CN113735970A

CN113735970A - Anti-neocoronavirus fully-humanized broad-spectrum neutralizing antibody and application thereof

Info

Publication number: CN113735970A
Application number: CN202111102536.0A
Authority: CN
Inventors: 陈薇; 于长明; 孙韩聪; 迟象阳; 张冠英; 张军; 李建民; 范鹏飞; 王步森; 宰晓东; 张哲�; 房婷; 付玲; 陈郑珊; 郝勐; 陈旖; 徐婧含
Original assignee: Academy of Military Medical Sciences AMMS of PLA
Current assignee: Academy of Military Medical Sciences AMMS of PLA
Priority date: 2021-09-20
Filing date: 2021-09-20
Publication date: 2021-12-03
Anticipated expiration: 2041-09-20
Also published as: CN113735970B

Abstract

The invention discloses a fully human monoclonal antibody ZWC6 for resisting SARS-CoV-2, which is obtained by screening through flow sorting-single cell PCR technology, has unique CDR partition, and the antigen recognition epitope is positioned in the RBD region of S1 protein. EC of the antibody against wild type of new coronavirus₅₀Is 0.266. mu.g/mL, neutralizes EC of Beta strain₅₀Is 0.115. mu.g/mL, neutralizes EC of Delta strain₅₀Is 0.115. mu.g/mL, showing that the monoclonal antibody disclosed by the invention is mainly used for the current monoclonal antibodyThe variant has broad-spectrum high-efficiency neutralizing activity. The monoclonal antibody disclosed by the invention also has the characteristics of high expression, full humanity and good stability, is suitable for industrial production, and has great clinical application value for responding to outbreak epidemic caused by the current variant strain and the possible variant strain in the future.

Description

Anti-neocoronavirus fully-humanized broad-spectrum neutralizing antibody and application thereof

Technical Field

The invention discloses an antibody, and belongs to the fields of microbiology and immunology.

Background

The causative agent of the new coronarism is a novel coronavirus-2 (SARS-CoV-2), SARS-CoV-2 belongs to the genus of β -coronavirus of the family Coronaviridae, and is a enveloped, single-stranded, positive-strand RNA virus with a genome length of about 30 kb. The first 2/3 of the genome is the nonstructural gene ORF1a/b, which encodes mainly the enzymes involved in viral replication (RNA-dependent RNA polymerase, RdRp), and the second 1/3 encodes, in turn, four structural proteins: spike protein (S), envelope protein (E), membrane protein (M) and nucleocapsid protein (N). The S protein contains a virus receptor binding region, can be combined with an angiotensin converting enzyme 2(ACE2) receptor on the surface of a human cell, mediates virus adsorption and entry into the cell, and is a key protein for the virus to invade host susceptible cells.

The virus generates continuous random mutations in the transmission process, wherein some mutations can enhance the binding capacity of the S protein to ACE2 receptor and accelerate the transmission of the virus in human, such as N501Y, E484K, P681R and the like. Therefore, some virus variant strains carrying key site mutations show stronger infection capacity or stronger immune escape capacity, so that the effectiveness of the existing public health intervention measures or vaccines is reduced, for example, Alpha strains (B.1.1.7), Beta strains (B.1.351), Gamma strains (P.1) and Delta strains (B.1.617.2) which are listed as 'variants of concern' (VOC) by the World Health Organization (WHO) and the like, and the emergence of the variant strains provides a new and serious challenge for epidemic situation prevention and control.

Monoclonal neutralizing antibodies targeting the viral surface spike protein (S protein) have become a potentially effective means of treating neocorolla pneumonia by binding to the new corolla virus, inhibiting the activity of the virus and protecting cells from invasion. Compared with small molecule drugs and plasma therapy, the monoclonal antibody has clear drug mechanism, high selectivity to target spots, strong specificity and small side effect. According to the website information of the chimesentibody, 25 monoclonal antibodies targeting S protein enter clinical research, and the monoclonal antibodies are effective to wild type novel coronavirus. Three S protein targeting mabs have been granted FDA emergency use, including the regenerant mabs REGN10933 and REGN10987 in combination, the gift products of LY-COV555 and LY-COV016, VIR-7831 from Vir. However, with the continued evolution and variation of SARS-CoV-2, most of the developed mabs lost neutralizing activity against one or more of the variant strains, among which LY-CoV555 and LY-CoV016 developed from now on, and REGN10933 developed from regenerants lost neutralizing activity against the Beta strain virus. In order to cope with the immune escape of the virus, broad-spectrum monoclonal antibodies with conservative neutralizing epitopes are developed, and the broad-spectrum neutralizing monoclonal antibodies or the composition of two high-efficiency neutralizing monoclonal antibodies are developed, so that the method has great clinical application value.

Currently, neutralizing mabs can be prepared by hybridoma technology, humanized transgenic mice, phage library screening, and single cell PCR technology. The single cell PCR technology has the advantages of full human source, good natural stability and the like, and is widely used for the research and development of new crown neutralizing antibodies. The principle of the single cell PCR technology is that a protective monoclonal antibody for resisting virus exists in a novel coronavirus infection restorer or a novel corona vaccine vaccinator, a gene for coding the antibody is positioned in a single lymphocyte of peripheral blood of a human body, and the gene can be 'fished' through flow cytometry sorting and the single cell PCR technology. Then the molecule can be prepared in vitro in large scale by means of genetic engineering.

The invention aims to obtain a monoclonal antibody with excellent broad-spectrum neutralization activity from peripheral blood of a recombinant novel coronavirus vaccine vaccinee by adopting a flow sorting-single cell PCR technology, and aims to provide a fully human monoclonal therapeutic antibody with a good protection effect on COVID-19 so as to correspond to a currently popular variant and a variant which possibly appears in the future.

Disclosure of Invention

Based on the aim, the invention screens a monoclonal antibody against SARS-CoV-2 by flow sorting-single cell PCR technology, the amino acid sequences of CDR1, CDR2 and CDR3 regions of the heavy chain variable region of the monoclonal antibody are respectively shown as the amino acid sequences of 26 th to 33 th, 51 th to 58 th and 97 th to 111 th positions of SEQ ID NO. 1; the amino acid sequences of the CDR1, CDR2 and CDR3 of the light chain variable region are shown as amino acid sequences at positions 27-32, 50-52 and 89-97 of SEQ ID NO. 5, respectively. The monoclonal antibody is designated "ZWC 6" in the present application.

In a preferred embodiment, the amino acid sequence of the heavy chain variable region of the antibody is shown in SEQ ID NO. 1, and the amino acid sequence of the light chain variable region is shown in SEQ ID NO. 5.

