WO2022037531A1 - 抗cd73的抗体及其用途 - Google Patents

抗cd73的抗体及其用途 Download PDF

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WO2022037531A1
WO2022037531A1 PCT/CN2021/112771 CN2021112771W WO2022037531A1 WO 2022037531 A1 WO2022037531 A1 WO 2022037531A1 CN 2021112771 W CN2021112771 W CN 2021112771W WO 2022037531 A1 WO2022037531 A1 WO 2022037531A1
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antibody
seq
amino acid
antigen
sequence
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PCT/CN2021/112771
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French (fr)
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王忠民
金小平
李百勇
夏瑜
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中山康方生物医药有限公司
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Priority to JP2023511960A priority Critical patent/JP2023538369A/ja
Priority to AU2021326889A priority patent/AU2021326889A1/en
Priority to CA3191745A priority patent/CA3191745A1/en
Priority to EP21857625.4A priority patent/EP4197555A1/en
Publication of WO2022037531A1 publication Critical patent/WO2022037531A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K16/00—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies
    • C07K16/18—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans
    • C07K16/28—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants
    • C07K16/2896—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants against molecules with a "CD"-designation, not provided for elsewhere
    • 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
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K16/00—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies
    • C07K16/40—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against enzymes
    • 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
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/20—Immunoglobulins specific features characterized by taxonomic origin
    • C07K2317/24—Immunoglobulins specific features characterized by taxonomic origin containing regions, domains or residues from different species, e.g. chimeric, humanized or veneered
    • 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
    • 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
    • C07K2317/70—Immunoglobulins specific features characterized by effect upon binding to a cell or to an antigen
    • C07K2317/74—Inducing cell proliferation
    • 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
    • C07K2317/70—Immunoglobulins specific features characterized by effect upon binding to a cell or to an antigen
    • C07K2317/77—Internalization into the cell
    • 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

Definitions

  • the present invention relates to the field of immunology.
  • it relates to anti-CD73 antibodies and uses thereof.
  • Ecto-5'-nucleotidase namely CD73 protein
  • CD73 protein is a multifunctional glycoprotein with a molecular weight of 70KD encoded by the NT5E gene.
  • phosphatidy linositol, GPI is anchored to the cell membrane (Zimmermann H. Biochem J. 1992;285:345-365).
  • CD73 is widely distributed on the surface of human tissue cells and is also widely expressed on the surface of immune cells, such as dendritic cells, regulatory T cells (Treg), natural killer cells (NK cells), and myeloid-derived suppressor cells (MDSC).
  • immune cells such as dendritic cells, regulatory T cells (Treg), natural killer cells (NK cells), and myeloid-derived suppressor cells (MDSC).
  • CD73 has both hydrolase activity and non-hydrolase activity.
  • One of the immunosuppressive mechanisms of the enzymatic and non-enzymatic functions of CD73 is mediated by the CD73-Adenosine metabolic signaling pathway.
  • CD39 upstream of CD73 can catalyze the production of adenosine monophosphate (AMP) from ATP, and the generated AMP is catalyzed by CD73 It is converted into adenosine, and adenosine binds to the downstream adenosine receptor (A2AR).
  • A2AR inhibits a series of immune activation-related signaling pathways such as LCK, MAPK, and PKC by activating protein kinase A (PKA) and Csk kinase. Inhibit the immune killing effect of T cells, thereby exerting an immunosuppressive effect (Antonioli L, et al. Nat Rev Cancer. 2013; 13: 842-857.).
  • PKA protein kinase A
  • Coronaviruses include 2019 novel coronavirus (2019-nCoV or SARS-CoV-2, which causes novel coronavirus pneumonia COVID-19), HCoV-229E, HCoV-OC43, HCoV-NL63, HCoV-HKU1, SARS-CoV ( cause severe acute respiratory syndrome) and MERS-CoV (causes Middle East respiratory syndrome). Infection with the above-mentioned viruses can lead to severe clinical symptoms and even life-threatening.
  • SARS-CoV fights immune responses through different mechanisms.
  • One such mechanism is through the inhibition of type 1 interferon (IFN-1) expression and signaling (Kindler, E., Thiel et al. SARS-CoV and IFN: Too Little, Too Late. Cell Host Microbe 2016, 19 ( 2), 139-141.).
  • IFN-1 type 1 interferon
  • IFN-1 inducible type I interferons play a key role in the antiviral immune response by inducing cell resistance to viral infection and promoting apoptosis in virus-infected cells.
  • SARS-CoV hinders the rapid increase of IFN-I, which promotes the replication of coronaviruses.
  • SARS-CoV-2 expresses a variety of proteins that inhibit interferon (Konno, Yoriyuki, et al.
  • SARS-CoV-2 ORF3b is a potent interferon antagonist whose activity is further increased by a naturally occurring elongation variant.bioRxiv ( 2020). Yuen, Chun-Kit, et al. SARS-CoV-2 nsp13, nsp14, nsp15 and orf6 function as potent interferon antagonists. Emerging Microbes and Infections (2020): 1-29.), thus demonstrating that this inhibition is effective Key mechanisms of early immune responses.
  • Inhibition of the ATP degradation pathway can be used as a mechanism for the treatment of COVID-19, and ATP stimulates the secretion of interferon, which may counteract the powerful interferon inhibitory mechanism of SARS-CoV-2. If successful, this will help eliminate the virus in the early stages of infection.
  • hypoxia hypoxia-inducible factor-1
  • CD73 Hypoxia-inducible factor-1
  • A2B receptors are more easily activated under hypoxia, and the activation of A2BR directly promotes the production of a large amount of IL-6 in related cells, which not only induces the differentiation of lung fibroblasts (Hongyan Zhong, Luiz Belardinelli et al.
  • IL-6 is one of the key inflammatory factors that trigger cytokine storm in patients with new coronary pneumonia one. Therefore, reducing adenosine levels may be particularly beneficial for patients with CRS and respiratory distress.
  • SARS-CoV severe acute respiratory syndrome coronavirus
  • Boosting the immune response may lead to faster viral clearance, shorter recovery times, fewer complications, longer immunity and protection against reinfection.
  • the ability to boost the immune response offers a potential opportunity to treat COVID-19 and other epidemics.
  • CD73 is expressed in human B cells, T cells, bone marrow cells, bone marrow stromal cells and thymic epithelial cells. Studies have shown (Giovanni Forte, Rosalinda Sorrentino et al. Inhibition of CD73 Improvements B Cell-Mediated Anti-T ⁇ Mor Immunity in a Mouse Model of Melanoma. The Journal of Immunology, 2012, 189: 2226-2233.), antagonism of CD73 can be achieved by IL-17A affects the activity of B cells to produce IgG, a major component of antibacterial, antitoxin and antiviral antibodies.
  • blocking CD73 may be used to treat diseases caused by coronaviruses including COVID-19 by modulating the CD73 adenosine pathway and affecting the immune response.
  • the present inventors use a mammalian cell expression system to express recombinant human CD73 as an antigen to immunize mice, and obtain hybridoma cells by fusing mouse spleen cells with myeloma cells.
  • the inventors obtained the hybridoma cell line LT014 by screening a large number of samples (the deposit number is CCTCC NO: C2018137).
  • the inventors have surprisingly found that the hybridoma cell line LT014 can secrete and produce a specific monoclonal antibody (named 19F3) that specifically binds to human CD73, and further, the inventors have prepared a humanized antibody against human CD73 (designated 19F3H2L3).
  • the inventors also surprisingly found that the antibody 19F3H2L3 of the present invention can very effectively inhibit the enzymatic reaction of CD73 in a non-substrate competition manner, reduce the production of adenosine, promote the endocytosis of CD73 on the cell membrane surface, and stimulate the activation of B cells and proliferation.
  • the antibody of the present invention has the effect of treating related diseases caused by coronavirus infection.
  • anti-CD73 eg, human CD73
  • antigen-binding fragment thereof for use in the treatment and/or prevention of infection caused by a coronavirus, wherein the anti-CD73 antibody comprises:
  • the anti-CD73 antibody comprises HCDR1, HCDR2 and HCDR3 contained in the heavy chain variable region shown in SEQ ID NO: 2, SEQ ID NO: 6 or SEQ ID NO: 10, and SEQ ID NO: 4, SEQ ID NO: : 8.
  • the anti-CD73 antibody comprises: HCDR1, which comprises the amino acid sequence shown in SEQ ID NO: 15, having at least 80%, 81%, 82%, 83%, 84% with the sequence , 85%, 86%, 87%, 88%, 89%, 90%, preferably at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity , or an amino acid sequence having one or more (preferably 1, 2 or 3) conservative amino acid mutations (preferably substitutions, insertions or deletions) compared to said sequence, or consisting of,
  • HCDR2 comprising the amino acid sequence shown in SEQ ID NO: 16, having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89% with the sequence , 90%, preferably at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, or have one or more sequences compared to said sequence (preferably 1, 2 or 3) amino acid sequences of conservative amino acid mutations (preferably substitutions, insertions or deletions), or consisting of,
  • HCDR3 comprising the amino acid sequence shown in SEQ ID NO: 17, having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89% with the sequence , 90%, preferably at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, or have one or more sequences compared to said sequence (preferably 1, 2 or 3) amino acid sequences of conservative amino acid mutations (preferably substitutions, insertions or deletions), or consisting of,
  • LCDR1 comprising the amino acid sequence shown in SEQ ID NO: 18, having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89% with said sequence , 90%, preferably at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, or have one or more sequences compared to said sequence (preferably 1, 2 or 3) amino acid sequences of conservative amino acid mutations (preferably substitutions, insertions or deletions), or consisting of,
  • LCDR2 comprising the amino acid sequence shown in SEQ ID NO: 19, having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89% with said sequence , 90%, preferably at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, or have one or more sequences compared to said sequence (preferably 1, 2 or 3) the amino acid sequence of conservative amino acid mutations (preferably substitutions, insertions or deletions), or consisting of, and
  • LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 20, having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89% with said sequence , 90%, preferably at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity, or have one or more sequences compared to said sequence
  • the amino acid sequence of preferably 1, 2 or 3 conservative amino acid mutations (preferably substitutions, insertions or deletions), or consisting of.
  • the heavy chain variable region of the antibody comprises or consists of the following sequences:
  • SEQ ID NO:2, SEQ ID NO:6 or SEQ ID NO:10, and SEQ ID NO:2, SEQ ID NO:6 or SEQ ID NO:10 have at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity
  • the sequence of SEQ ID NO: 2, SEQ ID NO: 6 or SEQ ID NO: 10 has one or more (preferably 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10) amino acid sequences of conservative amino acid mutations (preferably substitutions, insertions or deletions); and
  • the light chain variable region of the antibody comprises or consists of the following sequences:
  • SEQ ID NO: 4 SEQ ID NO: 8, SEQ ID NO: 12, or SEQ ID NO: 14, and SEQ ID NO: 4, SEQ ID NO: 8, SEQ ID NO: 12, or SEQ ID NO: 14 having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96% , 97%, 98% or 99% sequence identity, or compared to the amino acid sequence set forth in SEQ ID NO: 4, SEQ ID NO: 8, SEQ ID NO: 12 or SEQ ID NO: 14 having one or more Amino acid sequence of multiple (preferably 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10) conservative amino acid mutations (preferably substitutions, insertions or deletions).
  • amino acid sequence of the heavy chain variable region of the antibody is set forth in SEQ ID NO:2
  • amino acid sequence of the light chain variable region of the antibody is set forth in SEQ ID NO:4 Show;
  • amino acid sequence of the variable region of the heavy chain of the antibody is shown in SEQ ID NO: 6, and the amino acid sequence of the variable region of the light chain of the antibody is shown in SEQ ID NO: 8;
  • amino acid sequence of the variable region of the heavy chain of the antibody is shown in SEQ ID NO: 10
  • amino acid sequence of the variable region of the light chain of the antibody is shown in SEQ ID NO: 12; or
  • amino acid sequence of the heavy chain variable region of the antibody is shown in SEQ ID NO: 10
  • amino acid sequence of the light chain variable region of the antibody is shown in SEQ ID NO: 14.
  • the heavy chain constant region of the antibody is the Ig gamma-1 chain C region, ACCESSION: P01857; the light chain constant region is the Ig kappa chain C region, ACCESSION: P01834.
  • variable regions of light and heavy chains determine antigen binding; the variable regions of each chain contain three hypervariable regions, called complementarity determining regions (CDRs) (the CDRs of the heavy chain (H) include HCDR1, HCDR2, HCDR3 , the CDRs of the light chain (L) comprise LCDR1, LCDR2, LCDR3; it is named by Kabat et al., see Bethesda Md, Sequences of Proteins of Immunological Interest, Fifth Edition, NIH Publication 1991; 1-3: 91-3242.
  • CDRs complementarity determining regions
  • the CDRs can also be defined by the IMGT numbering system, see Ehrenmann, Francois, Quentin Kaas, and Marie-Paule Lefranc.
  • IMGT/3Dstructure-DB and IMGT/DomainGapAlign a database and a tool for immunoglobulins or antibodies, T cell receptors , MHC, IgSF and MhcSF. Nucleic acids research 2009;38(suppl_1):D301-D307.
  • amino acid sequences of the CDR regions of the monoclonal antibody sequences are analyzed according to the IMGT definitions by technical means well known to those skilled in the art, for example, by the VBASE2 database.
  • antibody CDR regions Given the known sequences of antibody heavy and light chain variable regions, there are currently several methods for determining antibody CDR regions, including the Kabat, IMGT, Chothia and AbM numbering systems.
  • variable region amino acid sequence of the antibody Given the variable region amino acid sequence of the antibody, one skilled in the art can generally determine which residues comprise a particular CDR, without relying on any experimental data other than the sequence itself.
  • the antibodies 19F3, 19F3H1L1, 19F3H2L2 and 19F3H2L3 involved in the present invention have the same CDRs:
  • amino acid sequences of the three CDR regions in the variable region of its heavy chain are as follows:
  • HCDR1 GYSFTGYT (SEQ ID NO: 15),
  • HCDR2 INPYNAGT (SEQ ID NO: 16),
  • HCDR3 ARSEYRYGGDYFDY (SEQ ID NO: 17);
  • amino acid sequences of the three CDR regions of the light chain variable region are as follows:
  • LCDR1 QSLLNSSNQKNY (SEQ ID NO: 18),
  • LCDR2 FAS (SEQ ID NO: 19),
  • LCDR3 QQHYDTPYT (SEQ ID NO: 20).
  • the antibody is a monoclonal antibody.
  • the antibody is a humanized antibody, a chimeric antibody, a multispecific antibody (eg, a bispecific antibody), preferably, the heavy chain amino acid sequence of the anti-CD73 antibody is as shown in SEQ ID NO. : 23, the light chain amino acid sequence is shown in SEQ ID NO: 24.
  • the antigen-binding fragment is selected from the group consisting of Fab, Fab', F(ab') 2 , Fd, Fv, dAb, Fab/c, complementarity determining region fragments, single chain antibodies (eg, scFv ), humanized antibodies, chimeric antibodies or bispecific antibodies.
  • Yet another aspect of the present invention relates to a conjugate for treating and/or preventing infection caused by coronavirus, comprising an antibody and a conjugate moiety, wherein the antibody is the anti-CD73 according to any one of the present inventions Antibody or antigen-binding fragment thereof, the coupling part is a purification tag (such as His tag), a detectable label or a small molecule drug; preferably, the coupling part is a radioisotope, fluorescent substance, chemiluminescent substance, colored substance, polyethylene glycol or enzyme; preferably, the small molecule drug is a small molecule cytotoxic drug; more preferably, the small molecule drug is a tumor chemotherapy drug, more preferably, the antibody or its antigen-binding fragment
  • the linker is linked to the small molecule drug; for example, the linker is a hydrazone bond, a disulfide bond or a peptide bond; more preferably, the antibody or its antigen-binding fragment is linked to the small molecule drug at
  • Another aspect of the present invention relates to a fusion protein or a multispecific antibody (preferably a bispecific antibody) for the treatment and/or prevention of infection caused by coronavirus, comprising the anti-CD73 antibody according to any one of the present invention or its antigen-binding fragment.
  • a fusion protein or a multispecific antibody preferably a bispecific antibody
  • kits for treating and/or preventing infection caused by coronavirus comprising an effective amount (eg, 0.001 mg-1000 mg) of the anti-CD73 antibody or antigen-binding fragment thereof of the present invention , a conjugate, fusion protein or multispecific antibody of the invention, and optionally, further comprising an effective amount of one or more antiviral drugs (eg, 100-2400 mg).
  • kits for treating and/or preventing infection caused by coronavirus comprising the anti-CD73 antibody or its antigen-binding fragment, conjugate, fusion protein or Multispecific antibodies, and antigens for use as vaccines selected from among those derived from viruses, bacteria, fungi, rickettsia, chlamydia, mycoplasma, parasites, prions, or tumors.
  • Another aspect of the present invention relates to a pharmaceutical composition for treating and/or preventing infection caused by coronavirus, which comprises the anti-CD73 antibody or antigen-binding fragment thereof described in any one of the present invention, the conjugate of the present invention compound, fusion protein or multispecific antibody; optionally, the pharmaceutical composition further includes a pharmaceutically acceptable carrier and/or excipient.
  • the pharmaceutical composition is in a form suitable for administration by subcutaneous injection, intradermal injection, intravenous injection, intramuscular injection or intralesional injection.
  • Another aspect of the present invention relates to the antibody or antigen-binding fragment thereof, the conjugate or the fusion protein or the multispecific antibody for the treatment and/or prevention of infection caused by coronavirus according to the present invention,
  • the coronavirus is selected from novel coronaviruses SARS-CoV-2, HCoV-229E, HCoV-OC43, HCoV-NL63, HCoV - HKU1, SARS-CoV and/or MERS-CoV.
  • Yet another aspect of the present invention relates to a method of treating and/or preventing coronavirus infection, comprising administering to a subject or patient an effective amount of said anti-CD73 antibody or antigen-binding fragment thereof, said conjugate or said The fusion protein or multispecific antibody of or MERS-CoV.
  • the method comprises concurrently or sequentially administering to the subject or patient an antiviral drug (eg, favipiravir), preferably the antiviral drug is an RNA virus inhibitor.
