CN112279915A

CN112279915A - ICOS antibodies, genes, vectors, host cells and ICOS antagonists

Info

Publication number: CN112279915A
Application number: CN201910676478.9A
Authority: CN
Inventors: 张欣; 费烨琼; 宁姗姗; 赵猛; 马树立
Original assignee: Dingfu Biotarget Co ltd
Current assignee: Dingfu Biotarget Co ltd
Priority date: 2019-07-25
Filing date: 2019-07-25
Publication date: 2021-01-29

Abstract

The invention relates to the technical field of antibodies, in particular to an ICOS antibody, a gene, a vector, a host cell and an ICOS antagonist. The heavy chain of the ICOS antibody comprises SEQ ID NO: 1, CDR1 of the sequence shown in SEQ ID NO: 2, CDR2 of the sequence shown in SEQ ID NO: 3 CDR3 of the sequence shown in seq id no; the light chain of the ICOS antibody comprises SEQ ID NO: 4, CDR4 of the sequence shown in SEQ ID NO: 5, CDR5 of the sequence shown in SEQ ID NO: 6, CDR6 of the sequence shown in seq id no. The ICOS antibody of the invention can be specifically combined with cell surface hICOS, and can be used as an antagonist of ICOS signal transduction, so that the antibody can be used for treating ICOS related diseases, such as cancer.

Description

ICOS antibodies, genes, vectors, host cells and ICOS antagonists

Technical Field

The invention relates to the technical field of antibodies, in particular to an ICOS antibody, a gene, a vector, a host cell and an ICOS antagonist.

Background

T cell activation requires, in addition to a first signal provided by TCR-CD3, a second signal generated by the interaction of a costimulatory molecule on the surface of an antigen-presenting cell or target cell with a corresponding costimulatory molecule receptor on the surface of the T cell. ICOS is the third member of the CD28 family, belonging to the immunoglobulin superfamily, expressed only in activated T cells and is therefore called an inducible costimulatory molecule (Hutloff A. et al. Nature,1999,397: 263-266.). The ligand ICOSL (also called B7H2, GL50) is a member of a B7 family, has higher homology with B7-1/B7-2 (Ling V.et al.J.Immunol,2000,164: 1653) -1657), and is mainly expressed on the surfaces of B cells, monocytes, APC and endothelial cells. The research shows that ICOS has the function of positively stimulating T cells, can promote the activation and proliferation of T cells, can promote the secretion of cytokines such as IFN gamma, TNF alpha, IL2, IL4, IL13 and the like, can promote the exertion of T cell functions (Hutloff A.et al Nature,1999,397:263-266.Dong C.et al 2001,409:97-101.), can promote the differentiation and development of B cells and the secretion of antibodies (Dong C, et al.J. Immunol,2001,166:3659-3662.) and the like.

There is increasing evidence that anti-ICOS antibodies can achieve good anti-tumor effects in combination with immune checkpoint inhibitor CTLA4 blockers in mouse tumor models and clinical treatments. In mouse melanoma tumor models lacking ICOS or ICOSL, the anti-tumor capacity of anti-CTLA 4 antibodies was reduced (FuT, et al. cancer res.2011,71(16):5445-54.), while in normal mice ICOS signaling activation enhanced the anti-tumor capacity against CTLA4 in melanoma (Fan X, et al. j Exp med 2014,211(4): 715-25.). In clinical trials, it was observed that ICOS expression of CD4T cells was upregulated and CD4T cells secreting the majority of tumor-specific IFN γ were ICOS-positive in patients with advanced melanoma and bladder cancer, among others, following treatment with Ipilimumab (anti-CTLA 4 mab), and that a sustained elevation of ICOS-positive CD4T was associated with patient survival (Fan X, et al.j Exp med.2014,211(4):715-725.Liakou CI, et al.proc Natl Acad scias usa.2008,105(39): 14987-92.). Clinical trials of the other antibody CTLA4 antibody Tremelimumab in breast Cancer patients have shown that ICOS-positive CD4T cells are associated with prognosis, ICOS being an immune activation signal following CTLA4 blockade (von dehidede RH, et al. clin Cancer res.2010,16(13): 3485-94.). Antagonists of ICOS signaling would therefore be useful in the treatment of ICOS-related diseases, such as cancer.

