scholarly journals SARS-CoV-2 Delta Variant Displays Moderate Resistance to Neutralizing Antibodies and Spike Protein Properties of Higher Soluble ACE2 Sensitivity, Enhanced Cleavage and Fusogenic Activity

Viruses ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2485
Author(s):  
Sabari Nath Neerukonda ◽  
Russell Vassell ◽  
Sabrina Lusvarghi ◽  
Richard Wang ◽  
Fernando Echegaray ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Neutralization Assay ◽  
Spike Protein ◽  
Therapeutic Antibodies ◽  
Partial Loss ◽  
Fusogenic Activity ◽  
Fold Reduction ◽  
Protein Properties ◽  
Moderate Resistance ◽  
Second Wave

The SARS-CoV-2 B.1.617 lineage variants, Kappa (B.1.617.1) and Delta (B.1.617.2, AY) emerged during the second wave of infections in India, but the Delta variants have become dominant worldwide and continue to evolve. Here, we compared B.1.617 variants for neutralization resistance by convalescent sera, mRNA vaccine-elicited sera, and therapeutic neutralizing antibodies using a pseudovirus neutralization assay. B.1.617.1, B.1.617.2, and AY.1 pseudoviruses showed a modest 1.5- to 4.4-fold reduction in neutralization by convalescent sera and vaccine-elicited sera. In comparison, similar modest reductions were also observed for C.37, P.1, R.1, and B.1.526 pseudoviruses, but 7- and 16-fold reductions for vaccine-elicited and convalescent sera, respectively, were seen for B.1.351 pseudoviruses. Among twenty-three therapeutic antibodies tested, four antibodies showed either complete or partial loss of neutralization against B.1.617.2 pseudoviruses and six antibodies showed either complete or partial loss of neutralization against B.1.617.1 and AY.1 pseudoviruses. Our results indicate that the current mRNA-based vaccines will likely remain effective in protecting against B.1.617 variants. Finally, the P681R substitution confers efficient cleavage of B.1.617 variants’ spike proteins and the spike of Delta variants exhibited greater sensitivity to soluble ACE2 neutralization, as well as fusogenic activity, which may contribute to enhanced spread of Delta variants.

scholarly journals SARS-COV-2 Delta variant displays moderate resistance to neutralizing antibodies and spike protein properties of higher soluble ACE2 sensitivity, enhanced cleavage and fusogenic activity

2021 ◽  
Author(s):  
Sabari Nath Neerukonda ◽  
Russell Vassell ◽  
Sabrina Lusvarghi ◽  
Richard Wang ◽  
Fernando Echegaray ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Neutralization Assay ◽  
Therapeutic Antibodies ◽  
Partial Loss ◽  
Neutralization Titer ◽  
Fusogenic Activity ◽  
Fold Reduction ◽  
Protein Properties ◽  
Moderate Resistance ◽  
Spike Proteins

The SARS-CoV-2 B.1.617 lineage variants, Kappa (B.1.617.1) and Delta (B.1.617.2, AY) emerged during the second wave of infections in India, but the Delta variants have become dominant worldwide and continue to evolve. The spike proteins of B.1.617.1, B.1.617.2, and AY.1 variants have several substitutions in the receptor binding domain (RBD), including L452R+E484Q, L452R+T478K, and K417N+L452R+T478K, respectively, that could potentially reduce effectiveness of therapeutic antibodies and current vaccines. Here we compared B.1.617 variants, and their single and double RBD substitutions for resistance to neutralization by convalescent sera, mRNA vaccine-elicited sera, and therapeutic neutralizing antibodies using a pseudovirus neutralization assay. Pseudoviruses with the B.1.617.1, B.1.617.2, and AY.1 spike showed a modest 1.5 to 4.4-fold reduction in neutralization titer by convalescent sera and vaccine-elicited sera. In comparison, similar modest reductions were also observed for pseudoviruses with C.37, P.1, R.1, and B.1.526 spikes, but seven- and sixteen-fold reduction for vaccine-elicited and convalescent sera, respectively, was seen for pseudoviruses with the B.1.351 spike. Four of twenty-three therapeutic neutralizing antibodies showed either complete or partial loss of neutralization against B.1.617.2 pseudoviruses due to the L452R substitution, whereas six of twenty-three therapeutic neutralizing antibodies showed either complete or partial loss of neutralization against B.1.617.1 pseudoviruses due to either the E484Q or L452R substitution. Against AY.1 pseudoviruses, the L452R and K417N substitutions accounted for the loss of neutralization by four antibodies and one antibody, respectively, whereas one antibody lost potency that could not be fully accounted for by a single RBD substitution. The modest resistance of B.1.617 variants to vaccine-elicited sera suggest that current mRNA-based vaccines will likely remain effective in protecting against B.1.617 variants, but the therapeutic antibodies need to be carefully selected based on their resistance profiles. Finally, the spike proteins of B.1.617 variants are more efficiently cleaved due to the P681R substitution, and the spike of Delta variants exhibited greater sensitivity to soluble ACE2 neutralization, as well as fusogenic activity, which may contribute to enhanced spread of Delta variants.

