Neutralization of SARS-CoV-2 Omicron variant by sera from BNT162b2 or Coronavac vaccine recipients

Background The SARS-CoV-2 Omicron variant, designated as a Variant of Concern(VOC) by the World Health Organization, carries numerous spike protein mutations which have been found to evade neutralizing antibodies elicited by COVID-19 vaccines. The susceptibility of Omicron variant by vaccine-induced neutralizing antibodies are urgently needed for risk assessment. Methods Omicron variant strains HKU691 and HKU344-R346K were isolated from patients using TMPRSS2-overexpressing VeroE6 cells. Whole genome sequence was determined using nanopore sequencing. Neutralization susceptibility of ancestral lineage A virus and the Omicron, Delta and Beta variants to sera from 25 BNT162b2 and 25 Coronavac vaccine recipients was determined using a live virus microneutralization assay. Results The Omicron variant strain HKU344-R346K has an additional spike R346K mutation, which is present in 8.5% of strains in GISAID database. Only 20% and 24% of BNT162b2 recipients had detectable neutralizing antibody against the Omicron variant HKU691 and HKU344-R346K, respectively, while none of the Coronavac recipients had detectable neutralizing antibody titer against either Omicron isolates. For BNT162b2 recipients, the geometric mean neutralization antibody titers(GMT) of the Omicron variant isolates(5.43 and 6.42) were 35.7-39.9-fold lower than that of the ancestral virus(229.4), and the GMT of both omicron isolates were significantly lower than those of the beta and delta variants. There was no significant difference in the GMT between HKU691 and HKU344-R346K. Conclusions Omicron variant escapes neutralizing antibodies elicited by BNT162b2 or CoronaVac. The additional R346K mutation did not affect the neutralization susceptibility. Our data suggest that the Omicron variant may be associated with lower COVID-19 vaccine effectiveness.

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Antibody titers measured by commercial assays are correlated with neutralizing antibody titers calibrated by international standards

10.1101/2021.07.16.21260618 ◽

2021 ◽

Author(s):

Yu-An Kung ◽

Chung-Guei Huang ◽

Sheng-Yu Huang ◽

Kuan-Ting Liu ◽

Peng-Nien Huang ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Vaccine Development ◽

Geometric Mean ◽

Neutralizing Antibody ◽

Diagnostic Techniques ◽

International Standards ◽

World Health ◽

Serum Samples ◽

Antibody Titers ◽

Health Organization

The World Health Organization (WHO) has highlighted the importance of an international standard (IS) for SARS-CoV-2 neutralizing antibody titer detection, with the aim of calibrating different diagnostic techniques. In this study, IS was applied to calibrate neutralizing antibody titers (IU/mL) and binding antibody titers (BAU/mL) in response to SARS-CoV-2 vaccines. Serum samples were collected from participants receiving the Moderna (n = 20) and Pfizer (n = 20) vaccines at three time points: pre-vaccination, after one dose, and after two doses. We obtained geometric mean titers of 1404.16 and 928.75 IU/mL for neutralizing antibodies after two doses of the Moderna and Pfizer vaccines, respectively. These values provide an important baseline for vaccine development and the implementation of non-inferiority trials. We also compared three commercially available kits from Roche, Abbott, and MeDiPro for the detection of COVID-19 antibodies based on binding affinity to S1 and/or RBD. Our results demonstrated that antibody titers measured by commercial assays are highly correlated with neutralizing antibody titers calibrated by IS.