Disclosure of Invention

In view of the above, the present invention provides ICOS antibodies, genes, vectors, host cells and ICOS antagonists. The ICOS antibody can be specifically combined with cell surface hICOS, and can be used as an antagonist for ICOS signal transduction.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides an ICOS antibody, the heavy chain of which comprises SEQ ID NO: 1, CDR1 of the sequence shown in SEQ ID NO: 2, CDR2 of the sequence shown in SEQ ID NO: 3 CDR3 of the sequence shown in seq id no;

the light chain of the ICOS antibody comprises SEQ ID NO: 4, CDR4 of the sequence shown in SEQ ID NO: 5, CDR5 of the sequence shown in SEQ ID NO: 6, CDR6 of the sequence shown in seq id no.

In the invention, the heavy chain and the light chain of the ICOS antibody are connected by a linker, and the amino acid sequence of the linker is shown as SEQ ID NO: shown at 7.

The invention also provides an ICOS antibody, wherein the amino acid sequence of the ICOS antibody is shown in SEQ ID NO: shown in fig. 8.

Preferably, the ICOS antibody is a humanized antibody.

The invention also provides a gene for coding the ICOS antibody, and the base sequence of the gene is shown as SEQ ID NO: shown at 9.

The invention also provides a vector comprising a gene encoding an ICOS antibody.

Preferably, the plasmid used for the vector is pcDNA 4/myc-HisA.

The invention also provides a host cell comprising the vector.

Preferably, the host cell is a HEK293 cell.

The invention also provides a preparation method of the ICOS antibody, which comprises the following steps: after fusion of scFv gene (shown in SEQ ID NO: 9) and IgG1-Fc gene, the single-chain antibody was cloned into vector pcDNA4/myc-HisA by HindIII and EcoRI double digestion, cloning and plasmid miniextraction were carried out, the extracted plasmid was expressed in HEK293 cells and purified by protein A column.

The invention also provides an ICOS antagonist, comprising the ICOS antibody provided by the invention.

The invention provides ICOS antibodies, genes, vectors, host cells and ICOS antagonists. The heavy chain of the ICOS antibody comprises SEQ ID NO: 1, CDR1 of the sequence shown in SEQ ID NO: 2, CDR2 of the sequence shown in SEQ ID NO: 3 CDR3 of the sequence shown in seq id no; the light chain of the ICOS antibody comprises SEQ ID NO: 4, CDR4 of the sequence shown in SEQ ID NO: 5, CDR5 of the sequence shown in SEQ ID NO: 6, CDR6 of the sequence shown in seq id no. The invention has the technical effects that:

the ICOS antibody of the invention can be specifically combined with cell surface hICOS, and can be used as an antagonist of ICOS signal transduction, so that the antibody can be used for treating ICOS related diseases, such as cancer.

Drawings

FIG. 1 shows the results of characterization of anti-ICOS antibody, where 1-1 is blank control, 1-2 is negative control, and 1-3 is flow cytogram of anti-hICOS scFv antibody bound to cell surface hICOS.

Detailed Description

Antibodies to ICOS, genes, vectors, host cells and antagonists of ICOS are disclosed, and can be achieved by those skilled in the art by appropriate modification of the process parameters in view of the disclosure herein. It is expressly intended that all such similar substitutes and modifications which would be obvious to one skilled in the art are deemed to be included in the invention. While the methods and applications of this invention have been described in terms of preferred embodiments, it will be apparent to those of ordinary skill in the art that variations and modifications in the methods and applications described herein, as well as other suitable variations and combinations, may be made to implement and use the techniques of this invention without departing from the spirit and scope of the invention.

Reagents, instruments and materials used in the ICOS antibodies, genes, vectors, host cells and ICOS antagonists provided by the invention are commercially available.