scholarly journals mRNA-1273 and BNT162b2 mRNA vaccines have reduced neutralizing activity against the SARS-CoV-2 Omicron variant

2021 ◽  
Author(s):  
Venkata-Viswanadh Edara ◽  
Kelly E Manning ◽  
Madison Ellis ◽  
Lilin Lai ◽  
Kathryn M Moore ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Neutralizing Antibodies ◽  
Neutralizing Antibody ◽  
Neutralization Assay ◽  
Antibody Responses ◽  
Spike Protein ◽  
Live Virus ◽  
Neutralizing Activity ◽  
Virus Neutralization Assay ◽  
Fold Reduction

The BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) vaccines generate potent neutralizing antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, the global emergence of SARS-CoV-2 variants with mutations in the spike protein, the principal antigenic target of these vaccines, has raised concerns over the neutralizing activity of vaccine-induced antibody responses. The Omicron variant, which emerged in November 2021, consists of over 30 mutations within the spike protein. Here, we used an authentic live virus neutralization assay to examine the neutralizing activity of the SARS-CoV-2 Omicron variant against mRNA vaccine-induced antibody responses. Following the 2nd dose, we observed a 30-fold reduction in neutralizing activity against the omicron variant. Through six months after the 2nd dose, none of the sera from naive vaccinated subjects showed neutralizing activity against the Omicron variant. In contrast, recovered vaccinated individuals showed a 22-fold reduction with more than half of the subjects retaining neutralizing antibody responses. Following a booster shot (3rd dose), we observed a 14-fold reduction in neutralizing activity against the omicron variant and over 90% of boosted subjects showed neutralizing activity against the omicron variant. These findings show that a 3rd dose is required to provide robust neutralizing antibody responses against the Omicron variant.

scholarly journals Neutralizing antibody and soluble ACE2 inhibition of a replication-competent VSV-SARS-CoV-2 and a clinical isolate of SARS-CoV-2

2020 ◽  
Author(s):  
James Brett Case ◽  
Paul W. Rothlauf ◽  
Rita E. Chen ◽  
Zhuoming Liu ◽  
Haiyan Zhao ◽  
...  
Keyword(s):  
Clinical Isolate ◽  
Neutralizing Antibodies ◽  
Neutralizing Antibody ◽  
Neutralization Assay ◽  
Spike Protein ◽  
Glycoprotein Gene ◽  
Level 3 ◽  
Focus Reduction ◽  
High Throughput Imaging ◽  
Biosafety Level

ABSTRACTAntibody-based interventions against SARS-CoV-2 could limit morbidity, mortality, and possibly disrupt epidemic transmission. An anticipated correlate of such countermeasures is the level of neutralizing antibodies against the SARS-CoV-2 spike protein, yet there is no consensus as to which assay should be used for such measurements. Using an infectious molecular clone of vesicular stomatitis virus (VSV) that expresses eGFP as a marker of infection, we replaced the glycoprotein gene (G) with the spike protein of SARS-CoV-2 (VSV-eGFP-SARS-CoV-2) and developed a high-throughput imaging-based neutralization assay at biosafety level 2. We also developed a focus reduction neutralization test with a clinical isolate of SARS-CoV-2 at biosafety level 3. We compared the neutralizing activities of monoclonal and polyclonal antibody preparations, as well as ACE2-Fc soluble decoy protein in both assays and find an exceptionally high degree of concordance. The two assays will help define correlates of protection for antibody-based countermeasures including therapeutic antibodies, immune γ-globulin or plasma preparations, and vaccines against SARS-CoV-2. Replication-competent VSV-eGFP-SARS-CoV-2 provides a rapid assay for testing inhibitors of SARS-CoV-2 mediated entry that can be performed in 7.5 hours under reduced biosafety containment.

