scholarly journals A highly sensitive and specific SARS-CoV-2 spike- and nucleoprotein-based fluorescent multiplex immunoassay (FMIA) to measure IgG, IgA and IgM class antibodies

2021 ◽  
Author(s):  
Anna Solastie ◽  
Camilla Virta ◽  
Anu Haveri ◽  
Nina Ekström ◽  
Anu Kantele ◽  
...  
Keyword(s):  
Strong Correlation ◽  
Time Window ◽  
Clinical Performance ◽  
World Health Organisation ◽  
World Health ◽  
Spike Glycoprotein ◽  
Neutralising Antibodies ◽  
Multiplex Immunoassay ◽  
International Standard ◽  
Specificity And Sensitivity

Background. Validation and standardization of accurate serological assays are crucial for the surveillance of the coronavirus disease 2019 (COVID-19) pandemic and population immunity. Methods. We describe the analytical and clinical performance of an in-house fluorescent multiplex immunoassay (FMIA) for simultaneous quantification of antibodies against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleoprotein and spike glycoprotein. Furthermore, we calibrated IgG-FMIA against World Health Organisation (WHO) International Standard and compared FMIA results to an in-house enzyme immunoassay (EIA) and a microneutralisation test (MNT). We also compared the MNT results of two laboratories. Results. IgG-FMIA displayed 100% specificity and sensitivity for samples collected 13-150 days post-onset of symptoms (DPO). For IgA- and IgM-FMIA 100% specificity and sensitivity were obtained for a shorter time window (13-36 and 13-28 DPO for IgA- and IgM-FMIA, respectively). FMIA and EIA results displayed moderate to strong correlation, but FMIA was overall more specific and sensitive. IgG-FMIA identified 100% of samples with neutralising antibodies (NAbs). Anti-spike IgG concentrations correlated strongly (ρ=0.77-0.84, P<2.2x10-16) with NAb titers. The NAb titers of the two laboratories displayed a very strong correlation (ρ=0.95, P<2.2x10-16). Discussion. Our results indicate good correlation and concordance of antibody concentrations measured with different types of in-house SARS-CoV-2 antibody assays. Calibration against WHO international standard did not, however, improve the comparability of FMIA and EIA results. keywords: SARS-CoV-2, COVID-19, antibody, immunoassay, nucleoprotein, spike glycoprotein, WHO international standard, neutralising antibodies, microneutralisation, receptor-binding domain

A Collaborative Study to Establish the Second International Standard for Streptokinase

1990 ◽  
Vol 64 (02) ◽  
pp. 267-269 ◽  
Author(s):  
A B Heath ◽  
P J Gaffney
Keyword(s):  
High Purity ◽  
Collaborative Study ◽  
World Health Organisation ◽  
World Health ◽  
Clot Lysis ◽  
Current Standard ◽  
International Standard ◽  
Accelerated Degradation ◽  
The World ◽  
International Collaborative Study

SummaryAn International Standard for Streptokinase - Streptodomase (62/7) has been used to calibrate high purity clinical batches of SK since 1965. An international collaborative study, involving six laboratories, was undertaken to replace this standard with a high purity standard for SK. Two candidate preparations (88/826 and 88/824) were compared by a clot lysis assay with the current standard (62/7). Potencies of 671 i.u. and 461 i.u. were established for preparations A (88/826) and B (88/824), respectively.Either preparation appeared suitable to serve as a standard for SK. However, each ampoule of preparation A (88/826) contains a more appropriate amount of SK activity for potency testing, and is therefore preferred. Accelerated degradation tests indicate that preparation A (88/826) is very stable.The high purity streptokinase preparation, coded 88/826, has been established by the World Health Organisation as the 2nd International Standard for Streptokinase, with an assigned potency of 700 i.u. per ampoule.

