Performance Evaluation of the BZ COVID-19 Neutralizing Antibody Test for the Culture-Free and Rapid Detection of SARS-CoV-2 Neutralizing Antibodies

Rapid and accurate measurement of SARS-CoV-2 neutralizing antibodies (nAbs) can aid in understanding the development of immunity against COVID-19. This study evaluated the diagnostic performance of a rapid SARS-CoV-2 nAb detection test called the BZ COVID-19 nAb test BZ-nAb (BZ-nAb; BioZentech). Using the 90% plaque-reduction neutralization test (PRNT-90) as a reference, 104 serum specimens collected from COVID-19-positive and -negative patients were grouped into 40 PRNT-90-positive and 64 PRNT-90-negative specimens. The performance of the BZ-nAb was compared with that of the cPass surrogate virus neutralization test (cPass sVNT; Genscript). The BZ-nAb showed a sensitivity ranging from 92.5%–95.0% and specificity ranging from 96.9%–100%, whereas cPass sVNT showed a sensitivity of 100% (95% confidence interval (CI) 90.5%–100%) and specificity of 98.4% (95% CI, 91.6%–100%). The dilution factor obtained with PRNT-90 showed a stronger correlation with the percent inhibition of cPass sVNT (r = 0.8660, p < 0.001) compared with the test and control line ratio (T/C ratio) of the BZ-nAb (r = −0.7089, p < 0.001). An almost perfect agreement was seen between the BZ-nAb and cPass sVNT results, with a strong negative correlation between the BZ-nAb T/C ratio and cPass sVNT percent inhibition (r = −0.8022, p < 0.001). In conclusion, the diagnostic performance of the BZ-nAb was comparable to that of the cPass sVNT, although the BZ-nAb had a slightly lower sensitivity.

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Effect of a booster-dose of rabies vaccine on the duration of virus neutralizing antibody titers in bovines

Revista da Sociedade Brasileira de Medicina Tropical ◽

10.1590/s0037-86821998000400006 ◽

1998 ◽

Vol 31 (4) ◽

pp. 367-371 ◽

Cited By ~ 5

Author(s):

Avelino Albas ◽

Paulo Eduardo Pardo ◽

Albério Antonio Barros Gomes ◽

Fernanda Bernardi ◽

Fumio Honma Ito

Keyword(s):

Immune Response ◽

Neutralizing Antibodies ◽

Booster Dose ◽

Neutralization Test ◽

Neutralizing Antibody ◽

Rabies Vaccine ◽

Western Region ◽

Humoral Immune ◽

Paulo State ◽

Antibody Titers

Humoral immune response using inactivated rabies vaccine was studied in 35 nelore cross-bred bovines of western region of São Paulo state. Ninety days after vaccination, 13 (92.8%) animals presented titers 30.5IU/ml, through mouse neutralization test. After 180 days, 9 (64.3%) sera showed titers 30.5IU/ml, after 270 days, only one (7.1%) showed a titer of 0.51IU/ml, and after 360 days, all animals showed titers < 0.5IU/ml. Group of animals receiving booster dose 30 days after vaccination presented, two months after, all with titers > 0.5IU/ml. At 180 days, 17 (80.9%) sera presented titers > 0.5IU/ml; at 270 days, 15 (71.4%), with titers 30.5IU/ml and at 360 days, 4 (19.0%), with titers 30.5IU/ml. Booster-dose ensured high levels of neutralizing antibodies for at least three months, and 240 days after revaccination, 71.4% of animals were found with titers 30.5IU/ml.

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Diagnostic performance of a commercial ELISA used as a complementary test for bovine tuberculosis in two bovine herds with different disease status

Arquivo Brasileiro de Medicina Veterinária e Zootecnia ◽

10.1590/1678-4162-11071 ◽

2020 ◽

Vol 72 (1) ◽

pp. 1-8

Author(s):

P.M. Soares Filho ◽

A.K. Ramalho ◽

A.M. Silva ◽

M.A. Issa ◽

P.M.P.C. Mota ◽

...

