SARS Coronavirus-2 Microneutralisation and Commercial Serological Assays Correlated Closely for Some but Not All Enzyme Immunoassays

Serological testing for SARS-CoV-2-specific antibodies provides important research and diagnostic information relating to COVID-19 prevalence, incidence and host immune response. A greater understanding of the relationship between functionally neutralising antibodies detected using microneutralisation assays and binding antibodies detected using scalable enzyme immunoassays (EIA) is needed in order to address protective immunity post-infection or vaccination, and assess EIA suitability as a surrogate test for screening of convalescent plasma donors. We assessed whether neutralising antibody titres correlated with signal cut-off ratios in five commercially available EIAs, and one in-house assay based on expressed spike protein targets. Sera from recovered patients or convalescent plasma donors who reported laboratory-confirmed SARS-CoV-2 infection (n = 200), and negative control sera collected prior to the COVID-19 pandemic (n = 100), were assessed in parallel. Performance was assessed by calculating EIA sensitivity and specificity with reference to microneutralisation. Neutralising antibodies were detected in 166 (83%) samples. Compared with this, the most sensitive EIAs were the Cobas Elecsys Anti-SARS-CoV-2 (98%) and Vitros Immunodiagnostic Anti-SARS-CoV-2 (100%), which detect total antibody targeting the N and S1 antigens, respectively. The assay with the best quantitative relationship with microneutralisation was the Euroimmun IgG. These results suggest the marker used (total Ab vs. IgG vs. IgA) and the target antigen are important determinants of assay performance. The strong correlation between microneutralisation and some commercially available assays demonstrates their potential for clinical and research use in assessing protection following infection or vaccination, and use as a surrogate test to assess donor suitability for convalescent plasma donation.

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SARS Coronavirus-2 microneutralisation and commercial serological assays correlated closely for some but not all enzyme immunoassays

10.1101/2020.12.07.20245696 ◽

2020 ◽

Author(s):

Gregory J Walker ◽

Zin Naing ◽

Alberto Ospina Stella ◽

Malinna Yeang ◽

Joanna Caguicla ◽

...

Keyword(s):

Quantitative Relationship ◽

Negative Control ◽

Target Antigen ◽

Neutralising Antibodies ◽

Protein Targets ◽

Enzyme Immunoassays ◽

Parallel Performance ◽

Assay Performance ◽

Antibody Titres ◽

The Relationship

AbstractBackgroundSerological testing for SARS-CoV-2 specific antibodies provides important research and diagnostic information relating to COVID-19 prevalence, incidence, and host immune response. A greater understanding of the relationship between functionally neutralising antibodies detected using microneutralisation assays and binding antibodies detected using scalable enzyme immunoassays (EIA) is needed in order to address protective immunity post-infection or vaccination, and assess EIA suitability as a surrogate test for screening of convalescent plasma donors. We assessed whether neutralising antibody titres correlated with signal cut-off ratios in five commercially available EIAs, and one in-house assay based on expressed spike protein targets.MethodsSera from individuals recovered from patients or convalescent plasma donors who reported laboratory-confirmed SARS-CoV-2 infection (n=200), and negative control sera collected prior to the COVID-19 pandemic (n=100) were assessed in parallel. Performance was assessed by calculating EIA sensitivity and specificity with reference to microneutralisation.ResultsNeutralising antibodies were detected in 166 (83%) samples. Compared with this, the most sensitive EIAs were the Cobas Elecsys Anti-SARS-CoV-2 (98%) and Vitros Immunodiagnostic Anti-SARS-CoV-2 (100%), which detect total antibody targeting the N and S1 antigens, respectively. The assay with the best quantitative relationship with microneutralisation was the Euroimmun IgG.ConclusionsThese results suggest the marker used (total Ab vs IgG vs IgA), and the target antigen are important determinants of assay performance. The strong correlation between microneutralisation and some commercially available assays demonstrate their potential for clinical and research use in assessing protection following infection or vaccination, and use as a surrogate test to assess donor suitability for convalescent plasma donation.

