TIGIT Fully Human Antibody, Its Preparation Method and Application

Abstract

This invention relates to a fully human TIGIT antibody, its preparation method, and its applications. The amino acid sequence of the fully human TIGIT antibody is one of SEQ ID NO. 31, SEQ ID NO. 32, SEQ ID NO. 33, SEQ ID NO. 34, SEQ ID NO. 35, SEQ ID NO. 36, SEQ ID NO. 37, and SEQ ID NO. 38. Compared to *Gynostemma pentaphyllum*, the fully human TIGIT antibody of this invention can better block the interaction between TIGIT and its ligand CD155. This helps to precisely regulate the immune response and reduce non-specific immunosuppression. Furthermore, the fully human TIGIT antibody, through its unique biological functions and synergistic effects with existing therapies, provides new hope and strategies for tumor immunotherapy.

Description

Technical Field

[0001] This invention relates to the field of antibody preparation technology, and in particular to a fully human TIGIT antibody, its preparation method, and its application. Background Technology

[0002] T / NK cells have many important molecules on their surface, which play a crucial role in their activation, proliferation, differentiation, and effector functions. TIGIT is a newly discovered cell surface protein with immunosuppressive functions.

[0003] TIGIT and CD155 exist as homodimers, and TIGIT binds to the CD155 homodimer through intermolecular interactions. CD155 is mainly expressed on the surface of immune cells such as dendritic cells (DCs), T cells, B cells, and macrophages, and is also expressed in small amounts on the surface of non-immune cells, such as those in the kidney, lung, and pancreas. CD112 is widely expressed on the surface of both hematopoietic and non-hematopoietic cells, but CD113 is expressed only on the surface of non-hematopoietic cells. Notably, CD155 and CD112 are highly expressed on the surface of many malignant tumors, such as colorectal cancer and melanoma. Therefore, in-depth research on TIGIT for the treatment of tumors and autoimmune diseases has both theoretical and practical significance. TIGIT antibody drugs, as novel immune checkpoint antibody drugs, have broad application prospects and can be used for the immunotherapy of tumors.

[0004] Monoclonal antibody drugs have potential immunogenicity, which may induce the production of anti-drug antibodies (ADAs) in the human body. ADAs can reduce the efficacy of drugs, and in more severe cases, cause hypersensitivity reactions. The closer the antibody gene source is to the human gene, the lower the immunogenicity, and the higher the efficacy and safety. From murine monoclonal antibodies to fully human monoclonal antibodies, the immunogenicity of biologics has been continuously reduced, providing patients with safer and more durable treatment options. Generally speaking, chimeric antibodies are 70% human in composition, humanized antibodies can reach a humanization level of 95%, while the amino acid sequence of fully human antibodies is 100% derived from humans. This difference in humanization level also determines the difference in antibody efficacy. Because fully human antibodies are entirely derived from the human body, they have the lowest rejection rate and the best safety profile.

[0005] Chinese patent CN116003606A discloses a TIGIT nanobody, its preparation method, and its application. The preparation process of the TIGIT nanobody in this patent is as follows: constructing a TIGIT antigen to immunize alpacas, obtaining alpaca PBMC cells; capturing RNA from the cells, reverse transcribing it into cDNA, performing PCR to obtain antibody gene fragments, and then expressing them using a mammalian cell high-throughput expression system; finally, screening for TIGIT nanobodies using ELISA and FACS detection. However, this patent uses TIGIT protein or DNA to immunize alpacas, establishes an immune library, and screens for anti-TIGIT protein nanobodies. Furthermore, the experiments in the patent only demonstrate cell binding and ELISA. Summary of the Invention

[0006] The purpose of this invention is to provide a fully human TIGIT antibody, its preparation method, and its applications. Compared with *Gynostemma pentaphyllum*, the fully human TIGIT antibody of this invention can better block the interaction between TIGIT and its ligand CD155. This helps to precisely regulate the immune response and reduce non-specific immunosuppression. In addition, the fully human TIGIT antibody, through its unique biological functions and synergistic effect with existing therapies, provides new hope and strategies for tumor immunotherapy.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] The first objective of this invention is to provide a fully human TIGIT antibody, wherein the fully human TIGIT antibody includes a framework region and a complementarity-determining region, and the complementarity-determining region includes CDR1, CDR2, and CDR3.

