Anti-SAA antibodies, reagents and kits for detecting SAA

Abstract

The present invention discloses an anti-SAA antibody or a reagent and kit for detecting SAA, and relates to the field of antibodies. The anti-SAA antibody disclosed in the present invention comprises a heavy chain complementary determining region and a light chain complementary determining region, and the antibody provides an important raw material source for the detection of SAA and has good activity.

Description

Technical Field

[0001] The present invention relates to the field of antibody technology, and in particular to an anti-SAA antibody, a reagent and a kit for detecting SAA. Background Art

[0002] Serum amyloid A (SAA) is a 104-amino acid polypeptide with a molecular weight of approximately 12,000 to 14,000 in its native state. It is an acute phase protein and a heterogeneous class of proteins within the apolipoprotein family. During the acute phase, SAA is synthesized in the liver by activated macrophages and fibroblasts in response to IL-1, IL-6, and TNF, reaching concentrations 100-1,000 times its initial level. However, its half-life is extremely short, at approximately 50 minutes. It also significantly increases in the early stages of bacterial and viral infections and rapidly in response to stressful conditions such as trauma and burns.

[0003] SAA is elevated in both viral and bacterial infections, whereas CRP barely increases or only minimally increases in viral infections. SAA is more sensitive than CRP to mild inflammatory stimuli, exceeding the upper limit of the reference range earlier than CRP, increasing earlier, and decreasing more rapidly and with greater amplitude during recovery. Therefore, SAA is a relatively sensitive marker in patients with viral infections and non-invasive or early invasive bacterial infections with normal CRP. In the early stages of pediatric infectious illness, the distinction between bacterial and viral infections can be challenging due to ambiguous signs and symptoms. Therefore, rapid and early differentiation between bacterial and viral infections in children is crucial for timely and effective treatment and prevention of various complications. While CRP lacks sensitivity for viral infections, SAA can be elevated in the early stages of both bacterial and viral infections. Combined testing of SAA and CRP can improve the efficiency of early diagnosis of viral infections and provide valuable information for differentiating viral from bacterial infections and selecting treatment options. Furthermore, the SAA / CRP ratio correlates with the severity of pediatric infectious illnesses, making monitoring SAA / CRP more valuable than testing SAA or CRP alone. At the same time, studies have shown that SAA levels in patients with many tumors, such as liver cancer, lung cancer, breast cancer, prostate cancer, and endometrial cancer, are elevated to varying degrees. SAA levels are significantly correlated with the activity, malignancy, and metastasis of the tumor. The increase in SAA in the metastasis stage of malignant tumors usually shows higher values ​​than in the stable stage of the tumor.

[0004] Currently, the primary method for detecting SAA is fluorescence immunochromatography, an immunological method based on the specific reaction between antibodies and antigens, which utilizes fluorescence to amplify and display the detected signal. Similar immunological detection methods include radioimmunoassay, enzyme-linked immunosorbent assay, chemiluminescence, and latex turbidimetry. All of these immunological detection methods require monoclonal antibodies specific for SAA.

[0005] Therefore, there is a strong need in the art for antibodies that can effectively bind to and detect SAA. Summary of the Invention

[0006] The present application provides an antibody or a functional fragment thereof, which provides an important source of raw materials for the detection of SAA and has good activity.

[0007] In order to achieve the above-mentioned object, according to one aspect of the present invention, an antibody or a functional fragment thereof is provided, wherein the antibody or the functional fragment thereof comprises three complementarity determining regions of a heavy chain variable region having the amino acid sequence of SEQ ID NO: 17 and three complementarity determining regions of a light chain variable region having any one of the amino acid sequences of SEQ ID NO: 18, 19, and 20.

[0008] In order to achieve the above object, according to a second aspect of the present invention, an antibody or a functional fragment thereof is provided, wherein the antibody or the functional fragment thereof comprises the following complementarity determining regions:

[0009] HCDR1 comprising or consisting of the amino acid sequence shown in SEQ ID NO: 1;

[0010] HCDR2 comprising or consisting of the amino acid sequence shown in SEQ ID NO: 2;

[0011] HCDR3 comprising or consisting of the amino acid sequence shown in SEQ ID NO: 3;

[0012] LCDR1, which comprises or consists of the amino acid sequence shown in SEQ ID NO:4;

[0013] LCDR2, which comprises or consists of the amino acid sequence shown in SEQ ID NO: 5;

[0014] LCDR3 comprises or consists of the amino acid sequence shown in SEQ ID NO: 6.