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Is duodenal biopsy always necessary for the diagnosis of coeliac disease in adult patients with high anti-tissue transglutaminase (TTG) antibody titres?

Frontline Gastroenterology ◽

10.1136/flgastro-2020-101728 ◽

2021 ◽

pp. flgastro-2020-101728

Author(s):

Junaid Beig ◽

Kamran Rostami ◽

David T S Hayman ◽

Summer Hassan ◽

Stephen Gerred ◽

...

Keyword(s):

Coeliac Disease ◽

Linear Models ◽

Tissue Transglutaminase ◽

Signs And Symptoms ◽

Duodenal Biopsy ◽

Adult Patients ◽

Antibody Titres ◽

Red Flag ◽

The Relationship ◽

Duodenal Biopsies

ObjectiveAvoiding duodenal biopsy in adults for coeliac disease (CD) diagnosis is controversial. Some retrospective and prospective studies have shown that CD can be reliably diagnosed in adults with serology rather than duodenal biopsies. This study aimed to check the accuracy of a cut-off value of ≥10 upper limit of normal of anti-tissue transglutaminase antibody (anti-TTG IgA) titres for CD diagnosis in adult patients.MethodWe retrospectively analysed adult patients (≥16 years) who underwent gastroscopy from 2013 to 2018 for positive coeliac serology. The relationship between titres and disease was determined by using linear models, whereas sensitivity and specificity were assessed by receiver operator curve.ResultsWe analysed 144 newly anti-TTG antibody-positive adult patients with a median age of 48.5 years (IQR 32–62); among them, 86 (60%) patients had CD (Marsh III: n=68 and Marsh II and I: n=18) with a higher prevalence in females (n=59 (69%)) and Europeans (n=60 (70%)). Fifty (58%) patients with CD had colonoscopy and five (6%) had imaging; only six patients were diagnosed with additional conditions. An anti-TTG IgA titre cut-off value of 150 U/L was 100% specific for CD in our dataset, with 70% (95% CI: 60% to 88%) sensitivity for this patient group.ConclusionCoeliac serology using anti-TTG IgA with titres ≥10× normal value is an excellent predictor of CD, irrespective of age, gender and ethnicity. Duodenal biopsy may not be necessary in selected adult patients with CD, especially younger than 50 years of age without additional gastrointestinal red-flag signs and symptoms.

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RESOURCE UTILIZATION BY THE SOUTHERN PINE BEETLE, DENDROCTONUS FRONTALIS (COLEOPTERA: SCOLYTIDAE)

The Canadian Entomologist ◽

10.4039/ent108353-4 ◽

1976 ◽

Vol 108 (4) ◽

pp. 353-362 ◽

Cited By ~ 40

Author(s):

Robert N. Coulson ◽

Adil M. Mayyasi ◽

J. L. Foltz ◽

F. P. Hain ◽

W. C. Martin

Keyword(s):

Pinus Taeda ◽

Resource Utilization ◽

Loblolly Pine ◽

Quantitative Relationship ◽

Dendroctonus Frontalis ◽

Adult Density ◽

Pine Beetle ◽

Basal Portion ◽

Relationship Of ◽

The Relationship

AbstractThe process of resource utilization by Dendroctonus frontalis Zimmerman attacking loblolly pine, Pinus taeda L., was investigated. The quantitative relationship of attacking parent adult D. frontalis as a function of the normalized infested bole height is described by the model y = Ax(1−x)eBx. Greatest attack density occurs at the mid-bole of the tree and tapers toward the top and bottom. Gallery length (and hence eggs)/100 cm2 was independent of attack density. The relationship between gallery length (or eggs) per parent adult and parent adult density is described by the exponential decay curve y = AeBx, indicating that gallery length and egg population density are controlled by a density dependent compensatory feedback process operating instantaneously. Further support for the mechanism was obtained by analyzing the gallery length per parent adult at different locations on the infested bole. The relationship is described by the model y = [AeBx]/[x(1−x)] and indicates that gallery construction and egg population per attacking beetle increase in the upper and basal portion of the bole. The result is a uniform amount of food and space per individual of the developing population.