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Low neutralizing antibody titers against the Mu variant of SARS-CoV-2 in BNT162b2 vaccinated individuals

10.1101/2021.11.19.21266552 ◽

2021 ◽

Author(s):

Diego Alejandro Alvarez-Diaz ◽

Ana L Munoz ◽

Pilar Tavera-Rodriguez ◽

Maria T Herrera-Sepulveda ◽

Hector A Ruiz-Moreno ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Neutralizing Antibody ◽

Spike Protein ◽

World Health ◽

The World ◽

Need To Evaluate ◽

Surveillance Programs ◽

Antibody Titers ◽

Epidemiological Impact ◽

Health Organization

Background Global surveillance programs for the virus that causes COVID-19 are showing the emergence of variants with mutations in the Spike protein, including the Mu variant, recently declared as a Variant of Interest (VOI) by the World Health Organization. Because these types of variants can be more infectious or less susceptible to antiviral treatments and vaccine-induced antibodies. Objectives To evaluate the sensitivity of the Mu variant (B.1.621) to neutralizing antibodies induced by the BNT162b2 vaccine. Study design Three of the most predominant SARS-CoV-2 variants in Colombia during the epidemiological peaks of 2021 were isolated. Microneutralization assays were performed by incubating 120 TCDI50 of each SARS-CoV-2 isolate with five 2-fold serial dilutions of sera from 14 BNT162b2 vaccinated volunteers. The MN50 titer was calculated by the Reed-Muench formula Results The three isolated variants were Mu, a Variant of Interest (VOI), Gamma, a variant of concern (VOC), and B.1.111 that lacks genetic markers associated with greater virulence. At the end of August, the Mu and Gamma variants were widely distributed in Colombia. Mu was predominant (49%), followed by Gamma (25%). In contrast, B.1.111 became almost undetectable. The evaluation of neutralizing antibodies suggests that patients vaccinated with BNT162-2 generate neutralizing antibody titers against the Mu variant at significantly lower concentrations relative to B.1.111 and Gamma. Conclusions This study shows the importance of continuing with surveillance programs of emerging variants as well as the need to evaluate the neutralizing antibody response induced by other vaccines circulating in the country against Mu and other variants with high epidemiological impact.

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Prevalence and Persistence of Maternal Dengue Neutralizing Antibodies in Infants From Central and Southern Thailand: A Retrospective Cohort Study

Asia Pacific Journal of Public Health ◽

10.1177/1010539519853396 ◽

2019 ◽

Vol 31 (4) ◽

pp. 288-295 ◽

Cited By ~ 1

Author(s):

Adrienne Guignard ◽

François Haguinet ◽

Stéphanie Wéry ◽

Phirangkul Kerdpanich

Keyword(s):

Neutralizing Antibodies ◽

Vaccine Development ◽

Geometric Mean ◽

Neutralizing Antibody ◽

Maternal Antibodies ◽

Childhood Immunization ◽

Serum Samples ◽

Denv Serotypes ◽

Antibody Titers ◽

Antibody Kinetics

Understanding maternal dengue virus (DENV) neutralizing antibody kinetics in infants remains timely to develop a safe and effective childhood immunization. This retrospective study evaluated the prevalence and persistence of maternal antibody titers against DENV serotypes 1 to 4 in 139 Thai infants at 2, 6, and 7 months of age, using serum samples collected in a vaccination trial ( http://clinicaltrials.gov ; NCT00197275). Neutralizing antibodies against all 4 DENV serotypes were detected in 87.8% and 22.9% of infants at 2 and 7 months, respectively. At 2 months, DENV-4 neutralizing antibody geometric mean titers were notably lower (80) compared with DENV-1 to DENV-3 (277-471). Our results corroborate previous findings that DENV-1 to DENV-4 maternal antibodies persist at 7 months despite titers decrease from 2 months onwards. As persisting maternal antibodies may inhibit immune responses in DENV-vaccinated infants, a comprehensive understanding of DENV antibody kinetics is required in the perspective of vaccine development for infants.

