WO2022206868A1 - 用于筛选功能性抗原结合蛋白的载体和方法 - Google Patents

用于筛选功能性抗原结合蛋白的载体和方法 Download PDF

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WO2022206868A1
WO2022206868A1 PCT/CN2022/084229 CN2022084229W WO2022206868A1 WO 2022206868 A1 WO2022206868 A1 WO 2022206868A1 CN 2022084229 W CN2022084229 W CN 2022084229W WO 2022206868 A1 WO2022206868 A1 WO 2022206868A1
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vector
fragment
polynucleotide
nucleic acid
seq
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PCT/CN2022/084229
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French (fr)
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周辰
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泷搌（上海）生物科技有限公司
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Priority to EP22779050.8A priority Critical patent/EP4317549A1/en
Priority to JP2023561051A priority patent/JP2024513871A/ja
Priority to BR112023019896A priority patent/BR112023019896A2/pt
Priority to KR1020237037214A priority patent/KR20230164128A/ko
Priority to CN202280025128.6A priority patent/CN117136258A/zh
Publication of WO2022206868A1 publication Critical patent/WO2022206868A1/zh

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    • C—CHEMISTRY; METALLURGY
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    • C12N15/00—Mutation or genetic engineering; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification; Use of hosts therefor
    • C12N15/09—Recombinant DNA-technology
    • C12N15/10—Processes for the isolation, preparation or purification of DNA or RNA
    • C12N15/1034—Isolating an individual clone by screening libraries
    • C12N15/1037—Screening libraries presented on the surface of microorganisms, e.g. phage display, E. coli display
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K16/00—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K16/00—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies
    • C07K16/005—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies constructed by phage libraries
    • 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
    • C07K16/2803—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants against the immunoglobulin superfamily
    • 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
    • C07K16/2803—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants against the immunoglobulin superfamily
    • C07K16/2818—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants against the immunoglobulin superfamily against CD28 or CD152
    • 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
    • C07K16/2878—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants against the NGF-receptor/TNF-receptor superfamily, e.g. CD27, CD30, CD40, CD95
    • 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
    • C07K16/32—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against translation products of oncogenes
    • C—CHEMISTRY; METALLURGY
    • C40—COMBINATORIAL TECHNOLOGY
    • C40B—COMBINATORIAL CHEMISTRY; LIBRARIES, e.g. CHEMICAL LIBRARIES
    • C40B40/00—Libraries per se, e.g. arrays, mixtures
    • C40B40/02—Libraries contained in or displayed by microorganisms, e.g. bacteria or animal cells; Libraries contained in or displayed by vectors, e.g. plasmids; Libraries containing only microorganisms or vectors
    • C—CHEMISTRY; METALLURGY
    • C40—COMBINATORIAL TECHNOLOGY
    • C40B—COMBINATORIAL CHEMISTRY; LIBRARIES, e.g. CHEMICAL LIBRARIES
    • C40B40/00—Libraries per se, e.g. arrays, mixtures
    • C40B40/04—Libraries containing only organic compounds
    • C40B40/06—Libraries containing nucleotides or polynucleotides, or derivatives thereof
    • C40B40/08—Libraries containing RNA or DNA which encodes proteins, e.g. gene libraries
    • C—CHEMISTRY; METALLURGY
    • C40—COMBINATORIAL TECHNOLOGY
    • C40B—COMBINATORIAL CHEMISTRY; LIBRARIES, e.g. CHEMICAL LIBRARIES
    • C40B50/00—Methods of creating libraries, e.g. combinatorial synthesis
    • C40B50/06—Biochemical methods, e.g. using enzymes or whole viable microorganisms
    • 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
    • A61K2039/507—Comprising a combination of two or more separate antibodies
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/20—Immunoglobulins specific features characterized by taxonomic origin
    • C07K2317/21—Immunoglobulins specific features characterized by taxonomic origin from primates, e.g. man
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/50—Immunoglobulins specific features characterized by immunoglobulin fragments
    • C07K2317/55—Fab or Fab'
    • 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
    • C07K2317/73—Inducing cell death, e.g. apoptosis, necrosis or inhibition of cell proliferation
    • 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 application relates to the field of biomedicine, in particular to a vector for constructing and expressing an antigen-binding protein, and a screening method for a functional antigen-binding protein.
  • the widely used methods for obtaining functional antibodies or antigen-binding fragments thereof with desired properties mainly include hybridoma technology and antibody library technology.
  • the hybridoma technology has the problems of a small number of candidate clones and easy loss of positive clones, and the selection of positive clones, especially for complex functional screening, requires a lot of time and workload.
  • Antibody library technology refers to the use of genetic engineering to clone the variable region genes of antibody heavy and light chains into plasmids or phages and express them, and then use different antigens to screen clones carrying specific antibody genes, which mainly include phage display. technology and yeast surface display technology.
  • Antibody library technology greatly improves the capacity, but the target antigen generally has multiple (eg, several, dozens, or even hundreds) epitopes, but the epitope with the desired biological function may only have one or several.
  • the target antigen generally has multiple (eg, several, dozens, or even hundreds) epitopes, but the epitope with the desired biological function may only have one or several.
  • antigenic determinant has the desired biological function.
  • a large number of antigen-specific antibodies or their antigen-binding fragments are usually obtained first, and then analyzed and identified one by one to find out the antibodies or their antigen-binding fragments that bind to specific antigenic determinants and have desired biological functions, which still requires a long period of time. time and large workload, and the screening effect is not good. Therefore, new technologies for the discovery of antibodies or their antigen-binding fragments are needed to improve the quality, quantity and diversity of lead molecules, speed up drug development, and improve the success rate of development.
  • the application provides a method of selecting a functional antigen binding protein comprising, a) providing a first polynucleotide comprising an R1-nucleic acid in a 5' to 3' orientation Fragment I-R2, said nucleic acid fragment I capable of encoding antigen-binding fragment I; b) providing a second polynucleotide comprising R3-reference nucleic acid fragment II in 5' to 3' orientation -R4, the reference nucleic acid fragment II is capable of encoding a reference antigen-binding fragment II, and the reference antigen-binding fragment II is capable of forming a reference antigen-binding protein with the reference antigen-binding fragment I encoded by the reference nucleic acid fragment I; c) providing a first carrier polynucleotide comprising the R2-carrier fragment I-R3 in the 5' to 3' direction; d) providing a second carrier polynucleotide, the second carrier polynucleotide nu
  • the method comprises cleaving the first polynucleotide with a restriction endonuclease that specifically recognizes the R1 and R2 to obtain the cleaved first polynucleotide.
  • the method comprises cleaving the second polynucleotide with a restriction endonuclease that specifically recognizes the R3 and R4 to obtain the cleaved second polynucleotide.
  • the method comprises cleaving the first carrier polynucleotide with a restriction endonuclease that specifically recognizes the R2 and R3 to obtain the cleaved first carrier polynucleotide.
  • the method comprises cleaving the second carrier polynucleotide with a restriction endonuclease that specifically recognizes the R4 and R1 to obtain the cleaved second carrier polynucleotide.
  • the end resulting from the specific cleavage of the R1 by a restriction endonuclease that specifically recognizes it is not associated with any of the R2, R3 and R4 by the corresponding restriction endonuclease
  • the resulting ends after specific cleavage by the enzyme recognize or join each other.
  • the end resulting from the specific cleavage of the R2 by a restriction endonuclease that specifically recognizes it is not cut with the corresponding restriction endonuclease with any of the R1, R3 and R4
  • the resulting ends after specific cleavage by the enzyme recognize or join each other.
  • the terminus generated after the specific cleavage of the R3 by a restriction endonuclease that specifically recognizes it does not undergo a corresponding restriction endonuclease with any of the R1, R2 and R4
  • the resulting ends after specific cleavage by the enzyme recognize or join each other.
  • the terminus resulting from the specific cleavage of the R4 by a restriction endonuclease that specifically recognizes it is not cut with a corresponding restriction endonuclease with any of the R1, R2 and R3
  • the resulting ends after specific cleavage by the enzyme recognize or join each other.
  • the restriction endonuclease is selected from the group consisting of SfiI and BsmBI.
  • the method comprises introducing the first vector to be screened into a cell to express the first vector to be screened.
  • the method comprises introducing the first vector to be screened into bacteria, preparing a phage library comprising one or more of the first vector to be screened, and obtaining the functional antigen from the phage library binding protein.
  • the vector fragment I comprises a linker and the vector fragment II is derived from a display vector.
  • the nucleic acid fragment I encodes an antibody light chain or a fragment thereof
  • the vector fragment I comprises the linker
  • the reference nucleic acid fragment II encodes an antibody heavy chain or a fragment thereof
  • the vector Fragment II is derived from the display vector.
  • the R1 comprises the nucleotide sequence set forth in SEQ ID NO:1.
  • the R2 comprises the nucleotide sequence set forth in SEQ ID NO:2.
  • the R3 comprises the nucleotide sequence set forth in SEQ ID NO:3.
  • the R4 comprises the nucleotide sequence set forth in SEQ ID NO:4.
  • the vector fragment II comprises a linker, and the vector fragment I is derived from a display vector.
  • the nucleic acid fragment I encodes an antibody heavy chain or fragment thereof
  • the vector fragment I is derived from the display vector
  • the reference nucleic acid fragment II encodes an antibody light chain or fragment thereof
  • the Vector fragment II contains the linker.
  • the R1 comprises the nucleotide sequence set forth in SEQ ID NO:3.
  • the R2 comprises the nucleotide sequence set forth in SEQ ID NO:4.
  • the R3 comprises the nucleotide sequence set forth in SEQ ID NO:1.
  • the R4 comprises the nucleotide sequence set forth in SEQ ID NO:2.
  • the display vector is derived from the pComb3x vector.
  • the linker comprises a nucleic acid sequence encoding the signal peptide pelB or a fragment thereof.
  • the linker is about 50 to about 200 bases in length.
  • the method comprises introducing the first vector to be screened into bacteria, obtaining the DNA of the first vector to be screened from the bacteria, and introducing the DNA of the first vector to be screened into cells;
  • the functional antigen-specific binding polypeptide is obtained from the cell.
  • the cells are mammalian cells.
  • the vector fragment I and/or the vector fragment II are derived from mammalian cell expression vectors.
  • the mammalian cell expression vector is derived from pDGB4.
  • the nucleic acid fragment I encodes an antibody light chain or fragment thereof
  • the reference nucleic acid fragment II encodes an antibody heavy chain or fragment thereof.
  • the R1 comprises the nucleotide sequence set forth in SEQ ID NO:7.
  • the R2 comprises the nucleotide sequence set forth in SEQ ID NO:8.
  • the R3 comprises the nucleotide sequence set forth in SEQ ID NO:5.
  • the R4 comprises the nucleotide sequence set forth in SEQ ID NO:6.
  • the nucleic acid fragment I encodes an antibody heavy chain or fragment thereof
  • the reference nucleic acid fragment II encodes an antibody light chain or fragment thereof.
  • the R1 comprises the nucleotide sequence set forth in SEQ ID NO:5.
  • the R2 comprises the nucleotide sequence set forth in SEQ ID NO:6.
  • the R3 comprises the nucleotide sequence set forth in SEQ ID NO:7.
  • the R4 comprises the nucleotide sequence set forth in SEQ ID NO:8.
  • the method comprises: a) providing a third polynucleotide comprising R5-nucleic acid fragment I'-R6 in a 5' to 3' orientation; b) providing a fourth polynucleotide comprising R7-nucleic acid fragment II'-R8 in the 5' to 3' direction, the nucleic acid fragment II' capable of encoding an antigen binding protein II', and the antigen
  • the binding fragment II' can form an antigen-binding protein with the reference antigen-binding fragment I with the following properties: can bind to the target that the reference antigen-binding protein can bind to, and the binding ability to the target is that the reference antigen binds more than 30% of the binding ability of the protein to the target; c) providing a third carrier polynucleotide comprising R6-carrier fragment III-R7 in the 5' to 3' direction; d) providing the third carrier polynucleotide Four vector polynucleotides comprising R8
  • the method comprises cleaving the third polynucleotide with a restriction endonuclease that specifically recognizes the R5 and R6 to obtain the cleaved third polynucleotide.
  • the method comprises cleaving the fourth polynucleotide with a restriction endonuclease that specifically recognizes the R7 and R8 to obtain the cleaved fourth polynucleotide.
  • the method comprises cleaving the third carrier polynucleotide with a restriction endonuclease that specifically recognizes the R6 and R7 to obtain the cleaved third carrier polynucleotide.
  • the method comprises cleaving the fourth carrier polynucleotide with a restriction endonuclease that specifically recognizes the R8 and R5 to obtain the cleaved fourth carrier polynucleotide.
  • the end generated after the R5 is specifically cleaved by a restriction endonuclease that specifically recognizes it is not cut with the corresponding restriction endonuclease with any of the R6, R7 and R8
  • the resulting ends after specific cleavage by the enzyme recognize or join each other.
  • the end generated after the R6 is specifically cleaved by a restriction endonuclease that specifically recognizes it is not cut with the corresponding restriction endonuclease with any of the R5, R7 and R8 The resulting ends after specific cleavage by the enzyme recognize or join each other.
  • the end generated after the R7 is specifically cleaved by a restriction endonuclease that specifically recognizes it is not cut with a corresponding restriction endonuclease with any of the R5, R6 and R8
  • the resulting ends after specific cleavage by the enzyme recognize or join each other.
  • the end generated after the R8 is specifically cleaved by a restriction endonuclease that specifically recognizes it is not cut with the corresponding restriction endonuclease with any of the R5, R6 and R7
  • the resulting ends after specific cleavage by the enzyme recognize or join each other.
  • the restriction endonuclease is selected from the group consisting of SfiI and BsmBI.
  • the method comprises introducing the double-displacement vector to be screened into a cell to express the double-displacement vector to be selected for.
  • the method comprises introducing the double-substitution vectors to be screened into bacteria, preparing a phage library comprising one or more of the double-substitution vectors to be screened, and obtaining the functional antigen from the phage library binding protein.
  • the vector fragment III comprises a linker
  • the vector fragment IV is derived from a display vector.
  • the nucleic acid fragment I' encodes an antibody light chain or a fragment thereof
  • the vector fragment III comprises the linker
  • the nucleic acid fragment II' encodes an antibody heavy chain or a fragment thereof
  • the vector Fragment IV is derived from the display vector.
  • the R5 comprises the nucleotide sequence set forth in SEQ ID NO:1.
  • the R6 comprises the nucleotide sequence set forth in SEQ ID NO:2.
  • the R7 comprises the nucleotide sequence set forth in SEQ ID NO:3.
  • the R8 comprises the nucleotide sequence set forth in SEQ ID NO:4.
  • the vector fragment IV comprises a linker, and the vector fragment III is derived from a display vector.
  • the nucleic acid fragment I' encodes an antibody heavy chain or a fragment thereof
  • the vector fragment III is derived from the display vector
  • the nucleic acid fragment II' encodes an antibody light chain or a fragment thereof
  • the Vector fragment IV contains the linker.
  • the R5 comprises the nucleotide sequence set forth in SEQ ID NO:3.
  • the R6 comprises the nucleotide sequence set forth in SEQ ID NO:4.
  • the R7 comprises the nucleotide sequence set forth in SEQ ID NO:1.
  • the R8 comprises the nucleotide sequence set forth in SEQ ID NO:2.
  • the display vector is derived from the pComb3x vector.
  • the linker comprises a nucleic acid sequence encoding the signal peptide pelB or a fragment thereof.
  • the linker is about 50 to about 200 bases in length.
  • the method comprises introducing the dual-display vector to be screened into bacteria, obtaining the DNA of the dual-display vector to be screened from the bacteria, and introducing the DNA of the dual-display vector to be screened into cells;
  • the functional antigen-specific binding polypeptide is obtained from the cell.
  • the cells are mammalian cells.
  • the vector fragment III and/or the vector fragment IV are derived from mammalian expression vectors.
  • the mammalian expression vector is derived from pDGB4.
  • the nucleic acid fragment I' encodes an antibody light chain or fragment thereof
  • the nucleic acid fragment II' encodes an antibody heavy chain or fragment thereof.
  • the R5 comprises the nucleotide sequence set forth in SEQ ID NO:7.
  • the R6 comprises the nucleotide sequence set forth in SEQ ID NO:8.
  • the R7 comprises the nucleotide sequence set forth in SEQ ID NO:5.
  • the R8 comprises the nucleotide sequence set forth in SEQ ID NO:6.
  • the nucleic acid fragment I' encodes an antibody heavy chain or fragment thereof
  • the nucleic acid fragment II' encodes an antibody light chain or fragment thereof.
  • the R5 comprises the nucleotide sequence set forth in SEQ ID NO:5.
  • the R6 comprises the nucleotide sequence set forth in SEQ ID NO:6.
  • the R7 comprises the nucleotide sequence set forth in SEQ ID NO:7.
  • the R8 comprises the nucleotide sequence set forth in SEQ ID NO:8.
  • the method comprises: a) providing a fifth polynucleotide comprising R9-reference nucleic acid fragment I-R10 in a 5' to 3' orientation; b) providing a sixth polynucleotide comprising R11-nucleic acid fragment II-R12 in the 5' to 3' direction; c) providing a fifth carrier polynucleotide, the fifth carrier polynucleotide comprising the R10-vector fragment V-R11 in the 5' to 3' direction; d) providing a sixth carrier polynucleotide comprising the R12-vector fragment VI-R9 in the 5' to 3' direction; e) cleaving the fifth polynucleotide, the sixth polynucleotide, the fifth carrier polynucleotide and the sixth carrier polynucleotide with a restriction endonuclease to obtain the cleaved the fifth polynucleotide, the sixth polynucle
  • the method comprises cleaving the fifth polynucleotide with a restriction endonuclease that specifically recognizes the R9 and R10 to obtain the cleaved fifth polynucleotide.
  • the method comprises cleaving the sixth polynucleotide with a restriction endonuclease that specifically recognizes the R11 and R12 to obtain the cleaved sixth polynucleotide.
  • the method comprises cleaving the fifth carrier polynucleotide with a restriction endonuclease that specifically recognizes the R10 and R11 to obtain the cleaved fifth carrier polynucleotide.
  • the method comprises cleaving the sixth carrier polynucleotide with a restriction endonuclease that specifically recognizes the R12 and R9 to obtain the cleaved sixth carrier polynucleotide.
  • the end generated after the R9 is specifically cleaved by a restriction endonuclease that specifically recognizes it is not cut with the corresponding restriction endonuclease with any of the R10, R11 and R12
  • the resulting ends after specific cleavage by the enzyme recognize or join each other.
  • the end resulting from the specific cleavage of the R10 by a restriction endonuclease that specifically recognizes it does not undergo a corresponding restriction endonuclease with any of the R11, R12 and R9
  • the resulting ends after specific cleavage by the enzyme recognize or join each other.
  • the end resulting from the specific cleavage of the R11 by a restriction endonuclease that specifically recognizes it does not undergo a corresponding restriction endonuclease with any of the R9, R10 and R12
  • the resulting ends after specific cleavage by the enzyme recognize or join each other.
  • the end resulting from the specific cleavage of the R12 by a restriction endonuclease that specifically recognizes it does not undergo a corresponding restriction endonuclease with any of the R9, R10 and R11
  • the resulting ends after specific cleavage by the enzyme recognize or join each other.
  • the restriction endonuclease is selected from the group consisting of SfiI and BsmBI.
  • the method comprises introducing the second vector to be screened into a cell to express the second vector to be screened.
  • the method comprises introducing the second vector to be screened into bacteria, preparing a phage library comprising one or more of the second vector to be screened, and obtaining the functional antigen from the phage library binding protein.
  • the vector fragment V comprises a linker
  • the vector fragment VI is derived from a display vector.
  • the reference nucleic acid fragment I encodes an antibody light chain or fragment thereof
  • the vector fragment V comprises the linker
  • the nucleic acid fragment II encodes an antibody heavy chain or fragment thereof
  • the vector Fragment VI is derived from the display vector.
  • the R9 comprises the nucleotide sequence set forth in SEQ ID NO:1.
  • the R10 comprises the nucleotide sequence set forth in SEQ ID NO:2.
  • the R11 comprises the nucleotide sequence set forth in SEQ ID NO:3.
  • the R12 comprises the nucleotide sequence set forth in SEQ ID NO:4.
  • the vector fragment VI comprises a linker, and the vector fragment V is derived from a display vector.
  • the reference nucleic acid fragment I encodes an antibody heavy chain or fragment thereof
  • the vector fragment V is derived from the display vector
  • the nucleic acid fragment II encodes an antibody light chain or fragment thereof
  • the Vector fragment VI contains the linker.
  • the R9 comprises the nucleotide sequence set forth in SEQ ID NO:3.
  • the R10 comprises the nucleotide sequence set forth in SEQ ID NO:4.
  • the R11 comprises the nucleotide sequence set forth in SEQ ID NO:1.
  • the R12 comprises the nucleotide sequence set forth in SEQ ID NO:2.
  • the display vector is derived from the pComb3x vector.
  • the linker comprises a nucleic acid sequence encoding the signal peptide pelB or a fragment thereof.
  • the linker is about 50 to about 200 bases in length.
  • the method comprises introducing the second vector to be screened into bacteria, obtaining the DNA of the second vector to be screened from the bacteria, and introducing the DNA of the second vector to be screened into cells;
  • the functional antigen-specific binding polypeptide is obtained from the cell.
  • the cells are mammalian cells.
  • the vector fragment V and/or the vector fragment VI are derived from mammalian expression vectors.
  • the mammalian expression vector is derived from pDGB4.
  • the reference nucleic acid fragment I encodes an antibody light chain or fragment thereof
  • the reference fragment II encodes an antibody heavy chain or fragment thereof.
  • the R9 comprises the nucleotide sequence set forth in SEQ ID NO:7.
  • the R10 comprises the nucleotide sequence set forth in SEQ ID NO:8.
  • the R11 comprises the nucleotide sequence set forth in SEQ ID NO:5.
  • the R12 comprises the nucleotide sequence set forth in SEQ ID NO:6.
  • the reference nucleic acid fragment I encodes an antibody heavy chain or fragment thereof
  • the nucleic acid fragment II encodes an antibody light chain or fragment thereof.
  • the R9 comprises the nucleotide sequence set forth in SEQ ID NO:5.
  • the R10 comprises the nucleotide sequence set forth in SEQ ID NO:6.
  • the R11 comprises the nucleotide sequence set forth in SEQ ID NO:7.
  • the R12 comprises the nucleotide sequence set forth in SEQ ID NO:8.
  • the antigen binding protein comprises an antibody or antibody fragment.
  • the antibody fragment comprises scFv, Fab, Fab', (Fab) 2 and/or (Fab') 2 .
  • the directed ligation comprises the use of a ligase.
  • the ligase is a DNA ligase.
  • the present application provides a method for preparing an antigen-binding protein, comprising: under the condition that the first replacement vector, the second replacement vector and/or the double replacement vector are expressed, the The first replacement vector, the second replacement vector and/or the double replacement vector are expressed.
  • the present application provides a first displacement vector prepared according to the method.
  • the present application provides a second displacement vector prepared according to the method.
  • the present application provides a double displacement vector prepared according to the method.
  • the present application provides a functional antigen-binding protein prepared according to the method.
  • the present application provides a method of selecting a functional antigen-binding protein, the method comprising utilizing a reference antigen-binding fragment of a reference antigen-binding protein of known sequence and/or function (eg, reference antigen-binding fragment I and/or reference antigen-binding fragment). or with reference to antigen-binding fragment II) construct a vector (for example, the double-displacement vector to be screened, the first vector to be screened and/or the second vector to be screened), the vector is expressed, and then The functional antigen-binding protein is obtained by the binding activity of the expression product of the vector to the target recognized by the reference antigen-binding protein.
  • a reference antigen-binding fragment of a reference antigen-binding protein of known sequence and/or function eg, reference antigen-binding fragment I and/or reference antigen-binding fragment.
  • a vector for example, the double-displacement vector to be screened, the first vector to be screened and/or the second vector to be screened
  • the present application also provides a method for constructing the vector, and a functional antigen-binding protein obtained from the vector.
  • novel functional antigen bindings with desired properties are obtained by screening light and heavy chains or fragments thereof of reference antigen-binding proteins with known sequences and/or functions in the prior art, phage display technology or cell surface display technology in combination with antibodies
  • the functional antigen-binding protein obtained by screening and the reference antigen-binding protein have a high possibility of binding the same or similar epitopes of the same target, and have a high possibility of biological activity, high screening efficiency, and short screening time.
  • Fig. 1 shows the exemplary structure of the first vector to be screened described in this application
  • Figure 2 shows the exemplary structure of the double-replacement vector to be screened as described in the present application
  • Figure 3 shows an exemplary structure of the second vector to be screened in the present application.
  • Figure 4 shows the analysis results of the antibody agonistic activity of the antibody obtained by the method described in the present application.
  • FIG. 5 shows the analysis results of the antibody endocytosis activity of the antibody obtained by the method described in the present application.
  • Figure 6 shows the anti-tumor effect obtained by the method described in the present application when the antibody is administered alone.
  • Figure 7 shows the anti-tumor effect of the combined administration of antibodies obtained by the method described in the present application.
  • the term "reference antigen binding protein” generally refers to an antigen binding protein having at least one desired biological function. For example, it can specifically bind to a target with high affinity, can block the binding of a protein to a specific ligand, and/or can stimulate immune cells to secrete cytokines, etc.
  • the reference antigen binding protein can be an antigen binding protein (eg, an antibody) of known amino acid sequence and/or function from the prior art. In certain embodiments, the reference antigen binding protein is from a commercial antibody product and/or an antibody in a clinical trial.
  • reference antigen-binding protein and “reference antigen-binding fragment I” and/or “reference antigen-binding fragment II"
  • the PD-1 antibody Nivolumab, Pembrolizumab or Cemiplimab
  • the PD-1 antibody Atezolizumab, Avelumab or Durvalumab can be selected as the reference antigen-binding protein.
  • reference nucleic acid fragment I generally refers to a nucleic acid fragment capable of encoding a reference antigen-binding fragment I.
  • reference nucleic acid fragment II generally refers to a nucleic acid fragment capable of encoding a reference antigen-binding fragment II.
  • reference antigen-binding fragment I generally refers to a polypeptide fragment capable of forming a reference antigen-binding protein.
  • the "reference antigen-binding fragment I” can be an antibody heavy chain or a heavy chain variable region, or a heavy chain fragment, or an antibody light chain or a light chain variable region, or a light chain fragment.
  • reference antigen binding fragment II generally refers to a polypeptide fragment capable of forming a reference antigen binding protein.
  • the "reference antigen-binding fragment II” can be an antibody heavy chain or a heavy chain variable region, or a heavy chain fragment, or an antibody light chain or a light chain variable region, or a light chain fragment.
  • the "reference antigen-binding fragment I” can form an antigen-binding protein (eg, a reference antigen-binding protein) with the "reference antigen-binding fragment II".
  • antigen-binding protein generally refers to a protein comprising an antigen-binding moiety, and optionally a scaffold or backbone moiety that allows the antigen-binding moiety to adopt a conformation that facilitates the binding of the antigen-binding protein to the antigen.
  • Antigen binding proteins may typically comprise antibody light chain variable regions (VL), antibody heavy chain variable regions (VH), or both, and functional fragments thereof. The variable regions of the heavy and light chains contain binding domains that interact with the antigen.
  • antigen-binding proteins include, but are not limited to, antibodies, antigen-binding fragments, immunoconjugates, multispecific antibodies (eg, bispecific antibodies), antibody fragments, antibody derivatives, antibody analogs, or fusion proteins, etc., so long as they show The desired antigen-binding activity can be obtained.
  • antibody generally refers to an immunoglobulin reactive against a specified protein or peptide or fragment thereof.
  • Antibodies can be antibodies from any class, including but not limited to IgG, IgA, IgM, IgD, and IgE, and antibodies from any subclass (eg, IgGl, IgG2, IgG3, and IgG4).
  • the antibody may have a heavy chain constant region selected from, eg, IgGl, IgG2, IgG3, or IgG4.
  • the antibody may also have a light chain selected from, for example, kappa ( ⁇ ) or lambda ( ⁇ ).
  • the antibodies of the present application can be derived from any species.
  • the term “antigen binding protein” may refer to a portion of an antibody molecule comprising amino acid residues that interact with an antigen and confer specificity and affinity for the antibody to the antigen.
  • the term “antigen binding protein” may include antibodies or antibody fragments, especially those antibody portions comprising antibody light chains or fragments thereof (eg, VL) and antibody heavy chains or fragments thereof (eg, VH).
  • the antibody light chain or fragment thereof (eg, VL) and the antibody heavy chain or fragment thereof (eg, VH) can be linked at the N-terminus or C-terminus by a linker (eg, a peptide linker) to form a polypeptide chain.
  • the antibody light chain or fragment thereof eg, VL
  • the antibody heavy chain or fragment thereof eg, VH
  • interchain chemical bonds eg, disulfide bonds
  • antigen binding proteins may include, but are not limited to, Fab, Fab', F(ab) 2 , Fv fragments, F(ab') 2 , scFv, di-scFv and/or dAb.
  • the antigen binding protein can be a scFv or a Fab.
  • Fab generally refers to the generation of two identical antigen-binding fragments after papain digestion of an antibody with intact structure (eg, removal of the Fc region and hinge region).
  • a Fab may consist of the complete light chain, the variable region of the heavy chain (VH) and the first constant domain (CH1) of the heavy chain.
  • VH variable region of the heavy chain
  • CH1 first constant domain
  • scFv generally refers to a monovalent molecule formed by covalently linking and pairing one heavy chain variable domain and one light chain variable domain of an antibody via a flexible peptide linker.