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Collaborative networks enable the rapid establishment of serological assays for SARS-CoV-2 during nationwide lockdown in New Zealand

PeerJ ◽

10.7717/peerj.9863 ◽

2020 ◽

Vol 8 ◽

pp. e9863 ◽

Cited By ~ 2

Author(s):

Reuben McGregor ◽

Alana L. Whitcombe ◽

Campbell R. Sheen ◽

James M. Dickson ◽

Catherine L. Day ◽

...

Keyword(s):

New Zealand ◽

Respiratory Infections ◽

Serum Antibody ◽

Clinical Diagnostics ◽

Neutralising Antibodies ◽

Past Infection ◽

Travel History ◽

The Relationship ◽

Collaborative Efforts ◽

Prior Infection

Background Serological assays that detect antibodies to SARS-CoV-2 are critical for determining past infection and investigating immune responses in the COVID-19 pandemic. We established ELISA-based immunoassays using locally produced antigens when New Zealand went into a nationwide lockdown and the supply chain of diagnostic reagents was a widely held domestic concern. The relationship between serum antibody binding measured by ELISA and neutralising capacity was investigated using a surrogate viral neutralisation test (sVNT). Methods A pre-pandemic sera panel (n = 113), including respiratory infections with symptom overlap with COVID-19, was used to establish assay specificity. Sera from PCR‑confirmed SARS-CoV-2 patients (n = 21), and PCR-negative patients with respiratory symptoms suggestive of COVID-19 (n = 82) that presented to the two largest hospitals in Auckland during the lockdown period were included. A two-step IgG ELISA based on the receptor binding domain (RBD) and spike protein was adapted to determine seropositivity, and neutralising antibodies that block the RBD/hACE‑2 interaction were quantified by sVNT. Results The calculated cut-off (>0.2) in the two-step ELISA maximised specificity by classifying all pre-pandemic samples as negative. Sera from all PCR-confirmed COVID-19 patients were classified as seropositive by ELISA ≥7 days after symptom onset. There was 100% concordance between the two-step ELISA and the sVNT with all 7+ day sera from PCR‑confirmed COVID-19 patients also classified as positive with respect to neutralising antibodies. Of the symptomatic PCR-negative cohort, one individual with notable travel history was classified as positive by two-step ELISA and sVNT, demonstrating the value of serology in detecting prior infection. Conclusions These serological assays were established and assessed at a time when human activity was severely restricted in New Zealand. This was achieved by generous sharing of reagents and technical expertise by the international scientific community, and highly collaborative efforts of scientists and clinicians across the country. The assays have immediate utility in supporting clinical diagnostics, understanding transmission in high-risk cohorts and underpinning longer‑term ‘exit’ strategies based on effective vaccines and therapeutics.

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Evaluation of tubal and peritoneal factors in chlamydia positive infertile women by laparoscope

Journal of Shaheed Suhrawardy Medical College ◽

10.3329/jssmc.v7i2.31442 ◽

2017 ◽

Vol 7 (2) ◽

pp. 54-58

Author(s):

Nurjahan Begum ◽

Fawzia Hussain ◽

Farzana Deeba ◽

Shaheen Ara Anwary ◽

Parveen Sultana ◽

...