[0009] Wherein, the complementary decision region CDR1 sequence of VH is SEQ ID NO.1, the complementary decision region CDR2 sequence is SEQ ID NO.2, and the complementary decision region CDR3 sequence is SEQ ID NO.3;

[0010] Alternatively, the complementary decision region CDR1 described in VH is SEQ ID NO.11, the complementary decision region CDR2 is SEQ ID NO.12, and the complementary decision region CDR3 is SEQ ID NO.13;

[0011] Alternatively, the complementary decision region CDR1 described in VH is SEQ ID NO.1, the complementary decision region CDR2 is SEQ ID NO.17, and the complementary decision region CDR3 is SEQ ID NO.18;

[0012] Alternatively, the complementary decision region CDR1 described in VH is SEQ ID NO.22, the complementary decision region CDR2 is SEQ ID NO.23, and the complementary decision region CDR3 is SEQ ID NO.24;

[0013] VL's complementary decision region CDR1 is SEQ ID NO.4, complementary decision region CDR2 is SEQ ID NO.5, and complementary decision region CDR3 is SEQ ID NO.6;

[0014] Alternatively, the complementary decision region CDR1 described in VL is SEQ ID NO.7, the complementary decision region CDR2 is SEQ ID NO.5, and the complementary decision region CDR3 is SEQ ID NO.8;

[0015] Alternatively, the complementary decision region CDR1 described in VL is SEQ ID NO.4, the complementary decision region CDR2 is SEQ ID NO.5, and the complementary decision region CDR3 is SEQ ID NO.9;

[0016] Alternatively, the complementary decision region CDR1 described in VL is SEQ ID NO.4, the complementary decision region CDR2 is SEQ ID NO.5, and the complementary decision region CDR3 is SEQ ID NO.10;

[0017] Alternatively, the complementary decision region CDR1 described in VL is SEQ ID NO.14, the complementary decision region CDR2 is SEQ ID NO.15, and the complementary decision region CDR3 is SEQ ID NO.16;

[0018] Alternatively, the complementary decision region CDR1 described in VL is SEQ ID NO.19, the complementary decision region CDR2 is SEQ ID NO.20, and the complementary decision region CDR3 is SEQ ID NO.21;

[0019] Alternatively, the complementary decision region CDR1 described in VL is SEQ ID NO.25, the complementary decision region CDR2 is SEQ ID NO.26, and the complementary decision region CDR3 is SEQ ID NO.27;

[0020] Alternatively, the complementary decision region CDR1 described in VL is SEQ ID NO.28, the complementary decision region CDR2 is SEQ ID NO.29, and the complementary decision region CDR3 is SEQ ID NO.30.

[0021] As a preferred technical solution, the complementary decision region CDR1 sequence of VH is SEQ ID NO.1, the complementary decision region CDR2 sequence is SEQ ID NO.2, and the complementary decision region CDR3 sequence is SEQ ID NO.3;

[0022] VL's complementary decision region CDR1 is SEQ ID NO.4, complementary decision region CDR2 is SEQ ID NO.5, and complementary decision region CDR3 is SEQ ID NO.6;

[0023] Alternatively, the complementary decision region CDR1 described in VL is SEQ ID NO.7, the complementary decision region CDR2 is SEQ ID NO.5, and the complementary decision region CDR3 is SEQ ID NO.8;

[0024] Alternatively, the complementary decision region CDR1 described in VL is SEQ ID NO.4, the complementary decision region CDR2 is SEQ ID NO.5, and the complementary decision region CDR3 is SEQ ID NO.9;

[0025] Alternatively, the complementary decision region CDR1 of VL is SEQ ID NO.4, the complementary decision region CDR2 is SEQ ID NO.5, and the complementary decision region CDR3 is SEQ ID NO.10.

[0026] Further, the TIGIT human antibody has an amino acid sequence selected from any of the following: SEQ ID NO.31, SEQ ID NO.32, SEQ ID NO.33, SEQ ID NO.34, SEQ ID NO.35, SEQ ID NO.36, SEQ ID NO.37, SEQ ID NO.38.

[0027] As a preferred technical solution, the TIGIT human antibody has an amino acid sequence selected from any of the following: SEQ ID NO.31, SEQ ID NO.32, SEQ ID NO.33, SEQ ID NO.34.

[0028] Further, the nucleotide sequence encoding the amino acid sequence of the fully human TIGIT antibody is one of the following sequences: SEQ ID NO.39, SEQ ID NO.40, SEQ ID NO.41, SEQ ID NO.42, SEQ ID NO.43, SEQ ID NO.44, SEQ ID NO.45, SEQ ID NO.46.