In a more preferred embodiment, the amino acid sequence of the heavy chain constant region of the monoclonal antibody is set forth in SEQ ID NO. 3 and the amino acid sequence of the light chain constant region is set forth in SEQ ID NO. 7.

Secondly, the invention also provides a polynucleotide for encoding the heavy chain and the light chain of the monoclonal antibody, wherein the polynucleotide sequence for encoding the heavy chain variable region of the monoclonal antibody is shown by SEQ ID NO. 2, and the polynucleotide sequence for encoding the light chain variable region of the monoclonal antibody is shown by SEQ ID NO. 6.

In a preferred embodiment, the polynucleotide sequence encoding the heavy chain constant region of the monoclonal antibody is represented by SEQ ID NO. 4 and the polynucleotide sequence encoding the light chain constant region of the monoclonal antibody is represented by SEQ ID NO. 8.

Third, the present invention also provides a functional element for expressing the above polynucleotides encoding the heavy and light chains of the monoclonal antibody, which can be a conventional expression vector.

In a preferred embodiment, the functional element is a linear expression cassette.

In another preferred embodiment, the functional element is a mammalian expression vector.

Fourth, the present invention also provides a host cell containing the above-described linear expression cassette.

In a preferred embodiment, the cell is an Expi293F cell.

In another preferred embodiment, the cell is CHO-K1 or CHO-S cell, and the invention can use CHO-K1 or CHO-S cell to construct stable transformation engineering cell strain for industrial production.

Finally, the invention also provides the application of the monoclonal antibody in preparing a COVID-19 therapeutic drug.

The monoclonal antibody provided by the invention is obtained by screening through a flow sorting-single cell PCR technology, has a unique CDR partition, and the antigen recognition epitope of the monoclonal antibody is positioned in an RBD region of S1 protein. The affinity of the antibody to SARS-CoV-2 wild type S-ECD is 1.492nM, and the antibody can be used for detecting the antibody against Alpha strain, Beta strain, Gamma strain,The affinities of Delta strain S-ECD were 0.938nM, 0.658nM, 1.204nM, 4.211nM, respectively. EC for New coronavirus wild type in pseudovirus neutralization experiments₅₀Is 6.4ng/mL, neutralizes EC of Alpha strain₅₀Is 3.803ng/mL, neutralizes EC of Beta strain₅₀Is 3.649ng/mL, neutralizes the EC of Gamma strain₅₀Is 3.529ng/mL, neutralizes EC of Delta strain₅₀It was 4.446 ng/mL. EC for New coronavirus wild type in Euvirus neutralization experiments₅₀Is 0.266. mu.g/mL, neutralizes EC of Beta strain₅₀Is 0.115. mu.g/mL, neutralizes EC of Delta strain₅₀It was 0.115. mu.g/mL. ZWC6 was shown to have broad-spectrum highly potent neutralizing activity against the current major variant. The monoclonal antibody disclosed by the invention has the characteristics of high expression, full humanity and good stability, is suitable for industrial production, and has great clinical application value for responding to outbreak epidemic caused by the current variant strain and the possible variant strain in the future.

Drawings

FIG. 1 is a diagram of single cell sorting by flow cytometry;

FIG. 2 is the identification map of capillary electrophoresis after nested PCR amplification of three chain genes H, K and lambda;

FIG. 3 is a diagram of the nucleic acid electrophoresis identification of the linear expression cassettes of the heavy and light chains of the monoclonal antibody;

FIG. 4 is a graph showing the results of a search for the sequence of the variable region of the monoclonal antibody;

FIG. 5 is a graph showing the binding activity of antibody expression supernatant to SARS-CoV-2;

FIG. 6 shows the SDS-PAGE detection profile of the purified monoclonal antibody by affinity chromatography;

FIG. 7 is a graph showing the binding activity of monoclonal antibody ZWC6 to S protein, S1 protein, RBD protein, NTD protein, S2 protein as a function of concentration by ELISA;

FIG. 8 ELISA detection of ZWC6 cross-binding activity;

FIG. 9, ZWC6 broad spectrum neutralizing activity against novel coronaviruses;

FIG. 10, ZWC6 EC for Euviruses on cell models₅₀Measuring a curve chart;

FIG. 11, ZWC6 graph showing binding kinetics for WT S-ECD protein;

FIG. 12, ZWC6 graph showing binding kinetics for Alpha strain S-ECD protein;

FIG. 13, a graph of the binding kinetics of ZWC6 with Beta strain S-ECD protein;

FIG. 14, ZWC6 graph showing the binding kinetics of Gamma strain S-ECD protein;

FIG. 15, ZWC6 graph showing the binding kinetics of Delta strain S-ECD proteins;

FIG. 16, ZWC6 is a graph showing the binding kinetics of WT RBD protein.

Detailed Description

The invention will be further described with reference to specific embodiments, and the advantages and features of the invention will become apparent as the description proceeds. These examples are only illustrative and do not limit the scope of protection defined by the claims of the present invention.

EXAMPLE 1 screening and preparation of human anti-SARS-CoV-2 monoclonal antibody

1. Collection of blood samples

After obtaining the informed consent, 20mL of blood samples were collected 14 days after the second immunization of the recombinant novel coronavirus vaccine immunized vaccinee for subsequent experiments.

2. Flow sorting memory B cells

The collected blood samples were used for PBMC isolation by Ficoll density gradient centrifugation as follows:

1) taking fresh anticoagulated whole blood, and performing EDTA anticoagulation.

2) And (3) adding a separation solution with the same volume as the blood sample into the centrifuge tube, flatly spreading the blood sample above the liquid level of the separation solution, and keeping the interface of the two liquid levels clear.

3) Balancing, room temperature, horizontal rotor 800g, acceleration and deceleration 3, and centrifuging for 30 min.

4) After centrifugation, the tube bottom is red blood cells, the middle layer is separation liquid, the uppermost layer is a plasma/tissue homogenate layer, and a thin and compact white membrane is arranged between the plasma layer and the separation liquid layer, namely: a layer of mononuclear cells (including lymphocytes and monocytes).

5) The white membrane layer was carefully pipetted into a new 50mL centrifuge tube, diluted 3-fold with PBS and mixed by inversion. At room temperature, the rotor was rotated horizontally at 600g, centrifuged for 10min, and the supernatant was discarded. The washing was repeated 2 times.

6) The lymphocytes were resuspended in PBS for use.