  • the term "functional antigen-binding protein” generally refers to an antigen-binding protein with a desired function selected according to the method of the present application. For example, it can specifically bind to a target with high affinity, can block the binding of a protein to a specific ligand, and/or can stimulate immune cells to secrete cytokines, etc.
  • the functional antigen-binding protein has the following properties: it can bind to the target that the reference binding protein of the present application can bind to, and the binding capacity to the target is 30% of the binding capacity of the reference antigen-binding protein to the target.
  • a functional antigen-binding protein may comprise reference antigen-binding fragment I and antigen-binding fragment II'.
  • a functional antigen-binding protein may comprise reference antigen-binding fragment II and antigen-binding fragment I'.
  • a functional antigen-binding protein may comprise antigen-binding fragment I' and antigen-binding fragment II'.
  • nucleic acid fragment I generally refers to a nucleic acid molecule capable of expressing antigen-binding fragment I.
  • nucleic acid fragment I′ the nucleic acid fragment I expressed by it can form an antigen-binding protein with the reference antigen-binding fragment I expressed by the reference nucleic acid fragment II
  • the antigen-binding protein has one or more of the following properties: it can bind to the target specifically bound by the reference antigen-binding protein, and the binding ability to the target is the ability of the reference antigen-binding protein to bind to the target.
  • nucleic acid fragment I is a nucleic acid fragment I'.
  • antigen-binding fragment I expressed by nucleic acid fragment I is capable of forming an antigen-binding protein with the reference antigen-binding fragment II expressed by reference nucleic acid fragment II.
  • nucleic acid fragment I' generally refers to a nucleic acid molecule capable of expressing the antigen-binding fragment I'.
  • the antigen-binding fragment I' expressed by the nucleic acid fragment I' can form a functional antigen-binding protein with the reference antigen-binding fragment I expressed by the reference nucleic acid fragment II, and the antigen-binding protein has one or more of the following properties: Able to bind to the target specifically bound by the reference antigen-binding protein, and the binding capacity to the target is more than 30% of the binding capacity of the reference antigen-binding protein to the target (for example, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 99% or more).
  • nucleic acid fragment II generally refers to a nucleic acid molecule capable of expressing antigen-binding fragment II.
  • nucleic acid fragment II having the following properties is selected as the nucleic acid fragment II': the antigen-binding fragment II expressed by it is capable of forming an antigen-binding protein with the reference antigen-binding fragment I expressed by the reference nucleic acid fragment I, and the The antigen-binding protein has one or more of the following properties: capable of binding to the target specifically bound by the reference antigen-binding protein, and the binding ability to the target is that the reference antigen-binding protein binds to the target More than 30% of ability (e.g., 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 99% or more ).
  • nucleic acid fragment II is a nucleic acid fragment II'. Not every antigen-binding fragment II expressed by nucleic acid fragment II is capable of forming an antigen-binding protein with the reference antigen-binding fragment I expressed by reference nucleic acid fragment I.
  • nucleic acid fragment II' generally refers to a nucleic acid molecule capable of expressing antigen-binding fragment II'.
  • the antigen-binding protein II' expressed by the nucleic acid fragment II' can form a functional antigen-binding protein with the reference antigen-binding fragment I expressed by the reference nucleic acid fragment I, and the antigen-binding protein has one or more of the following properties: Able to bind to the target specifically bound by the reference antigen-binding protein, and the binding capacity to the target is more than 30% of the binding capacity of the reference antigen-binding protein to the target (for example, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 99% or more).
  • antigen-binding fragment I generally refers to the expression product of nucleic acid fragment I, which is encoded by nucleic acid fragment I.
  • antigen-binding fragment I′ capable of forming an antigen-binding protein with reference antigen-binding fragment II
  • the antigen-binding protein has one or more The following properties: capable of binding to the target specifically bound by the reference antigen-binding protein, and the binding capacity to the target is more than 30% of the binding capacity of the reference antigen-binding protein to the target (for example, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 99% or more).
  • antigen-binding fragment I can be an antibody heavy chain or a heavy chain variable region, or a heavy chain fragment, or an antibody light chain or a light chain variable region, or a light chain fragment.
  • antigen-binding fragment I' generally refers to the expression product of the nucleic acid fragment I', which is encoded by the nucleic acid fragment I'.
  • Antigen-binding fragment I' is a functional antigen-binding protein in antigen-binding fragment I that can be combined with reference antigen-binding fragment II, and the antigen-binding protein has one or more of the following properties: capable of binding to the reference antigen-binding
  • the target that the protein specifically binds to, and the binding capacity to the target is more than 30% of the binding capacity of the reference antigen-binding protein to the target (for example, 35%, 40%, 45%, 50%, 55% , 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or more than 99%).
  • antigen-binding fragment II generally refers to the expression product from nucleic acid fragment II, which is encoded by nucleic acid fragment II.
  • antigen-binding fragment II having the following properties can be selected as antigen-binding fragment II': capable of forming an antigen-binding protein with reference antigen-binding fragment I, and the antigen-binding protein has one or more The following properties: capable of binding to the target specifically bound by the reference antigen-binding protein, and the binding capacity to the target is more than 30% of the binding capacity of the reference antigen-binding protein to the target (for example, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 99% or more).
  • antigen-binding fragment II can be an antibody heavy chain or a heavy chain variable region, or a heavy chain fragment, or an antibody light chain or a light chain variable region, or a light chain fragment.
  • antigen-binding fragment II' generally refers to the expression product of nucleic acid fragment II', which is encoded by nucleic acid fragment II'.
  • Antigen-binding fragment II' is a functional antigen-binding protein in antigen-binding fragment II that can be combined with reference antigen-binding fragment I, and the antigen-binding protein has one or more of the following properties: capable of binding to the reference antigen-binding
  • the target that the protein specifically binds to, and the binding capacity to the target is more than 30% of the binding capacity of the reference antigen-binding protein to the target (for example, 35%, 40%, 45%, 50%, 55% , 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or more than 99%).
  • first polynucleotide generally refers to a polynucleotide comprising nucleic acid fragment I.
  • the first polynucleotide may also have a recognition site for an endonuclease (eg, a restriction endonuclease) at the 5' end and/or the 3' end.
  • the first polynucleotide may comprise the structure R1-nucleic acid fragment I-R2 in the 5' to 3' direction, wherein the R1, R2 may be recognition sites for restriction endonucleases.
  • the enzyme-digested first polynucleotide may comprise the nucleic acid fragment I.
  • first vector polynucleotide generally refers to a polynucleotide comprising vector fragment I.
  • the first vector polynucleotide may also have a recognition site for an endonuclease (eg, a restriction endonuclease) at the 5' end and/or the 3' end.
  • the first vector polynucleotide may comprise the structure R2-vector fragment I-R3 in the 5' to 3' direction, wherein the R2, R3 may be recognition sites for restriction endonucleases.
  • the enzyme-digested first vector polynucleotide may comprise the vector fragment I.
  • the term "second polynucleotide” generally refers to the polynucleotide comprising the reference nucleic acid fragment II.
  • the second polynucleotide may also have a recognition site for an endonuclease (eg, a restriction endonuclease) at the 5' end and/or the 3' end.
  • the second polynucleotide may comprise the structure R3-reference nucleic acid fragment II-R4 in the 5' to 3' direction, wherein the R3, R4 may be recognition sites for restriction endonucleases.
  • the digested second polynucleotide may comprise the reference nucleic acid fragment II.
  • second vector polynucleotide generally refers to a polynucleotide comprising vector fragment II.
  • the second vector polynucleotide may also have a recognition site for an endonuclease (eg, a restriction endonuclease) at the 5' end and/or the 3' end.
  • the second vector polynucleotide may comprise the structure R4-vector fragment II-R1 in the 5' to 3' direction, wherein the R4, R1 may be recognition sites for restriction endonucleases.
  • the enzyme-digested second vector polynucleotide may comprise the vector fragment II.
  • the term "third polynucleotide” generally refers to a polynucleotide comprising nucleic acid fragment I'.
  • the third polynucleotide may also have a recognition site for an endonuclease (eg, a restriction endonuclease) at the 5' end and/or the 3' end.
  • the third polynucleotide may comprise the structure R5-nucleic acid fragment I'-R6 in the 5' to 3' direction, wherein the R5, R6 may be recognition sites for restriction endonucleases.
  • the enzyme-digested third polynucleotide may comprise the nucleic acid fragment I'.
  • the term "third vector polynucleotide” generally refers to a polynucleotide comprising vector fragment III.
  • the third vector polynucleotide may also have a recognition site for an endonuclease (eg, a restriction endonuclease) at the 5' end and/or the 3' end.
  • the third vector polynucleotide may comprise the structure R6-vector fragment III-R7 in the 5' to 3' direction, wherein the R6, R7 may be recognition sites for restriction endonucleases.
  • the enzyme-digested third vector polynucleotide may comprise the vector fragment III.
  • the term "fourth polynucleotide” generally refers to a polynucleotide comprising nucleic acid fragment II'.
  • the fourth polynucleotide may also have a recognition site for an endonuclease (eg, a restriction endonuclease) at the 5' end and/or the 3' end.
  • the fourth polynucleotide may comprise the structure R7-nucleic acid fragment II'-R8 in the 5' to 3' direction, wherein the R7, R8 may be recognition sites for restriction endonucleases.
  • the enzyme-digested second polynucleotide may comprise the nucleic acid fragment II'.
  • the term "fourth vector polynucleotide” generally refers to a polynucleotide comprising vector fragment IV.
  • the fourth vector polynucleotide may also have a recognition site for an endonuclease (eg, a restriction endonuclease) at the 5' end and/or the 3' end.
  • the fourth vector polynucleotide may comprise the structure R8-vector fragment IV-R5 in the 5' to 3' direction, wherein the R8, R5 may be recognition sites for restriction endonucleases.
  • the enzyme-digested fourth vector polynucleotide may comprise the vector fragment IV.
  • the term "fifth polynucleotide” generally refers to the polynucleotide comprising the reference nucleic acid fragment I.
  • the fifth polynucleotide may also have a recognition site for an endonuclease (eg, a restriction endonuclease) at the 5' end and/or the 3' end.
  • the fifth polynucleotide may comprise the structure R9-reference nucleic acid fragment I-R10 in the 5' to 3' direction, wherein the R9, R10 may be recognition sites for restriction endonucleases.
  • the enzyme-digested fifth polynucleotide may comprise the reference nucleic acid fragment I.
  • the term "fifth vector polynucleotide” generally refers to a polynucleotide comprising vector fragment V.
  • the fifth vector polynucleotide may also have a recognition site for an endonuclease (eg, a restriction endonuclease) at the 5' end and/or the 3' end.
  • the fifth vector polynucleotide may comprise the structure R10-vector fragment V-R11 in the 5' to 3' direction, wherein the R10, R11 may be recognition sites for restriction endonucleases.
  • the enzyme-digested fifth vector polynucleotide may comprise the vector fragment V.
  • the term "sixth polynucleotide” generally refers to a polynucleotide comprising nucleic acid fragment II.
  • the sixth polynucleotide may also have a recognition site for an endonuclease (eg, a restriction endonuclease) at the 5' end and/or the 3' end.
  • the sixth polynucleotide may comprise the structure R11-nucleic acid fragment II-R12 in the 5' to 3' direction, wherein the R11, R12 may be recognition sites for restriction endonucleases.
  • the enzyme-digested sixth polynucleotide may comprise the nucleic acid fragment II.
  • the term "sixth vector polynucleotide” generally refers to a polynucleotide comprising vector fragment VI.
  • the sixth vector polynucleotide may also have a recognition site for an endonuclease (eg, a restriction endonuclease) at the 5' end and/or the 3' end.
  • the sixth vector polynucleotide may comprise the structure R12-vector fragment VI-R9 in the 5' to 3' direction, wherein the R12, R9 may be recognition sites for restriction endonucleases.
  • the enzyme-digested sixth vector polynucleotide may comprise the vector fragment VI.
  • cleaved first polynucleotide generally refers to a nucleic acid molecule obtained by treating the first polynucleotide with a restriction endonuclease.
  • “Cleaved first polynucleotide” comprises nucleic acid fragment I, and ends with a specific sequence obtained after treatment with restriction endonucleases at both ends.
  • the term "cleaved first carrier polynucleotide” generally refers to a nucleic acid molecule obtained by treating the first carrier polynucleotide with a restriction endonuclease.
  • the "cleaved first vector polynucleotide” comprises the vector fragment I, and the ends with a specific sequence obtained after treatment with restriction endonucleases at both ends.
  • cleaved second polynucleotide generally refers to a nucleic acid molecule obtained by treating the second polynucleotide with a restriction endonuclease.
  • "Second polynucleotide after cleavage” comprises the reference nucleic acid fragment II, and ends with a specific sequence obtained after treatment with restriction endonucleases at both ends.
  • the term "cleaved second carrier polynucleotide” generally refers to a nucleic acid molecule obtained by treating the second carrier polynucleotide with a restriction endonuclease.
  • the "cleaved second vector polynucleotide” comprises the vector fragment II, and the ends having a specific sequence obtained after treatment with restriction endonucleases at both ends.
  • the term "cleaved third polynucleotide” generally refers to a nucleic acid molecule obtained by treating the third polynucleotide with a restriction endonuclease.
  • the "cleaved third polynucleotide” comprises the nucleic acid fragment I', and the ends having a specific sequence obtained after treatment with restriction endonucleases at both ends.
  • the term "cleaved third carrier polynucleotide” generally refers to a nucleic acid molecule obtained by treating the third carrier polynucleotide with a restriction endonuclease.
  • the "cleaved third vector polynucleotide” comprises the vector fragment III, and the ends with a specific sequence obtained after treatment with restriction endonucleases at both ends.
  • the term "cleaved fourth polynucleotide” generally refers to a nucleic acid molecule obtained by treating the fourth polynucleotide with a restriction endonuclease.
  • the "cleaved fourth polynucleotide” comprises the reference nucleic acid fragment II', and the ends having a specific sequence obtained after treatment with restriction endonucleases at both ends.
  • the term "cleaved fourth carrier polynucleotide” generally refers to a nucleic acid molecule obtained by treating the fourth carrier polynucleotide with a restriction endonuclease.
  • the "cleaved fourth vector polynucleotide” comprises the vector fragment IV, and the ends having a specific sequence obtained after treatment with restriction endonucleases at both ends.
  • the term "cleaved fifth polynucleotide” generally refers to a nucleic acid molecule obtained by treating the fifth polynucleotide with a restriction endonuclease.
  • the "cleaved fifth polynucleotide” comprises the reference nucleic acid fragment I, and the ends with a specific sequence obtained after treatment with restriction endonucleases at both ends.
  • the term "cleaved fifth carrier polynucleotide” generally refers to a nucleic acid molecule obtained by treating the fifth carrier polynucleotide with a restriction endonuclease.
  • the "cleaved fifth vector polynucleotide” comprises the vector fragment V, and the ends with a specific sequence obtained after treatment with restriction endonucleases at both ends.
  • the term "cleaved sixth polynucleotide” generally refers to a nucleic acid molecule obtained by treating the sixth polynucleotide with a restriction endonuclease.
  • the "cleaved sixth polynucleotide” comprises nucleic acid fragment II, and ends with a specific sequence obtained after treatment with restriction endonucleases at both ends.
  • the term "cleaved sixth carrier polynucleotide” generally refers to a nucleic acid molecule obtained by treating the sixth carrier polynucleotide with a restriction endonuclease.
  • the "cleaved sixth vector polynucleotide” comprises the vector fragment VI, and the ends with a specific sequence obtained after treatment with restriction endonucleases at both ends.
  • first vector to be screened generally refers to a circular nucleic acid molecule comprising nucleic acid fragment I, reference nucleic acid fragment II, vector fragment I and vector fragment II.
  • the "first vector to be screened” consists of a cut first polynucleotide, a cut second polynucleotide, a cut first vector polynucleotide and a cut The second vector polynucleotides are directionally linked.
  • the "first vector to be screened” can be expressed to form an antigen binding protein. In other cases, the "first vector to be screened” cannot be expressed to form an antigen binding protein.
  • the antigen-binding protein formed by the expression of the "first vector to be screened” has one or more of the following properties: it can bind to the target specifically bound by the reference antigen-binding protein, and the binding ability to the target is the reference More than 30% (eg, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%) of the antigen binding protein's ability to bind to the target %, 95% or more than 99%), the "first vector to be screened” can be referred to as "the first replacement vector", and the nucleic acid fragment I in the "first vector to be screened” can be referred to as nucleic acid Fragment I'.
  • the "first vector library to be screened” contains one or more first vectors to be screened.
  • first replacement vector generally refers to a circular nucleic acid molecule comprising nucleic acid fragment I', reference nucleic acid fragment II, vector fragment I and vector fragment II, and the "first replacement vector” can be expressed to form antigen binding protein, and the antigen-binding protein has one or more of the following properties: capable of binding to the target specifically bound by the reference antigen-binding protein, and the binding ability to the target is the same as that of the reference antigen-binding protein and the target. More than 30% of binding capacity (eg, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 99% above).
  • the "first replacement vector library” includes one or more "first replacement vectors” and does not include those first to be screened vectors whose expressed antigen-binding proteins do not have one or more of the following properties: capable of binding to the reference A target that binds more specifically than an antigen-binding protein, and the binding capacity to the target is more than 30% of the binding capacity of the reference antigen-binding protein to the target (e.g., 35%, 40%, 45%, 50% , 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 99% or more).
  • the term "second vector to be screened” generally refers to a circular nucleic acid molecule comprising nucleic acid fragment II, reference nucleic acid fragment I, vector fragment V and vector fragment VI.
  • the "second vector to be screened” consists of a cleaved fifth polynucleotide, a cleaved sixth polynucleotide, a cleaved fifth vector polynucleotide and a cleaved
  • the sixth vector polynucleotide is formed by directional connection.
  • the "second vector to be screened" can be expressed to form an antigen-binding protein.
  • the antigen-binding protein formed by the expression of the "second vector to be screened” has the following properties: it can bind to the target specifically bound by the reference antigen-binding protein, and the binding ability to the target is the same as that of the reference antigen-binding protein More than 30% of the ability to bind to the target (eg, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% % or more than 99%, the "second vector to be screened” can be referred to as a "second replacement vector", and the nucleic acid fragment II in the "second vector to be screened” can be referred to as nucleic acid fragment II'.
  • the "second vector library to be screened” contains one or more second vectors to be screened.
  • second replacement vector generally refers to a circular nucleic acid molecule comprising nucleic acid fragment II', reference nucleic acid fragment I, vector fragment V and vector fragment VI, and the “second replacement vector” can be expressed to form antigen binding and the antigen-binding protein has the following properties: it can bind to the target specifically bound by the reference antigen-binding protein, and the binding capacity to the target is 30% of the binding capacity of the reference antigen-binding protein to the target Above (eg, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 99% above).
  • the "second replacement vector library” includes one or more "second replacement vectors", and does not include those second vectors to be screened whose expressed antigen-binding proteins do not have the following properties: capable of binding to all The target specifically bound by the reference antigen-binding protein, and the binding capacity to the target is more than 30% of the binding capacity of the reference antigen-binding protein to the target (for example, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 99% or more).
  • double displacement vector to be screened generally refers to a circular nucleic acid molecule comprising nucleic acid fragment I', nucleic acid fragment II', vector fragment I and vector fragment II.
  • the "double-replacement vector to be screened” is usually composed of the cut first polynucleotide, the cut second polynucleotide, the cut first vector polynucleotide and the cut The second vector polynucleotides are directionally linked.
  • the "double displacement vector to be screened” can be expressed to form an antigen binding protein. In other cases, the “double displacement screening vector” cannot be expressed to form an antigen binding protein.
  • the expression product of the double displacement vector to be screened has the following properties: it can bind to the target specifically bound by the reference antigen-binding protein, and the binding capacity to the target is 30% of the binding capacity of the reference antigen-binding protein to the target. % or more (for example, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more % or more, 95% or more, 99% or more, more than 1 times, more than 1.5 times, more than 2 times, more than 2.5 times, more than 3 times or more), then the double replacement vector to be screened can be called double replacement vector .
  • the "double displacement vector library to be screened" contains one or more "double displacement vectors to be screened".
  • cleaving generally refers to contacting a restriction endonuclease and a polynucleotide under conditions that enable cleavage.
  • the cleavage generally refers to the cleavage of the bond between the carbohydrate molecule of a nucleotide and the phosphate of an adjacent nucleotide molecule, for example, the cleavage generally refers to the cleavage of a phosphodiester bond between two nucleotides. cut off.
  • the polynucleotides can produce ends of specific sequences.
  • linking generally refers to the joining together of two or more polynucleotide molecules.
  • the ligation can be accomplished by a ligase (eg, DNA ligase).
  • a ligase eg, DNA ligase
  • the 3' end of one polynucleotide is ligated to the 5' end of another polynucleotide to form a complete polynucleotide molecule.
  • Directional ligation generally refers to the ligation of two or more polynucleotide molecules together in a certain order.
  • the term "introduction” generally refers to the process of transferring or introducing an exogenous polynucleotide into a cell.
  • the cell can be a host cell.
  • the introduced cells include primary cells of the subject and progeny thereof.
  • the cells may be prokaryotic cells, eg, may be bacterial cells.
  • the cells may be eukaryotic cells, eg, mammalian cells or yeast cells.
  • linker generally refers to an agent capable of linking two or more polynucleotide molecules or fragments thereof.
  • the linker can be a polynucleotide or a fragment thereof.
  • the linkers may have different lengths.
  • the length of the linker may be 40 bp or more, 50 bp or more, 60 bp or more, 70 bp or more, 80 bp or more, 90 bp or more, 100 bp or more, 150 bp or more, 200 bp or more, or longer.
  • the linker comprises a signal peptide
  • the term "signal peptide pelB" generally refers to the signal peptide of a pectinase lyase, for example, when the antigen binding protein is a Fab.
  • the signal peptide pelB is commonly used in prokaryotic expression systems.
  • the accession number of the signal peptide pelB in GenBank may be ABS75961.1.
  • the linker does not contain a signal peptide, eg, when the antigen binding protein is an scFv.
  • the first polynucleotide can include a nucleic acid molecule encoding VH
  • the second polynucleotide can include a nucleic acid molecule encoding VL
  • the first polynucleotide The nucleotides may include nucleic acid molecules encoding VL
  • the second polynucleotide may include nucleic acid molecules encoding VH.
  • the term "light chain or fragment thereof” generally refers to an amino acid fragment that has the ability to bind to the heavy chain of the same or similar antibody.
  • the light chain or fragment thereof may comprise a light chain variable region (VL) and a light chain constant region (CL).
  • the light chain constant region can be divided into ⁇ type and ⁇ type.
  • the light chain also includes a light chain having a lambda variable region (V- ⁇ ) linked to a kappa constant region (C- ⁇ ) or a kappa variable region (V- ⁇ ) linked to a lambda constant region (C- ⁇ ). chain.
  • the term “heavy chain or fragment thereof” generally refers to an amino acid fragment that has the ability to bind to the light chain of the same or similar antibody.
  • the heavy chain or fragment thereof may possess the ability to bind to the light chain of the same or similar antibody.
  • the heavy chain or heavy chain fragment may comprise a heavy chain variable region (VH) and a heavy chain constant region (CH).
  • the heavy chain constant region may comprise a CH1 domain, a hinge region, a CH2 domain and a CH3 domain.
  • the heavy chain constant region may comprise a CH4 domain but no hinge region.
  • the "heavy chain constant region” may be a CH1, hinge region, CH2, CH3, CH4 domain or any combination thereof.
  • restriction endonuclease generally refers to an enzyme that cuts double-stranded DNA.
  • the restriction endonucleases can produce sticky ends with overhanging single-stranded DNA that can bind to DNA ligases.
  • the restriction endonuclease can have the function of recognition and restriction cleavage.
  • the cleavage site of the restriction endonuclease is at a certain distance from its recognition site.
  • the restriction endonuclease may be selected from SfiI, BsmBI and Esp3I.
  • polynucleotide generally refers to nucleotides, ie, at least two nucleotides linked together.
  • the polynucleotides can be polymers of any length, including, for example, 200, 300, 500, 1000, 2000, 3000, 5000, 7000, 10,000, 100,000, and the like.
  • the polynucleotide may contain phosphodiester linkages.
  • the term "about” generally refers to a range of 0.5%-10% above or below the specified value, such as 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, or 10%.
  • the present application combines strand displacement technology with antibody display technology (eg, phage display technology and mammalian cell display technology) to provide a method for selecting functional antigen binding proteins.
  • antibody display technology eg, phage display technology and mammalian cell display technology
  • the method includes the use of an antibody heavy chain or fragment thereof (or antibody light chain or fragment thereof) of a reference antigen binding protein, with various antibody light chains or fragments thereof (or antibody heavy chains or fragments thereof) , constructing a to-be-screened library comprising the first to-be-screened vector.
  • the first vector to be screened can be a phage display vector or a cell display vector, or any other display vector that can be selected according to actual conditions.
  • the method comprises a) providing a first polynucleotide comprising in a 5' to 3' direction R1-nucleic acid fragment I-R2, said nucleic acid fragment I capable of encoding an antigen Binding fragment I; b) providing a second polynucleotide comprising R3-reference nucleic acid fragment II-R4 in the 5' to 3' direction, the reference nucleic acid fragment II capable of encoding a reference nucleic acid fragment II Compared with the antigen-binding fragment II, the reference antigen-binding fragment II can form a reference antigen-binding protein with the reference antigen-binding fragment I encoded by the reference nucleic acid fragment I; c) providing a first carrier polynucleotide, the A carrier polynucleotide comprising the R2-carrier fragment I-R3 in the 5' to 3' direction; d) providing a second carrier polynucleotide comprising the R4-carrier in the 5' to
  • the structure of the first vector to be screened can be seen in FIG. 1 .
  • the method also includes expressing the vector to be screened, and selecting an antigen-binding protein with the following properties as a functional antigen-binding protein by comparing with a reference antigen-binding protein (or other positive control antibody): capable of binding to the reference antigen-binding protein; A target that can be bound by a specific binding protein, and the binding capacity to the target is more than 30% of the binding capacity of the reference antigen-binding protein to the target.
  • a reference antigen-binding protein or other positive control antibody
  • the nucleic acid fragment I may encode an antibody light chain or a fragment thereof
  • the reference nucleic acid fragment II may encode a heavy chain of a reference antigen binding protein or a fragment thereof
  • the carrier fragment I may comprise a linking peptide
  • the vector fragment II can be derived from a phage display vector (eg pComb3x vector).
  • the nucleic acid fragment I encodes an antibody light chain and the linker peptide comprises a nucleic acid sequence encoding the signal peptide pelB or a fragment thereof.
  • the nucleic acid fragment I encodes an antibody light chain variable region.
  • the R1 may comprise the nucleotide sequence shown in SEQ ID NO: 1
  • the R2 may comprise the nucleotide sequence shown in SEQ ID NO: 2
  • the R3 may comprise the nucleus shown in SEQ ID NO: 3 nucleotide sequence
  • the R4 may comprise the nucleotide sequence shown in SEQ ID NO:4.
  • the nucleic acid fragment I can encode an antibody light chain or a fragment thereof
  • the reference nucleic acid fragment II can encode a heavy chain of a reference antigen binding protein or a fragment thereof
  • the vector fragment I and/or the Vector fragment II can be derived from a mammalian cell expression vector (eg, the pDGB4 vector).
  • the R1 may comprise the nucleotide sequence shown in SEQ ID NO:7
  • the R2 may comprise the nucleotide sequence shown in SEQ ID NO:8
  • the R3 may comprise the nucleus shown in SEQ ID NO:5 nucleotide sequence
  • the R4 may comprise the nucleotide sequence shown in SEQ ID NO:6.
  • the nucleic acid fragment I may encode an antibody heavy chain or a fragment thereof
  • the reference nucleic acid fragment II may encode a light chain of a reference antigen binding protein or a fragment thereof
  • the carrier fragment II may comprise a linking peptide
  • the vector fragment I can be derived from a phage display vector (eg pComb3x vector).
  • the reference nucleic acid fragment II encodes an antibody light chain
  • the linker peptide comprises a nucleic acid sequence encoding the signal peptide pelB or a fragment thereof.
  • the reference nucleic acid fragment II encodes an antibody light chain variable region.
  • the R1 may comprise the nucleotide sequence shown in SEQ ID NO:3
  • the R2 may comprise the nucleotide sequence shown in SEQ ID NO:4
  • the R3 may comprise the nucleus shown in SEQ ID NO:1 nucleotide sequence
  • the R4 may comprise the nucleotide sequence shown in SEQ ID NO:2.
  • the nucleic acid fragment I may encode an antibody heavy chain or a fragment thereof
  • the reference nucleic acid fragment II may encode a light chain or a fragment thereof of a reference antigen binding protein
  • the vector fragment I and/or the Vector fragment II can be derived from a mammalian cell expression vector (eg, the pDGB4 vector).
  • the R1 may comprise the nucleotide sequence shown in SEQ ID NO:5
  • the R2 may comprise the nucleotide sequence shown in SEQ ID NO:6
  • the R3 may comprise the nucleus shown in SEQ ID NO:7 nucleotide sequence
  • the R4 may comprise the nucleotide sequence shown in SEQ ID NO:8.
  • the first vector to be screened capable of expressing the functional antigen-binding protein is called the first replacement vector, and correspondingly, the nucleic acid fragment I of the first vector to be screened capable of expressing the functional antigen-binding protein is called the nucleic acid fragment I of the first replacement vector. '.
  • the method of the present application may further include: after obtaining the nucleic acid fragment I', constructing a double-replacement vector to be screened with the nucleic acid fragment II'.
  • the nucleic acid fragment II' can be obtained by any method in the art, for example, obtained by replacing the reference antigen-binding fragment of the reference antigen-binding protein, as long as it satisfies the following conditions: it can encode the antigen-binding protein II', and the The antigen-binding fragment II' can form an antigen-binding protein with the reference antigen-binding fragment I with the following properties: can bind to the target that can be combined with the reference antigen, and the binding ability to the target is that the reference antigen can be combined More than 30% of the protein's ability to bind to the target.