[0029] As a preferred technical solution, the nucleotide sequence encoding the amino acid sequence of the TIGIT fully human antibody is one of the following sequences: SEQ ID NO.39, SEQ ID NO.40, SEQ ID NO.41, SEQ ID NO.42.

[0030] A second objective of the present invention is to provide a molecular expression vector comprising one of the nucleotide sequences of SEQ ID NO.39 to SEQ ID NO.46.

[0031] A third objective of the present invention is to provide a host cell containing the above-mentioned molecular expression vector, wherein the host cell is a mammalian cell.

[0032] Furthermore, the mammalian cells are selected from Expi 293F cells or CHO cells.

[0033] The fourth objective of this invention is to provide a method for preparing a fully human TIGIT antibody, the specific steps of which are as follows:

[0034] S1. Based on the protein and gene sequence information of TIGIT, express the screening antigen and link a His-tag to its C-terminus to obtain the modified nucleic acid sequence;

[0035] S2. The nucleic acid sequence obtained in step S1 is cloned into an expression vector, and the antigen is expressed using mammalian cells to obtain the TIGIT / His antigen.

[0036] S3. Using normal donor PBMC cells as raw materials, RNA was extracted and reverse transcribed into cDNA. Antibody gene fragments were obtained by PCR and cloned into a phage vector for library construction.

[0037] S4. Use the TIGIT / His antigen obtained in step S2 to screen for antibodies against the gene fragment library constructed in step S3.

[0038] S5. The antibody sequence obtained in step S4 is expressed through a mammalian cell system, and then a fully human antibody for TIGIT is obtained through screening. The fully human antibody for TIGIT has high sensitivity and specificity.

[0039] Further, in step S4, the sequence of the antibody gene fragment includes the nucleotide sequences shown in SEQ ID NO.39 to SEQ ID NO.46.

[0040] As a preferred technical solution, the sequence of the antibody gene fragment includes the nucleotide sequences shown in SEQ ID NO.39 to SEQ ID NO.42.

[0041] Furthermore, in step S5, further screening experiments include ELISA and FACS detection.

[0042] The fifth objective of this invention is to provide an application of the TIGIT fully human antibody in the preparation of a reagent for detecting T / NK cell surface proteins.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] The preparation method of the present invention is simple, and the antibody is expressed efficiently in mammalian cell expression systems. After translation, it can be processed and modified, and its activity is closer to that of natural antibodies.

[0045] Compared with the prior art, this invention utilizes fully human antibodies screened from a fully human library. The types of libraries and antibodies used in this invention are different from those in the prior art. The four fully human antibody sequences screened by this invention have a better blocking effect than Yangshen. The amino acid sequences of the fully human antibodies are 100% derived from humans, thus resulting in the lowest rejection reaction, the best safety profile, and better drug-like properties. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the experimental results of binding detection between HUMAN-TIGIT antigen (expressed TIGIT / His antigen) and antibodies (P2-D10, P1-H7, P2-A2 and P1-D1);

[0047] Figure 2 This is a schematic diagram of the experimental results of binding detection between HUMAN-TIGIT antigen (expressed TIGIT / His antigen) and antibodies (P1-A2, P1-H2, P2-D6 and P2-B10);

[0048] Figure 3 This is a schematic diagram of the experimental results of binding detection between HUMAN-TIGIT cell line (TCI / His antigen on cell surface) and antibodies (P1-D6, P2-B10, P2-D10, P1-H7, P2-A2 and P1-D1);

[0049] Figure 4 This is a schematic diagram of the results of the assay for the binding of HUMAN-TIGIT cell line (TCI / His antigen on cell surface) with antibodies (P1-A2 and P1-H2);

[0050] Figure 5 This is a schematic diagram of the results of the antibody binding assay for the CYNO-TIGIT cell line;

[0051] Figure 6 A schematic diagram of the results of antibody blocking assay at the cell level;

[0052] Figure 7 This is a schematic diagram of the results of the antibody blocking experiment at the protein level. Detailed Implementation

