Serological Analysis of New York City COVID19 Convalescent Plasma Donors

AbstractBackgroundThe development of neutralizing antibodies (NAbs) against SARS-CoV-2, following infection or vaccination, is likely to be critical for the development of sufficient population immunity to drive cessation of the COVID19 pandemic. A large number of serologic tests, platforms and methodologies are being employed to determine seroprevalence in populations to select convalescent plasmas for therapeutic trials, and to guide policies about reopening. However, these tests have substantially variable sensitivity and specificity, and their ability to quantitatively predict levels of NAbs is unknown.MethodsWe determined levels of antibodies in convalescent plasma using commercially available SARS-CoV- 2 detection tests and in-house ELISA assays and correlated those measurements with neutralization activity measured using pseudotyped virus particles, which offer the most informative assessment of antiviral activity of patient sera against viral infection.FindingsOur data show that a large proportion of convalescent plasma samples have modest antibody levels and that commercially available tests have varying degrees of accuracy in predicting neutralizing activity. Nevertheless, we found particular commercially available tests are capable of accurately measuring levels of antibodies that strongly correlate with neutralization assays.InterpretationOur findings imply that SARS-CoV-2 convalescent plasma donors have a wide range of antibody concentrations. At present it is unclear how antibody acquisition, particularly for low titer individuals, might afford future immunity to SARS-CoV-2. Further research will be required to determine the minimum threshold of antibody and neutralization activity necessary to accurately predict immunity. Correlation of clinical antibody tests with neutralization activity in this study could serve as a valuable ‘roadmap’ to guide the choice and interpretation of serological tests for SARS-CoV-2.FundingNIH NIAID, R01AI78788 (to TH) and R37AI64003 (to PDB)

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Serological Assays Estimate Highly Variable SARS-CoV-2 Neutralizing Antibody Activity in Recovered COVID-19 Patients

Journal of Clinical Microbiology ◽

10.1128/jcm.02005-20 ◽

2020 ◽

Vol 58 (12) ◽

Cited By ~ 12

Author(s):

Larry L. Luchsinger ◽

Brett P. Ransegnola ◽

Daniel K. Jin ◽

Frauke Muecksch ◽

Yiska Weisblum ◽

...

Keyword(s):

New York ◽

Neutralizing Antibodies ◽

Neutralizing Antibody ◽

Pseudotyped Virus ◽

Antibody Activity ◽

Plasma Samples ◽

Serological Tests ◽

Population Immunity ◽

Therapeutic Trials ◽

Antibody Levels

ABSTRACT The development of neutralizing antibodies (NAbs) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) following infection or vaccination is likely to be critical for the development of sufficient population immunity to drive cessation of the coronavirus disease of 2019 (COVID-19) pandemic. A large number of serologic tests, platforms, and methodologies are being employed to determine seroprevalence in populations to select convalescent plasma samples for therapeutic trials and to guide policies about reopening. However, the tests have substantial variations in sensitivity and specificity, and their ability to quantitatively predict levels of NAbs is unknown. We collected 370 unique donors enrolled in the New York Blood Center Convalescent Plasma Program between April and May of 2020. We measured levels of antibodies in convalescent plasma samples using commercially available SARS-CoV-2 detection tests and in-house enzyme-linked immunosorbent assays (ELISAs) and correlated serological measurements with NAb activity measured using pseudotyped virus particles, which offer the most informative assessment of antiviral activity of patient sera against viral infection. Our data show that a large proportion of convalescent plasma samples have modest antibody levels and that commercially available tests have various degrees of accuracy in predicting NAb activity. We found that the Ortho anti-SARS-CoV-2 total Ig and IgG high-throughput serological assays (HTSAs) and the Abbott SARS-CoV-2 IgG assay quantify levels of antibodies that strongly correlate with the results of NAb assays and are consistent with gold standard ELISA results. These findings provide immediate clinical relevance to serology results that can be equated to NAb activity and could serve as a valuable roadmap to guide the choice and interpretation of serological tests for SARS-CoV-2.