  • the nucleic acid fragment II' is obtained by constructing a second vector to be screened.
  • the methods described herein further comprise a) providing a fifth polynucleotide comprising R9-reference nucleic acid fragment I-R10 in a 5' to 3' direction; b) providing a sixth polynucleotide nucleotides, the sixth polynucleotide comprising R11-nucleic acid fragment II-R12 in the 5' to 3' direction; c) providing a fifth carrier polynucleotide, the fifth carrier polynucleotide being in the 5' to 3' direction comprising the R10-vector fragment V-R11 in the 3' direction; d) providing a sixth vector polynucleotide comprising the R12-vector fragment VI-R9 in the 5' to 3' direction; e) using the restriction Endonuclease cleaves the fifth polynucleotide, the sixth polynucleotide, the fifth
  • the structure of the second vector to be screened can be seen in FIG. 3 .
  • the method also includes expressing the vector to be screened, and selecting an antigen-binding protein with the following properties as a functional antigen-binding protein by comparing with a reference antigen-binding protein (or other positive control antibody): capable of binding to the reference antigen-binding protein; A target that can be bound by a specific binding protein, and the binding capacity to the target is more than 30% of the binding capacity of the reference antigen-binding protein to the target.
  • a reference antigen-binding protein or other positive control antibody
  • nucleic acid fragment II encodes an antibody light chain or a fragment thereof or an antibody heavy chain or a fragment thereof depends on the type of the nucleic acid fragment I. As long as one of the polypeptide encoded by nucleic acid fragment II and the polypeptide encoded by nucleic acid fragment I can be an antibody light chain or a fragment thereof, and the other can be an antibody heavy chain or a fragment thereof.
  • the reference nucleic acid fragment I may encode the antibody light chain of the reference antigen binding protein or a fragment thereof
  • the nucleic acid fragment II may encode the antibody heavy chain or a fragment thereof
  • the vector fragment V may comprise a linking peptide
  • the vector fragment VI can be derived from a phage display vector (eg pComb3x vector).
  • the reference nucleic acid fragment I encodes an antibody light chain
  • the linker peptide comprises a nucleic acid sequence encoding the signal peptide pelB or a fragment thereof.
  • the reference nucleic acid fragment I encodes an antibody light chain variable region.
  • the R9 may comprise the nucleotide sequence shown in SEQ ID NO: 1
  • the R10 may comprise the nucleotide sequence shown in SEQ ID NO: 2
  • the R11 may comprise the nucleus shown in SEQ ID NO: 3 nucleotide sequence
  • the R12 may comprise the nucleotide sequence shown in SEQ ID NO:4.
  • the reference nucleic acid fragment I can encode the antibody light chain of the reference antigen binding protein or its fragment
  • the nucleic acid fragment II can encode the heavy chain or its fragment
  • the vector fragment V and/or the Vector fragment VI can be derived from a mammalian cell expression vector (eg, the pDGB4 vector).
  • the R9 may comprise the nucleotide sequence shown in SEQ ID NO:7
  • the R10 may comprise the nucleotide sequence shown in SEQ ID NO:8
  • the R11 may comprise the nucleus shown in SEQ ID NO:5 nucleotide sequence
  • the R12 may comprise the nucleotide sequence shown in SEQ ID NO:6.
  • the reference nucleic acid fragment I can encode the antibody heavy chain of the reference antigen-binding protein or a fragment thereof
  • the nucleic acid fragment II can encode the light chain of the antigen-binding protein or a fragment thereof
  • the vector fragment VI can encode Comprising a linker peptide
  • the vector fragment V can be derived from a phage display vector (eg pComb3x vector).
  • the nucleic acid fragment II encodes an antibody light chain and the linker peptide comprises a nucleic acid sequence encoding the signal peptide pelB or a fragment thereof.
  • the nucleic acid fragment II encodes an antibody light chain variable region.
  • the R9 may comprise the nucleotide sequence shown in SEQ ID NO:3
  • the R10 may comprise the nucleotide sequence shown in SEQ ID NO:4
  • the R11 may comprise the nucleus shown in SEQ ID NO:1 nucleotide sequence
  • the R12 may comprise the nucleotide sequence shown in SEQ ID NO:2.
  • the reference nucleic acid fragment I may encode an antibody heavy chain or a fragment thereof
  • the nucleic acid fragment II may encode a light chain or a fragment thereof of a reference antigen binding protein
  • the vector fragment V and/or the Vector fragment VI can be derived from a mammalian cell expression vector (eg, the pDGB4 vector).
  • the R9 may comprise the nucleotide sequence shown in SEQ ID NO:5
  • the R10 may comprise the nucleotide sequence shown in SEQ ID NO:6
  • the R11 may comprise the nucleus shown in SEQ ID NO:7 nucleotide sequence
  • the R12 may comprise the nucleotide sequence shown in SEQ ID NO:8.
  • the method described in this application further comprises: obtaining nucleic acid fragment I' and nucleic acid fragment II', and one of the polypeptide encoded by nucleic acid fragment I' and the polypeptide encoded by nucleic acid fragment II' is an antibody light chain or a fragment thereof, and the other a) an antibody heavy chain or fragment thereof; b) providing a third polynucleotide comprising R5-nucleic acid fragment I'-R6 in the 5' to 3' direction; c) providing a fourth polynucleotide nucleotides, the fourth polynucleotide comprises R7-nucleic acid fragment II'-R8 in the 5' to 3' direction, the nucleic acid fragment II' is capable of encoding an antigen binding protein II', and the antigen binding fragment II 'Can form an antigen-binding protein with the following properties with the reference antigen-binding fragment I: can bind to a target that can be combined with a reference antigen, and the binding ability with
  • the structure of the double displacement vector to be screened can be seen in Figure 2.
  • the method also includes expressing the vector to be screened, and selecting an antigen-binding protein with the following properties as a functional antigen-binding protein by comparing with a reference antigen-binding protein (or other positive control antibody): capable of binding to the reference antigen-binding protein; A target that can be bound by a specific binding protein, and the binding capacity to the target is more than 30% of the binding capacity of the reference antigen-binding protein to the target.
  • a reference antigen-binding protein or other positive control antibody
  • the nucleic acid fragment I' may encode an antibody light chain or a fragment thereof of a reference antigen binding protein
  • the nucleic acid fragment II' may encode an antibody heavy chain or a fragment thereof
  • the carrier fragment III may comprise a linking peptide
  • the vector fragment IV can be derived from a phage display vector (eg pComb3x vector).
  • the nucleic acid fragment I' encodes an antibody light chain
  • the linker peptide comprises a nucleic acid sequence encoding the signal peptide pelB or a fragment thereof.
  • the nucleic acid fragment I' encodes an antibody light chain variable region.
  • the R5 may comprise the nucleotide sequence shown in SEQ ID NO: 1
  • the R6 may comprise the nucleotide sequence shown in SEQ ID NO: 2
  • the R7 may comprise the nucleus shown in SEQ ID NO: 3 nucleotide sequence
  • the R8 may comprise the nucleotide sequence shown in SEQ ID NO:4.
  • the nucleic acid fragment I' can encode the antibody light chain or its fragment of the reference antigen binding protein
  • the nucleic acid fragment II' can encode the heavy chain or its fragment
  • the vector fragment III and/or the Vector fragment IV can be derived from a mammalian cell expression vector (eg, the pDGB4 vector).
  • the R5 may comprise the nucleotide sequence shown in SEQ ID NO:7
  • the R6 may comprise the nucleotide sequence shown in SEQ ID NO:8
  • the R7 may comprise the nucleus shown in SEQ ID NO:5 nucleotide sequence
  • the R8 may comprise the nucleotide sequence shown in SEQ ID NO:6.
  • the nucleic acid fragment I' can encode the antibody heavy chain of the reference antigen-binding protein or a fragment thereof
  • the nucleic acid fragment II' can encode the light chain of the antigen-binding protein or a fragment thereof
  • the vector fragment IV can Comprising a linker peptide
  • the vector fragment III can be derived from a phage display vector (eg pComb3x vector).
  • the nucleic acid fragment II' encodes an antibody light chain
  • the linker peptide comprises a nucleic acid sequence encoding the signal peptide pelB or a fragment thereof.
  • the nucleic acid fragment II' encodes an antibody light chain variable region.
  • the R5 may comprise the nucleotide sequence shown in SEQ ID NO:3
  • the R6 may comprise the nucleotide sequence shown in SEQ ID NO:4
  • the R7 may comprise the nucleus shown in SEQ ID NO:1 nucleotide sequence
  • the R8 may comprise the nucleotide sequence shown in SEQ ID NO:2.
  • the nucleic acid fragment I' can encode an antibody heavy chain or a fragment thereof
  • the nucleic acid fragment II' can encode a light chain of a reference antigen binding protein or a fragment thereof
  • the vector fragment III and/or the Vector fragment IV can be derived from a mammalian cell expression vector (eg, the pDGB4 vector).
  • the R5 may comprise the nucleotide sequence shown in SEQ ID NO:5
  • the R6 may comprise the nucleotide sequence shown in SEQ ID NO:6
  • the R7 may comprise the nucleus shown in SEQ ID NO:7 nucleotide sequence
  • the R8 may comprise the nucleotide sequence shown in SEQ ID NO:8.
  • the methods described herein can be used to simultaneously select functional antigen-binding proteins for multiple targets, multiple binding sites for one target.
  • multiple reference antigen-binding proteins that bind to different epitopes against the same antigen can be used simultaneously to obtain a
  • the vectors to be screened for antigen-binding fragments are used to obtain fragments (nucleic acid fragment I' or nucleic acid fragment II') encoding multiple functional antigen-binding proteins that target the same antigen but bind different epitopes.
  • multiple reference antigen-binding proteins for different antigens can also be used at the same time to obtain vectors to be screened comprising multiple reference antigen-binding fragments, so as to obtain multiple functionalities encoding different antigens Fragments of antigen binding proteins (nucleic acid fragment I' or nucleic acid fragment II').
  • the first vector library to be screened may include first vectors to be screened containing multiple reference nucleic acid fragments II, the reference nucleic acid fragments I encoding 2, 3, 4 or more species that bind the same antigen Fragments of various reference antigen binding proteins.
  • the second vector library to be screened may include second vectors to be screened containing multiple reference nucleic acid fragments I encoding 2, 3, 4 or more species that bind to the same antigen Fragments of various reference antigen binding proteins.
  • the first to-be-screened vector library may include first to-be-screened vectors containing multiple reference nucleic acid fragments II, the reference nucleic acid fragments II encoding multiple (eg, 2, 3, 4) , 5, 6, 7, 8, 9, 10 or more) antigens of different reference antigen binding protein fragments.
  • the second vector library to be screened may include second vectors to be screened containing multiple reference nucleic acid fragments I, the reference nucleic acid fragments I encode multiple (eg, 2, 3, 4) , 5, 6, 7, 8, 9, 10 or more) antigens of different reference antigen binding protein fragments.
  • a library of double-displacement vectors to be screened for one or more double-displacement vectors to be screened there can be , 9, 10 or more) antigens, e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 , 13, 14, 15, 16, 17 or more) antigen binding proteins.
  • the linker may comprise a nucleic acid sequence encoding a fragment of the signal peptide pelB, and the remaining nucleic acid sequences encoding a fragment of the signal peptide pelB may also be located in the recognition site of the polynucleotide.
  • the nucleotide at the 3' end of the nucleic acid sequence encoding the fragment of the signal peptide pelB may be located in the restriction site.
  • a nucleic acid sequence encoding a fragment of the signal peptide pelB contained in one polynucleotide can be combined with a nucleic acid sequence encoding a fragment of the signal peptide pelB contained in the other polynucleotide
  • the sequences are linked to form a nucleic acid sequence encoding the complete signal peptide pelB.
  • the linker may be about 50 to about 200 bases in length.
  • the linker can be about 50 to about 200 bases, about 50 to about 180 bases, about 50 to about 160 bases, about 50 to about 140 bases, about 50 to about 140 bases in length 120 bases, about 50 to about 100 bases, about 50 to about 90 bases, about 50 to about 80 bases, about 50 to about 75 bases, about 50 to about 70 bases, About 50 to about 60 bases.
  • the end generated after any one of the R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11 and R12 is cut by restriction endonuclease may be non- Palindromic sequence.
  • nucleic acid fragment eg, nucleic acid fragment I, Nucleic acid fragment II, nucleic acid fragment I', nucleic acid fragment II', reference nucleic acid fragment I, reference nucleic acid fragment II'
  • the end formed after the nuclease recognition site is cleaved by a restriction endonuclease may be a non-palindromic sequence to prevent self-ligation, thereby reducing unintended ligation.
  • the selection of the endonuclease recognition site can enable directional ligation of multiple fragments to improve ligation efficiency.
  • R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11 and R12 can be recognized and cleaved by the same restriction endonuclease.
  • the restriction endonuclease may be selected from SfiI, BsmBI and Esp3I.
  • the BsmBI and Esp3I can be isozymes, which can recognize the same restriction endonuclease recognition site.
  • SfiI can recognize the sequence consisting of 13 bases (5' to 3') GGCCNNNN/NGGCC (SEQ ID NO: 9), which can be digested to form an overhang at the 3' end (overhang, such as containing 3 single-stranded sequence of bases), where N can represent any of the four bases of GATC.
  • SfiI can recognize the sequence consisting of 13 bases (5' to 3') GGCCNNNN/NGGCC (SEQ ID NO: 9), which can be digested to form an overhang at the 3' end (overhang, such as containing 3 single-stranded sequence of bases), where N can represent any of the four bases of GATC.
  • BsmBI and Esp3I can recognize a 12-base sequence (5' to 3') CGTCTCN/NNNNN (SEQ ID NO: 10), which can be digested to form an overhang at the 5' end (overhang, such as containing 4-base single-stranded sequence), where N can represent any of the four bases of GATC.
  • overhang such as containing 4-base single-stranded sequence
  • N can represent any of the four bases of GATC.
  • the phage display vector or mammalian cell display vector eg, pDGB4 and/or pComb3x vector
  • the phage display vector or mammalian cell display vector can be engineered/modified.
  • one or more endonuclease recognition sites in the vector can be removed by site-directed mutagenesis.
  • one or more endonuclease recognition sites can also be added to the vector by site-directed mutagenesis.
  • the pComb3x vector can be adapted for the purposes of the present application.
  • the pComb3x vector may contain a SfiI recognition site at the 5' end and a SfiI recognition site at the 3' end.
  • the SfiI recognition site at the 3' end in the pComb3x vector may be removed by site-directed mutagenesis site.
  • the site-directed mutagenesis may not affect in-frame expression of the protein (eg, antibody heavy chain fragment and/or antibody light chain fragment) in the vector.
  • the mutation may be a nonsense mutation, such as a mutation that only changes the base sequence but does not change the amino acid sequence.
  • the vector fragment (eg, vector fragment I, vector fragment II) , Vector Fragment III, Vector Fragment IV, Vector Fragment V and Vector Fragment VI) can be derived from any vector capable of expressing the gene of interest.
  • the vector fragment may be a fragment from the display vector pDGB4 (for pDGB4 see Ivan Zhou, et al., "Four-way ligation for construction of a mammalian cell-based f ⁇ L l-length antibody display library", Acta Biochim Biophys Sin 2011, 43:232–238).
  • Vector fragments of the present application may comprise nucleotide sequences with specific functions, including, but not limited to, promoter Enhancers, enhancers, signal peptides, selectable markers (for example, can include recognition sites for enzymes, resistance genes, reporter genes, screening genes), which can be adjusted (insertion/replacement) in the vector fragment by those skilled in the art according to the desired function and/or deletions, etc., of the above-mentioned nucleotide sequences with specific functions).
  • promoter Enhancers enhancers
  • signal peptides for example, can include recognition sites for enzymes, resistance genes, reporter genes, screening genes
  • selectable markers for example, can include recognition sites for enzymes, resistance genes, reporter genes, screening genes
  • the vector fragments can be adjusted in different situations to obtain different nucleotide sequences.
  • the vector may comprise or encode one or more suitable markers (eg, markers for purification/recognition/screening), which may be, eg, His tag, Flag Tag, fluorescent proteins, selective antibiotics, and/or avidins, etc.
  • suitable markers eg, markers for purification/recognition/screening
  • Vector fragments of desired length or type for example, vector fragment I, vector fragment II, vector fragment III, vector fragment IV, Vector Fragment V and/or Vector Fragment VI).
  • the nucleic acid fragment I and the nucleic acid fragment II can be obtained from the sample material.
  • the sample material may include material derived from a peripheral blood lymphocyte sample.
  • the peripheral blood lymphocytes may be human peripheral blood lymphocytes.
  • the sample material can also be derived from any other tissues and/or cells, and is not limited to the peripheral blood lymphocyte sample.
  • the nucleic acid fragment I and the nucleic acid fragment II can be obtained from a library of antibody light chains or fragments thereof that have been constructed in the prior art, or a library of antibody heavy chains or fragments thereof that has been constructed.
  • the method comprises adding the enzyme cleavage sites described herein to both ends of one or more antibody heavy chains or fragments thereof, or one or more antibody light chains or fragments thereof.
  • various methods can be used to detect the binding ability of the expression product of the first vector to be screened, the second vector to be screened and/or the double displacement vector to be screened to the target.
  • the binding ability of the expression product of the vector to be screened and the reference antigen-binding protein or other positive controls can be compared by quantitative or non-quantitative methods.
  • the present application can be tested, for example, by known methods such as enzyme-linked immunosorbent assay (ELISA), immunoblotting (eg, Western blot), flow cytometry (eg, FACS), immunohistochemistry, immunofluorescence, and the like Activity of an antigen-binding protein to bind to a target.
  • binding affinity can be determined by surface plasmon resonance (SPR), enzyme-linked immunosorbent assay (ELISA), bound antigen precipitation, equilibrium dialysis, biofilm interference (BLI).
  • the binding affinity and KD value of the PD-1 antigen binding protein for PD-1 can be determined by biofilm interference (BLI). For example, it can be determined using an ELISA method.
  • the first carrier to be screened, the second carrier to be screened and/or the double carrier to be screened The expression product of the replacement vector and/or the reference antigen-binding protein is contacted with the target (for example, antigen), and detection is performed on the first vector to be screened, the second vector to be screened and/or the double to be screened Whether a complex is formed between the expression product of the replacement vector and the target, and whether a complex is formed between the reference antigen-binding protein and the target is detected.
  • the target for example, antigen
  • the ability to bind to the target may include the EC50 value for binding to the target, the KD value for binding to the target, the OD value for the complex formed by binding to the target, and/or the absorbance of the complex formed by binding to the target.
  • the second vector to be screened and/or the expression product of the double displacement vector to be screened bind to the target, the EC 50 value, the KD value of the target, and the OD of the complex formed by binding to the target
  • the value and/or the absorbance of the complex formed by binding to the target is the EC 50 value of the reference antibody binding to the target, the KD value of the binding target, the OD value of the complex formed by binding to the target and/or the binding formed by the target.
  • More than 30% of the absorbance of the complex eg, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99%, 100%, 110% or 120% or more
  • the expression product can specifically bind to the target.
  • the expression products of the first vector to be screened, the second vector to be screened and/or the expression product of the double displacement vector to be screened bind to the target, the EC 50 value, the KD value of the target, and the complex formed by binding to the target
  • the OD value and/or the absorbance of the complex formed in combination with the target is the absence of the first vector to be screened, the second vector to be screened, the expression product of the double displacement vector to be screened and/or the reference
  • the expression product can specifically bind to the target when it is 2 times or more (eg, 2.5 times, 3 times, or 3.5 times or more) than the negative control of the antigen-binding protein.
  • the present application provides a method for preparing the functional antigen binding protein, which comprises using the first carrier to be screened, the second carrier to be screened and/or the double displacement carrier to be screened.
  • the present application provides functional antigen-binding proteins obtained by the methods described herein.
  • amino acid sequences of the full-length light and heavy chain variable regions of the following 16 reference antibodies were obtained by literature search:
  • amino acid sequences of Selicrelumab full-length light chain and full-length heavy chain were obtained by literature search (see related sequence information in WO2018220100).
  • amino acid sequence of the full-length light chain of Selicrelumab is shown in SEQ ID NO.11
  • amino acid sequence of the full-length heavy chain of Selicrelumab is shown in SEQ ID NO.12.
  • the synthetic nucleotide sequence containing the full-length light chain is shown in SEQ ID NO.13
  • the synthetic nucleotide sequence containing the variable region of the heavy chain is shown in SEQ ID NO.14.
  • amino acid sequences of the full-length light chain and heavy chain variable regions of the 16 reference antibodies were converted into base sequences that could be expressed in E. coli, and the phage display vectors were added to both ends of the sequences with appropriate restriction enzymes. Sequence and (or) the base sequence of the signal peptide sequence, synthetic gene, inserted into the pUC57 vector (Golden Strength Biotechnology Co., Ltd.).
  • the pUC57 vector containing 16 synthetic full-length light chain base sequences was digested with SfiI to obtain 16 full-length light chain fragments, which are the first polynucleotides in Figure 1.
  • the pUC57 vector containing 16 synthetic heavy chain variable region base sequences was digested with SfiI+Esp3I double enzyme to obtain 16 heavy chain variable region fragments, which is the second polynucleotide in Figure 1.
  • the obtained 16 full-length light chain fragments (that is, the first polynucleotide of FIG. 1 of the present application) and 16 heavy chain variable region fragments (that is, the second polynucleotide of FIG. 1 of the present application) were obtained according to the reference Compare the light chain fragment and heavy chain variable region fragment corresponding to the antibody with the first carrier polynucleotide and the second carrier polynucleotide indicated in Figure 1 to make 16 4-segment ligations, sequence and analyze the cloned base sequence, and get 16 Phage display vector for positive reference antibody Fab.
  • the first carrier polynucleotide and the second carrier polynucleotide please refer to the relevant steps in the library-building patent application WO2020216191A1.
  • the obtained Selicrelumab full-length light chain fragment (the first polynucleotide) and the Selicrelumab heavy chain variable region fragment (the second polynucleotide) are combined with the first vector polynucleotide and the second vector indicated in FIG. 1 .
  • the polynucleotides were ligated into four fragments, and the cloned base sequences were sequenced and analyzed to obtain a phage display vector for the positive target antibody Selicrelumab-Fab. See the relevant steps in WO2020216191A1 for the description and preparation of the first carrier polynucleotide and the second carrier polynucleotide.
  • Example 1.6 of WO2020216191A1 using the linker assembly plasmid or the linker storage vector in Example 1.4.4 as a template, the forward primer of the linker (SEQ ID NO: WO2020216191A1) is used as a template.
  • Example 1.8 of WO2020216191A1 the display vector DDB-R1R2R5R6 prepared in Example 1.7 was digested with restriction endonuclease R7 and restriction endonuclease R8 to obtain a 3.6kb display vector fragment .
  • the phage display vectors of 16 reference antibody Fabs were introduced into TG1 bacteria (Lucigen, Cat#: 60502) to obtain TG1 bacteria carrying each reference antibody Fab phage display vector.
  • the phage display vector of the positive reference antibody Selicrelumab-Fab is introduced into the TG1 bacterium to obtain TG1 bacteria carrying the phage display vector of the reference antibody Selicrelumab-Fab.
  • Kappa light chain library and Lambda light chain library inserting fragment (the first polynucleotide) that obtains, 16 reference antibody heavy chain variable region fragments (the second polynucleotide) and Fig. 1 mark the first.
  • One carrier polynucleotide and the second carrier polynucleotide (refer to the library construction patent) are connected with 4 fragments to construct a light chain replacement library.
  • the 4 fragments were mixed in an equal ratio of 1:1:1:1, the total amount was 2345ng, and ligated at 20 degrees overnight (15 hours).
  • Transform 3 TG1 inductive bacteria the total amount of bacterial liquid is 6000 ⁇ l, and after culturing for 60 minutes at 37 degrees/250 rpm, take 10 ⁇ l of bacterial liquid for titration of ligation and transformation efficiency. Do 8 times of 10-fold dilution, take 5 ⁇ l of each dilution, and incubate overnight at 32 degrees.
  • step 6 Take 50ml of the bacterial library liquid from step 7, transfer it to a 150ml shaker flask, continue to culture at 37 degrees and 250rpm for 4 hours, collect the bacteria by centrifugation, suspend the bacteria with 4ml 2TY-Amp-7% DMSO, and divide into two tubes. Freeze at minus 80 degrees.
  • step 7 Add 3 ml of helper phage (2.9 ⁇ 10 13 /ml) to the remaining bacterial stock solution (170 ml) in step 7, stand at 37 degrees for 40 minutes, and incubate at 37 degrees and 250 rpm for 40 minutes.
  • the bacteria infected with the helper phage were collected by centrifugation, centrifuged at 3500G for 15 minutes, the supernatant was discarded, and the bacteria were resuspended in 500 ml of 2YT-Amp-Kan medium, and cultured at 30 degrees and 250 rpm overnight.
  • step 4 analyze and calculate the storage capacity of the light chain-displacing bacterial library, 1.2 ⁇ 10 9 . Centrifuge to precipitate the bacteria cultured overnight in step 10, mix 500 ml of the supernatant with 125 ml of 20% PEG-5M NaCl, ice bath for 2 hours, and then centrifuge to collect the light chain replacement phage library.
  • Vh fully human heavy chain variable region
  • the obtained 16 reference antibody light chain inserts (the first polynucleotides), the Vh library inserts (the second polynucleotides) and the first indicated in FIG. 1 are inserted.
  • the carrier polynucleotide and the second carrier polynucleotide are connected by 4 fragments to construct a light chain replacement library.
  • the 4 fragments were mixed in an equal ratio of 1:1:1:1, the total amount was 2345ng, and ligated at 20 degrees overnight (15 hours).
  • Transform 3 TG1 inductive bacteria the total amount of bacterial liquid is 6000 ⁇ l, and after culturing for 60 minutes at 37 degrees/250 rpm, take 10 ⁇ l of bacterial liquid for titration of ligation and transformation efficiency. Do 8 times of 10-fold dilution, take 5 ⁇ l of each dilution, and incubate overnight at 32 degrees.
  • step 6 Take 50ml of the bacterial library liquid from step 7, transfer it to a 150ml shaker flask, continue to culture at 37 degrees and 250rpm for 4 hours, collect the bacteria by centrifugation, suspend the bacteria with 4ml 2TY-Amp-7% DMSO, and divide into two tubes. Freeze at minus 80 degrees.
  • step 7 Add 3 ml of helper phage (2.9 ⁇ 10 13 /ml) to the remaining bacterial stock solution (170 ml) in step 7, stand at 37 degrees for 40 minutes, and incubate at 37 degrees and 250 rpm for 40 minutes.
  • the bacteria infected with the helper phage were collected by centrifugation, centrifuged at 3500G for 15 minutes, the supernatant was discarded, and the bacteria were resuspended in 500 ml of 2YT-Amp-Kan medium, and cultured at 30 degrees and 250 rpm overnight.
  • step 4 analyze and calculate the storage capacity of the heavy chain-displacing bacterial library, 1.2 ⁇ 10 9 . Centrifuge to precipitate the bacteria cultured overnight in step 10, mix 500 ml of the supernatant with 125 ml of 20% PEG-5M NaCl, ice bath for 2 hours, and then centrifuge to collect the heavy chain replacement phage library.
  • Example 4 Preparation of Tg1 bacteria carrying reference antibody (Her3/Patritumab) Fab phage display vector, construction of single reference antibody (Patritumab) light chain replacement and heavy chain replacement gene library, bacterial library and phage library
  • Example 1 Referring to the procedure of Example 1, prepare Tg1 bacteria carrying the reference antibody (Patritumab) Fab phage display vector. Among them, the relevant CDR sequences of Patritumab can be found in CN 102633881B. See US 7705130B2 for the light chain heavy chain sequence of Patritumab.
  • the light chain replacement library and heavy chain replacement library of the single reference antibody Patritumab were constructed with reference to the construction process of the multi-reference antibody light chain heavy chain replacement library.
  • the heavy chain displacement library is 2.4x10e8
  • the light chain displacement library is 4.4x 10e8. Collect all the colonies of the two bacterial banks respectively, each bank is equipped with 50ml of culture solution (2YT-0.2%glucose-Amp), and an appropriate amount of bacterial solution is added, and the OD 600 is determined to be about 0.12.
  • the light chain displacing phage pool and the heavy chain displacing phage pool were collected by centrifugation.
  • the phage library was suspended with 2ml of PBS each, and each was divided into 4 tubes and frozen at minus 80 degrees.
  • the obtained Selicrelumab light chain insert (the first polynucleotide), the fully human Vh library insert (the second polynucleotide) and the first vector polynucleus marked in Figure 1 are used.
  • nucleotides, the second vector polynucleotide is connected with 4 fragments to construct a heavy chain replacement library.
  • the 4 fragments were mixed in an equal ratio of 1:1:1:1, the total amount was 1175ng, and ligated at 20 degrees overnight (15 hours).
  • step 4 analyze and calculate the storage capacity of the heavy chain displacement library, 3.2 ⁇ 10 8 . Collect all the colonies of the two large dishes cultured overnight in step 5, and the total bacterial solution is 15ml. The OD 600 of the collected bacterial solution was determined to be 20. Take 3ml, add DMSO (final concentration 7%), divide into two tubes, and freeze at minus 80 degrees (bacterial library).
  • the bacteria infected with the helper phage were collected by centrifugation, resuspended in 100 ml of 2YT-Amp-Kana medium, and cultured at 30 degrees and 250 rpm for 8 hours. The bacteria were pelleted by centrifugation, the supernatant was collected, mixed with 25ml of 5x PEG-NaCl, and the phage was pelleted overnight at 4 degrees.
