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Your Position: Home > COVID-19 R&D > Identification and characterization of neutralizing antibodies against COVID-19
Identification and characterization of neutralizing antibodies against COVID-19
Release time: 2020-06-16 Source: ACROBiosystems Read: 1242

Just weeks after parts of the U.S. began reopening, the COVID-19 infections are on the upswing in several states. As the COVID-19 pandemic continues, researchers and manufacturers are moving potential therapeutics into clinical trials at a dizzying pace. During the past two weeks, Eli Lilly and Regeneron successively announced their clinical trials of therapeutic antibody against COVID-19.


The development cycle of therapeutic antibodies is relatively short. Thus, many experts believe the efforts of the companies developing antibody drugs are so vital. Compared to vaccines or antiviral drugs, the therapeutic antibody’s potential to both treat and protect against viral infections makes them very unique. With the advantage of high specificity and easy to scale up, the neutralizing antibody development is drawing as much attention around the world.


Since the very beginning of the pandemic, ACROBiosystems has been committed to developing SARS-CoV-2 related protein reagents and kit products to support the development of diagnostics, vaccines, and therapeutics. Meanwhile, ACROBiosystems is also actively involved in the identification and characterization of neutralizing antibodies against COVID-19. Collaborating with East China Normal University, the First Affiliated Hospital of Zhejiang University, School of Medicine, and SymRay Biopharma Inc., ACROBiosystems recently published an article “Cross-neutralization antibodies against SARS-CoV-2 and RBD mutations from convalescent patient antibody libraries”.


1. The binding affinity of plasma to SARS-CoV-2 RBD


We examined the binding ability of plasma from 18 recovered COVID-19 patients to SARS-CoV-2 RBD by enzyme-linked immunosorbent assay (ELISA). We found that most of these convalescent patients were able to produce high titer of SARS-CoV-2 RBD-specific antibodies when compared with healthy donors (Fig. 1).

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Fig. 1 The binding affinity of plasma from each patient to RBD by ELISA. (P1-18, Patients with COVID-19 recovered. HD87-90, healthy donors)


2. Generation of patient-derived antibody library


The PBMC from 18 different COVID-19 recovered patients were isolated to generate phage-displayed scFv libraries for panning the neutralizing antibodies. Affinity selection of the patient-derived antibody library was performed using solid-phase-bound RBD. After three rounds of panning, 456 positive clones were identified to bind with RBD specifically. 19 of them were selectively expressed for the following steps.

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Fig. 2 The flow chart of construction and panning of patient-derived scFv libraries.


3. Epitope binning assay


19 IgG can be divided into six different Bins using the Octet method. Among them, Bin1 and Bin2 are the groups with most clones, suggesting that these two epitopes on RBD are most important for recognition by the humoral immune system.

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Fig. 3 The 19 antibodies were divided into 6 bins by epitope binning assay.


4. Cross-neutralization against SARS-CoV-2 RBD mutations 


According to the in vitro binding assay, some IgG in Bin2 show superior bioactivity in the blockade of RBD binding to human ACE2 cells. We chose four antibodies from Bin2 to further characterize the neutralizing activity against SARS-CoV-2 RBD mutants. As you can see from the Fig. 4, HTS0483 can bind with all the RBD mutants and successfully inhibit the binding between ACE2 and all RBD mutants, indicating that HTS0483 can be potentially developed into the therapeutics for COVID-19.

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Fig. 4 Cross-neutralization against SARS-CoV-2 RBD mutations by different antibodies. (A) The binding affinity of 4 positive antibodies from Bin2 to different SARS-CoV-2 RBD mutations. (B) The blocking ability of 4 positive antibodies from Bin2 to different SARS-CoV-2 RBD mutations 


5. Antiviral properties of human antibodies


All four antibodies from Bin2 showed very good neutralizing activities in the antiviral studies. The IC50 is between 12.5nM to 50nM.

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Fig. 5 Antiviral properties of human IgG antibodies. The authentic infection of SARS-CoV-2 to Vero-E6 cells was neutralized by Anti-RBD antibodies.


ACROBiosystems has developed anti-SARS-CoV-2 S protein RBD neutralizing antibody and Nucleocapsid antibody. In addition, kit products for neutralizing antibody screening and antibody titer assay, and recombination proteins are provided to accelerate the anti-SARS-CoV-2 drugs and vaccines R&D.