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Incidence of Infection of Enterovirus 71 and Coxsackieviruses A6 and A16 among Household Contacts of Index Cases in Dong Thap Province, Southern Vietnam

BioMed Research International ◽

10.1155/2020/9850351 ◽

2020 ◽

Vol 2020 ◽

pp. 1-8

Author(s):

C. Q. Hoang ◽

H. D. Nguyen ◽

N. X. Ho ◽

T. H. T. Vu ◽

T. T. M. Pham ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Geometric Mean ◽

Age Groups ◽

Enterovirus 71 ◽

Foot And Mouth Disease ◽

Household Contacts ◽

Significant Difference ◽

Antibody Titers ◽

Index Cases

Background. Scarce information exists about immunity to hand, foot, and mouth disease (HFMD) among household contacts of index cases in Vietnam and what that means for reducing ongoing HFMD transmission in the community. Methods. We analyzed neutralizing antibodies (NT) and the incidence of enterovirus (EVs) infection among household contacts of index cases in a province where HFMD remains endemic. Throat swab and 2 mL blood samples from household contacts were collected at enrollment, during and after 2 weeks follow-up. Results. The incidence of EV-A71 infection among household contacts was 40/84 (47.6%, 95% Cl: 36.9-58.3%), compared with 106/336 (31.5%, 95% Cl: 26.6-36.5%) for CV-A6 and 36/107 (33.6%, 95% Cl: 24.7-42.6%) for CV-A16. The incidence of CV-A6 infection was fairly constant across ages; in contrast, CV-A71 and CV-A16 had some variation across ages. At baseline, higher geometric mean titer (GMT) of EV-A71, CV-A6, and CV-A16 antibody titers was found for 25-34-year groups (range 216.3 to 305.0) compared to the other age groups. There was a statistically significant difference in GMT values of CV-A6 and CV-A16 between those who had an infection or did not have infection among households with an index case of these serotypes. Conclusions. Our results indicated that adults were becoming infected with HFMD and could be contributing to the transmission. There is, therefore, a need for considering the household setting as an additional target for intervention programs for HFMD.

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Clinical utility of Elecsys Anti-SARS-CoV-2 S assay in COVID-19 vaccination: An exploratory analysis of the mRNA-1273 phase 1 trial

10.1101/2021.10.04.21264521 ◽

2021 ◽

Author(s):

Simon Jochum ◽

Imke Kirste ◽

Sayuri Hortsch ◽

Veit Peter Grunert ◽

Holly Legault ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Clinical Utility ◽

Dose Group ◽

Phase 1 ◽

Geometric Mean ◽

Neutralizing Antibody ◽

High Specificity ◽

Live Virus ◽

Phase 1 Trial ◽

Antibody Levels

Background The ability to quantify an immune response after vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is essential. This study assessed the clinical utility of the quantitative Roche Elecsys® Anti-SARS-CoV-2 S assay (ACOV2S) using samples from the 2019-nCoV vaccine (mRNA-1273) phase 1 trial (NCT04283461). Methods Samples from 30 healthy participants, aged 18-55 years, who received two injections with mRNA-1273 at a dose of 25 μg (n=15) or 100 μg (n=15), were collected at Days 1 (first vaccination), 15, 29 (second vaccination), 43 and 57. ACOV2S results (shown in U/mL - equivalent to BAU/mL per the first WHO international standard) were compared with results from ELISAs specific to antibodies against the Spike protein (S-2P) and the receptor binding domain (RBD) as well as neutralization tests including nanoluciferase (nLUC80), live-virus (PRNT80), and a pseudovirus neutralizing antibody assay (PsVNA50). Results RBD-specific antibodies were already detectable by ACOV2S at the first time point of assessment (d15 after first vaccination), with seroconversion before in all but 2 participants (25 μg dose group); all had seroconverted by Day 29. Across all post-baseline visits, geometric mean concentration of antibody levels were 3.27-7.48-fold higher in the 100 μg compared with the 25 μg dose group. ACOV2S measurements were highly correlated with those from RBD ELISA (Pearson's r=0.938; p<0.0001) and S-2P ELISA (r=0.918; p<0.0001). For both ELISAs, heterogeneous baseline results and smaller increases in antibody levels following the second vs first vaccination compared with ACOV2S were observed. ACOV2S showed absence of any baseline noise indicating high specificity detecting vaccine-induced antibody response. Moderate-strong correlations were observed between ACOV2S and neutralization tests (nLUC80 r=0.933; PsVNA50, r=0.771; PRNT80, r=0.672; all p≤0.0001). Conclusion The Elecsys Anti-SARS-CoV-2 S assay (ACOV2S) can be regarded as a highly valuable method to assess and quantify the presence of RBD-directed antibodies against SARS-CoV-2 following vaccination, and may indicate the presence of neutralizing antibodies. As a fully automated and standardized method, ACOV2S could qualify as the method of choice for consistent quantification of vaccine-induced humoral response.