[0015] In order to achieve the above-mentioned object, according to the third aspect of the present invention, an antibody or a functional fragment thereof is provided, comprising a heavy chain variable region and / or a light chain variable region, wherein the amino acid sequence of the heavy chain variable region is shown in SEQ ID NO: 17; and the amino acid sequence of the light chain variable region is shown in any one of SEQ ID NOs: 18, 19, and 20.

[0016] In order to achieve the above-mentioned object, according to the fourth aspect of the present invention, an antibody or a functional fragment thereof is provided, comprising a heavy chain and / or a light chain, wherein the amino acid sequence of the heavy chain is shown in SEQ ID NO: 21; the amino acid sequence of the light chain is shown in any one of SEQ ID NOs: 22, 23, and 24.

[0017] In order to achieve the above object, according to the fifth aspect of the present invention, an antibody conjugate is provided, wherein the antibody conjugate comprises the above antibody or a functional fragment thereof.

[0018] In order to achieve the above object, according to the sixth aspect of the present invention, a reagent or kit is provided, wherein the reagent or kit comprises the above-mentioned antibody or its functional fragment or the above-mentioned antibody conjugate.

[0019] To achieve the above-mentioned object, according to a seventh aspect of the present invention, a method for detecting SAA is provided, comprising: a) contacting the above-mentioned antibody or its functional fragment, antibody conjugate, or reagent or kit with SAA in a sample to be detected under conditions sufficient for an antibody / antigen binding reaction to occur, to form an immune complex; and b) detecting the presence of the immune complex, wherein the presence of the complex indicates the presence of the antigen in the test sample.

[0020] In order to achieve the above object, according to the eighth aspect of the present invention, a nucleic acid is provided, which encodes the above antibody or a functional fragment thereof.

[0021] In order to achieve the above object, according to the ninth aspect of the present invention, a vector is provided, wherein the vector comprises the above nucleic acid.

[0022] To achieve the above object, according to the tenth aspect of the present invention, a cell is provided, wherein the cell comprises the above nucleic acid, vector or expresses the above antibody or a functional fragment thereof.

[0023] In order to achieve the above object, according to the eleventh aspect of the present invention, a method for preparing the above antibody or a functional fragment thereof is provided, which comprises culturing the above cell.

[0024] In order to achieve the above-mentioned object, according to the twelfth aspect of the present invention, there is provided a use of the above-mentioned antibody or its functional fragment, antibody conjugate, reagent or kit in detecting or preparing a SAA product. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 These are the results of reducing SDS-PAGE of Anti-SAA 9C3Rmb1 to Anti-SAA 9C3 Rmb3. DETAILED DESCRIPTION

[0027] In the first aspect, an embodiment of the present invention provides an antibody or a functional fragment thereof, wherein the antibody or the functional fragment thereof comprises three complementarity determining regions of a heavy chain variable region having the amino acid sequence of SEQ ID NO: 17 and three complementarity determining regions of a light chain variable region having any one of the amino acid sequences of SEQ ID NO: 18, 19, and 20.

[0028] It should be noted that HCDR1, HCDR2 and HCDR3 are amino acid sequences consistent with HCDR1, HCDR2 and HCDR3 of the same heavy chain variable region defined in the antibody or its functional fragment described in the first aspect, and LCDR1, LCDR2 and LCDR3 are amino acid sequences consistent with LCDR1, LCDR2 and LCDR3 of the same light chain variable region defined in the antibody or its functional fragment described in the first aspect.

[0029] For example, the HCDR1, HCDR2, and HCDR3 have amino acid sequences consistent with those of HCDR1, HCDR2, and HCDR3 in the heavy chain variable region shown in SEQ ID NO: 17; and the LCDR1, LCDR2, and LCDR3 have amino acid sequences consistent with those of LCDR1, LCDR2, and LCDR3 in the light chain variable region shown in SEQ ID NO: 18.