  • an antiviral drug eg, favipiravir
  • the effective amount of the anti-CD73 antibody or antigen-binding fragment thereof, the antibody drug conjugate or the bispecific antibody of the present invention is 0.001 mg-1000 mg, more preferably 0.001 mg-900 mg, 0.001mg-800mg, 0.001mg-700mg, 0.001mg-600mg, 0.001mg-500mg, 0.001mg-400mg, 0.001mg-300mg, 0.001mg-200mg, 0.001mg-100mg, most preferably 100mg, 200mg, 300mg, 400mg , 500 mg, 600 mg, 700 mg, 800 mg, 900 mg or 1000 mg, or, based on the subject or patient's body weight, the effective amount is 0.1-100 mg/kg, preferably 1-90 mg/kg, 1-80 mg/kg, 1- 70 mg/kg, 1-60 mg/kg, 1-50 mg/kg, 1-40 mg/kg, 1-30 mg/kg, 1-20 mg/kg or 1-10
  • the effective amount of one or more antiviral drugs is 100-2400mg, preferably 100mg-2300mg, 100mg-2200mg, 100mg-2100mg, 100mg-2000mg, 100mg-1900mg, 100mg-1800mg, 100mg-1700mg, 100mg-1600mg, 100mg-1800mg, 100mg-1800mg, 100mg-1800mg, 100mg-1800mg, 100mg-1800mg, more preferably 100mg, 200mg, 300mg, 400mg, 600mg, 500mg , 700mg, 800mg, 900mg, 1000mg.
  • one or more antiviral drugs is 100-2400mg, preferably 100mg-2300mg, 100mg-2200mg, 100mg-2100mg, 100mg-2000mg, 100mg-1900mg, 100mg-1800mg, 100mg-1700mg, 100mg-1600mg, 100mg
  • the effective amount of the antiviral drug is 0.1-100 mg/kg, preferably 1-90 mg/kg, 1-80 mg/kg, 1-70 mg/kg, 1-60 mg/kg, 1-50 mg/kg, 1-40 mg/kg, 1-30 mg/kg, 1-20 mg/kg or 1-10 mg/kg.
  • a single pharmaceutical dosage unit comprising 0.001 mg-1000 mg of the antibody or antigen-binding fragment thereof of the invention, preferably 0.001 mg-900 mg, 0.001 mg-800 mg, 0.001 mg-700 mg, 0.001 mg - 600mg, 0.001mg-500mg, 0.001mg-400mg, 0.001mg-300mg, 0.001mg-200mg, 0.001mg-100mg, more preferably 100mg, 200mg, 300mg, 400mg, 500mg, 600mg, 700mg, 800mg, 900mg or 1000mg
  • the antibody or antigen-binding fragment thereof of the present invention preferably 100mg, 200mg, 300mg, 400mg, 500mg, 600mg, 700mg, 800mg, 900mg or 1000mg
  • the antibody or antigen-binding fragment thereof of the present invention preferably 0.001 mg-1000 mg of the antibody or antigen-binding fragment thereof of
  • hybridoma cell line LT014 which was deposited in China, Wuhan, China on June 21, 2018, China Collection Center for Type Cultures (CCTCC), and the deposit number is CCTCC NO: C2018137.
  • Another aspect of the present invention also relates to the anti-CD73 antibody or its antigen-binding fragment, conjugate or fusion protein or multispecific antibody of the present invention, which is used as an adjuvant to enhance the immune response of an organism to an antigen.
  • the antigen is derived from a virus, bacteria, fungus, rickettsia, chlamydia, mycoplasma, parasite, prion, or tumor;
  • the virus includes RNA virus and DNA virus;
  • the RNA virus comprises a Coronaviridae virus
  • the coronavirus includes 2019 novel coronavirus (2019-nCoV or SARS-CoV-2, which causes novel coronavirus pneumonia COVID-19), HCoV-229E, HCoV-OC43, HCoV-NL63, HCoV-HKU1, SARS -CoV (which causes severe acute respiratory syndrome) and MERS-CoV (which causes Middle East respiratory syndrome).
  • 2019 novel coronavirus 2019-nCoV or SARS-CoV-2, which causes novel coronavirus pneumonia COVID-19
  • HCoV-229E HCoV-OC43
  • HCoV-NL63 HCoV-NL63
  • HCoV-HKU1 SARS -CoV
  • SARS -CoV which causes severe acute respiratory syndrome
  • MERS-CoV which causes Middle East respiratory syndrome
  • Another aspect of the present invention relates to a method of increasing the efficacy of a vaccine or enhancing the responsiveness of an organism to a vaccine, comprising administering to the subject an anti-CD73 antibody of the present invention at the same time, before or after administering the vaccine to the subject or antigen-binding fragments, conjugates, fusion proteins or multispecific antibodies thereof, preferably the antigens contained in the vaccine are derived from viruses, bacteria, fungi, rickettsia, chlamydia, mycoplasma, parasites, prions or tumors ;
  • the virus includes RNA virus and DNA virus;
  • the RNA virus comprises a coronavirus
  • the coronavirus includes 2019 novel coronavirus (2019-nCoV or SARS-CoV-2, which causes novel coronavirus pneumonia COVID-19), HCoV-229E, HCoV-OC43, HCoV-NL63, HCoV-HKU1, SARS -CoV (which causes severe acute respiratory syndrome) and MERS-CoV (which causes Middle East respiratory syndrome).
  • 2019 novel coronavirus 2019-nCoV or SARS-CoV-2, which causes novel coronavirus pneumonia COVID-19
  • HCoV-229E HCoV-OC43
  • HCoV-NL63 HCoV-NL63
  • HCoV-HKU1 SARS -CoV
  • SARS -CoV which causes severe acute respiratory syndrome
  • MERS-CoV which causes Middle East respiratory syndrome
  • the anti-CD73 antibody or antigen-binding fragment, conjugate, fusion protein or multispecific antibody thereof is administered, preferably intravenously, one or more times.
  • EC 50 refers to the concentration for 50% of maximal effect, which refers to the concentration that elicits 50% of the maximal effect.
  • antibody refers to an immunoglobulin molecule generally composed of two pairs of polypeptide chains, each pair having one "light” (L) chain and one "heavy” (H) chain.
  • Antibody light chains can be classified as kappa and lambda light chains.
  • Heavy chains can be classified as mu, delta, gamma, alpha, or epsilon, and define the antibody's isotype as IgM, IgD, IgG, IgA, and IgE, respectively.
  • the variable and constant regions are linked by a "J" region of about 12 or more amino acids, and the heavy chain also contains a "D" region of about 3 or more amino acids.
  • Each heavy chain consists of a heavy chain variable region ( VH ) and a heavy chain constant region ( CH ).
  • the heavy chain constant region consists of 3 domains ( CH1 , CH2 and CH3 ).
  • Each light chain consists of a light chain variable region ( VL ) and a light chain constant region ( CL ).
  • the light chain constant region consists of one domain, CL .
  • the constant regions of the antibodies mediate the binding of the immunoglobulin to host tissues or factors, including various cells of the immune system (eg, effector cells) and the first component (Clq) of the classical complement system.
  • the VH and VL regions can also be subdivided into regions of high variability called complementarity determining regions (CDRs) interspersed with more conserved regions called framework regions (FRs).
  • CDRs complementarity determining regions
  • Each VH and VL consists of 3 CDRs and 4 FRs arranged in the following order: FR1, CDR1, FR2, CDR2, FR3, CDR3, FR4 from amino terminus to carboxy terminus.
  • the assignment of amino acids to regions or domains follows the Kabat Sequences of Proteins of Immunological Interest (National Institutes of Health, Bethesda Md (1987 and 1991)), or Chothia & Lesk J. Mol. Biol. 1987; 196: 901-917; Chothia et al.
  • IMGT/3Dstructure-DB and IMGT/DomainGapAlign a database and a tool for immunoglobulins or antibodies
  • Definition of T cell receptors, MHC, IgSF and MhcSF Nucleic acids research 2009;38(suppl_1):D301-D307.
  • the term "antibody” is not limited by any particular method of producing an antibody. For example, it includes, in particular, recombinant antibodies, monoclonal antibodies and polyclonal antibodies.
  • Antibodies can be of different isotypes, eg, IgG (eg, IgGl, IgG2, IgG3, or IgG4 subtype), IgAl, IgA2, IgD, IgE, or IgM antibodies.
  • IgG eg, IgGl, IgG2, IgG3, or IgG4 subtype
  • IgAl IgA2, IgD, IgE, or IgM antibodies.
  • the terms “monoclonal antibody” and “monoclonal antibody” refer to an antibody or a fragment of an antibody from a population of highly homologous antibody molecules, that is, excluding natural mutations that may arise spontaneously, A population of identical antibody molecules.
  • Monoclonal antibodies are highly specific for a single epitope on an antigen.
  • Polyclonal antibodies are relative to monoclonal antibodies, which generally comprise at least two or more different antibodies that generally recognize different epitopes on an antigen.
  • Monoclonal antibodies can usually be obtained using the hybridoma technology first reported by Kohler et al. ( G, Milstein C. Continuous cultures of fused cells secreting antibody of predefined specificity [J]. nature, 1975; 256(5517): 495), but can also be obtained by recombinant DNA technology (eg, see US Patent 4,816,567).
  • humanized antibody refers to the replacement of all or part of the CDR regions of a human immunoglobulin (acceptor antibody) with the CDR regions of a non-human antibody (donor antibody)
  • the antibody or antibody fragment of which the donor antibody can be a non-human (eg, mouse, rat or rabbit) antibody with the desired specificity, affinity or reactivity.
  • some amino acid residues in the framework region (FR) of the acceptor antibody can also be replaced by amino acid residues of corresponding non-human antibodies, or by amino acid residues of other antibodies, to further improve or optimize the performance of the antibody.
  • isolated refers to artificially obtained from the natural state. If an "isolated” substance or component occurs in nature, it may be due to a change in its natural environment, or separation of the substance from its natural environment, or both. For example, a certain unisolated polynucleotide or polypeptide naturally exists in a living animal, and the same polynucleotide or polypeptide with high purity isolated from this natural state is called isolated of.
  • isolated or isolated
  • the term "vector” refers to a nucleic acid delivery vehicle into which a polynucleotide can be inserted.
  • the vector can express the protein encoded by the inserted polynucleotide, the vector is called an expression vector.
  • the vector can be introduced into a host cell by transformation, transduction or transfection, so that the genetic material elements carried by it can be expressed in the host cell.
  • Vectors are well known to those skilled in the art and include, but are not limited to: plasmids; phagemids; cosmids; artificial chromosomes, such as yeast artificial chromosomes (YACs), bacterial artificial chromosomes (BACs) or P1 derived artificial chromosomes (PACs) ; Phage such as ⁇ phage or M13 phage and animal viruses.
  • YACs yeast artificial chromosomes
  • BACs bacterial artificial chromosomes
  • PACs P1 derived artificial chromosomes
  • Animal viruses that can be used as vectors include, but are not limited to, retroviruses (including lentiviruses), adenoviruses, adeno-associated viruses, herpesviruses (eg, herpes simplex virus), poxviruses, baculoviruses, papillomaviruses, papillomaviruses Polyoma vacuolar virus (eg SV40).
  • retroviruses including lentiviruses
  • adenoviruses eg, adeno-associated viruses
  • herpesviruses eg, herpes simplex virus
  • poxviruses baculoviruses
  • papillomaviruses papillomaviruses
  • Polyoma vacuolar virus eg SV40
  • a vector may contain a variety of elements that control expression, including, but not limited to, promoter sequences, transcription initiation sequences, enhancer sequences, selection elements, and
  • the term "host cell” refers to a cell that can be used to introduce a vector, including, but not limited to, prokaryotic cells such as Escherichia coli or Bacillus subtilis, fungal cells such as yeast cells or Aspergillus, etc., Insect cells such as S2 Drosophila cells or Sf9, or animal cells such as fibroblasts, CHO cells, COS cells, NSO cells, HeLa cells, GS cells, BHK cells, HEK 293 cells or human cells.
  • prokaryotic cells such as Escherichia coli or Bacillus subtilis
  • fungal cells such as yeast cells or Aspergillus, etc.
  • Insect cells such as S2 Drosophila cells or Sf9
  • animal cells such as fibroblasts, CHO cells, COS cells, NSO cells, HeLa cells, GS cells, BHK cells, HEK 293 cells or human cells.
  • an antibody that specifically binds to an antigen refers to an antibody that is less than about 10-5 M, such as less than about 10-6 M, 10-7 M, Binds the antigen with an affinity (K D ) of 10-8 M, 10-9 M, or 10-10 M or less.
  • KD refers to the dissociation equilibrium constant for a particular antibody-antigen interaction, which is used to describe the binding affinity between an antibody and an antigen.
  • antibodies exhibit a dissociation equilibrium constant (K D ) of less than about 10-5 M, eg, less than about 10-6 M, 10-7 M, 10-8 M, 10-9 M, or 10-10 M or less Binds antigen (eg, PD-1 protein).
  • KD can be determined using methods known to those skilled in the art, eg, using a Fortebio Molecular Interactometer.
  • amino acids are generally represented by one-letter and three-letter abbreviations well known in the art.
  • alanine can be represented by A or Ala.
  • the term "pharmaceutically acceptable carrier and/or excipient” refers to a carrier and/or excipient that is pharmacologically and/or physiologically compatible with the subject and the active ingredient, It is well known in the art (see e.g. Remington's Pharmaceutical Sciences. Edited by Gennaro AR, 19th ed. Pennsylvania: Mack Publishing Company, 1995) and includes, but is not limited to: pH adjusters, surfactants, adjuvants, ions Strength enhancer.
  • pH adjusting agents include but are not limited to phosphate buffers; surfactants include but are not limited to cationic, anionic or nonionic surfactants such as Tween-80; ionic strength enhancers include but are not limited to sodium chloride.
  • the term "single drug dosage unit” refers to the antibody or antigen-binding fragment thereof, the antibody-drug conjugate of the present invention to be administered to a subject or patient at the moment of the dosing regimen Or a single-dose pharmaceutical dosage form of the bispecific antibody (or a pharmaceutical composition comprising the same), such as in one ampoule.
  • the term "effective amount” refers to an amount sufficient to obtain, or at least partially obtain, the desired effect.
  • an effective amount for preventing a disease refers to an amount sufficient to prevent, prevent, or delay the onset of a disease; a therapeutically effective amount refers to an amount sufficient to cure or at least partially prevent a disease that has been The amount of disease and its complications in patients with the disease.
  • the monoclonal antibody of the present invention can specifically bind to CD73 well, and can very effectively inhibit the enzymatic reaction of CD73 in a non-substrate competition manner, induce the endocytosis of CD73 on the cell surface, and then reduce the production of adenosine ; Can still stimulate B cell activation and proliferation in an adenosine-independent manner.
  • Figure 5 The detection results of the addition of anti-CD73 antibody to MDA-MB-231 cells to induce the endocytosis of CD73 on the cell membrane surface, in which Figure 5A shows the MFI value, and Figure 5B shows the internalization rate.
  • Figure 6 The detection results of the addition of anti-CD73 antibody to U87-MG cells to induce the endocytosis of CD73 on the cell membrane surface, in which Figure 6A shows the MFI value, and Figure 6B shows the internalization rate.
  • Figure 8 The results of FACS detection of the binding activity of anti-CD73 antibody 19F3H2L3 (hG1DM) to CD8+T cells and CD19+B cells.
  • Figure 9 The detection results of the enzymatic activity of the anti-CD73 antibody 19F3H2L3 (hG1DM) inhibiting the expression of CD73 in human PBMC membranes.
  • the BALB/c mice used were purchased from the Guangdong Provincial Medical Laboratory Animal Center.
  • the used positive control antibody MEDI9447 (Oleclumab) was produced from Zhongshan Kangfang Bio-Pharmaceutical Co., Ltd., and its sequence was the same as the amino acid sequence of Oleclumab disclosed by Medlmmune Limited in the WHO drug information database and related patents. Constructed synthetic (https://www.who.int/medicines/publications/dr ⁇ ginformation/innlists/en/), marked as MEDI9447 or MEDI9447 (Akeso) or MEDI-9447 (Akeso) in the examples;
  • the used control antibody CPI-006 the generic name of the drug is Mupadolimab, produced from Zhongshan Kangfang Bio-Pharmaceutical Co., Ltd., and its sequence source is the same as that of WHO, WHO Drug Information, Proposed INN: List 125.2021, 35(2):484-485. The sequence is identical.
  • the amino acid sequence of the heavy chain of CPI-006 (Mupadolimab) is shown in SEQ ID NO: 21, and the amino acid sequence of the light chain of CPI-006 is shown in SEQ ID NO: 22.
  • the isotype control antibody used is the sequence of human anti-Hen Egg Lysozyme IgG (anti-HEL antibody, or human IgG, hIgG for short, or isotype control) Variable region sequence from Fab F10.6.6 sequence in Affinity maturation increases the stability and plasticity of the Fv domain of anti-protein antibodies published by Acierno et al. (Acierno et al. J Mol Biol. 2007; 374(1): 130-146.); hIgG1DM used in the examples is an anti-HEL isotype control antibody with hG1DM constant region sequence, prepared in the laboratory of Zhongshan Kangfang Biomedical Co., Ltd.
  • the normal human peripheral blood used was from Zhongshan Blood Bank, and the human peripheral blood cells were all isolated and prepared in Zhongshan Kangfang Bio-Pharmaceutical Co., Ltd. with the informed consent of the provider;
  • the FITC-labeled anti-human CD3 antibody used was from Biolegend, article number: 344804;
  • the PE-labeled anti-human CD19 antibody used was from Biolegend, article number: 302254;
  • the APC-labeled anti-human CD69 antibody used was From Biolegend, product number: 310910;
  • the APC-labeled anti-human CD83 antibody used was from Biolegend, product number: 305312;
  • the acridine orange staining solution used was from Thermofisher, product number: 93001;
  • the propidium iodide staining solution used was from BD , Cat.
  • APC-labeled mouse IgG1 isotype control antibody used is from Biolegend, Cat. No. 400122; Mouse IgG1 isotype control antibody used is from Thermofisher, Cat. No. 10400C; Bovine serum albumin (BSA) used From Sigma, product number: V900933-1KG; used RPMI 1640 from Gibco, product number: 22400-089; used fetal bovine serum from Excell bio, product number: FSP500; used sodium pyruvate from Gibco, product number: 11360 -070; the non-essential amino acids used were from Gibco, catalog number: 11140-050; the L-glutamine used was from Gibco, catalog number: 25030-081; the MDA-MB-231 used was from ATCC, catalog number: HTB- 26; The U87-MG used is from ATCC, item number: HTB-14; the CTG chromogenic solution used is One Solution Assay kit from promega, Cat. No. G8461;
  • the antigen used to prepare the anti-CD73 antibody was human NT5E-His (NT5E is Genbank ID: NP_002517.1, position: 1-552).