Keyword(s):

Bovine Tuberculosis ◽

Diagnostic Performance ◽

Latent Class ◽

Serological Test ◽

Antibody Test ◽

Latent Class Models ◽

Lower Sensitivity ◽

Kappa Index ◽

Serological Tests ◽

Test Kit

ABSTRACT Bovine tuberculosis is a worldwide spread zoonotic disease. Intradermal tuberculinizations are the most used diagnostic tests in the world. Serological tests can be an ancillary diagnosis for bovine tuberculosis. The objective of this study was to evaluate the diagnostic performance of the ELISA Mycobacterium Bovis Antibody Test Kit IDEXX ™ in infected herds, which were in different disease control stages. One hundred and twenty animals from two dairy herds of Minas Gerais state, Brazil, were subjected to the ELISA serological test and the comparative cervical tuberculin test (CCT). Diagnostic test parameters were estimated using Bayesian latent class models and concordance between tests estimated by the frequentist approach. The ELISA test presented lower sensitivity than CCT in both herds. Its sensitivity was higher in the herd in sanitation process. Specificity estimates were above 95% in both herds. Kappa index indicated low concordance or even disagreement between tests. According to the results, the ELISA IDEXX should not be used as substitution for CCT. The tests must not be associated in series. Parallel association increased diagnostic sensitivity in the herd which was in the process of sanitation.

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Detection of neutralizing antibodies against SARS-CoV-2 by using a commercial surrogate virus neutralization ELISA: can it substitute the classical neutralization test?

10.1101/2021.10.12.21264881 ◽

2021 ◽

Author(s):

Natalie E Hofmann ◽

Marica Grossegesse ◽

Markus Neumann ◽

Lars Schaade ◽

Andreas Nitsche

Keyword(s):

Neutralizing Antibodies ◽

Diagnostic Performance ◽

Neutralization Test ◽

Virus Neutralization ◽

Serum Samples ◽

Population Immunity ◽

Vaccine Trials ◽

Binding Inhibition ◽

Antibody Titers ◽

High Throughput Detection

Background: High-throughput detection of neutralizing antibodies against SARS-CoV-2 presents a valuable tool for vaccine trials or investigations of population immunity. We evaluate the performance of the first commercial surrogate virus neutralization test (sVNT, GenScript Biotech) against SARS-CoV-2 plaque reduction neutralization test (PRNT) in convalescent and vaccinated individuals. We compare it to five other ELISAs, two of which are designed to detect neutralizing antibodies. Results: In 491 pre-vaccination serum samples, sVNT missed 23.6% of PRNT-positive samples when using the manufacturer-recommended cutoff of 30% binding inhibition. Introducing a equivocal area between 15 and 35% maximized sensitivity and specificity against PRNT to 72.8-93.1 % and 73.5-97.6%, respectively. The overall diagnostic performance of the other ELISAs for neutralizing antibodies was below that of sVNT. Vaccinated individuals exhibited higher antibody titers by PRNT (median 119.8, IQR 56.7-160) and binding inhibition by sVNT (median 95.7, IQR 88.1-96.8) than convalescent patients (median 49.1, IQR 20-62; median 52.9, IQR 31.2-76.2). Conclusion: GenScript sVNT is suitable to screen for SARS-CoV-2-neutralizing antibodies; however, to obtain accurate results, confirmatory testing by PRNT in a equivocal area is required. This equivocal area may require adaptation for use in vaccinated individuals, due to higher antibody titers.