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Effects of Spike Mutations in SARS-CoV-2 Variants of Concern on Human or Animal ACE2-Mediated Virus Entry and Neutralization

10.1101/2021.08.25.457627 ◽

2021 ◽

Author(s):

Yunjeong Kim ◽

Natasha N Gaudreault ◽

David A Meekins ◽

Krishani D Perera ◽

Dashzeveg Bold ◽

...

Keyword(s):

Viral Entry ◽

Neutralizing Antibodies ◽

Animal Species ◽

Virus Entry ◽

Neutralizing Antibody ◽

Protein S ◽

Pseudotyped Virus ◽

S Protein ◽

Viral Neutralization ◽

Wide Range

SARS-CoV-2 is a zoonotic agent capable of infecting humans and a wide range of animal species. Over the duration of the pandemic, mutations in the SARS-CoV-2 Spike protein (S) have arisen in circulating viral populations, culminating in the spread of several variants of concern (VOC) with varying degrees of altered virulence, transmissibility, and neutralizing antibody escape. In this study, we employed lentivirus-based pseudotyped viruses that express specific SARS-CoV-2 S protein substitutions and cell lines that stably express ACE2 from nine different animal species to gain insights into the effects of VOC mutations on viral entry and antibody neutralization capability. All animal ACE2 receptors tested, except mink, support viral cell entry for pseudoviruses expressing the parental (prototype Wuhan-1) S at levels comparable to human ACE2. Most single S substitutions (e.g., 452R, 478K, 501Y) did not significantly change virus entry, although 614G and 484K resulted in a decreased efficiency in viral entry. Conversely, combinatorial VOC substitutions in the S protein were associated with significantly increased entry capacity of pseudotyped viruses compared to that of the parental Wuhan-1 pseudotyped virus. Similarly, infection studies using live ancestral (USA-WA1/2020), Alpha, and Beta SARS-CoV-2 viruses in hamsters revealed a higher replication potential for the Beta variant compared to the ancestral prototype virus. Moreover, neutralizing titers in sera from various animal species, including humans, were significantly reduced by single substitutions of 484K or 452R, double substitutions of 501Y-484K, 452R-484K and 452R-478K and the triple substitution of 501Y-484K-417N, suggesting that 484K and 452R are particularly important for evading neutralizing antibodies in human, cat, and rabbit sera. Cumulatively, this study reveals important insights into the host range of SARS-CoV-2 and the effect of recently emergent S protein substitutions on viral entry, virus replication and antibody-mediated viral neutralization.

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Neutralizing Antibodies and Persistence of Immunity following Anthrax Vaccination

Clinical and Vaccine Immunology ◽

10.1128/cvi.13.2.208-213.2006 ◽

2006 ◽

Vol 13 (2) ◽

pp. 208-213 ◽

Cited By ~ 17

Author(s):

James F. Hanson ◽

Sarah C. Taft ◽

Alison A. Weiss

Keyword(s):

Neutralizing Antibodies ◽

Protective Antigen ◽

Colorimetric Assay ◽

Lethal Factor ◽

Neutralization Activity ◽

Anthrax Vaccine ◽

Edema Factor ◽

Low Levels ◽

Antibody Levels ◽

Toxic Components

ABSTRACT Anthrax toxin consists of protective antigen (PA) and two toxic components, lethal factor (LF) and edema factor (EF). PA binds to mammalian cellular receptors and delivers the toxic components to the cytoplasm. PA is the primary antigenic component of the current anthrax vaccine. Immunity is due to the generation of antibodies that prevent the PA-mediated internalization of LF and EF. In this study, we characterized sera obtained from vaccinated military personnel. Anthrax vaccine is administered in a series of six injections at 0, 2, and 4 weeks and 6, 12, and 18 months, followed by annual boosters. The vaccination histories of the subjects were highly varied; many subjects had not completed the entire series, and several had not received annual boosters. We developed a simple colorimetric assay using alamarBlue dye to assess the antibody-mediated neutralization of LF-mediated toxicity to the J774A.1 murine macrophage cell line. Recently vaccinated individuals had high antibody levels and neutralizing activity. One individual who had not been boosted for 5 years had low immunoglobulin G antibody levels but a detectable neutralization activity, suggesting that this individual produced low levels of very active antibodies.