  • the spleen cells of the immunized mice were fused with mouse myeloma cells to prepare hybridoma cells.
  • human NT5E (NT5E is GenbankID: NP_002517.1, position: 1-552)-Biotin as an antigen
  • the hybridoma cells were screened by indirect ELISA to obtain hybridoma cells that can secrete antibodies that specifically bind to CD73.
  • the hybridoma cells obtained by screening were subjected to a limiting dilution method to obtain stable hybridoma cell lines.
  • the above hybridoma cell lines were named as hybridoma cell line LT014, respectively, and the monoclonal antibody secreted by them was named as 19F3.
  • Hybridoma cell line LT014 also known as CD73-19F3
  • CTCC China Center for Type Culture Collection
  • the deposit number is CCTCC NO: C2018137
  • the deposit address is China. Wuhan. Wuhan University , Zip Code: 430072.
  • the LT014 cell lines prepared above were separately cultured with CD medium (Chemical Defined Medium) (CD medium containing 1% penicillin streptomycin, cultured in 5% CO 2 , 37° C. cell incubator). After 7 days, the cell culture supernatant was collected, subjected to high-speed centrifugation, vacuum filtration through a microporous membrane, and purified using a HiTrap protein A HP column to obtain antibody 19F3, respectively.
  • CD medium Cosmetic Defined Medium
  • CD medium containing 1% penicillin streptomycin cultured in 5% CO 2 , 37° C. cell incubator
  • mRNA was extracted from the LT014 cell line cultured in Example 1 according to the method of the Cultured Cell Bacterial Total RNA Extraction Kit (Tiangen, Cat. No. DP430).
  • the PCR amplification product was directly cloned by TA, and the specific operation was carried out by referring to the instructions of the pEASY-T1 Cloning Kit (Transgen CT101).
  • the nucleic acid sequence of the heavy chain variable region is shown in SEQ ID NO: 1, and the length is 363 bp.
  • the sequence of heavy chain CDR1 is shown in SEQ ID NO: 15
  • the sequence of heavy chain CDR2 is shown in SEQ ID NO: 16
  • the sequence of heavy chain CDR3 is shown in SEQ ID NO: 17.
  • the nucleic acid sequence of the light chain variable region is shown in SEQ ID NO: 3, and the length is 339 bp.
  • the sequence of light chain CDR1 is shown in SEQ ID NO: 18, the sequence of light chain CDR2 is shown in SEQ ID NO: 19, and the sequence of light chain CDR3 is shown in SEQ ID NO: 20.
  • the antibody model was simulated by computer, and the mutation was designed according to the model to obtain the variable region sequence of the antibody 19F3H1L1, 19F3H2L2, 19F3H2L3 (antibody constant region sequence, from the database of NCBI , the heavy chain constant region adopts the Ig gamma-1 chain C region, ACCESSION: P01857; the light chain constant region is the Ig kappa chain C region, ACCESSION: P01834).
  • variable region sequences are as follows:
  • the nucleic acid sequence of the heavy chain variable region is shown in SEQ ID NO: 5, and the length is 363 bp.
  • the encoded amino acid sequence is shown in SEQ ID NO: 6, and the length is 121aa, wherein the sequence of the heavy chain CDR1 is shown in SEQ ID NO: 15, the sequence of the heavy chain CDR2 is shown in SEQ ID NO: 16, and the heavy chain CDR3 The sequence is shown in SEQ ID NO: 17.
  • the nucleic acid sequence of the light chain variable region is shown in SEQ ID NO: 7, and the length is 339 bp.
  • the encoded amino acid sequence is shown in SEQ ID NO: 8, and the length is 113aa, wherein the sequence of light chain CDR1 is shown in SEQ ID NO: 18, the sequence of light chain CDR2 is shown in SEQ ID NO: 19, and the light chain CDR3 The sequence is shown in SEQ ID NO: 20.
  • the nucleic acid sequence of the heavy chain variable region is shown in SEQ ID NO: 9, and the length is 363 bp.
  • the encoded amino acid sequence is shown in SEQ ID NO: 10, and the length is 121aa, wherein the sequence of heavy chain CDR1 is shown in SEQ ID NO: 15, the sequence of heavy chain CDR2 is shown in SEQ ID NO: 16, and the heavy chain CDR3 The sequence is shown in SEQ ID NO: 17.
  • the nucleic acid sequence of the light chain variable region is shown in SEQ ID NO: 11, and the length is 339 bp.
  • the encoded amino acid sequence is shown in SEQ ID NO: 12, and the length is 113aa, wherein the sequence of light chain CDR1 is shown in SEQ ID NO: 18, the sequence of light chain CDR2 is shown in SEQ ID NO: 19, and the light chain CDR3 The sequence is shown in SEQ ID NO: 20.
  • the nucleic acid sequence of the heavy chain variable region is shown in SEQ ID NO: 9, and the length is 363 bp.
  • the encoded amino acid sequence is shown in SEQ ID NO: 10, and the length is 121aa, wherein the sequence of heavy chain CDR1 is shown in SEQ ID NO: 15, the sequence of heavy chain CDR2 is shown in SEQ ID NO: 16, and the heavy chain CDR3 The sequence is shown in SEQ ID NO: 17.
  • the nucleic acid sequence of the light chain variable region is shown in SEQ ID NO: 13, and the length is 339 bp.
  • the encoded amino acid sequence is shown in SEQ ID NO: 14, and the length is 113aa, wherein the sequence of light chain CDR1 is shown in SEQ ID NO: 18, the sequence of light chain CDR2 is shown in SEQ ID NO: 19, and the light chain CDR3 The sequence is shown in SEQ ID NO: 20.
  • the heavy chain constant region adopts the Ig gamma-1 chain C region, ACCESSION: P01857; the light chain constant region adopts the Ig kappa chain C region, ACCESSION: P01834.
  • 19F3H1L1 heavy chain cDNA and light chain cDNA, 19F3H2L2 heavy chain cDNA and light chain cDNA, and 19F3H2L3 heavy chain cDNA and light chain cDNA were cloned into the pUC57simple (provided by GenScript) vector, respectively, to obtain pUC57simple -19F3H1, pUC57simple-19F3L1; pUC57simple-19F3H2, pUC57simple-19F3L2 and pUC57simple-19F3L3.
  • the recombinant plasmids containing the corresponding light and heavy chains were designed to combine the genes (pcDNA3.1-19F3H1/pcDNA3.1-19F3L1, pcDNA3.1-19F3H2/pcDNA3.1-19F3L2, and pcDNA3.1-19F3H2/pcDNA3.1- 19F3L3) were co-transfected into 293F cells and the culture medium was collected for purification. After the sequencing was verified to be correct, an endotoxin-free expression plasmid was prepared and the plasmid was transiently transfected into HEK293 cells for antibody expression. After 7 days of culture, the cell culture medium was collected, and a Protein A column was used for affinity purification to obtain humanized antibodies.
  • the light chain constant region of the antibody of 19F3H2L3 is the Ig kappa chain C region, ACCESSION: P01834, see SEQ ID NO: 22.
  • the heavy chain constant region is based on the Ig gamma-1 chain C region, ACCESSION: P01857, and a leucine-to-alanine point mutation (L234A) was introduced at position 234, and leucine was introduced at position 235.
  • Amino acid to alanine point mutation (L235A) a humanized antibody named 19F3H2L3 (hG1DM) was obtained, the full-length amino acid sequence of the heavy chain of 19F3H2L3 (hG1DM) is shown in SEQ ID NO: 23, 19F3H2L3 (hG1DM) The full-length light chain amino acid sequence is shown in SEQ ID NO:24.
  • the heavy chain cDNA and light chain cDNA of 19F3H2L3 were cloned into pUC57simple (provided by GenScript) vector to obtain pUC57simple-19F3H2 (hG1DM) and pUC57simple-19F3L3, respectively.
  • 293F cells were co-transfected with the corresponding light and heavy chain recombinant plasmid design gene combination (pcDNA3.1-19F3H2(hG1DM)/pcDNA3.1-19F3L3) and the culture medium was collected for purification. After the sequencing was verified to be correct, an endotoxin-free expression plasmid was prepared and the plasmid was transiently transfected into HEK293 cells for antibody expression. After 7 days of culture, the cell culture medium was collected, and a Protein A column was used for affinity purification to obtain humanized antibodies.
  • CD69 is a C-type transmembrane glycoprotein, which is often expressed on the surface of activated T, B, NK and other lymphocytes, and is usually used as a marker for early activation of lymphocytes.
  • CD83 is another early activation marker, which is not only widely expressed in mature DCs, but also expressed in activated immune cells such as B lymphocytes. It can prevent the degradation of MHC class II and CD86 molecules on the cell surface and participate in immune regulation. After activation, B cells can become memory B cells or plasma cells to secrete antibodies and cytokines, and participate in the immune response to infection by viruses and other exogenous microorganisms.
  • CD69 and CD83 were used as molecular markers of B cell activation.
  • the MFI value and positive rate of CD69 and CD83 were positively correlated with B cell activation activity.
  • mouse IgG isotype control antibody (final concentration 5 ⁇ g/mL) to each well, incubate on ice for 20 min, centrifuge at 750*g for 5 min to remove the supernatant, and add 100 ⁇ L of the following secondary antibodies to each well of each group: FITC-labeled anti-human CD3 antibody (50-fold dilution), PE-labeled anti-human CD19 antibody (50-fold dilution), APC-labeled anti-human CD69 antibody (100-fold dilution), APC-labeled anti-human CD83 antibody (50-fold dilution), APC-labeled mouse IgG1 isotype Control antibody (100-fold dilution), incubate on ice for 40 minutes in the dark, add 100 ⁇ L of 1% PBSA (PBS containing 1% BSA) to each well, centrifuge at 750*g for 5 minutes to remove the supernatant, and resuspend at 200
  • Flowing software made flow histograms and scatter plots, and analyzed the MFI values of CD69 and CD83 expression in CD3-CD19+ cell subsets. According to the corresponding MFI values, Graphpad prism software was used to plot the mean ⁇ standard deviation SD and single factor analysis was performed. Analysis of variance, P ⁇ 0.05 has a significant difference, P ⁇ 0.01 has a very significant difference.
  • Example 5 Detection of anti-CD73 antibody on inhibition of endogenous expression of CD73 enzymatic activity in cells
  • the experimental steps are as follows: take log-phase MDA-MB-231 cells in good condition, resuspend and count the cells with serum-free RPMI-1640 medium; inoculate MDA-MB-231 cells into 96-well plates, 3*10 4 cells/100 ⁇ l/well; dilute the antibody with serum-free RPMI-1640 medium, the initial concentration is 200 ⁇ g/ml, and carry out a 2.5-fold gradient dilution; add the antibody to a 96-well plate, 50 ⁇ l per well, and incubate at 37°C for 1 hour.
  • the experimental steps are as follows: take log-phase U87-MG cells in good condition, resuspend and count the cells with serum-free RPMI-1640 medium; inoculate U87-MG cells into 96-well plates, 3*10 4 cells/ 100 ⁇ l/well; dilute the antibody with serum-free RPMI-1640 medium, the initial concentration is 200 ⁇ g/ml, and carry out a 2.5-fold gradient dilution; add the antibody to a 96-well plate, 50 ⁇ l per well, and incubate at 37°C for 1 hour; after 1 hour, Add 50 ⁇ l of 600 ⁇ M AMP diluted in RPMI-1640 to each well; after 3 hours, take 25 ⁇ l of cell culture supernatant, transfer it to a new 96-well plate, and add 25 ⁇ l of 100 ⁇ M ATP and 50 ⁇ l CTG to each well
  • One Solution Assay promega, Cat: G8461
  • Experimental steps culture cells in complete medium to logarithmic phase, 170 ⁇ g, 5min to collect cells, count and viability of cells, 30w/sample.
  • Add the corresponding 200 ⁇ L of complete medium to each tube, and carry out endocytosis for different time periods at 37°C.
  • 1% PBSA containing 0.05% sodium azide, SIGMA, product number: S2002-25G
  • 1000 ⁇ L of 1% PBSA was centrifuged at 1200 ⁇ g for 5 min.
  • 100 ⁇ L of corresponding fluorescent secondary antibody was added to each tube, mix well, and incubate on ice for 40 min in the dark.
  • 1000 ⁇ L of 1% PBSA containing 0.05% sodium azide
  • 1200 ⁇ g centrifuge for 5 min, and discard the supernatant.
  • 200 ⁇ L of 1% PBSA (containing 0.05% sodium azide)/tube resuspend the cells, transfer to the flow sample tube, and test on the machine.
  • Example 7 ELISA method to determine the binding activity of anti-CD73 antibody to antigen human NT5E-Biotin
  • the antibody diluted in PBST solution was added to the wells of the microtiter plate.
  • the antibody dilution gradient is shown in Table 1.
  • the ELISA plate with the antibody to be tested was incubated at 37°C for 30 minutes, and the plate was washed 3 times with PBST after the incubation. After washing the plate, add HRP-labeled goat anti-human IgG (H+L) (Jackson, Cat. No.: 109-035-088) diluted 1:5000 or HRP-labeled goat anti-mouse IgG (H+L) diluted 1:5000 (Jackson, Cat. No. 115-035-062) secondary antibody working solution, incubate at 37°C for 30 minutes.
  • Table 1 shows the OD values of each dose for detecting the binding of anti-CD73 antibody to the antigen human NT5E-Biotin. Taking the antibody concentration as the abscissa and the absorbance value as the ordinate, curve fitting was performed to calculate the binding EC 50 of the antibody. The results are shown in Table 1 below.
  • the experimental results showed that the antibodies 19F3H1L1, 19F3H2L2, 19F3H2L3 and the murine antibody 19F3 could effectively bind to human NT5E-Biotin, and the binding efficiency was dose-dependent.
  • the EC50 of 19F3H1L1 binding to human NT5E-Biotin was 0.049nM
  • the EC50 of 19F3H2L2 binding to human NT5E-Biotin was 0.064nM
  • the EC50 of 19F3H2L3 binding to human NT5E-Biotin was 0.061nM
  • the EC50 of the same target-positive drug MEDI9447 binding to human NT5E-Biotin was 0.048nM
  • the EC50 of murine antibody 19F3 binding to human NT5E -Biotin was 0.018nM
  • hIgG1DM produced by Zhongshan Kangfang Biopharmaceutical Co., Ltd.
  • S protein nCoV_SRBD-mFc, see YP_009724390.1 for the sequence), produced by Zhongshan Kangfang Biopharmaceutical Co., Ltd.
  • CFA Complete Fisher's Adjuvant
  • SIGMA Item No.: F5881 -10ml
  • IFA Incomplete Freund's Adjuvant
  • IP intraperitoneal injection
  • BIW*6 twice a week for a total of 6 doses
  • Example 9 FACS detection of the binding activity of anti-CD73 antibody 19F3H2L3 (hG1DM) to CD8+ T cells and CD19+ B cells
  • PBMC peripheral blood mononuclear cells
  • the experimental steps were as follows: PBMC were recovered, centrifuged at 1200 rpm for 5 min, the supernatant was discarded, resuspended in complete medium, counted, and cultured at 37°C overnight. Centrifuge at 1200 rpm for 5 min, collect cells, add 100 ⁇ L/well of diluted antibody solution, mix well, and incubate at 4°C for 1 hour. Centrifuge at 750 x g for 5 min, discard the supernatant, and wash twice with 200 ⁇ L of 1X PBS (containing 1% BSA and 0.05% NaN3). Add anti-human CD3-FITC (2 ⁇ L/100 ⁇ L), anti-human CD19-PE (2 ⁇ L/100 ⁇ L) (Biolegend, Cat.
  • Both 19F3H2L3 (hG1DM) and the same target positive control drug CPI-006 can dose-dependently bind to CD73 expressed by human CD8 + T and CD19 + B cells, thereby increasing the mean fluorescence intensity MFI (Mean Fluorescence Intensity) in a dose-dependent manner .
  • MFI Mean Fluorescence Intensity
  • Example 10 Anti-CD73 antibody 19F3H2L3 (hG1DM) inhibits the enzymatic activity of human PBMC membrane-expressed CD73
  • the experimental procedure was as follows: fresh human PBMCs were isolated by gradient density centrifugation and resuspended in assay medium (RPMI-1640 without serum). The cell number and viability were counted, and 10*10 4 cells/well were inoculated into a 96-well plate, 60 ⁇ L/well. Dilute the antibody with assay medium to the following concentrations: 30, 10, 3.3, 1.1, 0.11, 0.011, 0.0011, 0.00011 ⁇ g/mL, add the antibody to a 96-well plate, 60 ⁇ L/well, mix gently with cells, and place on Incubate at 37°C for 30min.
  • the AMP solution (TCI, Cat.
  • A0158 with a concentration of 60 ⁇ M was prepared with the analysis medium and used for standby; the ATP solution with a concentration of 30 ⁇ M was prepared with TM buffer (akesobio, 20191009) for standby.
  • TM buffer akesobio, 20191009
  • Anti-CD73 antibody inhibits the enzymatic activity of human PBMC membrane-expressed CD73
  • Example 11 FACS detection of anti-CD73 antibody 19F3H2L3 (hG1DM) effectively induces B cell activation
  • CD69 is a C-type transmembrane glycoprotein, which is often expressed on the surface of activated T, B, NK and other lymphocytes, and is usually used as a marker for early activation of lymphocytes.
  • CD83 is another early activation marker, which is not only widely expressed in mature DCs, but also expressed in activated immune cells such as B lymphocytes. It can prevent the degradation of MHC class II and CD86 molecules on the cell surface and participate in immune regulation.
  • B cells can become memory B cells or plasma cells to secrete antibodies and cytokines, and participate in the immune response to infection by viruses and other exogenous microorganisms.
  • Activated B cells produce IgM-based antibodies.
  • HLA-DR is an MHC-II molecule and is expressed on B cells.
  • HLA-DR expression is a sign of B lymphocyte activation. Therefore, in this experiment, CD69, CD83, HLA-DR, and IgM were used as molecular markers of B cell activation. The MFI value and positive rate of CD69, CD83, HLA-DR, and IgM were positively correlated with B cell activation activity.