The invention is further illustrated by the following examples:

example 1: expression of recombinant human ICOS and EGFP cell preparation

Obtaining the amino acid sequence of the human ICOS extracellular domain (namely residue 1 to residue 140 in Q9Y6W8) according to the amino acid sequence (Q9Y6W8) of the human ICOS on a protein database Unit; the amino acid sequence of ICOS is as follows (wherein the underlined part is the extracellular domain):

MKSGLWYFFLFCLRIKVLTGEINGSANYEMFIFHNGGVQILCKYPDIVQQFKMQLLKGGQILCDLTKTK GSGNTVSIKSLKFCHSQLSNNSVSFFLYNLDHSHANYYFCNLSIFDPPPFKVTLTGGYLHIYESQLCCQLKFWLPIGCAAFVVVCILGCILICWLTKKKYSSSVHDPNGEYMFMRAVNTAKKSRLTDVTL

the base sequence is as follows:

atgaagtcaggcctctggtatttctttctcttctgcttgcgcattaaagttttaacaggagaaatcaa tggttctgccaattatgagatgtttatatttcacaacggaggtgtacaaattttatgcaaatatcctgacattgtc cagcaatttaaaatgcagttgctgaaaggggggcaaatactctgcgatctcactaagacaaaaggaagtggaaaca cagtgtccattaagagtctgaaattctgccattctcagttatccaacaacagtgtctctttttttctatacaactt ggaccattctcatgccaactattacttctgcaacctatcaatttttgatcctcctccttttaaagtaactcttaca ggaggatatttgcatatttatgaatcacaactttgttgccagctgaagttctggttacccataggatgtgcagcctttgttgtagtctgcattttgggatgcatacttatttgttggcttacaaaaaagaagtattcatccagtgtgcacgaccctaacggtgaatacatgttcatgagagcagtgaacacagccaaaaaatctagactcacagatgtgaccctataa

the amino acid sequence of the domain of human IgG1-Fc (i.e., residues 104 to 330 in P01857) was obtained from the amino acid sequence of the constant region of human immunoglobulin gamma (gamma) 1(IgG1) on Unit protein database (P01857). The IgG1-Fc amino acid sequence is as follows:

DKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK

the base sequence is as follows:

gacaaaactcacacatgcccaccgtgcccagctccggaactcctgggcggaccgtcagtcttcctcttccccccaaaacccaaggacaccctcatgatctcccggacccctgaggtcacatgcgtggtggtggacgtgagccacgaagaccctgaggtcaagttcaactggtacgtggacggcgtggaggtgcataatgccaagacaaagccgcgggaggagcagtacaacagcacgtaccgtgtggtcagcgtcctcaccgtcctgcaccaggactggctgaatggcaaggagtacaagtgcaaggtctccaacaaagccctcccagcccccatcgagaaaaccatctccaaagccaaagggcagccccgagaaccacaggtgtacaccctgcccccatcccgggatgagctgaccaagaaccaggtcagcctgacctgcctggtcaaaggcttctatcccagcgacatcgccgtggagtgggagagcaatgggcagccggagaacaactacaagaccacgcctcccgtgttggactccgacggctccttcttcctctacagcaagctcaccgtggacaagagcaggtggcagcaggggaacgtcttctcatgctccgtgatgcatgaggctctgcacaaccactacacgcagaagagcctctccctgtctccgggtaaa

a DNAworks online tool (http:// helix web. nih. gov/DNAworks /) is utilized to design a corresponding coding DNA sequence to obtain the gene of the hICOS-Fc fusion protein.

Obtaining an enhanced green fluorescent protein EGFP amino acid sequence (C5MKY7) and an amino acid sequence (Q9Y6W8) of human ICOS according to information on a protein database Unit, wherein the EGFP amino acid sequence is as follows: MVSKGEELFTGVVPILVELDGDVNGHKFSVSGEGEGDATYGKLTLKFICTTGKLPVPWPTLVTTLTYGVQCFSRYPDHMKQHDFFKSAMPEGYVQERTIFFKDDGNYKTRAEVKFEGDTLVNRIELKGIDFKEDGNILGHKLEYNYNSHNVYIMADKQKNGIKVNFKIRHNIEDGSVQLADHYQQNTPIGDGPVLLPDNHYLSTQSALSKDPNEKRDHMVLLEFVTAAGITLGMDELYK

