scholarly journals Dynamics of Neutralizing Antibody Responses Following Natural SARS-CoV-2 Infection and Correlation with Commercial Serologic Tests. A Reappraisal and Indirect Comparison with Vaccinated Subjects

Viruses ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2329
Author(s):  
Constant Gillot ◽  
Julien Favresse ◽  
Vincent Maloteau ◽  
Jean-Michel Dogné ◽  
Jonathan Douxfils
Keyword(s):  
Neutralization Test ◽  
Indirect Comparison ◽  
Neutralizing Antibody ◽  
Target Cells ◽  
Binding Assays ◽  
Post Vaccination ◽  
Neutralizing Capacity ◽  
Two Samples ◽  
Secure Environment

Neutralising antibodies (NAbs) represent the real source of protection against SARS-CoV-2 infections by preventing the virus from entering target cells. The gold standard in the detection of these antibodies is the plaque reduction neutralization test (PRNT). As these experiments must be done in a very secure environment, other techniques based on pseudoviruses: pseudovirus neutralization test (pVNT) or surrogate virus neutralization test (sVNT) have been developed. Binding assays, on the other hand, measure total antibodies or IgG, IgM, and IgA directed against one epitope of the SARS-CoV-2, independently of their neutralizing capacity. The aim of this study is to compare the performance of six commercial binding assays to the pVNT and sVNT. In this study, we used blood samples from a cohort of 62 RT-PCR confirmed COVID-19 patients. Based on the results of the neutralizing assays, adapted cut-offs for the binding assays were calculated. The use of these adapted cut-offs does not permit to improve the accuracy of the serological assays and we did not find an adapted cut-off able to improve the capacity of these tests to detect NAbs. For a part of the population, a longitudinal follow-up with at least two samples for the same patient was performed. From day 14 to day 291, more than 75% of the samples were positive for NAbs (n = 87/110, 79.1%). Interestingly, 6 months post symptoms onset, the majority of the samples (N = 44/52, 84.6%) were still positive for NAbs. This is in sharp contrast with the results we obtained 6 months post-vaccination in our cohort of healthcare workers who have received the two-dose regimens of BNT162b2. In this cohort of vaccinated subjects, 43% (n = 25/58) of the participants no longer exhibit NAbs activity 180 days after the administration of the first dose of BNT162b2.

scholarly journals Evaluation of six commercial SARS-CoV-2 serology assays detecting different antibodies for clinical testing and serosurveillance

2021 ◽  
Author(s):  
Suellen Nicholson ◽  
Theo Karapanagiotidis ◽  
Arseniy Khvorov ◽  
Celia Douros ◽  
Francesca Mordant ◽  
...  
Keyword(s):  
Cell Culture ◽  
Neutralization Test ◽  
Serological Test ◽  
Neutralizing Antibody ◽  
Neutralization Assay ◽  
Virus Neutralization Test ◽  
Virus Neutralization ◽  
Binding Assays ◽  
Humoral Immune ◽  
A Cell

Abstract Background Serological testing for SARS-CoV-2 complements nucleic acid tests for patient diagnosis and enables monitoring of population susceptibility to inform the COVID-19 pandemic response. It is important to understand the reliability of assays with different antigen or antibody targets to detect humoral immunity after SARS-CoV-2 infection and to understand how antibody (Ab) binding assays compare to those detecting neutralizing antibody (nAb), particularly as we move into the era of vaccines. Methods We evaluated the performance of six commercially available Enzyme-linked Immunosorbent Assays (ELISAs), including a surrogate virus neutralization test (sVNT), for detection of SARS-CoV-2 immunoglobulins (IgA, IgM, IgG), total or nAb. A result subset was compared to a cell culture-based microneutralisation (MN) assay. We tested sera from patients with prior RT-PCR confirmed SARS-CoV-2 infection, pre-pandemic sera and potential cross-reactive sera from patients with other non-COVID-19 acute infections. Results For sera collected > 14 days post-symptom onset, the assay achieving the highest sensitivity was the Wantai total Ab at 100% (95% confidence interval: 94.6-100) followed by 93.1% for Euroimmun NCP-IgG, 93.1% for GenScript sVNT, 90.3% for Euroimmun S1-IgG, 88.9% for Euroimmun S1-IgA and 83.3% for Wantai IgM. Specificity for the best performing assay was 99.5% for the Wantai total Ab and for the lowest performing assay was 97.1% for sVNT (as per IFU). The Wantai Total Ab had the best agreement with MN at 98% followed by Euroimmun S1-IgA, Euro NCP-IgG and sVNT (as per IFU) with (97%, 97% and 95% respectively) and Wantai IgM having the poorest agreement at 93%. Conclusion Performance characteristics of the SARS-CoV-2 serology assays detecting different antibody types are consistent with those found in previously published reports. Evaluation of the surrogate virus neutralization test in comparison to the Ab binding assays and a cell culture-based neutralization assay showed good result correlation between all assays. However correlation between the cell-based neutralization test and some assays detecting Ab’s not specifically involved in neutralization was higher than with the sVNT. This study demonstrates the reliability of different assays to detect the humoral immune response following SARS-CoV-2 infection, which can be used to optimise serological test algorithms for assessing antibody responses post SARS-CoV-2 infection or vaccination.