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Serology in Children with Multisystem Inflammatory Syndrome (MIS-C) associated with COVID-19

10.1101/2020.07.10.20150755 ◽

2020 ◽

Cited By ~ 1

Author(s):

Christina A. Rostad ◽

Ann Chahroudi ◽

Grace Mantus ◽

Stacey A. Lapp ◽

Mehgan Teherani ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Limit Of Detection ◽

Geometric Mean ◽

Neutralization Assay ◽

Adverse Outcomes ◽

Igg Antibody ◽

Live Virus ◽

Lengths Of Stay ◽

Antibody Titers ◽

Inflammatory Syndrome

Objectives: We aimed to measure SARS-CoV-2 serologic responses in children hospitalized with multisystem inflammatory syndrome (MIS-C) compared to COVID-19, Kawasaki Disease (KD) and other hospitalized pediatric controls. Methods: From March 17, 2020 - May 26, 2020, we prospectively identified hospitalized children at Children's Healthcare of Atlanta with MIS-C (n=10), symptomatic PCR-confirmed COVID-19 (n=10), KD (n=5), and hospitalized controls (n=4). With IRB approval, we obtained prospective and residual blood samples from these children and measured SARS-CoV-2 spike (S) receptor binding domain (RBD) IgM and IgG binding antibodies by quantitative ELISA and SARS-CoV-2 neutralizing antibodies by live-virus focus reduction neutralization assay. We statistically compared the log-transformed antibody titers among groups and performed correlation analyses using linear regression. Results: All children with MIS-C had high titers of SARS-CoV-2 RBD IgG antibodies, which correlated strongly with neutralizing antibodies (R2=0.667, P<0.001). Children with MIS-C had significantly higher SARS-CoV-2 RBD IgG antibody titers (geometric mean titer [GMT] 6800, 95%CI 3495-13231) than children with COVID-19 (GMT 626, 95%CI 251-1563, P<0.001), children with KD (GMT 124, 95%CI 91-170, P<0.001) and other hospitalized pediatric controls (GMT 85 [all below assay limit of detection], P<0.001). All children with MIS-C also had detectable RBD IgM antibodies, indicating recent SARS-CoV-2 infection. RBD IgG titers correlated with erythrocyte sedimentation rate (ESR) (R2=0.512, P<0.046) and with hospital and ICU lengths of stay (R2=0.590, P=0.010). Conclusion: Quantitative SARS-CoV-2 RBD antibody titers may have a role in establishing the diagnosis of MIS-C, distinguishing it from other similar clinical entities, and stratifying risk for adverse outcomes.

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RESPIRATORY SYNCYTIAL VIRUS NEUTRALIZING ANTIBODIES IN PERSONS RESIDING IN CHICAGO, ILLINOIS

PEDIATRICS ◽

10.1542/peds.34.6.761 ◽

1964 ◽

Vol 34 (6) ◽

pp. 761-770

Author(s):

Marc Beem ◽

Rosalie Egerer ◽

Julia Anderson

Keyword(s):