The base sequence is as follows:

atggtgagcaagggcgaggagctgttcaccggggtggtgcccatcctggtcgagctggacggcgacgtaaacggccacaagttcagcgtgtccggcgagggcgagggcgatgccacctacggcaagctgaccctgaagttcatctgcaccaccggcaagctgcccgtgccctggcccaccctcgtgaccaccctgacctacggcgtgcagtgcttcagccgctaccccgaccacatgaagcagcacgacttcttcaagtccgccatgcccgaaggctacgtccaggagcgcaccatcttcttcaaggacgacggcaactacaagacccgcgccgaggtgaagttcgagggcgacaccctggtgaaccgcatcgagctgaagggcatcgacttcaaggaggacggcaacatcctggggcacaagctggagtacaactacaacagccacaacgtctatatcatggccgacaagcagaagaacggcatcaaggtgaacttcaagatccgccacaacatcgaggacggcagcgtgcagctcgccgaccactaccagcagaacacccccatcggcgacggccccgtgctgctgcccgacaaccactacctgagcacccagtccgccctgagcaaagaccccaacgagaagcgcgatcacatggtcctgctggagttcgtgaccgccgccgggatcactctcggcatggacgagctgtacaag

a DNAworks online tool (http:// helix web. nih. gov/DNAworks /) is used for designing a corresponding coding DNA sequence to obtain a gene of the fusion protein of the hICOS and the EGFP and a gene of the hICOS-EGFP. The DNA fragment is obtained by artificial synthesis. The synthesized gene sequence is subcloned into a commercial vector pcDNA4/myc-HisA (Invitrogen, V863-20) through HindIII and EcoRI double enzyme digestion of Fermentas company, and the accuracy of the constructed plasmid is verified by sequencing to obtain recombinant plasmid DNA, namely: pcDNA4-hICOS-Fc and pcDNA 4-hICOS-EGFP.

The relevant EGFP recombinant plasmids were transfected into HEK293(ATCC, CRL-1573. TM.) cells and the expression of hICOS was confirmed 48h after transfection by fluorescence activated Signal sorting (FACS).

pcDNA4-hICOS-Fc was transiently transfected into HEK293 cells for protein production. Diluting the recombinant expression plasmid with Freestyle293 medium and adding PEI (polyethyleneimine) solution required for transformation, adding each group of plasmid/PEI mixture into the cell suspension respectively, and placing at 37 ℃ and 10% CO₂Culturing at 90 rpm; after culturing for 5-6 days, transient expression culture supernatant is collected and subjected to primary purification by a protein affinity chromatography to obtain a hICOS-Fc protein sample which is used in each example below. The obtained protein sample is subjected to primary detection by SDS-PAGE, and a target band can be clearly seen.

Example 2: screening anti-ICOS antibody from yeast display library, cloning and expressing

The yeast display technology is adopted to screen the whole human antibody of the needle selection to the human ICOS. Construction of scFV yeast display library by cloning VH and VL genes in IgM and IgG cDNAs from PBMCs of 50 healthy humans (the linker sequence between VH and VL is GILGSGGGGSGGGGSGGGGS linker peptide, the library content is 5X 10⁸. Recovering the yeast library with 10 times of library capacity, inducing yeast surface expression antibodies, enriching twice by using 100nM biotinylated hICOS-Fc antigen in a magnetic bead sorting mode, and then enriching twice by using biotinylated hICOS-Fc as a flow sorting mode. The resulting yeast was plated and single clones were picked. After amplification and inducible expression, the monoclonal yeast was analyzed by biotinylated hICOS-Fc staining to determine positive yeast. Yeast clones confirmed by FACS were subjected to yeast cloningColony PCR and sequencing, wherein PCR primers are as follows:

sequence-F：CGTAGAATCGAGACCGAGGAGA；

sequence-R：CTGGTGGTGGTGGTTCTGCTAGC；

the sequencing primer is sequence-R. And after a sequencing result is obtained, the sequences are compared and analyzed by using BioEdit software.

