CN113683692A

CN113683692A - SARS-CoV-2N protein antibody and its application

Info

Publication number: CN113683692A
Application number: CN202110989683.8A
Authority: CN
Inventors: 李一荣; 康雅虹; 潘运宝; 钱纯亘; 汪大明
Original assignee: Shenzhen Yhlo Biotech Co Ltd
Current assignee: Shenzhen Yhlo Biotech Co Ltd
Priority date: 2021-08-26
Filing date: 2021-08-26
Publication date: 2021-11-23
Anticipated expiration: 2041-08-26
Also published as: CN113683692B; WO2023025278A1

Abstract

The invention relates to the technical field of immunoassay, in particular to a SARS-CoV-2N protein antibody and application thereof. The two antibodies provided by the invention have complementary epitopes, and can be matched with each other, so that the improvement on sensitivity is effectively provided, and the detection rate is improved; and can improve specificity and reduce false positive.

Description

SARS-CoV-2N protein antibody and its application

Technical Field

The invention relates to the technical field of immunoassay, in particular to a SARS-CoV-2N protein antibody and application thereof.

Background

Coronaviruses (CoVs; subfamily Coronaviridae, order Viridae) are a highly diverse, enveloped, positive-sense-strand, single-stranded RNA virus that causes respiratory, intestinal, hepatic, and nervous system diseases of varying severity in a variety of animals, including humans. Coronaviruses are divided into four genera: alpha coronavirus, beta coronavirus (beta CoV), gamma coronavirus, and delta coronavirus. In the last 12 years, two new types of beta-coronavirus have emerged, severe acute respiratory syndrome (SARS-CoV) and middle east respiratory syndrome (MERS-CoV), which cause severe human disease.

2019 novel coronavirus is named as '2019-nCoV' by the world health organization, and then named as 'Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)' by the International Committee for viral Classification. SARS-CoV-2 is a new strain of coronavirus that has not previously been found in humans. The homology of the two proteins reaches more than 80 percent with acute respiratory syndrome (SARS-CoV), wherein, the homology of structural protein Nucleocapsid protein of the two proteins is 94.1 percent, and the homology of Spike protein of the two proteins is 84.1 percent.

Antigen detection refers to the application of SARS-CoV-2 specific antibody to directly detect the structural protein on the pathogen in the sample, and the detection result can directly indicate whether the organism is infected by the pathogen, and has the advantages of simple operation, reporting time period, etc. SARS-CoV-2 structural Protein includes Spike Protein (Spike Protein, transmembrane Protein, homologous trimer structure, such as "corona" distributed on the surface of virus and is the core component for mediating virus infection of cell), nucleocapsid Protein (Nucleoprotein, is the most abundant component expressed in new coronavirus structural Protein), Envelope Protein (Envelope Protein) and Membrane Protein (Membrane Protein). Among them, spike protein and nucleocapsid protein are the two most commonly used antigen detection targets. The spike protein is related to the virus escape immune body and is easy to mutate, and the nucleocapsid protein (N protein) has strong conservation, high abundance and strong antigenicity, and the antigenic determinant is the main binding site of the specific antibody. The nucleocapsid protein (N protein) was therefore chosen as the target for antigen detection.

In view of the above, the present invention is particularly proposed.

Disclosure of Invention

The present invention relates to antibodies capable of specifically binding to a SARS-CoV-2N protein selected from a and/or b;

a) comprises a heavy chain complementary determining region H-CDR1, H-CDR2 and H-CDR3 of which the amino acid sequences are shown as SEQ ID NO. 1-3 in sequence, and a light chain complementary determining region L-CDR1, L-CDR2 and L-CDR3 of which the amino acid sequences are shown as SEQ ID NO. 4-6 in sequence;

b) comprises a heavy chain complementary determining region H-CDR1, H-CDR2 and H-CDR3 of which the amino acid sequences are shown as SEQ ID NO. 7-9 in sequence, and a light chain complementary determining region L-CDR1, L-CDR2 and L-CDR3 of which the amino acid sequences are shown as SEQ ID NO. 10-12 in sequence.

The invention also relates to nucleic acids encoding the antibodies as described above.

The invention also relates to a vector comprising a nucleic acid as described above.

The invention also relates to a host cell comprising a nucleic acid as described above or transformed with a vector as described above.

The invention also relates to a method of producing an antibody as described above, comprising:

culturing a host cell as described above under suitable culture conditions; and

the antibody thus produced is recovered from the culture medium or from the cultured host cells.