A Collaborative Study to Establish an International Standard for Alpha-Thrombin

1992 ◽  
Vol 67 (04) ◽  
pp. 424-427 ◽  
Author(s):  
P J Gaffney ◽  
A B Heath ◽  
J W Fenton II
Keyword(s):  
Elevated Temperatures ◽  
Collaborative Study ◽  
World Health Organisation ◽  
Significant Loss ◽  
Thrombin Inhibitors ◽  
World Health ◽  
Expert Committee ◽  
International Standard ◽  
Assay Procedure ◽  
And Control

SummarySince 1975 an International Standard for Thrombin of low purity has been used. While this standard was stable and of value for calibrating thrombins of unknown potency the need for a pure a-thrombin standard arose both for accurate calibration and for precise measurement of thrombin inhibitors, notably hirudin. An international collaborative study was undertaken to establish the potency and stability of an ampouled pure a-thrombin preparation. A potency of 97.5 international units (95% confidence limits 86.5-98.5) was established for the new a-thrombin standard (89/ 588) using a clotting-assay procedure. Stability data at various elevated temperatures indicated that the standard could be transported and stored with no significant loss of potency.Ampoules of lyophilised a-thrombin (coded 89/588) have been recommended as an International Standard for a-thrombin with an assigned potency of 100 international units per ampoule by the International Society for Thrombosis and Haemostasis (Thrombin and its Inhibitors Sub-Committee) in Barcelona, Spain in July 1990 while the Expert Committee on Biological Standardisation and Control of the World Health Organisation will consider its status at its next meeting in Geneva in 1991.

scholarly journals Standardised, quantitative neutralisation responses to SARS-CoV-2 Variants of Concern by convalescent anti-sera from first wave infections of UK Health Care Workers and Patients

2021 ◽  
Author(s):  
Diego Cantoni ◽  
Martin Mayora-Neto ◽  
Angalee Nadesalingam ◽  
David A. Wells ◽  
George W. Carnell ◽  
...  
Keyword(s):  
Health Care Workers ◽  
Healthcare Workers ◽  
World Health Organisation ◽  
World Health ◽  
Care Centre ◽  
International Standard ◽  
Care Workers ◽  
The World ◽  
Antibody Titres ◽  
The Uk

One of the defining criteria of Variants of Concern (VOC) is their ability to evade pre-existing immunity, increased transmissibility, morbidity and/or mortality. Here we examine the capacity of convalescent plasma, from a well defined cohort of healthcare workers (HCW) and Patients infected during the first wave from a national critical care centre in the UK, to neutralise B.1.1.298 variant and three VOCs; B.1.1.7, B.1.351 and P.1. Furthermore, to enable lab to lab, country to country comparisons we utilised the World Health Organisation (WHO) International Standard for anti-SARS-CoV-2 Immunoglobulin to report neutralisation findings in International Units. These findings demonstrate a significant reduction in the ability of first wave convalescent plasma to neutralise the VOCs. In addition, Patients and HCWs with more severe COVID-19 were found to have higher antibody titres and to neutralise the VOCs more effectively than individuals with milder symptoms. Widespread use of the WHO International Standard by laboratories in different countries will allow for cross-laboratory comparisons, to benchmark and to establish thresholds of protection against SARS-CoV-2 and levels of immunity in different settings and countries.

scholarly journals assayM: a web application to monitor mutations in COVID-19 diagnostic assays

2020 ◽  
Author(s):  
Raeece Naeem ◽  
Arnab Pain
Keyword(s):  
Web Application ◽  
Pcr Primers ◽  
World Health Organisation ◽  
Virus Genome ◽  
World Health ◽  
Rt Pcr ◽  
Diagnostic Assays ◽  
Link Type ◽  
Specificity And Sensitivity ◽  
R Shiny

AbstractSummaryReverse Transcriptase – Polymerase Chain Reaction (RT-PCR) is the gold standard as diagnostic assays for the detection of COVID-19 and the specificity and sensitivity of these assays depend on the complementarity of the RT-PCR primers to the genome of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Since the virus mutates over time during replication cycles, there is an urgent need to continuously monitor the virus genome for appearances of mutations and mismatches in the PCR primers used in these assays. Here we present assayM, a web application to explore and monitor mutations introduced in the primer and probe sequences published by the World Health Organisation (WHO) or in any custom-designed assay primers for SARS-CoV-2 detection assays in globally available SARS-CoV-2 genome datasets.Availability and implementationassayM is available on https://grafnet.kaust.edu.sa/assayM as a web application and also as an open-source R shiny application, downloadable from https://github.com/raeece/[email protected]

A Collaborative Study to Establish the 6th International Standard for Factor VIII Concentrate

2001 ◽  
Vol 85 (06) ◽  
pp. 1071-1078 ◽  
Author(s):  
A. B. Heath ◽  
T. W. Barrowcliffe ◽  
S. Raut
Keyword(s):  
Factor Viii ◽  
Collaborative Study ◽  
World Health Organisation ◽  
World Health ◽  
Assay Method ◽  
Expert Committee ◽  
International Standard ◽  
One Stage ◽  
The One ◽  
Good Agreement