The scFv gene of the single-chain antibody obtained above and the human IgG1-Fc gene were fused and cloned into a commercial vector pcDNA4/myc-HisA by means of double digestion with HindIII and EcoRI from Fermentas corporation, and cloning and plasmid extraction were carried out according to standard procedures for molecular cloning. The extracted plasmid was transiently expressed in HEK293 cells and purified by protein a column. The amino acid sequence of the anti-hICOSscFv antibody is shown as SEQ ID NO: 8 (VH-Linker-VL, CDR in the wavy line portion and Linker in the underline):

the base sequence is shown as SEQ ID NO: 9 is as follows:

caggtccagctggtgcagtctggggctgaagtggagaagcctggggcctcagtgaaggtttcctgtaaggcttctggataccccttcactggctatgctctgcattgggtgcgccaggcccccggacaaaggcttgagtggatgggatggatcacccctggcaatggaaacacaaaatattcacagaagttccagggccgagtcacctttaccagggacacatccgcgagcacagcctacatggagttgagccccctgagacctgaagacacggctgtgtattactgtgcgagagcgctgcgggcatattgtactggtaccaactgctttgggggggcctttgattcctggggccagggaaccctggtcaccgtctcctcaggaattctaggatccggtggcggtggcagcggcggtggtggttccggaggcggcggttctcagcctgtgctgactcaatcaccctcggtgtcagtggccccaggacagacggccaagattacctgtggaggaaacaatattggaagtaaaagtgtgcactggtatcaacagaggccaggccaggcccctgtggtggtcgtctatgatgatagcgaccggccctcagggatccctgagcgattctctggctccaactctgagaacacggccacccttaccatcagcagggtcgaagccggggatgaggccgactattattgtcaggtgtgggatagtagtagtcatcagggagtgttcggaggaggcacccagctgaccgtcctc

example 3: characterization of anti-ICOS antibodies (characterization by binding to ICOS-FACS method)

Taking hICOS-EGFP cells, suspending the hICOS-EGFP cells in 0.5% PBS-BSABuffer, adding 2 mu g of anti-hICOS scFv antibody after purification, setting a relevant control at the same time, and setting a negative control as 2 mu g of hIgG1 protein. The secondary antibody is anti-hIg-PE of eBioscience. And detecting by a flow cytometer after dyeing. Antibodies that bind to the cell surface hICOS antigen were identified in this manner. As shown in FIG. 1, anti-ICOS19-2-1 could bind to cell surface hICOS, while the negative control was not able to bind to cell surface hICOS.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Sequence listing

<110> Suzhou Dingfu target biotech Co., Ltd

<120> ICOS antibody, gene, vector, host cell and ICOS antagonist

<130> MP1917791

<160> 9

<170> SIPOSequenceListing 1.0

<210> 1

<211> 5

<212> PRT

<213> Artificial Sequence (Artificial Sequence)

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Gly Tyr Ala Leu His

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<210> 2

<211> 17

<212> PRT

<213> Artificial Sequence (Artificial Sequence)

<400> 2

Trp Ile Thr Pro Gly Asn Gly Asn Thr Lys Tyr Ser Gln Lys Phe Gln

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Gly

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<212> PRT

<213> Artificial Sequence (Artificial Sequence)

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Ala Leu Arg Ala Tyr Cys Thr Gly Thr Asn Cys Phe Gly Gly Ala Phe

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Asp Ser

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<211> 11

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<213> Artificial Sequence (Artificial Sequence)

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Gly Gly Asn Asn Ile Gly Ser Lys Ser Val His

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<212> PRT

<213> Artificial Sequence (Artificial Sequence)

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Asp Asp Ser Asp Arg Pro Ser

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<213> Artificial Sequence (Artificial Sequence)

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Gln Val Trp Asp Ser Ser Ser His Gln Gly Val

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<212> PRT

<213> Artificial Sequence (Artificial Sequence)

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Gly Ile Leu Gly Ser Gly Gly Gly Gly Ser Gly Gly Gly Gly Ser Gly

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Gly Gly Gly Ser

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<210> 8

<211> 255

<212> PRT

<213> Artificial Sequence (Artificial Sequence)

