WO2023179546A1 - 纳米抗体s43的构建体及其应用 - Google Patents

纳米抗体s43的构建体及其应用 Download PDF

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WO2023179546A1
WO2023179546A1 PCT/CN2023/082531 CN2023082531W WO2023179546A1 WO 2023179546 A1 WO2023179546 A1 WO 2023179546A1 CN 2023082531 W CN2023082531 W CN 2023082531W WO 2023179546 A1 WO2023179546 A1 WO 2023179546A1
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nanobody
cov
sars
seq
amino acid
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French (fr)
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王奇慧
高福
刘红辉
刘博�
仵丽丽
韩鹏程
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中国科学院微生物研究所
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K16/00—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies
    • C07K16/08—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from viruses
    • C07K16/10—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from viruses from RNA viruses
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
    • A61P31/00—Antiinfectives, i.e. antibiotics, antiseptics, chemotherapeutics
    • A61P31/12—Antivirals
    • A61P31/14—Antivirals for RNA viruses
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
    • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
    • G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
    • G01N33/569—Immunoassay; Biospecific binding assay; Materials therefor for microorganisms, e.g. protozoa, bacteria, viruses
    • G01N33/56983—Viruses
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K39/00—Medicinal preparations containing antigens or antibodies
    • A61K2039/505—Medicinal preparations containing antigens or antibodies comprising antibodies
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K39/00—Medicinal preparations containing antigens or antibodies
    • A61K2039/54—Medicinal preparations containing antigens or antibodies characterised by the route of administration
    • A61K2039/541—Mucosal route
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K39/00—Medicinal preparations containing antigens or antibodies
    • A61K2039/54—Medicinal preparations containing antigens or antibodies characterised by the route of administration
    • A61K2039/541—Mucosal route
    • A61K2039/542—Mucosal route oral/gastrointestinal
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K39/00—Medicinal preparations containing antigens or antibodies
    • A61K2039/54—Medicinal preparations containing antigens or antibodies characterised by the route of administration
    • A61K2039/541—Mucosal route
    • A61K2039/543—Mucosal route intranasal
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/30—Immunoglobulins specific features characterized by aspects of specificity or valency
    • C07K2317/31—Immunoglobulins specific features characterized by aspects of specificity or valency multispecific
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/50—Immunoglobulins specific features characterized by immunoglobulin fragments
    • C07K2317/56—Immunoglobulins specific features characterized by immunoglobulin fragments variable (Fv) region, i.e. VH and/or VL
    • C07K2317/565—Complementarity determining region [CDR]
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/50—Immunoglobulins specific features characterized by immunoglobulin fragments
    • C07K2317/56—Immunoglobulins specific features characterized by immunoglobulin fragments variable (Fv) region, i.e. VH and/or VL
    • C07K2317/567—Framework region [FR]
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/50—Immunoglobulins specific features characterized by immunoglobulin fragments
    • C07K2317/56—Immunoglobulins specific features characterized by immunoglobulin fragments variable (Fv) region, i.e. VH and/or VL
    • C07K2317/569—Single domain, e.g. dAb, sdAb, VHH, VNAR or nanobody®
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/70—Immunoglobulins specific features characterized by effect upon binding to a cell or to an antigen
    • C07K2317/76—Antagonist effect on antigen, e.g. neutralization or inhibition of binding
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/90—Immunoglobulins specific features characterized by (pharmaco)kinetic aspects or by stability of the immunoglobulin
    • C07K2317/92—Affinity (KD), association rate (Ka), dissociation rate (Kd) or EC50 value
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2319/00—Fusion polypeptide
    • C07K2319/30—Non-immunoglobulin-derived peptide or protein having an immunoglobulin constant or Fc region, or a fragment thereof, attached thereto
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2333/00—Assays involving biological materials from specific organisms or of a specific nature
    • G01N2333/005—Assays involving biological materials from specific organisms or of a specific nature from viruses
    • G01N2333/08—RNA viruses
    • G01N2333/165—Coronaviridae, e.g. avian infectious bronchitis virus
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2469/00—Immunoassays for the detection of microorganisms
    • G01N2469/10—Detection of antigens from microorganism in sample from host
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/30—Against vector-borne diseases, e.g. mosquito-borne, fly-borne, tick-borne or waterborne diseases whose impact is exacerbated by climate change

Definitions

  • This application relates to the field of biomedicine, specifically to the construct and application of Nanobody S43, and more specifically to multivalent Nanobodies, Nanobody fusion proteins, and coding based on Nanobody S43 that specifically binds SARS-CoV-2 RBD.
  • Polynucleotides thereof, nucleic acid constructs containing the polynucleotides, expression vectors containing the nucleic acid constructs, transformed cells containing the above polynucleotides, nucleic acid constructs or expression vectors, and medicines containing any of the above products The composition and its application in the preparation of drugs for preventing or treating the new coronavirus, and its application in the preparation of reagents or kits for detecting the new coronavirus or diagnosing the new coronavirus infection.
  • the current COVID-19 outbreak has promoted the development of various vaccines and antiviral drugs.
  • Vaccination can effectively prevent the occurrence of serious infectious diseases.
  • vaccines are only suitable for uninfected people, and the development cycle is long and the clinical research process is complex. For confirmed patients, they can only be treated with antiviral drugs.
  • One of the antiviral drugs is therapeutic antibody drugs, which mainly refer to neutralizing antibodies.
  • Neutralizing antibody drugs mainly prevent the infection by binding to antigens on the surface of pathogenic microorganisms. Specific molecules expressed by pathogenic microorganisms bind to cell surface receptors to achieve a "neutralization" effect.
  • the SARS-CoV-2 virus has a glycosylated spike protein (S) on its surface. The S protein can interact with the host cell receptor protein ACE2 and trigger membrane fusion. Therefore, blocking the binding of the S protein to ACE2 is An effective way to treat COVID-19 infection.
  • S glycosylated spike protein
  • Nanobodies have attracted much attention as therapeutic drugs.
  • the nanobody drug Caplacizumab (Cablivi TM ) developed by Ablynx is used to treat acquired thrombotic thrombocytopenic purpura and is the first nanobody drug approved for marketing;
  • the nanobody drug candidate ALX-0171 is a trivalent form of nanobody used to treat respiratory syncytial virus (RSV) infection in children. It is administered by aerosol and has entered the clinical phase II stage (https://clinicaltrials .gov), these all suggest that nanobody drugs are safe and feasible.
  • RSV respiratory syncytial virus
  • nanobody drugs targeting the new coronavirus and suitable for respiratory mucosal immunity has potential clinical application value and prospects.
  • the purpose of this application is to provide constructs (including multivalent Nanobodies and Nanobody fusion proteins) based on Nanobodies S43 that specifically bind SARS-CoV-2 RBD, polynucleotides encoding them, and nucleic acids containing the polynucleotides.
  • the construct of the present application based on Nanobody S43 that specifically binds SARS-CoV-2 RBD can effectively inhibit SARS-CoV-2 infection and infection of its variant strains, and can Aerosol administration can directly reach the lungs, has a rapid onset of action and a long half-life, providing a more effective treatment strategy for infections caused by the new coronavirus and its mutant strains.
  • the present application provides a multivalent Nanobody, which includes more than two VHH chains of Nanobodies that specifically bind SARS-CoV-2 RBD, wherein the specific binding is SARS-CoV-2 RBD
  • the VHH chain of the Nanobody includes the following CDRs:
  • the amino acid sequence is CDR1 shown in SEQ ID NO:1 (i.e., GFTLDYYAIG),
  • CDR2 with the amino acid sequence shown in SEQ ID NO:2 (i.e., CISSNNSTYYADSVKG), and
  • the amino acid sequence is CDR3 shown in SEQ ID NO:3 (i.e., EPDYSGVYYYTCGWTDFGS).
  • the VHH chain of the Nanobody that specifically binds to the SARS-CoV-2 RBD also includes 4 framework regions FR1-4, the FR1-4 and the CDR1, CDR2 and CDR3 are staggered in order;
  • amino acid sequences of the FR1-4 are respectively as SEQ ID NO:4 (i.e., QVQLQESGGGLVQPGGSLRLTCAPS), SEQ ID NO:5 (i.e., WFRQAPGKEREGVS), SEQ ID NO:6 (i.e., RFTISRDNAKNTVYLQMNSLKPEDTAVYYCAA) and SEQ ID NO: 7 (i.e., WGQGTQVTVSS).
  • SEQ ID NO:4 i.e., QVQLQESGGGLVQPGGSLRLTCAPS
  • SEQ ID NO:5 i.e., WFRQAPGKEREGVS
  • SEQ ID NO:6 i.e., RFTISRDNAKNTVYLQMNSLKPEDTAVYYCAA
  • SEQ ID NO: 7 i.e., WGQGTQVTVSS
  • the VHH chain of the Nanobody that specifically binds to the SARS-CoV-2 RBD has an amino acid sequence as shown in SEQ ID NO:8, or is identical to the amino acid sequence as shown in SEQ ID NO:8 An amino acid sequence having at least 95%, 96%, 97%, 98% or 99% sequence identity; preferably, the amino acid sequence of the VHH chain is as shown in the following SEQ ID NO: 8: Among them, the underlined parts are the framework regions FR1-4 respectively, and the black parts are CDR1, CDR2 and CDR3 of the heavy chain variable region respectively.