  • Freeze the heavy chain replacement phage library add 0.6ml of autoclaved 80% glycerol solution to a final concentration of 20% glycerol, mix well, divide into 4 tubes, 0.6ml/tube, and freeze at minus 80 degrees.
  • a magnetic stand (Invitrogen Cat#: 12321D) aspirated and discarded the magnetic beads, and transferred the phage library solution to a new 2ml EP tube blocked with 2% MPBST.
  • the total number of phages (output) obtained from the first round of screening of the light chain-displacing phage library was calculated to be 8.8 x 10 8 .
  • the phage library obtained from the first round of screening was collected by packaging and amplifying the precipitation:
  • the phage library obtained in the third round of screening was collected by packaging, amplifying the precipitation, and the process was the same as that in the first round.
  • IPTG induction medium 2YT-Amp-2mM-IPTG, 40ml per deep-well plate, add induction medium (400 ⁇ l/well) to the deep-well plate (final IPTG concentration 1mM) that has been inoculated for 6 hours.
  • CD40-specific antigen coating solution (9.5ml ddH 2 O+0.5ml 20x coating solution+10 ⁇ g CD40 antigen without biotin labeling), coat 1 ELISA plate (100 ⁇ l/well), and coat at 4 degrees overnight.
  • the liquid-phase magnetic bead method was used to screen heavy chain-displacing phages, and the screening process was the same as the first-round screening process of the light chain-displacing phage library.
  • the antigen concentration was 1 ⁇ g/400 ⁇ l
  • the final eluted neutralizing phage solution was 540 ⁇ l.
  • Take 400 ⁇ l of the eluted neutralization solution to infect 1 ml of TG1 bacteria take 10 ⁇ l of the bacterial solution for titration, take 1 ml of the bacterial solution and spread it on a large dish, and place the rest of the bacterial solution on another large dish, and culture at 32 degrees overnight.
  • the total number of phages (output) from the first round of screening of the heavy chain displacement phage library was 8.5 x 10 5 .
  • the heavy chain displacement phage library obtained in the first round of screening was collected by packaging, amplifying and precipitation:
  • the basic process is the same as the packaging, amplification, and precipitation collection process of the light chain-displacing phage library obtained in the first round of screening. It is briefly described as follows:
  • the bacteria were collected by centrifugation, resuspended in 100 ml of 2YT-Amp-Kana medium, and incubated at 30 degrees for 8 hours.
  • the culture supernatant was collected by centrifugation, mixed with 25 ml of 5 x PEG-NaCl, and the phage was precipitated overnight at 4 degrees.
  • the first round of inoculation of the heavy chain displacement phage library was to screen colonies spread in a large plate of 0.4 ml of bacterial solution (a deep well plate).
  • the screening procedure is the same as the analysis screening for light chain displacement clones.
  • the clones with an ELISA reading greater than 0.8 were sent for sequencing and analyzed, and 28 clones positive for heavy chain replacement were obtained, which were frozen at minus 80 degrees.
  • Example 6 Thaw the 37 light chain replacement positive clones (Example 6) and 28 heavy chain replacement positive clones (Example 7) at room temperature, take 5 ⁇ l and mix them to obtain CD40-LC-ZH-M37 bacteria liquid and CD40 -VH-ZH-M28 bacterial liquid. Take 50 ⁇ l of mixed bacterial solution + 500 ⁇ l of 2YT-Amp each, put them in a large dish after mixing, and culture at 32 degrees overnight.
  • the carrier DNAs of CD40-VH-ZH-M28 (26 ⁇ g) and CD40-LC-ZH-M37 (32 ⁇ g) were extracted.
  • CD40-VH-ZH-M28 vector DNA 5 ⁇ g was digested with Esp3I and SfiI, and the M28-VH fragment (324 ng) was purified by electrophoresis analysis (see Figure 2, the fourth polynucleotide).
  • CD40-LC-ZH-M37 vector DNA 5 ⁇ g was digested with SfiI, and the M37-LC fragment (432 ng) was purified by electrophoresis analysis (see Figure 2, the third polynucleotide).
  • the prepared M37-LC insert (third polynucleotide), M28-VH insert (fourth polynucleotide) and the third carrier polynucleotide and the fourth carrier polynucleotide indicated in Figure 2 were prepared as 4 Fragments were ligated to construct a light chain heavy chain double replacement gene.
  • the 4 fragments were mixed in an equal ratio of 1:1:1:1, the total amount was 596ng, and the ligation was performed at 20 degrees for 4 hours.
  • the ligation product was purified to obtain a 450 ng light chain heavy chain double displacement gene pool.
  • the analytical screening procedure is the same as for single displacement clones.
  • Antibody expression number Antibody expression type ELISA reading positive antibody Selicrelumab 2.923 DDBK003-2 light chain replacement 3.148 DDBK003-3 light chain replacement 2.872 DDBK003-4 light chain replacement 2.903 DDBK003-5 light chain replacement 3.11 DDBK003-6 light chain replacement 3.224 DDBK003-7 light chain replacement 3.099 DDBK003-9 heavy chain replacement 3.205 DDBK003-10 heavy chain replacement 3.13 DDBK003-11 heavy chain replacement 3.175 DDBK003-12 heavy chain replacement 3.222 DDBK003-13 heavy chain replacement 3.326 DDBK003-14 light chain heavy chain double replacement 2.025 DDBK003-15 light chain heavy chain double replacement 1.839 DDBK003-16 light chain heavy chain double replacement 193
  • the antibodies were co-cultured with human PBMC for five days (antibody concentration 100 nM), the IFN- ⁇ concentration (pg/ml) in the culture supernatant was detected, and the agonism of 15 antibodies was analyzed active.
  • the results showed that compared with the positive antibody Selicrelumab (#1), all 14 screened antibodies showed different degrees of agonistic activity, among which the agonistic activity of #2, 3, 4, 5, 6, 7 and #16 was the same as that of the positive control. Antibodies are equivalent.
  • Two light chain replacement clones #2, #3; two heavy chain replacement clones, #12, #13; two light chain heavy chain double replacement clones, #14, #16 The amino acid sequence alignment shows that, with the positive control Compared with the corresponding light chain or heavy chain amino acid sequence of the antibody Selicrelumab, the screened light chain (light chain replacement clone), heavy chain (heavy chain replacement clone), light chain and heavy chain (light chain heavy chain double replacement clone), The amino acid sequences of the CDR regions differ significantly. See Table 2.
  • a Patritumab light chain-displacing phage library (Example 4) was selected for the first round of screening, and the total number of obtained light chain-displacing phages (output) was 1 ⁇ 10 5 .
  • the total number of light chain displacing phages (output) in the third round of screening was 2.2 ⁇ 10 7 .
  • Inoculate light chain replacement phage library clones 2 deep-well plates, cultivate overnight at 32 degrees and 250 rpm, and induce Fab expression with IPTG.
  • Her3 antigen-specific light chain replacement positive clones were screened by ELISA analysis. A total of 51 clones with a high OD 405 were sent for sequencing, and 28 unique light chain replacement positive clones were obtained.
  • Resuscitate gastric cancer organoids (3-27-T), culture for 7 days; collect gastric cancer organoids, wash and remove Matrigel, suspend to appropriate volume with phenol red-free D-Hanks suspension, suspend and mix well; dispense into 96-well plates , 50 ⁇ L per well.
  • the antibody-coupling reagent mixture was added to the 96-well plate that had been packed with gastric cancer organoids, 50 ⁇ l of enzyme well, and incubated at room temperature for 60 minutes.
  • the results are shown in Figure 5.
  • the results showed that the four antibodies DDBK004-2, DDBK004-3, DDBK004-7, and DDBK004-13 had green fluorescence, indicating endocytosis activity, but weaker than the positive control; the fluorescence intensity of DDBK004-11 was comparable to the positive control, indicating that this The endocytosis activity of the antibody was comparable to that of the positive antibody; the fluorescence intensity of DDBK004-9 was the strongest, which was higher than that of the positive control, indicating that the endocytosis activity of this antibody was higher than that of the positive control.
  • Example 12 Screening of TIGIT antigen-specific reference antibody Tiragolumab light chain replacement positive clones, heavy chain replacement positive clones and double replacement positive clones, and analyzing the biological functions of positive clones
  • Antigens were prepared with reference to Example 6, and TIGIT antigen-specific light chain displacement positive clones and heavy chain displacement positive clones were screened from the light chain displacement phage library and the heavy chain displacement phage library.
  • light chain replacement unique sequence positive clones and heavy chain replacement unique sequence positive clones were selected to prepare unique sequence light chain fragments (see Figure 2, the third polynucleotide) and heavy chain fragments (see Figure 2, No. 2).
  • Four polynucleotides connected with the third carrier polynucleotide and the fourth carrier polynucleotide indicated in Figure 2 to make 4 fragments to construct the light and heavy chain double replacement gene library, bacterial library and phage library, and screened to obtain double replacement unique sequences positive clone.
  • Antibody expression number Screening clone numbers Antibody type ELISA OD 405 reading 1 DDBJY38/39 positive control 0.499-2.867 2 TT128 light chain replacement 2.949 3 TT261 light chain replacement 3.349 4 TT194 light chain replacement 2.89 5 TT233 light chain replacement 3.139 6 TT216 light chain replacement 3.122 7 TT210 light chain replacement 2.84 8 TT174 light chain replacement 3.249 9 TT255 light chain replacement 3.173 10 TT321 heavy chain replacement 0.547 11 TT335 heavy chain replacement 0.669 12 TT357 heavy chain replacement 0.471 13 TT364 heavy chain replacement 1.165 14 TT385 heavy chain replacement 0.474 15 TT397 Double replacement of light and heavy chains 0.91 16 TT400 Double replacement of light and heavy chains 0.452
  • Tiragolumab The amino acid sequence of Tiragolumab can be found in WO2009126688A2.
  • TIGIT antibody combined with PD-1 antibody (Pembrolizomab) on non-small cell lung cancer organoids was observed experimentally. Based on the results of multiple preliminary experiments, a total of 5 antibodies numbered #5, 10, 12, 14, and 15 in Table 4 showed different degrees of killing activity. In order to compare and further confirm the results of the preliminary experiment, the experiment was divided into two groups of TIGIT/PD-1 antibody combination (1-8) and TIGIT antibody alone (9-16), each with 8 wells.
  • Count PBMC (4-11-PBMC), calculate the viability and cell number, collect and wash, and suspend and adjust with T cell culture medium (RPMI1640, 10% FBS, 1% double antibody, 2mM glutamine, IL2) To the appropriate concentration, divided into 96-well U-plate, 5x10 3 PBMC/well.
  • T cell culture medium RPMI1640, 10% FBS, 1% double antibody, 2mM glutamine, IL2
  • TIGIT antibodies #5, #10, #12, #14 and #15 combined with PD-1 antibody (PD1+005, PD1+010, PD1+012, PD1+014, PD1+015 ), the killing activity against non-small cell lung cancer organoids was comparable to that of the positive control (PD1+P), and obvious killing activity was seen on day 11 (D11).

Abstract

一种选择功能性抗原结合蛋白的方法，其包括通过噬菌体展示技术和/或细胞展示技术，使用已知序列和功能的参比抗原结合蛋白的轻链或其片段，或参比抗原结合蛋白的重链或其片段构建表达载体，从而选择与参比抗原结合蛋白结合相同表位的功能性抗原结合蛋白。还提供了通过所述方法得到的功能性抗原结合蛋白。

Description

用于筛选功能性抗原结合蛋白的载体和方法 技术领域
本申请涉及生物医药领域，具体的涉及一种构建表达抗原结合蛋白的载体，和功能性抗原结合蛋白的筛选方法。
背景技术
目前，在抗体工业中，应用较广的获得具有希望性质的功能性抗体或其抗原结合片段的方法主要有杂交瘤技术和抗体库技术。但是，杂交瘤技术存在候选克隆数量少、阳性克隆易丢失的问题，且挑选阳性克隆，尤其是复杂的功能筛选，需大量的时间和工作量。抗体库技术是指利用基因工程的方法将抗体重链和轻链的可变区基因克隆到质粒或噬菌体中并表达，然后利用不同抗原筛选出携带特异性抗体基因的克隆，其主要包括噬菌体展示技术和酵母表面展示技术。抗体库技术大大提高了库容，但是，目标抗原一般具有多个(例如，几个，几十个，甚至几百个)抗原决定簇，但具有所期望的生物功能的抗原决定簇可能只有一个或者几个。筛选针对目标靶点的抗原特异性抗体或其抗原结合片段时，并不知道哪个抗原决定簇具有所期望的生物学功能。现有技术通常先获得一大批抗原特异性抗体或其抗原结合片段，再逐个分析鉴定，找出与特定抗原决定簇结合、具有所期望生物学功能的抗体或其抗原结合片段，仍需要较长的时间和较大的工作量，且筛选效果不佳。因此，需要新的抗体或其抗原结合片段发现技术，以提高先导分子的质量、数量及多样性，加快药物开发速度，提高开发成功率。
一方面，本申请提供了一种选择功能性抗原结合蛋白的方法，其包括，a)提供第一多核苷酸，所述第一多核苷酸以5’至3’方向包含R1-核酸片段I-R2，所述核酸片段I能够编码抗原结合片段I；b)提供第二多核苷酸，所述第二多核苷酸以5’至3’方向包含R3-参比核酸片段II-R4，所述参比核酸片段II能够编码参比抗原结合片段II，所述参比抗原结合片段II能够与由参比核酸片段I编码的参比抗原结合片段I形成参比抗原结合蛋白；c)提供第一载体多核苷酸，所述第一载体多核苷酸以5’至3’方向包含R2-载体片段I-R3；d)提供第二载体多核苷酸，所述第二载体多核苷酸以5’至3’方向包含R4-载体片段II-R1；e)用限制性核酸内切酶切割所述第一多核苷酸、所述第二多核苷酸、所述第一载体多核苷酸和所述第二载体多核苷酸，得到切割后的第一多核苷酸、切割后的第二多核苷酸、切割后的第一载体多核 苷酸和切割后的第二载体多核苷酸；f)混合所述切割后的第一多核苷酸、所述切割后的第二多核苷酸、所述切割后的第一载体多核苷酸和所述切割后的第二载体多核苷酸，从而使得其能够定向连接而环化形成第一待筛选载体；g)使所述第一待筛选载体表达，选择能够表达具有以下性质的表达产物的第一待筛选载体为第一置换载体：能够结合所述参比结合蛋白能够结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上；h)从所述第一置换载体获得所述功能性抗原结合蛋白；其中，所述R1、R2、R3和R4各自独立地为限制性内切核酸酶识别位点。
在某些实施方式中，所述方法包括用特异性识别所述R1和R2的限制性核酸内切酶切割所述第一多核苷酸，获得所述切割后的第一多核苷酸。
在某些实施方式中，所述方法包括用特异性识别所述R3和R4的限制性核酸内切酶切割所述第二多核苷酸，获得所述切割后的第二多核苷酸。
在某些实施方式中，所述方法包括用特异性识别所述R2和R3的限制性核酸内切酶切割所述第一载体多核苷酸，获得所述切割后的第一载体多核苷酸。
在某些实施方式中，所述方法包括用特异性识别所述R4和R1的限制性核酸内切酶切割所述第二载体多核苷酸，获得所述切割后的第二载体多核苷酸。
在某些实施方式中，所述R1经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R2、R3和R4中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
在某些实施方式中，所述R2经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R1、R3和R4中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
在某些实施方式中，所述R3经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R1、R2和R4中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
在某些实施方式中，所述R4经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R1、R2和R3中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
在某些实施方式中，所述限制性内切核酸酶选自SfiI和BsmBI。
在某些实施方式中，所述方法包括将所述第一待筛选载体导入细胞，使所述第一待筛选载体表达。
在某些实施方式中，所述方法包括将所述第一待筛选载体导入细菌，制备包含一个或多个所述第一待筛选载体的噬菌体库，由所述噬菌体库获得所述功能性抗原结合蛋白。
在某些实施方式中，所述载体片段I包含连接子，且所述载体片段II源自展示载体。
在某些实施方式中，所述核酸片段I编码抗体轻链或其片段，所述载体片段I包含所述连接子，所述参比核酸片段II编码抗体重链或其片段，且所述载体片段II源自所述展示载体。
在某些实施方式中，所述R1包含SEQ ID NO:1所示的核苷酸序列。
在某些实施方式中，所述R2包含SEQ ID NO:2所示的核苷酸序列。
在某些实施方式中，所述R3包含SEQ ID NO:3所示的核苷酸序列。
在某些实施方式中，所述R4包含SEQ ID NO:4所示的核苷酸序列。
在某些实施方式中，所述载体片段II包含连接子，且所述载体片段I源自展示载体。