7) The cells used for sorting were counted and according to the recommended amounts in the following table, all antibodies and antigens except Anti-His tag and Anti-FLAG tag antibodies were added first, incubated at 4 ℃ for 1h, followed by PBS + 2% FBS washing twice, Anti-His tag and Anti-FLAG tag antibodies were added, PBS + 2% FBS was used to complement the reaction system, and incubated at 4 ℃ for 1 h.

TABLE 1 flow sorting of fluorescent antibodies/antigens

8) The washing was repeated 2-3 times with PBS containing 2% FBS, 1mL FPBS was resuspended, the cell pellet was removed with a 40 μm cell sieve, and stored at 4 ℃ in the dark for sorting.

9) Individual memory B cells specific for SARS-CoV-2S-ECD were sorted using a cell sorter (Beckman MofloXDP). The sorting strategy is as follows: CD3^-/CD19⁺/IgG⁺/CD27⁺/SARS-CoV-2 S-ECD⁺FIG. 1, with lymphocytes circled in FIG. 1-A, with adhesion-removed cells circled in FIG. 1-B, and with CD3 circled in FIG. 1-C^-/CD19⁺B cells of (2), IgG circled in FIG. 1-D⁺/CD27⁺Memory B cell of (2), SARS-CoV-2S-ECD is circled in FIG. 1-E⁺The memory B cell of (a). Individual memory B cells were directly sorted into 96-well plates, each well of which was pre-loaded with 20. mu.L of both dearsenic water and 20U of RNase inhibitor, and stored at-80 ℃.

As a result: sorting to obtain 456 SARS-CoV-2S-ECD⁺The memory B cell of (a).

3. Amplification of fully human monoclonal antibody variable region gene by single cell-PCR technology

1) Reverse transcription PCR

With reference to the description (QIAGEN, 210212), the procedure is briefly described as follows:

456 single cells were sorted by flow cytometry. All of the following specific primers for each subtype of heavy chain (heavy chain, H), Kappa light chain (Kappa chain, Kappa), and Lamda light chain (Lamda chain, lambda) were added simultaneously to each reaction system (see the primer sequences in Table 2). Primer:

H：5′L-VH 1、5′L-VH 3、5′L-VH 4/6，5′L-VH 5、HuIgG-const-anti、3′Cm CH1

κ：5′L Vκ1/2、5′L Vκ3、5′L Vκ4、3′Cκ543–566

λ：5′L Vλ1、5′L Vλ2、5′L Vλ3、5′L Vλ4/5、5′L Vλ6、5′L Vλ7、5′L Vλ8、3′Cλ

TABLE 2 reverse transcription PCR primers

The PCR reaction system comprises: 5 Xbuffer 6 u L, dNTP 1.2.2 u L, reverse transcriptase (Qiagen, 210212)1.2 u L, primers as above, template for single cell, water to make up to 30L.

The PCR reaction conditions are as follows: reverse transcription at 50 deg.C for 30min, pre-denaturation at 95 deg.C for 15min, followed by 95 deg.C for 40s, 55 deg.C for 30s, 72 deg.C for 1min, 40 cycles, and final extension at 72 deg.C for 10 min.

2) Nested PCR

Taking 1 μ L of the reverse transcription product as a template, performing nested PCR reaction to amplify the variable regions of H, kappa and lambda, wherein primers for amplifying the heavy chain variable region, the kappa light chain variable region and the lambda light chain variable region are shown in the following table 3.

TABLE 3 nested PCR primers

The PCR reaction system comprises: 10 Xbuffer 5 u L, 2.5mM dNTP 4 u L, DNA polymerase (all gold biotechnology limited, AP141)0.5 u L, primers, template for reverse transcription product 1 u L, water to make up to 50L. The PCR reaction conditions are as follows: pre-denaturation at 95 ℃ for 10min, followed by 95 ℃ for 30s, 57 ℃ for 30s, 72 ℃ for 45s, 40 cycles, and finally extension at 72 ℃ for 10 min.

3) Capillary electrophoresis

The nested PCR amplification products were subjected to capillary electrophoresis using QIAGEN DNA Fast Analysis card (Qiagen, 929008) and clones with successful amplification of both heavy and light chain genes in a single cell were considered as successfully paired clones. FIG. 2 is the identification map of capillary electrophoresis after nested PCR amplification of three chain genes of H, kappa and lambda.

4) Sequence analysis

Positive clones identified by PCR were subjected to DNA sequencing and analysis, and variable region search was performed by logging in to the IMGT website (http:// www.imgt.org/IMGT _ vquest/analysis), and was representative of antibody sequences, as expected. As a result of the search, FIG. 4-A shows that in the heavy chain variable region, the homology was 90.97% or more in the V region and 81.25% or more in the J region, and reading frame 2 was used for the D region. FIG. 4-B shows the results of a light chain search with a V region homology of up to 94.62% and a J region homology of up to 91.43%.

4. Linear expression cassette expression antibodies

Compared with the traditional expression vector construction method, the construction of the linear expression frame is quicker. The designed linear expression cassette contains all the elements for expressing monoclonal antibodies in mammalian cells, and the linear expression cassette sequentially contains a CMV promoter sequence (Genbank accession number: X03922.1), an antibody leader peptide coding sequence, an antibody variable region (obtained by amplification from a single cell), an antibody constant region (biosynthetic, heavy chain constant region sequence shown by SEQ ID NO:3, DNA coding sequence shown by SEQ ID NO:4, Kappa type light chain constant region sequence shown by SEQ ID NO:7, DNA coding sequence shown by SEQ ID NO:8, Lamda type light chain constant region sequence shown by SEQ ID NO:9, DNA coding sequence shown by SEQ ID NO:10, and poly-A tail (Genbank accession number: X03896.1) from the 5' end, and the linear form of DNA is transfected into cells for antibody expression.