scholarly journals 578. INO-4800 DNA Vaccine Induces Neutralizing Antibodies and T cell Activity Against Global SARS-CoV-2 Variants

2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S390-S391
Author(s):  
Viviane M Andrade ◽  
Aaron Christensen-Quick ◽  
Joseph Agnes ◽  
Jared Tur ◽  
Charles C Reed ◽  
...  
Keyword(s):  
T Cell ◽  
Immune Responses ◽  
Dna Vaccine ◽  
Stock Options ◽  
Neutralizing Antibodies ◽  
Cell Activity ◽  
Cellular Responses ◽  
Neutralization Assay ◽  
Material Support ◽  
Fold Reduction

Abstract Background Global surveillance has identified emerging SARS-CoV-2 variants of concern (VOC) associated with increased transmissibility, disease severity, and resistance to neutralization by current vaccines under emergency use authorization (EUA). Here we assessed cross-immune responses of INO-4800 vaccinated subjects against SARS-CoV-2 VOCs. Methods We used a SARS-CoV-2 IgG ELISA and a pseudo neutralization assay to assess humoral responses, and an IFNγ ELISpot to measure cellular responses against SARS-CoV-2 VOC in subjects immunized with the DNA vaccine, INO-4800. Results IgG binding titers were not impacted between wild-type (WT) and B.1.1.7 or B.1.351 variants. An average 1.9-fold reduction was observed for the P.1 variant in subjects tested at week 8 after receiving two doses of INO-4800 (Figure 1a). We performed a SARS-CoV-2 pseudovirus neutralization assay using sera collected from 13 subjects two weeks after administration of a third dose of either 0.5 mg, 1 mg, or 2 mg of INO-4800. Neutralization was detected against WT and the emerging variants in all samples tested. The mean ID50 titers for the WT, B.1.1.7, B.1.351 and P.1. were 643 (range: 70-729), 295 (range: 46-886), 105 (range: 25-309), and 664 (range: 25-2087), respectively. Compared to WT, there was a 2.1 and 6.9-fold reduction for B.1.1.7 and B.1.351, respectively, while there was no difference between WT and the P.1 variant (Figure 1b). Next, we compared cellular immune responses to WT and SARS-CoV-2 Spike variants elicited by INO-4800 vaccination. We observed similar cellular responses to WT (median = 82.2 IQR = 58.9-205.3), B.1.1.7 (79.4, IQR = 38.9- 179.7), B.1.351 (80, IQR = 40.0-208.6) and P.1 (78.3, IQR = 53.1-177.8) Spike peptides (Figure 2). Conclusion INO-4800 vaccination induced neutralizing antibodies against all variants tested, with reduced levels detected against B.1.351. IFNγ T cell responses were fully maintained against all variants tested. Disclosures Viviane M. Andrade, PhD, Inovio Pharmaceuticals Inc. (Employee) Aaron Christensen-Quick, PhD, Inovio Pharmaceuticals, Inc (Employee) Joseph Agnes, PhD, Inovio (Employee, Shareholder) Jared Tur, PhD, Inovio (Employee) Charles C. Reed, PhD, Inovio Pharmaceuticals (Employee, Shareholder) Richa Kalia, MS, Inovio Pharmaceuticals (Employee, Other Financial or Material Support, I have stock options with Inovio Pharmaceuticals as an employee.) Idania Marrero, MD, PhD, Inovio Pharmaceuticals (Employee, Shareholder) Dustin Elwood, PhD, Inovio Pharmaceuticals (Employee) Katherine Schultheis, MSc, Inovio Pharmaceuticals (Employee) Emma Reuschel, PhD, Inovio Pharmaceuticals (Employee) Trevor McMullan, MSc, Inovio (Shareholder) Patrick Pezzoli, BS, Inovio (Employee) Kimberly A. Kraynyak, PhD, Inovio Pharmaceuticals (Employee, Other Financial or Material Support, Stock options) Albert Sylvester, MS, Inovio (Employee, Shareholder) Mammen P. Mammen Jr., MD, Inovio Pharmaceuticals (Employee) J Joseph Kim, PhD, Inovio (Employee) David Weiner, PhD, Inovio (Board Member, Grant/Research Support, Shareholder, I serve on the SAB in addition to the above activities) Trevor R. F. Smith, PhD, Inovio (Employee, Shareholder) Stephanie Ramos, PhD, Inovio Pharmaceuticals (Employee) Laurent Humeau, PhD, Inovio Pharmaceuticals (Employee) Jean Boyer, PhD, Inovio (Employee) Kate Broderick, PhD, Inovio (Employee)