RBD and N antibody
——Human antibodies isolated from the serum of recovered patients

> As a control to develop various assays

> Accelerating SARS-COV-2 diagnostic kits, therapeutics and vaccines R&D


Antibody
MoleculeCat. No.SpeciesProduct DescriptionOrder/Preorder
S protein RBDSAD-S35HumanAnti-SARS-CoV-2 neutralizing antibody, Human IgG1

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Nucleocapsid proteinNUN-S41HumanAnti-SARS-CoV-2 Nucleocapsid Antibody, Human IgG1

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Antibody titer assay solution

——Multiple antibody titer assay kits

> High throughput, high flexibility, high reproducibility, high sensitivity and high stability

> Various assay kits available for different application of antibody titer measurement


Kits  For research use only.
MoleculeCat. No.SpeciesProduct DescriptionOrder/Preorder
S1 proteinTAS-K001SARS-CoV-2Anti-SARS-CoV-2 Antibody IgG Titer Serologic Assay kit (Spike protein S1)

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S protein RBDTAS-K002SARS-CoV-2Anti-SARS-CoV-2 Antibody IgG Titer Serologic Assay kit (Spike protein RBD)

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TAS-K003SARS-CoV-2Anti-SARS-CoV-2 neutralizing antibody titer serologic assay kit

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Antibody screening solution

——Inhibitor screening kit/pre-coupled magnetic beads/pre-coated plates

> High throughput inhibitor screening kit can screen 96 or 480 candidate antibodies simultaneously

> Ready-to-use beads and plates can improve the efficiency of neutralizing antibody screening


Kits  For research use only.
MoleculeCat. No.SpeciesProduct DescriptionOrder/Preorder
S protein RBDEP-105SARS-CoV-2SARS-CoV-2 Inhibitor Screening Kit

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S1 proteinMBS-K001SARS-CoV-2SARS-CoV-2 Spike S1 protein-coupled magnetic beads

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S protein RBDMBS-K002SARS-CoV-2SARS-CoV-2 Spike protein RBD-coupled magnetic beads

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S1 proteinSP-12SARS-CoV-2SARS-CoV-2 Spike S1 protein-Coated Plates, Clear, 96-Well

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S protein RBDRP-13SARS-CoV-2SARS-CoV-2 Spike protein RBD-Coated Plates, Clear, 96-Well

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Relevant proteins


ACRO supplies several SARS-CoV-2 antigen proteins and their mutants to help the research on the binding and inhibition performance of the antibodies.


Proteins
MoleculeCat. No.SpeciesHostProduct DescriptionOrder/Preorder
ACE2AC2-H82E6HumanHEK293Biotinylated Human ACE2 / ACEH Protein, His,Avitag™ (MALS verified)

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AC2-H82F9HumanHEK293Biotinylated Human ACE2 / ACEH Protein, Fc,Avitag™

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AC2-H5257HumanHEK293Human ACE2 / ACEH Protein, Fc Tag (MALS verified)

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AC2-C52H7CynomolgusHEK293Cynomolgus ACE2 / ACEH Protein, His Tag

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AC2-H52H8HumanHEK293Human ACE2 / ACEH Protein, His Tag (MALS verified)

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AC2-R5246RatHEK293Rat ACE2 / ACEH Protein, His Tag (MALS verified)

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AC2-M5248MouseHEK293Mouse ACE2 / ACEH Protein, His Tag (MALS verified)

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AC2-P5248Paguma larvataHEK293Paguma larvata ACE2 / ACEH Protein, His Tag

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S proteinSPN-C52H4SARS-CoV-2HEK293SARS-CoV-2 (COVID-19)  S protein (R683A, R685A), His Tag

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SPN-C52H8SARS-CoV-2HEK293SARS-CoV-2 (COVID-19)  S protein (R683A, R685A) , His Tag, active trimer (MALS verified)

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SPN-S52H5SARSHEK293SARS S protein (R667A), His Tag

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S1 proteinS1N-C52H3SARS-CoV-2HEK293SARS-CoV-2 (COVID-19) S1 protein, His Tag

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S1N-C82E8SARS-CoV-2HEK293Biotinylated SARS-CoV-2 (COVID-19) S1 protein, His,Avitag™ (MALS verified)

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S1N-S52H5SARSHEK293SARS S1 protein, His Tag (MALS verified)

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S1N-C52H4SARS-CoV-2HEK293SARS-CoV-2 (COVID-19) S1 protein, His Tag (MALS verified)

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S1N-C5255SARS-CoV-2HEK293SARS-CoV-2 (COVID-19) S1 protein, Fc Tag

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S1N-C5257SARS-CoV-2HEK293SARS-CoV-2 (COVID-19) S1 protein, Mouse IgG2a Fc Tag