[0030] In the present invention, the term "antibody" is used in the broadest sense and may include full-length monoclonal antibodies, bispecific or multispecific antibodies, and chimeric antibodies, so long as they exhibit the desired biological activity.

[0031] As used herein, the terms "complementarity determining region," "CDR," or "CDRs" refer to the hypervariable regions of the heavy and light chains of immunoglobulins, and include one or more, or even all, of the amino acid residues that contribute substantially to the binding of an antibody or antigen-binding fragment to its recognized antigen or epitope. In specific embodiments of the present invention, CDRs refer to the hypervariable regions of the heavy and light chains of the antibody.

[0032] In the present invention, the heavy chain complementarity determining region is represented by HCDR, which includes HCDR1, HCDR2 and HCDR3; the light chain complementarity determining region is represented by LCDR, which includes LCDR1, LCDR2 and LCDR3.

[0033] Methods for defining CDRs are well known in the art, including the Kabat definition, the Chothia definition, the IMGT definition, the Contact definition, and the AbM definition. As used herein, the "Kabat definition" refers to the definition system described by Kabat et al., U.S. Patent No. 200200201154, "Sequence of Proteins of Immunological Interest" (1983). The "Chothia definition" refers to the definition system described by Chothia et al., J Mol Biol 196: 901-917 (1987). Other CDR definition methods may not strictly follow one of the above schemes, but will still overlap with at least a portion of the CDR region defined by Kabat, although they may be shortened or lengthened based on predictions or experimental results of specific residues or residue groups. Exemplary defined CDRs are listed in Table 1 below, and the definitions in different literature vary slightly. Given the variable region amino acid sequence of an antibody, a person skilled in the art can routinely determine which residues comprise a specific CDR. It should be noted that CDRs defined by other methods other than those in Table 1 also fall within the scope of protection of the present disclosure.

[0034] Table 1: CDR Definition 1

[0035]

[0036]

[0037] 1The numbering of all CDR definitions in Table 1 is based on the Kabat numbering system (see below), with amino acid numbers on the heavy chain represented by "H+number" and amino acid numbers on the light chain represented by "L+number." One of ordinary skill in the art can unambiguously assign this Kabat numbering system to any variable region sequence without relying on any experimental data other than the sequence itself. As used herein, "Kabat numbering" refers to the numbering system described in Kabat et al., U.S. Pat. of Health and Human Services, "Sequence of Proteins of Immunological Interest" (1983).

[0038] 2 "AbM" as used in Table 1 with a lowercase "b" refers to CDRs defined by Oxford Molecular's "AbM" antibody modeling software.

[0039] 3 If both H35A and H35B are absent, CDR-H1 ends at position 35; if only H35A is present, CDR-H1 ends at position 35A; if both H35A and H35B are present, CDR-H1 ends at position 35B.

[0040] 4 If both H35A and H35B are absent, CDR-H1 ends at position 32; if only H35A is present, CDR-H1 ends at position 33; if both H35A and H35B are present, CDR-H1 ends at position 34.

[0041] 5 If both H35A and H35B are absent, CDR-H1 ends at position 33; if only H35A is present, CDR-H1 ends at position 34; if both H35A and H35B are present, CDR-H1 ends at position 35.

[0042] According to an embodiment of the present invention, the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 or LCDR3 is defined by any one of the Kabat, Chothia, IMGT, AbM or Contact systems or a combination of multiple systems.

[0043] In some optional embodiments of the present invention, the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 are defined by the Kabat system.

[0044] In some optional embodiments of the present invention, the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 are defined by the Chothia system.

[0045] In some optional embodiments of the present invention, the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 are defined by an IMGT system.

[0046] In some optional embodiments of the present invention, the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 are defined by the AbM system.

[0047] In some optional embodiments of the present invention, the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 are defined by a Contact system.

[0048] In some optional embodiments of the present invention, the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 are defined by a combination of Kabat, Chothia, IMGT, AbM or Contact systems.

[0049] According to an embodiment of the present invention, the Kabat numbering positions corresponding to the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 or LCDR3 defined by the Kabat, Chothia, AbM or IMGT systems are as follows:

[0050]

[0051] According to an embodiment of the present invention, the HCDRs and LCDRs are defined by the Kabat system.