Keyword(s):

Fallopian Tubes ◽

Test Results ◽

Immunofluorescence Test ◽

Common Cause ◽

Positive Group ◽

Chlamydia Trachomatis Infection ◽

Infertile Women ◽

Antibody Titres ◽

The Difference ◽

The Relationship

Background: Abnormalities or damage to the fallopian tube interferes with fertility and is responsible for abnormal implantation (eg, ectopic pregnancy). Obstruction of the distal end of the fallopian tubes results in accumulation of the normally secreted tubal fluid, creating distention of the tube with subsequent damage of the epithelial cilia (hydrosalpinx). Genital Chlamydia trachomatis infection has a worldwide distribution6 and is now recognized as the single most common cause of tubal peritoneal damage. The study explores the relationship between serum chlamydia antibody titres (CATs) and detection of tubal damage in infertile women.Objective: To Evaluation of tubal and peritonial factors in chlamydia positive infertile women by laparoscope.Methodology: The tubal status and pelvic findings in 138 women underwent laparoscopy for infertility were related to CAT, which was measured using the whole-cell inclusion immunofluorescence test. RESULTS: A total of 138 infertile women who underwent laparoscopic investigation for infertility were identified and they were divided in two groups, on the bsis of presence is absence Chlamydia positive (n=69) and Chlamydia Negative (n=69). Demographic status were almost similar between two groups, however service holder was found significantly higher in Chlamydia positive group (17 vs. 7). Tubal block was found in 44(63.7%) in Chlamydia positive and 37(53.6%) in Chlamydia negative. The difference was statistically significant (p<0.01) between two groups. Site of block & hydrosalpinges was almost similar between two groups. POD was completely obliterated in 10(14.5%) in Chlamydia positive and 3(4.3%) in Chlamydia negative. The difference was statistically significant (p<0.05) between two groups.Conclusion: Chlamydia serology is useful mainly as a screening test for the likelihood of tubal damage in infertile women and may facilitate decisions on which women should proceed with further investigations without delay.J Shaheed Suhrawardy Med Coll, December 2015, Vol.7(2); 54-58

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Relationships between snowfall density and solid hydrometeors, based on measured size and fall speed, for snowpack modeling applications

The Cryosphere ◽

10.5194/tc-10-2831-2016 ◽

2016 ◽

Vol 10 (6) ◽

pp. 2831-2845 ◽

Cited By ~ 7

Author(s):

Masaaki Ishizaka ◽

Hiroki Motoyoshi ◽

Satoru Yamaguchi ◽

Sento Nakai ◽

Toru Shiina ◽

...

Keyword(s):

Mass Flux ◽

Weather Forecasting ◽

Initial Density ◽

Quantitative Relationship ◽

Temperate Climate ◽

Snowfall Event ◽

Fall Speed ◽

Average Size ◽

Meteorological Elements ◽

The Relationship

Abstract. The initial density of deposited snow is mainly controlled by snowfall hydrometeors. The relationship between snowfall density and hydrometeors has been qualitatively examined by previous researchers; however, a quantitative relationship has not yet been established due to difficulty in parameterizing the hydrometeor characteristics of a snowfall event. Thus, in an earlier study, we developed a new variable, the centre of mass flux distribution (CMF), which we used to describe the main hydrometeors contributing to a snowfall event. The CMF is based on average size and fall speed weighted by the mass flux estimated from all measured hydrometeors in a snowfall event. It provides a quantitative representation of the predominant hydrometeor characteristics of the event. In this study, we examine the relationships between the density of newly fallen snow and predominant snow type as indicated by the CMFs. We measured snowfall density at Nagaoka, Japan, where riming and aggregation are predominant, simultaneously observing the size and fall speed of snowfall hydrometeors, and deduced the predominant hydrometeor characteristics of each snowfall event from their CMFs. Snow density measurements were carried out for short periods, 1 or 2 h, during which the densification of the deposited snow was negligible. Also, we grouped snowfall events based on similar hydrometeor characteristics. As a result, we were able to obtain not only the qualitative relationships between the main types of snow and snowfall density as reported by previous researchers, but also quantitative relationships between snowfall density and the CMF density introduced here. CMF density is defined as the ratio between mass and volume, assuming the diameter of a sphere is equal to the CMF size component. This quantitative relationship provides a means for more precise estimation of snowfall density based on snow type (hydrometeor characteristics), by using hydrometeor size and fall speed data to derive initial densities for numerical snowpack models, and the snow-to-liquid ratio for winter weather forecasting. In fact, we found that this method can more accurately estimate snowfall density compared with using meteorological elements, which is the method generally used in current snowpack models, even though some issues remain in parameterization for practical use. Transferability of the method developed in the temperate climate zone, where riming and aggregation are predominant, to other snowy areas is also an issue. However, the methodology presented in this study would be useful for other kinds of snow.