scholarly journals α-Hemolysin-Aided Oligomerization of the Spike Protein RBD Resulted in Improved Immunogenicity and Neutralization Against SARS-CoV-2 Variants

2021 ◽  
Vol 12 ◽  
Author(s):  
Jintao Zou ◽  
Haiming Jing ◽  
Xiaoli Zhang ◽  
Yiheng Liu ◽  
Zhuo Zhao ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Neutralization Assay ◽  
Spike Protein ◽  
Wild Type Virus ◽  
Carrier Protein ◽  
Specific Antibodies ◽  
Linear Epitopes ◽  
Cellular Immune ◽  
Candidate Antigen

The increase in confirmed COVID-19 cases and SARS-CoV-2 variants calls for the development of safe and broad cross-protective vaccines. The RBD of the spike protein was considered to be a safe and effective candidate antigen. However, the low immunogenicity limited its application in vaccine development. Herein, we designed and obtained an RBD heptamer (mHla-RBD) based on a carrier protein-aided assembly strategy. The molecular weight of mHla-RBD is up to 450 kDa, approximately 10 times higher than that of the RBD monomer. When formulated with alum adjuvant, mHla-RBD immunization significantly increased the immunogenicity of RBD, as indicated by increased titers of RBD-specific antibodies, neutralizing antibodies, Th2 cellular immune response, and pseudovirus neutralization activity, when compared to RBD monomer. Furthermore, we confirmed that RBD-specific antibodies predominantly target conformational epitopes, which was approximately 200 times that targeting linear epitopes. Finally, a pseudovirus neutralization assay revealed that neutralizing antibodies induced by mHla-RBD against different SARS-CoV-2 variants were comparable to those against the wild-type virus and showed broad-spectrum neutralizing activity toward different SARS-CoV-2 variants. Our results demonstrated that mHla-RBD is a promising candidate antigen for development of SARS-CoV-2 vaccines and the mHla could serve as a universal carrier protein for antigen design.

scholarly journals SARS-CoV-2 Omicron neutralization by therapeutic antibodies, convalescent sera, and post-mRNA vaccine booster

2021 ◽  
Author(s):  
Sabrina Lusvarghi ◽  
Simon D. Pollett ◽  
Sabari Nath Neerukonda ◽  
WEI WANG ◽  
Richard Wang ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Clinical Stage ◽  
Booster Vaccination ◽  
Neutralization Assay ◽  
Therapeutic Antibodies ◽  
Post Vaccination ◽  
Spike Gene ◽  
Rapid Spread ◽  
Vaccine Booster ◽  
High Level

The rapid spread of the highly contagious Omicron variant of SARS-CoV-2 along with its high number of mutations in the spike gene has raised alarm about the effectiveness of current medical countermeasures. To address this concern, we measured neutralizing antibodies against Omicron in three important settings: (1) post-vaccination sera after two and three immunizations with the Pfizer/BNT162b2 vaccine, (2) convalescent sera from unvaccinated individuals infected by different variants, and (3) clinical-stage therapeutic antibodies. Using a pseudovirus neutralization assay, we found that titers against Omicron were low or undetectable after two immunizations and in most convalescent sera. A booster vaccination significantly increased titers against Omicron to levels comparable to those seen against the ancestral (D614G) variant after two immunizations. Neither age nor sex were associated with differences in post-vaccination antibody responses. Only three of 24 therapeutic antibodies tested retained their full potency against Omicron and high-level resistance was seen against fifteen. These findings underscore the potential benefit of booster mRNA vaccines for protection against Omicron and the need for additional therapeutic antibodies that are more robust to highly mutated variants.