[0053] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0054] As used in this article, the terms "VH" and "VL" refer to the variable regions of the antibody heavy chain and light chain, respectively. Variable regions consist of discrete, well-defined subregions called complementarity-determining regions (CDRs, also known as HVRs) and framework regions (FRs). A CDR is an amino acid within the antibody variable region that confers antigen specificity and / or binding affinity, separated by FRs. Each antibody light chain variable region contains three CDRs (VLCDR1, VLCDR2, and VLCDR3), and each antibody heavy chain variable region contains three CDRs (VHCDR1, VHCR2, and VHCDR3). The complementarity-determining regions (CDRs) of the VH and VL regions alternate with more conserved regions of the framework regions (FRs). Each VH and VL consists of three CDRs and four FRs, arranged in the following order from the amino terminus to the carboxyl terminus: FR1, CDR1, FR2, CDR2, FR3, CDR3, and FR4.

[0055] As used herein, the term "expression" refers to the process by which a polypeptide is produced based on the coding sequence of a nucleic acid molecule, such as a gene. This process may include transcription, post-transcriptional control, post-transcriptional modification, translation, post-translational control, post-translational modification, or any combination thereof.

[0056] For any techniques or conditions not specified in this embodiment, the operation shall be carried out in accordance with conventional technical methods and instrument manuals in this field; for reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained commercially.

[0057] In the following embodiments, the amino acid sequences are shown in Table 1:

[0058] Table 1. Amino acid sequence of the CDR region of the TIGIT fully human antibody of this invention.

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0066] Example 1

[0067] This embodiment provides a method for preparing a fully human TIGIT antibody, the specific steps of which are as follows:

[0068] S1. Based on the protein and gene sequence information of TIGIT, its extracellular sequence was expressed, and a His-tag was ligated to its C-terminus. The expression vector was then cloned into pCDNA3.4, and antigen expression was performed using mammalian Expi 293F cells to obtain the TIGIT / His antigen for subsequent screening and detection.

[0069] S2. Using normal donor PBMC cells (purchased from Miaoshun Biotechnology Co., Ltd.) as raw materials, RNA was extracted from the obtained cells using the Trizol method and reversed into cDNA using oligo(dT). Gene fragments were obtained by PCR amplification and then cloned into the phage vector pComb3XSS (purchased from Addgene) for library construction.

[0070] S3. Use the TIGIT / His antigen obtained in step S1 to screen for antibodies.

[0071] S3-1, First Round of Screening

[0072] S3-1-1. Prepare two labeled immunoassay tubes (one for positive screening and one for negative screening). Place them in a clean bench and wash twice with PBST and twice with PBS.

[0073] Coating antigen: Dilute the TIGIT / His antigen expressed in step S1 with PBS, 50 μg / 2 ml / tube, and rotate overnight at 4°C for coating.

[0074] S3-1-2. On the second day, recover the antigen, wash 3 times with PBST, wash twice with PBS, and add 5×10 to the negative sieve tube. 12 (5×10 12 / 1.5×10 13 The packaged phage obtained in step S2 was sealed with 1% BSA to a final volume of 4 ml. Simultaneously, only 4 ml of 1% BSA was added to the positive sieve tube for sealing, and the tubes were incubated at room temperature for 1 hour by rotation.

[0075] S3-1-3. After sealing, take the supernatant PHAGE from the negative sieve tube and add it to the positive sieve immunotherapy tube. Incubate at room temperature for 1 hour by rotation. Remove the supernatant, add PBST to wash 8 times, and then wash twice with PBS.

[0076] S3-1-4, Elute the bound phage, add 1 ml of trypsin to elute, and incubate at room temperature for 30 min by rotation.

[0077] S3-1-5, Infection: Add 500 μl of the phage elution mixture to 5 ml of shaken SS320 bacterial suspension (purchased from Lucigen) (OD600: 0.4-0.6), mix well, and incubate at 37°C for 30 min. Simultaneously, add 10 μl of the remaining 500 μl of phage elution to the shaken SS320 bacterial suspension, perform a 10-fold serial dilution (8-9 dilutions), and incubate at 37°C for 30 min.

[0078] S3-1-6. After infection, the bacterial suspension is centrifuged at 3000 rpm for 5 min to enrich the bacterial cells. The supernatant is discarded, and the bacterial cells are resuspended in about 300 μl of culture medium. The suspension is then plated (2YT plates with A+ and T+). The plates are inverted and placed in a 37°C incubator overnight. Titters are also added at the same time.

[0079] S3-2, Second Round of Selection

[0080] The differences from the first round of screening are shown in Table 2 below.