The invention also relates to a solid phase carrier, the surface of which is coated with the antibody, and the antibody has a and b.

The invention also relates to a kit comprising a solid support as described above.

The invention also relates to a reagent, a kit or a test strip, which comprises the antibody.

The invention has the beneficial effects that:

the two antibodies provided by the invention have complementary epitopes, and can be matched with each other, so that the improvement on sensitivity is effectively provided, and the detection rate is improved; and can improve specificity and reduce false positive.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a diagram showing the result of SDS-PAGE of the N protein antigen of the novel coronavirus in one embodiment of the present invention;

FIG. 2 is a diagram showing the result of SDS-PAGE of an antibody prepared in one example of the present invention;

FIG. 3 is a vector map of pFUSE-CHIg-mG1 in one embodiment of the present invention;

FIG. 4 is a vector map of pFUSE2-CLIg-mk in one embodiment of the present invention;

FIG. 5 is a vector map of pFUSE-CHIgM in one embodiment of the present invention;

FIG. 6 is a SDS-PAGE electrophoresis of IgG1 chimeric antibody prepared in one embodiment of the invention;

FIG. 7 is an SDS-PAGE electrophoresis of IgM chimeric antibodies according to one embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the invention, one or more examples of which are described below. Each example is provided by way of explanation, not limitation, of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment, can be used on another embodiment to yield a still further embodiment.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The present invention relates to an antibody capable of specifically binding to a SARS-CoV-2N protein selected from a and/or b;

The term "complementarity determining regions" or "CDRs" refers to the highly variable regions of the heavy and light chains of immunoglobulins, as defined by Kabat et al (Kabat et al, Sequences of proteins of immunological interest,5th Ed, "US Department of Health and Human Services, NIH,1991, and later versions). There are three heavy chain CDRs and three light chain CDRs. Herein, the terms "CDR" and "CDRs" are used to refer to a region comprising one or more, or even all, of the major amino acid residues that contribute to the binding affinity of an antibody to the antigen or epitope it recognizes, depending on the circumstances. In another embodiment, the CDR regions or CDRs refer to the highly variable regions of the heavy and light chains of an immunoglobulin as defined by IMGT.

The term "heavy chain" is understood herein to include full-length heavy chains comprising a variable region (VH) having an amino acid sequence determining antigen specificity and a constant region having three constant domains (CH1, CH2 and CH3) or four constant domains (CH1, CH2, CH3 and CH4), as well as fragments thereof. Likewise, the term "light chain" as used herein includes full-length light chains comprising a variable region (VL) having an amino acid sequence that determines antigen specificity, as well as constant regions (CL), and fragments thereof. In the present invention, the variable region is obtained by ligating FR1-CDR1-FR2-CDR2-FR3-CDR3-FR4 in the following order, unless otherwise specified.

The terms "specific binding," "selective binding," "selectively binds," and "specifically binds" refer to the binding of an antibody to an epitope on a predetermined antigen. Typically, the antibody is administered at a rate of about less than 10^-4M、10^-5M、10^-6M、10^-7M、10^-8M、10^-9M or 10^-10M or less affinity (KD) binding. Targeting is typically specific binding.

Variants of antibodies are also within the scope of the invention, e.g., sequences each having at least 70%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or greater than 99% identity to the respective CDR or FR, or variable region VL and/or VH, or the full length amino acid or nucleotide sequence of an antibody described herein. In some cases, a variant of an antibody comprises at least the 6 CDRs described above; in some cases, a variant of an antibody comprises at least one heavy chain and one light chain, while in other cases, the variant form contains two identical light chains and two identical heavy chains (or subparts thereof). In some cases, antibody variants are conservative modifications or conservative substitutions or substitutions of antibody sequences provided herein. "conservative modification" or "conservative substitution" refers to the replacement of an amino acid in a protein with another amino acid having similar characteristics (e.g., charge, side chain size, hydrophobicity/hydrophilicity, backbone conformation, and rigidity, etc.) so that changes can be made frequently without changing the biological activity of the protein. It is known to The person skilled in The art that, in general, a single amino acid substitution in a non-essential region of a polypeptide does not substantially alter The biological activity (see, for example, Watson et al (1987) Molecular Biology of The Gene, The Benjamin/Cummings pub. Co., p. 224, (4 th edition)). In addition, substitution of structurally or functionally similar amino acids is unlikely to abolish biological activity. One skilled in the art will be able to determine suitable variants of the antigen binding molecules as set forth herein using well known techniques. The term "identity" with respect to nucleotide and amino acid sequences indicates the degree of identity between two nucleic acids or two amino acid sequences when optimally aligned and compared with appropriate insertions or deletions.