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Evaluation of high-throughput SARS-CoV-2 serological assays in a longitudinal cohort of mild COVID-19 patients: sensitivity, specificity and association with virus neutralization test

10.1101/2020.09.30.20194290 ◽

2020 ◽

Author(s):

Antonin Bal ◽

Bruno Pozzetto ◽

Mary-Anne Trabaud ◽

Vanessa Escuret ◽

Muriel Rabilloud ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Healthcare Workers ◽

Neutralization Test ◽

Neutralizing Antibody ◽

Virus Neutralization Test ◽

Virus Neutralization ◽

Serological Tests ◽

Course Of Disease ◽

Antibody Titers ◽

Sensitivity Specificity

BackgroundThe association between SARS-CoV-2 commercial serological assays and virus neutralization test (VNT) has been poorly explored in mild COVID-19 patients.MethodsA total of 439 serum specimens were longitudinally collected from 76 healthcare workers with RT-PCR-confirmed COVID-19. The sensitivity (determined weekly) of nine commercial serological assays were evaluated. Specificity was assessed using 69 pre-pandemic sera. Correlation, agreement and concordance with the VNT were also assessed on a subset of 170 samples. Area under the ROC curve (AUC) was estimated at several neutralizing antibody titers.ResultsThe Wantai Total Ab assay targeting the receptor binding domain (RBD) within the S protein presented the best sensitivity at different times during the course of disease. The specificity was greater than 95% for all tests except for the Euroimmun IgA assay. The overall agreement with the presence of neutralizing antibodies ranged from 62.2% (95%CI; 56.0-68.1) for bioMérieux IgM to 91.2% (87.0-94.2) for Siemens. The lowest negative percent agreement (NPA) was found with the Wantai Total Ab assay (NPA 33% (21.1-48.3)). The NPA for other total Ab or IgG assays targeting the S or the RBD was 80.7% (66.7-89.7), 90.3 (78.1-96.1) and 96.8% (86.8-99.3) for Siemens, bioMérieux IgG and DiaSorin, respectively. None of commercial assays have sufficient performance to detect a neutralizing titer of 80 (AUC<0.76).ConclusionsAlthough some assays presented a better agreement with VNT than others, the present findings emphasize that commercialized serological tests including those targeting the RBD cannot substitute a VNT for the assessment of functional antibody response.

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Suitability of Two Rapid Lateral Flow Immunochromatographic Assays for Predicting SARS-CoV-2 Neutralizing Activity of Sera

10.1101/2020.09.23.20198713 ◽

2020 ◽

Author(s):

Arantxa Valdivia ◽

Ignacio Torres ◽

Victor Latorre ◽

Clara Frances-Gomez ◽

Josep Ferrer ◽

...

Keyword(s):

Predictive Value ◽

Fluorescent Protein ◽

Neutralizing Antibody ◽

Antibody Test ◽

Neutralization Assay ◽

Positive Control ◽

Lateral Flow ◽

Control Line ◽

Assay Sensitivity ◽

Neutralizing Activity

Purpose: Assessment of commercial SARS-CoV-2 immunoassays for their capacity to provide reliable information on sera neutralizing activity is an emerging need. We evaluated the performance of two commercially-available lateral flow immunochromatographic assays (LFIC) (Wondfo SARS-CoV-2 Antibody test and the INNOVITA 2019-nCoV Ab test) in comparison with a SARS-CoV-2 neutralization pseudotyped assay for COVID-19 diagnosis in hospitalized patients, and investigate whether the intensity of the test band in LFIC associates with neutralizing antibody (NtAb) titers. Patients and Methods: Ninety sera were included from 51 patients with moderate to severe COVID-19. A green fluorescent protein (GFP) reporter-based pseudotyped neutralization assay (vesicular stomatitis virus coated with SARS-CoV-2 spike protein) was used. Test line intensity was scored using a 4-level scale (0 to 3+). Results: Overall sensitivity of LFIC assays was 91.1% for the Wondfo SARS-CoV-2 Antibody test, 72.2% for the INNOVITA 2019-nCoV IgG, 85.6% for the INNOVITA 2019-nCoV IgM and 92.2% for the NtAb assay. Sensitivity increased for all assays in sera collected beyond day 14 after symptoms onset (93.9%, 79.6%,93.9% and 93.9%, respectively). Reactivities equal to or more intense than the positive control line (≥2+) in the Wondfo assay had a negative predictive value of 100% and a positive predictive value of 96.4% for high NtAb50 titers (≥1/160). Conclusions: Our findings support the use of LFIC assays evaluated herein, particularly the Wondfo test, for COVID-19 diagnosis. We also find evidence that these rapid immunoassays can be used to predict high SARS-CoV-2-S NtAb50 titers.