在某些实施方式中，所述核酸片段I编码抗体重链或其片段，所述载体片段I源自所述展示载体，所述参比核酸片段II编码抗体轻链或其片段，且所述载体片段II包含所述连接子。
在某些实施方式中，所述R1包含SEQ ID NO:3所示的核苷酸序列。
在某些实施方式中，所述R2包含SEQ ID NO:4所示的核苷酸序列。
在某些实施方式中，所述R3包含SEQ ID NO:1所示的核苷酸序列。
在某些实施方式中，所述R4包含SEQ ID NO:2所示的核苷酸序列。
在某些实施方式中，所述展示载体源自pComb3x载体。
在某些实施方式中，所述连接子包含编码信号肽pelB或其片段的核酸序列。
在某些实施方式中，所述连接子的长度为约50至约200个碱基。
在某些实施方式中，所述方法包括将所述第一待筛选载体导入细菌，从所述细菌得到所述第一待筛选载体的DNA，将所述第一待筛选载体的DNA导入细胞；由所述细胞获得所述功能性抗原特异性结合多肽。
在某些实施方式中，所述细胞为哺乳动物细胞。
在某些实施方式中，所述载体片段I和/或所述载体片段II源自哺乳动物细胞表达载体。
在某些实施方式中，所述哺乳动物细胞表达载体源自pDGB4。
在某些实施方式中，所述核酸片段I编码抗体轻链或其片段，且所述参比核酸片段II编码抗体重链或其片段。
在某些实施方式中，所述R1包含SEQ ID NO:7所示的核苷酸序列。
在某些实施方式中，所述R2包含SEQ ID NO:8所示的核苷酸序列。
在某些实施方式中，所述R3包含SEQ ID NO:5所示的核苷酸序列。
在某些实施方式中，所述R4包含SEQ ID NO:6所示的核苷酸序列。
在某些实施方式中，所述核酸片段I编码抗体重链或其片段，且所述参比核酸片段II编码抗体轻链或其片段。
在某些实施方式中，所述R1包含SEQ ID NO:5所示的核苷酸序列。
在某些实施方式中，所述R2包含SEQ ID NO:6所示的核苷酸序列。
在某些实施方式中，所述R3包含SEQ ID NO:7所示的核苷酸序列。
在某些实施方式中，所述R4包含SEQ ID NO:8所示的核苷酸序列。
在某些实施方式中，所述方法包括：a)提供第三多核苷酸，所述第三多核苷酸以5’至3’方向包含R5-核酸片段I’-R6；b)提供第四多核苷酸，所述第四多核苷酸以5’至3’方向包含R7-核酸片段II’-R8，所述核酸片段II’能够编码抗原结合蛋白II’，且所述抗原结合片段II’能够与所述参比抗原结合片段I形成具有以下性质的抗原结合蛋白：能够结合参比抗原结合蛋白能够结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上；c)提供第三载体多核苷酸，所述第三载体多核苷酸以5’至3’方向包含R6-载体片段III-R7；d)提供第四载体多核苷酸，所述第四载体多核苷酸以5’至3’方向包含R8-载体片段IV-R5；e)用限制性核酸内切酶切割所述第三多核苷酸、所述第四多核苷酸、所述第三载体多核苷酸和所述第四载体多核苷酸，得到切割后的第三多核苷酸、切割后的第四多核苷酸、切割后的第三载体多核苷酸和切割后的第四载体多核苷酸；f)混合所述切割后的第三多核苷酸、所述切割后的第四多核苷酸、所述切割后的第三载体多核苷酸和所述切割后的第四载体多核苷酸，从而使得其能够定向连接而环化形成双置换待筛选载体；g)使所述双置换待筛选载体表达，选择能够表达具有以下性质的表达产物的双置换待筛选载体为双置换载体：能够结合所述靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上；h)从所述双置换载体获得所述功能性抗原结合蛋白；其中，所述R5、R6、R7和R8各自独立地为所述限制性内切核酸酶识别位点。
在某些实施方式中，所述方法包括用特异性识别所述R5和R6的限制性核酸内切酶切割所述第三多核苷酸，获得所述切割后的第三多核苷酸。
在某些实施方式中，所述方法包括用特异性识别所述R7和R8的限制性核酸内切酶切割所述第四多核苷酸，获得所述切割后的第四多核苷酸。
在某些实施方式中，所述方法包括用特异性识别所述R6和R7的限制性核酸内切酶切割所述第三载体多核苷酸，获得所述切割后的第三载体多核苷酸。
在某些实施方式中，所述方法包括用特异性识别所述R8和R5的限制性核酸内切酶切割所述第四载体多核苷酸，获得所述切割后的第四载体多核苷酸。
在某些实施方式中，所述R5经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R6、R7和R8中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
在某些实施方式中，所述R6经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R5、R7和R8中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
在某些实施方式中，所述R7经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R5、R6和R8中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
在某些实施方式中，所述R8经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R5、R6和R7中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
在某些实施方式中，所述限制性内切核酸酶选自SfiI和BsmBI。
在某些实施方式中，所述方法包括将所述双置换待筛选载体导入细胞，使所述双置换待筛选载体表达。
在某些实施方式中，所述方法包括将所述双置换待筛选载体导入细菌，制备包含一个或多个所述双置换待筛选载体的噬菌体库，由所述噬菌体库获得所述功能性抗原结合蛋白。
在某些实施方式中，所述载体片段III包含连接子，且所述载体片段IV源自展示载体。
在某些实施方式中，所述核酸片段I’编码抗体轻链或其片段，所述载体片段III包含所述连接子，所述核酸片段II’编码抗体重链或其片段，且所述载体片段IV源自所述展示载体。
在某些实施方式中，所述R5包含SEQ ID NO:1所示的核苷酸序列。
在某些实施方式中，所述R6包含SEQ ID NO:2所示的核苷酸序列。
在某些实施方式中，所述R7包含SEQ ID NO:3所示的核苷酸序列。
在某些实施方式中，所述R8包含SEQ ID NO:4所示的核苷酸序列。
在某些实施方式中，所述载体片段IV包含连接子，且所述载体片段III源自展示载体。
在某些实施方式中，所述核酸片段I’编码抗体重链或其片段，所述载体片段III源自所述展示载体，所述核酸片段II’编码抗体轻链或其片段，且所述载体片段IV包含所述连接子。
在某些实施方式中，所述R5包含SEQ ID NO:3所示的核苷酸序列。
在某些实施方式中，所述R6包含SEQ ID NO:4所示的核苷酸序列。
在某些实施方式中，所述R7包含SEQ ID NO:1所示的核苷酸序列。
在某些实施方式中，所述R8包含SEQ ID NO:2所示的核苷酸序列。
在某些实施方式中，所述展示载体源自pComb3x载体。
在某些实施方式中，所述连接子包含编码信号肽pelB或其片段的核酸序列。
在某些实施方式中，所述连接子的长度为约50至约200个碱基。
在某些实施方式中，所述方法包括将所述双展示待筛选载体导入细菌，从所述细菌得到所述双展示待筛选载体的DNA，将所述双展示待筛选载体的DNA导入细胞；由所述细胞获得所述功能性抗原特异性结合多肽。
在某些实施方式中，所述细胞为哺乳动物细胞。
在某些实施方式中，所述载体片段III和/或所述载体片段IV源自哺乳动物表达载体。
在某些实施方式中，所述哺乳动物表达载体源自pDGB4。
在某些实施方式中，所述核酸片段I’编码抗体轻链或其片段，且所述核酸片段II’编码抗体重链或其片段。
在某些实施方式中，所述R5包含SEQ ID NO:7所示的核苷酸序列。
在某些实施方式中，所述R6包含SEQ ID NO:8所示的核苷酸序列。
在某些实施方式中，所述R7包含SEQ ID NO:5所示的核苷酸序列。
在某些实施方式中，所述R8包含SEQ ID NO:6所示的核苷酸序列。
在某些实施方式中，所述核酸片段I’编码抗体重链或其片段，且所述核酸片段II’编码抗体轻链或其片段。
在某些实施方式中，所述R5包含SEQ ID NO:5所示的核苷酸序列。
在某些实施方式中，所述R6包含SEQ ID NO:6所示的核苷酸序列。
在某些实施方式中，所述R7包含SEQ ID NO:7所示的核苷酸序列。
在某些实施方式中，所述R8包含SEQ ID NO:8所示的核苷酸序列。
在某些实施方式中，所述方法包括：a)提供第五多核苷酸，所述第五多核苷酸以5’至3’方向包含R9-参比核酸片段I-R10；b)提供第六多核苷酸，所述第六多核苷酸以5’至3’方 向包含R11-核酸片段II-R12；c)提供第五载体多核苷酸，所述第五载体多核苷酸以5’至3’方向包含R10-载体片段V-R11；d)提供第六载体多核苷酸，所述第六载体多核苷酸以5’至3’方向包含R12-载体片段VI-R9；e)用限制性核酸内切酶切割所述第五多核苷酸、所述第六多核苷酸、所述第五载体多核苷酸和所述第六载体多核苷酸，得到切割后的第五多核苷酸、切割后的第六多核苷酸、切割后的第五载体多核苷酸和切割后的第六载体多核苷酸；f)混合所述切割后的第五多核苷酸、所述切割后的第六多核苷酸、所述切割后的第五载体多核苷酸和所述切割后的第六载体多核苷酸，从而使得其能够定向连接而环化形成第二待筛选载体；g)使所述第二待筛选载体表达，选择能够表达具有以下性质的表达产物的第二待筛选载体为第二置换载体：能够结合所述参比结合蛋白能够结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上；h)选择所述第二置换载体的核酸片段II为所述核酸片段II’；其中，所述R9、R10、R11和R12各自独立地为限制性内切核酸酶识别位点。
在某些实施方式中，所述方法包括用特异性识别所述R9和R10的限制性核酸内切酶切割所述第五多核苷酸，获得所述切割后的第五多核苷酸。
在某些实施方式中，所述方法包括用特异性识别所述R11和R12的限制性核酸内切酶切割所述第六多核苷酸，获得所述切割后的第六多核苷酸。
在某些实施方式中，所述方法包括用特异性识别所述R10和R11的限制性核酸内切酶切割所述第五载体多核苷酸，获得所述切割后的第五载体多核苷酸。
在某些实施方式中，所述方法包括用特异性识别所述R12和R9的限制性核酸内切酶切割所述第六载体多核苷酸，获得所述切割后的第六载体多核苷酸。
在某些实施方式中，所述R9经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R10、R11和R12中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
在某些实施方式中，所述R10经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R11、R12和R9中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
在某些实施方式中，所述R11经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R9、R10和R12中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
在某些实施方式中，所述R12经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R9、R10和R11中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
在某些实施方式中，所述限制性内切核酸酶选自SfiI和BsmBI。
在某些实施方式中，所述方法包括将所述第二待筛选载体导入细胞，使所述第二待筛选载体表达。
在某些实施方式中，所述方法包括将所述第二待筛选载体导入细菌，制备包含一个或多个所述第二待筛选载体的噬菌体库，由所述噬菌体库获得所述功能性抗原结合蛋白。
在某些实施方式中，所述载体片段V包含连接子，且所述载体片段VI源自展示载体。
在某些实施方式中，所述参比核酸片段I编码抗体轻链或其片段，所述载体片段V包含所述连接子，所述核酸片段II编码抗体重链或其片段，且所述载体片段VI源自所述展示载体。
在某些实施方式中，所述R9包含SEQ ID NO:1所示的核苷酸序列。
在某些实施方式中，所述R10包含SEQ ID NO:2所示的核苷酸序列。
在某些实施方式中，所述R11包含SEQ ID NO:3所示的核苷酸序列。
在某些实施方式中，所述R12包含SEQ ID NO:4所示的核苷酸序列。
在某些实施方式中，所述载体片段VI包含连接子，且所述载体片段V源自展示载体。
在某些实施方式中，所述参比核酸片段I编码抗体重链或其片段，所述载体片段V源自所述展示载体，所述核酸片段II编码抗体轻链或其片段，且所述载体片段VI包含所述连接子。
在某些实施方式中，所述R9包含SEQ ID NO:3所示的核苷酸序列。
在某些实施方式中，所述R10包含SEQ ID NO:4所示的核苷酸序列。
在某些实施方式中，所述R11包含SEQ ID NO:1所示的核苷酸序列。
在某些实施方式中，所述R12包含SEQ ID NO:2所示的核苷酸序列。
在某些实施方式中，所述展示载体源自pComb3x载体。
在某些实施方式中，所述连接子包含编码信号肽pelB或其片段的核酸序列。
在某些实施方式中，所述连接子的长度为约50至约200个碱基。
在某些实施方式中，所述方法包括将所述第二待筛选载体导入细菌，从所述细菌得到所述第二待筛选载体的DNA，将所述第二待筛选载体的DNA导入细胞；由所述细胞获得所述功能性抗原特异性结合多肽。
在某些实施方式中，所述细胞为哺乳动物细胞。
在某些实施方式中，所述载体片段V和/或所述载体片段VI源自哺乳动物表达载体。
在某些实施方式中，所述哺乳动物表达载体源自pDGB4。
在某些实施方式中，所述参比核酸片段I编码抗体轻链或其片段，且所述参比片段II编码抗体重链或其片段。
在某些实施方式中，所述R9包含SEQ ID NO:7所示的核苷酸序列。
在某些实施方式中，所述R10包含SEQ ID NO:8所示的核苷酸序列。
在某些实施方式中，所述R11包含SEQ ID NO:5所示的核苷酸序列。
在某些实施方式中，所述R12包含SEQ ID NO:6所示的核苷酸序列。
在某些实施方式中，所述参比核酸片段I编码抗体重链或其片段，且所述核酸片段II编码抗体轻链或其片段。
在某些实施方式中，所述R9包含SEQ ID NO:5所示的核苷酸序列。
在某些实施方式中，所述R10包含SEQ ID NO:6所示的核苷酸序列。
在某些实施方式中，所述R11包含SEQ ID NO:7所示的核苷酸序列。
在某些实施方式中，所述R12包含SEQ ID NO:8所示的核苷酸序列。
在某些实施方式中，所述抗原结合蛋白包括抗体或抗体片段。
在某些实施方式中，所述抗体片段包含scFv，Fab，Fab’，(Fab) 2和/或(Fab’) 2。
在某些实施方式中，所述定向连接包括使用连接酶。
在某些实施方式中，所述连接酶为DNA连接酶。
另一方面，本申请提供了制备抗原结合蛋白的方法，其包括在所述的第一置换载体、所述的第二置换载体和/或所述的双置换载体表达的条件下，使所述的第一置换载体、所述的第二置换载体和/或所述的双置换载体表达。
另一方面，本申请提供了根据所述方法制备的第一置换载体。
另一方面，本申请提供了根据所述方法制备的第二置换载体。
另一方面，本申请提供了根据所述方法制备的双置换载体。
另一方面，本申请提供了根据所述方法制备得到的功能性抗原结合蛋白。
发明内容
本申请提供了一种选择功能性抗原结合蛋白的方法，所述方法包括利用已知序列和/或功能的参比抗原结合蛋白的参比抗原结合片段(例如，参比抗原结合片段I和/或参比抗原结合片段II)构建载体(例如，所述双置换待筛选载体、所述第一待筛选载体和/或所述第二 待筛选载体)，使所述载体表达，然后根据所述载体的表达产物与所述参比抗原结合蛋白所能识别的靶标的结合活性，获得所述功能性抗原结合蛋白。本申请还提供了构建所述载体的方法，以及通过所述载体获得的功能性抗原结合蛋白。本申请通过现有技术中已知序列和/或功能的参比抗原结合蛋白的轻重链或其片段，结合抗体的噬菌体展示技术或细胞表面展示技术筛选得到具有期望性质的新颖的功能性抗原结合蛋白，筛选得到的所述功能性抗原结合蛋白与参比抗原结合蛋白结合同一靶标的相同或相近表位的可能性大，具有生物活性的可能性大，筛选效率高，且筛选时间短。
本领域技术人员能够从下文的详细描述中容易地洞察到本申请的其它方面和优势。下文的详细描述中仅显示和描述了本申请的示例性实施方式。如本领域技术人员将认识到的，本申请的内容使得本领域技术人员能够对所公开的具体实施方式进行改动而不脱离本申请所涉及发明的精神和范围。相应地，本申请的附图和说明书中的描述仅仅是示例性的，而非为限制性的。
附图说明
本申请所涉及的发明的具体特征如所附权利要求书所显示。通过参考下文中详细描述的示例性实施方式和附图能够更好地理解本申请所涉及发明的特点和优势。对附图简要说明如下：
图1显示的是本申请所述第一待筛选载体的示例性结构；
图2显示的是本申请所述双置换待筛选载体的示例性结构；
图3显示的是本申请所述第二待筛选载体的示例性结构。
图4显示的是本申请所述方法获得抗体的抗体激动活性分析结果。
图5显示的是本申请所述方法获得抗体的抗体内吞活性分析结果。
图6显示的是本申请所述方法获得抗体单独施用的抗肿瘤效果。
图7显示的是本申请所述方法获得抗体联合施用的抗肿瘤效果。
具体实施方式
以下由特定的具体实施例说明本申请发明的实施方式，熟悉此技术的人士可由本说明书所公开的内容容易地了解本申请发明的其他优点及效果。
术语定义
在本申请中，术语“参比抗原结合蛋白”通常是指具有至少有一种所期望的生物学功能的抗原结合蛋白。例如，能够以高亲和力特异性结合某一靶标，能够阻断某一蛋白与特定配体的结合，和/或能够刺激免疫细胞分泌细胞因子等。参比抗原结合蛋白可以是来自现有技术中的已知氨基酸序列和/或功能的抗原结合蛋白(例如，抗体)。在某些实施方式中，所述参比抗原结合蛋白来自商业化的抗体产品和/或临床试验中的抗体。选择何种参比抗原结合蛋白(以及“参比抗原结合片段I”和/或“参比抗原结合片段II”)取决于所期望得到具有何种生物学功能的抗原结合蛋白。例如，如希望获得特异性结合PD-1的抗原结合蛋白，可以选择PD-1抗体Nivolumab、Pembrolizumab或Cemiplimab作为参比抗原结合蛋白。例如，如希望获得特异性结合PD-L1的抗原结合蛋白，可以选择PD-1抗体Atezolizumab、Avelumab或Durvalumab作为参比抗原结合蛋白。
在本申请中，术语“参比核酸片段I”通常是指能够编码参比抗原结合片段I的核酸片段。
在本申请中，术语“参比核酸片段II”通常是指能够编码参比抗原结合片段II的核酸片段。
在本申请中，术语“参比抗原结合片段I”通常是指能够形成参比抗原结合蛋白的多肽片段。所述“参比抗原结合片段I”可以是抗体重链或重链可变区，或重链片段，也可以是抗体轻链或轻链可变区，或轻链片段。
在本申请中，术语“参比抗原结合片段II”通常是指能够形成参比抗原结合蛋白的多肽片段。所述“参比抗原结合片段II”可以是抗体重链或重链可变区，或重链片段，也可以是抗体轻链或轻链可变区，或轻链片段。
“参比抗原结合片段I”可以和“参比抗原结合片段II”形成抗原结合蛋白(例如，参比抗原结合蛋白)。
在本申请中，术语“抗原结合蛋白”通常是指包含结合抗原部分的蛋白质，以及任选地允许结合抗原的部分采用促进抗原结合蛋白与抗原结合的构象的支架或骨架部分。抗原结合蛋白可典型地包含抗体轻链可变区(VL)、抗体重链可变区(VH)或上述两者，及其功能性片段。重链和轻链的可变区含有与抗原相互作用的结合结构域。抗原结合蛋白的实例包括但不限于抗体、抗原结合片段、免疫缀合物、多特异性抗体(例如双特异性抗体)、抗体片段、抗体衍生物、抗体类似物或融合蛋白等，只要它们显示出所需的抗原结合活性即可。
在本申请中，术语“抗体”通常是指对指定蛋白质或肽或其片段有反应性的免疫球蛋白。抗体可以是来自任何类的抗体，包括但不限于IgG、IgA、IgM、IgD和IgE，及来自任何亚类(例如IgG1、IgG2、IgG3、和IgG4)的抗体。抗体可具有选自例如IgG1、IgG2、IgG3、或IgG4的重链恒定区。抗体还可具有选自例如kappa(κ)或lambda(λ)的轻链。本申请的抗体可衍生自任何物种。
在本申请中，术语“抗原结合蛋白”可以指抗体分子的某部分，该部分包含氨基酸残基，该氨基酸残基与抗原相互作用并赋予抗体对于抗原的特异性和亲和力。在本申请中，术语“抗原结合蛋白”可以包含抗体或抗体片段，尤其指那些包含抗体轻链或其片段(例如，VL)和抗体重链或其片段(例如，VH)的抗体部分。在所述抗原结合蛋白中，抗体轻链或其片段(例如，VL)和抗体重链或其片段(例如，VH)可以通过连接子(例如肽连接子)在N端或C端连接，形成一条多肽链。在所述抗原结合蛋白中，抗体轻链或其片段(例如，VL)和抗体重链或其片段(例如，VH)也可以通过链间化学键(例如二硫键)连接，形成二聚体。抗原结合蛋白的实例可包括但不限于Fab，Fab’，F(ab) 2，Fv片段，F(ab’) 2，scFv，di-scFv和/或dAb。例如，所述抗原结合蛋白可以是scFv或Fab。
在本申请中，术语“Fab”通常是指由木瓜蛋白酶消化具有完整结构的抗体后(例如，去除了Fc区和铰链区)而产生两个相同的抗原结合片段。Fab可以由完整的轻链、重链可变区(VH)和重链的第一恒定结构域(CH1)组成。每个Fab可以具有单一的抗原结合位点。
本申请中，术语“scFv”通常是指抗体的一个重链可变结构域和一个轻链可变结构域通过柔性肽连接子共价连接配对形成的单价分子。
在本申请中，术语“功能性抗原结合蛋白”通常是指根据本申请的方法选择得到的具有期望功能的抗原结合蛋白。例如，能够以高亲和力特异性结合某一靶标，能够阻断某一蛋白与特定配体的结合，和/或能够刺激免疫细胞分泌细胞因子等。所述功能性抗原结合蛋白具有以下性质：能够结合本申请的参比结合蛋白能够结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上(例如，35％、40％、45％、50％、55％、60％、65％、70％、75％、80％、85％、90％、95％或99％以上)。功能性抗原结合蛋白可以包含参比抗原结合片段I和抗原结合片段II’。功能性抗原结合蛋白可以包含参比抗原结合片段II和抗原结合片段I’。功能性抗原结合蛋白可以包含抗原结合片段I’和抗原结合片段II’。
在本申请中，术语“核酸片段I”通常是指能够表达抗原结合片段I的核酸分子。在核酸片段I中，具有以下性质的核酸片段I被选择为核酸片段I’：其表达的抗原结合片段I能够与参比核酸片段II表达的参比抗原结合片段I形成抗原结合蛋白，且所述抗原结合蛋白具有一种或多种以下性质：能够结合所述参比抗原结合蛋白特异性结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上(例如，35％、40％、45％、50％、55％、60％、65％、70％、75％、80％、85％、90％、95％或99％以上)。并不是每一个核酸片段I都是核酸片段I’。并不是每一个核酸片段I表达的抗原结合片段I都能够与参比核酸片段II表达的参比抗原结合片段II形成抗原结合蛋白。
在本申请中，术语“核酸片段I’”通常是指能够表达抗原结合片段I’的核酸分子。所述核酸片段I’表达的抗原结合片段I’能够与参比核酸片段II表达的参比抗原结合片段I形成功能性抗原结合蛋白，且所述抗原结合蛋白具有一种或多种以下性质：能够结合所述参比抗原结合蛋白特异性结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上(例如，35％、40％、45％、50％、55％、60％、65％、70％、75％、80％、85％、90％、95％或99％以上)。
在本申请中，术语“核酸片段II”通常是指能够表达抗原结合片段II的核酸分子。在核酸片段II中，具有以下性质的核酸片段II被选择为核酸片段II’：其表达的抗原结合片段II能够与参比核酸片段I表达的参比抗原结合片段I形成抗原结合蛋白，且所述抗原结合蛋白具有一种或多种以下性质：：能够结合所述参比抗原结合蛋白特异性结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上(例如，35％、40％、45％、50％、55％、60％、65％、70％、75％、80％、85％、90％、95％或99％以上)。并不是每一个核酸片段II都是核酸片段II’。并不是每一个核酸片段II表达的抗原结合片段II都能够与参比核酸片段I表达的参比抗原结合片段I形成抗原结合蛋白。
在本申请中，术语“核酸片段II’”通常是指能够表达抗原结合片段II’的核酸分子。所述核酸片段II’表达的抗原结合蛋白II’能够与参比核酸片段I表达的参比抗原结合片段I形成功能性抗原结合蛋白，且所述抗原结合蛋白具有一种或多种以下性质：能够结合所述参比抗原结合蛋白特异性结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上(例如，35％、40％、45％、50％、55％、60％、65％、70％、75％、80％、85％、90％、95％或99％以上)。
在本申请中，术语“抗原结合片段I”通常是指由核酸片段I的表达产物，其由核酸片段I编码。在抗原结合片段I中，具有以下性质的抗原结合片段I可以被选择为抗原结合片段 I’：能够与参比抗原结合片段II形成抗原结合蛋白，且所述抗原结合蛋白具有一种或多种以下性质：能够结合所述参比抗原结合蛋白特异性结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上(例如，35％、40％、45％、50％、55％、60％、65％、70％、75％、80％、85％、90％、95％或99％以上)。并不是每一个抗原结合片段I都是抗原结合片段I’。所述“抗原结合片段I”可以是抗体重链或重链可变区，或重链片段，也可以是抗体轻链或轻链可变区，或轻链片段。
在本申请中，术语“抗原结合片段I’”通常是指由核酸片段I’的表达产物，其由核酸片段I’编码。抗原结合片段I’是抗原结合片段I中能够与参比抗原结合片段II结合形成功能性抗原结合蛋白，且所述抗原结合蛋白具有一种或多种以下性质：能够结合所述参比抗原结合蛋白特异性结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上(例如，35％、40％、45％、50％、55％、60％、65％、70％、75％、80％、85％、90％、95％或99％以上)。
在本申请中，术语“抗原结合片段II”通常是指由核酸片段II的表达产物，其由核酸片段II编码。在抗原结合片段II中，具有以下性质的抗原结合片段II可以被选择为抗原结合片段II’：能够与参比抗原结合片段I形成抗原结合蛋白，且所述抗原结合蛋白具有一种或多种以下性质：能够结合所述参比抗原结合蛋白特异性结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上(例如，35％、40％、45％、50％、55％、60％、65％、70％、75％、80％、85％、90％、95％或99％以上)。并不是每一个抗原结合片段II都是抗原结合片段II’。所述“抗原结合片段II”可以是抗体重链或重链可变区，或重链片段，也可以是抗体轻链或轻链可变区，或轻链片段。
在本申请中，术语“抗原结合片段II’”通常是指由核酸片段II’的表达产物，其由核酸片段II’编码。抗原结合片段II’是抗原结合片段II中能够与参比抗原结合片段I结合形成功能性抗原结合蛋白，且所述抗原结合蛋白具有一种或多种以下性质：能够结合所述参比抗原结合蛋白特异性结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上(例如，35％、40％、45％、50％、55％、60％、65％、70％、75％、80％、85％、90％、95％或99％以上)。
在本申请中，术语“第一多核苷酸”通常是指包含核酸片段I的多核苷酸。在本申请中，所述第一多核苷酸还可以在5’端和/或3’端存在内切酶(例如，限制性内切核酸酶)的识别位点。例如，所述第一多核苷酸可以以5’至3’方向包含结构R1-核酸片段I-R2，其中所述R1、R2可以为限制性内切核酸酶的识别位点。例如，经识别所述第一多核苷酸中的内切酶 识别位点的内切酶(例如，识别R1和R2的限制性内切核酸酶，例如SfiI或BsmBI)酶切处理后，经酶切处理的所述第一多核苷酸可包含所述核酸片段I。
在本申请中，术语“第一载体多核苷酸”通常是指包含载体片段I的多核苷酸。在本申请中，所述第一载体多核苷酸还可以在5’端和/或3’端存在内切酶(例如，限制性内切核酸酶)的识别位点。例如，所述第一载体多核苷酸可以以5’至3’方向包含结构R2-载体片段I-R3，其中所述R2、R3可以为限制性内切核酸酶的识别位点。例如，经识别所述第一载体多核苷酸中的内切酶识别位点的内切酶(例如，识别R2和R3的限制性内切核酸酶，例如SfiI或BsmBI)酶切处理后，经酶切处理的所述第一载体多核苷酸可包含所述载体片段I。
在本申请中，术语“第二多核苷酸”通常是指包含参比核酸片段II的多核苷酸。在本申请中，所述第二多核苷酸还可以在5’端和/或3’端存在内切酶(例如，限制性内切核酸酶)的识别位点。例如，所述第二多核苷酸可以以5’至3’方向包含结构R3-参比核酸片段II-R4，其中所述R3、R4可以为限制性内切核酸酶的识别位点。例如，经识别所述第二多核苷酸中的内切酶识别位点的内切酶(例如，识别R3和R4的限制性内切核酸酶，例如SfiI或BsmBI)酶切处理后，经酶切处理的所述第二多核苷酸可包含所述参比核酸片段II。
在本申请中，术语“第二载体多核苷酸”通常是指包含载体片段II的多核苷酸。在本申请中，所述第二载体多核苷酸还可以在5’端和/或3’端存在内切酶(例如，限制性内切核酸酶)的识别位点。例如，所述第二载体多核苷酸可以以5’至3’方向包含结构R4-载体片段II-R1，其中所述R4、R1可以为限制性内切核酸酶的识别位点。例如，经识别所述第二载体多核苷酸中的内切酶识别位点的内切酶(例如，识别R4和R1的限制性内切核酸酶，例如SfiI或BsmBI)酶切处理后，经酶切处理的所述第二载体多核苷酸可包含所述载体片段II。
在本申请中，术语“第三多核苷酸”通常是指包含核酸片段I’的多核苷酸。在本申请中，所述第三多核苷酸还可以在5’端和/或3’端存在内切酶(例如，限制性内切核酸酶)的识别位点。例如，所述第三多核苷酸可以以5’至3’方向包含结构R5-核酸片段I’-R6，其中所述R5、R6可以为限制性内切核酸酶的识别位点。例如，经识别所述第三多核苷酸中的内切酶识别位点的内切酶(例如，识别R5和R6的限制性内切核酸酶，例如SfiI或BsmBI)酶切处理后，经酶切处理的所述第三多核苷酸可包含所述核酸片段I’。
在本申请中，术语“第三载体多核苷酸”通常是指包含载体片段III的多核苷酸。在本申请中，所述第三载体多核苷酸还可以在5’端和/或3’端存在内切酶(例如，限制性内切核酸酶)的识别位点。例如，所述第三载体多核苷酸可以以5’至3’方向包含结构R6-载体片段III-R7，其中所述R6、R7可以为限制性内切核酸酶的识别位点。例如，经识别所述第三载 体多核苷酸中的内切酶识别位点的内切酶(例如，识别R6和R7的限制性内切核酸酶，例如SfiI或BsmBI)酶切处理后，经酶切处理的所述第三载体多核苷酸可包含所述载体片段III。
在本申请中，术语“第四多核苷酸”通常是指包含核酸片段II’的多核苷酸。在本申请中，所述第四多核苷酸还可以在5’端和/或3’端存在内切酶(例如，限制性内切核酸酶)的识别位点。例如，所述第四多核苷酸可以以5’至3’方向包含结构R7-核酸片段II’-R8，其中所述R7、R8可以为限制性内切核酸酶的识别位点。例如，经识别所述第四多核苷酸中的内切酶识别位点的内切酶(例如，识别R7和R8的限制性内切核酸酶，例如SfiI或BsmBI)酶切处理后，经酶切处理的所述第二多核苷酸可包含所述核酸片段II’。
在本申请中，术语“第四载体多核苷酸”通常是指包含载体片段IV的多核苷酸。在本申请中，所述第四载体多核苷酸还可以在5’端和/或3’端存在内切酶(例如，限制性内切核酸酶)的识别位点。例如，所述第四载体多核苷酸可以以5’至3’方向包含结构R8-载体片段IV-R5，其中所述R8、R5可以为限制性内切核酸酶的识别位点。例如，经识别所述第四载体多核苷酸中的内切酶识别位点的内切酶(例如，识别R8和R5的限制性内切核酸酶，例如SfiI或BsmBI)酶切处理后，经酶切处理的所述第四载体多核苷酸可包含所述载体片段IV。