SummaryA study was carried out to replace the 5th WHO International Standard (IS) for factor VIII concentrate, because of depletion of stocks. Two candidate concentrates (X and Y) were assayed as potential replacements against the 5th IS for FVIII concentrate, in a collaborative study involving 33 laboratories. Collaborators were asked to use the ISTH/SSC recommendations, including pre-dilution of concentrates in FVIII deficient plasma in their assays. Several laboratories performed more than one assay method and altogether there were 21 sets of assays with the one-stage method, 6 with the two-stage method and 26 with the chromogenic method. There was good agreement between laboratories using each method for the comparison of concentrates X and Y against the 5th IS, but the overall potencies by one-stage and chromogenic methods each differed by approximately 5% from the overall mean, with the chromogenic potency approximately 10% higher than the one-stage. Inter-laboratory agreement was slightly better for concentrate Y than X, and stability studies indicated that Y was more stable than X. After considering all the information, together with comments from participants and from the FVIII/FIX Subcommittee of the ISTH/SSC, candidate Y (NIBSC code [97/616]), was proposed and accepted in October, 1998, by the Expert Committee on Biological Standardisation of the World Health Organisation to be the 6th International Standard for Factor VIII Concentrate with an assigned potency of 8.5 IU/ampoule.

scholarly journals Analysis of Serological Biomarkers of SARS-CoV-2 Infection in Convalescent Samples From Severe, Moderate and Mild COVID-19 Cases

2021 ◽  
Vol 12 ◽  
Author(s):  
Javier Castillo-Olivares ◽  
David A. Wells ◽  
Matteo Ferrari ◽  
Andrew C. Y. Chan ◽  
Peter Smith ◽  
...  
Keyword(s):  
Large Scale ◽  
World Health Organisation ◽  
Epidemiological Studies ◽  
Antibody Responses ◽  
Clinical Severity ◽  
World Health ◽  
Binding Assays ◽  
Neutralising Antibodies ◽  
Antibody Assays ◽  
Binding Antibody

Precision monitoring of antibody responses during the COVID-19 pandemic is increasingly important during large scale vaccine rollout and rise in prevalence of Severe Acute Respiratory Syndrome-related Coronavirus-2 (SARS-CoV-2) variants of concern (VOC). Equally important is defining Correlates of Protection (CoP) for SARS-CoV-2 infection and COVID-19 disease. Data from epidemiological studies and vaccine trials identified virus neutralising antibodies (Nab) and SARS-CoV-2 antigen-specific (notably RBD and S) binding antibodies as candidate CoP. In this study, we used the World Health Organisation (WHO) international standard to benchmark neutralising antibody responses and a large panel of binding antibody assays to compare convalescent sera obtained from: a) COVID-19 patients; b) SARS-CoV-2 seropositive healthcare workers (HCW) and c) seronegative HCW. The ultimate aim of this study is to identify biomarkers of humoral immunity that could be used to differentiate severe from mild or asymptomatic SARS-CoV-2 infections. Some of these biomarkers could be used to define CoP in further serological studies using samples from vaccination breakthrough and/or re-infection cases. Whenever suitable, the antibody levels of the samples studied were expressed in International Units (IU) for virus neutralisation assays or in Binding Antibody Units (BAU) for ELISA tests. In this work we used commercial and non-commercial antibody binding assays; a lateral flow test for detection of SARS-CoV-2-specific IgG/IgM; a high throughput multiplexed particle flow cytometry assay for SARS-CoV-2 Spike (S), Nucleocapsid (N) and Receptor Binding Domain (RBD) proteins); a multiplex antigen semi-automated immuno-blotting assay measuring IgM, IgA and IgG; a pseudotyped microneutralisation test (pMN) and an electroporation-dependent neutralisation assay (EDNA). Our results indicate that overall, severe COVID-19 patients showed statistically significantly higher levels of SARS-CoV-2-specific neutralising antibodies (average 1029 IU/ml) than those observed in seropositive HCW with mild or asymptomatic infections (379 IU/ml) and that clinical severity scoring, based on WHO guidelines was tightly correlated with neutralisation and RBD/S antibodies. In addition, there was a positive correlation between severity, N-antibody assays and intracellular virus neutralisation.