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Seroprevalence of Rift Valley fever and lumpy skin disease in African buffalo (Syncerus caffer) in the Kruger National Park and Hluhluwe-iMfolozi Park, South Africa

Journal of the South African Veterinary Association ◽

10.4102/jsava.v85i1.1075 ◽

2014 ◽

Vol 85 (1) ◽

Cited By ~ 20

Author(s):

Shamsudeen Fagbo ◽

Jacobus A.W. Coetzer ◽

Estelle H. Venter

Keyword(s):

Skin Disease ◽

Rift Valley ◽

National Park ◽

Rift Valley Fever ◽

Kruger National Park ◽

African Buffalo ◽

Neutralising Antibodies ◽

Valley Fever ◽

Lumpy Skin Disease ◽

Antibody Titres

Rift Valley fever and lumpy skin disease are transboundary viral diseases endemic in Africa and some parts of the Middle East, but with increasing potential for global emergence. Wild ruminants, such as the African buffalo (Syncerus caffer), are thought to play a role in the epidemiology of these diseases. This study sought to expand the understanding of the role of buffalo in the maintenance of Rift Valley fever virus (RVFV) and lumpy skin disease virus (LSDV) by determining seroprevalence to these viruses during an inter-epidemic period. Buffaloes from the Kruger National Park (n = 138) and Hluhluwe-iMfolozi Park (n = 110) in South Africa were sampled and tested for immunoglobulin G (IgG) and neutralising antibodies against LSDV and RVFV using an indirect enzyme-linked immunosorbent assay (I-ELISA) and the serum neutralisation test (SNT). The I-ELISA for LSDV and RVFV detected IgG antibodies in 70 of 248 (28.2%) and 15 of 248 (6.1%) buffaloes, respectively. Using the SNT, LSDV and RVFV neutralising antibodies were found in 5 of 66 (7.6%) and 12 of 57 (21.1%), respectively, of samples tested. The RVFV I-ELISA and SNT results correlated well with previously reported results. Of the 12 SNT RVFV-positive sera, three (25.0%) had very high SNT titres of 1:640. Neutralising antibody titres of more than 1:80 were found in 80.0% of the positive sera tested. The LSDV SNT results did not correlate with results obtained by the I-ELISA and neutralising antibody titres detected were low, with the highest (1:20) recorded in only two buffaloes, whilst 11 buffaloes (4.4%) had evidence of co-infection with both viruses. Results obtained in this study complement other reports suggesting a role for buffaloes in the epidemiology of these diseases during inter-epidemic periods.

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Defining the Relationship of Magnetohydrodynamic Voltages and Magnetic Field Strength

2017 Design of Medical Devices Conference ◽

10.1115/dmd2017-3401 ◽

2017 ◽

Author(s):

Kevin J. Wu ◽

T. Stan Gregory ◽

Michael C. Lastinger ◽

Brian Boland ◽

Zion Tsz Ho Tse

Keyword(s):