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Corona Virus Disease-19 serology, inflammatory markers, hospitalizations, case finding, and aging

PLoS ONE ◽

10.1371/journal.pone.0252818 ◽

2021 ◽

Vol 16 (6) ◽

pp. e0252818

Author(s):

Ernst J. Schaefer ◽

Latha Dulipsingh ◽

Florence Comite ◽

Jessica Jimison ◽

Martin M. Grajower ◽

...

Keyword(s):

Inflammatory Markers ◽

Neutralizing Antibodies ◽

Virus Disease ◽

Neutralizing Antibody ◽

Case Finding ◽

Immunoglobulin M ◽

Antibody Testing ◽

Wide Range ◽

Older Subjects ◽

Antibody Levels

Most deaths from severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection occur in older subjects. We assessed the utility of serum inflammatory markers interleukin-6 (IL-6), C reactive protein (CRP), and ferritin (Roche, Indianapolis, IN), and SARS-CoV-2 immunoglobulin G (IgG), immunoglobulin M (IgM), and neutralizing antibodies (Diazyme, Poway, CA). In controls, non-hospitalized subjects, and hospitalized subjects assessed for SARS-CoV-2 RNA (n = 278), median IgG levels in arbitrary units (AU)/mL were 0.05 in negative subjects, 14.83 in positive outpatients, and 30.61 in positive hospitalized patients (P<0.0001). Neutralizing antibody levels correlated significantly with IgG (r = 0.875; P<0.0001). Having combined values of IL-6 ≥10 pg/mL and CRP ≥10 mg/L occurred in 97.7% of inpatients versus 1.8% of outpatients (odds ratio 3,861, C statistic 0.976, P = 1.00 x 10−12). Antibody or ferritin levels did not add significantly to predicting hospitalization. Antibody testing in family members and contacts of SARS-CoV-2 RNA positive cases (n = 759) was invaluable for case finding. Persistent IgM levels were associated with chronic COVID-19 symptoms. In 81,624 screened subjects, IgG levels were positive (≥1.0 AU/mL) in 5.21%, while IgM levels were positive in 2.96% of subjects. In positive subjects median IgG levels in AU/mL were 3.14 if <30 years of age, 4.38 if 30–44 years of age, 7.89 if 45–54 years of age, 9.52 if 55–64 years of age, and 10.64 if ≥65 years of age (P = 2.96 x 10−38). Our data indicate that: 1) combined IL-6 ≥10 pg/mL and CRP ≥10 mg/L identify SARS-CoV-2 positive subjects requiring hospitalization; 2) IgG levels were significantly correlated with neutralizing antibody levels with a wide range of responses; 3) IgG levels have significant utility for case finding in exposed subjects; 4) persistently elevated IgM levels are associated with chronic symptoms; and 5) IgG levels are significantly higher in positive older subjects than their younger counterparts.