The specific process is that each PCR fragment is connected and constructed by in vitro overlap extension PCR technology:

1) amplification of promoter-leader sequences

And (3) respectively amplifying promoter-leader sequence fragments of a heavy chain and a light chain by taking pMD-CMVH and pMD-CMVL as templates. The PCR reaction system for amplifying the heavy chain promoter-leader sequence fragment comprises: template plasmid pMD-CMVH 10ng, 10 Xbuffer 5. mu.L, 2.5mM dNTP 4. mu. L, DNA polymerase 0.5. mu.L, primer 5'-CMV-UP (matching CMV promoter upstream sequence) (5'-GATATACGCGTTGACATTGATTATTGAC-3'), primer 3' -leader-H (HR) (5'-ACACTGAACACCTTTTAAAATTAG-3', nucleotide sequence for fusion of heavy chain, signal peptide sequence:

5'-ATGAACTTCGGGCTCAGCTTGATTTTCCTTGTCCTAATTTTAAAA GGTGT C-3') encoding the amino acid sequence MNFGLSLIFLVLILKGV. The PCR reaction system for amplifying the light chain promoter-leader sequence fragment comprises: 10ng of template plasmid pMD-CMVL, 5 uL of 10 Xbuffer, 0.5 uL of 2.5mM dNTP 4 u L, DNA polymerase, 5'-CMV-UP primer (5'-GATATACGCGTTGACATTGATTATTGAC-3'), 3' -leader-L (HR) (5'-CCCACAGGTACCAGATACCCATAG-3') for fusion of the light chain, and the nucleotide sequence of the full-length signal peptide sequence is as follows:

5-ATGGATTCACAGGCCCAGGTTCTTATGTTACTGCTGCTATGGGTATC TGGTACCTGTGGG, the amino acid sequence is MDSQAQVLMLLLLWVSGTCG, the signal peptide sequence is derived from murine monoclonal antibody variable region), and the water content is 50 μ L.

And (3) PCR reaction conditions: pre-denaturation at 95 ℃ for 10min, followed by 95 ℃ for 30s, 60 ℃ for 30s, 72 ℃ for 1min, 30 cycles, and finally extension at 72 ℃ for 10 min.

2) Amplification of antibody constant region-poly A tail fragment

The H chain constant region-poly A tail segment PCR system comprises: the template plasmid pMD-TKH 10ng, 10 Xbuffer 5. mu.L, 2.5mM dNTP 4. mu. L, DNA polymerase 0.5. mu.L, primer 5'-CH (5'-ACCAAGGGCCCATCGGTCTTCCCC-3'), primer 3' -TK-POLY (A) (5'-AAGTGTAGCGGTCACGCTGCGCGTAACC-3'), water to 50. mu.L.

The kappa chain constant region-poly A tail fragment PCR system comprises: template plasmid pMD-TK 10ng, 10 Xbuffer 5. mu.L, 2.5mM dNTP 4. mu. L, DNA polymerase 0.5. mu.L, primer 5 '-Ck (5'-ACTGTGGCTGCACCATCTGTCTTC-3'), primer 3' -TK-POLY (A) (5'-AAGTGTAGCGGTCACGCTGCGCGTAACC-3'), water to 50. mu.L.

The lambda chain constant region-poly A tail segment PCR system comprises: template plasmid pMD-TK lambda 10ng, 10 Xbuffer 5. mu.L, 2.5mM dNTP 4. mu. L, DNA polymerase 0.5. mu.L, primer 5 '-Clambda (CTACGTCAGCCCAAGGCTGCCCCC), primer 3' -TK-POLY (A) (5'-AAGTGTAGCGGTCACGCTGCGCGTAACC-3'), water to 50. mu.L.

The PCR reaction conditions are as follows: pre-denaturation at 95 ℃ for 10min, followed by 95 ℃ for 30s, 60 ℃ for 30s, 72 ℃ for 2min, 30 cycles, and finally extension at 72 ℃ for 10 min.

3) Amplification of antibody variable regions

Taking 1. mu.L of the nested PCR product as a template, and amplifying the H chain, the kappa chain and the lambda chain of the antibody by using TransStart Taq DNA polymerase according to the product specification respectively by using corresponding mixed primers, wherein the corresponding primers are shown in the following table 4.

TABLE 4 PCR primers

The respective separate score line portions are for merging with the upstream segment and the score bold portions are for merging with the downstream segment.

The PCR reaction system comprises: 10 x buffer 5 u L, 2.5mM dNTP 4 u L, DNA polymerase (all gold biotechnology limited, AP141)0.5 u L, primers as above, template for nested PCR product 1 u L, water to 50L.

The PCR reaction conditions are as follows: pre-denaturation at 95 ℃ for 4min, followed by 95 ℃ for 30s, 57 ℃ for 30s, 72 ℃ for 45s, 40 cycles, and finally extension at 72 ℃ for 10 min.

4) Amplification of Linear expression cassettes for heavy and light chains, respectively

The PCR reaction system comprises:

template: 10ng of purified promoter-leader fragment, 10ng of heavy chain/light chain variable region fragment, 10ng of heavy chain/light chain constant region-poly A tail fragment, 5. mu.L of 10 Xbuffer, 0.5. mu.L of 12.5mM dNTP 4. mu. L, DNA polymerase (all-open gold Biotechnology Co., Ltd., AP151-13), 5'-CMV-UP primer (5'-GATATACGCGTTGACATTGATTATTGAC-3') and 3' -TK-POLY (A) (5'-AAGTGTAGCGGTCACGCTGCGCGTAACC-3', water to 50. mu.L.

The PCR reaction conditions are as follows: pre-denaturation at 95 ℃ for 10min, followed by 95 ℃ for 30s, 60 ℃ for 30s, 72 ℃ for 3min, 30 cycles, and finally extension at 72 ℃ for 10 min.

5) PCR product recovery, purification and quantification

The PCR reaction product was recovered directly with the recovery kit of OMEGA. DNA quantification: the PCR-recovered product was quantified using Nano (GE healthcare).

6) Cell inoculation: 293T cells at 2X 10⁵Perml in 96 well cell culture plates in 5% CO₂The cells were incubated at 37 ℃ overnight in an incubator.

7) Cell co-transfection: the next day, 20 μ L of serum-free Opti-MEM medium was added to each well of the 96-well plate, 0.1 μ g each of the successfully constructed heavy and light chain linear expression cassette PCR products was mixed, 0.4 μ L of Turbofect (Thermo Scientific, R0531) was added after mixing, and after incubation for 15-20min, the mixture was added dropwise to overnight-cultured 293T cell culture wells. In the presence of 5% CO₂The cells were cultured at 37 ℃ for 48 hours in the cell incubator, and then the cell culture supernatant was collected for use.

The result of the PCR fusion amplification nucleic acid electrophoresis detection of the linear expression frame is shown in FIG. 3,

lanes

1 and 2 in FIG. 3 are respectively the promoter-leader sequences of the heavy chain and the light chain, and the amplification fragment is about 750bp, which is in line with the expectation;

lanes

3, 4 and 5 are constant region-poly A tail fragments of H chain, kappa chain and lambda chain, respectively, and the amplified fragments are about 2000bp, 1350bp and 1350bp, respectively, which are in line with expectations;

lanes

6 and 7 are the heavy chain and light chain expression frames of ZWD12 which are successfully constructed, and the amplified fragments are about 3100bp and 2450bp respectively, which are in line with the expectation;

lanes

8 and 9 are the ZWC6 heavy chain and light chain expression cassettes constructed successfully, and the amplified fragments are 3100bp and 2450bp respectively, which are expected; lane M is the Trans5K DNA Marker with molecular weights of 5000, 3000, 2000, 1500, 1000, 750, 500, 250, and 100bp, respectively, from large to small.