scholarly journals Neutralizing antibody titres to SARS-CoV-2 Omicron variant and wild-type virus in those with past infection or vaccinated or boosted with mRNA BNT162b2 or inactivated CoronaVac vaccines

2022 ◽  
Author(s):  
Malik Peiris ◽  
Samuel Cheng ◽  
Chris Ka Pun Mok ◽  
Yonna Leung ◽  
Susanna Ng ◽  
...  
Keyword(s):  
Protective Immunity ◽  
Neutralization Test ◽  
Neutralizing Antibody ◽  
Wild Type Virus ◽  
Wild Type ◽  
Past Infection ◽  
Post Vaccination ◽  
Antibody Titres ◽  
Duration Of Protection ◽  
Antibody Levels

Abstract Omicron, a novel SARS-CoV-2 variant has emerged and is rapidly becoming the dominant SARS-CoV-2 virus circulating globally. It is important to define reductions in virus neutralizing activity in serum of convalescent or vaccinated individuals to understand potential loss of protection from infection or re-infection. Two doses of BNT162b2 or CoronaVac vaccines provided little 50% plaque reduction neutralization test (PRNT50) antibody immunity against the Omicron variant, even at one-month post vaccination. Booster doses with BNT162b2 in those with two doses of either BNT162b2 or CoronaVac provided acceptable neutralizing immunity against Omicron variant at 1-month post-booster dose. However, three doses of BNT162b2 elicited higher levels of PRNT50 antibody to Omicron variant suggesting longer duration of protection. Convalescent from SARS-CoV-2 infection did not have protective PRNT50 antibody levels to Omicron, but a single dose of BNT162b2 vaccine provided protective immunity. Field vaccine-efficacy studies against Omicron variant against different vaccines are urgently needed.

scholarly journals Presence and short-term persistence of SARS-CoV-2 neutralizing antibodies in COVID-19 convalescent plasma donors.

2020 ◽  
Author(s):  
Kyle Annen ◽  
Thomas E Morrison ◽  
Melkon G DomBourian ◽  
Mary K McCarthy ◽  
Leah Huey ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Neutralization Test ◽  
Neutralizing Antibody ◽  
Considerable Variability ◽  
Binding Assays ◽  
Short Term ◽  
Live Virus ◽  
Donor Population ◽  
Antibody Titers ◽  
Focus Reduction

In March 2020, the FDA approved the use of COVID-19 convalescent plasma (CCP) as an investigational new drug for treatment of COVID-19. Since then, collection of CCP from COVID-19 recovered patients has been implemented in several donor centers across the country. Childrens Hospital Colorado rapidly put into practice a CCP collection protocol, necessitating the development and implementation of assays to evaluate SARS-CoV-2 antibodies in CCP units. We evaluated 87 separate units of CCP collected from 36 donors over two to four sequential donations using both antigen-binding assays for SARS-CoV-2 nucleoprotein and spike antigens, and a live virus focus reduction neutralization test (FRNT50). Our data shows that the majority of donors (83 percent) had a FRNT50 titer of 1/80 or greater, and 61 percent had a titer greater than or equal to 1/160, which meet the FDA criteria for acceptable CCP units. Additionally, our data indicates that analysis of antibodies to a single SARS-CoV-2 antigen is likely to miss a percentage of seroconverters. These individuals, however, tend to have neutralizing antibody titers of less than 1/80. Of note, there was considerable variability in the short term, sustained antibody response, measured by neutralizing antibody titers, among our donor population.