[0081] S3-3, Third Round of Selection

[0082] The differences from the first round of screening are shown in Table 2 below.

[0083] Table 2. Differences among the three rounds of solid phase screening

[0084] Rounds Input phage(pfu) Amount of coating antigen (μg) Round 1 <![CDATA[~5×10 12 ]]> 50 2 rounds <![CDATA[~5×10 11 ]]> 30 3 rounds <![CDATA[~5×10 10 ]]> 15

[0085] S4. ELISA screening of the positive clones prepared in step S3 yields antibodies (P2-D10, P1-H7, P2-A2, P1-D1, P1-A2, P1-H2, P2-D6, and P2-B10). The specific detection process is as follows:

[0086] S4-1: Coat the enzyme-labeled plate with the TIGIT / His antigen expressed in step S1 at a concentration of 1 μg / mL and incubate overnight at 4°C.

[0087] S4-2, Wash three times with PBST on the second day, then block with 1% BSA at room temperature for 1 hour;

[0088] Wash three times with S4-3 and PBST, add 200 μl of overnight shaken monoclonal supernatant to each well, and incubate at 37°C for 1.5 h;

[0089] Wash three times with S4-4 and PBST, add Anti-FLAG-HRP secondary antibody diluted 1:10000 to each well, and incubate at 37℃ for 1 h;

[0090] Wash three times with S4-5 PBST, add 100 μL of TMB substrate, incubate at 37 °C for 10 min, add 50 μL of 0.1 M H2SO4 to stop the reaction, and measure OD at 450 nm.

[0091] S5. Plasmid construction and extraction: Construction of positive antibody sequences and cloning into expression vectors.

[0092] The antibody sequences (SEQ ID NO.39~SEQ ID NO.46) obtained by screening were cloned into the pCDNA3.4 expression vector to obtain antibodies (P2-D10, P1-H7, P2-A2, P1-D1, P1-A2, P1-H2, P2-D6 and P2-B10).

[0093] S6. Cell transfection: Seed cells to an appropriate density the day before transfection, using a heavy chain to light chain molar ratio of 2:3. Culture at 37°C in a 5% CO2 cell incubator for 12 consecutive days.

[0094] S7. The antibody obtained in step S6 is expressed and then used to detect its binding with the TIGIT protein (i.e., the TIGIT / His antigen obtained in step S1). ELISA results show (e.g.) Figure 1 and Figure 2 As shown in the figure, the ELISA results of the selected antibody sequences P2-D10, P1-A2, P1-H7, and P2-A2 were better than those of Tiragolumab. To further verify the binding of positive antibodies, a cell binding assay was performed. The selected antibodies were added to pre-coated cells at a starting price of 200 nM and serially diluted 3-fold. The cells were incubated at 4°C for 1 hour, washed twice with a MACS buffer (PBS + 10% FBS + 2 mM EDTA), and then the secondary antibody (Goat anti-Human IgG (H+L) Cross-Adsorbed Secondary Antibody, Alexa Fluor 488 (imported, purchased from Thermo) was added. The cells were incubated at 4°C for 30 minutes, washed twice with a MACS buffer, and then analyzed by flow cytometry. The results showed... Figure 3 and Figure 4 The results showed that the fully human antibody obtained through CELL BINDING ASSAY screening had a better cell binding effect than the control antibody.

[0095] S8. Select antibody sequences (P2-D10, P1-A2, P1-H7, and P2-A2) with CELL BINDING ASSAY results lower than those of *C. yanghen* for species experiments. Start with 200 nM of the selected antibodies, dilute them 3-fold serially, and add them to pre-seeded cells (CYNO-TIGIT-CHOK1 CELL LINE). Incubate at 4°C for 1 hour, wash twice with a MACS buffer, add secondary antibody, incubate at 4°C for 30 minutes, wash twice with a MACS buffer, and analyze by flow cytometry. The results show... Figure 5 The results showed that both the EC50 of the antibody sequence and the cynomolgus virus could bind to CYNOMOLGUS.

[0096] S9. Select antibody sequences (P2-D10, P1-A2, P1-H7, and P2-A2) that showed better cell binding assay results than those of *C. yangshen* for cell-level blocking experiments. Incubate cells with the ligand CD155 (gene sequence from UNIPROT) at a working concentration of 20 μg / ml. Simultaneously, add the antibody in a 3-fold serial dilution starting at 200 nM to the cells. Incubate at 4°C for 1 hour, wash twice with a MACS buffer, add the secondary antibody, incubate at 4°C for 30 minutes, wash twice with a MACS buffer, and analyze by flow cytometry. The results show... Figure 6 The results showed that the selected sequences had a stronger blocking effect than the positive reference.