In some embodiments, a and b are independently selected from the group consisting of mouse derived antibodies, human-mouse chimeric antibodies, and humanized antibodies.

The term "chimeric antibody" refers to an antibody obtained by fusing a variable region of a murine antibody to a constant region of a human antibody, and can reduce an immune response induced by the murine antibody. Establishing chimeric antibody, firstly establishing hybridoma secreting mouse-derived specific monoclonal antibody, then cloning variable region gene from mouse hybridoma cell, cloning constant region gene of human antibody according to the need, connecting mouse variable region gene and human constant region gene into chimeric gene, inserting into expression vector, and finally expressing chimeric antibody molecule in eukaryotic system or prokaryotic system.

The term "humanized antibody", also known as CDR-grafted antibody (CDR), refers to an antibody produced by grafting murine CDR sequences into a human antibody variable region framework, i.e., a different type of human germline antibody framework sequence. Can overcome the heterogenous reaction induced by the chimeric antibody carrying a large amount of murine protein components. Such framework sequences can be obtained from public DNA databases or published references that include germline antibody gene sequences. Germline DNA Sequences of genes such as the human heavy and light chain variable regions can be obtained from the "VBase" human germline sequence database (www.mrccpe.com.ac.uk/VBase) and found in Kabat, E.A. et al, 1991, Sequences of Proteins of Immunological Interest,5th edition. To avoid reduced immunogenicity and reduced activity, the human antibody variable region framework sequences may be minimally back-mutated or back-mutated to retain activity. To avoid reduced immunogenicity and resulting reduced activity, the human antibody variable regions may be subjected to minimal back mutations to maintain activity.

In some embodiments, the heavy chain variable region of a is as set forth in SEQ ID NO 13 and the light chain variable region is as set forth in SEQ ID NO 14.

In some embodiments, the heavy chain variable region of b is set forth in SEQ ID NO. 15 and the light chain variable region is set forth in SEQ ID NO. 16.

In some embodiments, a and b have constant regions.

In some embodiments, the heavy chain constant regions of a and b are each independently a constant region selected from any one of IgG1, IgG2, IgG3, IgG4, IgA, IgM, IgE, IgD.

In some embodiments, the constant region of a is IgG1 or IgM and the constant region of b is IgG1 or IgM.

In some embodiments, the constant region of a is IgG1 and the constant region of b is IgM.

In some embodiments, the constant region of a is IgM and the constant region of b is IgG 1.

In some embodiments, the constant region of a is IgM and the constant region of b is IgM.

In some embodiments, the constant region of a is IgG1 and the constant region of b is IgG 1.

In some embodiments, the constant region of at least one of a and b is an IgM.

In a most preferred embodiment, the constant region of a is IgM and the constant region of b is IgG 1.

By using the IgM chimeric antibody as a capture antibody, antigen binding sites are increased, and reaction sensitivity is improved.

In some embodiments, the species of the constant region is from a cow, horse, pig, sheep, rat, mouse, dog, cat, rabbit, camel, donkey, deer, mink, chicken, duck, goose, or human, preferably a human.

In some embodiments, the antibody may further comprise a secretory signal sequence.

The secretory signal sequence refers to a sequence that induces secretion of an expressed protein or peptide by being linked to an N-terminus of a coding sequence located outside a cell membrane or outside a cell, and may be a peptide sequence consisting of about 18 to 30 amino acids. All proteins that are transported to the outside of the cell membrane have different signal sequences, which are cleaved by signal peptidases on the cell membrane. In general, for foreign proteins that are not naturally expressed by the host cell, a secretory signal sequence, or a modified sequence, that secretes the protein into the periplasm of the cell or the culture medium may be used.

The invention also relates to an isolated nucleic acid encoding the bispecific antibody as described above.

The nucleic acid is typically RNA or DNA, and the nucleic acid molecule may be single-stranded or double-stranded, but is preferably double-stranded DNA. A nucleic acid is "operably linked" when it is placed into a functional relationship with another nucleic acid sequence. For example, a promoter or enhancer is operably linked to a coding sequence if it affects the transcription of the coding sequence. It is preferable to use DNA nucleic acid when it is ligated to a vector. In addition, the nucleic acid molecule may be codon optimized for different host cells.