Magnetic Field ◽

Blood Flow ◽

Field Strength ◽

Aortic Arch ◽

Magnetic Field Strength ◽

Quantitative Relationship ◽

Solution Concentration ◽

Exercise Stress ◽

Induced Voltage ◽

The Relationship

The magnetohydrodynamic (MHD) effect is observed in flowing electrolytic fluids and their interactions with magnetic fields. The magnetic field (B0), when perpendicular with the electrolytic fluid flow (μ), causes the shift of the charged particles in the fluid to shift across the length of the vessel (L) normal to the plane of B0 and flow, creating a voltage (VMHD) observable through voltage potential measurements across the flow (Eqn. 1)[1].(1)VMHD=∫0Lu⇀×B0⇀·dL⇀In the medical field, this phenomenon is commonly encountered inside of a human body inside of an MRI machine (Fig. 1). The effect appears most prominently inside the aortic arch due to orientation and size, and is a large contributing factor to noise observed in intra-MRI ECGs [2, 3]. Traditionally, this MHD induced voltage (VMHD) was filtered out to obtain clean intra-MRI ECGs, but recent studies have shown that the VMHD induced in a vessel is related to the blood flow through it (stroke volume in the case of the aortic arch) [4]. Further proof of this relationship can be shown from the increase in VMHD measured from periphery blood vessels during periods of elevated heart rate from exercise stress, when compared to baseline state [5]. Previously, a portable device was built to utilize induced VMHD as an indicator of flow [6]. The device was capable of showing change in blood flow, utilizing a blood flow metric obtained from VMHD, however a quantitative relationship between VMHD and blood flow has yet to be established. This study aims to define the relationship between induced VMHD and magnetic field strength in a controlled setting. Through modulating the distance between a pair of magnets around a flow channel, we hope to better realize the relationship between magnetic field strength and induced VMHD with constant flow and electrolytic solution concentration.

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Quantitative Relationship between Strain and Acoustic Emission Response in Monitoring Fatigue Damage

Jurnal Teknologi ◽

10.11113/jt.v66.1349 ◽

2013 ◽

Vol 66 (1) ◽

Author(s):

M. Mohammad ◽

S. Abdullah ◽

N. Jamaludin ◽

O. Innayatullah

Keyword(s):

Acoustic Emission ◽

Failure Mechanism ◽

Fatigue Failure ◽

Quantitative Relationship ◽

Steel Specimen ◽

Cyclic Fatigue ◽

Steel Component ◽

Specific Data ◽

The Relationship ◽

Ae Signals

This study was carried out to investigate the relationship between the strain and acoustic emission (AE) signals, thus, to confirm the capability of AE technique to monitor the fatigue failure mechanism of a steel component. To achieve this goal, strain and AE signals were captured on the steel specimen during the cyclic fatigue test. Both signals were collected using specific data acquisition system by attaching the strain gauge and AE piezoelectric transducer simultaneously at the specimen during the test. The stress loading used for the test was set at 600 MPa, and the specimens were fabricated using the SAE 1045 carbon steel. The related parameters for both signals were determined at every 2000 seconds until the specimen failed. It was found that a meaningful correlation of all parameters, i.e. amplitude, kurtosis and energy, was established. Finally, all AE parameters are correlated with the damage values, which have been estimated using the Coffin-Manson model. Hence, it was suggested that the AE technique can be used as a monitoring tool for fatigue failure mechanism in a steel component.

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Experimental Study on Test Methods of the Intergranular Suction of Unsaturated Lateritic Soil

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.353-356.440 ◽

2013 ◽

Vol 353-356 ◽

pp. 440-445

Author(s):

Hua Lu ◽

Yang Wang ◽

Xiao Yan Wang ◽

Li Jun Hou ◽

Xin Zhao Jiang

Keyword(s):

Southern China ◽

Quantitative Relationship ◽

Test Methods ◽

Degree Of Saturation ◽

Lateritic Soil ◽

Test Results ◽

Empirical Parameter ◽

Pore Fluid Chemistry ◽

Unsaturated Condition ◽

The Relationship

This paper aims at the test methods of the suction between grains of lateritic soil which is widely distributed in southern China, and proposes the test methods and principles according to the variation of the suctions various components. This paper works over the relationship between the suction and the degree of saturation through tests, and also analyzes pore fluid chemistry influence on the suction between grains. The test results show that the test principles and methods are feasible. They also show that the quantitative relationship between the unsaturated soil’s shear strength and saturation (water content), and a new understanding of the physical meaning in unsaturated condition of X, which is a empirical parameter in the principle of Bishop‘s effective stress.

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