scholarly journals Nucleocapsid antibody positivity as a marker of past SARS-CoV-2 infection in population serosurveillance studies: impact of variant, vaccination, and choice of assay cut-off

2021 ◽  
Author(s):  
Heather J Whitaker ◽  
Charlotte Gower ◽  
Ashley D Otter ◽  
Ruth Simmons ◽  
Freja Kirsebom ◽  
...  
Keyword(s):  
Surveillance Studies ◽  
Assay Performance ◽  
Antibody Titres ◽  
Antibody Positivity ◽  
Serological Surveillance ◽  
Alpha Variant

Serological surveillance studies sometimes use presence of anti-nucleocapsid antibody as a marker of natural SARS-CoV-2 infection. We explore seroconversion rates and antibody titres following Alpha and Delta variant infections, and vaccine breakthrough infections. We find lower seroconversion rates particularly following Alpha-variant vaccine breakthrough infections. We re-evaluate assay performance with a mix of past waned infections and recent breakthrough infections, that is relevant to current serological surveillance.

scholarly journals Seroprevalence of SARS-CoV-2 antibodies in children - A prospective multicentre cohort study.

2020 ◽  
Author(s):  
Thomas Waterfield ◽  
Chris Watson ◽  
Rebecca Moore ◽  
Kathryn Ferris ◽  
Claire Tonry ◽  
...  
Keyword(s):  
Cohort Study ◽  
Gastrointestinal Symptoms ◽  
Contact Fatigue ◽  
Final Analysis ◽  
Molecular Testing ◽  
Antibody Testing ◽  
Sense Of Smell ◽  
Antibody Titres ◽  
Previous Infection ◽  
Antibody Positivity

Background Studies based on molecular testing of oral/nasal swabs underestimate SARS-CoV-2 infection due to issues with test sensitivity and timing of testing. The objective of this study was to report the presence of SARS-CoV-2 antibodies, consistent with previous infection, and to report the symptomatology of infection in children. Design This multicentre observational cohort study, conducted between 16th April - 3rd July 2020 at 5 UK sites, aimed to recruit 900 children aged 2 to 15 years of age. Participants provided blood samples for SARS-CoV-2 antibody testing and data were gathered regarding unwell contacts and symptoms. Results 1007 participants were enrolled, and 992 were included in the final analysis. The median age of participants was 10.1 years. There were 68 (6.9%) participants with positive SARS-CoV-2 antibody tests indicative of previous SARS-CoV-2 infection. Of these, 34/68 (50%) reported no symptoms. The presence of antibodies and the mean antibody titre was not influenced by age. Following multivariate analysis 4 independent variables were identified as significantly associated with SARS-CoV-2 infection. These were: known infected household contact; fatigue; gastrointestinal symptoms; and changes in sense of smell or taste. Discussion In this study children demonstrated similar antibody titres in response to SARS-CoV-2 irrespective of age. The symptoms of SARS-CoV-2 infection in children were subtle but of those reported, fatigue, gastrointestinal symptoms and changes in sense of smell or taste were most strongly associated with antibody positivity. Registration This study was registered at https://www.clinicaltrials.gov (trial registration: NCT04347408) on the 15/04/2020.

Influence of interferon-beta therapy switching on neutralizing antibody titres: results from the Austrian Switch Study

2009 ◽  
Vol 15 (12) ◽  
pp. 1481-1488 ◽  
Author(s):  
Claudia Gneiss ◽  
Pia-Maria Koudouovoh-Tripp ◽  
Stefan Ropele ◽  
Thaddäus Gotwald ◽  
Rainer Ehling ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Interferon Beta ◽  
Previous Treatment ◽  
Neutralizing Antibody ◽  
High Dose ◽  
Continuous Therapy ◽  
High Dose Methylprednisolone ◽  
Antibody Titres ◽  
Antibody Positivity ◽  
To Receive