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IMMUNOLOGICAL REACTIONS OF THE COXSACKIE VIRUSES

Journal of Experimental Medicine ◽

10.1084/jem.92.5.463 ◽

1950 ◽

Vol 92 (5) ◽

pp. 463-482 ◽

Cited By ~ 29

Author(s):

Joseph L. Melnick ◽

Nada Ledinko

Keyword(s):

North Carolina ◽

Neutralizing Antibodies ◽

Neutralization Test ◽

Normal Population ◽

Standard Procedure ◽

Neutralizing Antibody ◽

The United States ◽

Immune Serum ◽

Newborn Mice ◽

Immunological Reactions

The neutralization test is a reliable and useful procedure for following immunological reactions of the Coxsackie viruses (C virus). The standard procedure has been an incubation period of 1 hour at room temperature followed by subcutaneous inoculation into newborn mice. However, this time and temperature are not critical, for the virus in neutralized within 10 minutes of mixing with immune serum and remains neutralized for long periods. During the variable incubation periods used, the control virus remained active, even in dilute suspensions. The neutralization test is not affected by the presence or absence of complement. Neutralizing antibody is stable at 65°C. for 30 minutes, and immune serum has to be heated to 80°C. for 30 minutes before the antibody is no longer detectable. As the quantity of virus is increased, the quantity of serum required for neutralization likewise increases, but not in a regular or predictable fashion. Neutralized mixtures of the virus can be made infective again by simple dilution before inoculation. The neutralization test is a satisfactory means for typing Coxsackie viruses. At least seven antigenic types have been identified. Similar antigenic types have been found to be scattered over wide areas. Thus the Conn.-5 type was present in 1948 in Massachusetts, Connecticut, New York, and North Carolina. The Texas-1 type was present in 1943 in Connecticut and in 1948 in North Carolina and Texas. Further information on the specificity of the neutralizing antibody response has been obtained from a study of the occurrence and development of antibodies in 6 patients who contracted infections with one or another of the C viruses while working with them in the laboratory. From each patient a virus was isolated during the illness. No patient had detectable antibodies to his strain before his illness, but each soon thereafter developed antibodies to his own strain and to the prototype strain to which it was related. By means of the neutralization test, it has been shown that a family epidemic may include two different immunological types of virus. Neutralizing antibodies appear at the time of or soon after onset of illness, increase rapidly to titers of about 1:1000 which are maintained during the period of 1 to 3 months following infection, and are still present 2 years later, although at lower levels. Neutralizing antibodies are present in the normal population. In North Carolina, over 80 per cent of the children have antibodies at birth. The level falls rapidly to a minimum of 14 per cent at the age of 1, and then it quickly rises to reach the adult level at the age of 7. Gamma globulin collected in various parts of the United States between 1944 and 1949 and in Denmark in 1949 neutralizes at least four antigenically different Coxsackie viruses.