The term "vector" refers to a nucleic acid delivery vehicle into which a polynucleotide can be inserted. When a vector is capable of expressing a protein encoded by an inserted polynucleotide, the vector is referred to as an expression vector. The vector may be introduced into a host cell by transformation, transduction, or transfection, and the genetic material elements carried thereby are expressed in the host cell. Vectors are well known to those skilled in the art and include, but are not limited to: a plasmid; phagemid; a cosmid; artificial chromosomes such as Yeast Artificial Chromosomes (YACs), Bacterial Artificial Chromosomes (BACs), or artificial chromosomes (PACs) derived from P1; bacteriophage such as lambda phage or M13 phage, animal virus, etc. Animal viruses that may be used as vectors include, but are not limited to, retroviruses (including lentiviruses), adenoviruses, adeno-associated viruses, herpes viruses (e.g., herpes simplex virus), poxviruses, baculoviruses, papilloma viruses, papilloma polyoma vacuolatum viruses (e.g., SV 40). In some embodiments, regulatory elements commonly used in genetic engineering, such as enhancers, promoters, Internal Ribosome Entry Sites (IRES), and other expression control elements (e.g., transcription termination signals, or polyadenylation signals and poly-U sequences, etc.) are included in the vectors of the present invention.

The invention also provides a host cell comprising a nucleic acid as described above or transformed with a vector as described above.

Suitable host cells or cell lines for expressing the antigen binding proteins of the invention include: mammalian cells such as NS0, Sp2/0, CHO, COS, HEK, fibroblasts, and myeloma cells. Human cells may be used, thus allowing the molecule to be modified with human glycosylation patterns. Alternatively, other eukaryotic cell lines may be employed. The selection of suitable mammalian host cells, as well as methods for transformation, culture, amplification, screening, and product production and purification, are known in the art.

It can be demonstrated that bacterial cells can be used as host cells. Various strains of E.coli for expression are well known host cells in the biotechnology arts. Various strains of Bacillus subtilis, Streptomyces, other Bacillus species, and the like can also be used in the method.

If desired, yeast cell strains known to those skilled in the art, as well as insect cells, such as Drosophila and Lepidoptera insect and viral expression systems, can also be used as host cells.

According to a further aspect of the invention, it also relates to a method for producing an antibody as described above, comprising:

culturing a host cell as described above under suitable culture conditions; and

The present invention also provides a solid carrier having a surface coated with the antibody as described above and having both a and b.

Exemplary solid supports include, but are not limited to, column matrix materials, culture plates, tubes (EP tubes), dishes, flasks, microtiter plates, multiwell plates, microplate wells, microspheres, heat-killed formalin- (or other chemical) -fixed prokaryotic or eukaryotic cells, microscope slides, microtubes, and/or microtubes,

A film or any other optically clear polymer, or a combination thereof. The solid support may be composed in whole or in part of plastic, cellulose derivatives, nitrocellulose, glass fiber, latex, or a combination thereof.

The term "solid support" means that the support material is predominantly non-liquid-robust, thereby allowing accurate and traceable localization of nucleic acids on the support material. The solid support can be selected from polystyrene, plastic, cellulose, polyacrylamide, polyethylene polypropylene, cross-linked dextran, glass, silicone rubber, agarose gel, etc. The solid phase carrier can be in the form of membrane, sheet, porous plate, microsphere, etc. The preferred solid support is an elisa plate. It may contain 16, 32, 48, 64, 96 or more holes. In the present invention, the term "microsphere" may be a sphere, a nearly sphere, a cube, a polyhedron or an irregular shape. The diameter of the microspheres is preferably 10nm to 1mm, for example 100nm, 500nm, 1 μm, 10 μm, 100 μm, 500 μm; preferably 400nm to 10 μm. The microspheres are preferably magnetic beads, and the magnetic material is contained in the composition.

In some embodiments, the kit further comprises a second antibody that specifically recognizes the SARS-CoV-2N protein and is capable of pairing with a and b.

Paired antibodies mean two or more antibodies that bind to the same antigen, are directly different in epitope from the antigen to which they bind, are spatially separated from each other by an acceptable steric hindrance, and specifically recognize and bind to the antigen, and when one of the paired antibodies is a polyclonal antibody, at least a portion of the antibodies in the polyclonal antibody specifically recognize and bind to the antigen.

In some embodiments, the second antibody is a polyclonal antibody.