ELISA screening for antibodies with binding Activity

1) Coating: one day before the experiment, a 96-well ELISA plate is used, recombinant SARS-CoV-2S-ECD antigen and goat anti-human IgG (H & L) antibody (Abcam, ab97221) are diluted to the concentration of 2 mu g/mL by using a coating solution, and the enzyme label plate is coated with 100 mu L of the recombinant SARS-CoV-2S-ECD antigen and goat anti-human IgG (H & L) antibody (Abcam, ab97221) at 4 ℃ overnight.

2) And (3) sealing: the day of the experiment was washed 3 times with a plate washer (BIO-TEK, 405_ LS), 100. mu.L of blocking solution was added to each well, and incubated at 37 ℃ for 1 hour.

3) Sample incubation: the plate was washed 3 times, 50. mu.L of the transfected cell culture supernatant and 50. mu.L of the dilution were added, and incubated at 37 ℃ for 1 hour.

4) And (3) secondary antibody incubation: the plate was washed 3 times, and an HPR-labeled secondary goat anti-human IgG antibody (Abcam, ab97225) was diluted at a ratio of 1:10000 with a diluent, 100. mu.L per well was added to the corresponding well of the ELISA plate, and incubated at 37 ℃ for 1 hour.

5) Color development: washing the plate for 3 times, adding 100 mu L of TMB single-component color development liquid into each hole, developing for 6min, keeping out of the sun at room temperature, and then adding 50 mu L of stop solution into each hole to stop the reaction.

6) Detecting OD value at the position of 450-630nm by using an enzyme-labeled instrument, and taking a hole without a sample to be detected as negative control, wherein OD is_450-630Wells more than 2.1 times greater than the negative control were positive. .

As a result: 42 monoclonal antibodies were expressed and the binding activity of SARS-CoV-2S-ECD was identified, and 21 monoclonal antibodies were able to specifically bind to SARS-CoV-2S-ECD (see FIG. 5).

6. Construction of expression vector and enzyme digestion identification

ZWC6 light and heavy chain recombinant expression plasmids are constructed for expression preparation of the monoclonal antibody.

1) Construction of pCDNA3.4-ZWC6-H expression plasmid:

amplifying a heavy chain by taking a linear expression frame as a template, cutting gel and recovering a heavy chain fragment with the size of 1.4kb, digesting an expression vector pCDNA3.4(ThermoFisher Scientific, A14697) by using EcoR I/BamH I and then recovering, connecting the heavy chain and the vector fragment by a homologous recombination (NEBuilder HiFi DNA Assembly Master Mix, E2621L) method, transforming TOP10, picking a clone and sequencing and identifying to construct an expression vector pCDNA3.4-ZWC6-H of a successful heavy chain.

2) pCDNA3.4-ZWC 6-kappa expression plasmid construction:

amplifying a light chain by taking a light chain expression frame as a template, recovering a light chain fragment of about 0.7kb by glue, connecting the light chain and the vector fragment by a homologous recombination method, transforming TOP10, selecting a clone, sequencing and identifying to construct an expression vector pCDNA3.4-ZWC 6-kappa of the successful light chain.

3) Transient expression and affinity chromatography purification of monoclonal antibody

Using Expi293 expression System, 15. mu.g of heavy chain and 15. mu.g of light chain were mixed and transfected into Expi293F cells, following the instructions (ThermoFisher Scientific, A14635), after 5-6 days the culture was harvested, after centrifugation approximately 30mL of supernatant was obtained, 5mL volume of pre-packed Protein A affinity column was used, before loading was equilibrated with 20mM PBS, after the conductivity indicated baseline, the sample was injected, after loading was complete, the column was washed with 20mM PBS until baseline was stable, the Protein of interest was eluted using 0.1M glycine buffer pH 3.0, and after OD was reached zero₂₈₀After near baseline, collection was stopped, the column was washed with at least 3 column volumes of 20mM PBS until baseline leveled off, and the column was washed with 20% ethanol. The SDS-PAGE detection result of the monoclonal antibody after affinity chromatography purification is shown in figure 6: lane 1 shows the result of the reduction electrophoresis of mAb ZWC6, lane 2 shows the result of the reduction electrophoresis of mAb ZWD12, the theoretical molecular weights of the heavy and light chains are 50kDa and 25kDa, respectively, and it is expected that lane M shows the molecular weight markers (molecular weights: 250, 130, 100, 70, 55, 55, 35, 25, 15, 10kDa from large to small).

Example 2 recognition epitope analysis of antibody ZWC6

1) Coating: one day before the experiment, a 96-well enzyme-linked plate is used, recombinant SARS-CoV-2S-ECD antigen, S1 antigen, RBD antigen and S2 antigen are diluted to the concentration of 2 mu g/mL by using a coating solution, an enzyme label plate is coated, each well is 100 mu L, and the enzyme-linked plate is coated overnight at 4 ℃.

3) Sample incubation: the plate was washed 3 times, 100. mu.L of diluent was added to each well except the first well, the antibody was diluted to 1. mu.g/mL in the first well, 4-fold gradient dilution, 100. mu.L/well, three duplicate wells per antibody were set, and incubated at 37 ℃ for 1 h.

6) Detecting OD value at the position of 450-630nm by using an enzyme-labeled instrument, and taking a hole without a sample to be detected as negative control, wherein OD is_450-630Wells more than 2.1 times greater than the negative control were positive.

As a result: ZWC6 were tested for binding activity to different epitopes, specifically as shown in FIG. 7, ZWC6 specifically bound to S-ECD, S1 and RBD proteins of SARS-CoV-2WT in a dose-response relationship, but not to NTD and S2 proteins. The results show that the epitope recognized by monoclonal antibody ZWC6 is located in the RBD region of S1 protein.

The sequence analysis of mab ZWC6 was as follows:

the amino acid sequence of the heavy chain variable region is shown as SEQ ID NO. 1, the amino acid sequences of the CDR1, CDR2 and CDR3 regions of the heavy chain variable region are respectively shown as the amino acid sequences of 26 th to 33 th, 51 th to 58 th and 97 th to 111 th positions of SEQ ID NO. 1, and the polynucleotide sequence for coding the heavy chain variable region is shown as SEQ ID NO. 2; the amino acid sequence of the light chain variable region is shown in SEQ ID NO. 5, the amino acid sequences of the CDR1, CDR2 and CDR3 regions of the light chain variable region are shown in amino acid sequences 27-32, 50-52 and 89-97 of SEQ ID NO. 5 respectively, and the polynucleotide sequence encoding the light chain variable region is shown in SEQ ID NO. 6.