  • the multivalent Nanobody is composed of two or more, preferably three, VHH chains of the Nanobody that specifically binds SARS-CoV-2 RBD, connected through a Linker;
  • the multivalent Nanobody is a trivalent Nanobody and has the amino acid sequence shown in SEQ ID NO: 9:
  • the multivalent Nanobody is an IgM pentamer formed from the following fusion protein, and the structure of the fusion protein from the N-terminus to the C-terminus is shown in formula (I): ALB(I)
  • A is a single VHH chain of the Nanobody that specifically binds to the SARS-CoV-2 RBD, or a multivalent Nanobody as described in the preferred embodiment I above;
  • the Fc fragment of human IgM has a structure such as SEQ ID NO: 10 (i.e., VIAELPPKVSVFVPPRDGFFGNPRKSKLICQATGFSPRQIQVSWLREGKQVGSGVTTDQVQAEAKESGPTTYKVTSTLTIKESDWLGQSMFTCRVDHRGLTFQQNASSMCVPDQDTAIRVFAIPPSFASIFLTKSTKLTCLVTDLTTYDSVTISWTRQNGEAVKTHTNISESHPNATFSAVGEASICEDDWNSGERFTCTVTHTDLPSPLKQTISRPKG VALHRPDVYLLPPAREQLNLRESATITCLVTGFSPADVFVQWMQRGQPLSPEKYVTSAPMPEPQAPGRYFAHSILTVSEEEWNTGETYTCVVAHEALPNRVTERTVDKSTGKPTLYNVSLVMSDTAGTCY), or an amino acid sequence having at least 95%, 96%, 97%, 98% or
  • the present application provides a Nanobody fusion protein.
  • the structure of the Nanobody fusion protein from the N-terminus to the C-terminus is as shown in Formula (I): ALB(I)
  • the Fc fragment of human IgM is the Fc fragment of human IgM; preferably, the Fc fragment of human IgM has the amino acid sequence shown in SEQ ID NO: 10, or has at least 95%, 96% of the amino acid sequence shown in SEQ ID NO: 10 An amino acid sequence with %, 97%, 98% or 99% sequence identity;
  • the above fusion protein has the amino acid sequence shown in SEQ ID NO: 11.
  • the present application provides a polynucleotide encoding a multivalent Nanobody as described in the above first aspect, or encoding a Nanobody fusion protein as described in the above second aspect.
  • the polynucleotide is DNA or mRNA
  • the polynucleotide encodes a multivalent Nanobody according to the preferred specific embodiment 1 of the above-mentioned first aspect.
  • the polynucleotide includes as shown in SEQ ID NO: 12 (i.e., ) Nucleotide sequence;
  • the polynucleotide encodes a Nanobody fusion protein as described in the second aspect above.
  • the polynucleotide includes a protein such as SEQ ID NO: 13 (i.e., CAGGGTGCAGCTGCAGGAGAGCGGAGGAGGGCTGGTGCAGCCCGGAGGAAGCCTGAGACTGACCTGCGCCCCCAGCGGATTCACCCTGGATTATTATGCTATTGGCTGGTTTAGGCAGGCTCCCGGCAAAGAGAGAGGGGGTGTCATGCATTAGCAGCAATAACTCAACCTACTAC GCCGACAGCGTCAAGGGACGCTTCACCATTTCCAGGGACAACGC ) the nucleotide sequence shown.
  • the present application provides a nucleic acid construct comprising the polynucleotide as described in the third aspect above, and optionally, at least one expression control element operably linked to the polynucleotide.
  • at least one expression control element operably linked to the polynucleotide. For example, histidine tag, stop codon, etc.
  • the present application provides an expression vector comprising the nucleic acid construct described in the fourth aspect.
  • the present application provides a transformed cell, which includes the polynucleotide as described in the third aspect, the nucleic acid construct as described in the fourth aspect, or the expression vector as described in the fifth aspect. .
  • the present application provides a pharmaceutical composition, which includes the multivalent Nanobody as described in the first aspect, the Nanobody fusion protein as described in the second aspect, and the nanobody fusion protein as described in the third aspect.
  • a pharmaceutical composition which includes the multivalent Nanobody as described in the first aspect, the Nanobody fusion protein as described in the second aspect, and the nanobody fusion protein as described in the third aspect.
  • the pharmaceutical composition may be a nasal spray, oral formulation, suppository, or parenteral formulation form;
  • the nasal spray is selected from aerosols, sprays and powder sprays;
  • the oral preparation is selected from tablets, powders, pills, powders, granules, fine granules, soft/hard capsules, film-coated agents, pellets, sublingual tablets and ointments;
  • the parenteral preparation is a transdermal preparation, an ointment, a plaster, a topical liquid, an injectable or a pushable preparation.
  • the dosage of the active ingredient of the pharmaceutical composition of the present application varies depending on the administration target, the target organ, symptoms, administration method, etc., and may take into consideration the type of dosage form, administration method, age and weight of the patient, The patient's symptoms, etc., are determined based on the doctor's judgment.
  • the present application provides a multivalent Nanobody as described in the first aspect, a Nanobody fusion protein as described in the second aspect, a polynucleotide as described in the third aspect,
  • the nucleic acid construct described in the fourth aspect, the expression vector described in the fifth aspect, the transformed cell described in the sixth aspect or the pharmaceutical composition described in the seventh aspect are used for the prevention and treatment of /or application in drugs to treat novel coronavirus infection.
  • the new coronavirus can be the original strain of SARS-CoV-2 and/or the mutant strain of SARS-CoV-2;
  • the SARS-CoV-2 variant strains are Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Kappa (B.1.617.1), Delta (B. 1.617.2) strain, Omicron (B.1.1.529) subtype BA.1 strain or Omicron (B.1.1.529) subtype BA.2 strain; further preferably, the SARS-CoV-2 The mutated strains are Delta (B.1.617.2) strain, Omicron (B.1.1.529) subtype BA.1 strain or Omicron (B.1.1.529) subtype BA.2 strain.
  • the present application provides a multivalent Nanobody as described in the first aspect, a Nanobody fusion protein as described in the second aspect, a polynucleotide as described in the third aspect,
  • the nucleic acid construct described in the fourth aspect, the expression vector as described in the fifth aspect, or the transformed cells as described in the sixth aspect are used in preparing reagents for detecting a new coronavirus or for diagnosing a new coronavirus infection. or application in a kit.
  • the new coronavirus can be the original strain of SARS-CoV-2 and/or the mutant strain of SARS-CoV-2;
  • the SARS-CoV-2 variant strains are Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Kappa (B.1.617.1), Delta (B. 1.617.2) strain, Omicron (B.1.1.529) subtype BA.1 strain or Omicron (B.1.1.529) subtype BA.2 strain; further preferably, the SARS-CoV-2 The mutated strains are Delta (B.1.617.2) strain, Omicron (B.1.1.529) subtype BA.1 strain or Omicron (B.1.1.529) subtype BA.2 strain.
  • the present application provides a novel coronavirus detection kit, which includes the multivalent Nanobody as described in the above first aspect, the Nanobody fusion protein as described in the above second aspect, and the above third aspect. described Polynucleotide, the nucleic acid construct as described in the fourth aspect, the expression vector as described in the fifth aspect, or the transformed cell as described in the sixth aspect.
  • This application is for the drug development of nanobody constructs for the new coronavirus.
  • the constructs based on Nanobody S43 of this application can bind to SARS-CoV-2 RBD with high affinity and can neutralize SARS-CoV-2 with high neutralizing activity.
  • Virus (SARS-CoV-2) Nanobodies Nanobodies.
  • the inventors have demonstrated through a series of experiments that the trivalent Nanobody (TS43) and IgM pentameric form (MS43) based on Nanobody S43 of the present application have significantly improved performance compared to its monomer (i.e., Nanobody S43). With its neutralizing activity and significantly extended half-life, it achieves mucosal immunity, can limit the reproduction of the virus and further cross the mucosal barrier, control the mucosal spread of the virus, and provides a potential aerosolized solution for the clinical prevention and treatment of the new coronavirus.
  • the new antibody drug administered can achieve sensitive and reliable detection of the new coronavirus.
  • Figure 1 is a schematic structural diagram of the Nanobody constructs TS43 and MS43 constructed in Example 1 of the present application;
  • Figure 2 is a diagram of the S43 protein molecular sieve chromatography and SDS-PAGE identification results described in Example 1 of the present application;
  • Figure 3 is a diagram of the TS43 protein molecular sieve chromatography and SDS-PAGE identification results described in Example 1 of the present application;
  • Figure 4 is a diagram of the MS43 protein molecular sieve chromatography and SDS-PAGE identification results described in Example 1 of the present application;
  • Figure 5 is the SARS-CoV-2 RBD-his protein (A) described in Example 2 of the present application, the RBD-his protein (B) of the mutant strain Omicron (B.1.1.529) subtype BA.1 and SDS-PAGE identification results of RBD-his protein (C) of Omicron (B.1.1.529) subtype BA.2.
  • Figure 6 is a schematic diagram of the effect of the three antibodies measured in Example 5 of the present application on neutralizing SARS-CoV-2 prototype strain pseudovirus infection.
  • Figure 7 is a schematic diagram of the effect of the three antibodies measured in Example 5 of the present application on neutralizing SARS-CoV-2 variant strain Delta (B.1.617.2) pseudovirus infection.
  • Figure 8 is a schematic diagram of the effect of the three antibodies measured in Example 5 of the present application on neutralizing SARS-CoV-2 variant strain Omicron (B.1.1.529) subtype BA.1 pseudovirus infection.
  • Figure 9 is a schematic diagram of the effect of the three antibodies measured in Example 5 of the present application on neutralizing SARS-CoV-2 variant strain Omicron (B.1.1.529) subtype BA.2 pseudovirus infection.
  • Figure 10 is the neutralizing activity of the three antibodies measured in Example 7 of the present application against pseudovirus before and after aerosolization; Among them, A is the neutralizing activity result of Nanobody S43 against SARS-CoV-2 prototype strain pseudovirus before and after aerosolization, and B is the neutralizing activity of Nanobody construct TS43 against SARS-CoV-2 prototype strain pseudovirus. and activity results, C is the neutralizing activity result of Nanobody construct MS43 against SARS-CoV-2 variant strain Delta (B.1.617.2) pseudovirus.
  • “Nanobody” is a “heavy chain single domain antibody”. This type of antibody only contains a heavy chain variable region (VHH, variable domain of heavy chain of heavy-chain antibody). Compared with other antibodies, the light chain is naturally missing. .