scholarly journals Comparative Analysis Based on the Spike Glycoproteins of SARS-CoV2 Isolated from COVID 19 Patients of Different Countries

2020 ◽  
Author(s):  
Preeti Mangar ◽  
Smriti Pradhan ◽  
Subecha Rai ◽  
Khusboo Lepcha ◽  
Vivek Kumar Ranjan ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Point Mutations ◽  
World Health Organisation ◽  
World Health ◽  
Structural Proteins ◽  
Spike Glycoprotein ◽  
The World ◽  
Transmittance Factor ◽  
Over Time

SARS-CoV2 popularly known as (COVID-19) has presently received worldwide attention. It has been considered a pandemic by the World Health Organisation. Owing to its high transmittance factor the virus has brought about many deaths and spread to all the major countries of the world. Scientists and Researchers worldwide are giving their full efforts to develop a vaccine. In our present study, we have included the comparative analysis of the different spike glycoprotein sequences of the patients suffering from COVID-19 from different countries where this pandemic has occurred. Spike glycoproteins are the structural proteins that bring about the binding of the SARS-CoV-2 viral molecule to the ACE2 receptor of the host following which infection occurs. Through this data, we have shown the different point mutations in the spike glycoproteins that occurred over time in different countries as the disease progressed.

A Collaborative Study to Establish the 5th International Standard for Unfractionated Heparin

2000 ◽  
Vol 84 (12) ◽  
pp. 1017-1022 ◽  
Author(s):  
A. Walker ◽  
Barbara Mulloy ◽  
Trevor Barrowcliffe ◽  
Elaine Gray
Keyword(s):  
Molecular Weight ◽  
Unfractionated Heparin ◽  
Specific Activity ◽  
Collaborative Study ◽  
World Health Organisation ◽  
The Other ◽  
World Health ◽  
Expert Committee ◽  
International Standard ◽  
The World

SummaryTwenty-four laboratories participated in a collaborative study to calibrate a replacement for the 4th International Standard for Unfractionated Heparin (82/502). Both candidate materials A and B, gave excellent intra- and inter-laboratory variations (majority of mean %gcv <10%) when assayed against the 4th International Standard. No major differences of potency estimates were found between methods, although the USP method generally gave lower potencies than the other methods and candidate B gave a greater variation between methods than A. Overall, this study showed that the differences between the candidates are marginal. Based on its narrower molecular weight profile, higher specific activity and slightly lower inter-method variation, candidate A, 97/578, was proposed and accepted in October, 1998, by the Expert Committee on Biological Standardisation of the World Health Organisation to be the 5th International Standard for Unfractionated Heparin with an assigned potency of 2031 IU/ampoule.

Collaborative Study of a Proposed International Standard for Plasma Fibrinogen Measurement

1992 ◽  
Vol 68 (04) ◽  
pp. 428-432 ◽  
Author(s):  
Patrick J Gaffney ◽  
M Y Wong
Keyword(s):  
Collaborative Study ◽  
World Health Organisation ◽  
Plasma Fibrinogen ◽  
World Health ◽  
Expert Committee ◽  
International Standard ◽  
Assay Procedure ◽  
Artery Disease ◽  
And Control ◽  
The Relationship

SummaryThere is increased interest in the relationship between plasma fibrinogen levels and the incidence of coronary artery disease. The National Institute for Biological Standards and Control (UK) has completed a study to establish an International Standard for plasma fibrinogen. This study was conducted using a recommended assay procedure to measure the clottable material present in the proposed lyophilised Standard (coded 89/644). Twenty-two laboratories from nine countries took part in the study and analysis of the data allowed the calibration of 89/644 at 2.4 mg/ml clottable protein. Agreement with this figure was established in two laboratories using three or more different assays for plasma fibrinogen. Degradation studies of the proposed plasma fibrinogen Standard suggested that no loss of clottable protein was observed when the lyophilised material was stored at 20° C for 1 year.The Fibrinogen Sub-Committee of the ISTH (Amsterdam, The Netherlands, June 1991) supported the establishment of 89/644 as an International Standard. This collaborative study will be presented to the Expert Committee on Biological Standardisation of the World Health Organisation at their 1992 session. In the meantime 89/644 will be distributed as the proposed International Standard for plasma fibrinogen measurement containing 2.4 mg/ ml clottable protein.

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