scholarly journals Rapid quantitative screening assay for SARS-CoV-2 neutralizing antibodies using HiBiT-tagged virus-like particles

2020 ◽  
Author(s):  
Kei Miyakawa ◽  
Sundararaj Stanleyraj Jeremiah ◽  
Norihisa Ohtake ◽  
Satoko Matsunaga ◽  
Yutaro Yamaoka ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Neutralization Test ◽  
Rapid Test ◽  
Neutralizing Antibody ◽  
Target Cells ◽  
Screening Assay ◽  
Nucleocapsid Proteins ◽  
Virus Like Particles ◽  
Virus Like Particle ◽  
Quantitative Screening

SARS-CoV-2 neutralizing antibodies confer protective immunity against reinfection. We have developed a rapid test for screening SARS-CoV-2 neutralization antibodies using genome-free virus-like particles incorporated with a small luciferase peptide, HiBiT. Their entry into LgBiT-expressing target cells reconstitutes NanoLuc luciferase readily detected by a luminometer. This newly developed HiBiT-tagged Virus-like particle-based Neutralization Test (hiVNT) can readily quantify SARS-CoV-2 neutralizing antibodies within three hours with a high-throughput in a low biosafety setting. Moreover, the neutralizing activity obtained from hiVNT was highly consistent with that measured by the conventional neutralization test using authentic SARS-CoV-2. Furthermore, antibody responses to both viral spike and nucleocapsid proteins correlated with the neutralization activity assessed by hiVNT. Our newly-developed hiVNT could be instrumental to survey individuals for the presence of functional neutralizing antibody against SARS-CoV-2.

scholarly journals Delayed neutralizing antibody response in the acute phase correlates with severe progression of COVID-19

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hitoshi Kawasuji ◽  
Yoshitomo Morinaga ◽  
Hideki Tani ◽  
Miyuki Kimura ◽  
Hiroshi Yamada ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Neutralization Test ◽  
Neutralizing Antibody ◽  
Pseudotyped Virus ◽  
Serum Samples ◽  
Neutralization Activity ◽  
Neutralizing Activity ◽  
Time Points ◽  
Moderate Disease ◽  
Activity Dynamics

AbstractAdaptive immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) dynamics remain largely unknown. The neutralizing antibody (NAb) levels in patients with coronavirus disease 2019 (COVID-19) are helpful for understanding the pathology. Using SARS-CoV-2 pseudotyped virus, serum sample neutralization values in symptomatic COVID-19 patients were measured using the chemiluminescence reduction neutralization test (CRNT). At least two sequential serum samples collected during hospitalization were analyzed to assess NAbs neutralizing activity dynamics at different time points. Of the 11 patients, four (36.4%), six (54.5%), and one (9.1%) had moderate, severe, and critical disease, respectively. Fifty percent neutralization (N50%-CRNT) was observed upon admission in 90.9% (10/11); all patients acquired neutralizing activity 2–12 days after onset. In patients with moderate disease, neutralization was observed at earliest within two days after symptom onset. In patients with severe-to-critical disease, neutralization activity increased, plateauing 9–16 days after onset. Neutralization activity on admission was significantly higher in patients with moderate disease than in patients with severe-to-critical disease (relative % of infectivity, 6.4% vs. 41.1%; P = .011). Neutralization activity on admission inversely correlated with disease severity. The rapid NAb response may play a crucial role in preventing the progression of COVID-19.

scholarly journals Continuous HIV-1 Escape from Autologous Neutralization and Development of Cross-Reactive Antibody Responses Characterizes Slow Disease Progression of Children

Vaccines ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 260
Author(s):  
Stefania Dispinseri ◽  
Mariangela Cavarelli ◽  
Monica Tolazzi ◽  
Anna Maria Plebani ◽  
Marianne Jansson ◽  
...  
Keyword(s):  
Disease Progression ◽  
Antibody Responses ◽  
Viral Escape ◽  
Target Cells ◽  
Transmitted Virus ◽  
Slow Progressors ◽  
Vaccine Antigens ◽  
Kinetics Of ◽  
Hiv 1