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The SARS-CoV-2 spike L452R-E484Q co-variant in the Indian B.1.617 strain Showed Significant Reduction in the Neutralization Activity of Immune Sera

Precision Clinical Medicine ◽

10.1093/pcmedi/pbab016 ◽

2021 ◽

Author(s):

Gen Li ◽

Zhongcheng Zhou ◽

Peng Du ◽

Meixing Yu ◽

Ning Li ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Vaccine Development ◽

Vaccination Strategy ◽

Pseudotyped Virus ◽

Natural Evolution ◽

Neutralization Activity ◽

Health Authorities ◽

Recombinant Receptor ◽

The Impact ◽

Biologic Factors

Abstract To assess the impact of the key non-synonymous amino acid substitutions in the RBD of the spike protein of SARS-CoV-2 variant B.1.617.1 (dominant variant identified in the current India outbreak) on the infectivity and neutralization activities of the immune sera, L452R and E484Q (L452R-E484Q, “co-variant”) pseudotyped virus was constructed (with the D614G background). The impact on the binding with the neutralizing antibodies was also assessed by an ELISA assay. Pseudotyped virus carrying a L452R-E484Q co-variant showed a comparable infectivity compared with D614G. However, there was a significant reduction in the neutralization activity of the immune sera from non-human primates vaccinated with a recombinant Receptor binding domain (RBD) protein, convalescent patients, and healthy vaccinees vaccinated with an mRNA vaccine. In addition, there was a reduction in the binding of L452R-E484Q-D614G protein to the antibodies of the immune sera from vaccinated non-human primates. These results highlight the interplay between infectivity and other biologic factors involved in the natural evolution of SARS-CoV-2. Reduced neutralization activities against the L452R-E484Q co-variant will have impact to the health authorities planning and implications to the vaccination strategy/new vaccine development.

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Role of the E2 Hypervariable Region (HVR1) in the Immunogenicity of a Recombinant Hepatitis C Virus Vaccine

Journal of Virology ◽

10.1128/jvi.02141-17 ◽

2018 ◽

Vol 92 (11) ◽

Cited By ~ 13

Author(s):

John L. M. Law ◽

Michael Logan ◽

Jason Wong ◽

Juthika Kundu ◽

Darren Hockman ◽

...

Keyword(s):

Hepatitis C Virus ◽

Hepatitis C ◽

Neutralizing Antibodies ◽

Hypervariable Region ◽

Vaccine Antigen ◽

Current Evidence ◽

Pseudotyped Virus ◽

Wild Type ◽

Neutralization Activity ◽

Neutralizing Epitopes

ABSTRACTCurrent evidence supports a protective role for virus-neutralizing antibodies in immunity against hepatitis C virus (HCV) infection. Many cross-neutralizing monoclonal antibodies have been identified. These antibodies have been shown to provide protection or to clear infection in animal models. Previous clinical trials have shown that a gpE1/gpE2 vaccine can induce antibodies that neutralize thein vitroinfectivity of all the major cell culture-derived HCV (HCVcc) genotypes around the world. However, cross-neutralization appeared to favor certain genotypes, with significant but lower neutralization against others. HCV may employ epitope masking to avoid antibody-mediated neutralization. Hypervariable region 1 (HVR1) at the amino terminus of glycoprotein E2 has been shown to restrict access to many neutralizing antibodies. Consistent with this, other groups have reported that recombinant viruses lacking HVR1 are hypersensitive to neutralization. It has been proposed that gpE1/gpE2 lacking this domain could be a better vaccine antigen to induce broadly neutralizing antibodies. In this study, we examined the immunogenicity of recombinant gpE1/gpE2 lacking HVR1 (ΔHVR1). Our results indicate that wild-type (WT) and ΔHVR1 gpE1/gpE2 antigens induced antibodies targeting many well-characterized cross-genotype-neutralizing epitopes. However, while the WT gpE1/gpE2 vaccine can induce cross-genotype protection against various genotypes of HCVcc and/or HCV-pseudotyped virus (HCVpp), antisera from ΔHVR1 gpE1/gpE2-immunized animals exhibited either reduced homologous neutralization activity compared to that of the WT or heterologous neutralization activity similar to that of the WT. These data suggest that ΔHVR1 gpE1/gpE2 is not a superior vaccine antigen. Based on previously reported chimpanzee protection data using WT gpE1/gpE2 and our current findings, we are preparing a combination vaccine including wild-type recombinant gpE1/gpE2 for clinical testing in the future.IMPORTANCEAn HCV vaccine is an unmet medical need. Current evidence suggests that neutralizing antibodies play an important role in virus clearance, along with cellular immune responses. Previous clinical data showed that gpE1/gpE2 can effectively induce cross-neutralizing antibodies, although they favor certain genotypes. HCV employs HVR1 within gpE2 to evade host immune control. It has been hypothesized that the removal of this domain would improve the production of cross-neutralizing antibodies. In this study, we compared the immunogenicities of WT and ΔHVR1 gpE1/gpE2 antigens as vaccine candidates. Our results indicate that the ΔHVR1 gpE1/gpE2 antigen confers no advantages in the neutralization of HCV compared with the WT antigen. Previously, we showed that this WT antigen remains the only vaccine candidate to protect chimpanzees from chronic infection, contains multiple cross-neutralizing epitopes, and is well tolerated and immunogenic in humans. The current data support the further clinical development of this vaccine antigen component.