Virus Infection ◽

Antibody Titer ◽

Neutralizing Antibodies ◽

Geometric Mean ◽

Indirect Evidence ◽

Neutralizing Antibody ◽

Single Strain ◽

Wild Strains ◽

Antibody Titers ◽

Syncytial Virus

The R.S. virus neutralization test was examined in terms of several factors bearing on the consistency and specificity of antibody response to a single strain (Randall) of this virus. It was found that this virus detected significant rises in antibody titer in 90% of 30 patients over 6 months of age who were infected with wild strains of R.S. virus between the years 1958 and 1962. Heterologous neutralizing antibodies to R.S. virus did not occur following human infections with various myxoviruses, adenoviruses, enteroviruses and herpesvirus. Indirect evidence was presented indicating that tile neutralizing activity of human serums is due to specific antibody and not due to non-specific, heat stable neutralizing substance. The titer of R.S. neutralizing antibodies was determined in the serums of 26 parturient mothers, and their 27 newborn babies, and 186 other individuals between the ages of 6 months and 69 years. Longitudinal observations of antibody titer were also conducted on 12 other infants. Neutralizing antibodies to R.S. virus were found to reach the term fetus at undiminished titer. In the longitudinal observations, serum neutralizing antibody titers were found to fall during the first months of life, decreasing by half in an average time of 43 days. Neutralizing antibodies, actively formed in response to R.S. virus infection, were observed to occur with rapidly increasing frequency in relation to age in subjects older than 6 months. These serologic findings indicated that among individuals residing in the metropolitan Chicago area, R.S. virus infection has been experienced by many during the first 2 years of life, most by school age, and all by 7 years of age. Geometric mean antibody titers were found to show a small, but probably significant, increase with age. The restriction of low titer reactors to pre-school children was noted. These serologic findings were interpreted as evidence that re-infections with R.S. virus occur, perhaps quite commonly.

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Antibody Response to the BNT162b2 mRNA COVID-19 Vaccine in Subjects with Prior SARS-CoV-2 Infection

Viruses ◽

10.3390/v13030422 ◽

2021 ◽

Vol 13 (3) ◽

pp. 422

Author(s):

Federico Gobbi ◽

Dora Buonfrate ◽

Lucia Moro ◽

Paola Rodari ◽

Chiara Piubelli ◽

...

Keyword(s):

Antibody Response ◽

Neutralizing Antibodies ◽

Natural Infection ◽

Vaccine Dose ◽

Neutralizing Antibody ◽

Immune Memory ◽

Effective Response ◽

Infected People ◽

Significant Difference ◽

Antibody Titers

Although antibody levels progressively decrease following SARS-CoV-2 infection, the immune memory persists for months. Thus, individuals who naturally contracted SARS-CoV-2 are expected to develop a more rapid and sustained response to COVID-19 vaccines than naïve individuals. In this study, we analyzed the dynamics of the antibody response to the BNT162b2 mRNA COVID-19 vaccine in six healthcare workers who contracted SARS-CoV-2 in March 2020, in comparison to nine control subjects without a previous infection. The vaccine was well tolerated by both groups, with no significant difference in the frequency of vaccine-associated side effects, with the exception of local pain, which was more common in previously infected subjects. Overall, the titers of neutralizing antibodies were markedly higher in response to the vaccine than after natural infection. In all subjects with pre-existing immunity, a rapid increase in anti-spike receptor-binding domain (RBD) IgG antibodies and neutralizing antibody titers was observed one week after the first dose, which seemed to act as a booster. Notably, in previously infected individuals, neutralizing antibody titers 7 days after the first vaccine dose were not significantly different from those observed in naïve subjects 7 days after the second vaccine dose. These results suggest that, in previously infected people, a single dose of the vaccine might be sufficient to induce an effective response.

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COVID-19 Repeated Convalescent Plasma Collection: Analysis of 149 Donations from 88 French Military Health Workers

Transfusion Medicine and Hemotherapy ◽

10.1159/000515843 ◽

2021 ◽

pp. 1-6

Author(s):

Pierre-Louis Conan ◽

Cécile Ficko ◽

Marine Chueca ◽

Carole Rolland ◽

Olivier Javaudin ◽

...