Example 3: cross-binding Activity identification of antibody ZWC6

ZWC6 was identified as having cross-binding activity with S protein of a variant of SARS-CoV-2 of interest (Variants of conccern), as described above, and the results are shown in FIG. 8. ZWC6 are combined with S-ECD protein of Alpha strain, Beta strain, Gamma strain and Delta strain specifically and show dose response relation. The results show that the monoclonal antibody ZWC6 can be cross-bound with S-ECD proteins of Alpha strain, Beta strain, Gamma strain and Delta strain.

Example 4 identification of pseudoviral neutralizing Activity of antibody ZWC6

1) Serially diluting the purified monoclonal antibody by 3 times from an initial concentration (ZWC6 monoclonal antibody initial concentration is 3.7 mu g/ml) of a culture medium DMEM + 10% FBS, adding the diluted monoclonal antibody into a 96-well culture plate, and setting 3 multiple wells with the volume of 50 mu L/well; then add each holeAdding 50 μ L pseudovirus suspension of wild type or mutant strain of new coronavirus (DMEM + 10% FBS diluted virus to appropriate titer), mixing well, adding survival control (without virus and antibody) and death control (with virus only), and standing at 37 deg.C with 5% CO₂The cell incubator was incubated for 1 h.

2) HEK293T cells were digested with 0.25% trypsin and then diluted to 2.5X 10 with medium (DMEM + 10% FBS)⁵cells/mL, seeded into 96-well cell culture plates in a volume of 100. mu.L/well, placed at 37 ℃ in 5% CO₂The cell culture box was cultured overnight.

3) After 48h, 100. mu.L of the cell culture supernatant was discarded, 100. mu.L of the chromogenic substrate was added, and the cells were incubated for 2min in the dark.

4) Absorbing 150 mu L of the solution, transferring the solution to a 96-hole white micropore plate, and reading a Luciferase signal value by using a Tecan Spark multifunctional micropore plate detector; cell viability was calculated using (Luc sample wells-Luc death control)/(Luc survival control-Luc death control), antibody EC was calculated using GraphPad Prism 8 to fit curves₅₀The value is obtained.

The results are shown in FIG. 9, EC of mAb ZWC6 disclosed in this invention against the wild-type pseudovirus of the novel coronavirus₅₀Is 6.4ng/mL, neutralizes EC of Alpha strain pseudovirus₅₀Is 3.803ng/mL, neutralizes EC of Beta strain pseudovirus₅₀Is 3.649ng/mL, neutralizes the EC of Gamma-pseudovirus strain₅₀Is 3.529ng/mL, neutralizes EC of Delta strain pseudovirus₅₀It was 4.446 ng/mL. The results show ZWC6 has broad-spectrum high-efficiency neutralizing activity against pseudoviruses of the current main variant strain.

Example 5 identification of the Euvirus neutralizing Activity of antibody ZWC6

1) Vero E6 cells were digested with 0.25% trypsin and then diluted to 3X 10 with medium (DMEM + 10% FBS)⁵cells/mL, seeded into 96-well cell culture plates in a volume of 100. mu.L/well, placed at 37 ℃ in 5% CO₂The cell culture box was cultured overnight.

2) On the day of the experiment, purified monoclonal antibody was diluted serially from the starting concentration (starting concentration of ZWC6 monoclonal antibody 100. mu.g/ml, 3-fold) in DMEM + 2% FBS medium, added to 96-well plates in a volume of 120. mu.L/well; mu.L of COVID-19 virus suspension (virus diluted with DMEM + 2% FBS, addition) was then added to each wellInto 100TCID₅₀And/well), mixing well, and placing in a cell culture box for incubation for 1 h.

3) Discarding cell culture supernatant in a 96-well plate, and adding 200 mu L of virus-antibody mixed suspension after co-incubation into each well; survival controls (no virus and antibody) and death controls (virus only) were also set and placed at 37 ℃ in 5% CO₂The cell culture box is used for culturing for 72 hours.

4) After 72h, the cell culture supernatant is discarded, 50 mu L of crystal violet staining solution is added for staining for 30min at room temperature, the staining solution is discarded, 200 mu L/hole pure water is added, and the washing is repeated for 6 times.

5) Discarding the washing solution, drying the plate with absorbent paper, adding 100 μ L decolorization solution, and dissolving to OD₆₂₀For reference, OD was measured with a microplate reader₅₇₀A value; cell viability was calculated using (OD sample wells-OD death control)/(OD survival control-OD death control), antibody EC was calculated using GraphPad Prism 8 to fit the curve₅₀The value is obtained.

The results are shown in FIG. 10, EC of mAb ZWC6 disclosed in this invention against the wild type of the novel coronavirus₅₀Is 0.266. mu.g/mL, neutralizes EC of Beta strain₅₀Is 0.115. mu.g/mL, neutralizes EC of Delta strain₅₀It was 0.115. mu.g/mL. It is demonstrated that ZWC6 has high neutralizing activity against the true virus of wild type, Beta and Delta variants of SARS-CoV-2.

Example 6 measurement of affinity of monoclonal antibody to S antigen by Surface Plasmon Resonance (SPR)

1) Preparing a buffer solution: 50mL of 10 XHBS-EP + buffer solution and 450mL of deionized water are weighed, mixed uniformly and put into a 500mL buffer solution bottle.

2) Protein liquid changing: using a desalting column to exchange the antibody and antigen protein into HBS-EP + buffer solution, placing the desalting column into an empty collecting tube, unscrewing the cover of the desalting column, centrifuging for 1min at 1500g to remove the original liquid in the column, adding 300 mu L of HBS-EP + buffer solution, centrifuging for 1min at 1500g, repeating for 4 times, placing the desalting column into a new collecting tube, adding 100 mu L of protein solution into the column, centrifuging for 2min at 1500g, collecting the filtered liquid, and using NanoVue to determine the protein concentration.

3) The Biocore T200 machine was turned on, the inlet tube A was inserted into the HBS-EP + buffer bottle, the ProteinA chip was placed in, and the Prime program was run.

4) Sample preparation: the ligand (antibody) was diluted to 0.5. mu.g/mL with HBS-EP + buffer, and the analyte (antigen) was diluted to 100nM, 50nM, 25nM, 12.5nM, 6.25nM, 3.125nM, 1.5625nM, 0.78125 nM.