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Antibody dynamics to SARS-CoV-2 in asymptomatic COVID-19 infections

10.1101/2020.07.09.20149633 ◽

2020 ◽

Cited By ~ 1

Author(s):

Qing Lei ◽

Yang Li ◽

Hongyan Hou ◽

Feng Wang ◽

Yandi Zhang ◽

...

Keyword(s):

Humoral Immunity ◽

Exposure Time ◽

Disease Transmission ◽

Neutralizing Antibodies ◽

Neutralizing Antibody ◽

Antibody Responses ◽

Pseudotyped Virus ◽

Serological Tests ◽

Asymptomatic Individuals ◽

Antibody Dynamics

Abstract Importance Asymptomatic COVID-19 infections have a long duration of viral shedding and contribute substantially to disease transmission. However, the missing asymptomatic cases have been significantly overlooked because of imperfect sensitivity of nucleic acid testing. We aimed to investigate the humoral immunity in asymptomatics, which will help us develop serological tests and improve early identification, understand the humoral immunity to COVID-19, and provide more rational control strategies for the pandemic. Objective To better control the pandemic of COVID-19, dynamics of IgM and IgG responses to 23 proteins of SARS-CoV-2 and neutralizing antibody in asymptomatic COVID-19 infections after exposure time were investigated. Design, setting, and participants 63 asymptomatic individuals were screened by RT-qPCR and ELISA for IgM and IgG from 11,776 personnel returning to work, and close contacts with the confirmed cases in different communities of Wuhan by investigation of clusters and tracing infectious sources. 63 healthy contacts with both negative results for NAT and antibodies were selected as negative controls. 51 mild patients without any preexisting conditions were also screened as controls from 1056 patients during hospitalization in Tongji Hospital. A total of 177 participants were enrolled in this study and serial serum samples (n=213) were collected. The research was conducted between 17 February 2020 and 28 April 2020. Serum IgM and IgG profiles of 177 participants were further probed using a SARS-CoV-2 proteome microarray. Neutralizing antibody responses in different population were detected by a pseudotyped virus neutralization assay system. The dynamics of IgM and IgG antibodies and neutralizing antibodies were analyzed with exposure time or symptoms onset. Results Asymptomatics were classified into four subgroups based on NAT and serological tests. In particular, only 19% had positive NAT results while approximately 81% detected positive IgM/IgG responses. Comparative SARS-CoV-2 proteome microarray further demonstrated that there was a significantly difference of antibody dynamics responding to S1 or N proteins among three populations, although IgM and IgG profiles could not be used to differentiate them. S1 specific IgM responses were elicited in asymptomatic individuals as early to the seventh day after exposure and peaked on days from 17d to 25d, which might be used as an early diagnostic biomarker and give an additional 36.5% seropositivity. Mild patients produced stronger both S1 specific IgM and neutralizing antibody responses than asymptomatic individuals. Most importantly, S1 specific IgM/IgG responses and the titers of neutralizing antibody in asymptomatic individuals gradually vanished in two months. Conclusions and relevance Our findings might have important implications for the definition of asymptomatic COVID-19 infections, diagnosis, serological survey, public health and immunization strategies.