[0097] S10. Select antibody sequences (P2-D10, P1-A2, P1-H7, and P2-A2) with EC50 values ​​lower than those of *Cell Binding Assay* for protein-level blocking experiments. Incubate the ligand CD155 at a working concentration of 20 μg / ml with the TIGIT / His antigen expressed in step S1 of the previous day's plating. Simultaneously, add the antibody to the antigen in a 3-fold serial dilution starting at 200 nM. Incubate at 37°C for 1 hour, wash three times with PBST, add secondary antibody, incubate at 37°C for 45 minutes, wash three times with PBST, add 50 μL of chromogenic buffer (TMB chromogenic buffer, purchased from Beyotime), incubate at 37°C for 5 minutes, add stop chromogenic buffer, and read the values ​​on the instrument. The results are as follows: Figure 7 The results showed that the selected sequences had a stronger blocking effect than the positive reference.

[0098] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A fully human TIGIT antibody, characterized in that, The TIGIT fully human antibody includes a framework region and a complementation-determining region (CDR). The CDR includes CDR1, CDR2, and CDR3 for VH and CDR1, CDR2, and CDR3 for VL. Among them, the CDR1 sequence of the complementarity-determining region (CDR1) of VH is SEQ ID NO.1, the CDR2 sequence of VH is SEQ ID NO.2, and the CDR3 sequence of VH is SEQ ID NO.

3. The complementary determinant region CDR1 of VL is SEQ ID NO.4, the complementary determinant region CDR2 of VL is SEQ ID NO.5, and the complementary determinant region CDR3 of VL is SEQ ID NO.6; Alternatively, the CDR1 sequence of VH's complementarity-determining region is SEQ ID NO.1, the CDR2 sequence of VH's complementarity-determining region is SEQ ID NO.2, and the CDR3 sequence of VH's complementarity-determining region is SEQ ID NO.

3. The complementary determinant region CDR1 of VL is SEQ ID NO.7, the complementary determinant region CDR2 of VL is SEQ ID NO.5, and the complementary determinant region CDR3 of VL is SEQ ID NO.8; Alternatively, the CDR1 sequence of VH's complementarity-determining region is SEQ ID NO.1, the CDR2 sequence of VH's complementarity-determining region is SEQ ID NO.2, and the CDR3 sequence of VH's complementarity-determining region is SEQ ID NO.

3. The complementary determinant region CDR1 of VL is SEQ ID NO.4, the complementary determinant region CDR2 of VL is SEQ ID NO.5, and the complementary determinant region CDR3 of VL is SEQ ID NO.9; Alternatively, the CDR1 sequence of VH's complementarity-determining region is SEQ ID NO.1, the CDR2 sequence of VH's complementarity-determining region is SEQ ID NO.2, and the CDR3 sequence of VH's complementarity-determining region is SEQ ID NO.

3. The complementarity determination region CDR1 of VL is SEQ ID NO.4, the complementarity determination region CDR2 of VL is SEQ ID NO.5, and the complementarity determination region CDR3 of VL is SEQ ID NO.

10.

2. The TIGIT fully human antibody according to claim 1, characterized in that, The TIGIT human antibody has an amino acid sequence selected from any of the following: SEQ ID NO.31, SEQ ID NO.32, SEQ ID NO.33, SEQ ID NO.

34.

3. The TIGIT fully human antibody according to claim 2, characterized in that, The nucleotide sequence encoding the amino acid sequence of the fully human TIGIT antibody is one of the following sequences: SEQ ID NO.39, SEQ ID NO.40, SEQ ID NO.41, or SEQ ID NO.

42.

4. A molecular expression vector, characterized in that, The vector contains one of the nucleotide sequences of SEQ ID NO.39 to SEQ ID NO.

42.

5. A host cell containing the molecular expression vector of claim 4, characterized in that, The host cell is a mammalian cell.

6. The host cell according to claim 5, characterized in that, The mammalian cells were selected from Expi 293F cells or CHO cells.

7. The use of the TIGIT fully human antibody as described in any one of claims 1 to 3 in the preparation of a reagent for detecting T / NK cell surface proteins.

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