Neutralizing antibodies against interferon-beta are associated with a reduction of the efficacy of this drug. Continuing treatment leads to a decline or even loss of neutralizing antibodies over years. No strategies are currently available to shorten the period of neutralizing antibody positivity. The objective of this study was to investigate the effect of switching between high and low immunogenic interferon-beta products on neutralising antibody titres. Twenty-four patients treated with the subcutaneously administered interferon-beta 1b or 1a and high titres of neutralizing antibodies were included. At baseline interferon-beta therapy was interrupted for 3 months and two pulses of high dose methylprednisolone were applied. Patients were then randomized to receive either the previous interferon-beta preparation or the low immunogenic intramuscular interferon-beta 1a. The primary end-point was the change of neutralizing antibody titres 12 months after randomization. Twelve patients were switched to interferon-beta 1a intramuscularly and 12 patients remained on previous treatment. Median neutralizing antibody titres were 846 NU at baseline and 196 NU at the end of the study. The median change of neutralizing antibody titres did not differ significantly between therapy switchers and non-switchers. Baseline and final neutralizing antibody titres correlated significantly. In conclusion, neither switching nor continuous therapy with any subcutaneous interferon-beta preparation significantly changed neutralizing antibody titres.

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

Viruses ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 247
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

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.

scholarly journals Stringent thresholds for SARS-CoV-2 IgG assays result in under-detection of cases reporting loss of taste/smell

2020 ◽  
Author(s):  
David W Eyre ◽  
Sheila F Lumley ◽  
Denise O'Donnell ◽  
Nicole E Stoesser ◽  
Philippa C Matthews ◽  
...  
Keyword(s):  
Asymptomatic Infection ◽  
Negative Results ◽  
Diagnostic Thresholds ◽  
Assay Performance ◽  
Hospitalised Patients ◽  
Antibody Assays ◽  
Antibody Titres ◽  
Chemiluminescent Microparticle Immunoassay ◽  
Test Probability ◽  
Abbott Architect

Thresholds for SARS-CoV-2 antibody assays have typically been determined using samples from symptomatic, often hospitalised, patients. Assay performance following mild/asymptomatic infection is unclear. We assessed IgG responses in asymptomatic healthcare workers with a high pre-test probability of Covid-19, e.g. 807/9292(8.9%) reported loss of smell/taste. The proportion reporting anosmia/ageusia increased at antibody titres below diagnostic thresholds for both an in-house ELISA and the Abbott Architect chemiluminescent microparticle immunoassay (CMIA): 424/903(47%) reported anosmia/ageusia with a positive ELISA, 59/387(13.2%) with high-negative titres, and 324/7943(4.1%) with low-negative results. Adjusting for the proportion of staff reporting anosmia/ageusia suggests the sensitivity of both assays is lower than previously reported: Oxford ELISA 90.8% (95%CI 86.1-92.1%) and Abbott CMIA 80.9% (77.5-84.3%). However, the sensitivity may be lower if some anosmia/ageusia in those with low-negative titres is Covid-19-associated. Samples from individuals with mild/asymptomatic infection should be included in SARS-CoV-2 immunoassay evaluations. Reporting equivocal SARS-CoV-2 antibody results should be considered.

scholarly journals Prevalence of serum N-methyl-d-aspartate receptor autoantibodies in refractory psychosis

2015 ◽  
Vol 206 (2) ◽  
pp. 164-165 ◽  
Author(s):  
Katherine Beck ◽  
John Lally ◽  
Sukhwinder S. Shergill ◽  
Michael A. P. Bloomfield ◽  
James H. MacCabe ◽  
...  
Keyword(s):  
Point Prevalence ◽  
Acute Psychosis ◽  
Aspartate Receptor ◽  
Antibody Titres ◽  
Antibody Positivity ◽  
Treatment Refractory

SummaryN-methyl-d-aspartate receptor (NMDA-R) autoantibodies have been reported in people with acute psychosis. We hypothesised that their presence may be implicated in the aetiology of treatment-refractory psychosis. We sought to ascertain the point prevalence of NMDA-R antibody positivity in patients referred to services for treatment-refractory psychosis. We found that 3 (7.0%) of 43 individuals had low positive NMDA-R antibody titres. This suggests that NMDA-R autoantibodies are unlikely to account for a large proportion of treatment-refractory psychosis.