  • nanobodies Due to their biophysical advantages, nanobodies can be easily atomized and delivered directly to the lungs through inhalers to treat infections caused by respiratory viruses and are considered to be very promising antibody-based drugs.
  • binding refers to the determination of the presence or absence of said protein, such as the Nanobodies of the present application, in a heterogeneous population of proteins and/or other biological agents. Binding reaction with SARS-CoV-2 RBD protein. Thus, under specified conditions, a specific ligand/antigen binds to a specific receptor/antibody and does not bind in significant amounts to other proteins present in the sample.
  • reagents, enzymes, culture media, antibiotics, milk and other chemical materials used in the following examples of this application are all commercially available products.
  • TRIzol is purchased from Invitrogen
  • Superscript II First-Strand Synthesis System for RT-PCR kit is purchased from Invitrogen.
  • pCAGGS vector was purchased from MiaoLingPlasmid
  • 293F cells, HEK293T cells, etc. were purchased from ATCC
  • Series Sensor Chip SA chip Purchased from GE Healthcare
  • Vero cells were purchased from ATCC CCL81.
  • coding sequence of TS43 in this application was synthesized by Beijing Qingke Biotechnology Co., Ltd.
  • Example 1 Construction, expression and purification of antibodies based on the trivalent form (TS43) and IgM pentameric form (MS43) of Nanobody S43
  • the basic nanobody S43 used in this laboratory was obtained by immunizing alpacas with SARS-CoV-2S protein, constructing an antibody library, and screening using phage display technology; the amino acid sequence of the VHH chain of single-chain nanobody S43 is as SEQ ID As shown in NO: 8, it can bind SARS-CoV-2 RBD with high affinity and specificity (binding constant is 1.2E-10 ⁇ 1.4E-11M), and in pseudovirus neutralization experiments, it can neutralize with high Activity neutralizes SARS-CoV-2 pseudovirus, all of which indicate that S43 nanobody is a novel coronavirus (SARS-CoV-2) sheep that can bind to SARS-CoV-2 RBD with high affinity and has high neutralizing activity. Camel-derived nanobodies.
  • SARS-CoV-2 novel coronavirus
  • a signal peptide (ATMHSSALLCCLVLLTGVRA, SEQ ID NO:15) is connected to the 5' end of the coding sequence of the S43VHH chain of the above-mentioned single-chain Nanobody (as shown in SEQ ID NO: 14), and 6 histidine tags are connected to the 3' end ( hexa-His-tag) and the translation stop codon TGA, it was constructed into the pCAGGS vector (purchased from Invitrogen) through the restriction endonuclease sites EcoRI and XhoI, and then the resulting recombinant vector was transfected into 293F In cells (purchased from Invitrogen), S43-his protein was expressed.
  • the coding sequences of the three Nanobody S43VHH chains shown in SEQ ID NO: 14 are connected in a head-to-tail format (directly synthesized by Beijing Qingke Biotechnology Co., Ltd.), and in their 5
  • the 'end is connected to the signal peptide (ATMHSSALLCCLVLLTGVRA, SEQ ID NO:15)
  • the 3' end is connected to the coding sequence of 6 histidine tags (hexa-His-tag) and the translation stop codon TGA, through the restriction endonuclease site EcoRI and XhoI were spotted and constructed into the pCAGGS vector (purchased from Invitrogen), and then the resulting recombinant vector was transfected into 293F cells (purchased from Invitrogen) to express TS43-his protein.
  • the coding sequence of the Nanobody S43VHH chain (shown in SEQ ID NO:14) was connected to the coding sequence of the Fc of the human IgM antibody (shown in SEQ ID NO:16), and at 5 The 'end is connected to a signal peptide (ATMHSSALLCCLVLLTGVRA, SEQ ID NO: 15), the 3' end is connected to the translation stop codon TGA, and it is constructed into the pCAGGS vector (purchased from Invitrogen) through the restriction endonuclease sites EcoRI and XhoI. The pCAGGS-S43-IgM Fc recombinant expression vector was obtained.
  • the coding sequence of the J chain (Joining chain) (such as SEQ ID NO:17
  • the translation stop codon TGA was connected to the 3' end of (shown), and it was constructed into the pCAGGS vector (purchased from Invitrogen) through the restriction endonuclease sites EcoRI and XhoI to obtain the pCAGGS-J chain recombinant expression vector.
  • the above two recombinant expression vectors pCAGGS-S43-IgM Fc and pCAGGS-J chain were co-transfected into 293F cells (purchased from Invitrogen) to express the S43-IgM Fc fusion protein and J chain, and the two were then self-assembled.
  • MS43 protein forming the IgM form of MS43 protein.
  • the obtained MS43 protein was purified by HiTrap TM IgM Purification HP (GE Healthcare) and Superose TM 6 increase 10/300GL (GE Healthcare), and then identified by SDS-PAGE.
  • the SDS-PAGE identification size of MS43 protein is about 70KD, and the results are shown in Figure 4.
  • the coding sequence of the RBD protein (the amino acid sequence of which is shown in SEQ ID NO: 19) of the SARS-CoV-2 variant strain Omicron (B.1.1.529) subtype BA.1 and Omicron (B.1.1.529 )
  • the 3' end of the coding sequence of the RBD protein of subtype BA.2 (the amino acid sequence of which is shown in SEQ ID NO: 20) is connected to the coding sequence and translation of 6 histidine tags (hexa-His-tag). Stop codon TGA, expressed by bac-to-bac baculovirus expression system (Invitrogen).
  • bacmids Transform the pFastbac1 plasmid containing the target gene into DH10Bac competent cells to generate recombinant bacmids (bacmids).
  • the recombinant bacmid bacmids were transfected into Sf9 cells for virus amplification, and protein expression was performed in Hi5 cells. After 48 h of expression, the Hi5 cell supernatant was collected, and the soluble protein was purified by nickel affinity chromatography using HisTrap TM excel (GE Healthcare).
  • the cell culture medium containing the target protein is purified by the nickel ion affinity chromatography column HisTrap TM excel (GE Healthcare) and the gel filtration chromatography Superdex TM 200 Increase 10/300GL column (GE Healthcare), a relatively pure target protein can be obtained.
  • SARS-CoV-2 RBD-his protein, RBD-his protein of mutant strain Omicron (B.1.1.529) subtype BA.1, and RBD-his protein of Omicron (B.1.1.529) subtype BA.2 The SDS-PAGE identification size is about 30KD, as shown in Figures 5A to C respectively.
  • Example 3 Surface plasmon resonance technology detects the binding ability of each antibody to the RBD protein of the original strain of SARS-CoV-2 and its mutant strains
  • the single-chain Nanobody S43 and its constructs TS43 and MS43 prepared in the above examples were biotinylated respectively, and then immobilized on the Series Sensor Chip SA chip (Cytiva Life Sciences); PBST buffer (2.7mM KCl, 137mM NaCl, 4.3mM Na 2 HPO 4 , 1.4mM KH 2 PO 4 , 0.05% Tween) respectively.
  • PBST buffer 2.7mM KCl, 137mM NaCl, 4.3mM Na 2 HPO 4 , 1.4mM KH 2 PO 4 , 0.05% Tween
  • the RBD proteins of the original SARS-CoV-2 strain and its mutant strains prepared in the Example were diluted multiple times and loaded onto the chip one by one from low concentration to high concentration. Calculation of binding kinetic constants was performed using BIAevaluation software 8K (Biacore, Inc.).
  • the equilibrium dissociation constant (K D ) between each antibody and each RBD is shown in Table 1.
  • the results in Table 1 show that the single-chain nanobody S43 and its constructs TS43 and MS43 can all interact with the SARS-CoV-2 prototype strain. And the RBD proteins of mutant strains Omicron subtype BA.1 and Omicron subtype BA.2 bind with higher affinity.
  • the packaging steps for SARS-CoV-2 original strain and mutant strain pseudovirus are as follows:
  • HEK293T cells purchased from ATCC CRL-3216
  • the culture medium was DMEM medium containing 10% FBS.
  • Transfection Take the expression plasmid of each S protein in the above step 2), and use PEI to transfect 30 ⁇ g plasmid/10cm cell culture dish. Mix the target plasmid and PEI in a ratio of 1:3 before transfection, and transfect after 4-6 hours. Culture medium (DMEM medium containing 10% FBS), culture at 37°C for 24 hours.
  • Toxin addition Add the pseudovirus packaging skeleton virus G*VSV-delG (purchased from Wuhan Shumi Brain Science and Technology Co., Ltd.) to the above-transfected HEK293T cells, incubate at 37°C for 2 hours, and change the culture medium (containing 10% FBS) DMEM medium), and add VSV-G antibody (hybridoma cells expressing this antibody were purchased from ATCC cell bank), and continue to culture in the incubator for 30 h.
  • G*VSV-delG purchased from Wuhan Shumi Brain Science and Technology Co., Ltd.
  • Toxin collection Collect the supernatant and centrifuge it at 3000rpm for 10 minutes, filter it through a 0.45 ⁇ m sterile filter in a clean workbench. Remove cell debris, aliquot, and freeze in -80°C refrigerator.
  • SARS-CoV-2 prototype strain SARS-CoV-2WT
  • variant strains Delta B.1.617.2
  • Omicron B.1.1.529
  • subtypes BA.1 and Omicron B.1.1. 529) Pseudovirus of subtype BA.2.
  • the purified single-chain Nanobody S43 and its constructs TS43 and MS43 (prepared from Example 1) were diluted 5-fold to the ninth gradient (2.56pg/mL), and the dilution was mixed with 1.6 ⁇ 10 4 TCID 50
  • a series of pseudoviruses of the original SARS-CoV-2 strain and variant strains obtained in Example 4 were mixed separately, mixed and incubated at 37°C for 1 hour, and then added to 96 cells pre-inoculated with Vero cells (purchased from ATCC CCL81) in the orifice plate. After incubation for 18 to 20 hours, it was detected by CQ1 Confocal Quantitative Image Cytometer (Yokogawa).