<400> 8

Gln Val Gln Leu Val Gln Ser Gly Ala Glu Val Glu Lys Pro Gly Ala

1 5 10 15

Ser Val Lys Val Ser Cys Lys Ala Ser Gly Tyr Pro Phe Thr Gly Tyr

20 25 30

Ala Leu His Trp Val Arg Gln Ala Pro Gly Gln Arg Leu Glu Trp Met

35 40 45

Gly Trp Ile Thr Pro Gly Asn Gly Asn Thr Lys Tyr Ser Gln Lys Phe

50 55 60

Gln Gly Arg Val Thr Phe Thr Arg Asp Thr Ser Ala Ser Thr Ala Tyr

65 70 75 80

Met Glu Leu Ser Pro Leu Arg Pro Glu Asp Thr Ala Val Tyr Tyr Cys

85 90 95

Ala Arg Ala Leu Arg Ala Tyr Cys Thr Gly Thr Asn Cys Phe Gly Gly

100 105 110

Ala Phe Asp Ser Trp Gly Gln Gly Thr Leu Val Thr Val Ser Ser Gly

115 120 125

Ile Leu Gly Ser Gly Gly Gly Gly Ser Gly Gly Gly Gly Ser Gly Gly

130 135 140

Gly Gly Ser Gln Pro Val Leu Thr Gln Ser Pro Ser Val Ser Val Ala

145 150 155 160

Pro Gly Gln Thr Ala Lys Ile Thr Cys Gly Gly Asn Asn Ile Gly Ser

165 170 175

Lys Ser Val His Trp Tyr Gln Gln Arg Pro Gly Gln Ala Pro Val Val

180 185 190

Val Val Tyr Asp Asp Ser Asp Arg Pro Ser Gly Ile Pro Glu Arg Phe

195 200 205

Ser Gly Ser Asn Ser Glu Asn Thr Ala Thr Leu Thr Ile Ser Arg Val

210 215 220

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

225 230 235 240

Ser His Gln Gly Val Phe Gly Gly Gly Thr Gln Leu Thr Val Leu

245 250 255

<210> 9

<211> 765

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<213> Artificial Sequence (Artificial Sequence)

<400> 9

caggtccagc tggtgcagtc tggggctgaa gtggagaagc ctggggcctc agtgaaggtt 60

tcctgtaagg cttctggata ccccttcact ggctatgctc tgcattgggt gcgccaggcc 120

cccggacaaa ggcttgagtg gatgggatgg atcacccctg gcaatggaaa cacaaaatat 180

tcacagaagt tccagggccg agtcaccttt accagggaca catccgcgag cacagcctac 240

atggagttga gccccctgag acctgaagac acggctgtgt attactgtgc gagagcgctg 300

cgggcatatt gtactggtac caactgcttt gggggggcct ttgattcctg gggccaggga 360

accctggtca ccgtctcctc aggaattcta ggatccggtg gcggtggcag cggcggtggt 420

ggttccggag gcggcggttc tcagcctgtg ctgactcaat caccctcggt gtcagtggcc 480

ccaggacaga cggccaagat tacctgtgga ggaaacaata ttggaagtaa aagtgtgcac 540

tggtatcaac agaggccagg ccaggcccct gtggtggtcg tctatgatga tagcgaccgg 600

ccctcaggga tccctgagcg attctctggc tccaactctg agaacacggc cacccttacc 660

atcagcaggg tcgaagccgg ggatgaggcc gactattatt gtcaggtgtg ggatagtagt 720

agtcatcagg gagtgttcgg aggaggcacc cagctgaccg tcctc 765

Claims

1. An ICOS antibody, wherein the heavy chain of the ICOS antibody comprises SEQ ID NO: 1, CDR1 of the sequence shown in SEQ ID NO: 2, CDR2 of the sequence shown in SEQ ID NO: 3 CDR3 of the sequence shown in seq id no;

2. The ICOS antibody of claim 1, wherein the heavy chain and the light chain of said ICOS antibody are linked by a linker having an amino acid sequence as set forth in SEQ ID NO: shown at 7.

3. An ICOS antibody, wherein the amino acid sequence of said ICOS antibody is as set forth in SEQ ID NO: shown in fig. 8.

4. The ICOS antibody according to claim 3, wherein said ICOS antibody is a humanized antibody.

5. A gene encoding the ICOS antibody according to claim 3 or 4, characterized in that it has a base sequence as set forth in SEQ ID NO: shown at 9.

6. A vector comprising the gene of claim 5.

7. The vector of claim 6, wherein the plasmid used in the vector is pcDNA 4/myc-HisA.

8. A host cell comprising the vector of claim 6.

9. The host cell of claim 8, wherein the host cell is a HEK293 cell.

10. An ICOS antagonist comprising the ICOS antibody of any one of claims 1 to 4.