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

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.

scholarly journals A 1958 Isolate of Kedougou Virus (KEDV) from Ndumu, South Africa, Expands the Geographic and Temporal Range of KEDV in Africa

Viruses ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1368
Author(s):  
Petrus Jansen van Vuren ◽  
Rhys Parry ◽  
Alexander A. Khromykh ◽  
Janusz T. Paweska
Keyword(s):  
South Africa ◽  
Amino Acid ◽  
Complete Genome ◽  
Central African Republic ◽  
Amino Acid Identity ◽  
Diagnostic Assay ◽  
Acid Identity ◽  
Surveillance Studies ◽  
Kwazulu Natal ◽  
Serological Surveillance

The mosquito-borne flavivirus, Kedougou virus (KEDV), first isolated in Senegal in 1972, is genetically related to dengue, Zika (ZIKV) and Spondweni viruses (SPOV). Serological surveillance studies in Senegal and isolation of KEDV in the Central African Republic indicate occurrence of KEDV infections in humans, but to date, no disease has been reported. Here, we assembled the coding-complete genome of a 1958 isolate of KEDV from a pool of Aedes circumluteolus mosquitoes collected in Ndumu, KwaZulu-Natal, South Africa. The AR1071 Ndumu KEDV isolate bears 80.51% pairwise nucleotide identity and 93.34% amino acid identity with the prototype DakAar-D1470 strain and was co-isolated with SPOV through intracerebral inoculation of suckling mice and passage on VeroE6 cells. This historical isolate expands the known geographic and temporal range of this relatively unknown flavivirus, aiding future temporal phylogenetic calibration and diagnostic assay refinement.

scholarly journals Seroprevalence of SARS-CoV-2 antibodies in children: a prospective multicentre cohort study

2020 ◽  
pp. archdischild-2020-320558 ◽  
Author(s):  
Thomas Waterfield ◽  
Chris Watson ◽  
Rebecca Moore ◽  
Kathryn Ferris ◽  
Claire Tonry ◽  
...  
Keyword(s):  
Cohort Study ◽  
Multivariable Analysis ◽  
Gastrointestinal Symptoms ◽  
Final Analysis ◽  
Molecular Testing ◽  
Antibody Testing ◽  
Sense Of Smell ◽  
Antibody Titres ◽  
Previous Infection ◽  
Antibody Positivity

BackgroundStudies based on molecular testing of oral/nasal swabs underestimate SARS-CoV-2 infection due to issues with test sensitivity, test timing and selection bias. The objective of this study was to report the presence of SARS-CoV-2 antibodies, consistent with previous infection.DesignThis multicentre observational cohort study, conducted between 16 April to 3 July 2020 at 5 UK sites, recruited children of healthcare workers, aged 2–15 years. Participants provided blood samples for SARS-CoV-2 antibody testing and data were gathered regarding unwell contacts and symptoms.Results1007 participants were enrolled, and 992 were included in the final analysis. The median age of participants was 10·1 years. There were 68 (6.9%) participants with positive SARS-CoV-2 antibody tests indicative of previous SARS-CoV-2 infection. Of these, 34/68 (50%) reported no symptoms prior to testing. The presence of antibodies and the mean antibody titre was not influenced by age. Following multivariable analysis four independent variables were identified as significantly associated with SARS-CoV-2 seropositivity: known infected household contact OR=10.9 (95% CI 6.1 to 19.6); fatigue OR=16.8 (95% CI 5.5 to 51.9); gastrointestinal symptoms OR=6.6 (95% CI 3.0 to 13.8); and changes in sense of smell or taste OR=10.0 (95% CI 2.4 to 11.4).DiscussionChildren demonstrated similar antibody titres in response to SARS-CoV-2 irrespective of age. Fatigue, gastrointestinal symptoms and changes in sense of smell or taste were the symptoms most strongly associated with SARS-CoV-2 antibody positivity.Trial registration numberNCT0434740.

Serological surveillance studies confirm the Rift Valley fever virus free status in South Korea

2015 ◽  
Vol 47 (7) ◽  
pp. 1427-1430 ◽  
Author(s):  
Hyun Joo Kim ◽  
Jee-Yong Park ◽  
Hye-Young Jeoung ◽  
Jung-Yong Yeh ◽  
Yun-Sang Cho ◽  
...  
Keyword(s):  
South Korea ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Fever Virus ◽  
Valley Fever ◽  
Surveillance Studies ◽  
Serological Surveillance ◽  
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