  • IC 50 ( ⁇ g/mL) is the half inhibitory concentration of the antibody. *Indicates that the highest concentration of 10 mg/mL has not yet reached 100% inhibition rate.
  • CPE cytopathic effect
  • the purified single-chain Nanobody S43 and its TS43 and MS43 (prepared in Example 1) were diluted 2-fold to the 11th gradient, with 4 replicate wells for each gradient, 50 ⁇ L per well, and the diluent was Incubate with an equal volume of 100 TCID 50 of the original SARS-CoV-2 strain or its variant strain Delta and Omicron subtype BA.1 at 37°C. After 1 hour, the mixture was added to the suspended Vero cells and incubation was continued at 37°C for 3 days. Observe and record cell lesions. IC50 of Nanobodies and their constructs were calculated using GraphPad Prism 7.0. The experiments were all conducted in the biosafety level three laboratory (BSL3) of the Chinese Center for Disease Control and Prevention.
  • BSL3 biosafety level three laboratory
  • the live virus neutralizing effects of the single-chain nanobody S43 and its TS43 and MS43 on the original strain of the new coronavirus and its mutant strains are shown in Table 3.
  • the results in Table 3 show: The effect of TS43 and MS43 on the original strain and the mutant strain of the new coronavirus. Live viruses all have good inhibitory effects.
  • IC 50 ( ⁇ g/mL) is the half inhibitory concentration of the antibody.
  • Example 7 Detection of antibody stability before and after atomization
  • the single-chain Nanobody S43 and its constructs TS43 and MS43 were atomized using an Aerogen Solo (Aerogen Inc., Chicago, USA) nebulizer, respectively, and then used in an all-glass SKC (Eighty Four, PA, USA) containing 20 mL of PBS. ) Collect the aerosolized antibodies and conduct a pseudovirus neutralization test as described in Example 5.
  • the construct of the present application based on the nanobody S43 that specifically binds to the SARS-CoV-2 RBD can effectively inhibit SARS-CoV-2 infection and its variant strain infection. It can be administered by aerosol, can directly reach the lungs, and has a rapid onset of effect. , and has a long half-life, providing a more effective treatment option for the clinical prevention or treatment of infections caused by the new coronavirus and its mutant strains.

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Abstract

提供了基于特异性结合SARS-CoV-2 RBD的纳米抗体S43的构建体(包括多价纳米抗体和纳米抗体融合蛋白)、其相关产品及其应用；所述基于特异性结合SARS-CoV-2 RBD的纳米抗体S43的构建体(包括多价纳米抗体和纳米抗体融合蛋白)能有效抑制SARS-CoV-2感染及其变异毒株感染，可以雾化给药，能直达肺部，起效较快，且半衰期长，为临床上预防或治疗新冠病毒及其变异株感染提供了更有效的治疗策略。

Description

纳米抗体S43的构建体及其应用
交叉引用
本申请要求于2022年3月21日提交的、申请号为202210278937.X、发明名称为“纳米抗体S43的构建体及其应用”的中国专利申请的优先权，其全部内容通过引用并入本文。
技术领域
本申请涉及生物医药领域，具体涉及纳米抗体S43的构建体及其应用，更具体地，涉及基于特异性结合SARS-CoV-2 RBD的纳米抗体S43的多价纳米抗体、纳米抗体融合蛋白、编码其的多核苷酸、包含该多核苷酸的核酸构建体、包含该核酸构建体的表达载体、包含上述多核苷酸、核酸构建体或表达载体的转化的细胞以及包含上述任一项产品的药物组合物及其在制备用于预防或治疗新型冠状病毒的药物中的应用、在制备用于检测新型冠状病毒或诊断新型冠状病毒感染的试剂或试剂盒中的应用。
背景技术
2019年12月以来，由冠状病毒科(family Coronaviridae)的新型冠状病毒(SARS-CoV-2)引起的疫情在全球范围内仍不断蔓延。除此之外，同属冠状病毒科的严重急性呼吸综合征冠状病毒(SARS-CoV)、中东呼吸综合征冠状病毒(MERS-CoV)等也是针对人类呼吸系统的主要病原体，主要通过飞沫、气溶胶和接触等方式传播，其传染性强，易引起群众恐慌，因此这类引起呼吸系统疾病的病毒严重危害公共卫生安全，尤其近年来呼吸性传染病的频发、病毒的不断变异，对人民群众的身体健康、生命安全和国民经济发展、社会稳定造成极大威胁。
当前的新冠肺炎疫情暴发推动了各种疫苗和抗病毒药物的开发，其中接种疫苗可有效预防严重传染疾病的发生，但是疫苗的适用对象为未感染人群，且研发周期长，临床研究过程复杂。而对于确诊患者而言，只能通过抗病毒药物进行治疗，其中一种抗病毒药物是治疗性抗体药物，主要指中和抗体；中和抗体药物主要是通过与病原微生物表面的抗原结合，阻止病原微生物表达的特定分子与细胞表面受体结合，达到“中和”的效果。SARS-CoV-2病毒表面具有糖基化的刺突蛋白(spike protein,S)，该S蛋白能与宿主细胞受体蛋白ACE2相互作用并触发膜融合，因此阻断S蛋白与ACE2的结合是治疗新冠病毒感染的有效途径。
常规单克隆抗体，一般通过静脉注射给药，然而，通过静脉注射途径给药的单克隆抗体从全身循环进入肺部的药物浓度非常低，大大降低了中和抗体本身的抗病毒效果，导致不能有效降低肺部的病毒载量。新型冠状病毒最初感染上呼吸道，它与免疫系统的 第一次相互作用主要发生在呼吸道黏膜表面，鉴于此，对于通过呼吸道感染的新冠病毒而言，在关注血清抗体的同时，还有必要从黏膜免疫的角度去思考、设计和开发合适的抗体类药物。例如，雾化给药可使抗体药物在呼吸道内达到更高的局部浓度，能在病毒入侵时更有效地阻断病毒感染。
纳米抗体作为治疗性药物已备受关注，例如，由Ablynx公司研发的纳米抗体药物Caplacizumab(CabliviTM)用于治疗获得性血栓性血小板减少性紫癜，是首个获批上市的纳米抗体药物；再如，纳米抗体候选药物ALX-0171是一种用于治疗小儿呼吸道合胞病毒(RSV)感染的三价形式的纳米抗体，采用雾化给药，已进入临床Ⅱ期阶段(https://clinicaltrials.gov)，这些都提示：纳米抗体药物具有安全性、可行性。
因此，开发针对新型冠状病毒的、适于呼吸道黏膜免疫的纳米抗体药物具有潜在的临床应用价值与前景。
发明内容
发明目的
本申请的目的在于提供基于特异性结合SARS-CoV-2 RBD的纳米抗体S43的构建体(包括多价纳米抗体和纳米抗体融合蛋白)、编码其的多核苷酸、包含该多核苷酸的核酸构建体、包含该核酸构建体的表达载体、包含上述多核苷酸、核酸构建体或表达载体的转化的细胞以及包含上述任一项产品的药物组合物及其在制备用于预防或治疗新型冠状病毒的药物中的应用、在制备用于检测新型冠状病毒或诊断新型冠状病毒感染的试剂或试剂盒中的应用。
本申请的基于特异性结合SARS-CoV-2 RBD的纳米抗体S43的构建体(包括多价纳米抗体和纳米抗体融合蛋白)，能有效抑制SARS-CoV-2感染及其变异毒株感染，可以雾化给药，能直达肺部，起效较快且半衰期长，为新冠病毒及其变异株感染提供了更有效的治疗策略。
解决方案
为实现上述目的，本申请提供了如下技术方案：