scholarly journals Sensitivity of infectious SARS-CoV-2 B.1.1.7 and B.1.351 variants to neutralizing antibodies

2021 ◽  
Author(s):  
Delphine Planas ◽  
Timothée Bruel ◽  
Ludivine Grzelak ◽  
Florence Guivel-Benhassine ◽  
Isabelle Staropoli ◽  
...  
Keyword(s):  
South Africa ◽  
Humoral Immunity ◽  
Partial Resistance ◽  
Neutralizing Antibodies ◽  
Natural Infection ◽  
Neutralization Assay ◽  
Fold Reduction ◽  
Nasal Swabs ◽  
Reference Virus ◽  
Antibody Levels

AbstractSARS-CoV-2 B.1.1.7 and B.1.351 variants emerged respectively in United Kingdom and South Africa and spread in many countries. Here, we isolated infectious B.1.1.7 and B.1.351 strains and examined their sensitivity to anti-SARS-CoV-2 antibodies present in sera and nasal swabs, in comparison with a D614G reference virus. We established a novel rapid neutralization assay, based on reporter cells that become GFP+ after overnight infection. B.1.1.7 was neutralized by 79/83 sera from convalescent patients collected up to 9 months post symptoms, almost similar to D614G. There was a mean 6-fold reduction in titers and even loss of activity against B.1.351 in 40% of convalescent sera after 9 months. Early sera from 19 vaccinated individuals were almost as potent against B.1.1.7 but less efficacious against B.1.351, when compared to D614G. Nasal swabs from vaccine recipients were not neutralizing, except in individuals who were diagnosed COVID-19+ before vaccination. Thus, faster-spreading variants acquired a partial resistance to humoral immunity generated by natural infection or vaccination, mostly visible in individuals with low antibody levels.

scholarly journals Antibody repertoire induced by SARS-CoV-2 spike protein immunogens

2020 ◽  
Author(s):  
Supriya Ravichandran ◽  
Elizabeth M. Coyle ◽  
Laura Klenow ◽  
Juanjie Tang ◽  
Gabrielle Grubbs ◽  
...  
Keyword(s):  
Antibody Response ◽  
Neutralizing Antibodies ◽  
Neutralization Assay ◽  
Spike Protein ◽  
Antibody Repertoire ◽  
Limited Information ◽  
Protein Antigens ◽  
Phage Display Libraries ◽  
Rational Vaccine Design ◽  
And Function

ABSTRACTMultiple vaccine candidates against SARS-CoV-2 based on viral spike protein are under development. However, there is limited information on the quality of antibody response generated following vaccination by these vaccine modalities. To better understand antibody response induced by spike protein-based vaccines, we immunized rabbits with various SARS-CoV-2 spike protein antigens: S-ectodomain (S1+S2) (aa 16-1213), which lacks the cytoplasmic and transmembrane domains (CT-TM), the S1 domain (aa 16-685), the receptor-binding domain (RBD) (aa 319-541), and the S2 domain (aa 686-1213 as control). Antibody response was analyzed by ELISA, Surface Plasmon Resonance (SPR) against different Spike proteins in native conformation, and a pseudovirion neutralization assay to measure the quality and function of the antibodies elicited by the different Spike antigens. All three antigens (S1+S2 ectodomain, S1 domain, and RBD) generated strong neutralizing antibodies against SARS-CoV-2. Vaccination induced antibody repertoire was analyzed by SARS-CoV-2 spike Genome Fragment Phage Display Libraries (SARS-CoV-2 GFPDL), which identified immunodominant epitopes in the S1, S1-RBD and S2 domains. Furthermore, these analyses demonstrated that surprisingly the RBD immunogen elicited a higher antibody titer with 5-fold higher affinity antibodies to native spike antigens compared with other spike antigens. These findings may help guide rational vaccine design and facilitate development and evaluation of effective therapeutics and vaccines against COVID-19 disease.One Sentence SummarySARS-CoV-2 Spike induced immune response

scholarly journals Early Antibody Responses Associated with Survival in COVID19 Patients