In some embodiments, the second antibody is of a species origin that is non-human and that is different from the species origin of a and b.

In some embodiments, the kit further comprises a third antibody that specifically recognizes the Fc-fragment of the second antibody, the third antibody being conjugated to a detectable signal substance.

The invention also relates to a method for detecting SARS-CoV-2 virus, comprising:

SARS-CoV-2 antigen is detected using the polypeptide, kit or test strip as described above.

In some embodiments, the test sample for detection is selected from biological tissue or lavage, cells, body fluids thereof, further selected from blood, serum, plasma, anticoagulation, cell culture supernatant, saliva, semen, amniotic fluid, villi, tissue or tissue lysate, pharyngeal swab, nasal swab, conjunctival swab, stool specimen, stool, urine, bronchial lavage, alveolar lavage, sputum.

Embodiments of the present invention will be described in detail with reference to examples.

EXAMPLE 1 preparation of immunogen

The novel coronavirus N protein full-length gene sequence is constructed into a vector pET28a, and is subjected to BL21(DE3) recombinant expression and then is prepared by affinity chromatography and ion exchange chromatography to obtain the immunogen.

The amino acid sequence composition is as follows:

(1) novel full-length coronavirus N protein

MSDNGPQNQR NAPRITFGGP SDSTGSNQNG ERSGARSKQR RPQGLPNNTA SWFTALTQHG KEDLKFPRGQ GVPINTNSSP DDQIGYYRRA TRRIRGGDGK MKDLSPRWYF YYLGTGPEAG LPYGANKDGI IWVATEGALN TPKDHIGTRN PANNAAIVLQ LPQGTTLPKG FYAEGSRGGS QASSRSSSRS RNSSRNSTPG SSRGTSPARM AGNGGDAALA LLLLDRLNQL ESKMSGKGQQ QQGQTVTKKS AAEASKKPRQ KRTATKAYNV TQAFGRRGPE QTQGNFGDQE LIRQGTDYKH WPQIAQFAPS ASAFFGMSRI GMEVTPSGTW LTYTGAIKLD DKDPNFKDQV ILLNKHIDAY KTFPPTEPKK DKKKKADETQ ALPQRQKKQQ TVTLLPAADL DDFSKQLQQS MSSADSTQA

The SDS-PAGE result of the above antigen is shown in FIG. 1.

Example 2 murine monoclonal antibody screening against the N protein of the novel coronavirus

The prepared novel coronavirus N protein is used for full-length immunization of BalB/C mice with proper age, and mouse tail blood is detected by ELISA (enzyme-linked immunosorbent assay) by using each immunogen until the titer reaches 10⁴When the immunization is stopped, the spleen of the mouse is taken out, and the spleen is fused with mouse myeloma cells Sp2/0 after treatment, and then positive hybridoma cell strains are screened by a limiting dilution method. The activity of the obtained mouse monoclonal antibody and the new crown N protein is verified, on one hand, the reaction sensitivity of a single antigen and the N protein is verified, and on the other hand, the sensitivity of the two antibodies after being paired with the N protein is verified.

TABLE 1 monoclonal antibody cell supernatant Activity assay results

TABLE 2 monoclonal antibody pairing test (double antibody sandwich method)

Antibody pairing 1: antibody 1 (capture antibody) + antibody 2-HRP; antibody pairing 2: antibody 1 (capture antibody) + antibody 3-HRP; antibody pairing 3: antibody 2 (capture antibody) + antibody 1-HRP; antibody pairing 4: antibody 2 (capture antibody) + antibody 3-HRP; antibody pairing 5: antibody 3 (capture antibody) + antibody 1-HRP; antibody pairing 6: antibody 3 (capture antibody) + antibody 2-HRP.

The SDS-PAGE result of the above antibody is shown in FIG. 2.

Example 3 IgM and IgG subtype chimeric antibodies against the N protein of the novel coronavirus