  • B cells were recovered, resuspended in complete medium, counted, and seeded in 96-well plates at 100,000 cells/100 ⁇ L/well, with 2 duplicate wells in each group; antibody or APCP ( ⁇ , ⁇ -methyleneadenosine 5) was added.
  • APCP ⁇ , ⁇ -methyleneadenosine 5
  • FACS operation steps Gently mix the B cells in each well of the well plate, and evenly transfer them to 5 wells of a 96-well plate, 750 ⁇ g, 5min to remove the supernatant, resuspend in PBSA (PBS containing 1% BSA), and add mouse IgG (Mouse IgG Isotype Control) 100 ⁇ l/well, the final concentration is 5 ⁇ g/ml, incubate on ice for 20min, 750xg, 5min discard the supernatant, add Mix1/2/3/4/5/6/7 respectively.
  • PBSA PBS containing 1% BSA
  • mouse IgG mouse IgG Isotype Control
  • PBSA 100 ⁇ l PBSA contains 2 ⁇ l FITC anti-human CD3 (purchased from Biolegend, product number: 344804) + 2 ⁇ l PE anti-human CD19 (purchased from Biolegend, product number: 302254);
  • PBSA 100 ⁇ l PBSA contains 2 ⁇ l FITC anti-human CD3+2 ⁇ l PE anti-human CD19+1 ⁇ l APC anti-human CD69 (purchased from Biolegend, catalog number: 310910);
  • PBSA 100 ⁇ l PBSA contains 2 ⁇ l FITC anti-human CD3+2 ⁇ l PE anti-human CD19+2 ⁇ l APC anti-human CD83 (purchased from Biolegend, catalog number: 305312);
  • PBSA contains 2 ⁇ l FITC anti-human CD3+2 ⁇ l PE anti-human CD19+2 ⁇ l APC anti-human HLA-DR (purchased from Biolegend, product number: 361610);
  • PBSA 100 ⁇ l PBSA contains 2 ⁇ l FITC anti-human CD3+2 ⁇ l PE anti-human CD19+2 ⁇ l APC anti-human IgD (purchased from Biolegend, catalog number: 348222)+2 ⁇ l PerCP/Cyanine5.5 anti-human CD27 antibody (Biolegend, Item No.: 356408);
  • PBSA contains 2 ⁇ l FITC anti-human CD3+2 ⁇ l PE anti-human CD19+2 ⁇ l APC anti-human IgM (purchased from Biolegend, product number: 314510).
  • the CD73 enzyme activity inhibitor APCP (Sigma, catalog number: M3763-10MG) had no effect on the expression of CD69, CD83, HLA-DR, and IgM on the surface of B cells, indicating that 19F3H2L3 (hG1DM) can inhibit the enzyme activity through a different signal pathway than CD73. Induce the activation of B cells.
  • PBMCs were recovered, centrifuged at 250 ⁇ g for 5 min, resuspended in complete medium, and counted. Complete medium was discarded by centrifugation, washed once with RPMI-1640, and resuspended.
  • 0.25 ⁇ M CFSE Biolegend, Cat. No.: 423801
  • solution to 1 ⁇ 10 6 cells/mL, incubate at 37°C in the dark for 2 min; add 2 to 3 times serum-containing medium to stop, centrifuge at 250 ⁇ g (1200 rpm) for 5 min and discard.
  • MS mouse IgG Thermofisher, Cat. No.: 10400C
  • Nucleic acid sequence of 19F3H1L1 heavy chain variable region (SEQ ID NO: 5)
  • Nucleic acid sequences of 19F3H2L2 and 19F3H2L3 heavy chain variable regions (SEQ ID NO: 9)
  • Amino acid sequences of 19F3H2L2 and 19F3H2L3 heavy chain variable regions (SEQ ID NO: 10)
  • HCDR1 GYSFTGYT (SEQ ID NO: 15)
  • HCDR2 INPYNAGT (SEQ ID NO: 16)
  • HCDR3 ARSEYRYGGDYFDY (SEQ ID NO: 17)
  • LCDR1 QSLLNSSNQKNY (SEQ ID NO: 18)
  • LCDR2 FAS (SEQ ID NO: 19)
  • LCDR3 QQHYDTPYT (SEQ ID NO: 20)

Abstract

提供了抗CD73抗体及其在治疗冠状病毒感染引起的疾病中的应用。具体地，所述抗体的重链可变区包含氨基酸序列如SEQ ID NOs：15-17所示的HCDR1-HCDR3；并且所述抗体的轻链可变区包含氨基酸序列如SEQ ID NOs：18-20所示的LCDR1-LCDR3。

Description

抗CD73的抗体及其用途 技术领域
本发明涉及免疫学领域。具体地，涉及抗CD73抗体及其用途。
背景技术
胞外-5′-核苷酸酶(Ecto-5′-nucleotidase)，即CD73蛋白，是NT5E基因编码的一种蛋白分子量为70KD的多功能糖蛋白，其通过糖基磷脂酰肌醇(glyocsyl phosphatidy linositol，GPI)锚定于细胞膜上(Zimmermann H.Biochem J.1992；285：345-365)。
CD73广泛分布在人体组织细胞表面，在免疫细胞表面亦广泛表达，如树突细胞、调节型T细胞(Treg)、自然杀伤细胞(NK细胞)、髓系起源的抑制细胞(MDSC)等。
CD73既有水解酶活性，又有非水解酶作用。CD73的酶与非酶功能的一个免疫抑制机制是由CD73-腺苷(Adenosine)代谢信号通路介导的，CD73上游的CD39可以催化ATP产生腺苷单磷酸(AMP)，所产生的AMP被CD73转化为腺苷，而腺苷会结合下游的腺苷受体(A2AR)，A2AR通过激活蛋白激酶A(PKA)和Csk激酶，抑制LCK、MAPK、PKC等一系列与免疫激活相关的信号通路，抑制T细胞的免疫杀伤作用，从而发挥免疫抑制作用(Antonioli L，et al.Nat Rev Cancer.2013；13：842-857.)。
冠状病毒科病毒包括2019新型冠状病毒(2019-nCoV或SARS-CoV-2，引发新型冠状病毒肺炎COVID-19)，HCoV-229E、HCoV-OC43、HCoV-NL63、HCoV-HKU1、SARS-CoV(引发重症急性呼吸综合征)和MERS-CoV(引发中东呼吸综合征)。上述病毒的感染可以导致严重的临床症状甚至威胁生命。
SARS-CoV通过不同的机制来对抗免疫应答。其中一种机制是通过抑制1型干扰素(IFN-1)的表达和信号传导(Kindler，E.，Thiel et al.SARS-CoV and IFN：Too Little，Too Late.Cell Host Microbe 2016，19(2)，139-141.)。诱导型I型干扰素通过诱导细胞对病毒感染的抵抗和促进病毒感染细胞的 凋亡，在抗病毒免疫反应中发挥关键作用。SARS-CoV阻碍了IFN-I的快速增加，这促进了冠状病毒的复制。ATP可促进IFN的产生，已经证明，改善细胞外ATP可以通过信号通路P38/JNK/ATF-2促进IFN的分泌，从而逆转这个循环。因此，缺乏ATP的细胞更容易受到病毒感染，如SARS-CoV和COVID-19(Taghizadeh-Hesary F.，Akbari H.The Powerfμl Immune System Against Powerfμl COVID-19：A Hypothesis.Medical Hypotheses，2020，109762.)。体外实验表明，SARS-CoV-2表达多种抑制干扰素的蛋白质(Konno，Yoriyuki，et al.SARS-CoV-2 ORF3b is a potent interferon antagonist whose activity is further increased by a naturally occurring elongation variant.bioRxiv(2020).Yuen，Chun-Kit，et al.SARS-CoV-2 nsp13，nsp14，nsp15 and orf6 function as potent interferon antagonists.Emerging Microbes and Infections(2020)：1-29.)，因此证明这是抑制有效早期免疫反应的关键机制。
[根据细则26改正30.08.2021]　
除了在急性期的作用外，干扰素在免疫抑制调节性T细胞(Treg)的发育中也起着至关重要的作用。严重COVID-19患者的肺损伤与细胞因子释放综合征(CRS)相关，表明可能未能及时激活免疫抑制机制(Acharya，D.，Liu，G.&Gack，M.U.Dysregμlation of type I interferon responses in COVID-19.Nat Rev Immunol 20，397-398(2020).)。这得到了COVID-19患者调节性Treg计数的支持，显示其与疾病严重程度呈负相关。
抑制ATP降解途径可以做为治疗COVID-19的机制，ATP刺激干扰素的分泌，这可能对抗SARS-CoV-2强大的干扰素抑制机制。如果成功，这将有助于在感染的早期阶段消灭病毒。
新冠肺炎患者临床表现之一为缺氧、低氧血症，低氧诱导因子-1(HIF-1)等分子的上调，导致CD73广泛表达(Synnestvedt K，et al.J Clin Invest.2002；110：993-1002.)，此外，A2B受体在低氧状态下更容易激活，A2BR的激活直接促进了相关细胞产生大量IL-6，不但可以诱导肺纤维细胞的分化(Hongyan Zhong，Luiz Belardinelli et al.Synergy between A2B Adenosine Receptors and Hypoxia in Activating HμMan Lung Fibroblasts.Am  J Respir Cell Mol Biol，2005，32：2-8.)，而且IL-6是引发新冠肺炎患者细胞因子风暴中的关键炎症因子之一。因此，降低腺苷水平可能对患有CRS和呼吸窘迫的患者特别有益。多项研究报道在新型冠状肺炎重症患者中IL-6、GM-CSF在重症及危重症患者中显著升高(Characteristics of lymphocyte subsets and cytokines in peripheral blood of 123 hospitalized patients with 2019 novel coronavirus pneμMonia(NCP).Wan SX，Yi QJ，Fan SB，Lv JL，Zhang XX，Guo L，Lang CH，Xiao Q，Xiao KH，et al.medRxiv 2020.02.10.20021832；陈蕾，刘辉国，刘威等.2019新型冠状病毒肺炎29例临床特征分析.中华结核和呼吸杂志，2020，43：E005)。在严重急性呼吸系统综合症冠状病毒(SARS-CoV)感染中，研究同样证实了证实SARS-CoV 3a蛋白可直接激活巨噬细胞中的NLRP3炎性小体，介导下游IL-6升高的机制(Chen IY，Moriyama M，Chang MF，Ichinohe T.Severe Acute Respiratory Syndrome Coronavirus Viroporin 3a Activates the NLRP3Inflammasome.Front Microbiol.eCollection 2019)。
增强免疫应答可能导致更快的病毒清除，更短的恢复时间，更少的并发症，更长的免疫力和防止再次感染。增强免疫应答的能力为治疗COVID-19和其他流行病提供了一个潜在的机会。
CD73在人的B细胞、T细胞、骨髓细胞、骨髓基质细胞及胸腺上皮细胞均表达。有研究显示(Giovanni Forte，Rosalinda Sorrentino et al.Inhibition of CD73 Improves B Cell-Mediated Anti-TμMor Immunity in a Mouse Model of Melanoma.The Journal of Immunology，2012，189：2226-2233.)，拮抗CD73可以通过IL-17A影响B细胞产生IgG的活性，而IgG是抗细菌、抗毒素和抗病毒抗体的主要组成部分。在同属冠状病毒科病毒感染所致的新型冠状病毒肺炎(COVID-19)死亡患者尸检中发现，患者血液中的CD4+和CD8+T细胞数量显著减少，但是产生IL-17A的Th17细胞比例显著增加(Xu Z，Shi L，Wang YJ，Zhang JY，Huang L，Zhang C et al.Pathological findings of COVID-19 associated with acute respiratory distress syndrome.The Lancet Respiratory Medicine.2020)。
综上所述，阻断CD73可能是通过调节CD73腺苷途径和影响免疫应答可以用来治疗COVID-19在内的冠状病毒科病毒引起的疾病。
发明内容
本发明人利用哺乳动物细胞表达系统表达出重组的人CD73作为抗原免疫小鼠，经小鼠脾脏细胞与骨髓瘤细胞融合获得杂交瘤细胞。发明人通过对大量样本的筛选，得到了杂交瘤细胞株LT014(保藏编号为CCTCC NO：C2018137)。
本发明人惊奇地发现，杂交瘤细胞株LT014分别能够分泌产生与人CD73特异性结合的特异性单克隆抗体(命名为19F3)，进一步地，本发明人制得了抗人CD73的人源化抗体(命名为19F3H2L3)。
本发明人还惊奇地发现，本发明的抗体19F3H2L3能够十分有效地以非底物竞争的方式抑制CD73的酶活反应，降低腺苷的产生，促进细胞膜表面CD73的内吞，刺激B细胞的活化与增殖。本发明的抗体具有用于治疗冠状病毒感染引起相关疾病的效果。
本发明的一个方面涉及抗CD73(例如人CD73)抗体或其抗原结合片段，用于治疗和/或预防冠状病毒引起的感染，其中，所述抗CD73抗体包含：
或者所述抗CD73抗体包含SEQ ID NO：2、SEQ ID NO：6或SEQ ID NO：10所示重链可变区中包含的HCDR1，HCDR2和HCDR3，和SEQ ID NO：4、SEQ ID NO：8、SEQ ID NO：12或SEQ ID NO：14所示的轻链可变区中包含的LCDR1，LCDR2和LCDR3，
优选地，根据IMGT编号系统，所述抗CD73抗体包含：HCDR1，其包含SEQ ID NO：15所示的氨基酸序列，与所述序列具有至少80％，81％，82％，83％，84％，85％，86％、87％、88％、89％、90％，优选至少91％，92％，93％，94％，95％，96％，97％，98％或99％序列同一性的序列，或与所述序列相比具有一个或多个(优选1个、2个或3个)保守氨基酸突变(优选置换，插入或缺失)的氨基酸序列，或由其组成，
HCDR2，其包含SEQ ID NO：16所示的氨基酸序列，与所述序列具有至少80％，81％，82％，83％，84％，85％，86％、87％、88％、89％、90％，优选至少91％，92％，93％，94％，95％，96％，97％，98％或99％ 序列同一性的序列，或与所述序列相比具有一个或多个(优选1个、2个或3个)保守氨基酸突变(优选置换，插入或缺失)的氨基酸序列，或由其组成，
HCDR3，其包含SEQ ID NO：17所示的氨基酸序列，与所述序列具有至少80％，81％，82％，83％，84％，85％，86％、87％、88％、89％、90％，优选至少91％，92％，93％，94％，95％，96％，97％，98％或99％序列同一性的序列，或与所述序列相比具有一个或多个(优选1个、2个或3个)保守氨基酸突变(优选置换，插入或缺失)的氨基酸序列，或由其组成，
LCDR1，其包含SEQ ID NO：18所示的氨基酸序列，与所述序列具有至少80％，81％，82％，83％，84％，85％，86％、87％、88％、89％、90％，优选至少91％，92％，93％，94％，95％，96％，97％，98％或99％序列同一性的序列，或与所述序列相比具有一个或多个(优选1个、2个或3个)保守氨基酸突变(优选置换，插入或缺失)的氨基酸序列，或由其组成，
LCDR2，其包含SEQ ID NO：19所示的氨基酸序列，与所述序列具有至少80％，81％，82％，83％，84％，85％，86％、87％、88％、89％、90％，优选至少91％，92％，93％，94％，95％，96％，97％，98％或99％序列同一性的序列，或与所述序列相比具有一个或多个(优选1个、2个或3个)保守氨基酸突变(优选置换，插入或缺失)的氨基酸序列，或由其组成，和