2021 ◽  
Author(s):  
Zhao-Hua Zhou ◽  
Sai Dharmarajan ◽  
Mari Lehtimaki ◽  
Susan L. Kirshner ◽  
Steven Kozlowski
Keyword(s):  
Clinical Trials ◽  
Early Detection ◽  
Neutralizing Antibodies ◽  
Advanced Disease ◽  
Antibody Responses ◽  
Spike Protein ◽  
Therapeutic Antibodies ◽  
Highly Sensitive ◽  
Antibody Levels ◽  
Over Time

AbstractNeutralizing antibodies to the SARS CoV-2 spike proteins have been issued Emergency Use Authorizations and are a likely mechanism of vaccines to prevent COVID-19. However, benefit of treatment with monoclonal antibodies has only been observed in clinical trials in outpatients with mild to moderate COVID-19 but not in patients who are hospitalized and/or have advanced disease. To address this observation, we evaluated the timing of anti SARS-CoV-2 antibody production in hospitalized patients with the use of a highly sensitive multiplexed bead-based immunoassay allowing for early detection of antibodies to SARS-CoV-2. We found that significantly lower levels of antibodies to the SARS-CoV-2 spike protein in the first week after symptom onset were associated with patients who expired as compared to patients who were discharged. We also developed a model, based on antibody level trajectory, to predict COVID 19 outcome that is compatible with greater antibody benefit earlier in COVID 19 disease.Author SummaryWe evaluated antibodies to SARS-CoV-2 over time in patients that were hospitalized with COVID 19. Early detection of Anti-SARS-CoV-2 antibodies was associated with survival in patients hospitalized with COVID 19. Early antibody levels predicted outcome in our study. This result is consistent with the benefit of therapeutic antibodies early in the course of COVID 19 disease. With additional study, early antibody levels may be helpful in deciding on appropriate therapies.

scholarly journals Infectivity and immune escape of the new SARS-CoV-2 variant of interest Lambda

2021 ◽  
Author(s):  
M&oacutenica L. Acevedo ◽  
Luis Alonso-Palomares ◽  
Andr&eacutes Bustamante ◽  
Aldo Gaggero ◽  
Fabio Paredes ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Immune Escape ◽  
Neutralization Assay ◽  
Spike Protein ◽  
Pseudotyped Virus ◽  
South American ◽  
Virus Neutralization Assay ◽  
Alpha Variant ◽  
Vaccination Campaigns ◽  
The Impact

Background: The newly described SARS-CoV-2 lineage C.37 was recently classified as a variant of interest by the WHO (Lambda variant) based on its high circulation rates in South American countries and the presence of critical mutations in the spike protein. The impact of such mutations in infectivity and immune escape from neutralizing antibodies are entirely unknown. Methods: We performed a pseudotyped virus neutralization assay and determined the impact of the Lambda variant on infectivity and immune escape using plasma samples from healthcare workers (HCW) from two centers in Santiago, Chile who received the two-doses scheme of the inactivated virus vaccine CoronaVac. Results: We observed an increased infectivity mediated by the Lambda spike protein that was even higher than that of the D614G (lineage B) or the Alpha and Gamma variants. Compared to the Wild type (lineage A), neutralization was decreased by 3.05-fold for the Lambda variant while it was 2.33-fold for the Gamma variant and 2.03-fold for the Alpha variant. Conclusions: Our results indicate that mutations present in the spike protein of the Lambda variant of interest confer increased infectivity and immune escape from neutralizing antibodies elicited by CoronaVac. These data reinforce the idea that massive vaccination campaigns in countries with high SARS-CoV-2 circulation must be accompanied by strict genomic surveillance allowing the identification of new isolates carrying spike mutations and immunology studies aimed to determine the impact of these mutations in immune escape and vaccines breakthrough.

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