Keyword(s):

Antibody Titer ◽

Neutralizing Antibodies ◽

Health Workers ◽

Young Patients ◽

Neutralizing Antibody ◽

Military Health ◽

Service Workers ◽

The Third ◽

Significant Difference ◽

Antibody Titers

Background: Passive therapy with convalescent plasma (CP) could be an effective and safe treatment option in COVID-19 patients. Neutralizing antibodies present in CP generated in response to SARS-CoV-2 infection and directed against the receptor-binding domain of the spike protein are considered to play a major role in the viral clearance. CP infusion may also contribute to the modulation of the immune response through its immunomodulatory effect. We describe for the first time the effectiveness of a CP collection protocol from repeated donations in young patients. Materials and Methods: We enrolled health service workers who experienced mild to moderate COVID-19 and from whom several donations have been collected. No minimal severity threshold and no biological cure criteria were required. Donors could return to a second plasma donation 14 days after the first donation. A minimal neutralizing antibody titer of 1:40 was considered for clinical use. Results: Eighty-eight donors were included (median age 35 [28–48] years, 41 women), and 149 plasma products were collected. COVID-19 were mainly WHO stage 2 infections (96%). Among the 88 first donations, 76% had neutralizing antibody titers higher than or equal to 1:40. Eighty-eight percent of donors who came for a second donation had a neutralizing antibody titer of 1:40. Median durations were 15 (15–19) and 38 (33–46) days from the first to the second donation and from recovery to the second donation, respectively. Sixty-nine percent of donors who came for a third donation had a neutralizing antibody titer of 1:40. Median durations were 16 (13–37) and 54 (49–61) days from the second to the third donation and from recovery to the third donation, respectively. No significant difference was observed between the IgG ratio and the age of the donors or the time between recovery and donation. The average IgG ratio did not significantly vary between donations. When focused on repeated blood donors, no significant differences were observed either. Conclusion: The recruitment of young patients with a mild to moderate COVID-19 course is an efficient possibility to collect CP with a satisfactory level of neutralizing antibodies. Repeated donations are a well-tolerated and effective way of CP collection.

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Mutations that confer resistance to broadly-neutralizing antibodies define HIV-1 variants of transmitting mothers from that of non-transmitting mothers

10.1101/2021.01.07.21249396 ◽

2021 ◽

Author(s):

Amit Kumar ◽

Elena E Giorgi ◽

Joshua J Tu ◽

David R Martinez ◽

Joshua Eudailey ◽

...

Keyword(s):

Vertical Transmission ◽

Neutralizing Antibodies ◽

Neutralizing Antibody ◽

Maternal Plasma ◽

Pediatric Hiv ◽

World Health ◽

Autologous Plasma ◽

Maternal Risk ◽

Health Organization ◽

Hiv 1

Despite considerable reduction of mother-to-child transmission (MTCT) of HIV through use of maternal and infant antiretroviral therapy (ART), over 150,000 infants continue to become infected with HIV annually, falling far short of the World Health Organization goal of reaching <20,000 annual pediatric HIV cases worldwide by 2020. Prior to the widespread use of ART in the setting of pregnancy, over half of infants born to HIV-infected mothers were protected against HIV acquisition. Yet, the role of maternal immune factors in this protection against vertical transmission is still unclear, hampering the development of synergistic strategies to further reduce MTCT. It has been established that infant transmitted/founder (T/F) viruses are often resistant to maternal plasma, yet it is unknown if the neutralization resistance profile of circulating viruses predicts the maternal risk of transmission to her infant. In this study, we amplified HIV-1 envelope genes (env) by single genome amplification and produced representative Env variants from plasma of 19 non-transmitting mothers from the U.S. Women Infant Transmission Study (WITS), enrolled in the pre-ART era. Maternal HIV Env variants from non-transmitting mothers had similar sensitivity to autologous plasma as observed for non-transmitting variants from transmitting mothers. In contrast, infant variants were on average 30% less sensitive to paired plasma neutralization compared to non-transmitted maternal variants from both transmitting and non-transmitting mothers (p=0.015). Importantly, a signature sequence analysis revealed that motifs enriched in env sequences from transmitting mothers were associated with broadly neutralizing antibody (bnAb) resistance. Altogether, our findings suggest that circulating maternal virus resistance to bnAb-mediated neutralization, but not autologous plasma neutralization, near the time of delivery, predicts increased MTCT risk. These results caution that enhancement of maternal plasma neutralization through passive or active vaccination during pregnancy could drive the evolution of variants fit for vertical transmission.

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