LCDR3，其包含SEQ ID NO：20所示的氨基酸序列，与所述序列具有至少80％，81％，82％，83％，84％，85％，86％、87％、88％、89％、90％，优选至少91％，92％，93％，94％，95％，96％，97％，98％或99％序列同一性的序列，或与所述序列相比具有一个或多个(优选1个、2个或3个)保守氨基酸突变(优选置换，插入或缺失)的氨基酸序列，或由其组成。
在本发明的一些实施方案中，
所述抗体的重链可变区包含下述序列，或由下述序列组成：
SEQ ID NO：2、SEQ ID NO：6或SEQ ID NO：10，与SEQ ID NO：2、SEQ ID NO：6或SEQ ID NO：10具有至少80％、81％、82％、83％、84％、85％、86％、87％、88％、89％、90％、91％、92％、93％、94％、95％、96％、97％、98％或99％序列同一性的序列，或与SEQ ID NO：2、SEQ ID NO：6或SEQ ID NO：10所示的氨基酸序列相比具有一个或多个(优选1、2、3、4、5、6、7、8、9或10个)保守氨基酸突变(优选置换，插入或缺失)的氨基酸序列；并且
所述抗体的轻链可变区包含下述序列，或由下述序列组成：
SEQ ID NO：4、SEQ ID NO：8、SEQ ID NO：12或SEQ ID NO：14，与SEQ ID NO：4、SEQ ID NO：8、SEQ ID NO：12或SEQ ID NO：14具有至少80％、81％、82％、83％、84％、85％、86％、87％、88％、89％、90％、91％、92％、93％、94％、95％、96％、97％、98％或99％序列同一性的序列，或与SEQ ID NO：4、SEQ ID NO：8、SEQ ID NO：12或SEQ ID NO：14所示的氨基酸序列相比具有一个或多个(优选1、2、3、4、5、6、7、8、9或10个)保守氨基酸突变(优选置换，插入或缺失)的氨基酸序列。
在本发明的一些实施方案中，所述抗体的重链可变区的氨基酸序列如SEQ ID NO：2所示，并且所述抗体的轻链可变区的氨基酸序列如SEQ ID NO：4所示；
所述抗体的重链可变区的氨基酸序列如SEQ ID NO：6所示，并且所述抗体的轻链可变区的氨基酸序列如SEQ ID NO：8所示；
所述抗体的重链可变区的氨基酸序列如SEQ ID NO：10所示，并且所述抗体的轻链可变区的氨基酸序列如SEQ ID NO：12所示；或
所述抗体的重链可变区的氨基酸序列如SEQ ID NO：10所示，并且所述抗体的轻链可变区的氨基酸序列如SEQ ID NO：14所示。
在本发明的一些实施方案中，所述抗体的重链恒定区为Ig gamma-1链C区，ACCESSION：P01857；轻链恒定区为Ig kappa链C区，ACCESSION：P01834。
轻链和重链的可变区决定抗原的结合；每条链的可变区均含有三个高变区，称互补决定区(CDR)(重链(H)的CDR包含HCDR1、HCDR2、 HCDR3，轻链(L)的CDR包含LCDR1、LCDR2、LCDR3；其由Kabat等人命名，见Bethesda M.d.，Sequences of Proteins of Immunological Interest，Fifth Edition，NIH Publication 1991；1-3：91-3242。
优选地，CDR也可以由IMGT编号系统定义，请参见Ehrenmann，Francois，Quentin Kaas，and Marie-Paule Lefranc.IMGT/3Dstructure-DB and IMGT/DomainGapAlign：a database and a tool for immunoglobulins or antibodies，T cell receptors，MHC，IgSF and MhcSF.Nucleic acids research 2009；38(suppl_1)：D301-D307。
通过本领域技术人员所熟知的技术手段，例如通过VBASE2数据库根据IMGT定义分析单克隆抗体序列的CDR区的氨基酸序列。
在已知抗体重链和轻链可变区序列的情况下，目前有几种确定抗体CDR区的方法，包括Kabat，IMGT，Chothia和AbM编号系统。
然而，每种关于抗体或其变体的CDR的定义的应用都将在本文定义和使用的术语的范围内。如果给定该抗体的可变区氨基酸序列，则本领域技术人员通常可确定哪些残基包含特定CDR，而不依赖于该序列自身之外的任何实验数据。
本发明涉及的抗体19F3、19F3H1L1、19F3H2L2、19F3H2L3具有相同的CDR：
其重链可变区的3个CDR区的氨基酸序列如下：
HCDR1：GYSFTGYT(SEQ ID NO：15)，
HCDR2：INPYNAGT(SEQ ID NO：16)，
HCDR3：ARSEYRYGGDYFDY(SEQ ID NO：17)；
其轻链可变区的3个CDR区的氨基酸序列如下：
LCDR1：QSLLNSSNQKNY(SEQ ID NO：18)，
LCDR2：FAS(SEQ ID NO：19)，
LCDR3：QQHYDTPYT(SEQ ID NO：20)。
在本发明的一些实施方案中，所述抗体为单克隆抗体。
在本发明的一些实施方案中，所述抗体为人源化抗体、嵌合抗体、多特异性抗体(例如双特异性抗体)，优选地，所述抗CD73抗体的重链氨基酸序列如SEQ ID NO：23所示，轻链氨基酸序列如SEQ ID NO：24 所示。
在本发明的一些实施方式中，所述抗原结合片段选自Fab、Fab′、F(ab′) 2、Fd、Fv、dAb、Fab/c、互补决定区片段、单链抗体(例如，scFv)、人源化抗体、嵌合抗体或双特异性抗体。
本发明的再一方面涉及一种偶联物，用于治疗和/或预防冠状病毒引起的感染，其包括抗体以及偶联部分，其中，所述抗体为本发明任一项所述的抗CD73抗体或其抗原结合片段，所述偶联部分为纯化标签(如His标签)，可检测的标记或小分子药物；优选地，所述偶联部分为放射性同位素、荧光物质、化学发光物质、有色物质、聚乙二醇或酶；优选地，所述小分子药物为小分子细胞毒药物；更优选地，所述小分子药物为肿瘤化疗药物，更优选地，所述抗体或其抗原结合片段通过连接子与小分子药物连接；例如，所述连接子为腙键、二硫键或肽键；更优选地，所述抗体或其抗原结合片段与小分子药物以一定的摩尔比连接；例如，所述摩尔比为1∶(2-4)。
本发明的再一个方面，涉及融合蛋白或多特异性抗体(优选双特异性抗体)，用于治疗和/或预防冠状病毒引起的感染，其包含本发明任一项所述的抗CD73抗体或其抗原结合片段。
在本发明的再一个方面，涉及试剂盒，用于治疗和/或预防冠状病毒引起的感染，其包含有效量(例如0.001mg-1000mg)的本发明所述的抗CD73抗体或其抗原结合片段、本发明的偶联物、融合蛋白或多特异性抗体，和任选地，还包含有效量的一种或多种抗病毒药物(例如100-2400mg)。
在本发明的再一个方面，涉及试剂盒，用于治疗和/或预防冠状病毒引起的感染，所述试剂盒包括本发明所述抗CD73抗体或其抗原结合片段、偶联物、融合蛋白或多特异性抗体，和用作疫苗的抗原，所述用作疫苗的抗原选自源自病毒、细菌、真菌、立克次体、衣原体、支原体、寄生虫、朊病毒或肿瘤。
本发明的再一方面涉及一种药物组合物，用于治疗和/或预防冠状病毒引起的感染，其包含本发明任一项所述的抗CD73抗体或其抗原结合片段、本发明的偶联物、融合蛋白或多特异性抗体；可选地，所述药 物组合物还包括药学上可接受的载体和/或赋形剂。优选地，所述药物组合物为适于通过皮下注射、皮内注射、静脉内注射、肌内注射或病灶内注射施用的形式。
本发明的再一方面涉及本发明所述的用于治疗和/或预防冠状病毒引起的感染，抗体或其抗原结合片段、所述的偶联物或所述的融合蛋白或多特异性抗体，在制备治疗和/或预防冠状病毒感染的药物或试剂盒中的用途，优选地，所述冠状病毒选自新型冠状病毒SARS-CoV-2，HCoV-229E、HCoV-OC43、HCoV-NL63、HCoV-HKU1、SARS-CoV和/或MERS-CoV。
本发明的再一方面涉及治疗和/或预防冠状病毒感染的方法，包括向受试者或患者施用有效量的所述的抗CD73抗体或其抗原结合片段、所述的偶联物或所述的融合蛋白或多特异性抗体，优选地，所述冠状病毒科病毒选自新型冠状病毒SARS-CoV-2，HCoV-229E、HCoV-OC43、HCoV-NL63、HCoV-HKU1、SARS-CoV和/或MERS-CoV。在一些实施方案中，所述方法包括向受试者或患者同时或顺序施用抗病毒药物(如法匹拉韦)，优选地，所述抗病毒药物是RNA病毒抑制剂。
在一些实施方案中，本发明的抗CD73抗体或其抗原结合片段、所述的抗体药物偶联物或者所述的双特异性抗体的有效量为0.001mg-1000mg，更优选0.001mg-900mg、0.001mg-800mg、0.001mg-700mg、0.001mg-600mg、0.001mg-500mg、0.001mg-400mg、0.001mg-300mg、0.001mg-200mg、0.001mg-100mg，最优选为100mg、200mg、300mg、400mg、500mg、600mg、700mg、800mg、900mg或1000mg，或者，基于受试者或患者的体重，所述有效量为0.1-100mg/kg，优选1-90mg/kg、1-80mg/kg、1-70mg/kg、1-60mg/kg、1-50mg/kg、1-40mg/kg、1-30mg/kg、1-20mg/kg或1-10mg/kg。在本发明的上述任一实施方案，一种或多种抗病毒药物(例如法匹拉韦)的有效量为100-2400mg，优选100mg-2300mg、100mg-2200mg、100mg-2100mg、100mg-2000mg、100mg-1900mg、100mg-1800mg、100mg-1700mg、100mg-1600mg、100mg-1800mg、100mg-1800mg、100mg-1800mg、100mg-1800mg、100mg-1800mg，更优选为100mg，200mg，300mg，400mg，500mg，600mg，700mg，800mg，900mg，1000mg。或 者，在本发明的上述任一实施方案中，基于受试者或患者的体重，所述抗病毒药物的有效量为0.1-100mg/kg，优选1-90mg/kg、1-80mg/kg、1-70mg/kg、1-60mg/kg、1-50mg/kg、1-40mg/kg、1-30mg/kg、1-20mg/kg或1-10mg/kg。在本发明的另一个方面，涉及单次药物剂量单元，其包含0.001mg-1000mg的本发明的抗体或其抗原结合片段，优选0.001mg-900mg、0.001mg-800mg、0.001mg-700mg、0.001mg-600mg、0.001mg-500mg、0.001mg-400mg、0.001mg-300mg、0.001mg-200mg、0.001mg-100mg，更优选为100mg、200mg、300mg、400mg、500mg、600mg、700mg、800mg、900mg或1000mg的本发明的抗体或其抗原结合片段。
本发明的再一方面涉及杂交瘤细胞株LT014，其于2018年6月21日保藏在中国，武汉的中国典型培养物保藏中心(CCTCC)，保藏编号为CCTCC NO：C2018137。
本发明的另一个方面，还涉及本发明所述的抗CD73抗体或其抗原结合片段、偶联物或融合蛋白或多特异性抗体，其作为助剂用于增强生物体对抗原的免疫反应。在一些实施方案中，所述抗原源自病毒、细菌、真菌、立克次体、衣原体、支原体、寄生虫、朊病毒或肿瘤；；
优选地，所述病毒包括RNA病毒及DNA病毒；
优选地，所述RNA病毒包括冠状病毒科病毒；
优选地，所述冠状病毒包括2019新型冠状病毒(2019-nCoV或SARS-CoV-2，引发新型冠状病毒肺炎COVID-19)，HCoV-229E、HCoV-OC43、HCoV-NL63、HCoV-HKU1、SARS-CoV(引发重症急性呼吸综合征)和MERS-CoV(引发中东呼吸综合征)。
本发明的另一个方面，涉及提高疫苗效力或增强生物体对疫苗反应性的方法，包括在给予受试者疫苗同时、之前或之后，向所述受试者给予本发明所述的抗CD73抗体或其抗原结合片段、偶联物、融合蛋白或多特异性抗体，优选所述疫苗中包含的抗原源自病毒、细菌、真菌、立克次体、衣原体、支原体、寄生虫、朊病毒或肿瘤；
优选地，所述病毒包括RNA病毒及DNA病毒；
优选地，所述RNA病毒包括冠状病毒；
优选地，所述冠状病毒包括2019新型冠状病毒(2019-nCoV或 SARS-CoV-2，引发新型冠状病毒肺炎COVID-19)，HCoV-229E、HCoV-OC43、HCoV-NL63、HCoV-HKU1、SARS-CoV(引发重症急性呼吸综合征)和MERS-CoV(引发中东呼吸综合征)。
在一些实施方案中，所述的抗CD73抗体或其抗原结合片段、偶联物、融合蛋白或多特异性抗体被给予(优选静脉给予)单次或多次。
在本发明中，除非另有说明，否则本文中使用的科学和技术名词具有本领域技术人员所通常理解的含义。并且，本文中所用的细胞培养、分子遗传学、核酸化学、免疫学实验室操作步骤均为相应领域内广泛使用的常规步骤。同时，为了更好地理解本发明，下面提供相关术语的定义和解释。
如本文中所使用的，术语EC 50是指半最大效应浓度(concentration for 50％of maximal effect)，是指能引起50％最大效应的浓度。
如本文中所使用的，术语“抗体”是指通常由两对多肽链(每对具有一条“轻”(L)链和一条“重”(H)链)组成的免疫球蛋白分子。抗体轻链可分类为κ和λ轻链。重链可分类为μ、δ、γ、α或ε，并且分别将抗体的同种型定义为IgM、IgD、IgG、IgA和IgE。在轻链和重链内，可变区和恒定区通过大约12或更多个氨基酸的“J”区连接，重链还包含大约3个或更多个氨基酸的“D”区。各重链由重链可变区(V H)和重链恒定区(C H)组成。重链恒定区由3个结构域(C H1、C H2和C H3)组成。各轻链由轻链可变区(V L)和轻链恒定区(C L)组成。轻链恒定区由一个结构域C L组成。抗体的恒定区可介导免疫球蛋白与宿主组织或因子，包括免疫系统的各种细胞(例如，效应细胞)和经典补体系统的第一组分(C1q)的结合。V H和V L区还可被细分为具有高变性的区域(称为互补决定区(CDR))，其间散布有较保守的称为构架区(FR)的区域。各V H和V L由按下列顺序：FR1、CDR1、FR2、CDR2、FR3、CDR3、FR4从氨基末端至羧基末端排列的3个CDR和4个FR组成。各重链/轻链对的可变区(V H和V L)分别形成抗原结合部位。氨基酸至各区域或结构域的分配遵循Kabat Sequences of Proteins of Immunological Interest(National Institutes of Health，Bethesda M.d.(1987 and 1991))，或Chothia&Lesk J.Mol.Biol.1987；196：901-917；Chothia等人Nature 1989；342：878-883 或者IMGT编号系统定义，见Ehrenmann，Francois，Quentin Kaas，and Marie-Paule Lefranc.″IMGT/3Dstructure-DB and IMGT/DomainGapAlign：a database and a tool for immunoglobulins or antibodies，T cell receptors，MHC，IgSF and MhcSF.″Nucleic acids research 2009；38(suppl_1)：D301-D307.的定义。术语“抗体”不受任何特定的产生抗体的方法限制。例如，其包括，特别地，重组抗体、单克隆抗体和多克隆抗体。抗体可以是不同同种型的抗体，例如，IgG(例如，IgG1，IgG2，IgG3或IgG4亚型)，IgA1，IgA2，IgD，IgE或IgM抗体。
如本文中所使用的，术语“单抗”和“单克隆抗体”是指，来自一群高度同源的抗体分子中的一个抗体或抗体的一个片段，也即除可能自发出现的自然突变外，一群完全相同的抗体分子。单抗对抗原上的单一表位具有高特异性。多克隆抗体是相对于单克隆抗体而言的，其通常包含至少2种或更多种的不同抗体，这些不同的抗体通常识别抗原上的不同表位。单克隆抗体通常可采用Kohler等首次报道的杂交瘤技术获得(
Figure PCTCN2021112771-appb-000001
G，Milstein C.Continuous cultures of fused cells secreting antibody of predefined specificity[J].nature，1975；256(5517)：495)，但也可采用重组DNA技术获得(如参见U.S.Patent 4,816,567)。
如本文中所使用的，术语“人源化抗体”是指，人源免疫球蛋白(受体抗体)的全部或部分CDR区被一非人源抗体(供体抗体)的CDR区替换后得到的抗体或抗体片段，其中的供体抗体可以是具有预期特异性、亲和性或反应性的非人源(例如，小鼠、大鼠或兔)抗体。此外，受体抗体的构架区(FR)的一些氨基酸残基也可被相应的非人源抗体的氨基酸残基替换，或被其他抗体的氨基酸残基替换，以进一步完善或优化抗体的性能。关于人源化抗体的更多详细内容，可参见例如，Jones et al.，Nature 1986；321：522-525；Reichmann et al.，Nature 1988；332：323-329；Presta，Curr.Op.Struct.Biol.，1992；2：593-596；和Clark M.Antibody humanization：a case of the‘Emperor’s new clothes’？[J].Immunol.Today，2000；21(8)：397-402。
如本文中所使用的，术语“分离的”或“被分离的”指的是，从天然状态下经人工手段获得的。如果自然界中出现某一种“分离”的物质或成 分，那么可能是其所处的天然环境发生了改变，或从天然环境下分离出该物质，或二者情况均有发生。例如，某一活体动物体内天然存在某种未被分离的多聚核苷酸或多肽，而从这种天然状态下分离出来的高纯度的相同的多聚核苷酸或多肽即称之为分离的。术语“分离的”或“被分离的”不排除混有人工或合成的物质，也不排除存在不影响物质活性的其它不纯物质。
如本文中所使用的，术语“载体(vector)”是指，可将多聚核苷酸插入其中的一种核酸运载工具。当载体能使插入的多核苷酸编码的蛋白获得表达时，载体称为表达载体。载体可以通过转化，转导或者转染导入宿主细胞，使其携带的遗传物质元件在宿主细胞中获得表达。载体是本领域技术人员公知的，包括但不限于：质粒；噬菌粒；柯斯质粒；人工染色体，例如酵母人工染色体(YAC)、细菌人工染色体(BAC)或P1来源的人工染色体(PAC)；噬菌体如λ噬菌体或M13噬菌体及动物病毒等。可用作载体的动物病毒包括但不限于，逆转录酶病毒(包括慢病毒)、腺病毒、腺相关病毒、疱疹病毒(如单纯疱疹病毒)、痘病毒、杆状病毒、乳头瘤病毒、乳头多瘤空泡病毒(如SV40)。一种载体可以含有多种控制表达的元件，包括但不限于，启动子序列、转录起始序列、增强子序列、选择元件及报告基因。另外，载体还可含有复制起始位点。