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A novel approach for evaluating antibodies against SARS-CoV-2 using menstrual blood collected from sanitary napkins before and after vaccination and evaluation of the visual napkin score

10.21203/rs.3.rs-737828/v2 ◽

2021 ◽

Author(s):

Hiromitsu Shirasawa ◽

Yukiyo Kumazawa ◽

Shiori Kushima ◽

Ayaka Fujishima ◽

Wataru Sato ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Conflicts Of Interest ◽

Antibody Test ◽

Positive Control ◽

University Hospital ◽

Menstrual Blood ◽

Blood Collection ◽

Control Line ◽

Sample Type ◽

Antibody Testing

Abstract BackgroundAlthough saliva, whole blood, serum, plasma, urine, and feces have been used as specimens for SARS-CoV-2 antigen and antibody tests, menstrual blood has not been reported to date. Unlike invasive blood collection methods, menstrual blood collected non-invasively from participants can be used to evaluate the presence of antibodies against SARS-CoV-2. The purpose of our report is to show an association between menstrual blood and the presence of neutralizing antibodies acquired via mRNA vaccination and the usefulness of menstrual blood as a sample type for detecting SARS-CoV-2 antibodies, considering the volume of blood in sanitary napkins as visual napkin score (VNS).MethodsIn this study, we collected one napkin each from 40 participants visiting the outpatient gynecology clinic of our university hospital with no symptoms related to COVID-19 and attempted to collect their menstrual blood from the napkins. In 5 of 40 participants, menstrual blood was collected after at least one dose of mRNA vaccination. For this study, the maximum volume of menstrual blood collected was set as 980 μl. In addition, the classification of napkins based on the VNS was set, with level 1 being the lowest percentage of blood on the napkin (0–20%) and level 5 being the highest category (80–100%), according to the consensus of two researchers. We have evaluated used four different antibody testing kits using menstrual blood for detecting IgG and IgM.FindingsThe mean amount of menstrual blood collected from the 40 participants' sanitary napkins was 364 ± 372 μl; higher VNS indicated more menstrual blood collected. Statistically, VNS 3 or higher resulted in significantly higher menstrual blood collection than VNS 1 (p<0.01). With VNS 1, the collection of menstrual blood was complicated, and antibody test kits could not be tested for all eight participants. On the other hand, 31 of 32 participants (96.9%) with VNS 2 or higher could be tested with one or more antibody test kits. For all testing kits, 100% of tests with menstrual blood had a positive control line, and all participants who tested positive for IgG and IgM had received a COVID-19 mRNA vaccine. In the five participants after mRNA vaccination, only two of the four testing kits were all positive for IgG.InterpretationWe have, for the first time, evaluated antibodies against SARS-CoV-2 in menstrual blood collected from sanitary napkins with several antibody test kits. We found that if more than 20% of the napkin area has menstrual blood on it, sufficient menstrual blood can be collected for antibody testing. We also confirmed that menstrual blood collected from a sanitary napkin could be used to detect antibody after mRNA COVID-19 vaccination. We believe that our results are a pioneering effort that has not been reported previously and will lead to better public health and development of wearable devices.FundingThere are no conflicts of interest to disclose for this study.

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Evaluation of Commercial Anti-SARS-CoV-2 Neutralizing Antibody Assays in seropositive subjects

10.1101/2022.01.04.22268652 ◽

2022 ◽

Author(s):

Kahina Saker ◽

Bruno Pozzetto ◽

Vanessa ESCURET ◽

Virginie Pitiot ◽

Amélie Massardier-Pilonchéry ◽

...

Keyword(s):