第一方面，本申请提供了一种多价纳米抗体，其包括两条以上、特异性结合SARS-CoV-2 RBD的纳米抗体的VHH链，其中，所述特异性结合SARS-CoV-2 RBD的纳米抗体的VHH链包括以下CDR：
氨基酸序列如SEQ ID NO:1(即，GFTLDYYAIG)所示的CDR1，
氨基酸序列如SEQ ID NO:2(即，CISSNNSTYYADSVKG)所示的CDR2，以及
氨基酸序列如SEQ ID NO:3(即，EPDYSGVYYYTCGWTDFGS)所示的CDR3。
在具体实施方案中，所述特异性结合SARS-CoV-2 RBD的纳米抗体的VHH链还包括 4个框架区FR1-4，所述FR1-4与所述CDR1、CDR2和CDR3按顺序交错排列；
优选地，所述FR1-4的氨基酸序列分别如SEQ ID NO:4(即，QVQLQESGGGLVQPGGSLRLTCAPS)、SEQ ID NO:5(即，WFRQAPGKEREGVS)、SEQ ID NO:6(即，RFTISRDNAKNTVYLQMNSLKPEDTAVYYCAA)和SEQ ID NO:7(即，WGQGTQVTVSS)所示。
在优选的具体实施方案中，所述特异性结合SARS-CoV-2 RBD的纳米抗体的VHH链具有如SEQ ID NO:8所示的氨基酸序列，或与SEQ ID NO:8所示的氨基酸序列具有至少95％，96％，97％，98％或99％序列同一性的氨基酸序列；优选地，所述VHH链的氨基酸序列如以下SEQ ID NO:8所示：
其中，下划线部分分别为框架区FR1-4，标黑部分分别为重链可变区的CDR1、CDR2和CDR3。
在优选的具体实施方案I中，所述多价纳米抗体由两条以上、优选地三条所述特异性结合SARS-CoV-2 RBD的纳米抗体的VHH链通过Linker连接构成；
其中，所述Linker为(GGGGS)n，其中，n＝1,2,3,或4，优选地，n＝2或3。
作为具体实施方案I的进一步优选，所述多价纳米抗体为三价纳米抗体，具有如SEQ ID NO:9所示的氨基酸序列：
在优选的具体实施方案II中，所述多价纳米抗体为由以下融合蛋白形成的IgM五聚体，所述融合蛋白从N端到C端的结构如式(I)所示：
A-L-B  (I)
其中，
A为单条、所述特异性结合SARS-CoV-2 RBD的纳米抗体的VHH链，或者为如上述优选的具体实施方案I中所述的多价纳米抗体；
B为人源IgM的Fc片段；优选地，所述人源IgM的Fc片段具有如SEQ ID NO:10(即， VIAELPPKVSVFVPPRDGFFGNPRKSKLICQATGFSPRQIQVSWLREGKQVGSGVTTDQVQAEAKESGPTTYKVTSTLTIKESDWLGQSMFTCRVDHRGLTFQQNASSMCVPDQDTAIRVFAIPPSFASIFLTKSTKLTCLVTDLTTYDSVTISWTRQNGEAVKTHTNISESHPNATFSAVGEASICEDDWNSGERFTCTVTHTDLPSPLKQTISRPKGVALHRPDVYLLPPAREQLNLRESATITCLVTGFSPADVFVQWMQRGQPLSPEKYVTSAPMPEPQAPGRYFAHSILTVSEEEWNTGETYTCVVAHEALPNRVTERTVDKSTGKPTLYNVSLVMSDTAGTCY)所示的氨基酸序列，或与SEQ ID NO:10所示的氨基酸序列具有至少95％，96％，97％，98％或99％序列同一性的氨基酸序列；
L为(GGGGS)m，其中，m＝0,1,2,3,或4。
作为上述融合蛋白的优选实施方案，其具有如SEQ ID NO:11所示的氨基酸序列：
第二方面，本申请提供了一种纳米抗体融合蛋白，所述纳米抗体融合蛋白从N端到C端的结构如式(I)所示：
A-L-B  (I)
其中，
A为单条、特异性结合SARS-CoV-2 RBD的纳米抗体的VHH链，所述特异性结合SARS-CoV-2 RBD的纳米抗体的VHH链如上述第一方面中所定义；或者，A为根据上述第一方面的优选的具体实施方案I中所述的多价纳米抗体，即，由两条以上、优选地三条所述特异性结合SARS-CoV-2 RBD的纳米抗体的VHH链通过Linker连接构成的多价纳米抗体，其中，所述Linker为(GGGGS)n，其中，n＝1,2,3,或4，优选地，n＝2或3；
B为人源IgM的Fc片段；优选地，所述人源IgM的Fc片段具有如SEQ ID NO:10所示的氨基酸序列，或与SEQ ID NO:10所示的氨基酸序列具有至少95％，96％，97％，98％或99％序列同一性的氨基酸序列；
L为(GGGGS)m，其中，m＝0,1,2,3,或4。
作为上述融合蛋白的优选实施方案，其具有如SEQ ID NO:11所示的氨基酸序列。
第三方面，本申请提供了一种多核苷酸，其编码如上述第一方面所述的多价纳米抗体，或者编码如上述第二方面所述的纳米抗体融合蛋白。
在具体实施方案中，所述多核苷酸为DNA或mRNA；
优选地，所述多核苷酸编码根据上述第一方面的优选的具体实施方案I的多价纳米抗体，进一步优选地，所述多核苷酸包括如SEQ ID NO:12(即，CAGGTCCAACTCCAAGAGAGCGGCGGCGGCCTCGTCCAACCCGGAGGATCACTCAGACTCACATGCGCCCCAAGCGGCTTCACACTCGACTACTACGCCATCGGCTGGTTCAGACAAGCCCCCGGCAAAGAGAGAGAAGGAGTGTCTTGCATTAGCAGCAACAACAGCACCTACTACGCCGACAGTGTCAAAGGAAGATTCACCATCAGCAGGGACAACGCTAAGAACACCGTGTATCTCCAGATGAACTCACTGAAGCCCGAGGACACCGCCGTGTACTACTGCGCCGCCGAGCCCGACTACAGCGGCGTTTACTACTACACCTGCGGATGGACCGACTTCGGCAGCTGGGGCCAAGGAACCCAAGTCACCGTGAGCAGCGGAGGCGGAGGAAGCGGCGGTGGAGGAAGTGGCGGAGGCGGATCTGGGGGGGGAGGATCAGGCGGAGGAGGAAGCCAGGTGCAGCTGCAGGAGAGCGGAGGAGGACTGGTGCAGCCAGGAGGAAGCCTGAGACTGACATGCGCACCAAGCGGATTCACACTGGACTATTATGCTATCGGATGGTTCAGACAGGCCCCTGGAAAAGAGAGAGAGGGGGTGAGCTGCATCAGCAGCAATAACTCCACATACTACGCCGATAGCGTCAAGGGGAGGTTCACTATTAGCAGGGACAATGCAAAGAACACAGTGTACCTGCAGATGAACAGCCTGAAGCCCGAAGACACCGCCGTCTACTACTGCGCAGCCGAGCCCGATTACAGCGGCGTGTACTACTACACATGCGGATGGACAGACTTCGGCTCCTGGGGCCAAGGCACCCAAGTGACCGTGTCAAGCGGAGGCGGGGGGAGCGGAGGAGGTGGAAGTGGAGGGGGGGGATCTGGCGGGGGAGGAAGTGGAGGAGGAGGATCACAGGTGCAGCTCCAGGAGAGCGGGGGAGGACTGGTCCAGCCAGGAGGGAGCCTGAGACTCACATGTGCACCCAGCGGATTTACACTGGATTATTACGCCATCGGATGGTTTAGGCAGGCACCCGGGAAAGAGAGAGAGGGCGTGAGCTGCATTAGCAGTAATAACAGCACCTATTACGCCGACTCAGTGAAGGGGCGGTTCACCATAAGCAGGGATAACGCCAAGAACACCGTCTACCTGCAGATGAATAGCCTGAAACCCGAAGACACAGCCGTGTACTATTGCGCCGCCGAACCCGACTACTCTGGAGTGTACTACTATACCTGCGGCTGGACCGACTTTGGCAGCTGGGGGCAAGGCACCCAGGTGACCGTGAGCAGT)所示的核苷酸序列；
优选地，所述多核苷酸编码如上述第二方面所述的纳米抗体融合蛋白，进一步优选地，所述多核苷酸包括如SEQ ID NO:13(即，CAGGTGCAGCTGCAGGAGAGCGGAGGAGGGCTGGTGCAGCCCGGAGGAAGCCTGAGACTGACCTGCGCCCCCAGCGGATTCACCCTGGATTATTATGCTATTGGCTGGTTTAGGCAGGCTCCCGGCAAAGAGAGAGAGGGGGTGTCATGCATTAGCAGCAATAACTCAACCTACTACGCCGACAGCGTCAAGGGACGCTTCACCATTTCCAGGGACAACGC TAAGAACACCGTGTATCTCCAGATGAATAGCCTGAAGCCCGAGGACACCGCAGTGTACTACTGCGCCGCCGAGCCCGACTACAGCGGTGTGTATTACTACACCTGCGGATGGACCGACTTCGGCAGCTGGGGCCAGGGAACCCAGGTGACAGTGAGCAGCGTGATCGCCGAGCTGCCCCCCAAGGTGAGCGTGTTCGTGCCCCCTAGAGACGGCTTCTTCGGCAACCCTAGAAAGAGCAAGCTGATCTGCCAAGCCACCGGCTTCTCCCCTAGACAGATCCAAGTGAGCTGGCTGAGAGAGGGCAAGCAAGTGGGCAGCGGCGTCACAACAGACCAAGTGCAAGCCGAGGCCAAGGAGAGCGGCCCCACCACCTACAAGGTGACAAGCACCCTGACCATCAAGGAGAGCGACTGGCTGGGGCAGAGCATGTTCACCTGCAGAGTGGACCACAGAGGCCTGACCTTTCAGCAGAACGCTAGCAGCATGTGCGTGCCCGACCAAGACACCGCCATCAGAGTGTTCGCCATCCCCCCTAGCTTCGCTAGCATCTTCCTGACCAAGAGCACCAAGCTGACCTGCCTCGTGACCGATCTGACCACCTACGACAGCGTGACCATCAGCTGGACAAGACAGAACGGCGAGGCCGTGAAGACCCACACCAACATCAGCGAGAGCCACCCCAACGCCACCTTCAGCGCCGTGGGCGAGGCTAGCATCTGCGAGGACGACTGGAACAGCGGCGAGAGATTCACCTGCACCGTGACCCACACCGACCTGCCTAGCCCCCTGAAGCAGACCATCAGCAGACCCAAGGGCGTGGCCCTGCACAGACCCGACGTGTACCTGCTGCCCCCCGCTAGAGAGCAGCTGAACCTGAGAGAGAGCGCCACCATCACCTGCCTGGTGACCGGCTTTAGCCCCGCTGACGTGTTCGTGCAGTGGATGCAGAGAGGGCAGCCCCTGAGCCCCGAGAAGTACGTGACAAGCGCCCCCATGCCCGAGCCCCAAGCCCCCGGCAGATACTTCGCCCACAGCATCCTGACCGTGAGCGAGGAAGAGTGGAACACCGGCGAGACCTACACCTGCGTGGTGGCCCACGAGGCCCTGCCCAACAGAGTGACCGAGAGAACCGTGGACAAGAGCACCGGCAAGCCCACCCTGTACAACGTGAGCCTGGTGATGAGCGACACCGCCGGCACCTGCTAC)所示的核苷酸序列。