在本申请中，术语“第五多核苷酸”通常是指包含参比核酸片段I的多核苷酸。在本申请中，所述第五多核苷酸还可以在5’端和/或3’端存在内切酶(例如，限制性内切核酸酶)的识别位点。例如，所述第五多核苷酸可以以5’至3’方向包含结构R9-参比核酸片段I-R10，其中所述R9、R10可以为限制性内切核酸酶的识别位点。例如，经识别所述第五多核苷酸中的内切酶识别位点的内切酶(例如，识别R9和R10的限制性内切核酸酶，例如SfiI或BsmBI)酶切处理后，经酶切处理的所述第五多核苷酸可包含所述参比核酸片段I。
在本申请中，术语“第五载体多核苷酸”通常是指包含载体片段V的多核苷酸。在本申请中，所述第五载体多核苷酸还可以在5’端和/或3’端存在内切酶(例如，限制性内切核酸酶)的识别位点。例如，所述第五载体多核苷酸可以以5’至3’方向包含结构R10-载体片段V-R11，其中所述R10、R11可以为限制性内切核酸酶的识别位点。例如，经识别所述第五载体多核苷酸中的内切酶识别位点的内切酶(例如，识别R10和R11的限制性内切核酸酶，例如SfiI或BsmBI)酶切处理后，经酶切处理的所述第五载体多核苷酸可包含所述载体片段V。
在本申请中，术语“第六多核苷酸”通常是指包含核酸片段II的多核苷酸。在本申请中，所述第六多核苷酸还可以在5’端和/或3’端存在内切酶(例如，限制性内切核酸酶)的识别位点。例如，所述第六多核苷酸可以以5’至3’方向包含结构R11-核酸片段II-R12，其中所述R11、R12可以为限制性内切核酸酶的识别位点。例如，经识别所述第六多核苷酸中的内切酶识别位点的内切酶(例如，识别R11和R12的限制性内切核酸酶，例如SfiI或BsmBI)酶切处理后，经酶切处理的所述第六多核苷酸可包含所述核酸片段II。
在本申请中，术语“第六载体多核苷酸”通常是指包含载体片段VI的多核苷酸。在本申请中，所述第六载体多核苷酸还可以在5’端和/或3’端存在内切酶(例如，限制性内切核酸酶)的识别位点。例如，所述第六载体多核苷酸可以以5’至3’方向包含结构R12-载体片段VI-R9，其中所述R12、R9可以为限制性内切核酸酶的识别位点。例如，经识别所述第六载体多核苷酸中的内切酶识别位点的内切酶(例如，识别R12和R9的限制性内切核酸酶，例如SfiI或BsmBI)酶切处理后，经酶切处理的所述第六载体多核苷酸可包含所述载体片段VI。
在本申请中，术语“切割后的第一多核苷酸”通常是指用限制性核酸内切酶处理第一多核苷酸得到的核酸分子。“切割后的第一多核苷酸”包含核酸片段I，以及两端的限制性核酸内切酶处理后得到的具有特定序列的末端。
在本申请中，术语“切割后的第一载体多核苷酸”通常是指用限制性核酸内切酶处理第一载体多核苷酸得到的核酸分子。“切割后的第一载体多核苷酸”包含载体片段I，以及两端的限制性核酸内切酶处理后得到的具有特定序列的末端。
在本申请中，术语“切割后的第二多核苷酸”通常是指用限制性核酸内切酶处理第二多核苷酸得到的核酸分子。“切割后的第二多核苷酸”包含参比核酸片段II，以及两端的限制性核酸内切酶处理后得到的具有特定序列的末端。
在本申请中，术语“切割后的第二载体多核苷酸”通常是指用限制性核酸内切酶处理第二载体多核苷酸得到的核酸分子。“切割后的第二载体多核苷酸”包含载体片段II，以及两端的限制性核酸内切酶处理后得到的具有特定序列的末端。
在本申请中，术语“切割后的第三多核苷酸”通常是指用限制性核酸内切酶处理第三多核苷酸得到的核酸分子。“切割后的第三多核苷酸”包含核酸片段I’，以及两端的限制性核酸内切酶处理后得到的具有特定序列的末端。
在本申请中，术语“切割后的第三载体多核苷酸”通常是指用限制性核酸内切酶处理第三载体多核苷酸得到的核酸分子。“切割后的第三载体多核苷酸”包含载体片段III，以及两端的限制性核酸内切酶处理后得到的具有特定序列的末端。
在本申请中，术语“切割后的第四多核苷酸”通常是指用限制性核酸内切酶处理第四多核苷酸得到的核酸分子。“切割后的第四多核苷酸”包含参比核酸片段II’，以及两端的限制性核酸内切酶处理后得到的具有特定序列的末端。
在本申请中，术语“切割后的第四载体多核苷酸”通常是指用限制性核酸内切酶处理第四载体多核苷酸得到的核酸分子。“切割后的第四载体多核苷酸”包含载体片段IV，以及两端的限制性核酸内切酶处理后得到的具有特定序列的末端。
在本申请中，术语“切割后的第五多核苷酸”通常是指用限制性核酸内切酶处理第五多核苷酸得到的核酸分子。“切割后的第五多核苷酸”包含参比核酸片段I，以及两端的限制性核酸内切酶处理后得到的具有特定序列的末端。
在本申请中，术语“切割后的第五载体多核苷酸”通常是指用限制性核酸内切酶处理第五载体多核苷酸得到的核酸分子。“切割后的第五载体多核苷酸”包含载体片段V，以及两端的限制性核酸内切酶处理后得到的具有特定序列的末端。
在本申请中，术语“切割后的第六多核苷酸”通常是指用限制性核酸内切酶处理第六多核苷酸得到的核酸分子。“切割后的第六多核苷酸”包含核酸片段II，以及两端的限制性核酸内切酶处理后得到的具有特定序列的末端。
在本申请中，术语“切割后的第六载体多核苷酸”通常是指用限制性核酸内切酶处理第六载体多核苷酸得到的核酸分子。“切割后的第六载体多核苷酸”包含载体片段VI，以及两端的限制性核酸内切酶处理后得到的具有特定序列的末端。
在本申请中，术语“第一待筛选载体”通常是指包含核酸片段I、参比核酸片段II、载体片段I和载体片段II的环形核酸分子。在某些实施方式中，所述“第一待筛选载体”由切割后的第一多核苷酸、切割后的第二多核苷酸、切割后的第一载体多核苷酸和切割后的第二载体多核苷酸定向连接而成。在某些情形中，“第一待筛选载体”能够表达形成抗原结合蛋白。在另一些情形中，“第一待筛选载体”不能表达形成抗原结合蛋白。当“第一待筛选载体”表达形成的抗原结合蛋白具有一种或多种以下性质时：能够结合参比抗原结合蛋白特异性结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上(例如，35％、40％、45％、50％、55％、60％、65％、70％、75％、80％、85％、90％、95％或99％以上)，所述“第一待筛选载体”可以被称为“第一置换载体”，且所述“第一待筛选载体” 中的核酸片段I可以被称为核酸片段I’。“第一待筛选载体库”包含一个或多个第一待筛选载体。
在本申请中，术语“第一置换载体”通常是指包含核酸片段I’、参比核酸片段II、载体片段I和载体片段II的环形核酸分子，“第一置换载体”可以表达形成抗原结合蛋白，且所述抗原结合蛋白具有一种或多种以下性质：能够结合参比抗原结合蛋白特异性结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上(例如，35％、40％、45％、50％、55％、60％、65％、70％、75％、80％、85％、90％、95％或99％以上)。“第一置换载体库”包含一个或多个“第一置换载体”，且不包含那些表达形成的抗原结合蛋白不具有一种或多种以下性质的第一待筛选载体：能够结合所述参比抗原结合蛋白特异性结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上(例如，35％、40％、45％、50％、55％、60％、65％、70％、75％、80％、85％、90％、95％或99％以上)。
在本申请中，术语“第二待筛选载体”通常是指包含核酸片段II、参比核酸片段I、载体片段V和载体片段VI的环形核酸分子。在某些实施方式中，所述“第二待筛选载体”由切割后的第五多核苷酸、切割后的第六多核苷酸、切割后的第五载体多核苷酸和切割后的第六载体多核苷酸定向连接而成。“第二待筛选载体”可以表达形成抗原结合蛋白。当“第二待筛选载体”表达形成的抗原结合蛋白具有以下性质时：能够结合所述参比抗原结合蛋白特异性结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上(例如，35％、40％、45％、50％、55％、60％、65％、70％、75％、80％、85％、90％、95％或99％以上，所述“第二待筛选载体”可以被称为“第二置换载体”，且所述“第二待筛选载体”中的核酸片段II可以被称为核酸片段II’。“第二待筛选载体库”包含一个或多个第二待筛选载体。
在本申请中，术语“第二置换载体”通常是指包含核酸片段II’、参比核酸片段I、载体片段V和载体片段VI的环形核酸分子，“第二置换载体”可以表达形成抗原结合蛋白，且所述抗原结合蛋白具有以下性质：能够结合参比抗原结合蛋白特异性结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上(例如，35％、40％、45％、50％、55％、60％、65％、70％、75％、80％、85％、90％、95％或99％以上)。在本申请中，所述“第二置换载体库”包含一个或多个“第二置换载体”，且不包含那些表达形成的抗原结合蛋白不具有以下性质的第二待筛选载体：能够结合所述参比抗原结合蛋白特异性结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以 上(例如，35％、40％、45％、50％、55％、60％、65％、70％、75％、80％、85％、90％、95％或99％以上)。
在本申请中，术语“双置换待筛选载体”通常是指包含核酸片段I’、核酸片段II’、载体片段I和载体片段II的环形核酸分子。所述“双置换待筛选载体”通常是由切割后的第一多核苷酸、所述切割后的第二多核苷酸、所述切割后的第一载体多核苷酸和所述切割后的第二载体多核苷酸定向连接而成。在某些情形中，“双置换待筛选载体”能够表达形成抗原结合蛋白。在另一些情形中，“双置换待筛选载体”不能表达形成抗原结合蛋白。如果双置换待筛选载体的表达产物具有以下性质：能够结合参比抗原结合蛋白特异性结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上(例如，35％以上、40％以上、45％以上、50％以上、55％以上、60％以上、65％以上、70％以上、75％以上、80％以上、85％以上、90％以上、95％以上、99％以上、1倍以上、1.5倍以上、2倍以上、2.5倍以上、3倍以上或更多)，则所述双置换待筛选载体可以被称为双置换载体。“双置换待筛选载体库”包含一个或多个“双置换待筛选载体”。
在本申请中，术语“切割”通常是指使限制性核酸内切酶和多核苷酸在使得能够切割的条件下接触。所述切割通常是指将核苷酸的糖类分子与相邻核苷酸分子的磷酸之间的键切断，例如，所述切割通常是指将两个核苷酸之间的磷酸二酯键切断。使用限制性核酸内切酶切割后，所述多核苷酸可以产生特定序列的末端。
在本申请中，术语“连接”通常是指将两个或者两个以上的多核苷酸分子连接在一起。例如，所述连接可以通过连接酶(例如，DNA连接酶)实现。例如，使一个多核苷酸的3’端与另一个多核苷酸的5’端连接，从而形成一个完整的多核苷酸分子。“定向连接”通常是指使两个或者两个以上的多核苷酸分子按照一定的顺序连接在一起。
在本申请中，术语“导入”通常是指将外源多核苷酸转移或导入细胞中的过程。所述细胞可以为宿主细胞。所述导入的细胞包括对象的初级细胞及其后代。所述细胞可以为原核细胞，例如，可以为细菌细胞。所述细胞可以为真核细胞，例如，可以为哺乳动物细胞或酵母细胞。
在本申请中，术语“连接子”通常是指能够将两种以上多核苷酸分子或其片段相连接的试剂。所述连接子可以为多核苷酸或其片段。在本申请中，所述连接子可以具备不同的长度。例如，所述连接子的长度可以为40bp以上、50bp以上、60bp以上、70bp以上、80bp以上、90bp以上、100bp以上、150bp以上、200bp以上或更长。在某些情形中，所述连接子包含信号肽，术语“信号肽pelB”通常是指果胶酶裂解酶的信号肽，例如，当抗原结合蛋白是 Fab的情况。所述信号肽pelB通常用于原核表达系统。例如，所述信号肽pelB在GenBank中的登录号可以为ABS75961.1。在某些情形中，所述连接子不包含信号肽，例如，当抗原结合蛋白是scFv的情况。在某些情况下，所述第一多核苷酸可以包括编码VH的核酸分子，且所述第二多核苷酸可以包括编码VL的核酸分子；在某些情况下，所述第一多核苷酸可以包括编码VL的核酸分子，且所述第二多核苷酸可以包括编码VH的核酸分子。
在本申请中，术语“轻链或其片段”通常是指具备与同一或类似抗体的重链相结合的能力的氨基酸片段。在本申请中，所述轻链或其片段可包含轻链可变区(VL)和轻链恒定区(CL)。所述轻链恒定区可以分为κ型和λ型。所述轻链还包括具有与κ恒定区(C-κ)相连的λ可变区(V-λ)或与λ恒定区(C-λ)相连的κ可变区(V-κ)的轻链。
在本申请中，术语“重链或其片段”通常是指具备与同一或类似抗体的轻链相结合的能力的氨基酸片段。在本申请中，所述重链或其片段可具备与同一或类似抗体的轻链相结合的能力。在本申请中，所述重链或重链片段可包含重链可变区(VH)和重链恒定区(CH)。所述重链恒定区可包含CH1结构域、铰链区、CH2结构域和CH3结构域。在IgE、IgM和IgY的情况下，所述重链恒定区可包含CH4结构域但是不具有铰链区。在本申请中，所述“重链恒定区”可以为CH1、铰链区、CH2、CH3、CH4结构域或其任何组合。
在本申请中，术语“限制性内切核酸酶”通常是指一种将双股DNA切开的酶。所述限制性内切核酸酶可以产生具有突出单股DNA的黏性末端，从而可以与DNA连接酶黏合。在本申请中，所述限制性内切核酸酶可以具备识别和限制性切割的作用。例如，所述限制性内切核酸酶的切割位点距离其识别位点存在一定的距离。例如，所述限制性内切核酸酶可以选自SfiI，BsmBI和Esp3I。
在本申请中，术语“多核苷酸”通常是指核苷酸，即连接在一起的至少两个核苷酸。所述多核苷酸可以是任何长度的聚合物，包括例如200、300、500、1000、2000、3000、5000、7000、10,000、100,000等。所述多核苷酸可以含有磷酸二酯键。
在本申请中，术语“包含”通常是指包括明确指定的特征，但不排除其他要素。
在本申请中，术语“约”通常是指在指定数值以上或以下0.5％-10％的范围内变动，例如在指定数值以上或以下0.5％、1％、1.5％、2％、2.5％、3％、3.5％、4％、4.5％、5％、5.5％、6％、6.5％、7％、7.5％、8％、8.5％、9％、9.5％、或10％的范围内变动。
发明详述
本申请将链置换技术和抗体展示技术(例如，噬菌体展示技术和哺乳动物细胞展示技术)结合，提供了一种选择功能性抗原结合蛋白的方法。
第一次置换
在本申请中，所述方法包括使用参比抗原结合蛋白的抗体重链或其片段(或抗体轻链或其片段)，与多种抗体轻链或其片段(或抗体重链或其片段)，构建包含第一待筛选载体的待筛选库。所述第一待筛选载体可以是噬菌体展示载体或细胞展示载体，或根据实际情况可选择的其他任何展示载体。具体来说，所述方法包括a)提供第一多核苷酸，所述第一多核苷酸以5’至3’方向包含R1-核酸片段I-R2，所述核酸片段I能够编码抗原结合片段I；b)提供第二多核苷酸，所述第二多核苷酸以5’至3’方向包含R3-参比核酸片段II-R4，所述参比核酸片段II能够编码参比抗原结合片段II，所述参比抗原结合片段II能够与由参比核酸片段I编码的参比抗原结合片段I形成参比抗原结合蛋白；c)提供第一载体多核苷酸，所述第一载体多核苷酸以5’至3’方向包含R2-载体片段I-R3；d)提供第二载体多核苷酸，所述第二载体多核苷酸以5’至3’方向包含R4-载体片段II-R1；e)用限制性核酸内切酶切割所述第一多核苷酸、所述第二多核苷酸、所述第一载体多核苷酸和所述第二载体多核苷酸，得到切割后的第一多核苷酸、切割后的第二多核苷酸、切割后的第一载体多核苷酸和切割后的第二载体多核苷酸；f)混合所述切割后的第一多核苷酸、所述切割后的第二多核苷酸、所述切割后的第一载体多核苷酸和所述切割后的第二载体多核苷酸，从而使得其能够定向连接而环化形成第一待筛选载体。所述第一待筛选载体的结构可参见图1。所述方法还包括使所述待筛选载体表达，通过与参比抗原结合蛋白(或其他阳性对照抗体)的比较，选择具有以下性质的抗原结合蛋白作为功能性抗原结合蛋白：能够结合所述参比结合蛋白能够结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上。
在本申请中，所述核酸片段I可编码抗体轻链或其片段，所述参比核酸片段II可编码参比抗原结合蛋白的重链或其片段，所述载体片段I可包含连接肽，所述载体片段II可源自噬菌体展示载体(例如pComb3x载体)。在某些情形中，所述核酸片段I编码抗体轻链，所述连接肽包含编码信号肽pelB或其片段的核酸序列。在某些情形中，所述核酸片段I编码抗体轻链可变区。所述R1可包含SEQ ID NO:1所示的核苷酸序列，所述R2可包含SEQ ID NO:2所示的核苷酸序列，所述R3可包含SEQ ID NO:3所示的核苷酸序列，所述R4可包含SEQ ID NO:4所示的核苷酸序列。
在本申请中，所述核酸片段I可编码抗体轻链或其片段，所述参比核酸片段II可编码参比抗原结合蛋白的重链或其片段，所述载体片段I和/或所述载体片段II可源自哺乳动物细胞表达载体(例如pDGB4载体)。所述R1可包含SEQ ID NO:7所示的核苷酸序列，所述R2可包含SEQ ID NO:8所示的核苷酸序列，所述R3可包含SEQ ID NO:5所示的核苷酸序列，所述R4可包含SEQ ID NO:6所示的核苷酸序列。
在本申请中，所述核酸片段I可编码抗体重链或其片段，所述参比核酸片段II可编码参比抗原结合蛋白的轻链或其片段，所述载体片段II可包含连接肽，所述载体片段I可源自噬菌体展示载体(例如pComb3x载体)。在某些情形中，所述参比核酸片段II编码抗体轻链，所述连接肽包含编码信号肽pelB或其片段的核酸序列。在某些情形中，所述参比核酸片段II编码抗体轻链可变区。所述R1可包含SEQ ID NO:3所示的核苷酸序列，所述R2可包含SEQ ID NO:4所示的核苷酸序列，所述R3可包含SEQ ID NO:1所示的核苷酸序列，所述R4可包含SEQ ID NO:2所示的核苷酸序列。
在本申请中，所述核酸片段I可编码抗体重链或其片段，所述参比核酸片段II可编码参比抗原结合蛋白的轻链或其片段，所述载体片段I和/或所述载体片段II可源自哺乳动物细胞表达载体(例如pDGB4载体)。所述R1可包含SEQ ID NO:5所示的核苷酸序列，所述R2可包含SEQ ID NO:6所示的核苷酸序列，所述R3可包含SEQ ID NO:7所示的核苷酸序列，所述R4可包含SEQ ID NO:8所示的核苷酸序列。
能够表达功能性抗原结合蛋白的第一待筛选载体称为第一置换载体，相应地，能够表达功能性抗原结合蛋白的第一待筛选载体的核酸片段I称为第一置换载体的核酸片段I’。
第二次置换
本申请的方法还可以包括：获得核酸片段I’以后，与核酸片段II’构建双置换待筛选载体。所述核酸片段II’可以通过本领域任意方法获得，例如，使用参比抗原结合蛋白的参比抗原结合片段置换得到，只要其满足以下条件即可：能够编码抗原结合蛋白II’，且所述抗原结合片段II’能够与所述参比抗原结合片段I形成具有以下性质的抗原结合蛋白：能够结合参比抗原结合能够结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上。
在某些情形中，通过构建第二待筛选载体获得所述核酸片段II’。本申请所述的方法进一步包括a)提供第五多核苷酸，所述第五多核苷酸以5’至3’方向包含R9-参比核酸片段I-R10；b)提供第六多核苷酸，所述第六多核苷酸以5’至3’方向包含R11-核酸片段II-R12；c)提供第五载体多核苷酸，所述第五载体多核苷酸以5’至3’方向包含R10-载体片段 V-R11；d)提供第六载体多核苷酸，所述第六载体多核苷酸以5’至3’方向包含R12-载体片段VI-R9；e)用限制性核酸内切酶切割所述第五多核苷酸、所述第六多核苷酸、所述第五载体多核苷酸和所述第六载体多核苷酸，得到切割后的第五多核苷酸、切割后的第六多核苷酸、切割后的第五载体多核苷酸和切割后的第六载体多核苷酸；f)混合所述切割后的第五多核苷酸、所述切割后的第六多核苷酸、所述切割后的第五载体多核苷酸和所述切割后的第六载体多核苷酸，从而使得其能够定向连接而环化形成第二待筛选载体。所述第二待筛选载体的结构可参见图3。所述方法还包括使所述待筛选载体表达，通过与参比抗原结合蛋白(或其他阳性对照抗体)的比较，选择具有以下性质的抗原结合蛋白作为功能性抗原结合蛋白：能够结合所述参比结合蛋白能够结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上。
所述核酸片段II编码的是抗体轻链或其片段还是抗体重链或其片段，取决于核酸片段I的类型。只要核酸片段II编码的多肽能与核酸片段I编码的多肽两者之一为抗体轻链或其片段，另一为抗体重链或其片段即可。
在本申请中，所述参比核酸片段I可编码参比抗原结合蛋白的抗体轻链或其片段，所述核酸片段II可编码抗体重链或其片段，所述载体片段V可包含连接肽，所述载体片段VI可源自噬菌体展示载体(例如pComb3x载体)。在某些情形中，所述参比核酸片段I编码抗体轻链，所述连接肽包含编码信号肽pelB或其片段的核酸序列。在某些情形中，所述参比核酸片段I编码抗体轻链可变区。所述R9可包含SEQ ID NO:1所示的核苷酸序列，所述R10可包含SEQ ID NO:2所示的核苷酸序列，所述R11可包含SEQ ID NO:3所示的核苷酸序列，所述R12可包含SEQ ID NO:4所示的核苷酸序列。
在本申请中，所述参比核酸片段I可编码参比抗原结合蛋白的抗体轻链或其片段，所述核酸片段II可编码重链或其片段，所述载体片段V和/或所述载体片段VI可源自哺乳动物细胞表达载体(例如pDGB4载体)。所述R9可包含SEQ ID NO:7所示的核苷酸序列，所述R10可包含SEQ ID NO:8所示的核苷酸序列，所述R11可包含SEQ ID NO:5所示的核苷酸序列，所述R12可包含SEQ ID NO:6所示的核苷酸序列。
在本申请中，所述参比核酸片段I可编码参比抗原结合蛋白的抗体重链或其片段，所述核酸片段II可编码抗原结合蛋白的轻链或其片段，所述载体片段VI可包含连接肽，所述载体片段V可源自噬菌体展示载体(例如pComb3x载体)。在某些情形中，所述核酸片段II编码抗体轻链，所述连接肽包含编码信号肽pelB或其片段的核酸序列。在某些情形中，所述核酸片段II编码抗体轻链可变区。所述R9可包含SEQ ID NO:3所示的核苷酸序列，所 述R10可包含SEQ ID NO:4所示的核苷酸序列，所述R11可包含SEQ ID NO:1所示的核苷酸序列，所述R12可包含SEQ ID NO:2所示的核苷酸序列。
在本申请中，所述参比核酸片段I可编码抗体重链或其片段，所述核酸片段II可编码参比抗原结合蛋白的轻链或其片段，所述载体片段V和/或所述载体片段VI可源自哺乳动物细胞表达载体(例如pDGB4载体)。所述R9可包含SEQ ID NO:5所示的核苷酸序列，所述R10可包含SEQ ID NO:6所示的核苷酸序列，所述R11可包含SEQ ID NO:7所示的核苷酸序列，所述R12可包含SEQ ID NO:8所示的核苷酸序列。
双置换
本申请所述的方法进一步包括：获得核酸片段I’和核酸片段II’，且核酸片段I’编码的多肽能与核酸片段II’编码的多肽两者之一为抗体轻链或其片段，另一为抗体重链或其片段；b)提供第三多核苷酸，所述第三多核苷酸以5’至3’方向包含R5-核酸片段I’-R6；c)提供第四多核苷酸，所述第四多核苷酸以5’至3’方向包含R7-核酸片段II’-R8，所述核酸片段II’能够编码抗原结合蛋白II’，且所述抗原结合片段II’能够与所述参比抗原结合片段I形成具有以下性质的抗原结合蛋白：能够结合参比抗原结合能够结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上；d)提供第三载体多核苷酸，所述第三载体多核苷酸以5’至3’方向包含R6-载体片段III-R7；e)提供第四载体多核苷酸，所述第四载体多核苷酸以5’至3’方向包含R8-载体片段IV-R5；f)用限制性核酸内切酶切割所述第三多核苷酸、所述第四多核苷酸、所述第三载体多核苷酸和所述第四载体多核苷酸，得到切割后的第三多核苷酸、切割后的第四多核苷酸、切割后的第三载体多核苷酸和切割后的第四载体多核苷酸；g)混合所述切割后的第三多核苷酸、所述切割后的第四多核苷酸、所述切割后的第三载体多核苷酸和所述切割后的第四载体多核苷酸，从而使得其能够定向连接而环化形成双置换待筛选载体。所述双置换待筛选载体的结构可参见图2。所述方法还包括使所述待筛选载体表达，通过与参比抗原结合蛋白(或其他阳性对照抗体)的比较，选择具有以下性质的抗原结合蛋白作为功能性抗原结合蛋白：能够结合所述参比结合蛋白能够结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上。
在本申请中，所述核酸片段I’可编码参比抗原结合蛋白的抗体轻链或其片段，所述核酸片段II’可编码抗体重链或其片段，所述载体片段III可包含连接肽，所述载体片段IV可源自噬菌体展示载体(例如pComb3x载体)。在某些情形中，所述核酸片段I’编码抗体轻链，所述连接肽包含编码信号肽pelB或其片段的核酸序列。在某些情形中，所述核酸片段I’编码抗体轻链可变区。所述R5可包含SEQ ID NO:1所示的核苷酸序列，所述R6可包含 SEQ ID NO:2所示的核苷酸序列，所述R7可包含SEQ ID NO:3所示的核苷酸序列，所述R8可包含SEQ ID NO:4所示的核苷酸序列。
在本申请中，所述核酸片段I’可编码参比抗原结合蛋白的抗体轻链或其片段，所述核酸片段II’可编码重链或其片段，所述载体片段III和/或所述载体片段IV可源自哺乳动物细胞表达载体(例如pDGB4载体)。所述R5可包含SEQ ID NO:7所示的核苷酸序列，所述R6可包含SEQ ID NO:8所示的核苷酸序列，所述R7可包含SEQ ID NO:5所示的核苷酸序列，所述R8可包含SEQ ID NO:6所示的核苷酸序列。
在本申请中，所述核酸片段I’可编码参比抗原结合蛋白的抗体重链或其片段，所述核酸片段II’可编码抗原结合蛋白的轻链或其片段，所述载体片段IV可包含连接肽，所述载体片段III可源自噬菌体展示载体(例如pComb3x载体)。在某些情形中，所述核酸片段II’编码抗体轻链，所述连接肽包含编码信号肽pelB或其片段的核酸序列。在某些情形中，所述核酸片段II’编码抗体轻链可变区。所述R5可包含SEQ ID NO:3所示的核苷酸序列，所述R6可包含SEQ ID NO:4所示的核苷酸序列，所述R7可包含SEQ ID NO:1所示的核苷酸序列，所述R8可包含SEQ ID NO:2所示的核苷酸序列。
在本申请中，所述核酸片段I’可编码抗体重链或其片段，所述核酸片段II’可编码参比抗原结合蛋白的轻链或其片段，所述载体片段III和/或所述载体片段IV可源自哺乳动物细胞表达载体(例如pDGB4载体)。所述R5可包含SEQ ID NO:5所示的核苷酸序列，所述R6可包含SEQ ID NO:6所示的核苷酸序列，所述R7可包含SEQ ID NO:7所示的核苷酸序列，所述R8可包含SEQ ID NO:8所示的核苷酸序列。
本申请所述的方法可用于同时选择针对多个靶点、一个靶点的多个结合位点的功能性抗原结合蛋白。在应用本申请的方法时，在构建第一待筛选载体和/或第二待筛选载体时，可以同时使用针对同一抗原而结合不同表位的多种参比抗原结合蛋白，获得包含多种参比抗原结合片段的待筛选载体，用以获得编码针对同一个抗原但结合不同表位的多种功能性抗原结合蛋白的片段(核酸片段I’或核酸片段II’)。在应用本申请的方法时，也可以同时使用针对不同抗原的多种参比抗原结合蛋白，获得包含多种参比抗原结合片段的待筛选载体，用以获得编码针对不同抗原的多种功能性抗原结合蛋白的片段(核酸片段I’或核酸片段II’)。
例如，所述第一待筛选载体库中可包含含有多种参比核酸片段II的第一待筛选载体，所述参比核酸片段I编码结合同一抗原的2种、3种、4种或更多种参比抗原结合蛋白的片段。例如，所述第二待筛选载体库中可包含含有多种参比核酸片段I的第二待筛选载体，所 述参比核酸片段I编码结合同一抗原的2种、3种、4种或更多种参比抗原结合蛋白的片段。
例如，所述第一待筛选载体库中可包含含有多种参比核酸片段II的第一待筛选载体，所述参比核酸片段II编码结合多种(例如，2种、3种、4种、5种、6种、7种、8种、9种、10种或更多种)抗原的不同的参比抗原结合蛋白的片段。例如，所述第二待筛选载体库中可包含含有多种参比核酸片段I的第二待筛选载体，所述参比核酸片段I编码结合多种(例如，2种、3种、4种、5种、6种、7种、8种、9种、10种或更多种)抗原的不同的参比抗原结合蛋白的片段。
因此，在一种或多种双置换待筛选载体的双置换待筛选载体库中，可包含针对多种(例如，2种、3种、4种、5种、6种、7种、8种、9种、10种或更多种)抗原的更多种例如，2种、3种、4种、5种、6种、7种、8种、9种、10种、11种、12种、13种、14种、15种、16种、17种或更多种)抗原结合蛋白。
在本申请中，关于构建用于噬菌体表达的待筛选载体的部分，可参考PCT国际申请PCT/CN2020/085706。
在本申请中，所述连接子可包含编码信号肽pelB的片段的核酸序列，其余编码信号肽pelB的片段的核酸序列还可以位于所述多核苷酸的识别位点中。例如，所述编码信号肽pelB的片段的核酸序列的3’端的核苷酸可以位于所述酶切位点中。例如，当两个切割后的多核苷酸连接时，一多核苷酸中包含的编码信号肽pelB的片段的核酸序列可以与另一多核苷酸中包含的编码信号肽pelB的片段的核酸序列相连接，从而形成编码完整的信号肽pelB的核酸序列。
在本申请中，所述连接子的长度可以为约50至约200个碱基。例如，所述连接子的长度可以为约50至约200个碱基、约50至约180个碱基、约50至约160个碱基、约50至约140个碱基、约50至约120个碱基、约50至约100个碱基、约50至约90个碱基、约50至约80个碱基、约50至约75个碱基、约50至约70个碱基、约50至约60个碱基。
在本申请中，所述R1、R2、R3、R4、R5、R6、R7、R8、R9、R10、R11和R12中的任一项经限制性内切核酸酶切割后产生的末端可以为非回文序列。
在选择内切核酸酶识别位点时(例如，R1、R2、R3、R4、R5、R6、R7、R8、R9、R10、R11和R12时)，可选择核酸片段(例如，核酸片段I、核酸片段II、核酸片段I’、核酸片段II’、参比核酸片段I、参比核酸片段II’)中基本上不包含的序列以尽量保持其编码的抗原结合片段的功能区(例如，轻链可变区或重链可变区)的完整性，防止酶切时破坏 (例如，降解)抗体基因库。此外，所述核酸酶识别位点经限制性内切核酸酶切割后形成的末端可以是非回文序列，以防止其自我连接，进而实现减低非目的连接。此外，所述内切核酸酶识别位点的选择可使得多个片段的定向连接成为可能，以提高连接效率。
在本申请中，所述R1、R2、R3、R4、R5、R6、R7、R8、R9、R10、R11和R12中的两项或更多项(例如，2项、3项、4项、5项、6项、7项、8项、9项、10项、11项或12项)能够被相同的限制性内切核酸酶识别及切割。
在本申请中，所述限制性内切核酸酶可以选自SfiI，BsmBI和Esp3I。在本申请中，所述BsmBI和Esp3I可以为同工酶，其可以识别相同的限制性内切核酸酶的识别位点。
例如，SfiI可以识别由13个碱基构成的序列(5’至3’)GGCCNNNN/NGGCC(SEQ ID NO:9)，其经过酶切后可形成3’端的突出序列(overhang，例如包含3个碱基的单链序列)，其中N可以代表GATC四种碱基中的任何一种。因此，有64种不同的序列均能够被SfiI识别。
例如，BsmBI和Esp3I可以识别由12个碱基构成的序列(5’至3’)CGTCTCN/NNNNN(SEQ ID NO:10)，其经过酶切后可形成5’端的突出序列(overhang，例如包含4个碱基的单链序列)，其中N可以代表GATC四种碱基中的任何一种。因此，有264种不同的序列均能够被BsmBI和Esp3I识别。
在本申请中，为了构建本申请的载体，可以对所述噬菌体展示载体或哺乳动物细胞展示载体(例如，pDGB4和/或pComb3x载体)进行工程化/修饰。例如，可以通过定点突变去除所述载体中的一个或多个内切核酸酶识别位点。在某些情形中，也可以通过定点突变在所述载体中增加一个或多个内切核酸酶识别位点。
例如，可对所述pComb3x载体进行改造以适合用于本申请的目的。例如，所述pComb3x载体可包含一个位于5’端的SfiI识别位点以及一个位于3’端的SfiI识别位点，在所述改造过程中，可通过定点突变去除所述pComb3x载体中3’端的SfiI识别位点。在某些情形中，所述定点突变可不影响所述载体中蛋白(例如，抗体重链片段和/或抗体轻链片段)的框内表达。例如，所述突变可以为无义突变，例如仅改变碱基序列但不改变氨基酸序列的突变。