如本文中所使用的，术语“宿主细胞”是指，可用于导入载体的细胞，其包括但不限于，如大肠杆菌或枯草杆菌等的原核细胞，如酵母细胞或曲霉菌等的真菌细胞，如S2果蝇细胞或Sf9等的昆虫细胞，或者如纤维原细胞，CHO细胞，COS细胞，NSO细胞，HeLa细胞，GS细胞，BHK细胞，HEK 293细胞或人细胞等的动物细胞。
如本文中使用的，术语“特异性结合”是指，两分子间的非随机的结合反应，如抗体和其所针对的抗原之间的反应。在某些实施方式中，特异性结合某抗原的抗体(或对某抗原具有特异性的抗体)是指，抗体以小于大约10 -5M，例如小于大约10 -6M、10 -7M、10 -8M、10 -9M或10 -10M或更小的亲和力(K D)结合该抗原。
如本文中所使用的，术语“K D”是指特定抗体-抗原相互作用的解离 平衡常数，其用于描述抗体与抗原之间的结合亲和力。平衡解离常数越小，抗体-抗原结合越紧密，抗体与抗原之间的亲和力越高。通常，抗体以小于大约10 -5M，例如小于大约10 -6M、10 -7M、10 -8M、10 -9M或10 -10M或更小的解离平衡常数(K D)结合抗原(例如，PD-1蛋白)。可以使用本领域技术人员知悉的方法测定K D，例如使用Fortebio分子相互作用仪测定。
如本文中所使用的，术语“单克隆抗体”和“单抗”具有相同的含义且可互换使用；术语“多克隆抗体”和“多抗”具有相同的含义且可互换使用；术语“多肽”和“蛋白质”具有相同的含义且可互换使用。并且在本发明中，氨基酸通常用本领域公知的单字母和三字母缩写来表示。例如，丙氨酸可用A或Ala表示。
如本文中所使用的，术语“药学上可接受的载体和/或赋形剂”是指在药理学和/或生理学上与受试者和活性成分相容的载体和/或赋形剂，其是本领域公知的(参见例如Remington′s Pharmaceutical Sciences.Edited by Gennaro AR，19th ed.Pennsylvania：Mack Publishing Company，1995)，并且包括但不限于：pH调节剂，表面活性剂，佐剂，离子强度增强剂。例如，pH调节剂包括但不限于磷酸盐缓冲液；表面活性剂包括但不限于阳离子，阴离子或者非离子型表面活性剂，例如Tween-80；离子强度增强剂包括但不限于氯化钠。
在本发明中，术语“单次药物剂量单元”表示在给药方案的时刻待给药于受试者或患者的本发明所述的抗体或其抗原结合片段、所述的抗体药物偶联物或者所述的双特异性抗体(或包含其的药物组合物)的单次药物剂型，如以一个安瓿瓶为单位。如本文中所使用的，术语“有效量”是指足以获得或至少部分获得期望的效果的量。例如，预防疾病(例如冠状病毒科病毒引起的疾病，优选新冠肺炎)有效量是指，足以预防，阻止，或延迟疾病的发生的量；治疗疾病有效量是指，足以治愈或至少部分阻止已患有疾病的患者的疾病和其并发症的量。
发明的有益效果：
本发明的单克隆抗体能够很好地特异性与CD73结合，并且能够十 分有效地、以非底物竞争的方式抑制CD73的酶活反应，诱导细胞表面CD73的内吞，进而降低腺苷的产生；尚可以以腺苷非依赖方式刺激B细胞活化与增殖。
附图说明
图1. 19F3H2L3诱导后B细胞CD69的MFI值。
图2. 19F3H2L3诱导后B细胞CD83的MFI值。
图3.MDA-MB-231细胞中加入抗CD73抗体的酶活性的检测结果。
图4.U87-MG细胞中加入抗CD73抗体的酶活性的检测结果。
图5.MDA-MB-231细胞中加入抗CD73抗体诱导细胞膜表面CD73内吞的检测结果，其中图5A表示MFI值，图5B为内化率。
图6.U87-MG细胞中加入抗CD73抗体诱导细胞膜表面CD73内吞的检测结果，其中图6A表示MFI值，图6B为内化率。
图7.抗CD73抗体有效诱导针对新冠肺炎S蛋白的抗体生成检测结果。
图8.FACS检测抗CD73抗体19F3H2L3(hG1DM)与CD8+T细胞、CD19+B细胞的结合活性检测结果。
图9.抗CD73抗体19F3H2L3(hG1DM)抑制人PBMC膜表达CD73的酶活活性检测结果。
图10.FACS检测抗CD73抗体19F3H2L3(hG1DM)有效诱导B细胞活化检测结果。
图11.抗CD73抗体19F3H2L3(hG1DM)刺激B细胞增殖检测结果。
具体实施方式
下面将结合实施例对本发明的实施方案进行详细描述。本领域技术人员将会理解，下面的实施例仅用于说明本发明，而不应视为限定本发明的范围。实施例中未注明具体技术或条件者，按照本领域内的文献所描述的技术或条件(例如参考J.萨姆布鲁克等著，黄培堂等译的《分子克隆实验指南》，第三版，科学出版社)或按照产品说明书进行。所用试剂或仪器未注明生产厂商者，为可以通过市场购买获得的常规产品。例如MDA-MB-231细胞和U87-MG细胞可以购自ATCC。
在本发明的下述实施例中，使用的BALB/c小鼠购自广东省医学实验动物中心。
在本发明的下述实施例中，所用的阳性对照抗体MEDI9447(Oleclumab)，生产自中山康方生物医药有限公司，其序列与Medlmmune Limited在WHO药物信息数据库及相关专利中所公开的Oleclumab氨基酸序列所构建合成的(https：//www.who.int/medicines/publications/drμginformation/innlists/en/)，实施例中标记为MEDI9447或者MEDI9447(Akeso)或者MEDI-9447(Akeso)；
在本发明的下述实施例中，所用的对照抗体CPI-006，药品通用名为Mupadolimab，生产自中山康方生物医药有限公司，其序列来源与WHO，WHO Drug Information，Proposed INN：List 125.2021，35(2)：484-485.中序列一致。CPI-006(Mupadolimab)重链氨基酸序列如SEQ ID NO：21所示，CPI-006轻链氨基酸序列如SEQ ID NO：22所示。
在本发明的下述实施例中，所用的同型对照抗体为人抗鸡蛋溶酶体抗体(human anti-Hen Egg Lysozyme IgG，即anti-HEL抗体，或者human IgG，简称hIgG，或者同型对照)的序列来自于Acierno等人发表的Affinity maturation increases the stability and plasticity of the Fv domain of anti-protein antibodies中Fab F10.6.6序列的可变区序列(Acierno等人.J Mol Biol.2007；374(1)：130-146.)；实施例中所用到的hIgG1DM是anti-HEL带有hG1DM恒定区序列的同型对照抗体，在中山康方生物医药有限公司实验室制备而成。
在本发明的下述实施例中，所用的正常人外周血来源于中山血站，人外周血细胞均为在中山康方生物医药有限公司分离制备，且经提供者知情同意；
在本发明的下述实施例中，所用的FITC标记抗人CD3抗体来源于Biolegend，货号：344804；所用的PE标记抗人CD19抗体来源于Biolegend，货号：302254；所用的APC标记抗人CD69抗体来源于Biolegend，货号：310910；所用的APC标记抗人CD83抗体来源于 Biolegend，货号：305312；所用的吖啶橙染色液来源于Thermofisher，货号：93001；所用的碘化丙啶染色液来源于BD，货号：51-66211E；所用的APC标记小鼠IgG1同型对照抗体来源于Biolegend，货号：400122；所用的小鼠IgG1同型对照抗体来源于Thermofisher，货号：10400C；所用的牛血清白蛋白(BSA)来源于Sigma，货号：V900933-1KG；所用的RPMI 1640来源于Gibco，货号：22400-089；所用的胎牛血清来源于Excell bio，货号：FSP500；所用的丙酮酸钠来源于Gibco，货号：11360-070；所用的非必需氨基酸来源于Gibco，货号：11140-050；所用的L-谷氨酰胺来源于Gibco，货号：25030-081；所用的MDA-MB-231来源于ATCC，货号：HTB-26；所用的U87-MG来源于ATCC，货号：HTB-14；所用的CTG显色液为
Figure PCTCN2021112771-appb-000002
One Solution Assay试剂盒，来源于promega，货号：G8461；所用的Alexa
Figure PCTCN2021112771-appb-000003
647标记鼠抗人IgG二抗来源于Southern Biotech，货号：9040-31。
实施例1：抗CD73抗体19F3的制备
1.杂交瘤细胞株LT014的制备
制备抗CD73抗体所用的抗原为人NT5E-His(NT5E为GenbankID：NP_002517.1，位置：1-552)。取免疫后的小鼠的脾细胞与小鼠骨髓瘤细胞融合，制成杂交瘤细胞。以人NT5E(NT5E为GenbankID：NP_002517.1，位置：1-552)-Biotin作为抗原，对杂交瘤细胞进行间接ELISA法筛选，获得能够分泌与CD73特异性结合的抗体的杂交瘤细胞。对筛选得到的杂交瘤细胞，经过有限稀释法得到稳定的杂交瘤细胞株。将以上杂交瘤细胞株分别命名为杂交瘤细胞株LT014，其分泌的单克隆抗体分别命名为19F3。
杂交瘤细胞株LT014(又称CD73-19F3)，其于2018年6月21日保藏于中国典型培养物保藏中心(CCTCC)，保藏编号为CCTCC NO：C2018137，保藏地址为中国.武汉.武汉大学，邮编：430072。
2.抗CD73抗体19F3的制备
用CD培养基(Chemical Defined Medium)对上面制得的LT014细胞 株分别进行培养(CD培养基，内含1％青链霉素，于5％CO 2，37℃细胞培养箱中进行培养)。7天后收集细胞培养上清，通过高速离心、微孔滤膜抽真空过滤，并使用HiTrap protein A HP柱进行纯化，分别制得抗体19F3。
实施例2：抗CD73的抗体19F3的序列分析
按照培养细胞细菌总RNA提取试剂盒(Tiangen，货号DP430)的方法，从实施例1中培养的LT014细胞株中提取mRNA。
按照Invitrogen
Figure PCTCN2021112771-appb-000004
III First-Strand Synthesis System for RT-PCR试剂盒说明书合成cDNA，并进行PCR扩增。
PCR扩增产物直接进行TA克隆，具体操作参考pEASY-T1 Cloning Kit(Transgen CT101)试剂盒说明书进行。
将TA克隆的产物直接进行测序，测序结果如下：
重链可变区的核酸序列如SEQ ID NO：1所示，长度为363bp。
其编码的氨基酸序列如SEQ ID NO：2所示，长度为121aa；
其中重链CDR1的序列如SEQ ID NO：15所示，重链CDR2的序列如SEQ ID NO：16所示，重链CDR3的序列如SEQ ID NO：17所示。
轻链可变区的核酸序列如SEQ ID NO：3所示，长度为339bp。
其编码的氨基酸序列如SEQ ID NO：4所示，长度为113aa；
其中轻链CDR1的序列如SEQ ID NO：18所示，轻链CDR2的序列如SEQ ID NO：19所示，轻链CDR3的序列如SEQ ID NO：20所示。
实施例3：抗人CD73的人源化抗体的轻链和重链设计和制备
1.抗人CD73的人源化抗体19F3H1L1、19F3H2L2和19F3H2L3的轻链和重链设计
根据人CD73蛋白的三维晶体结构(Hage T，Reinemer P，Sebald W.Crystals of a 1∶1 complex between human interleukin-4 and the extracellular domain of its receptor alpha chain.Eur J Biochem.1998；258(2)：831-6.)以及实施例2获得的抗体19F3的序列，通过计算机模拟抗体模型，根据模型设计突变，得到抗体19F3H1L1、19F3H2L2、19F3H2L3的可变区序列(抗 体恒定区序列，来自NCBI的数据库，重链恒定区均采用Ig gamma-1 chain C region，ACCESSION：P01857；轻链恒定区为Ig kappa chain C region，ACCESSION：P01834)。
设计的可变区序列如下：
(1)人源化单克隆抗体19F3H1L1的重链可变区和轻链可变区序列
重链可变区的核酸序列如SEQ ID NO：5所示，长度为363bp。
其编码的氨基酸序列如SEQ ID NO：6所示，长度为121aa，其中重链CDR1的序列如SEQ ID NO：15所示，重链CDR2的序列如SEQ ID NO：16所示，重链CDR3的序列如SEQ ID NO：17所示。
轻链可变区的核酸序列如SEQ ID NO：7所示，长度为339bp。
其编码的氨基酸序列如SEQ ID NO：8所示，长度为113aa，其中轻链CDR1的序列如SEQ ID NO：18所示，轻链CDR2的序列如SEQ ID NO：19所示，轻链CDR3的序列如SEQ ID NO：20所示。
(2)人源化单克隆抗体19F3H2L2的重链可变区和轻链可变区序列
重链可变区的核酸序列如SEQ ID NO：9所示，长度为363bp。
其编码的氨基酸序列如SEQ ID NO：10所示，长度为121aa，其中重链CDR1的序列如SEQ ID NO：15所示，重链CDR2的序列如SEQ ID NO：16所示，重链CDR3的序列如SEQ ID NO：17所示。
轻链可变区的核酸序列如SEQ ID NO：11所示，长度为339bp。
其编码的氨基酸序列如SEQ ID NO：12所示，长度为113aa，其中轻链CDR1的序列如SEQ ID NO：18所示，轻链CDR2的序列如SEQ ID NO：19所示，轻链CDR3的序列如SEQ ID NO：20所示。
(3)人源化单克隆抗体19F3H2L3的重链可变区和轻链可变区序列
重链可变区的核酸序列如SEQ ID NO：9所示，长度为363bp。
其编码的氨基酸序列如SEQ ID NO：10所示，长度为121aa，其中重链CDR1的序列如SEQ ID NO：15所示，重链CDR2的序列如SEQ ID NO：16所示，重链CDR3的序列如SEQ ID NO：17所示。
轻链可变区的核酸序列如SEQ ID NO：13所示，长度为339bp。
其编码的氨基酸序列如SEQ ID NO：14所示，长度为113aa，其中轻链CDR1的序列如SEQ ID NO：18所示，轻链CDR2的序列如SEQ ID NO：19 所示，轻链CDR3的序列如SEQ ID NO：20所示。
3.人源化抗体19F3H1L1、19F3H2L2和19F3H2L3的制备
重链恒定区均采用Ig gamma-1 chain C region，ACCESSION：P01857；轻链恒定区均采用Ig kappa chain C region，ACCESSION：P01834。
将19F3H1L1重链cDNA和轻链的cDNA、19F3H2L2重链cDNA和轻链的cDNA、以及19F3H2L3的重链cDNA和轻链的cDNA，分别克隆到pUC57simple(金斯瑞公司提供)载体中，分别获得pUC57simple-19F3H1、pUC57simple-19F3L1；pUC57simple-19F3H2、pUC57simple-19F3L2和pUC57simple-19F3L3。参照《分子克隆实验指南(第二版)》介绍的标准技术，EcoRI&HindIII酶切合成的重、轻链全长基因，通过限制酶(EcoRI&HindIII)的酶切亚克隆到表达载体pcDNA3.1中获得表达质粒pcDNA3.1-19F3H1，pcDNA3.1-19F3L1，pcDNA3.1-19F3H2，pcDNA3.1-19F3L2，和pcDNA3.1-19F3L3，并进一步对重组表达质粒的重/轻链基因进行测序分析。随后将含有相应的轻、重链重组质粒设计基因组合(pcDNA3.1-19F3H1/pcDNA3.1-19F3L1，pcDNA3.1-19F3H2/pcDNA3.1-19F3L2，和pcDNA3.1-19F3H2/pcDNA3.1-19F3L3)分别共转染293F细胞后收集培养液进行纯化。测序验证正确后，制备去内毒素级别的表达质粒并将质粒瞬时转染HEK293细胞进行抗体表达，培养7天后收集细胞培养液，采用Protein A柱进行亲和纯化获得人源化抗体。
4.人源化抗体19F3H2L3(hG1DM)的制备
19F3H2L3(hG1DM)的抗体的轻链恒定区为Ig kappa链C区，ACCESSION：P01834，见SEQ ID NO：22。
重链恒定区在Ig gamma-1 chain C region，ACCESSION：P01857的基础上，在第234号位点引进了亮氨酸到丙氨酸的点突变(L234A)，第235号位点引进了亮氨酸到丙氨酸的点突变(L235A)，获得了命名为19F3H2L3(hG1DM)的人源化抗体，19F3H2L3(hG1DM)的重链氨基酸全长序列见SEQ ID NO：23，19F3H2L3(hG1DM)的轻链氨基酸全长序列见SEQ ID NO：24。
将19F3H2L3(hG1DM)的重链cDNA和轻链的cDNA，分别克隆到pUC57simple(金斯瑞公司提供)载体中，分别获得pUC57simple-19F3H2(hG1DM)和pUC57simple-19F3L3。参照《分子克隆实验指南(第二版)》介绍的标准技术，EcoRI&HindIII酶切合成的重、轻链全长基因，通过限制酶(EcoRI&HindIII)的酶切亚克隆到表达载体pcDNA3.1中获得表达质粒pcDNA3.1-19F3H2(hG1DM)和pcDNA3.1-19F3L3，并进一步对重组表达质粒的重/轻链基因进行测序分析。随后将含有相应的轻、重链重组质粒设计基因组合(pcDNA3.1-19F3H2(hG1DM)/pcDNA3.1-19F3L3)分别共转染293F细胞后收集培养液进行纯化。测序验证正确后，制备去内毒素级别的表达质粒并将质粒瞬时转染HEK293细胞进行抗体表达，培养7天后收集细胞培养液，采用Protein A柱进行亲和纯化获得人源化抗体。
实施例4：抗CD73抗体有效诱导B活化
CD69是一种C型跨膜糖蛋白，往往表达于活化后的T、B、NK等淋巴细胞表面，通常作为淋巴细胞早期活化的标记物。CD83是另一种早期活化标记物，不仅广泛表达于成熟DC，在活化的免疫细胞如B淋巴细胞亦有表达，可阻止MHC II类和CD86分子在细胞表面的降解，参与免疫调节。B细胞活化后可成为记忆B细胞或者浆细胞分泌抗体及细胞因子，参与对病毒等外源微生物感染的免疫反应。
本试验以CD69和CD83作为B细胞活化的分子标记，CD69和CD83的MFI值和阳性率与B细胞活化活性呈正相关。