第四方面，本申请提供了一种核酸构建体，其包含如上述第三方面所述的多核苷酸，以及任选地，与所述多核苷酸可操作地连接的至少一个表达调控元件。例如组氨酸标签、终止密码子等。
第五方面，本申请提供了一种表达载体，其包含如上述第四方面所述的核酸构建体。
第六方面，本申请提供了一种转化的细胞，其包括如上述第三方面所述的多核苷酸、如上述第四方面所述的核酸构建体或如上述第五方面所述的表达载体。
第七方面，本申请提供了一种药物组合物，其包含如上述第一方面所述的多价纳米抗体、如上述第二方面所述的纳米抗体融合蛋白、如上述第三方面所述的多核苷酸、如上述第四方面所述的核酸构建体、如上述第五方面所述的表达载体或如上述第六方面所述的转化的细胞，以及药学上可接受的载体和/或赋形剂。
在具体实施方案中，所述药物组合物可以为鼻喷剂、口服制剂、栓剂或胃肠外制剂 的形式；
优选地，所述鼻喷剂选自气雾剂、喷雾剂和粉雾剂；
优选地，所述口服制剂选自片剂、粉末剂、丸剂、散剂、颗粒剂、细粒剂、软/硬胶囊剂、薄膜包衣剂、小丸剂、舌下片和膏剂；
优选地，所述胃肠外制剂为经皮剂、软膏剂、硬膏剂、外用液剂、可注射或可推注制剂。
本申请的药物组合物的有效成分的给药量，根据给药对象、对象脏器、症状、给药方法等不同而存在差异，可以考虑剂型的种类、给药方法、患者的年龄和体重、患者的症状等，根据医生的判断来确定。
第八方面，本申请提供了一种如上述第一方面所述的多价纳米抗体、如上述第二方面所述的纳米抗体融合蛋白、如上述第三方面所述的多核苷酸、如上述第四方面所述的核酸构建体、如上述第五方面所述的表达载体、如上述第六方面所述的转化的细胞或如上述第七方面所述的药物组合物在制备用于预防和/或治疗新型冠状病毒感染的药物中的应用。
在具体实施方案中，所述新型冠状病毒可以为SARS-CoV-2原始毒株和/或SARS-CoV-2变异毒株；
优选地，所述SARS-CoV-2变异毒株为Alpha(B.1.1.7)、Beta(B.1.351)、Gamma(P.1)、Kappa(B.1.617.1)、Delta(B.1.617.2)毒株、Omicron(B.1.1.529)亚型BA.1毒株或Omicron(B.1.1.529)亚型BA.2毒株；进一步优选地，所述SARS-CoV-2变异毒株为Delta(B.1.617.2)毒株、Omicron(B.1.1.529)亚型BA.1毒株或Omicron(B.1.1.529)亚型BA.2毒株。
第九方面，本申请提供了一种如上述第一方面所述的多价纳米抗体、如上述第二方面所述的纳米抗体融合蛋白、如上述第三方面所述的多核苷酸、如上述第四方面所述的核酸构建体、如上述第五方面所述的表达载体或如上述第六方面所述的转化的细胞在制备用于检测新型冠状病毒或用于诊断新型冠状病毒感染的试剂或试剂盒中的应用。
在具体实施方案中，所述新型冠状病毒可以为SARS-CoV-2原始毒株和/或SARS-CoV-2变异毒株；
优选地，所述SARS-CoV-2变异毒株为Alpha(B.1.1.7)、Beta(B.1.351)、Gamma(P.1)、Kappa(B.1.617.1)、Delta(B.1.617.2)毒株、Omicron(B.1.1.529)亚型BA.1毒株或Omicron(B.1.1.529)亚型BA.2毒株；进一步优选地，所述SARS-CoV-2变异毒株为Delta(B.1.617.2)毒株、Omicron(B.1.1.529)亚型BA.1毒株或Omicron(B.1.1.529)亚型BA.2毒株。
第十方面，本申请提供了一种新型冠状病毒检测试剂盒，其包括如上述第一方面所述的多价纳米抗体、如上述第二方面所述的纳米抗体融合蛋白、如上述第三方面所述的 多核苷酸、如上述第四方面所述的核酸构建体、如上述第五方面所述的表达载体或如上述第六方面所述的转化的细胞。
有益效果
本申请针对新冠病毒进行纳米抗体构建体的药物开发，本申请的基于纳米抗体S43的构建体均能以高亲和力与SARS-CoV-2 RBD结合，能以高中和活性中和SARS-CoV-2原型毒株和一系列变异毒株的假病毒和活病毒，这些均表明：基于纳米抗体S43的构建体是能够以高亲和力与SARS-CoV-2 RBD结合的、并具有高中和活性的新型冠状病毒(SARS-CoV-2)纳米抗体。
特别是，发明人通过一系列实验证明，本申请的基于纳米抗体S43的三价纳米抗体(TS43)和IgM五聚体形式(MS43)相对于其单体(即，纳米抗体S43)具有明显提高的中和活性和显著延长的半衰期，其实现了黏膜免疫，可以限制病毒的繁殖和进一步跨越黏膜屏障，控制了病毒的黏膜传播，为新型冠状病毒的临床预防、治疗提供了潜在的可雾化给药的抗体新药，并可实现新型冠状病毒的灵敏、可靠检测。
附图说明
一个或多个实施例通过与之对应的附图中的图片进行示例性说明，这些示例性说明并不构成对实施例的限定。在这里专用的词“示例性”意为“用作例子、实施例或说明性”。这里作为“示例性”所说明的任何实施例不必解释为优于或好于其它实施例。
图1是本申请实施例1中所构建的纳米抗体构建体TS43和MS43的结构示意图；
图2是本申请实施例1中所记载的S43蛋白分子筛层析和SDS-PAGE鉴定结果图；
图3是本申请实施例1中所记载的TS43蛋白分子筛层析和SDS-PAGE鉴定结果图；
图4是本申请实施例1中所记载的MS43蛋白分子筛层析和SDS-PAGE鉴定结果图；
图5是本申请实施例2中所记载的SARS-CoV-2 RBD-his蛋白(A)、变异毒株Omicron(B.1.1.529)亚型BA.1的RBD-his蛋白(B)和Omicron(B.1.1.529)亚型BA.2的RBD-his蛋白(C)的SDS-PAGE鉴定结果图。
图6是本申请实施例5中所测定的三种抗体中和SARS-CoV-2原型毒株假病毒感染的效果示意图。
图7是本申请实施例5中所测定的三种抗体中和SARS-CoV-2变异毒株Delta(B.1.617.2)假病毒感染的效果示意图。
图8是本申请实施例5中所测定的三种抗体中和SARS-CoV-2变异毒株Omicron(B.1.1.529)亚型BA.1假病毒感染的效果示意图。
图9是本申请实施例5中所测定的三种抗体中和SARS-CoV-2变异毒株Omicron(B.1.1.529)亚型BA.2假病毒感染的效果示意图。
图10是本申请实施例7中所测定的三种抗体在雾化前、后对假病毒的中和活性； 其中，A为纳米抗体S43在雾化前、后对SARS-CoV-2原型毒株假病毒的中和活性结果，B为纳米抗体构建体TS43对SARS-CoV-2原型毒株假病毒的中和活性结果，C为纳米抗体构建体MS43对SARS-CoV-2变异毒株Delta(B.1.617.2)假病毒的中和活性结果。
具体实施方式
为使本申请实施例的目的、技术方案和优点更加清楚，下面将对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。除非另有其它明确表示，否则在整个说明书和权利要求书中，术语“包括”或其变换如“包含”或“包括有”等等将被理解为包括所陈述的元件或组成部分，而并未排除其它元件或其它组成部分。
另外，为了更好的说明本申请，在下文的具体实施方式中给出了众多的具体细节。本领域技术人员应当理解，没有某些具体细节，本申请同样可以实施。在一些实施例中，对于本领域技术人员熟知的原料、元件、方法、手段等未作详细描述，以便于凸显本申请的主旨。
以下，对本申请进行详述。
定义
“纳米抗体”，即“重链单域抗体”，该类抗体只包含一个重链可变区(VHH，variable domain of heavy chain of heavy-chain antibody)，相比于其他抗体，轻链天然缺失。
由于纳米抗体自身的生物物理优势，可以很容易地对其进行雾化并通过吸入器直接递送到肺部，从而治疗呼吸系统病毒引起的感染，被认为是非常有潜力的抗体类药物。
当提及配体/受体、抗体/抗原或其它结合对时，“特异性”结合是指在蛋白和/或其它生物试剂的异质群体中确定是否存在所述蛋白例如本申请的纳米抗体与SARS-CoV-2RBD蛋白的结合反应。因此，在所指定的条件下，特定的配体/抗原与特定的受体/抗体结合，并且并不以显著量与样品中存在的其它蛋白结合。
本申请以下实施例中所使用的试剂、酶、培养基、抗生素和牛奶等化学材料均为市售产品，例如，TRIzol购自Invitrogen，Superscript II First-Strand Synthesis System for RT-PCR试剂盒购自Invitrogen。
一些常用的生物材料，如感受态细胞、载体、辅助噬菌体、待转化的细胞等也为市售产品，例如，pCAGGS载体购自MiaoLingPlasmid；293F细胞、HEK293T细胞等购自ATCC；Series Sensor Chip SA芯片购自GE Healthcare；Vero细胞购自ATCC CCL81。
一些合成类生物材料，例如引物、序列等需要人工合成的材料，均委托合成公司完成，例如，本申请中的TS43的编码序列由北京擎科生物科技有限公司合成。