在某些情形中，当所述第一待筛选载体、第二待筛选载体和/或所述待筛选双置换载体使用哺乳动物细胞表达时，所述载体片段(例如载体片段I、载体片段II、载体片段III、载体片段IV、载体片段V和载体片段VI)可以来自任何一个能够表达目的基因的载体。例如，所述载体片段可以是来自展示载体pDGB4的片段(关于pDGB4请参见Ivan Zhou,et  al.,“Four-way ligation for construction of a mammalian cell-based fμLl-length antibody display library”,Acta Biochim Biophys Sin 2011,43:232–238)。
本申请的载体片段(例如，例如载体片段I、载体片段II、载体片段III、载体片段IV、载体片段V和载体片段VI)可包含具有特定功能的核苷酸序列，包括但不限于，启动子、增强子、信号肽、筛选标记(例如，可包括酶的识别位点、抗性基因、报告基因、筛选基因)，本领域技术人员可根据所期望功能在载体片段中调整(插入/替换和/或删除等上述具有特定功能的核苷酸序列)。在某些情况下，所述的载体片段可以在不同的情况下被调整而得到不同的核苷酸序列。
在本申请中，所述载体可包含或编码一个或多个合适的标记物(例如，用于纯化/识别/筛选的标记物)，所述标记物可以为，例如His tag，Flag Tag，荧光蛋白，选择性抗生素，和/或亲和素等。
可以根据要表达的抗原结合片段的长度或性质、酶切位点的长度或性质分别选择所需长度或种类的载体片段(例如，载体片段I、载体片段II、载体片段III、载体片段IV、载体片段V和/或载体片段VI)。
在本申请中，可以由样品材料获得所述核酸片段I和所述核酸片段II。在本申请中，所述样品材料可以包括源自外周血淋巴细胞样品的材料。在本申请中，所述外周血淋巴细胞可以为人外周血淋巴细胞。在本申请中，所述样品材料也可以源自其他任意的组织和/或细胞，并不限于所述外周血淋巴细胞样品。
例如，可以通过现有技术中已经构建的抗体轻链或其片段库或已经构建的抗体重链或其片段库获得所述核酸片段I和所述核酸片段II。所述方法包括在一种或多种抗体重链或其片段，或一种或多种抗体轻链或其片段的两端加上本申请所述的酶切位点。
在本申请中，可以使用多种方法检测所述的第一待筛选载体、第二待筛选载体和/或所述双置换待筛选载体的表达产物与所述靶标的结合能力。比较待筛选载体的表达产物和参比抗原结合蛋白或其他阳性对照的结合能力可以通过定量或不定量的方法比较。
在一个方面，例如可通过已知方法诸如酶联免疫吸附测定(ELISA)、免疫印迹(例如，蛋白质印迹)、流式细胞术(例如，FACS)、免疫组织化学、免疫荧光等来测试本申请抗原结合蛋白结合靶标的活性。在某些情形中，结合亲和力可通过表面等离子共振法(SPR)、酶联免疫法(ELISA)、结合抗原沉淀法、平衡透析法、生物膜干涉(BLI)测定。在某些情形中，PD-1抗原结合蛋白对PD-1的结合亲和力和KD值可通过生物膜干涉(BLI)测定。例如，可使用ELISA法测定。例如，在容许所述抗原结合蛋白和/或所述参 比抗原结合蛋白结合所述靶标的条件下，使所述的第一待筛选载体、第二待筛选载体和/或所述待筛选双置换载体的表达产物和/或所述参比抗原结合蛋白与所述靶标(例如，抗原)接触，检测在所述的第一待筛选载体、第二待筛选载体和/或所述待筛选双置换载体的表达产物与所述靶标之间是否形成复合物，和检测所述参比抗原结合蛋白与所述靶标之间是否形成复合物。
对于定量方法，与所述靶标结合能力可以包括结合靶标的EC 50值、结合靶标的KD值、与靶标结合形成的复合物的OD值和/或与靶标结合形成的复合物的吸光度。当所述的第一待筛选载体、第二待筛选载体和/或所述待筛选双置换载体的表达产物结合靶标的EC 50值、结合靶标的KD值、与靶标结合形成的复合物的OD值和/或与靶标结合形成的复合物的吸光度是所述参比抗体结合靶标的EC 50值、结合靶标的KD值、与靶标结合形成的复合物的OD值和/或与靶标结合形成的复合物的吸光度的30％以上(例如，35％、40％、45％、50％、55％、60％、65％、70％、75％、80％、85％、90％、95％、99％、100％、110％或120％以上)时，可以认为所述表达产物可以特异性结合所述靶标。或者，当所述的第一待筛选载体、第二待筛选载体和/或所述待筛选双置换载体的表达产物结合靶标的EC 50值、结合靶标的KD值、与靶标结合形成的复合物的OD值和/或与靶标结合形成的复合物的吸光度时是不存在所述的第一待筛选载体、第二待筛选载体、所述待筛选双置换载体的表达产物和/或所述参比抗原结合蛋白的阴性对照的2倍以上(例如，2.5倍、3倍、3.5倍以上)时，也可以认为所述表达产物可以特异性结合所述靶标。
另一方面，本申请提供了一种制备所述功能性抗原结合蛋白的方法，其包括使用所述的第一待筛选载体、第二待筛选载体和/或所述待筛选双置换载体。
另一方面，本申请提供了通过本申请所述的方法得到的功能性抗原结合蛋白。
不欲被任何理论所限，下文中的实施例仅仅是为了阐释本申请所述方法和本申请所述方法制得的功能性抗原结合蛋白等，而不用于限制本申请发明的范围。
实施例
实施例1制备携带16个参比抗体Fab噬菌体展示载体的Tg1细菌
1.1合成16个参比抗体的全长轻链和重链可变区基因：
通过文献搜索得到以下16个参比抗体的全长轻链和重链可变区的氨基酸序列：
Secukinumab，Selicrelumab，APX-005M，Tafasitamab，Ublituximab，Epratuzumab， Relatlimab，Leramilimab，Coblimab，Tiraglumab，Vibostolimab，Etigilimab，Amatuximab，TRX-518，Bleselumab，Iscalimab。
例如，通过文献搜索得到Selicrelumab全长轻链和全长重链的氨基酸序列(参见WO2018220100中的相关序列信息)。其中，Selicrelumab全长轻链的氨基酸序列如SEQ ID NO.11所示，Selicrelumab全长重链的氨基酸序列如SEQ ID NO.12所示。
将Selicrelumab全长轻链和重链可变区的氨基酸序列转换为可在大肠杆菌表达的碱基序列，在序列的两端加上与噬菌体展示载体相匹配的含有适当酶切序列和(或者)信号肽序列的碱基序列，合成基因，插入pUC57载体(金唯智生物科技有限公司合成)。
其中，合成的含全长轻链的核苷酸序列如SEQ ID NO.13所示，合成的含重链可变区的核苷酸序列如SEQ ID NO.14所示。
将16个参比抗体的全长轻链和重链可变区的氨基酸序列转换为可在大肠杆菌表达的碱基序列，在序列的两端加上与噬菌体展示载体相匹配的含有适当酶切序列和(或者)信号肽序列的碱基序列，合成基因，插入pUC57载体(金唯智生物科技有限公司)。
1.2构建16个参比抗体Fab噬菌体展示载体
用SfiI酶切含有合成的16个含全长轻链碱基序列的pUC 57载体，得到16个全长轻链片段，此片段即为图1的第一多核苷酸。
用SfiI+Esp3I双酶切含有合成的16个重链可变区碱基序列的pUC 57载体，得到16个重链可变区片段，此片段即为图1的第二多核苷酸。
将得到的16个全长轻链片段(即本申请图1的第一多核苷酸)，16个重链可变区片段(即本申请图1的第二多核苷酸)，按参比抗体对应的轻链片段，重链可变区片段与图1标示的第一载体多核苷酸，第二载体多核苷酸做16个4片段连接，测序分析克隆的碱基序列，得到16个阳性参比抗体Fab的噬菌体展示载体。第一载体多核苷酸和第二载体多核苷酸的描述和制备参见建库专利申请WO2020216191A1中的相关步骤。
例如，将得到的Selicrelumab全长轻链片段(第一多核苷酸)，Selicrelumab重链可变区片段(第二多核苷酸)与图1标示的第一载体多核苷酸，第二载体多核苷酸做4片段连接，测序分析克隆的碱基序列，得到阳性对标抗体Selicrelumab-Fab的噬菌体展示载体。第一载体多核苷酸和第二载体多核苷酸的描述和制备参见WO2020216191A1中的相关步骤。
具体而言，上述第一载体多核苷酸为WO2020216191A1实施例1.6记载的：以连接子组件质粒或实施例1.4.4中的连接子存储载体为模板，用连接子的正向引物(WO2020216191A1的SEQ ID NO:79)和连接子的反向引物(WO2020216191A1的SEQ ID NO:80)扩增含有 连接子的0.8kb的片段，然后用限制性内切核酸酶R3和R4酶切该0.8kb的PCR产物，经凝胶电泳纯化回收(利用小片段凝胶回收试剂盒，购自莱枫生物，Cat#DK402)得到72pb的连接子片段；
上述第二载体多核苷酸为WO2020216191A1实施例1.8记载的：利用限制性内切核酸酶R7和限制性内切核酸酶R8酶切实施例1.7制备的展示载体DDB-R1R2R5R6，获得3.6kb展示载体片段。
1.3制备携带16个参比抗体Fab噬菌体展示载体的TG1细菌
将16个参比抗体Fab的噬菌体展示载体导入TG1电感菌(Lucigen，Cat#：60502)，得到携带每一个参比抗体Fab噬菌体展示载体的TG1细菌。
例如，将阳性对标抗体Selicrelumab-Fab的噬菌体展示载体导入TG1电感菌，得到携带对标抗体Selicrelumab-Fab噬菌体展示载体的TG1细菌。
实施例2构建多参比抗体轻链置换基因库、细菌库和噬菌体库
1.用SfiI酶切全人源Kappa轻链和Lambda轻链亚库，制备Kappa轻链库和Lambda轻链库插入片段。
2.将得到的Kappa轻链库和Lambda轻链库插入片段(第一多核苷酸)，16个参比抗体重链可变区片段(第二多核苷酸)与图1标示的第一载体多核苷酸，第二载体多核苷酸(参见建库专利)做4片段连接，构建轻链置换库。4个片段以1:1:1:1的分子数等比例混合，总量2345ng，20度连接过夜(15小时)。
3.纯化连接产物，得到1062ng轻链置换库连接产物(基因库)。
4.转化3支TG1电感菌，菌液总量6000μl，37度/250rpm培养60分钟后，取10μl菌液做连接转化效率滴定。做8次10倍稀释，每个稀释度取5μl铺皿，32度培养过夜。
5.其余菌液，用220ml 2YT-Amp-2％glucose培养液稀释，37度250rpm培养3小时，测OD 600＝0.6(细菌库)。
6.取50ml第7步的细菌库菌液，转移到150ml摇瓶，37度250rpm继续培养4个小时，离心收菌，以4ml 2TY-Amp-7％DMSO悬起细菌，分装两管，负80度冻存。
7.其余第7步的细菌库菌液(170ml)，加3ml辅助噬菌体(2.9x10 13/ml)，37度静止40分钟，37度250rpm培养40分钟。
8.离心收集经辅助噬菌体侵染的细菌，3500G离心15分钟，弃上清，用500ml 2YT-Amp-Kan培养液重悬细菌，30度250rpm培养过夜。
9.次日，根据第4步滴定铺皿结果，分析计算轻链置换细菌库库容，1.2x10 9。离心沉淀第10步培养过夜的细菌，取上清500ml与125ml 20％PEG-5M NaCl混匀，冰浴2小时，再离心收集轻链置换噬菌体库。
10.用5ml PBS悬起离心沉淀的轻链置换噬菌体库，用台式高速离心机，4度，18000g离心5分钟，取上清，测OD 280，计算轻链置换噬菌体库浓度：OD 280＝13.7,噬菌体浓度3.2x10 13/ml。
11.冻存轻链置换噬菌体库：5ml噬菌体库+2ml 80％高压灭菌甘油+0.5ml PBS＝7.5ml，混匀，分装0.5ml/1x10 13/管，负80度冻存。
实施例3构建多参比抗体重链置换基因库、细菌库和噬菌体库
1.用SfiI和Esp3I双酶切全人源重链可变区(Vh)亚库，制备Vh库插入片段。
2.参考实施例1记载的步骤，将得到的16个参比抗体轻链插入片段(第一多核苷酸)，Vh库插入片段(第二多核苷酸)与图1标示的第一载体多核苷酸，第二载体多核苷酸做4片段连接，构建轻链置换库。4个片段以1:1:1:1的分子数等比例混合，总量2345ng，20度连接过夜(15小时)。
3.纯化连接产物，得到1134ng重链置换库连接产物(基因库)。
4.转化3支TG1电感菌，菌液总量6000μl，37度/250rpm培养60分钟后，取10μl菌液做连接转化效率滴定。做8次10倍稀释，每个稀释度取5μl铺皿，32度培养过夜。
5.其余菌液，用220ml 2YT-Amp-2％glucose培养液稀释，37度250rpm培养3小时，测OD 600＝0.6(细菌库)。
6.取50ml第7步的细菌库菌液，转移到150ml摇瓶，37度250rpm继续培养4个小时，离心收菌，以4ml 2TY-Amp-7％DMSO悬起细菌，分装两管，负80度冻存。
7.其余第7步的细菌库菌液(170ml)，加3ml辅助噬菌体(2.9x10 13/ml)，37度静止40分钟，37度250rpm培养40分钟。
8.离心收集经辅助噬菌体侵染的细菌，3500G离心15分钟，弃上清，用500ml 2YT-Amp-Kan培养液重悬细菌，30度250rpm培养过夜。
9.次日，根据第4步滴定铺皿结果，分析计算重链置换细菌库库容，1.2x10 9。离心沉淀第10步培养过夜的细菌，取上清500ml与125ml 20％PEG-5M NaCl混匀，冰浴2小时，再离心收集重链置换噬菌体库。
10.用5ml PBS悬起离心沉淀的轻链置换噬菌体库，用台式高速离心机，4度，18000g离心5分钟，取上清，测OD 280，计算重链置换噬菌体库浓度：OD 280＝20.3,噬菌体浓度4.7x1013/ml。
11.冻存重链置换噬菌体库：5ml噬菌体库+2ml 80％高压灭菌甘油+0.5ml PBS＝7.5ml，混匀，分装0.5ml/1x10 13/管，负80度冻存。
实施例4制备携带参比抗体(Her3/Patritumab)Fab噬菌体展示载体的Tg1细菌，构建单参比抗体(Patritumab)轻链置换和重链置换基因库、细菌库和噬菌体库
1.参照实施例1的流程，制备携带参比抗体(Patritumab)Fab噬菌体展示载体的Tg1细菌。其中，Patritumab的相关CDR序列参见CN 102633881B。Patritumab的轻链重链序列参见US 7705130B2。
2.参照多参比抗体轻链重链置换库的构建流程构建单参比抗体Patritumab的轻链置换库和重链置换库。
3.轻链置换库和质量置换库两个连接体系，每个连接片段总量各1173ng，连接6小时，纯化连接产物，各得到550ng。
4.各取250ng，转化一支TG1电感菌。转化菌液体积各2ml，各取10μl做滴定，其余菌液各铺一个大皿一个中皿。32度培养过夜。
5.第二天，根据滴定结果计算细菌库库容，重链置换库2.4x10e8，轻链置换库4.4x 10e8。分别收集两个细菌库的全部菌落，每个库各配50ml培养液(2YT-0.2％glucose-Amp)，加入适量菌液，测定OD 600在0.12左右。
6. 37度250rpm培养50分钟，测定OD 600在0.25左右。各加250μl辅助噬菌体(OD280＝13)。混匀后37度静止培养30分钟，在37度250rpm培养30分钟。
7.离心收集细菌，各用100ml培养液(2YT-Amp-Kana)重悬细菌，30度250rpm培养6小时(3pm-9pm)。离心沉淀细菌，收集上清，各加25ml 5xPEG-NaCl，混匀后4度过夜沉淀噬菌体。
8.第三天，离心收集轻链置换噬菌体库和重链置换噬菌体库。各用2ml PBS悬起噬菌体库，各分装4管，负80度冻存。
实施例5构建单参比抗体(CD40/Secukinumab)重链置换基因库、细菌库和噬菌体库
1.参照多参比抗体重链置换库的构建流程(实施例3)构建单参比抗体Secukinumab的重链置换库。
2.参照实施例1的流程，将得到的Selicrelumab轻链插入片段(第一多核苷酸)，全人源Vh库插入片段(第二多核苷酸)与图1标示的第一载体多核苷酸，第二载体多核苷酸做4 片段连接，构建重链置换库。4个片段以1:1:1:1的分子数等比例混合，总量1175ng，20度连接过夜(15小时)。
3.纯化连接产物，得到513ng重链置换库连接产物(基因库)。
4.取300ng转化1支TG1电感菌，转化菌液总量2000μl，37度/250rpm培养60分钟后，取10μl菌液做连接转化效率滴定。做8次10倍稀释，每个稀释度取5μl铺皿，32度培养过夜。
5.其余菌液，均分铺两个大皿，32度培养过夜。
6.次日，根据第4步的滴定结果，分析计算重链置换库库容，3.2x10 8。收集第5步培养过夜的两个大皿的全部菌落，菌液总量15ml。测定收集菌液OD 600＝20。取3ml，加DMSO(终浓度7％)，分装两管，负80度冻存(细菌库)。
7.取200μl第6步收集的冻存菌液，加到50ml 2YT-Amp-0.2％glucose培养液，测定OD 600＝0.109，37度250rpm培养60分钟，测定OD 600＝0.247。
8.加250μl辅助噬菌体(OD280＝13)，混匀，37度静止30分钟，37度250rpm培养30分钟。
9.离心收集经辅助噬菌体侵染的细菌，重悬于100ml 2YT-Amp-Kana培养液，30度250rpm培养8小时。离心沉淀细菌，收集上清，与25ml 5x PEG-NaCL混匀，4度过夜沉淀噬菌体。
10.次日，离心沉淀第9步的噬菌体库，用2ml PBS悬起噬菌体沉淀，得到噬菌体库。测OD 280＝13，噬菌体浓度3x10 13/ml，取0.2ml重链置换噬菌体库用于第1轮筛选。
11.冻存重链置换噬菌体库：加0.6ml经高压消毒的80％的甘油溶液至甘油终浓度20％，混匀，分装4管，0.6ml/管，负80度冻存。
实施例6筛选CD40抗原特异性Selicrelumab轻链置换阳性克隆
准备抗原：
采购生物素标记的CD40抗原(AcroBio,Cat#：CD0-H82E8)和没有生物素标记的CD40抗原(AcroBio,Cat#：CD0-H5253)，按说明书要求溶解冻干粉，分装生物素标记抗原5μg/管，分装没有生物素标记抗原10μg/管，负80度保存。
第1轮筛选：
1.取负80度冻存的多参比抗体轻链置换噬菌体库一管(噬菌体浓度1x10 13/0.5ml，实施例2)，冰浴解冻，与100μl的MPBST(含12％Milk，0.05％Tween的1X PBS)混合，最终体积0.6ml，Milk终浓度2％。
2.加60μl已清洗重悬的磁珠(Invitrogen，Cat#：11206D)，室温转摇30分钟，吸附能与磁珠结合的非特异性噬菌体。
3.磁力架(Invitrogen Cat#：12321D)吸弃磁珠，转移噬菌体库溶液到新的经过2％MPBST封闭的2ml EP管。
4.取5μg生物素标记的抗原与轻链置换噬菌体库混合(最终抗原浓度5μg/0.6ml)，室温转摇2小时，展示抗原特异性Fab的噬菌体与生物素标记的抗原结合。
5.加60μl已清洗重悬的磁珠到噬菌体库溶液，室温转摇20分钟，通过磁珠表面的亲和素与生物素的结合捕获抗原特异性噬菌体，形成磁珠-亲和素-生物素-抗原-Fab抗体片段交联体。
6.通过磁力架收集第5步形成的携带抗原特异性Fab的交联体的磁珠。
7.用1xPBST洗磁珠4遍，再用1xPBS洗磁珠4遍。
8.用300μl pH2.2的甘氨酸溶液悬起磁珠，室温转摇10分钟，洗脱展示抗原特异性Fab的噬菌体。
9.通过磁力架收集磁珠，转移不含磁珠的洗脱上清到新的1.5ml EP管，用110μl pH8.0的Tris缓冲液中和至pH7.0。
10.用100μl pH2.2的甘氨酸溶液再次悬起磁珠，转摇5分钟，洗脱展示抗原特异性Fab的噬菌体。
11.通过磁力架收集磁珠，转移不含磁珠的洗脱上清到新的1.5ml EP管，用35μl pH8.0的Tris缓冲液中和至pH7.0。
12.合并第9步和第11步得到的中和洗脱噬菌体溶液约540μl，冰上保存备用。
13.预先培养40ml TG1细菌，监测OD600达到0.2-0.3。
14.取3ml TG1菌液，与400μl洗脱中和噬菌体溶液混合，37度静止30分钟。
15.取10μl噬菌体库侵染的菌液，用2YT培养液做8次10倍稀释，每个稀释度取5μl铺2YT-Amp平皿，32度培养过夜，做筛选效率滴定。
16.其余菌液，铺两个大方平皿(Thermo Cat#：8-1030-051)，32度培养过夜。
17. 4度保存剩余140μl洗脱中和噬菌体溶液。
18.次日，分析计算轻链置换噬菌体库第一轮筛选得到的噬菌体总数(output)为8.8 x 10 8。
包装扩增沉淀收集第1轮筛选得到的噬菌体库：
1.收集第一轮output两块大皿的菌落(最终菌液体积10ml)，取4ml冻存两管(2ml/7％DMSO/管)。
2.取20μl收集的菌液，用2YT做50倍稀释，测OD 600＝0.7，原菌液OD 600＝35。
3.配60ml 2YT-Amp-2％Glocose培养液，加200μl OD 600＝0.7的细菌库菌液，37度250rpm培养1小时，测OD 600在0.35左右。
4.加0.5ml辅助噬菌体(OD280＝13)，与细菌库菌液混合，MOI在500-1000之间。37度静止30分钟，37度250rpm培养30分钟。
5.离心收菌，用100ml 2YT-Amp-Kan培养液重悬细菌，30度250rpm培养过夜，包装扩增第一轮output噬菌体。
6.次日，4度9000rpm(贝克曼，JA-10)，离心15分钟，取上清与25ml 20％PEG-5M NaCl混匀，冰浴2个小时。
7. 4度9000rpm(贝克曼，JA-10)，离心15分钟，弃上清，4度再离心5分钟，将噬菌体沉淀集中到离心管底部，用枪头吸弃残留上清。
8.用2ml PBS悬起噬菌体库，用台式高速离心机，4度，18000g离心5分钟，取上清，测OD 280＝16，计算噬菌体浓度，3.73 x 10 13/ml。
9.取0.5ml噬菌体库，进行第二轮筛选。
10.其余噬菌体库，加1/3经高压消毒的80％的甘油溶液(甘油终浓度20％)，混匀，每个库分装三管，0.5ml/管，负80度冻存。
第2-5轮筛选：
1.取0.5ml扩增收集的第1轮筛选得到的噬菌体库，做第二轮筛选。筛选流程与第一轮筛选相同，但筛选时抗原终浓度为1μg/0.6ml，得到540μl洗脱中和噬菌体溶液。
2.取0.5ml第2轮洗脱中和噬菌体溶液，不做扩增，直接做第3轮筛选，筛选流程与第一轮筛选相同，筛选时抗原终浓度为1μg/0.6ml，得到270μl洗脱中和噬菌体溶液。
3.取200μl第3轮洗脱中和噬菌体溶液，侵染1ml TG1细菌，37℃30min，取10μl用于滴定，做8个梯度稀释，每个稀释度取5μl铺2YT-Amp平皿，32度培养过夜，做筛选效率滴定。其余菌液，750μl铺一大皿，250μl铺一大皿，32℃培养过夜。
4.次日，计算第3轮200μl洗脱中和噬菌体溶液含有的轻链置换噬菌体总数：2.6x 10 5。
5.包装扩增沉淀收集第3轮筛选得到的噬菌体库，流程与第1轮相同。
6.取0.5ml扩增收集的第3轮筛选得到的噬菌体库，做第4轮和第5轮筛选。筛选流程与第2轮第3轮筛选相同，筛选时抗原终浓度为1μg/0.6ml。
7.取200μl第5轮洗脱中和噬菌体溶液，侵染1ml TG1细菌，37℃30min，取10μl用于滴定，其余菌液，750μl铺一大皿，250μl铺一大皿，32℃培养过夜。
8.次日，计算第5轮200μl噬菌体溶液含有的轻链置换噬菌体总数：1.7 x 10 6。
接种深孔板，IPTG诱导Fab表达：
1.配制接种培养液2YT-Amp-0.2％Glucose，每块深孔板40ml，分装400μl/孔。
2.接种第5轮筛选菌落(一块深孔板)，用透气膜覆盖深孔板，37度，250rpm培养6个小时。
3.配制IPTG诱导培养液2YT-Amp-2mM-IPTG，每块深孔板40ml，加诱导培养液(400μl/孔)到已接种培养6个小时的深孔板(IPTG终浓度1mM)。
4.调整培养条件到30度，250rpm，诱导培养过夜。
5.配制CD40特异性抗原包被液(9.5ml ddH 2O+0.5ml 20x包被液+10μg没有生物素标记的CD40抗原)，包被1块ELISA板(100μl/孔)，4度包被过夜。
ELISA分析筛选CD40抗原特异性轻链置换阳性克隆：
1.配制3％MPBST(10ml/ELISA板)，PBST(200μl/每次洗板/孔)。
2.取出4度包被过夜的ELISA板，倾弃包被液，用PBST洗三次。
3.加3％MPBST(100μl/孔),用不透气膜覆盖，37度封闭60分钟。
4.倾弃封闭液，用PBST洗三次。
5.从诱导过夜的深孔板取混匀的菌液100μl/孔加到ELISA板的相应孔，用不透气膜覆盖，37度孵育60分钟。
6.倾弃菌液，用PBST洗三次。
7.配制二抗溶液：取5μl Anti-flag-HRP溶液(金斯瑞Cat#A0148-100，用ddH 2O溶解，0.5μg/μl)，加5ml PBS。将配制的二抗溶液加到ELISA板，50μl/孔，用不透气膜覆盖，37度孵育45分钟。
8.倾弃二抗溶液，用PBST洗三次。
9.加显色液(ABTS，Invitrogen，Cat#MD21704)，50μl/孔，室温显色30分钟。
10.加终止液(0.1M柠檬酸)，50μl/孔，混匀，读取OD 405数值。
11.测序分析OD 405大于1.2的克隆，得到43个Selicrelumab轻链置换阳性克隆，负80度冻存。
实施例7筛选CD40抗原特异性Selicrelumab重链置换阳性克隆
第一轮筛选：
取200μl(噬菌体浓度3x10 13/ml，实施例5)新鲜制备未加甘油的单参比抗体重链置换噬菌体库，与200μl的MPBST(含4％Milk，0.05％Tween的1X PBS)混合，最终体积0.4ml，Milk终浓度2％。
液相磁珠法筛选重链置换噬菌体，筛选流程与轻链置换噬菌体库第1轮筛选流程相同。抗原浓度1μg/400μl，最终洗脱中和噬菌体溶液540μl。取400μl洗脱中和液侵染1ml TG1细菌，取10μl菌液做滴定，取1ml菌液铺一个大皿，其余菌液铺另一个大皿，32度培养过夜。
重链链置换噬菌体库第1轮筛选得到的噬菌体总数(output)为8.5x 10 5。
包装扩增沉淀收集第1轮筛选得到的重链置换噬菌体库：
基本流程与第1轮筛选得到的轻链置换噬菌体库的包装扩增沉淀收集流程相同。简述如下：
收集铺1ml菌液大皿的全部菌落(6.3x10e5)，总体积8ml，冻存两管保种。取140μl收集的菌液与50ml培养液(2YT-A-G)混匀，测OD 600＝0.114，37度培养60分钟，测OD 600＝0.234，加250μl M13KO7辅助噬菌体(OD 280＝13)，混匀，37度静止30分钟，37度250rpm培养30分钟。离心收集细菌，重悬于100ml 2YT-Amp-Kana培养液，30度培养8小时。离心收集培养液上清，与25ml 5 x PEG-NaCl混匀，4度过夜沉淀噬菌体。次日，离心收集噬菌体库，用2ml PBS悬起，测OD280＝7，加甘油至终浓度20％，分装0.5ml/管，负80度冻存。
接种深孔板，IPTG诱导Fab表达：
接种重链置换噬菌体库第1轮筛选铺0.4ml菌液大皿的菌落(一块深孔板)，试剂材料准备及诱导表达Fab流程与轻链置换克隆相同。
ELISA分析筛选CD40抗原特异性重链置换阳性克隆：
筛选流程与分析筛选轻链置换克隆相同。
送样测序分析ELISA读数大于0.8的克隆，得到28个重链置换阳性克隆，负80度冻存。
实施例8筛选CD40抗原特异性Selicrelumab轻链重链双置换阳性克隆
制备轻链置换阳性克隆的轻链片段(参见图2，第三多核苷酸)和重链置换阳性克隆的重链可变区片段(参见图2，第四多核苷酸)：
室温化冻37个轻链置换阳性克隆(实施例6)和28个重链置换阳性克隆(实施例7)的冻存菌液，各取5μl混合，得到CD40-LC-ZH-M37菌液和CD40-VH-ZH-M28菌液。各取50μl混合菌液+500μl 2YT-Amp，混合后各铺一个大皿，32度培养过夜。
次日，收集两个大皿的全部菌落。各冻存两支，负80度保存。，
小提CD40-VH-ZH-M28(26μg)和CD40-LC-ZH-M37(32μg)的载体DNA。
用Esp3I和SfiI酶切5μg CD40-VH-ZH-M28载体DNA，电泳分析纯化M28-VH片段(324ng)(参见图2，第四多核苷酸)。
用SfiI酶切5μg CD40-LC-ZH-M37载体DNA，电泳分析纯化M37-LC片段(432ng)(参见图2，第三多核苷酸)。
构建轻链重链双置换库：
将制备的M37-LC插入片段(第三多核苷酸)，M28-VH插入片段(第四多核苷酸)与图2标示的第三载体多核苷酸，第四载体多核苷酸做4片段连接，构建轻链重链双置换基因。4个片段以1:1:1:1的分子数等比例混合，总量596ng，20度连接4小时。
纯化连接产物，得到450ng轻链重链双置换基因库。
取50ng纯化连接产物，转化一支TG1电感菌，滴定，铺皿，32度培养过夜。
次日，分析计算轻链重链双置换细菌库库容，2x10 6。
接种菌落，诱导Fab表达：
接种两块深孔板，IPTG 30度诱导培养过夜。CD40抗原包被两块ELISA板，100ng/孔，4度过夜。
ELISA分析筛选CD40抗原特异性轻链重链双置换阳性克隆：
分析筛选流程与单置换克隆相同。
送样测序分析ELISA读数大于1.5的阳性克隆，得到10个独特新VH，19个独特新LC，组成30个双置换阳性克隆，负80度冻存。
实施例9 CD40抗原特异性Selicrelumab轻链置换，重链置换，轻链重链双置换阳性克隆的功能分析
抗体表达：
选择确定通过293细胞瞬转表达纯化16个(#2-17)筛选到的ELISA读数与阳性对照相当的CD40抗原特异性阳性克隆的全长抗体(KLC/IgG1)，同时表达参比抗体Selicrelumab(#1)作为阳性对照。
1个阳性对照：Selicrelumab，#1；
6个轻链置换克隆：#2-7；
6个重链置换克隆：#8-13；
4个轻链重链双置换克隆：#14-17。
共得到15个纯化抗体(克隆#8和#17没有表达)
具体如表1所示：
表1
抗体表达编号 抗体表达类型 ELISA读数
阳性抗体 Selicrelumab 2.923
DDBK003-2 轻链置换 3.148
DDBK003-3 轻链置换 2.872
DDBK003-4 轻链置换 2.903
DDBK003-5 轻链置换 3.11
DDBK003-6 轻链置换 3.224
DDBK003-7 轻链置换 3.099
DDBK003-9 重链置换 3.205
DDBK003-10 重链置换 3.13
DDBK003-11 重链置换 3.175
DDBK003-12 重链置换 3.222
DDBK003-13 重链置换 3.326
DDBK003-14 轻链重链双置换 2.025
DDBK003-15 轻链重链双置换 1.839
DDBK003-16 轻链重链双置换 193
抗体激动活性分析：
参照参考文献(Scandinavian Journal of Immunology 65,479–486)，将抗体与人PBMC共培养五天(抗体浓度100nM)，检测培养液上清的IFN-γ浓度(pg/ml)，分析15个抗体的激动活性。结果显示，与阳性抗体Selicrelumab(#1)比较，全部14个筛选到的抗体均显示不同程度的激动活性，其中#2，3，4，5，6，7和#16的激动活性与阳性对照抗体相当。
结果如图4所示。
六个链置换功能抗体的Vh和全长轻链氨基酸序列：
两个轻链置换克隆#2，#3；两个重链置换克隆，#12，#13；两个轻链重链双置换克隆，#14，#16的氨基酸序列比对显示，与阳性对照抗体Selicrelumab的相应轻链或者重链氨基酸序列相比，筛选到的轻链(轻链置换克隆)，重链(重链置换克隆)，轻链和重链(轻链重链双置换克隆)，CDR区的氨基酸序列有显著不同。参见表2。
表2
Figure PCTCN2022084229-appb-000001
实施例10筛选Her3抗原特异性Patritumab轻链置换阳性克隆
参照实施例6的筛选流程，筛选Her3抗原特异性Patritumab轻链置换阳性克隆和重链置换阳性克隆。
取一支Patritumab轻链置换噬菌体库(实施例4)做第一轮筛选，得到的轻链置换噬菌体总数(output)为1 x 10 5。
收菌，扩增，包装第一轮output，得到第一轮output轻链置换噬菌体库，做第二轮和第三轮筛选。第三轮筛选轻链置换噬菌体总数(output)为2.2x10 7。
接种轻链置换噬菌体库克隆，2块深孔板，32度250rpm培养过夜，IPTG诱导Fab表达。
ELISA分析筛选Her3抗原特异性轻链置换阳性克隆，送样测序OD 405高的克隆共51个，得到独特轻链置换阳性克隆28个。