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Longitudinal variation in SARS-CoV-2 antibody levels and emergence of viral variants: implications for the ability of serological assays to predict immunity.

10.1101/2021.07.02.21259939 ◽

2021 ◽

Author(s):

Frauke Muecksch ◽

Helen Wise ◽

Kate Templeton ◽

Becky Batchelor ◽

Maria Squires ◽

...

Keyword(s):

High Throughput ◽

Neutralizing Antibody ◽

Spike Protein ◽

Serological Tests ◽

Neutralization Activity ◽

Neutralizing Activity ◽

Quantitative Measurements ◽

Antibody Titers ◽

Antibody Levels ◽

Selection Of

Background Serological assays are being deployed to monitor antibody responses in SARS-CoV-2 convalescents and vaccine recipients. There is a need to determine whether such assays can predict immunity, as antibody levels wane and viral variants emerge. Methods We measured antibodies in a cohort of SARS-CoV-2 infected patients using several high-throughput serological tests and functional neutralization assays. The effects of time and spike protein sequence variation on the performance and predictive value of the various assays was assessed. Findings Neutralizing antibody titers decreased over the first few months post-infection but stabilized thereafter, at about 30% of the level observed shortly after infection. Serological assays commonly used to measure antibodies against SARS-CoV-2 displayed a range of sensitivities that declined to varying extents over time. Quantitative measurements generated by serological assays based on the spike protein were better at predicting neutralizing antibody titers than assays based on nucleocapsid, but performance was variable and manufacturer positivity thresholds were not able to predict the presence or absence of detectable neutralizing activity. Even though there was some deterioration in correlation between serological measurements and functional neutralization activity, some assays maintained an ability to predict neutralizing titers, even against variants of concern. Interpretation The ability of high throughput serological assays to predict neutralizing antibody titers is likely crucial for evaluation of immunity at the population scale. These data will facilitate the selection of the most suitable assays as surrogates of functional neutralizing activity and suggest that such measurements may have utility in clinical practice.

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Anti-SARS-CoV-2 Serology persistence over time in COVID-19 Convalescent Plasma Donors

10.1101/2021.03.08.21253093 ◽

2021 ◽

Author(s):

Valeria De Giorgi ◽

Kamille A West ◽

Amanda N Henning ◽

Leonard Chen ◽

Michael R Holbrook ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Natural Infection ◽