实施例1：基于纳米抗体S43的三价形式(TS43)和IgM五聚体形式(MS43)抗体的构建、表达与纯化
本实施例中的单链纳米抗体及其三价形式和IgM五聚体形式的结构示意图如图1所示。
所采用的基础纳米抗体S43为本实验室通过用SARS-CoV-2S蛋白免疫羊驼、构建抗体文库、利用噬菌体展示技术进行筛选而得；单链纳米抗体S43的VHH链的氨基酸序列如SEQ ID NO:8所示，其能以高亲和力、特异性地结合SARS-CoV-2 RBD(结合常数为1.2E-10±1.4E-11M)，并且在假病毒中和实验中，能以高中和活性中和SARS-CoV-2假病毒，这些均表明：S43纳米抗体是能够以高亲和力与SARS-CoV-2 RBD结合的、并具有高中和活性的新型冠状病毒(SARS-CoV-2)羊驼源纳米抗体。
在上述单链纳米抗体S43VHH链的编码序列(如SEQ ID NO:14所示)的5’端连接信号肽(ATMHSSALLCCLVLLTGVRA，SEQ ID NO:15)、3’端连上6个组氨酸标签(hexa-His-tag)的编码序列及翻译终止密码子TGA，通过限制性内切酶位点EcoRI和XhoI，将其构建入pCAGGS载体(购自Invitrogen)中，然后将所得重组载体转染至293F细胞(购自Invitrogen)中，进行S43-his蛋白的表达。含有目的蛋白的细胞培养液经镍离子亲和层析(HisTrap TM excel((GE Healthcare))和凝胶过滤层析(SuperdexTM 75 Increase 10/300GL column(GE Healthcare))纯化后，可以获得较纯的目的蛋白。S43-his蛋白的SDS-PAGE鉴定大小为15KD左右，结果如图2所示。
通过两段(GGGGS)3序列，将三个如SEQ ID NO:14所示的纳米抗体S43VHH链的编码序列通过头尾相连形式串联(由北京擎科生物科技有限公司直接合成)，在其5’端连接信号肽(ATMHSSALLCCLVLLTGVRA，SEQ ID NO:15)、3’端连上6个组氨酸标签(hexa-His-tag)的编码序列及翻译终止密码子TGA，通过限制性内切酶位点EcoRI和XhoI，将其构建入pCAGGS载体(购自Invitrogen)中，然后将所得重组载体转染至293F细胞(购自Invitrogen)中，进行TS43-his蛋白的表达。含有目的蛋白的细胞培养液经镍离子亲和层析(HisTrap TM excel((GE Healthcare))和凝胶过滤层析(SuperdexTM 200 Increase 10/300GL column(GE Healthcare))纯化后，可以获得较纯的目的蛋白。TS43-his蛋白的SDS-PAGE鉴定大小为50KD左右，结果如图3所示。
通过同源重组的方式，将纳米抗体S43VHH链的编码序列(如SEQ ID NO:14所示)与人源IgM抗体的Fc的编码序列(如SEQ ID NO:16所示)连接，在其5’端连接信号肽(ATMHSSALLCCLVLLTGVRA，SEQ ID NO:15)、3’端连上翻译终止密码子TGA，通过限制性内切酶位点EcoRI和XhoI，将其构建入pCAGGS载体(购自Invitrogen)，获得pCAGGS-S43-IgM Fc重组表达载体。将J链(Joining chain)的编码序列(如SEQ ID NO:17 所示)的3’端连上翻译终止密码子TGA，通过限制性内切酶位点EcoRI和XhoI，将其构建入pCAGGS载体(购自Invitrogen)，获得pCAGGS-J chain重组表达载体。将上述两种重组表达载体pCAGGS-S43-IgM Fc与pCAGGS-J chain共转染至293F细胞(购自Invitrogen)中，进行S43-IgM Fc融合蛋白和J链的表达，二者再进行自组装，形成IgM形式的MS43蛋白。所得MS43蛋白通过HiTrapTMIgM Purification HP(GE Healthcare)和SuperoseTM6 increase 10/300GL(GE Healthcare)纯化，再经SDS-PAGE进行鉴定。MS43蛋白的SDS-PAGE鉴定大小为70KD左右，结果如图4所示。
实施例2：SARS-CoV-2及其变异毒株RBD的表达与纯化
在SARS-CoV-2原始毒株的RBD蛋白(其氨基酸序列如SEQ ID NO:18所示)的编码序列的3’端连上6个组氨酸标签(hexa-His-tag)的编码序列及翻译终止密码子TGA，通过限制性内切酶位点EcoRI和XhoI，将其构建入pCAGGS载体(购自Invitrogen)中，然后将所得重组载体转染至293F细胞(购自Invitrogen)中，进行SARS-CoV-2 RBD-his蛋白的表达。
分别在SARS-CoV-2变异毒株Omicron(B.1.1.529)亚型BA.1的RBD蛋白(其氨基酸序列如SEQ ID NO:19所示)的编码序列和Omicron(B.1.1.529)亚型BA.2的RBD蛋白(其氨基酸序列如SEQ ID NO:20所示)的编码序列的3’端分别连上6个组氨酸标签(hexa-His-tag)的编码序列及翻译终止密码子TGA，通过bac-to-bac杆状病毒表达系统(Invitrogen)进行表达。将含有目的基因的pFastbac1质粒转化至DH10Bac感受态细胞中,生成重组杆粒(bacmids)。将重组杆粒bacmids转染至Sf9细胞中进行病毒的扩增,并在Hi5细胞中进行蛋白表达。表达48h后,收集Hi5细胞上清液,使用HisTrap TM excel(GE Healthcare)通过镍亲和层析纯化可溶性蛋白。
含有目的蛋白的细胞培养液经镍离子亲和层析柱HisTrap TM excel(GE Healthcare)和凝胶过滤层析SuperdexTM 200 Increase 10/300GL column(GE Healthcare)纯化后，可以获得较纯的目的蛋白。SARS-CoV-2 RBD-his蛋白、变异毒株Omicron(B.1.1.529)亚型BA.1的RBD-his蛋白和Omicron(B.1.1.529)亚型BA.2的RBD-his蛋白的SDS-PAGE鉴定大小为30KD左右，分别如图5A～C所示。
实施例3：表面等离子共振技术检测各抗体与SARS-CoV-2原始毒株及其变异株的RBD蛋白的结合能力
表面等离子共振分析利用Biacore 8K(Biacore Inc.)进行。具体步骤如下：
分别将上述实施例所制备的单链纳米抗体S43及其构建体TS43和MS43进行生物素化，然后固定到Series Sensor Chip SA芯片(Cytiva Life Sciences)上；用PBST缓冲液(2.7mM KCl，137mM NaCl，4.3mM Na2HPO4，1.4mM KH2PO4，0.05％吐温)分别将上述 实施例所制备的SARS-CoV-2原始毒株及其变异株的RBD蛋白进行倍比稀释，从低浓度到高浓度逐一上样至芯片。结合动力学常数的计算是利用BIAevaluation software 8K(Biacore，Inc.)软件进行的。各抗体与各RBD之间的平衡解离常数(KD)如表1所示，表1结果表明：单链纳米抗体S43及其构建体TS43和MS43都能够和SARS-CoV-2原型毒株及变异毒株Omicron亚型BA.1、Omicron亚型BA.2的RBD蛋白以较高的亲和力结合。
表1、单链纳米抗体S43及其构建体TS43和MS43与SARS-CoV-2原始毒株及变异毒株的RBD之间的亲和性结果
实施例4：SARS-CoV-2原始毒株及变异毒株假病毒的包装
1)分别将编码SARS-CoV-2原始毒株(WT)及变异毒株Delta(B.1.617.2)、Omicron(B.1.1.529)亚型BA.1和Omicron(B.1.1.529)亚型BA.2的S蛋白后18位氨基酸的基因去掉，S蛋白其余序列进行合成(由苏州金唯智提供合成服务)，得到SARS-CoV-2-WT-S-del18、B.1.617.2-S-del18、B.1.1.529-BA.1-S-del18和B.1.1.529-BA.2-S-del18基因的核苷酸序列，序列分别如SEQ ID NO:21～24所示。
2)分别将1)中获得的该蛋白基因克隆到pCAGGS载体上，得到表达质粒pCAGGS-SARS-CoV-2-WT-S-del18、pCAGGS-B.1.617.2-S-del18、pCAGGS-B.1.1.529-BA.1-S-del18和pCAGGS-B.1.1.529-BA.2-S-del18。
SARS-CoV-2原始毒株及变异毒株假病毒的包装步骤如下：
a.细胞准备：在10cm细胞培养皿中铺HEK293T细胞(购自ATCC CRL-3216)，使第二天细胞汇合密度至80％左右。培养液为含10％FBS的DMEM培养基。
b.转染：取上述步骤2)中的各S蛋白的表达质粒，用PEI转染30μg质粒/10cm细胞培养皿，目的质粒与PEI按1:3比例混匀后转染，4-6h换培养液(含10％FBS的DMEM培养基)，37℃培养24h。
c.加毒：将假病毒包装骨架病毒G*VSV-delG(购自武汉枢密脑科学技术有限公司)加入上述转染后的HEK293T细胞，37℃孵育2h，换培养液(含10％FBS的DMEM培养基)，并加入VSV-G抗体(表达该抗体的杂交瘤细胞购自ATCC细胞库)，在培养箱中继续培养30h。
d.收毒：收上清3000rpm离心10min,在超净工作台中经0.45μm无菌滤器过滤， 去除细胞碎片，分装，-80℃冰箱冻存。
分别得到SARS-CoV-2原型毒株(SARS-CoV-2WT)及变异毒株Delta(B.1.617.2)、Omicron(B.1.1.529)亚型BA.1、Omicron(B.1.1.529)亚型BA.2的假病毒。
实施例5：抗体中和假病毒感染的检测