实施例11 Her3抗原特异性Patritumab轻链置换阳性克隆的功能分析
抗体表达：
选择确定通过293细胞瞬转表达纯化Patritumab(#1)和12个筛选到的ELISA读数与阳性对照相当的Her3抗原特异性轻链置换阳性克隆的全长抗体(#2-13，KLC/IgG1)。
抗体内吞活性分析：
复苏胃癌类器官(3-27-T)，培养7天；收集胃癌类器官，清洗除去基质胶，用无酚红D-Hanks悬液悬浮至合适体积，悬浮混匀；分装到96孔板，每孔50μL。
参照参考文献(ThermoFisher/Invitrogen，Zenon TM pHrodo TM iFL IgG Labeling Reagents，Catalog Nos.Z25609,Z25610,Z25611,Z25612，Pub.No.MAN0017436Rev.B.0)，配制160nM的抗体溶液和4x偶联试剂，将两者按1:1的比例混合，室温孵育5分钟。
将抗体-偶联试剂混合液加到已分装胃癌类器官的96孔板，酶孔50μl，室温孵育60分钟。
显微镜观察，拍照记录荧光场形态，分析抗体的内吞活性。
结果如图5所示。结果显示，DDBK004-2、DDBK004-3、DDBK004-7、DDBK004-13四个抗体有绿色荧光，提示有内吞活性，但弱于阳性对照；DDBK004-11的荧光强度与阳性对照相当，表明这个抗体的内吞活性与阳性抗体相当；DDBK004-9的荧光强度最强，高于阳性对照，表明这个抗体的内吞活性高于阳性对照。
上述抗体的CDR和可变区序列如表3所示：
表3
Figure PCTCN2022084229-appb-000002
实施例12筛选TIGIT抗原特异性参比抗体Tiragolumab轻链置换阳性克隆、重链置换阳性克隆和双置换阳性克隆，分析阳性克隆的生物学功能
筛选链置换阳性克隆：
参照实施例6准备抗原，从轻链置换噬菌体库和重链置换噬菌体库筛选TIGIT抗原特异性轻链置换阳性克隆和重链置换阳性克隆。
ELISA分析近1000个克隆。基于ELISA分析结果，参考阳性对照克隆的OD 405读数，选择读数较高的400余个克隆送样测序，确定TIGIT抗原特异性轻链置换阳性克隆和重链置换阳性克隆。
参照实施例8，选择轻链置换独特序列阳性克隆和重链置换独特序列阳性克隆，制备独特序列轻链片段(参见图2，第三多核苷酸)和重链片段(参见图2，第四多核苷酸)，与图2标示的第三载体多核苷酸，第四载体多核苷酸做4片段连接，构建轻重链双置换基因库、细菌库和噬菌体库，筛选得到双置换独特序列阳性克隆。
选择确定通过293细胞瞬转表达纯化15个(#2-16)筛选到的ELISA读数与阳性对照相当或更高的TIGIT抗原特异性阳性克隆的全长抗体(KLC/IgG1)，同时表达参比抗体Tiragolumab(#1)作为阳性对照。共得到15个纯化抗体(克隆#3没有表达)如表4所示：
表4
抗体表达编号 筛选克隆编号 抗体类型 ELISA OD 405读数
1 DDBJY38/39 阳性对照 0.499-2.867
2 TT128 轻链置换 2.949
3 TT261 轻链置换 3.349
4 TT194 轻链置换 2.89
5 TT233 轻链置换 3.139
6 TT216 轻链置换 3.122
7 TT210 轻链置换 2.84
8 TT174 轻链置换 3.249
9 TT255 轻链置换 3.173
10 TT321 重链置换 0.547
11 TT335 重链置换 0.669
12 TT357 重链置换 0.471
13 TT364 重链置换 1.165
14 TT385 重链置换 0.474
15 TT397 轻重链双置换 0.91
16 TT400 轻重链双置换 0.452
其中Tiragolumab的氨基酸序列参见WO2009126688A2。
抗体杀伤肿瘤细胞活性分析：
实验观察TIGIT抗体与PD-1抗体(Pembrolizomab)联用对非小细胞肺癌类器官的杀伤活性。基于多次预实验结果，表4中编号#5，10，12，14，15共5个抗体显示不同程度的杀伤活性。为比较并进一步确认预实验的结果，实验分TIGIT/PD-1抗体联用(1-8)和TIGIT抗体单用(9-16)两组，每组8个孔。
实验流程如下：
1，参照参考文献(Tumor organoid–T-cell coculture systems；NATURE PROTOCOLS|VOL 15 JANUARY 2020 15–39)，复苏非小细胞肺癌类器官(4-11-T)，在含IFNγ(200ng/mL)的培养液中培养24小时，收集类器官，清洗除去基质胶，用培养液悬浮至合适体积，混匀备用。
2，取PBMC(4-11-PBMC)计数，计算活力与细胞数，收集并洗涤，用T细胞培养液(RPMI1640，10％FBS，1％双抗，2mM谷氨酰胺，添加IL2)悬浮调整至合适浓度，分到96孔U型板，5x10 3PBMC/孔。
3，每孔加适量非小细胞肺癌类器官，调整至终体积200μL/孔。
4，孔1-8加PD-1抗体(Pembrolizomab)，终浓度100nM，然后从孔1到8依次加入阳性对照抗体(P)、Isotype抗体(I)、PBS以及5个预实验阳性克隆抗体，其中一个孔加PBS作为空白对照。孔9-16，不加PD-1抗体(Pembrolizomab)，其它试剂与孔1-8相同。结果如表5所示。
表5
Figure PCTCN2022084229-appb-000003
5，持续显微镜观察，定期拍照记录类器官和淋巴细胞变化，分析抗体对非小细胞肺癌类器官的杀伤活性。
6，TIGIT抗体单用的结果显示(图6)，与PBS空白对照和Isotype抗体比较，单独TIGIT抗体对非小细胞肺癌类器官没有明显的杀伤活性。
7，TIGIT抗体与PD-1抗体联用组的结果显示(图7)：
1)“阴性”对照孔(PD1+I；PD1+PBS)没有看到PD-1抗体单独对非小细胞肺癌类器官明显的杀伤活性；
2)阳性对照孔(PD1+P)，在第11天(D11)看到TIGIT抗体与PD-1抗体联用对非小细胞肺癌类器官具有明显的杀伤活性；
3)5个实验孔，TIGIT抗体#5、#10、#12、#14和#15与PD-1抗体联用(PD1+005，PD1+010，PD1+012，PD1+014，PD1+015)，对非小细胞肺癌类器官的杀伤活性与阳性对照(PD1+P)相当，在第11天(D11)看到明显的杀伤活性。
上述抗体的CDR和可变区序列如表6所示：
表6
Figure PCTCN2022084229-appb-000004
前述详细说明是以解释和举例的方式提供的，并非要限制所附权利要求的范围。目前本申请所列举的实施方式的多种变化对本领域普通技术人员来说是显而易见的，且保留在所附的权利要求和其等同方案的范围内。

Claims (132)

  1. 选择功能性抗原结合蛋白的方法，其包括，
    a)提供第一多核苷酸，所述第一多核苷酸以5’至3’方向包含R1-核酸片段I-R2，所述核酸片段I能够编码抗原结合片段I；
    b)提供第二多核苷酸，所述第二多核苷酸以5’至3’方向包含R3-参比核酸片段II-R4，所述参比核酸片段II能够编码参比抗原结合片段II，所述参比抗原结合片段II能够与由参比核酸片段I编码的参比抗原结合片段I形成参比抗原结合蛋白；
    c)提供第一载体多核苷酸，所述第一载体多核苷酸以5’至3’方向包含R2-载体片段I-R3；
    d)提供第二载体多核苷酸，所述第二载体多核苷酸以5’至3’方向包含R4-载体片段II-R1；
    e)用限制性核酸内切酶切割所述第一多核苷酸、所述第二多核苷酸、所述第一载体多核苷酸和所述第二载体多核苷酸，得到切割后的第一多核苷酸、切割后的第二多核苷酸、切割后的第一载体多核苷酸和切割后的第二载体多核苷酸；
    f)混合所述切割后的第一多核苷酸、所述切割后的第二多核苷酸、所述切割后的第一载体多核苷酸和所述切割后的第二载体多核苷酸，从而使得其能够定向连接而环化形成第一待筛选载体；
    g)使所述第一待筛选载体表达，选择能够表达具有以下性质的表达产物的第一待筛选载体为第一置换载体：能够结合所述参比结合蛋白能够结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上；
    h)从所述第一置换载体获得所述功能性抗原结合蛋白；
    其中，所述R1、R2、R3和R4各自独立地为限制性内切核酸酶识别位点。
  2. 根据权利要求1所述的方法，其包括用特异性识别所述R1和R2的限制性核酸内切酶切割所述第一多核苷酸，获得所述切割后的第一多核苷酸。
  3. 根据权利要求1-2中任一项所述的方法，其包括用特异性识别所述R3和R4的限制性核酸内切酶切割所述第二多核苷酸，获得所述切割后的第二多核苷酸。
  4. 根据权利要求1-3中任一项所述的方法，其包括用特异性识别所述R2和R3的限制性核酸内切酶切割所述第一载体多核苷酸，获得所述切割后的第一载体多核苷酸。
  5. 根据权利要求1-4中任一项所述的方法，其包括用特异性识别所述R4和R1的限制性核酸内切酶切割所述第二载体多核苷酸，获得所述切割后的第二载体多核苷酸。
  6. 根据权利要求1-5中任一项所述的方法，其中所述R1经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R2、R3和R4中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
  7. 根据权利要求1-6中任一项所述的方法，其中所述R2经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R1、R3和R4中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
  8. 根据权利要求1-7中任一项所述的方法，其中所述R3经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R1、R2和R4中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
  9. 根据权利要求1-8中任一项所述的方法，其中所述R4经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R1、R2和R3中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
  10. 根据权利要求1-9中任一项所述的方法，其中所述限制性内切核酸酶选自SfiI和BsmBI。
  11. 根据权利要求1-10中任一项所述的方法，其包括将所述第一待筛选载体导入细胞，使所述第一待筛选载体表达。
  12. 根据权利要求1-11中任一项所述的方法，其包括将所述第一待筛选载体导入细菌，制备包含一个或多个所述第一待筛选载体的噬菌体库，由所述噬菌体库获得所述功能性抗原结合蛋白。
  13. 根据权利要求1-12中任一项所述的方法，其中所述载体片段I包含连接子，且所述载体片段II源自展示载体。
  14. 根据权利要求13所述的方法，其中所述核酸片段I编码抗体轻链或其片段，所述载体片段I包含所述连接子，所述参比核酸片段II编码抗体重链或其片段，且所述载体片段II源自所述展示载体。
  15. 根据权利要求13-14中任一项所述的方法，其中所述R1包含SEQ ID NO:1所示的核苷酸序列。
  16. 根据权利要求13-15中任一项所述的方法，其中所述R2包含SEQ ID NO:2所示的核苷酸序列。
  17. 根据权利要求13-16中任一项所述的方法，其中所述R3包含SEQ ID NO:3所示的核苷酸序列。
  18. 根据权利要求13-17中任一项所述的方法，其中所述R4包含SEQ ID NO:4所示的核苷酸序列。
  19. 根据权利要求1-12中任一项所述的方法，其中所述载体片段II包含连接子，且所述载体片段I源自展示载体。
  20. 根据权利要求19所述的方法，其中所述核酸片段I编码抗体重链或其片段，所述载体片段I源自所述展示载体，所述参比核酸片段II编码抗体轻链或其片段，且所述载体片段II包含所述连接子。
  21. 根据权利要求19-20中任一项所述的方法，其中所述R1包含SEQ ID NO:3所示的核苷酸序列。
  22. 根据权利要求19-21中任一项所述的方法，其中所述R2包含SEQ ID NO:4所示的核苷酸序列。
  23. 根据权利要求19-22中任一项所述的方法，其中所述R3包含SEQ ID NO:1所示的核苷酸序列。
  24. 根据权利要求19-23中任一项所述的方法，其中所述R4包含SEQ ID NO:2所示的核苷酸序列。
  25. 根据权利要求13-24中任一项所述的方法，其中所述展示载体源自pComb3x载体。
  26. 根据权利要求13-25中任一项所述的方法，其中所述连接子包含编码信号肽pelB或其片段的核酸序列。
  27. 根据权利要求13-26中任一项所述的方法，其中所述连接子的长度为约50至约200个碱基。
  28. 根据权利要求1-11中任一项所述的方法，其包括将所述第一待筛选载体导入细菌，从所述细菌得到所述第一待筛选载体的DNA，将所述第一待筛选载体的DNA导入细胞；由所述细胞获得所述功能性抗原特异性结合多肽。
  29. 根据权利要求28所述的方法，其中所述细胞为哺乳动物细胞。
  30. 根据权利要求28-29中任一项所述的方法，其中所述载体片段I和/或所述载体片段II源自哺乳动物细胞表达载体。
  31. 根据权利要求28-30中任一项所述的方法，其中所述哺乳动物细胞表达载体源自pDGB4。
  32. 根据权利要求28-31中任一项所述的方法，其中所述核酸片段I编码抗体轻链或其片段，且所述参比核酸片段II编码抗体重链或其片段。
  33. 根据权利要求28-32中任一项所述的方法，其中所述R1包含SEQ ID NO:7所示的核苷酸序列。
  34. 根据权利要求28-33中任一项所述的方法，其中所述R2包含SEQ ID NO:8所示的核苷酸序列。
  35. 根据权利要求28-34中任一项所述的方法，其中所述R3包含SEQ ID NO:5所示的核苷酸序列。
  36. 根据权利要求28-35中任一项所述的方法，其中所述R4包含SEQ ID NO:6所示的核苷酸序列。
  37. 根据权利要求28-31中任一项所述的方法，其中所述核酸片段I编码抗体重链或其片段，且所述参比核酸片段II编码抗体轻链或其片段。
  38. 根据权利要求37所述的方法，其中所述R1包含SEQ ID NO:5所示的核苷酸序列。
  39. 根据权利要求37-38中任一项所述的方法，其中所述R2包含SEQ ID NO:6所示的核苷酸序列。
  40. 根据权利要求37-39中任一项所述的方法，其中所述R3包含SEQ ID NO:7所示的核苷酸序列。
  41. 根据权利要求37-40中任一项所述的方法，其中所述R4包含SEQ ID NO:8所示的核苷酸序列。
  42. 根据权利要求1-41中任一项所述的方法，其包括：
    a)提供第三多核苷酸，所述第三多核苷酸以5’至3’方向包含R5-核酸片段I’-R6；
    b)提供第四多核苷酸，所述第四多核苷酸以5’至3’方向包含R7-核酸片段II’-R8，所述核酸片段II’能够编码抗原结合蛋白II’，且所述抗原结合片段II’能够与所述参比抗原结合片段I形成具有以下性质的抗原结合蛋白：能够结合参比抗原结合蛋白能够结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上；
    c)提供第三载体多核苷酸，所述第三载体多核苷酸以5’至3’方向包含R6-载体片段III-R7；
    d)提供第四载体多核苷酸，所述第四载体多核苷酸以5’至3’方向包含R8-载体片段IV-R5；
    e)用限制性核酸内切酶切割所述第三多核苷酸、所述第四多核苷酸、所述第三载体多核苷酸和所述第四载体多核苷酸，得到切割后的第三多核苷酸、切割后的第四多核苷酸、切割后的第三载体多核苷酸和切割后的第四载体多核苷酸；
    f)混合所述切割后的第三多核苷酸、所述切割后的第四多核苷酸、所述切割后的第三载体多核苷酸和所述切割后的第四载体多核苷酸，从而使得其能够定向连接而环化形成双置换待筛选载体；
    g)使所述双置换待筛选载体表达，选择能够表达具有以下性质的表达产物的双置换待筛选载体为双置换载体：能够结合所述靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上；
    h)从所述双置换载体获得所述功能性抗原结合蛋白；
    其中，所述R5、R6、R7和R8各自独立地为所述限制性内切核酸酶识别位点。
  43. 根据权利要求42所述的方法，其包括用特异性识别所述R5和R6的限制性核酸内切酶切割所述第三多核苷酸，获得所述切割后的第三多核苷酸。
  44. 根据权利要求42-43中任一项所述的方法，其包括用特异性识别所述R7和R8的限制性核酸内切酶切割所述第四多核苷酸，获得所述切割后的第四多核苷酸。
  45. 根据权利要求42-44中任一项所述的方法，其包括用特异性识别所述R6和R7的限制性核酸内切酶切割所述第三载体多核苷酸，获得所述切割后的第三载体多核苷酸。
  46. 根据权利要求42-45中任一项所述的方法，其包括用特异性识别所述R8和R5的限制性核酸内切酶切割所述第四载体多核苷酸，获得所述切割后的第四载体多核苷酸。
  47. 根据权利要求42-46中任一项所述的方法，其中所述R5经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R6、R7和R8中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
  48. 根据权利要求42-47中任一项所述的方法，其中所述R6经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R5、R7和R8中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
  49. 根据权利要求42-48中任一项所述的方法，其中所述R7经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R5、R6和R8中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
  50. 根据权利要求42-49中任一项所述的方法，其中所述R8经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R5、R6和R7中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
  51. 根据权利要求42-50中任一项所述的方法，其中所述限制性内切核酸酶选自SfiI和BsmBI。
  52. 根据权利要求42-51中任一项所述的方法，其包括将所述双置换待筛选载体导入细胞，使所述双置换待筛选载体表达。
  53. 根据权利要求42-52中任一项所述的方法，其包括将所述双置换待筛选载体导入细菌，制备包含一个或多个所述双置换待筛选载体的噬菌体库，由所述噬菌体库获得所述功能性抗原结合蛋白。
  54. 根据权利要求42-53中任一项所述的方法，其中所述载体片段III包含连接子，且所述载体片段IV源自展示载体。
  55. 根据权利要求54所述的方法，其中所述核酸片段I’编码抗体轻链或其片段，所述载体片段III包含所述连接子，所述核酸片段II’编码抗体重链或其片段，且所述载体片段IV源自所述展示载体。
  56. 根据权利要求42-55中任一项所述的方法，其中所述R5包含SEQ ID NO:1所示的核苷酸序列。
  57. 根据权利要求42-56中任一项所述的方法，其中所述R6包含SEQ ID NO:2所示的核苷酸序列。
  58. 根据权利要求42-57中任一项所述的方法，其中所述R7包含SEQ ID NO:3所示的核苷酸序列。
  59. 根据权利要求42-58中任一项所述的方法，其中所述R8包含SEQ ID NO:4所示的核苷酸序列。
  60. 根据权利要求42-53中任一项所述的方法，其中所述载体片段IV包含连接子，且所述载体片段III源自展示载体。
  61. 根据权利要求60所述的方法，其中所述核酸片段I’编码抗体重链或其片段，所述载体片段III源自所述展示载体，所述核酸片段II’编码抗体轻链或其片段，且所述载体片段IV包含所述连接子。
  62. 根据权利要求60-61中任一项所述的方法，其中所述R5包含SEQ ID NO:3所示的核苷酸序列。
  63. 根据权利要求60-62中任一项所述的方法，其中所述R6包含SEQ ID NO:4所示的核苷酸序列。
  64. 根据权利要求60-63中任一项所述的方法，其中所述R7包含SEQ ID NO:1所示的核苷酸序列。
  65. 根据权利要求60-64中任一项所述的方法，其中所述R8包含SEQ ID NO:2所示的核苷酸序列。
  66. 根据权利要求54-65中任一项所述的方法，其中所述展示载体源自pComb3x载体。
  67. 根据权利要求54-66中任一项所述的方法，其中所述连接子包含编码信号肽pelB或其片段的核酸序列。
  68. 根据权利要求54-67所述的方法，其中所述连接子的长度为约50至约200个碱基。
  69. 根据权利要求42-52中任一项所述的方法，其包括将所述双展示待筛选载体导入细菌，从所述细菌得到所述双展示待筛选载体的DNA，将所述双展示待筛选载体的DNA导入细胞；由所述细胞获得所述功能性抗原特异性结合多肽。
  70. 根据权利要求69所述的方法，其中所述细胞为哺乳动物细胞。
  71. 根据权利要求69-70中任一项所述的方法，其中所述载体片段III和/或所述载体片段IV源自哺乳动物表达载体。
  72. 根据权利要求71所述的方法，其中所述哺乳动物表达载体源自pDGB4。
  73. 根据权利要求69-72中任一项所述的方法，其中所述核酸片段I’编码抗体轻链或其片段，且所述核酸片段II’编码抗体重链或其片段。
  74. 根据权利要求69-73中任一项所述的方法，其中所述R5包含SEQ ID NO:7所示的核苷酸序列。
  75. 根据权利要求69-74中任一项所述的方法，其中所述R6包含SEQ ID NO:8所示的核苷酸序列。
  76. 根据权利要求69-75中任一项所述的方法，其中所述R7包含SEQ ID NO:5所示的核苷酸序列。
  77. 根据权利要求69-76中任一项所述的方法，其中所述R8包含SEQ ID NO:6所示的核苷酸序列。
  78. 根据权利要求69-72中任一项所述的方法，其中所述核酸片段I’编码抗体重链或其片段，且所述核酸片段II’编码抗体轻链或其片段。
  79. 根据权利要求78所述的方法，其中所述R5包含SEQ ID NO:5所示的核苷酸序列。
  80. 根据权利要求78-79中任一项所述的方法，其中所述R6包含SEQ ID NO:6所示的核苷酸序列。
  81. 根据权利要求78-80中任一项所述的方法，其中所述R7包含SEQ ID NO:7所示的核苷酸序列。
  82. 根据权利要求78-81中任一项所述的方法，其中所述R8包含SEQ ID NO:8所示的核苷酸序列。
  83. 根据权利要求1-82中任一项所述的方法，其包括：
    a)提供第五多核苷酸，所述第五多核苷酸以5’至3’方向包含R9-参比核酸片段I-R10；
    b)提供第六多核苷酸，所述第六多核苷酸以5’至3’方向包含R11-核酸片段II-R12；
    c)提供第五载体多核苷酸，所述第五载体多核苷酸以5’至3’方向包含R10-载体片段V-R11；
    d)提供第六载体多核苷酸，所述第六载体多核苷酸以5’至3’方向包含R12-载体片段VI-R9；
    e)用限制性核酸内切酶切割所述第五多核苷酸、所述第六多核苷酸、所述第五载体多核苷酸和所述第六载体多核苷酸，得到切割后的第五多核苷酸、切割后的第六多核苷酸、切割后的第五载体多核苷酸和切割后的第六载体多核苷酸；
    f)混合所述切割后的第五多核苷酸、所述切割后的第六多核苷酸、所述切割后的第五载体多核苷酸和所述切割后的第六载体多核苷酸，从而使得其能够定向连接而环化形成第二待筛选载体；
    g)使所述第二待筛选载体表达，选择能够表达具有以下性质的表达产物的第二待筛选载体为第二置换载体：能够结合所述参比结合蛋白能够结合的靶标，且与所述靶标的结合能力为所述参比抗原结合蛋白与所述靶标结合能力的30％以上；
    h)选择所述第二置换载体的核酸片段II为所述核酸片段II’；
    其中，所述R9、R10、R11和R12各自独立地为限制性内切核酸酶识别位点。
  84. 根据权利要求83所述的方法，其包括用特异性识别所述R9和R10的限制性核酸内切酶切割所述第五多核苷酸，获得所述切割后的第五多核苷酸。
  85. 根据权利要求83-84中任一项所述的方法，其包括用特异性识别所述R11和R12的限制性核酸内切酶切割所述第六多核苷酸，获得所述切割后的第六多核苷酸。
  86. 根据权利要求83-85中任一项所述的方法，其包括用特异性识别所述R10和R11的限制性核酸内切酶切割所述第五载体多核苷酸，获得所述切割后的第五载体多核苷酸。
  87. 根据权利要求83-86中任一项所述的方法，其包括用特异性识别所述R12和R9的限制性核酸内切酶切割所述第六载体多核苷酸，获得所述切割后的第六载体多核苷酸。
  88. 根据权利要求83-87中任一项所述的方法，其中所述R9经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R10、R11和R12中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
  89. 根据权利要求83-88中任一项所述的方法，其中所述R10经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R11、R12和R9中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
  90. 根据权利要求83-89中任一项所述的方法，其中所述R11经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R9、R10和R12中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
  91. 根据权利要求83-90中任一项所述的方法，其中所述R12经特异性识别其的限制性核酸内切酶特异性切割后产生的末端不与所述R9、R10和R11中的任一项经相应限制性核酸内切酶特异性切割后产生的末端彼此识别或连接。
  92. 根据权利要求83-91中任一项所述的方法，其中所述限制性内切核酸酶选自SfiI和BsmBI。
  93. 根据权利要求83-92中任一项所述的方法，其包括将所述第二待筛选载体导入细胞，使所述第二待筛选载体表达。
  94. 根据权利要求83-93中任一项所述的方法，其包括将所述第二待筛选载体导入细菌，制备包含一个或多个所述第二待筛选载体的噬菌体库，由所述噬菌体库获得所述功能性抗原结合蛋白。
  95. 根据权利要求83-94中任一项所述的方法，其中所述载体片段V包含连接子，且所述载体片段VI源自展示载体。
  96. 根据权利要求95所述的方法，其中所述参比核酸片段I编码抗体轻链或其片段，所述载体片段V包含所述连接子，所述核酸片段II编码抗体重链或其片段，且所述载体片段VI源自所述展示载体。
  97. 根据权利要求83-96中任一项所述的方法，其中所述R9包含SEQ ID NO:1所示的核苷酸序列。
  98. 根据权利要求83-97中任一项所述的方法，其中所述R10包含SEQ ID NO:2所示的核苷酸序列。
  99. 根据权利要求83-98中任一项所述的方法，其中所述R11包含SEQ ID NO:3所示的核苷酸序列。
  100. 根据权利要求83-99中任一项所述的方法，其中所述R12包含SEQ ID NO:4所示的核苷酸序列。
  101. 根据权利要求83-94中任一项所述的方法，其中所述载体片段VI包含连接子，且所述载体片段V源自展示载体。
  102. 根据权利要求101所述的方法，其中所述参比核酸片段I编码抗体重链或其片段，所述载体片段V源自所述展示载体，所述核酸片段II编码抗体轻链或其片段，且所述载体片段VI包含所述连接子。
  103. 根据权利要求101-102中任一项所述的方法，其中所述R9包含SEQ ID NO:3所示的核苷酸序列。
  104. 根据权利要求101-103中任一项所述的方法，其中所述R10包含SEQ ID NO:4所示的核苷酸序列。
  105. 根据权利要求101-104中任一项所述的方法，其中所述R11包含SEQ ID NO:1所示的核苷酸序列。
  106. 根据权利要求101-105中任一项所述的方法，其中所述R12包含SEQ ID NO:2所示的核苷酸序列。
  107. 根据权利要求95-106中任一项所述的方法，其中所述展示载体源自pComb3x载体。
  108. 根据权利要求95-107中任一项所述的方法，其中所述连接子包含编码信号肽pelB或其片段的核酸序列。
  109. 根据权利要求95-108所述的方法，其中所述连接子的长度为约50至约200个碱基。
  110. 根据权利要求83-93中任一项所述的方法，其包括将所述第二待筛选载体导入细菌，从所述细菌得到所述第二待筛选载体的DNA，将所述第二待筛选载体的DNA导入细胞；由所述细胞获得所述功能性抗原特异性结合多肽。
  111. 根据权利要求110所述的方法，其中所述细胞为哺乳动物细胞。
  112. 根据权利要求110-111中任一项所述的方法，其中所述载体片段V和/或所述载体片段VI源自哺乳动物表达载体。
  113. 根据权利要求112所述的方法，其中所述哺乳动物表达载体源自pDGB4。
  114. 根据权利要求110-113中任一项所述的方法，其中所述参比核酸片段I编码抗体轻链或其片段，且所述参比片段II编码抗体重链或其片段。
  115. 根据权利要求110-114中任一项所述的方法，其中所述R9包含SEQ ID NO:7所示的核苷酸序列。
  116. 根据权利要求110-115中任一项所述的方法，其中所述R10包含SEQ ID NO:8所示的核苷酸序列。
  117. 根据权利要求110-116中任一项所述的方法，其中所述R11包含SEQ ID NO:5所示的核苷酸序列。
  118. 根据权利要求110-117中任一项所述的方法，其中所述R12包含SEQ ID NO:6所示的核苷酸序列。
  119. 根据权利要求110-113中任一项所述的方法，其中所述参比核酸片段I编码抗体重链或其片段，且所述核酸片段II编码抗体轻链或其片段。
  120. 根据权利要求119所述的方法，其中所述R9包含SEQ ID NO:5所示的核苷酸序列。
  121. 根据权利要求119-120中任一项所述的方法，其中所述R10包含SEQ ID NO:6所示的核苷酸序列。
  122. 根据权利要求119-121中任一项所述的方法，其中所述R11包含SEQ ID NO:7所示的核苷酸序列。
  123. 根据权利要求119-122中任一项所述的方法，其中所述R12包含SEQ ID NO:8所示的核苷酸序列。
  124. 根据权利要求1-123中任一项所述的方法，其中所述抗原结合蛋白包括抗体或抗体片段。
  125. 根据权利要求124所述的方法，其中所述抗体片段包含scFv，Fab，Fab’，(Fab) 2和/或(Fab’) 2。
  126. 根据权利要求1-125中任一项所述的方法，其中所述定向连接包括使用连接酶。
  127. 根据权利要求126所述的方法，其中所述连接酶为DNA连接酶。
  128. 制备抗原结合蛋白的方法，其包括在使得权利要求1-127中任一项所述的第一置换载体、权利要求83-127中任一项所述的第二置换载体和/或权利要求42-127中任一项所述的双置换载体表达的条件下，使权利要求1-127中任一项所述的第一置换载体、权利要求83-127中任一项所述的第二置换载体和/或权利要求42-127中任一项所述的双置换载体表达。
  129. 根据权利要求1-127中任一项所述的方法制备的第一置换载体。
  130. 根据权利要求83-127中任一项所述的方法制备的第二置换载体。
  131. 根据权利要求42-127中任一项所述的方法制备的双置换载体。
  132. 通过权利要求1-127中任一项所述的方法制备得到的功能性抗原结合蛋白。
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