The antibodies with different effector functions evoked by Human Immunodeficiency Virus type 1 (HIV-1) transmitted from mother to child, and their role in the pathogenesis of infected children remain unresolved. So, too, the kinetics and breadth of these responses remain to be clearly defined, compared to those developing in adults. Here, we studied the kinetics of the autologous and heterologous neutralizing antibody (Nab) responses, in addition to antibody-dependent cellular cytotoxicity (ADCC), in HIV-1 infected children with different disease progression rates followed from close after birth and five years on. Autologous and heterologous neutralization were determined by Peripheral blood mononuclear cells (PBMC)- and TZMbl-based assays, and ADCC was assessed with the GranToxiLux assay. The reactivity to an immunodominant HIV-1 gp41 epitope, and childhood vaccine antigens, was assessed by ELISA. Newborns displayed antibodies directed towards the HIV-1 gp41 epitope. However, antibodies neutralizing the transmitted virus were undetectable. Nabs directed against the transmitted virus developed usually within 12 months of age in children with slow progression, but rarely in rapid progressors. Thereafter, autologous Nabs persisted throughout the follow-up of the slow progressors and induced a continuous emergence of escape variants. Heterologous cross-Nabs were detected within two years, but their subsequent increase in potency and breadth was mainly a trait of slow progressors. Analogously, titers of antibodies mediating ADCC to gp120 BaL pulsed target cells increased in slow progressors during follow-up. The kinetics of antibody responses to the immunodominant viral antigen and the vaccine antigens were sustained and independent of disease progression. Persistent autologous Nabs triggering viral escape and an increase in the breadth and potency of cross-Nabs are exclusive to HIV-1 infected slowly progressing children.

scholarly journals Serially measured cytokines and cytokine receptors in relation to clinical outcome in patients with stable heart failure

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
E Bouwens ◽  
A Schuurman ◽  
K.M Akkerhuis ◽  
S.J Baart ◽  
K Caliskan ◽  
...  
Keyword(s):  
Heart Failure ◽  
Clinical Outcome ◽  
Primary Endpoint ◽  
Nyha Class ◽  
Cytokine Receptors ◽  
Funding Source ◽  
Compensatory Mechanism ◽  
Blood Samples ◽  
Two Samples

Abstract Background Activation of the inflammatory response in heart failure (HF) may initially serve as a compensatory mechanism. However, on the longer term, this physiological phenomenon can become disadvantageous. Temporal patterns of inflammatory proteins other than CRP have not yet been investigated in patients with stable HF. Purpose We aimed to evaluate the association of 17 serially measured cytokines and cytokine receptors with clinical outcome in patients with stable heart failure. Methods In 263 patients, 1984 serial, tri-monthly blood samples were collected during a median follow-up of 2.2 (IQR: 1.4–2.5) years. The primary endpoint (PE) composed of cardiovascular mortality, HF-hospitalization, heart transplantation, and LVAD. We selected baseline blood samples in all patients, as well as the two samples closest to the primary endpoint, and the last sample available in event-free patients. Thus, in 567 samples we measured 17 cytokines and cytokine receptors using the Olink Proteomics Cardiovascular III multiplex assay. Associations between biomarkers and PE were investigated by joint modelling. Results Median age was 68 (IQR: 59–76) years, with 72% men, 74% NYHA class I-II and a median ejection fraction of 30% (23–38%). 70 patients reached a PE. After adjustment for clinical characteristics (age, sex, diabetes, atrial fibrillation, NYHA class at baseline, diuretics and systolic blood pressure), 7 biomarkers were associated with the PE (Figure). Interleukin-1 receptor type 1 (IL1RT1) showed the strongest association: HR 2.65 [95% CI: 1.78–4.21]) per standard deviation change in level (NPX) at any point in time during follow-up, followed by Tumor necrosis factor receptor 1 (TNF-R1): 2.25 [1.66–3.08], and C-X-C motif chemokine 16 (CXCL16): 2.18 [1.59–3.04]. After adjustment for baseline N-terminal pro–B-type natriuretic peptide, high-sensitive troponin T and C-reactive protein however, only IL1RT1 and TNF-R1 remained significantly associated with the PE. Conclusion Repeatedly measured levels of several cytokines and cytokine receptors are independently associated with clinical outcome in stable HF patients. These results suggest that repeated measurements of these biomarkers, in addition to established cardiac biomarkers, may contribute to personalized risk assessment and herewith better identify high-risk patients. Figure 1. Associations between levels of cytokines and cytokine receptors and the primary endpoint. Funding Acknowledgement Type of funding source: Other. Main funding source(s): This work was supported by the Jaap Schouten Foundation and the Noordwest Academie.