Initial Presentation ◽

Clinical Severity ◽

Final Visit ◽

Wide Range ◽

Antibody Levels ◽

Prospective Longitudinal ◽

Repeat Visits ◽

Over Time

ABSTRACTBackgroundCharacterizing the kinetics of the antibody response to SARS□CoV□2 is of critical importance to developing strategies that may mitigate the public health burden of COVID-19. We sought to determine how circulating antibody levels change over time following natural infection.Methods/MaterialsWe conducted a prospective, longitudinal analysis of COVID-19 convalescent plasma (CCP) donors at multiple time points over a 9-month period. At each study visit, subjects either donated plasma or only had study samples drawn. In all cases, anti-SARS-CoV-2 donor testing was performed using semi-quantitative chemiluminescent immunoassays (ChLIA) targeting subunit 1 (S1) of the SARS-CoV-2 spike (S) protein, and an in-house fluorescence reduction neutralization assay (FRNA).ResultsFrom April to November 2020 we enrolled 202 donors, mean age 47.3 ±14.7 years, 55% female, 75% Caucasian. Most donors reported a mild clinical course (91%, n=171) without hospitalization. One hundred and five (105) (52%) donors presented for repeat visits with a median 42 (12-163) days between visits. The final visit occurred at a median 160 (53-273) days post-symptom resolution. Total anti-SARS-CoV-2 antibodies (Ab), SARS-CoV-2 specific IgG and neutralizing antibodies were detected in 97.5%, 91.1%, and 74% of donors respectively at initial presentation. Neutralizing Ab titers based on FRNA50 were positively associated with mean IgG levels (p = <0.0001). Mean IgG levels and neutralizing titers were positively associated with COVID-19 severity, increased donor age and BMI (p=0.0006 and p=0.0028, p=0.0083 and p=0.0363, (p=0.0008 and p=0.0018, respectively). Over the course of repeat visits, IgG decreased in 74.1% of donors; FRNA50 decreased in 44.4% and remained unchanged in 33.3% of repeat donors. A weak negative correlation was observed between total Ab levels and number of days post-symptom recovery (r = 0.09).ConclusionAnti-SARS-CoV-2 antibodies were identified in 97% of convalescent donors at initial presentation. In a cohort that largely did not require hospitalization. IgG and neutralizing antibodies were positively correlated with age, BMI and clinical severity, and persisted for up to 9 months post-recovery from natural infection. On repeat presentation, IgG anti-SARS-CoV-2 levels decreased in 56% of repeat donors. Overall, these data suggest that CP donors possess a wide range of IgG and neutralizing antibody levels that are proportionally distributed across demographics, with the exception of age, BMI and clinical severity.

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Early detection of neutralizing antibodies against SARS-CoV-2 in COVID-19 patients in Thailand

PLoS ONE ◽

10.1371/journal.pone.0246864 ◽

2021 ◽

Vol 16 (2) ◽

pp. e0246864

Author(s):

Opass Putcharoen ◽

Supaporn Wacharapluesadee ◽

Wan Ni Chia ◽

Leilani Paitoonpong ◽

Chee Wah Tan ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Viral Infections ◽

Serological Test ◽

Neutralization Assay ◽

Igg Antibody ◽

Independent Manner ◽

Neutralization Activity ◽

Viral Neutralization ◽

Before And After ◽

Antibody Levels

Background The presence of neutralizing antibodies (NAbs) is an indicator of protective immunity for most viral infections. A newly developed surrogate viral neutralization assay (sVNT) offers the ability to detect total receptor binding domain-targeting NAbs in an isotype-independent manner, increasing the test sensitivity. Thus, specimens with low IgM/ IgG antibody levels showed strong neutralization activity in sVNT. Methods This study aimed to measure the %inhibition of NAbs measured by sVNT in PCR-confirmed COVID-19 patients. The sensitivity of sVNT for the diagnosis of SARS-CoV-2 infection and its kinetics were determined. Results Ninety-seven patients with PCR-confirmed SARS-CoV-2 infection were included in this study. Majority of the patients were 21–40 years old (67%) and 63% had mild symptoms. The sensitivity of sVNT for the diagnosis of SARS-CoV-2 infection was 99% (95% confidence interval (CI) 94.4–100%) and the specificity was 100% (95% CI 98.3–100%). The negative predictive value of sVNT from the samples collected before and after 7 days of symptom onset was 99.5% (95% CI 97.4–100%) and 100% (95% CI 93.8–100%), respectively. The level of inhibition at days 8–14 were significantly higher than days 0–7 (p<0.001). The median %inhibition values by severity of COVID-19 symptoms were 79.9% (interquartile range (IQR) 49.7–91.8%); 89.0% (IQR 71.2–92.4%); and 86.6% (IQR 69.5–92.8%), for mild, moderate and severe/critical symptoms respectively. The median level of sVNT %inhibition of severe was significantly higher than the mild group (p = 0.05). Conclusion The sVNT is a practical and robust serological test for SARS-CoV-2 infection and does not require specialized biosafety containment. It can be used clinically to aid diagnosis in both early and late infection especially in cases when the real-time RT-PCR results in weakly negative or weakly positive, and to determine the protective immune response from SARS-CoV-2 infection in patients.

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