5) Sample detection was performed using a multi-cycle detection method: opening Kinetics/Affinity in Run/Wizard, selecting 2-1 or 4-3 by Flow path, selecting Protein A by Chip type, selecting Ligand capture, and clicking the next step; filling HBS-EP + in Solution under Startup in a Setup interface, selecting 3 Number of cycles, and clicking the next step; at the Injection Parameters interface: filling in an antibody name by a Ligand name, wherein the Contact time is 60s, the Flow rate is 10 mu L/min, and the Stabilization period is 0 s; sample has a Contact time of 120s, a Flow rate of 30 μ L/min, and a Dissociation time of 900 s; in Regeneration, Solution is Glycine pH 1.5, Contact time is 30s, Flow rate is 30 mu L/min, and Stabilization period is 30 s; clicking the next step; fill in the Sample interface with analyte information: the molecular weight of the S-ECD is 134kDa, the molecular weight of the RBD is 26.5kDa, the concentrations are 0nM, 0.78125nM, 1.5625nM, 3.125nM, 6.25nM, 12.5nM, 25nM, 50nM, 100nM and 0.78125nM, 0.78125nM is selected as the repeat, and the next step is clicked; setting the analysis temperature and the temperature of the sample chamber to be 25 ℃ in a System preambles interface, and clicking the next step; selecting Sample and Reagent Rack1 in a Rack Position interface, setting a Sample Position, preparing and placing the Sample according to the Sample Position and the amount, and clicking the next step; and confirming that the volume of the running buffer solution reaches the volume required by the experiment, clicking Start, storing the experimental method and the result, starting the program to automatically run, and running for 5 hours.

6) And (4) analyzing results: opening data analysis Software Biacore T200 Evaluation Software, opening a running result file: clicking the Kinetics/Affinity to select the Surface bound; selecting 0nM and at least 5 appropriate concentrations in the Select cultures interface, and clicking the next step; clicking Kinetics in a Select Data interface; selecting 1:1Binding by a Method in a Fit Kinetics interface, and clicking Fit to perform data fitting; recording binding kinetics data ka, kd, K_DAnd the like. TABLE 5 monoclonal antibody ZWC6 is recorded based on Report displayed analytical dataBinding kinetics data ka, kd, K with different antigens_D. FIGS. 11-16 are graphs showing the determination of the affinity constants of ZWC6 for the S-ECD and WT RBD of WT, Alpha, Beta, Gamma, Delta strains, respectively, and K thereof_DSequentially at 1.492nM, 0.938nM, 0.658nM, 1.204nM, 4.211nM and 0.683 nM. The result shows that the neutralizing antibody has good affinity with the wild type of SARS-CoV-2 and the S antigen of the present main variant strain, and the neutralizing antibody can be developed into a special medicine for new coronary pneumonia.

TABLE 5 binding kinetics data of mAb ZWC6 to various antigens

Antigens	K_on(1/Ms)	K_off(1/s)	K_D(M)
				WT S-ECD	1.708*10^5	2.548*10^-4	1.492*10^-9
Alpha S-ECD	1.749*10^5	1.641*10^-4	9.384*10^-10
				Beta S-ECD	1.835*10^5	1.208*10^-4	6.583*10^-10
Gamma S-ECD	1.512*10^5	1.820*10^-4	1.204*10^-9
				Delta S-ECD	7.239*10^4	3.048*10^-4	4.211*10^-9
WT RBD	5.346*10^5	3.653*10^-4	6.832*10^-10

Sequence listing

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Ser Leu Arg Leu Ser Cys Ala Ala Ser Gly Phe Ser Phe Ser His Tyr

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Val Met Tyr Trp Val Arg Gln Ala Pro Gly Lys Gly Leu Asp Trp Val

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Ala Ile Ile Ser Phe Asp Gly Ser Ser Gln Tyr Tyr Ala Asp Ser Val

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Lys Gly Arg Phe Thr Ile Ser Arg Asp Asn Ser Lys Asp Thr Leu Tyr

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Leu Gln Met His Ser Leu Arg Pro Glu Asp Thr Ala Val Tyr Tyr Cys

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Ala Ile His Gly Gly Thr Tyr Tyr Tyr Asp Lys Asn Ile Leu Ala Trp

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Gly Gln Gly Thr Leu Val Thr Val Ser Ser

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gggacttatt actatgataa gaatattttg gcctggggcc agggaaccct ggtcaccgtc 360

tcctca 366

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Ser Thr Ser Gly Gly Thr Ala Ala Leu Gly Cys Leu Val Lys Asp Tyr

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Phe Pro Glu Pro Val Thr Val Ser Trp Asn Ser Gly Ala Leu Thr Ser

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Gly Val His Thr Phe Pro Ala Val Leu Gln Ser Ser Gly Leu Tyr Ser

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Leu Ser Ser Val Val Thr Val Pro Ser Ser Ser Leu Gly Thr Gln Thr

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Tyr Ile Cys Asn Val Asn His Lys Pro Ser Asn Thr Lys Val Asp Lys

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Lys Val Glu Pro Lys Ser Cys Asp Lys Thr His Thr Cys Pro Pro Cys

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Pro Ala Pro Glu Leu Leu Gly Gly Pro Ser Val Phe Leu Phe Pro Pro

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Lys Pro Lys Asp Thr Leu Met Ile Ser Arg Thr Pro Glu Val Thr Cys

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Val Val Val Asp Val Ser His Glu Asp Pro Glu Val Lys Phe Asn Trp

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Tyr Val Asp Gly Val Glu Val His Asn Ala Lys Thr Lys Pro Arg Glu

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Glu Gln Tyr Asn Ser Thr Tyr Arg Val Val Ser Val Leu Thr Val Leu

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His Gln Asp Trp Leu Asn Gly Lys Glu Tyr Lys Cys Lys Val Ser Asn

195 200 205

Lys Ala Leu Pro Ala Pro Ile Glu Lys Thr Ile Ser Lys Ala Lys Gly

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Gln Pro Arg Glu Pro Gln Val Tyr Thr Leu Pro Pro Ser Arg Asp Glu

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Pro Ser Asp Ile Ala Val Glu Trp Glu Ser Asn Gly Gln Pro Glu Asn

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305 310 315 320

Gln Lys Ser Leu Ser Leu Ser Pro Gly Lys

325 330

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gcgtcgacca agggcccatc ggtcttcccc ctggcaccct cctccaagag cacctctggg 60