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S1N-C5256SARS-CoV-2HEK293SARS-CoV-2 (COVID-19) S1 protein (D614G), His Tag

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S protein RBDSPD-C82E9SARS-CoV-2HEK293Biotinylated SARS-CoV-2 (COVID-19) S protein RBD, His,Avitag™ (MALS verified)

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SPD-C5255SARS-CoV-2HEK293SARS-CoV-2 (COVID-19) S protein RBD, Fc Tag (MALS verified)

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SPD-S52H6SARSHEK293SARS S protein RBD, His Tag (MALS verified)

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SPD-C52H3SARS-CoV-2HEK293SARS-CoV-2 (COVID-19) S protein RBD, His Tag (MALS verified)

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SPD-C5259SARS-CoV-2HEK293SARS-CoV-2 (COVID-19) S protein RBD, Mouse IgG2a Fc Tag

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SPD-S52H4SARS-CoV-2HEK293SARS-CoV-2 (COVID-19) S protein RBD (V367F), His Tag

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SPD-S52H5SARS-CoV-2HEK293SARS-CoV-2 (COVID-19) S protein RBD (N354D), His Tag

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SPD-S52H7SARS-CoV-2HEK293SARS-CoV-2 (COVID-19) S protein RBD (W436R), His Tag

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SPD-S52H8SARS-CoV-2HEK293SARS-CoV-2 (COVID-19) S protein RBD (R408I), His Tag

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SPD-S52H3SARS-CoV-2HEK293SARS-CoV-2 (COVID-19) S protein RBD (N354D, D364Y), His Tag

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Nucleocapsid proteinNUN-C51H9SARS-CoV-2E.coliSARS-CoV-2 (COVID-19) Nucleocapsid protein, His Tag

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NUN-C5227SARS-CoV-2HEK293SARS-CoV-2 (COVID-19) Nucleocapsid protein, His Tag

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NUN-C81Q6SARS-CoV-2E.coliBiotinylated SARS-CoV-2 (COVID-19) Nucleocapsid protein, His,Avitag™

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Envelope proteinENN-C5128SARS-CoV-2E.coliSARS-CoV-2 (COVID-19) Envelope protein, His Tag

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Papain-like ProteasePAE-C5148SARS-CoV-2E.coliSARS-CoV-2 (COVID-19) Papain-like Protease Protein, His Tag

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NSP1NS1-C51H7SARS-CoV-2E.coliSARS-CoV-2 (COVID-19) NSP1 Protein, His Tag

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NSP7NS7-C51H6SARS-CoV-2E.coliSARS-CoV-2 (COVID-19) NSP7 Protein, His Tag

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NSP8NS8-C5149SARS-CoV-2E.coliSARS-CoV-2 (COVID-19) NSP8 Protein, His Tag

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NSP7 & NSP8NS8-C5125SARS-CoV-2E.coliSARS-CoV-2 (COVID-19) NSP7&NSP8 Protein, His Tag

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NSP16 & NSP10NS0-C51W3SARS-CoV-2E.coliSARS-CoV-2 (COVID-19) NSP16&NSP10 Heterodimer Protein, His Tag&Twin Strep Tag

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S1 proteinSIN-V52H3HCoV-NL63HEK293HCoV-NL63 S1 protein, His Tag

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SIN-V52H4HCoV-229EHEK293HCoV-229E S1 protein, His Tag

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SIN-V52H5HCoV-OC43HEK293HCoV-OC43 S1 protein, His Tag

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SIN-V52H6HCoV-HKU1(isolate N5)HEK293HCoV-HKU1(isolate N5) S1 protein, His Tag

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S1 protein CTDS1D-C52H3SARS-CoV-2HEK293SARS-CoV-2 (COVID-19) S1 protein CTD, His Tag

Preorder

Expected launch date: Jul. 6

S1 protein NTDS1D-C52H6SARS-CoV-2HEK293SARS-CoV-2 (COVID-19) S1 protein NTD, His Tag

Preorder

Expected launch date: Jul. 13

S protein RBDSPD-C52H4SARS-CoV-2HEK293SARS-CoV-2 (COVID-19) S protein RBD (G476S), His Tag

Preorder

Expected launch date: Jun. 18

SPD-C52H5SARS-CoV-2HEK293SARS-CoV-2 (COVID-19) S protein RBD (V483A), His Tag

Preorder

Expected launch date: Jun. 18

Reference:

1. Cross-neutralization antibodies against SARS-CoV-2 and RBD mutations from convalescent patient antibody libraries.  doi: https://doi.org/10.1101/2020.06.06.137513


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