将经纯化的单链纳米抗体S43及其构建体TS43和MS43(由实施例1制得)分别以5倍倍比稀释至第9个梯度(2.56pg/mL)，将稀释液与1.6×104TCID50实施例4获得的一系列SARS-CoV-2原始毒株及变异毒株的假病毒分别混合，在37℃混合孵育1h，然后加入到预先接种Vero细胞(购自ATCC CCL81)的96孔板中。孵育18～20小时后，通过CQ1Confocal Quantitative Image Cytometer(Yokogawa)检测。根据带GFP荧光的细胞数，计算抗体对上述一系列SARS-CoV-2原型毒株及变异毒株Delta、BA.1和BA.2的假病毒的中和能力，其结果分别如图6～9所示，结果统计如表2；结果显示，相对于单链纳米抗体S43，其构建体TS43和MS43的假病毒中和效果均得以提高。
表2、单链纳米抗体S43及其构建体TS43和MS43对SARS-CoV-2原始毒株及变异毒株的假病毒的中和能力
注：IC50(μg/mL)为抗体的半抑制浓度。*表示最高浓度10mg/mL时测定仍未达到100％抑制率。
实施例6：抗体中和活病毒感染的检测
本实施例中，通过基于细胞病变效应(CPE)的活病毒中和试验，测定各抗体对新冠病毒活病毒的中和效果。具体步骤如下：
将经纯化的单链纳米抗体S43及其TS43和MS43(由实施例1制得)分别以2倍倍比稀释至第11个梯度，每个梯度4个重复孔，每孔50μL，将稀释液与等体积的100TCID50的SARS-CoV-2原始毒株或其变异毒株Delta、Omicron亚型BA.1于37℃孵育。1小时后，将混合物加入到悬浮的Vero细胞中，并在37℃下继续孵育3天。观察和记录细胞病变情况。使用GraphPad Prism 7.0计算纳米抗体及其构建体的IC50。实验均在中国疾病预防控制中心的生物安全三级实验室(BSL3)中进行。
单链纳米抗体S43及其TS43和MS43对新冠病毒原始毒株及其变异毒株的活病毒中和效果见表3，表3结果显示：TS43和MS43对新冠病毒原始毒株及变异毒株的活病毒均具有良好的抑制效果。
表3、单链纳米抗体S43及其构建体TS43和MS43对SARS-CoV-2原始毒株及变异毒株的活病毒的中和能力
注：IC50(μg/mL)为抗体的半抑制浓度。
实施例7：抗体雾化前后稳定性的检测
使用Aerogen Solo(Aerogen Inc.,Chicago,USA)雾化器，分别将单链纳米抗体S43及其构建体TS43和MS43进行雾化，然后使用含有20mL PBS的全玻璃SKC(Eighty Four,PA,USA)收集雾化后的抗体，并按实施例5所述进行假病毒中和试验。结果如图10所示，其中，A为纳米抗体S43在雾化前、后对SARS-CoV-2原型毒株假病毒的中和活性结果，B为纳米抗体构建体TS43对SARS-CoV-2原型毒株假病毒的中和活性结果，C为纳米抗体构建体MS43对SARS-CoV-2变异毒株Delta(B.1.617.2)假病毒的中和活性结果；图10结果表明：本申请的纳米抗体构建体TS43和MS43在雾化前、后对新冠病毒原型毒株或其变异毒株的假病毒的中和活性保持稳定，提示它们均适于通过雾化途径给药。
上述结果表明，本申请的基于纳米抗体S43的构建体TS43和MS43具有开发成为治疗新型冠状病毒及其变异毒株感染的高中和活性抗体药物、特别是雾化药物的潜力。
最后应说明的是：以上实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的精神和范围。
工业实用性
本申请的基于特异性结合SARS-CoV-2 RBD的纳米抗体S43的构建体能有效抑制SARS-CoV-2感染及其变异毒株感染，可以雾化给药，能直达肺部，起效较快，且半衰期长，为临床上预防或治疗新冠病毒及其变异株感染提供了更有效的治疗选择。

Claims (17)

  1. 一种多价纳米抗体，其包括两条以上、特异性结合SARS-CoV-2 RBD的纳米抗体的VHH链，其中，所述特异性结合SARS-CoV-2 RBD的纳米抗体的VHH链包括以下CDR：氨基酸序列如SEQ ID NO:1所示的CDR1，氨基酸序列如SEQ ID NO:2所示的CDR2，以及氨基酸序列如SEQ ID NO:3所示的CDR3。
  2. 根据权利要求1所述的多价纳米抗体，其特征在于，所述特异性结合SARS-CoV-2RBD的纳米抗体的VHH链还包括4个框架区FR1-4，所述FR1-4与所述CDR1、CDR2和CDR3按顺序交错排列；
    优选地，所述FR1-4的氨基酸序列分别如SEQ ID NO:4、5、6、7所示。
  3. 根据权利要求1所述的多价纳米抗体，其特征在于，所述特异性结合SARS-CoV-2RBD的纳米抗体的VHH链具有如SEQ ID NO:8所示的氨基酸序列，或与SEQ ID NO:8所示的氨基酸序列具有至少95％，96％，97％，98％或99％序列同一性的氨基酸序列。
  4. 根据权利要求1-3任一项所述的多价纳米抗体，其由两条以上、优选地三条所述特异性结合SARS-CoV-2 RBD的纳米抗体的VHH链通过Linker连接构成；
    其中，所述Linker为(GGGGS)n，其中，n＝1,2,3,或4，优选地，n＝2或3；
    优选地，所述多价纳米抗体为三价纳米抗体，具有如SEQ ID NO:9所示的氨基酸序列。
  5. 根据权利要求1-3任一项所述的多价纳米抗体，其特征在于，所述多价纳米抗体为由以下融合蛋白形成的IgM五聚体，所述融合蛋白从N端到C端的结构如式(I)所示：
    A-L-B   (I)
    其中，
    A为单条、所述特异性结合SARS-CoV-2 RBD的纳米抗体的VHH链，或者为根据权利要求4所述的多价纳米抗体；
    B为人源IgM的Fc片段；优选地，所述人源IgM的Fc片段具有如SEQ ID NO:10所示的氨基酸序列，或与SEQ ID NO:10所示的氨基酸序列具有至少95％，96％，97％，98％或99％序列同一性的氨基酸序列；
    L为(GGGGS)m，其中，m＝0,1,2,3,或4；
    优选地，所述融合蛋白具有如SEQ ID NO:11所示的氨基酸序列。
  6. 一种纳米抗体融合蛋白，其特征在于，所述纳米抗体融合蛋白从N端到C端的结构如式(I)所示：
    A-L-B   (I)
    其中，
    A为单条、特异性结合SARS-CoV-2 RBD的纳米抗体的VHH链，所述特异性结合SARS-CoV-2 RBD的纳米抗体的VHH链如权利要求1-3任一项中所定义，或者A为根据权利要求4所述的多价纳米抗体；
    B为人源IgM的Fc片段；优选地，所述人源IgM的Fc片段具有如SEQ ID NO:9所示的氨基酸序列，或与SEQ ID NO:9所示的氨基酸序列具有至少95％，96％，97％，98％或99％序列同一性的氨基酸序列；
    L为(GGGGS)m，其中，m＝0,1,2,3,或4；
    优选地，所述融合蛋白具有如SEQ ID NO:11所示的氨基酸序列。
  7. 一种多核苷酸，其编码如权利要求1至5任一项所述的多价纳米抗体，或者编码如权利要求6所述的纳米抗体融合蛋白。
  8. 根据权利要求7所述的多核苷酸，其特征在于，所述多核苷酸为DNA或mRNA；
    优选地，所述多核苷酸编码如权利要求4所述的多价纳米抗体，进一步优选地，所述多核苷酸包括如SEQ ID NO:12所示的核苷酸序列；
    优选地，所述多核苷酸编码如权利要求6所述的纳米抗体融合蛋白，进一步优选地，所述多核苷酸包括如SEQ ID NO:13所示的核苷酸序列。
  9. 一种核酸构建体，其包含如权利要求7或8所述的多核苷酸，以及任选地，与所述多核苷酸可操作地连接的至少一个表达调控元件。
  10. 一种表达载体，其包含如权利要求9所述的核酸构建体。
  11. 一种转化的细胞，其包括如权利要求7或8所述的多核苷酸、如权利要求9所述的核酸构建体或如权利要求10所述的表达载体。
  12. 一种药物组合物，其包含如权利要求1至5任一项所述的多价纳米抗体、如权利要求6所述的纳米抗体融合蛋白、如权利要求7或8所述的多核苷酸、如权利要求9所述的核酸构建体、如权利要求10所述的表达载体或如权利要求11所述的转化的细胞，以及药学上可接受的载体和/或赋形剂。
  13. 根据权利要求12所述的药物组合物，其特征在于，所述药物组合物为鼻喷剂、口服制剂、栓剂或胃肠外制剂的形式；
    优选地，所述鼻喷剂选自气雾剂、喷雾剂和粉雾剂；
    优选地，所述口服制剂选自片剂、粉末剂、丸剂、散剂、颗粒剂、细粒剂、软/硬胶囊剂、薄膜包衣剂、小丸剂、舌下片和膏剂；
    优选地，所述胃肠外制剂为经皮剂、软膏剂、硬膏剂、外用液剂、可注射或可推注 制剂。
  14. 如权利要求1至5任一项所述的多价纳米抗体、如权利要求6所述的纳米抗体融合蛋白、如权利要求7或8所述的多核苷酸、如权利要求9所述的核酸构建体、如权利要求10所述的表达载体、如权利要求11所述的转化的细胞或如权利要求12或13所述的药物组合物在制备用于预防和/或治疗新型冠状病毒感染的药物中的应用。
  15. 如权利要求1至5任一项所述的多价纳米抗体、如权利要求6所述的纳米抗体融合蛋白、如权利要求7或8所述的多核苷酸、如权利要求9所述的核酸构建体、如权利要求10所述的表达载体或如权利要求11所述的转化的细胞在制备用于检测新型冠状病毒或用于诊断新型冠状病毒感染的试剂或试剂盒中的应用。
  16. 根据权利要求14或15所述的应用，其特征在于，所述新型冠状病毒为SARS-CoV-2原始毒株和/或SARS-CoV-2变异毒株；
    优选地，所述SARS-CoV-2变异毒株为Alpha(B.1.1.7)、Beta(B.1.351)、Gamma(P.1)、Kappa(B.1.617.1)、Delta(B.1.617.2)毒株、Omicron(B.1.1.529)亚型BA.1毒株或Omicron(B.1.1.529)亚型BA.2毒株，进一步优选为Delta(B.1.617.2)毒株、Omicron(B.1.1.529)亚型BA.1毒株或Omicron(B.1.1.529)亚型BA.2毒株。
  17. 一种新型冠状病毒检测试剂盒，其包括如权利要求1至5任一项所述的多价纳米抗体、如权利要求6所述的纳米抗体融合蛋白、如权利要求7或8所述的多核苷酸、如权利要求9所述的核酸构建体、如权利要求10所述的表达载体或如权利要求11所述的转化的细胞。
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