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tggaactcag gcgccctgac cagcggcgtg cacaccttcc cggctgtcct acagtcctca 180

ggactctact ccctcagcag cgtggtgacc gtgccctcca gcagcttggg cacccagacc 240

tacatctgca acgtgaatca caagcccagc aacaccaagg tggacaagaa agttgagccc 300

aaatcttgtg acaaaactca cacatgccca ccgtgcccag cacctgaact cctgggggga 360

ccgtcagtct tcctcttccc cccaaaaccc aaggacaccc tcatgatctc ccggacccct 420

gaggtcacat gcgtggtggt ggacgtgagc cacgaagacc ctgaggtcaa gttcaactgg 480

tacgtggacg gcgtggaggt gcataatgcc aagacaaagc cgcgggagga gcagtacaac 540

agcacgtacc gtgtggtcag cgtcctcacc gtcctgcacc aggactggct gaatggcaag 600

gagtacaagt gcaaggtctc caacaaagcc ctcccagccc ccatcgagaa aaccatctcc 660

aaagccaaag ggcagccccg agaaccacag gtgtacaccc tgcccccatc ccgggatgag 720

ctgaccaaga accaggtcag cctgacctgc ctggtcaaag gcttctatcc cagcgacatc 780

gccgtggagt gggagagcaa tgggcagccg gagaacaact acaagaccac gcctcccgtg 840

ctggactccg acggctcctt cttcctctac agcaagctca ccgtggacaa gagcaggtgg 900

cagcagggga acgtcttctc atgctccgtg atgcatgagg ctctgcacaa ccactacaca 960

cagaagagcc tctccctgtc tccgggtaaa 990

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Ala Ile Arg Met Thr Gln Ser Pro Pro Thr Leu Ser Leu Ser Pro Gly

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Glu Arg Ala Thr Leu Ser Cys Arg Ala Ser Gln Ser Val Thr Asn Tyr

20 25 30

Leu Val Trp Tyr Gln Gln Lys Pro Gly Gln Ala Pro Arg Leu Leu Ile

35 40 45

Tyr Asp Thr Phe Asn Arg Ala Thr Gly Ile Pro Ala Arg Phe Ser Gly

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Ser Gly Ser Gly Thr Asp Phe Thr Leu Thr Ile Ser Ser Leu Glu Pro

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Glu Asp Phe Ala Val Tyr Tyr Cys Gln Gln Arg Ser Asn Trp Pro Pro

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Thr Phe Gly Gln Gly Thr Lys Val Asp Ile Lys Arg

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ggccaggctc ccaggctcct catctatgat acattcaaca gggccactgg catcccagcc 180

aggttcagtg gcagtgggtc tgggacagac ttcactctca ccatcagcag cctggagcct 240

gaagattttg cagtttatta ctgtcagcag cgtagcaact ggcctcccac ttttggccag 300

gggaccaaag tggatatcaa acgt 324

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Gly Asn Ser Gln Glu Ser Val Thr Glu Gln Asp Ser Lys Asp Ser Thr

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Tyr Ser Leu Ser Ser Thr Leu Thr Leu Ser Lys Ala Asp Tyr Glu Lys

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His Lys Val Tyr Ala Cys Glu Val Thr His Gln Gly Leu Ser Ser Pro

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Val Thr Lys Ser Phe Asn Arg Gly Glu Cys

100 105

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aaggtggata acgccctcca atcgggtaac tcccaggaga gtgtcacaga gcaggacagc 180

aaggacagca cctacagcct cagcagtacc ctgacgctga gcaaagcaga ctacgagaaa 240

cacaaagtct acgcctgcga agtcacccat cagggcctga gttcgcccgt cacaaagagc 300

ttcaacaggg gagagtgt 318

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Val Lys Ala Gly Val Glu Thr Thr Thr Pro Ser Lys Gln Ser Asn Asn

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Ser His Lys Ser Tyr Ser Cys Gln Val Thr His Glu Gly Ser Thr Val

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Glu Lys Thr Val Ala Pro Thr Glu Cys Ser

100 105

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cgtcagccca aggctgcccc ctcggtcact ctgttcccac cctcgagtga ggagcttcaa 60

gccaacaagg ccacactggt gtgtctcata agtgacttct acccgggagc cgtgacagtg 120

gcctggaagg cagatagcag ccccgtcaag gcgggagtgg agaccaccac accctccaaa 180

caaagcaaca acaagtacgc ggccagcagc tacctgagcc tgacgcctga gcagtggaag 240

tcccacaaaa gctacagctg ccaggtcacg catgaaggga gcaccgtgga gaagacagtg 300

gcccctacag aatgttca 318

Claims

1. A fully human monoclonal antibody against SARS-CoV-2, wherein the amino acid sequences of CDR1, CDR2 and CDR3 of the heavy chain variable region of the monoclonal antibody are shown as amino acid sequences at positions 26-33, 51-58 and 97-111 of SEQ ID NO. 1, respectively; the amino acid sequences of the CDR1, CDR2 and CDR3 of the light chain variable region are shown as amino acid sequences at positions 27-32, 50-52 and 89-97 of SEQ ID NO. 5, respectively.

2. The monoclonal antibody according to claim 1, wherein the heavy chain variable region of the monoclonal antibody has the amino acid sequence shown in SEQ ID NO. 1, and the light chain variable region has the amino acid sequence shown in SEQ ID NO. 5.

3. The monoclonal antibody of claim 2, wherein the amino acid sequence of the heavy chain constant region of the monoclonal antibody is set forth in SEQ ID NO. 3 and the amino acid sequence of the light chain constant region is set forth in SEQ ID NO. 7.

4. A polynucleotide encoding the heavy and light chains of the monoclonal antibody of any one of claims 1-3, wherein the polynucleotide sequence encoding the heavy chain variable region of the monoclonal antibody is represented by SEQ ID No. 2 and the polynucleotide sequence encoding the light chain variable region of the monoclonal antibody is represented by SEQ ID No. 6.

5. The polynucleotide of claim 4, wherein the polynucleotide sequence encoding the heavy chain constant region of the monoclonal antibody is represented by SEQ ID NO. 4 and the polynucleotide sequence encoding the light chain constant region of the monoclonal antibody is represented by SEQ ID NO. 8.

6. A functional element for expressing the polynucleotides encoding the heavy and light chains of the monoclonal antibody of claim 5, wherein the functional element is a linear expression cassette or a mammalian expression vector.

7. A host cell comprising the functional element of claim 6.

8. The host cell of claim 7, wherein the cell is an Expi293F cell.

9. The host cell of claim 7, wherein the cell is a CHO-K1 or CHO-S cell.

10. Use of a monoclonal antibody according to any one of claims 1 to 3 in the manufacture of a medicament for the treatment of COVID-19.