scholarly journals Role of CXC chemokine receptor type 4 as a lactoferrin receptor

2017 ◽  
Vol 95 (1) ◽  
pp. 57-63 ◽  
Author(s):  
Yoshiharu Takayama ◽  
Reiji Aoki ◽  
Ryo Uchida ◽  
Atsushi Tajima ◽  
Ayako Aoki-Yoshida
Keyword(s):  
Biological Activities ◽  
Ldl Receptor ◽  
Neutralizing Antibody ◽  
Human Keratinocytes ◽  
Akt Signaling ◽  
Target Cells ◽  
Bovine Lactoferrin ◽  
Lactoferrin Receptor ◽  
Stromal Cell Derived Factor ◽  
The Many

Lactoferrin exerts its biological activities by interacting with receptors on target cells, including LDL receptor-related protein-1 (LRP-1/CD91), intelectin-1 (omentin-1), and Toll-like receptor 4 (TLR4). However, the effects mediated by these receptors are not sufficient to fully explain the many functions of lactoferrin. C-X-C-motif cytokine receptor 4 (CXCR4) is a ubiquitously expressed G-protein coupled receptor for stromal cell-derived factor-1 (SDF-1/CXCL12). Lactoferrin was found to be as capable as SDF-1 in blocking infection by an HIV variant that uses CXCR4 as a co-receptor (X4-tropic HIV), suggesting that lactoferrin interacts with CXCR4. We addressed whether CXCR4 acts as a lactoferrin receptor using HaCaT human keratinocytes and Caco-2 human intestinal cells. We found that bovine lactoferrin interacted with CXCR4-containing lipoparticles, and that this interaction was not antagonized by SDF-1. In addition, activation of Akt in response to lactoferrin was abrogated by AMD3100, a small molecule inhibitor of CXCR4, or by a CXCR4-neutralizing antibody, suggesting that CXCR4 functions as a lactoferrin receptor able to mediate activation of the PI3K–Akt signaling pathway. Lactoferrin stimulation mimicked many aspects of SDF-1-induced CXCR4 activity, including receptor dimerization, tyrosine phosphorylation, and ubiquitination. Cycloheximide chase assays indicated that turnover of CXCR4 was accelerated in response to lactoferrin. These results indicate that CXCR4 is a potent lactoferrin receptor that mediates lactoferrin-induced activation of Akt signaling.

scholarly journals The Use of Heap Bioleaching as a Pre-Treatment for Platinum Group Metal Leaching

2017 ◽  
Vol 262 ◽  
pp. 151-154
Author(s):  
James M. Mwase ◽  
Jochen Petersen
Keyword(s):  
Platinum Group Metal ◽  
Metal Leaching ◽  
Flotation Concentrate ◽  
Group Metal ◽  
Two Samples ◽  
Heap Bioleaching ◽  
Mineral Recovery ◽  
The Difference ◽  
Pre Treatment

Two samples, a Platreef flotation concentrate and coarse ore (<6 mm), were column bioleached at 65°C using a culture dominated by Metallosphaera hakonensis. Based on solution assays, extractions in excess of 90% Cu and Ni were achieved from the flotation concentrate, while from the coarse ore 96% Cu and 67% Ni extractions were achieved. The difference in extraction levels and leaching patterns despite identical conditions used for both samples is discussed, as is the performance of the samples during a follow-up leach step using cyanide to extract the PGMs in a separate column leach experiment. While the recovery of Pd and Au was excellent during these steps, recovery of Pt was limited to 35% after 45 days for the concentrate and 56% after 60 days for the whole ore material, primarily due to the presence of a refractory Pt mineral. Recovery from a concentrate without pre-treatment was substantially lower.

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