实验步骤：按照分离液Ficoll-PaqueTM Plus试剂说明书分离健康人外周血PBMC，分离后的PBMC冻存备用。实验当天常规复苏PBMC，重悬于完全培养基(RPMI 1640+10％FBS+1％丙酮酸钠+1％非必需氨基酸+1％L-谷氨酰胺)，按240*10 4细胞/500μL/孔接种至12孔板，加入500μL相应抗体浓度溶液，每组2个复孔，培养过夜；次日，完全吹散孔内细胞，各组均分为5个孔，750*g离心5min收集细胞，每孔加入100μL小鼠IgG同型对照抗体(终浓度为5μg/mL)，冰上孵育20min，750*g离心5min去上清，各组每孔分别对应加入100μL以下二抗：FITC标记抗人CD3抗体 (50倍稀释)、PE标记抗人CD19抗体(50倍稀释)、APC标记抗人CD69抗体(100倍稀释)、APC标记抗人CD83抗体(50倍稀释)、APC标记小鼠IgG1同型对照抗体(100倍稀释)，置于冰上避光孵育40min，每孔加入100μL 1％PBSA(含1％BSA的PBS)，750*g离心5min去上清，200μL/管1％PBSA重悬细胞沉淀并转移至流式管，流式细胞仪(FACS Calibur)上机检测。
Flowing软件做流式直方图和散点图，并分析CD3-CD19+细胞亚群中CD69和CD83表达的MFI值，根据对应MFI值用Graphpad prism软件以平均值±标准差SD做图并进行单因素方差分析，P＜0.05有显著性差异，P＜0.01有非常显著性差异。
结果如图1、图2所示，与同型对照相比，19F3H2L3处理组CD69和CD83的MFI值明显上升，表明19F3H2L3可诱导B细胞活化，上调CD69和CD83的表达，活性优于同靶点临床在研对照抗体MEDI9447。而CD73酶活抑制剂APCP(Sigma，货号：M3763-10MG)对B细胞表面CD69和CD83的表达无影响，表明19F3H2L3可通过不同于CD73酶活抑制的信号通路诱导B细胞的活化。
本试验检测结果显示19F3H2L3可显著上调B细胞(CD3-CD19 +)表面CD69和CD83的表达，表明19F3H2L3具有诱导B细胞活化的生物学活性，且该活性显著优于同靶点临床在研对照抗体MEDI9447；同时，检测结果显示CD73酶活抑制剂APCP对B细胞表面CD69和CD83的表达无影响，表明19F3H2L3可通过不同于CD73酶活抑制的信号通路诱导B细胞的活化，从而促进对病毒等抗原的免疫应答。抗体19F3，抗体19F3H1L1和抗体19F3H2L2实现类似效果。
实施例5：抗CD73抗体对抑制细胞内源表达CD73酶活性的检测
1、抗CD73抗体对MDA-MB-231细胞内源表达CD73酶活性的抑制活性检测
实验步骤如下：取状态良好的对数期MDA-MB-231细胞，用无血 清的RPMI-1640培养液将细胞重悬、计数；将MDA-MB-231细胞接种至96孔板，3*10 4个细胞/100μl/孔；用无血清RPMI-1640培养液稀释抗体，起始浓度200μg/ml，按2.5倍进行梯度稀释；将抗体加入96孔板，每孔50μl，37℃孵育1小时。1小时后，每孔加入50μl RPMI-1640稀释的600μM AMP；3小时后取25μl细胞培养液上清，转移至新96孔板，每孔加入25μl 100μM的ATP；和50μl CTG(
Figure PCTCN2021112771-appb-000005
One Solution Assay，promega，Cat：G8461)显色液，进行显色，多标记微孔板检测仪(PerkinElmer 2140-0020)读取数据。
实验结果：结果如图3所示，19F3H2L3和同靶点阳性对照药MEDI9447均可呈剂量依赖性抑制MDA-MB-231内源表达的CD73酶催化AMP为腺苷A的活性，从而剂量依赖性降低产生的平均荧光强度RLU。
以上实验结果说明加入的AMP在无CD73抗体处理情况下，可被MDA-MB-231内源表达于细胞表面的CD73酶催化而转化为腺苷，从而解除对荧光素酶活性的抑制。而加入抗体后，由于CD73被抗体结合，而降低了其酶催化活性，使AMP不能转化为腺苷。提示抗CD73抗体以非底物竞争的方式有效抑制CD73的酶活反应，降低腺苷的产生。
2、在U87-MG细胞中加入抗CD73抗体的酶活性的检测
实验步骤如下：取状态良好的对数期U87-MG细胞，用无血清的RPMI-1640培养液将细胞重悬、计数；将U87-MG细胞接种至96孔板，3*10 4个细胞/100μl/孔；用无血清RPMI-1640培养液稀释抗体，起始浓度200μg/ml，按2.5倍进行梯度稀释；将抗体加入96孔板，每孔50μl，37℃孵育1小时；1小时后，每孔加入50μl RPMI-1640稀释的600μM AMP；3小时后取25μl细胞培养液上清，转移至新96孔板，每孔加入25μl 100μM的ATP和50μl CTG
Figure PCTCN2021112771-appb-000006
One Solution Assay，promega，Cat：G8461)显色液，进行显色，于多标记微孔板检测仪(PerkinElmer 2140-0020)读取数据。
实验结果：结果如图4所示，19F3H2L3和同靶点阳性对照药MEDI9447均可呈剂量依赖性抑制MDA-MB-231内源表达的CD73酶 催化AMP为腺苷的活性，从而剂量依赖性降低产生的平均荧光强度RLU(Relative Light Unit)。
以上实验结果说明加入的AMP在无CD73抗体处理情况下，可被U87-MG内源表达于细胞表面的CD73酶催化而转化为腺苷，从而解除对荧光素酶活性的抑制。而加入抗体后，由于CD73被抗体结合，而降低了其酶催化活性，使AMP不能转化为腺苷。提示抗CD73抗体以非底物竞争的方式有效抑制CD73的酶活反应，降低腺苷的产生。抗体19F3，抗体19F3H1L1和抗体19F3H2L2实现类似效果。
实施例6：抗CD73抗体有效诱导细胞膜表面表达CD73的内化
本试验采用FACS法评价了19F3H2L3介导MDA-MB-231细胞、U87-MG细胞膜表面CD73内化的生物学活性。间接内化法MFI(Mean Fluorescence Intensity，平均荧光强度)值与内吞活性负相关。
实验步骤：完全培养基培养细胞至对数期，170xg，5min收集细胞，细胞计数及活率，30w/样本。按实验设计加入相应浓度稀释的抗体溶液，每管100μL，并设计空白及同型对照，冰上孵育1h；加入1000μL 1％PBSA，1200xg，离心5min，弃上清，重复洗涤1次。每管加入相应200μL的完全培养基，37℃进行不同时间段的内吞。内吞完后，1000μL 1％PBSA(含0.05％叠氮钠，SIGMA，货号：S2002-25G)，1200xg，离心5min。每管加入相应100μL的荧光二抗，混匀后冰上避光孵育40min。加入1000μL 1％PBSA(含0.05％叠氮钠)，1200xg，离心5min，弃上清。200μL 1％PBSA(含0.05％叠氮钠)/管，重悬细胞，转移至流式上样管，上机测试。
内化结果如图5和图6所示。19F3H2L3与MDA-MB-231、U87-MG细胞在37℃孵育0.5小时后，即可明显观察到MFI值减弱(参见图5A和图6A)，表明19F3H2L3可快速介导细胞膜表面CD73的内化。在MDA-MB-231细胞，孵育22小时后，19F3H2L3介导的内化率可达60.75％，同靶点对照药MEDI9447介导的后内化率为50.53％，较19F3H2L3低10.22％(参见图6B)；在U87-MG细胞，22小时后， 19F3H2L3介导的CD73内化率为82.39％，同靶点对照抗体MEDI9447的22小时后内化率为73.65％，较19F3H2L3低8.74％(参见图5B)。抗体19F3，抗体19F3H1L1和抗体19F3H2L2实现类似效果。
实施例7：ELISA方法测定抗CD73抗体与抗原人NT5E-Biotin的结合活性
实验步骤：将链霉亲和素，2μg/ml包被酶标板后，4℃孵育12小时。孵育结束后使用PBST漂洗包被了抗原的酶标板1次，后使用1％BSA的PBST溶液作为酶标板封闭液，封闭2小时。酶标板结束封闭后用PBST洗板3次。再加入抗原人NT5E-Biotin(中山康方生物医药有限公司制备，批号：20160505)0.5μg/ml，置于37℃条件下孵育30分钟后用PBST洗板3次。在酶标板孔内加入PBST溶液梯度稀释的抗体，抗体稀释梯度详见表1。加入待测抗体的酶标板置于37℃条件下孵育30分钟，孵育完成后用PBST洗板3次。洗板后加入1∶5000比例稀释的HRP标记羊抗人IgG(H+L)(Jackson，货号：109-035-088)或者1∶5000比例稀释的HRP标记羊抗鼠IgG(H+L)(Jackson，货号：115-035-062)二抗工作液，置于37℃条件下孵育30分钟。孵育完成后使用PBST洗板4次，后加入TMB(Neogen，308177)避光显色5min，加入终止液终止显色反应。立即把酶标板放入酶标仪中，选择450nm光波长读取酶标板各孔的OD数值。用SoftMax Pro 6.2.1软件对数据进行分析处理。
检测抗CD73抗体与抗原人NT5E-Biotin结合的各剂量的OD值见表1。以抗体浓度为横坐标，吸光度值为纵坐标进行曲线拟合，计算抗体的结合EC 50，结果如下表1所示。
实验结果显示，抗体19F3H1L1、19F3H2L2、19F3H2L3以及鼠源抗体19F3均能有效与人NT5E-Biotin结合，结合效率呈剂量依赖关系。在基本相同的实验条件下，19F3H1L1与人NT5E-Biotin结合的EC 50为0.049nM，19F3H2L2与人NT5E-Biotin结合的EC 50为0.064nM，19F3 H2L3与人NT5E-Biotin结合的EC 50为0.061nM，同靶点阳性药MEDI9447与人NT5E-Biotin结合的EC 50为0.048nM，以及鼠源抗体19F3与人NT5E-Biotin结合的EC 50为0.018nM，
以上实验结果表明，在相同实验条件下19F3H1L1、19F3H2L2、19F3H2L3以及鼠源抗体19F3分别与人NT5E-Biotin的结合活性与同靶点阳性药MEDI9447相当，提示19F3H1L1、19F3H2L2、19F3H2L3具有有效结合CD73的功能。
表1 19F3H1L1、19F3H2L2、19F3H2L3和鼠源19F3与HNT5E-Biotin的结合活性检测结果
Figure PCTCN2021112771-appb-000007
实施例8：抗CD73抗体有效诱导针对新冠肺炎S蛋白的抗体生成
1.实验材料：
hIgG1DM，中山康方生物医药有限公司生产；S蛋白(nCoV_SRBD-mFc，序列参见YP_009724390.1)，中山康方生物医药有限公司生产；CFA(费氏完全佐剂)，购自SIGMA，货号：F5881-10ml；IFA(费氏不完全佐剂)，购自SIGMA，货号：F5506-10ml。
2.实验方法：
实验方案和给药方案如下表所示。
表2.抗CD73抗体有效诱导针对新冠肺炎S蛋白的抗体生成实验方案
Figure PCTCN2021112771-appb-000008
Figure PCTCN2021112771-appb-000009
注：IP：腹腔注射；BIW*6：一周给药两次，总共给药6次
3.实验结果：
如图7所示。模型组中，小鼠接受S蛋白(25μg/只)+佐剂诱导注射后，小鼠血清中针对S蛋白特异性IgG水平增加，提示S蛋白(25μg/只)+佐剂可有效诱导机体针对新冠病毒S蛋白的免疫反应。19F3H2L3(hG1DM)给药组小鼠血清中S蛋白特异性IgG与同型对照相比有不同程度的增加，其中第51天19F3H2L3(hG1DM)高低剂量组与同型对照高低剂量组相比具有统计学差异(T-test)，19F3H2L3(hG1DM)低剂量(10mg/kg)促进小鼠分泌S蛋白特异性IgG效果更为显著。抗体19F3，抗体19F3H1L1和抗体19F3H2L2实现类似效果。
实施例9：FACS检测抗CD73抗体19F3H2L3(hG1DM)与CD8+T细胞、CD19+B细胞的结合活性
实验步骤如下：复苏PBMC，1200rpm下离心5min，弃上清，重悬于完全培养基，计数，37℃培养过夜。1200rpm下离心5min，收集细胞，加入100μL/孔稀释好的抗体溶液，混匀，置于4℃冰箱孵育1小时。750xg下离心5min，弃上清，200μL 1X PBS(含1％BSA和0.05％NaN3)洗涤2次。加入anti-human CD3-FITC(2μL/100μL)、anti-human CD19-PE(2μL/100μL)(Biolegend，货号：302254)、anti-human CD8-PerCP Cy5.5(1μL/100μL)、anti-human IgG Fc-AF647(1∶300)(Southern Biotech，货号：9040-31)，4℃孵育30min。750xg下离心5min，弃上清，200μL 1X PBS(含1％BSA和0.05％NaN3)洗涤1次；300μL 1X PBS(含1％BSA和0.05％NaN3)重悬，转移至流式管，上机检测。
结果如图8和表3所示，抗CD73抗体19F3H2L3(hG1DM)、阳性对照抗体CPI-006与CD8+T细胞的结合活性EC50(nM)分别为0.087nM、0.288nM，抗CD73抗体19F3H2L3(hG1DM)、阳性对照抗体CPI-006与CD19+B细胞的结合活性EC50(nM)分别为0.018nM、0.108nM。19F3H2L3(hG1DM)和同靶点阳性对照药CPI-006均可呈剂量依赖性结合人CD8 +T和CD19 +B细胞表达的CD73，从而剂量依赖性增加产生的平均荧光强度MFI(Mean Fluorescence Intensity)。
以上结果说明，在相同实验条件下19F3H2L3(hG1DM)与CD8+T细胞、CD19+B细胞结合能力要强于阳性对照抗体CPI-006。
表3：FACS检测抗CD73抗体与CD8+T细胞、CD19+B细胞的结合活性
Figure PCTCN2021112771-appb-000010
实施例10：抗CD73抗体19F3H2L3(hG1DM)抑制人PBMC膜表达CD73的酶活活性
实验步骤如下：梯度密度离心法分离新鲜人PBMC，重悬于分析培养基(不含血清的RPMI-1640)。计细胞数及活率，按10*10 4个细胞/孔 接种至96孔板，60μL/孔。用分析培养基将抗体稀释至以下浓度：30、10、3.3、1.1、0.11、0.011、0.0011、0.00011μg/mL，将抗体加入96孔板中，60μL/孔，与细胞轻柔混匀，置于37℃培养箱孵育30min。用分析培养基配制浓度为60μM的AMP溶液(TCI，Cat.A0158)，备用；用TM buffer(akesobio，20191009)配制浓度为30μM的ATP溶液，备用。细胞抗体孵育30min后，加入配制好的AMP溶液，60μL/孔，轻柔混匀，置于37℃培养箱孵育过夜(10h)。孵育过夜完毕前，取出一块洁净的96孔黑板，加入CTG(promega，Cat：G8461)，40μL/孔；孵育过夜完毕后，取出培养箱中的96孔板，750xg下离心5min，并按每孔100μL将上清液转移至已加有CTG的96孔黑板中，轻拍，室温避光放置5min。5min后，向96孔黑板加入配制好的ATP溶液，10μL/孔，轻拍混匀，室温避光放置15min。15min后，用Envision酶标仪检测RLU值。
实验结果：结果如图9和表4所示，19F3H2L3(hG1DM)、MEDI9447、CPI-006抑制人PBMC膜表达CD73的酶活活性效率EC50(nM)分别为0.033nM、0.0064nM、0.2258nM。19F3H2L3(hG1DM)和同靶点阳性对照药MEDI9447、CPI-006均可呈剂量依赖性抑制人PBMC表达的CD73酶催化AMP为腺苷的活性，从而剂量依赖性降低产生的平均荧光强度。并且抗CD73抗体19F3H2L3(hG1DM)的抑制率要强于阳性对照药MEDI9447、CPI-006。
表4：抗CD73抗体抑制人PBMC膜表达CD73的酶活活性
抗体名称 MEDI9447 CPI-006 19F3H2L3(hG1DM)
抑制率EC50(nM) 0.0064 0.2258 0.0330
R2 0.9984 0.9986 0.9997
实施例11：FACS检测抗CD73抗体19F3H2L3(hG1DM)有效诱导B细胞活化
CD69是一种C型跨膜糖蛋白，往往表达于活化后的T、B、NK等淋巴细胞表面，通常作为淋巴细胞早期活化的标记物。CD83是另一种早期活化标记物，不仅广泛表达于成熟DC，在活化的免疫细胞如B淋巴细胞亦有表达，可阻止MHC II类和CD86分子在细胞表面的降解，参与免疫 调节。B细胞活化后可成为记忆B细胞或者浆细胞分泌抗体及细胞因子，参与对病毒等外源微生物感染的免疫反应。激活的B细胞会产生以IgM为主的抗体。HLA-DR是MHC-II类分子，于B细胞上有表达，HLA-DR表达量的增加是B淋巴细胞活化的标志。因此本试验以CD69、CD83、HLA-DR、IgM作为B细胞活化的分子标记，CD69、CD83、HLA-DR、IgM的MFI值和阳性率与B细胞活化活性呈正相关。
实验步骤如下：
复苏B细胞，重悬于完全培养基，计数，接种于96孔板中10万个/100μL/孔，每组设置2个复孔；加入抗体或APCP(α，β-亚甲基腺苷5′-二磷酸，Sigma，货号：M3763-10MG)，混匀，置于培养箱孵育；(加有50μL hIgG1(Akesobio，批号：20170424)实验孔先与B细胞孵育30min后在加入50μL相应抗体浓度溶液)分别于孵育4h和3天后，收集B细胞，流式细胞术检测CD3-CD19+B细胞CD69/CD83/HLA-DR/IgM表达水平。
FACS操作步骤：轻柔混匀孔板内各孔B细胞，并均分转移至96孔板5个孔，750xg，5min去上清，PBSA(含1％BSA的PBS)重悬，加入小鼠IgG(Mouse IgG Isotype Control)100μl/孔，终浓度为5μg/ml，冰上孵育20min，750xg，5min弃上清，分别加入Mix1/2/3/4/5/6/7。
Mix1：100uL PBSA；
Mix2：100μl PBSA中含有2μl FITC anti-human CD3(购自Biolegend，货号：344804)+2μl PE anti-human CD19(购自Biolegend，货号：302254)；
Mix3：100μl PBSA中含有2μl FITC anti-human CD3+2μl PE anti-human CD19+1μl APC anti-human CD69(购自Biolegend，货号：310910)；
Mix4：100μl PBSA中含有2μl FITC anti-human CD3+2μl PE anti-human CD19+2μl APC anti-human CD83(购自Biolegend，货号：305312)；
Mix5：100μl PBSA中含有2μl FITC anti-human CD3+2μl PE anti-human CD19+2μl APC anti-human HLA-DR(购自Biolegend，货号：361610)；
Mix6：100μl PBSA中含有2μl FITC anti-human CD3+2μl PE anti-human CD19+2μl APC anti-human IgD(购自Biolegend，货号：348222)+2μl PerCP/Cyanine5.5 anti-human CD27抗体(Biolegend，货号：356408)；
