with drag swabs.

Download Full-text

Evaluation of Recombinant Proteins of Burkholderia mallei for Serodiagnosis of Glanders

Clinical and Vaccine Immunology ◽

10.1128/cvi.00137-12 ◽

2012 ◽

Vol 19 (8) ◽

pp. 1193-1198 ◽

Cited By ~ 11

Author(s):

Vijai Pal ◽

Subodh Kumar ◽

Praveen Malik ◽

Ganga Prasad Rai

Keyword(s):

Sensitivity And Specificity ◽

Recombinant Proteins ◽

False Negative ◽

Enzyme Linked Immunosorbent Assay ◽

Burkholderia Mallei ◽

Content Type ◽

Whole Cells ◽

Negative Results ◽

Elisa Format ◽

Low Sensitivity

ABSTRACTGlanders is a contagious disease caused by the Gram-negative bacillusBurkholderia mallei. The number of equine glanders outbreaks has increased steadily during the last decade. The disease must be reported to the Office International des Epizooties, Paris, France. Glanders serodiagnosis is hampered by the considerable number of false positives and negatives of the internationally prescribed tests. The major problem leading to the low sensitivity and specificity of the complement fixation test (CFT) and enzyme-linked immunosorbent assay (ELISA) has been linked to the test antigens currently used, i.e., crude preparations of whole cells. False-positive results obtained from other diagnostic tests utilizing crude antigens lead to financial losses to animal owners, and false-negative results can turn a risk into a possible threat. In this study, we report on the identification of diagnostic targets using bioinformatics tools for serodiagnosis of glanders. The identified gene sequences were cloned and expressed as recombinant proteins. The purified recombinant proteins ofB. malleiwere used in an indirect ELISA format for serodiagnosis of glanders. Two recombinant proteins, 0375H and 0375TH, exhibited 100% sensitivity and specificity for glanders diagnosis. The proteins also did not cross-react with sera from patients with the closely related disease melioidosis. The results of this investigation highlight the potential of recombinant 0375H and 0375TH proteins in specific and sensitive diagnosis of glanders.

Download Full-text

High-throughput quantitation of SARS-CoV-2 antibodies in a single-dilution homogeneous assay

Scientific Reports ◽

10.1038/s41598-021-91300-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Markus H. Kainulainen ◽

Eric Bergeron ◽

Payel Chatterjee ◽

Asheley P. Chapman ◽

Joo Lee ◽

...

Keyword(s):

Enzyme Linked Immunosorbent Assay ◽

Specific Antibodies ◽

Negative Results ◽

A Value ◽

Elisa Testing ◽

The World ◽

Antibody Titers ◽

Qualitative Assay ◽

Homogeneous Assay ◽

Asymptomatic Infections

AbstractSARS-CoV-2 emerged in late 2019 and has since spread around the world, causing a pandemic of the respiratory disease COVID-19. Detecting antibodies against the virus is an essential tool for tracking infections and developing vaccines. Such tests, primarily utilizing the enzyme-linked immunosorbent assay (ELISA) principle, can be either qualitative (reporting positive/negative results) or quantitative (reporting a value representing the quantity of specific antibodies). Quantitation is vital for determining stability or decline of antibody titers in convalescence, efficacy of different vaccination regimens, and detection of asymptomatic infections. Quantitation typically requires two-step ELISA testing, in which samples are first screened in a qualitative assay and positive samples are subsequently analyzed as a dilution series. To overcome the throughput limitations of this approach, we developed a simpler and faster system that is highly automatable and achieves quantitation in a single-dilution screening format with sensitivity and specificity comparable to those of ELISA.

Download Full-text

Investigation of the rapid immunochromatographic test performance in the diagnosis of syphilis; comparison of four serological methods

LaboratoriumsMedizin ◽

10.1515/labmed-2019-0012 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Huseyin Agah Terzi ◽

Ozlem Aydemir ◽

Engin Karakece ◽

Huseyin Hatipoglu ◽

Mehmet Olmez ◽

...

Keyword(s):

Test Performance ◽

Gold Standard ◽

Treponema Pallidum ◽

Rapid Test ◽

Immunochromatographic Test ◽

Rapid Plasma Reagin ◽

Serum Samples ◽

Hemagglutination Assay ◽

Predictive Values ◽

Sensitivity Specificity

AbstractObjectivesTo test the performance of the newly available rapid test for syphilis, we compared it with Treponema pallidum hemagglutination assay (TPHA). Additionally, we investigated the performance of rapid plasma reagin (RPR) and chemiluminescence microparticle immunoassays (CMIA) at our laboratory using TPHA as a gold standard.MethodsThe serum samples of 595 patients with the pre-diagnosis of syphilis were studied by four serological methods. The sensitivity, specificity, and predictive values of RPR, CMIA, and syphilis rapid test were assessed by utilizing TPHA as a gold standard for the diagnosis of syphilis.ResultsOf the patients, 6.2% (37/595) had positive RPR, 5.5% (33/595) had positive CMIA, 5.5% (33/595) had a positive rapid immunochromatographic method and 5% (30/595) had positive TPHA. When TPHA results were taken as the reference, the sensitivity of the rapid test for syphilis was 100%, the specificity was 99.5%, PPV was 90.9%, and NPV was 100.0%.ConclusionsIt was observed that the rapid test for syphilis used in the study was quite successful, its cost was appropriate, and the test was very fast and easy to apply. At the same time, the agreement between syphilis rapid test and TPHA was found to be excellent.

Download Full-text