Amplifying corresponding positive hybridoma cell strains, extracting mRNA, amplifying gene sequences of variable regions of the positive hybridoma cell strains by using an RT-PCR method, respectively constructing the positive hybridoma cell strains on IgG chimeric antibody heavy chain and light chain expression vectors pFUSE-CHIg-mG1 and pFUSE2-CLIg-mk (vector maps are respectively shown in figures 3 and 4) after sequencing confirmation by using a Sanger method, and respectively constructing the positive hybridoma cell strains on IgM chimeric antibody heavy chain and light chain expression vectors pFUSE-CHIgM and pFUSE2-CLIg-mk (vector maps are respectively shown in figures 5 and 4). Extracting endotoxin-removed plasmid, transiently transfecting 293 cells with light chain and heavy chain according to an appropriate ratio, collecting supernatant of cultured cells after about 48h, and respectively purifying by Protein A (IgG) and Protein L (IgM) affinity chromatography and ion exchange chromatography to obtain chimeric antibodies, which are labeled as N-Ab-G1 (antibody a with IgG1 constant region), N-Ab-G2 (antibody b with IgG1 constant region), N-Ab-M1 (antibody a with IgM constant region) and N-Ab-M2 (antibody b with IgM constant region). The SDS-PAGE electrophoresis of the prepared IgG1 chimeric antibody is shown in FIG. 6, and the SDS-PAGE electrophoresis of the IgM chimeric antibody is shown in FIG. 7.

Example 4 verification of the Activity of chimeric antibodies against the N protein of the novel coronavirus

N-Ab-G1, N-Ab-G2, N-Ab-M1 and N-Ab-M2 are coated on an enzyme label plate according to proper concentration, BSA blocks the enzyme label plate, reacts with N protein with different concentration, and then HRP labeled rabbit polyclonal antibody with proper concentration is added for developing color by using TMB.

Combining N-Ab-G1, N-Ab-G2, N-Ab-M1 and N-Ab-M2 in a ratio of 1:1 in pairs, coating the combination on an enzyme label plate according to the concentration of 2ug/ml, adding HRP-labeled rabbit polyclonal antibody with appropriate concentration after BSA (bovine serum albumin) blocking and reacting with N antigens with different concentrations, and developing by using TMB.

Combination 1: N-Ab-G1& N-Ab-G2;

and (3) combination 2: N-Ab-G1& N-Ab-M1;

and (3) combination: N-Ab-G1& N-Ab-M2;

and (4) combination: N-Ab-G2& N-Ab-M1;

and (3) combination 5: N-Ab-G2& N-Ab-M2;

and (4) combination 6: N-Ab-M1& N-Ab-M2.

From the above data, the affinities of combinations 2-6 are all significantly better than combination 1, with combination 4 having the highest affinity and combination 6 being IgM, although the antibody valence is higher, it may be less than combination 4 due to greater steric hindrance.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

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Ser Val Glu Ala Ser Asp Tyr Ala Val Tyr Cys Gln Gln Tyr Tyr Ser

85 90 95

Tyr Pro Pro Thr Phe Gly Gly Gly Thr Lys Leu Glu Ile Lys Arg Thr

100 105 110

Claims

1. An antibody capable of specifically binding to a SARS-CoV-2N protein selected from a and/or b;

2. The antibody of claim 1, a and b are independently selected from the group consisting of a mouse derived antibody, a human-mouse chimeric antibody, and a humanized antibody.

3. The antibody of claim 1, wherein the heavy chain variable region of a is represented by SEQ ID NO 13 and the light chain variable region is represented by SEQ ID NO 14;

and/or;

the heavy chain variable region of b is shown as SEQ ID NO. 15, and the light chain variable region is shown as SEQ ID NO. 16.

4. The antibody of any one of claims 1 to 3, a and b having constant regions.

5. The antibody of claim 4, wherein the constant region of a is IgG1 or IgM and the constant region of b is IgG1 or IgM.

6. A nucleic acid encoding the antibody of any one of claims 1 to 5.

7. A vector comprising the nucleic acid of claim 6.

8. A host cell comprising the nucleic acid of claim 6 or transformed with the vector of claim 7.

9. A method of producing the antibody of any one of claims 1 to 5, comprising:

culturing the host cell of claim 9 under suitable culture conditions; and

10. A solid carrier having the antibody according to claim 4 or 5 coated on the surface thereof, and having both a and b.

11. A kit comprising the solid support of claim 10.

12. The kit of claim 11, further comprising a second antibody that specifically recognizes SARS-CoV-2N protein and is capable of pairing with a and b.

13. The kit of claim 12, wherein the second antibody is a polyclonal antibody.

14. The kit of claim 13, wherein the second antibody is of a non-human species origin and is of a species different from that of a and b.

15. A kit according to any one of claims 12 to 14, further comprising a third antibody which specifically recognizes the Fc-fragment of the second antibody, the third antibody being conjugated to a detectable signal substance.

16. A reagent, kit or strip comprising the antibody of any one of claims 1 to 5.