Mix7：100μl PBSA中含有2μl FITC anti-human CD3+2μl PE anti-human  CD19+2μl APC anti-human IgM(购自Biolegend，货号：314510)。
冰上孵育40min，加入200μL PBSA/孔，750xg，5min离心洗涤；加入200μL PBSA/孔，重悬细胞，上机测试。
结果如图10所示，与同型对照相比，19F3H2L3(hG1DM)处理组CD69、CD83、HLA-DR、IgM的MFI值明显上升，表明19F3H2L3(hG1DM)可诱导B细胞活化，上调CD69、CD83、HLA-DR、IgM的表达，活性优于同靶点临床在研对照抗体MEDI9447和CPI-006。而CD73酶活抑制剂APCP(Sigma，货号：M3763-10MG)对B细胞表面CD69、CD83、HLA-DR、IgM的表达无影响，表明19F3H2L3(hG1DM)可通过不同于CD73酶活抑制的信号通路诱导B细胞的活化。
实施例12：抗CD73抗体19F3H2L3(hG1DM)刺激B细胞增殖
实验步骤如下：复苏PBMC，250xg离心5min，完全培养基重悬，计数。离心弃掉完全培养基，RPMI-1640洗涤一次，并重悬。加入0.25μM CFSE(Biolegend，货号：423801)溶液到1×10 6个细胞/mL，37℃培养箱避光孵育2min；加入2到3倍含血清培养基终止，250xg(1200rpm)离心5min弃上清；用RPMI-1640完全培养基将细胞重悬，计数，24孔板中加入2.4*10 6个细胞/孔的细胞悬液，按实验设计每孔加入相应浓度的抗体溶液，37℃、5％CO 2的二氧化碳培养箱中孵育7天。24孔板均在D3天时弃一半上清，补加含完全培养基稀释的相应浓度抗体溶液，继续培养至D6天时，24孔板均在D6天时弃一半上清，补加含完全培养基稀释的相应浓度抗体溶液，继续培养至D7天时，24孔板均收细胞，按下面步骤进行流式标记上机。1200xg离心5min，收集细胞，取得相应的细胞数分组跟5μg/mL MS mouse IgG(Thermofisher，货号：10400C)孵育20min；离心洗涤，加入相应的荧光抗体孵育60min。重悬于1％PBSA，转移至流式管上机检测。
结果如图11所示，人PBMC加入不同抗体处理7天后，与人IgG1DM相比，MEDI9447处理组未见B细胞增殖，而19F3H2L3浓度低至0.05μg/mL即可显著促进B细胞增殖。抗体19F3，抗体19F3H1L1和抗体19F3H2L2实现类似效果。
序列表
中山康方生物医药有限公司
发明名称：抗CD73的抗体及其用途
19F3重链可变区的核酸序列：(SEQ ID NO：1)
Figure PCTCN2021112771-appb-000011
19F3重链可变区的氨基酸序列：(SEQ ID NO：2)
Figure PCTCN2021112771-appb-000012
19F3轻链可变区的核酸序列：(SEQ ID NO：3)
Figure PCTCN2021112771-appb-000013
19F3轻链可变区的氨基酸序列：(SEQ ID NO：4)
Figure PCTCN2021112771-appb-000014
19F3H1L1重链可变区的核酸序列：(SEQ ID NO：5)
Figure PCTCN2021112771-appb-000015
19F3H1L1重链可变区的氨基酸序列：(SEQ ID NO：6)
Figure PCTCN2021112771-appb-000016
19F3H1L1轻链可变区的核酸序列：(SEQ ID NO：7)
Figure PCTCN2021112771-appb-000017
19F3H1L1轻链可变区的氨基酸序列：(SEQ ID NO：8)
Figure PCTCN2021112771-appb-000018
19F3H2L2及19F3H2L3重链可变区的核酸序列：(SEQ ID NO：9)
Figure PCTCN2021112771-appb-000019
19F3H2L2及19F3H2L3重链可变区的氨基酸序列：(SEQ ID NO：10)
Figure PCTCN2021112771-appb-000020
19F3H2L2轻链可变区的核酸序列：(SEQ ID NO：11)
Figure PCTCN2021112771-appb-000021
19F3H2L2轻链可变区的氨基酸序列：(SEQ ID NO：12)
Figure PCTCN2021112771-appb-000022
19F3H2L3轻链可变区的核酸序列：(SEQ ID NO：13)
Figure PCTCN2021112771-appb-000023
19F3H2L3轻链可变区的氨基酸序列：(SEQ ID NO：14)
Figure PCTCN2021112771-appb-000024
19F3和19F3H2L3的CDR区
HCDR1：GYSFTGYT(SEQ ID NO：15)
HCDR2：INPYNAGT(SEQ ID NO：16)
HCDR3：ARSEYRYGGDYFDY(SEQ ID NO：17)
LCDR1：QSLLNSSNQKNY(SEQ ID NO：18)
LCDR2：FAS(SEQ ID NO：19)
LCDR3：QQHYDTPYT(SEQ ID NO：20)
CPI-006重链氨基酸序列SEQ ID NO：21
Figure PCTCN2021112771-appb-000025
Figure PCTCN2021112771-appb-000026
CPI-006轻链氨基酸序列SEQ ID NO：22
Figure PCTCN2021112771-appb-000027
19F3H2L3(hG1DM)重链全长氨基酸序列SEQ ID NO：23
Figure PCTCN2021112771-appb-000028
19F3H2L3(hG1DM)轻链全长氨基酸序列SEQ ID NO：24
Figure PCTCN2021112771-appb-000029
Figure PCTCN2021112771-appb-000030
注：下划线表示CDR序列

Claims (18)

  1. 抗CD73(例如人CD73)抗体或其抗原结合片段，用于治疗冠状病毒感染引起的疾病，其中，所述抗CD73抗体包含：
    SEQ ID NO：2所示重链可变区中包含的HCDR1，HCDR2和HCDR3，和SEQ ID NO：4所示的轻链可变区中包含的LCDR1，LCDR2和LCDR3，
    优选地，所述抗CD73抗体包含：
    HCDR1，其包含SEQ ID NO：15所示的氨基酸序列，与所述序列具有至少80％、81％、82％、83％、84％、85％、86％、87％、88％、89％、90％，优选至少91％、92％、93％、94％、95％、96％、97％、98％或99％序列同一性的序列，或与所述序列相比具有一个或多个(优选1个、2个或3个)保守氨基酸突变(优选置换，插入或缺失)的氨基酸序列，或由其组成，
    HCDR2，其包含SEQ ID NO：16所示的氨基酸序列，与所述序列具有至少80％、81％、82％、83％、84％、85％、86％、87％、88％、89％、90％，优选至少91％、92％、93％、94％、95％、96％、97％、98％或99％序列同一性的序列，或与所述序列相比具有一个或多个(优选1个、2个或3个)保守氨基酸突变(优选置换，插入或缺失)的氨基酸序列，或由其组成，
    HCDR3，其包含SEQ ID NO：17所示的氨基酸序列，与所述序列具有至少80％、81％、82％、83％、84％、85％、86％、87％、88％、89％、90％，优选至少91％、92％、93％、94％、95％、96％、97％、98％或99％序列同一性的序列，或与所述序列相比具有一个或多个(优选1个、2个或3个)保守氨基酸突变(优选置换，插入或缺失)的氨基酸序列，或由其组成，
    LCDR1，其包含SEQ ID NO：18所示的氨基酸序列，与所述序列具有至少80％、81％、82％、83％、84％、85％、86％、87％、88％、89％、90％，优选至少91％、92％、93％、94％、95％、96％、97％，98％或99％序列同一性的序列，或与所述序列相比具有一个或多个(优选1个、2个 或3个)保守氨基酸突变(优选置换，插入或缺失)的氨基酸序列，或由其组成，
    LCDR2，其包含SEQ ID NO：19所示的氨基酸序列，与所述序列具有至少80％、81％、82％、83％、84％、85％、86％、87％、88％、89％、90％，优选至少91％、92％、93％、94％、95％、96％、97％，98％或99％序列同一性的序列，或与所述序列相比具有一个或多个(优选1个、2个或3个)保守氨基酸突变(优选置换，插入或缺失)的氨基酸序列，或由其组成，和
    LCDR3，其包含SEQ ID NO：20所示的氨基酸序列，与所述序列具有至少80％、81％、82％、83％、84％、85％、86％、87％、88％、89％、90％，优选至少91％、92％、93％、94％、95％、96％、97％、98％或99％序列同一性的序列，或与所述序列相比具有一个或多个(优选1个、2个或3个)保守氨基酸突变(优选置换，插入或缺失)的氨基酸序列，或由其组成。
  2. 权利要求1所述的抗CD73抗体或其抗原结合片段，所述抗体的重链可变区包含下述序列，或由下述序列组成：
    SEQ ID NO：2、SEQ ID NO：6或SEQ ID NO：10，与SEQ ID NO：2、SEQ ID NO：6或SEQ ID NO：10具有至少80％、81％、82％、83％、84％、85％、86％、87％、88％、89％、90％，优选至少91％、92％、93％、94％、95％、96％、97％、98％或99％序列同一性的序列，或与SEQ ID NO：2、SEQ ID NO：6或SEQ ID NO：10所示的氨基酸序列相比具有一个或多个(优选1、2、3、4、5、6、7、8、9或10个)保守氨基酸突变(优选置换，插入或缺失)的氨基酸序列；并且
    所述抗体的轻链可变区包含下述序列，或由下述序列组成：
    SEQ ID NO：4、SEQ ID NO：8、SEQ ID NO：12或SEQ ID NO：14，与SEQ ID NO：4、SEQ ID NO：8、SEQ ID NO：12或SEQ ID NO：14具有至少80％、81％、82％、83％、84％、85％、86％、87％、88％、89％、90％，优选至少91％、92％、93％、94％、95％、96％、97％、98％或99％序列同一性的序列，或与SEQ ID NO：4、SEQ ID NO：8、SEQ ID NO：12或SEQ ID NO：14所示的氨基酸序列相比具有一个或多个(优选1、2、 3、4、5、6、7、8、9或10个)保守氨基酸突变(优选置换，插入或缺失)的氨基酸序列。
  3. 权利要求1或2所述的抗CD73抗体或其抗原结合片段，其中
    所述抗体的重链可变区的氨基酸序列如SEQ ID NO：2所示，并且所述抗体的轻链可变区的氨基酸序列如SEQ ID NO：4所示；
    所述抗体的重链可变区的氨基酸序列如SEQ ID NO：6所示，并且所述抗体的轻链可变区的氨基酸序列如SEQ ID NO：8所示；
    所述抗体的重链可变区的氨基酸序列如SEQ ID NO：10所示，并且所述抗体的轻链可变区的氨基酸序列如SEQ ID NO：12所示；或
    所述抗体的重链可变区的氨基酸序列如SEQ ID NO：10所示，并且所述抗体的轻链可变区的氨基酸序列如SEQ ID NO：14所示。
  4. 权利要求1或2所述的抗CD73抗体或其抗原结合片段，其中所述抗体的重链恒定区为Ig gamma-1链C区，ACCESSION：P01857；轻链恒定区为Ig kappa链C区，ACCESSION：P01834。
  5. 权利要求1或2所述的抗CD73抗体或其抗原结合片段，其中所述抗体为单克隆抗体(优选地，所述抗CD73抗体为保藏号为CCTCC NO：C2018137的杂交瘤分泌的单克隆抗体)、人源化抗体、嵌合抗体、多特异性抗体(例如双特异性抗体)，优选地，所述抗体的重链氨基酸序列如SEQ ID NO：23所示，轻链氨基酸序列如SEQ ID NO：24所示。
  6. 权利要求1或2所述的抗CD73抗体或其抗原结合片段，所述抗原结合片段选自Fab、Fab′、F(ab′) 2、Fd、Fv、dAb、Fab/c、互补决定区片段、单链抗体(例如，scFv)、人源化抗体、嵌合抗体或双特异性抗体。
  7. 偶联物，用于治疗冠状病毒感染引起的疾病，所述偶联物包含权利要求1-6任一项所述的抗CD73抗体或其抗原结合片段以及偶联部分，其中，所述偶联部分为纯化标签(如His标签)，可检测的标记或小分子药物；优选地，所述偶联部分为放射性同位素、荧光物质、化学发光物质、有色物质、聚乙二醇或酶；优选地，所述小分子药物为小分子细胞毒药物；更优选地，所述小分子药物为肿瘤化疗药物，更优选地，所述抗CD73抗体或其抗原结合片段通过连接子与小分子药物连接；例如， 所述连接子为腙键、二硫键或肽键；更优选地，所述抗CD73抗体或其抗原结合片段与小分子药物以一定的摩尔比连接；例如，所述摩尔比为1∶(2-4)。
  8. 融合蛋白或多特异性抗体(优选双特异性抗体)，用于治疗冠状病毒感染引起的疾病，其包含权利要求1-6任一项所述的抗CD73抗体或其抗原结合片段。
  9. 试剂盒，其包括权利要求1-6任一项所述的抗CD73抗体或其抗原结合片段、权利要求7所述的偶联物或权利要求8所述的融合蛋白或多特异性抗体；优选地，所述试剂盒还包括第二抗体或用作疫苗的抗原，所述第二抗体特异性识别所述抗CD73抗体或用于治疗病毒(优选冠状病毒科病毒感染)，所述用作疫苗的抗原选自源自病毒、细菌、真菌、立克次体、衣原体、支原体、寄生虫、朊病毒或肿瘤；任选地，所述第二抗体还包括可检测的标记，例如放射性同位素、荧光物质、化学发光物质、有色物质或酶；优选地，所述试剂盒用于检测CD73在样品中的存在或其水平。
  10. 药物组合物或单次药物剂量单元，用于治疗冠状病毒感染引起的疾病，其包含权利要求1-6任一项所述的抗CD73抗体或其抗原结合片段、权利要求7所述的偶联物或权利要求8所述的融合蛋白或多特异性抗体；可选地，所述药物组合物或单次药物剂量单元还包括药学上可接受的载体和/或赋形剂。优选地，所述药物组合物为适于通过皮下注射、皮内注射、静脉内注射、肌内注射或病灶内注射施用的形式。
  11. 权利要求1-6任一项所述的抗CD73抗体或其抗原结合片段、权利要求7所述的偶联物或权利要求8所述的融合蛋白或多特异性抗体在制备治疗和/或预防冠状病毒感染的药物或试剂盒中的用途，优选地，所述冠状病毒病毒选自新型冠状病毒SARS-CoV-2，HCoV-229E、HCoV-OC43、HCoV-NL63、HCoV-HKU1、SARS-CoV和/或MERS-CoV。
  12. 治疗和/或预防冠状病毒感染的方法，包括向受试者或患者施用有效量的权利要求1-6任一项所述的抗CD73抗体或其抗原结合片段、权利要求7所述的偶联物或权利要求8所述的融合蛋白或多特异性抗体，优选地，所述冠状病毒病毒选自新型冠状病毒SARS-CoV-2， HCoV-229E、HCoV-OC43、HCoV-NL63、HCoV-HKU1、SARS-CoV和/或MERS-CoV；更优选地，向所述受试者或患者同时或顺序施用抗病毒药物，优选地，所述抗病毒药物为RNA病毒抑制剂。
  13. 权利要求12所述的方法，更优选地，所述抗CD73抗体或其抗原结合片段、偶联物、融合蛋白或多特异性抗体的有效量为0.001mg-1000mg，更优选0.001mg-900mg、0.001mg-800mg、0.001mg-700mg、0.001mg-600mg、0.001mg-500mg、0.001mg-400mg、0.001mg-300mg、0.001mg-200mg、0.001mg-100mg，最优选为100mg、200mg、300mg、400mg、500mg、600mg、700mg、800mg、900mg或1000mg，或者，基于受试者或患者的体重，有效量为0.1-100mg/kg，优选1-90mg/kg、1-80mg/kg、1-70mg/kg、1-60mg/kg、1-50mg/kg、1-40mg/kg、1-30mg/kg、1-20mg/kg或1-10mg/kg；
  14. 权利要求12所述的方法，所述抗病毒药物的有效量为100-2400mg，优选100mg-2300mg、100mg-2200mg、100mg-2100mg、100mg-2000mg、100mg-1900mg、100mg-1800mg、100mg-1700mg、100mg-1600mg、100mg-1800mg、100mg-1800mg、100mg-1800mg、100mg-1800mg、100mg-1800mg，更优选为100mg，200mg，300mg，400mg，500mg，600mg，700mg，800mg，900mg，1000mg，或者，基于受试者或患者的体重，所述抗病毒药物的有效量为0.1-100mg/kg，优选1-90mg/kg、1-80mg/kg、1-70mg/kg、1-60mg/kg、1-50mg/kg、1-40mg/kg、1-30mg/kg、1-20mg/kg或1-10mg/kg。
  15. 权利要求1-6任一项所述的抗CD73抗体或其抗原结合片段、权利要求7所述的偶联物或权利要求8所述的融合蛋白或多特异性抗体，其作为助剂用于增强生物体对抗原的免疫反应。
  16. 权利要求1-6任一项所述的抗CD73抗体或其抗原结合片段、权利要求7所述的偶联物或权利要求8所述的融合蛋白或多特异性抗体，其中所述抗原源自病毒、细菌、真菌、立克次体、衣原体、支原体、寄生虫、朊病毒或肿瘤；
    优选地，所述病毒包括RNA病毒及DNA病毒；
    优选地，所述RNA病毒包括冠状病毒科病毒；
    优选地，所述冠状病毒科病毒包括2019新型冠状病毒(2019-nCoV 或SARS-CoV-2，引发新型冠状病毒肺炎COVID-19)，HCoV-229E、HCoV-OC43、HCoV-NL63、HCoV-HKU1、SARS-CoV(引发重症急性呼吸综合征)和MERS-CoV(引发中东呼吸综合征)。
  17. 提高疫苗效力或增强生物体对疫苗反应性的方法，包括在给予受试者疫苗同时、之前或之后，向所述受试者给予权利要求1-6任一项所述的抗CD73抗体或其抗原结合片段、权利要求7所述的偶联物或权利要求8所述的融合蛋白或多特异性抗体，优选所述疫苗中包含的抗原源自病毒、细菌、真菌、立克次体、衣原体、支原体、寄生虫、朊病毒或肿瘤；
    优选地，所述病毒包括RNA病毒及DNA病毒；
    优选地，所述RNA病毒包括冠状病毒科病毒；
    优选地，所述冠状病毒科病毒包括2019新型冠状病毒(2019-nCoV或SARS-CoV-2，引发新型冠状病毒肺炎COVID-19)，HCoV-229E、HCoV-OC43、HCoV-NL63、HCoV-HKU1、SARS-CoV(引发重症急性呼吸综合征)和MERS-CoV(引发中东呼吸综合征)。
  18. 权利要求17的方法，其中权利要求1-6任一项所述的抗CD73抗体或其抗原结合片段、权利要求7所述的偶联物或权利要求8所述的融合蛋白或多特异性抗体被给予(优选静脉给予)单次或多次。
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