Functional Ability ◽

Neutralizing Antibodies ◽

Neutralization Test ◽

Neutralizing Antibody ◽

Added Value ◽

P Value ◽

Antibody Assays ◽

Qualitative Test ◽

User Friendly ◽

Commercial User

The virus neutralization test (VNT) is the reference for the assessment of the functional ability of neutralizing antibodies (NAb) to block SARS-CoV-2 entry into cells. New competitive immunoassays measuring antibodies preventing interaction between the spike protein and its cellular receptor are proposed as surrogate VNT (sVNT). We tested three commercial sVNT (a qualitative immunochromatographic test and two quantitative immunoassays named YHLO and TECO) together with a conventional anti-spike IgG assay (bioMerieux) in comparison with an in-house plaque reduction neutralization test (PRNT50) using the original 19A strain and different variants of concern (VOC), on a panel of 306 sera from naturally-infected or vaccinated patients. The qualitative test was rapidly discarded because of poor sensitivity and specificity. Areas under the curve of YHLO and TECO assays were, respectively, 85.83 and 84.07 (p-value >0.05) using a positivity threshold of 20 for PRNT50, and 95.63 and 90.35 (p-value =0.02) using a threshold of 80. However, the performances of YHLO and bioMerieux were very close for both thresholds, demonstrating the absence of added value of sVNT compared to a conventional assay for the evaluation of the presence of NAb in seropositive subjects. In addition, the PRNT50 assay showed a reduction of NAb titers towards different VOC in comparison to the 19A strain that could not be appreciated by the commercial tests. Despite the good correlation between the anti-spike antibody titer and the titer of NAb by PRNT50, our results highlight the difficulty to distinguish true NAb among the anti-RBD antibodies with commercial user-friendly immunoassays.

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Predicting COVID-19 Vaccine Efficacy from Neutralizing Antibody Levels

10.1101/2021.10.13.21264921 ◽

2021 ◽

Author(s):

Majid R. Abedi ◽

Samuel Dixon ◽

Timothy Guyon ◽

Serene Hsu ◽

Aviva R. Jacobs ◽

...

Keyword(s):

High Throughput ◽

Vaccine Efficacy ◽

Neutralizing Antibodies ◽

Neutralization Test ◽

Neutralizing Antibody ◽

Published Data ◽

Real World Data ◽

Symptomatic Infection ◽

Viral Neutralization ◽

Antibody Levels

Recent studies using data accrued from global SARS-CoV-2 vaccination efforts have demonstrated that breakthrough infections are correlated with levels of neutralizing antibodies. The decrease in neutralizing antibody titers of vaccinated individuals over time, combined with the emergence of more infectious variants of concern has resulted in waning vaccine efficacy against infection and a rise in breakthrough infections. Here we use a combination of neutralizing antibody measurements determined by a high throughput surrogate viral neutralization test (sVNT) together with published data from vaccine clinical trials and comparative plaque reduction neutralization test (PRNT) between SARS-CoV-2 variants to develop a model for vaccine efficacy (VE) against symptomatic infection. Vaccine efficacy estimates using this model show good concordance with real world data from the US and Israel. Our work demonstrates that appropriately calibrated neutralizing antibody measurements determined by high throughput sVNT can be used to provide a semi-quantitative estimate of protection against infection. Given the highly variable antibody levels among the vaccinated population, this model may be of use in identification of individuals with an elevated risk of breakthrough infections.

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West Nile virus neutralizing antibody prevalence in donkeys from northern Nigeria

Transactions of the Royal Society of Tropical Medicine and Hygiene ◽

10.1093/trstmh/traa104 ◽

2020 ◽

Author(s):

Idoko Sunday Idoko ◽

Gili Schvartz ◽

Sharon Tirosh-Levy ◽

Oran Erster ◽

Jibril Yakubu Jibril ◽

...

Keyword(s):

West Nile Virus ◽

Neutralizing Antibodies ◽

Healthy Adult ◽

Neutralization Test ◽

Neutralizing Antibody ◽

Virus Neutralization Test ◽

Northern Nigeria ◽

Antibody Prevalence ◽

West Nile ◽

Zoonotic Pathogen

Abstract Background This study aimed to evaluate the prevalence of anti-West Nile virus (WNV) neutralizing antibodies in donkeys from two areas in northern Nigeria. Methods Serology was determined by a virus neutralization test in samples collected from 205 healthy adult donkeys. Results Fifty-seven donkeys (27.8%) tested seropositive for WNV. Donkeys from Zaria were 2.6 times more likely to have been exposed to WNV (p<0.001). Conclusion The results of this study demonstrate that this zoonotic pathogen is prevalent in these areas and that measures should be implemented to reduce the risk for both humans and equids.

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