[0052] In a second aspect, an embodiment of the present invention provides an antibody or a functional fragment thereof, wherein the antibody or the functional fragment thereof comprises the following complementarity determining regions:

[0053] HCDR1 comprises or consists of the amino acid sequence shown in SEQ ID NO: 1.

[0054] HCDR2 comprises or consists of the amino acid sequence shown in SEQ ID NO: 2.

[0055] HCDR3 comprises or consists of the amino acid sequence shown in SEQ ID NO: 3.

[0056] LCDR1 comprises or consists of the amino acid sequence shown in SEQ ID NO: 4.

[0057] LCDR2 comprises or consists of the amino acid sequence shown in SEQ ID NO: 5.

[0058] LCDR3 comprises or consists of the amino acid sequence shown in SEQ ID NO: 6.

[0059] In the present invention, the "framework region" or "FR" region includes the heavy chain framework region and the light chain framework region, and refers to the region of the antibody heavy chain variable region and the light chain variable region excluding CDR; wherein the heavy chain framework region can be further subdivided into adjacent regions separated by CDR, including HFR1, HFR2, HFR3 and HFR4 framework regions; the light chain framework region can be further subdivided into adjacent regions separated by CDR, including LFR1, LFR2, LFR3 and LFR4 framework regions.

[0060] In the present invention, the heavy chain variable region is obtained by arranging and connecting the following numbered CDRs and FRs in the following combinations: HFR1-HCDR1-HFR2-HCDR2-HFR3-HCDR3-HFR4; the light chain variable region is obtained by arranging and connecting the following numbered CDRs and FRs in the following combinations: LFR1-LCDR1-LFR2-LCDR2-LFR3-LCDR3-LFR4.

[0061] In an optional embodiment, the antibody or functional fragment thereof further has at least one of HFR1, HFR2, HFR3, HFR4, LFR1, LFR2, LFR3 and LFR4;

[0062] The HFR1 comprises / is as SEQ ID NO: 7 or an amino acid sequence having at least 80% identity thereto;

[0063] The HFR2 comprises / is as SEQ ID NO: 8 or an amino acid sequence having at least 80% identity thereto;

[0064] The HFR3 comprises / is SEQ ID NO: 9 or an amino acid sequence having at least 80% identity thereto;

[0065] The HFR4 comprises / is as SEQ ID NO: 10 or an amino acid sequence having at least 80% identity thereto;

[0066] The LFR1 comprises / is SEQ ID NO: 11 or an amino acid sequence having at least 80% identity thereto;

[0067] The LFR2 comprises / is SEQ ID NO: 12 or an amino acid sequence having at least 80% identity thereto;

[0068] The LFR3 comprises / is SEQ ID NO: 13 or an amino acid sequence having at least 80% identity thereto;

[0069] The LFR4 comprises / is SEQ ID NO: 14 or an amino acid sequence having at least 80% identity thereto;

[0070] It should be noted that, in other embodiments, the amino acid sequences of the framework regions of the antibodies or functional fragments thereof provided by the present invention may be at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the corresponding framework regions (SEQ ID NO: 7, 8, 9, 10, 11, 12, 13 or 14).

[0071] In an optional embodiment, the LFR1 includes / is represented by the amino acid sequence shown in SEQ ID NO: 11 or 25.

[0072] In an optional embodiment, the LFR3 comprises / is represented by the amino acid sequence shown in SEQ ID NO: 13 or 26.

[0073] In a third aspect, an embodiment of the present invention provides an antibody or a functional fragment thereof, comprising a heavy chain variable region and / or a light chain variable region, wherein the amino acid sequence of the heavy chain variable region is shown in SEQ ID NO: 17, and the amino acid sequence of the light chain variable region is shown in any one of SEQ ID NOs: 18, 19, and 20.

[0074] In an alternative embodiment, the antibody or functional fragment thereof further comprises a constant region.

[0075] In alternative embodiments, the constant region comprises a heavy chain constant region and / or a light chain constant region.

[0076] In an optional embodiment, the heavy chain constant region is selected from any one of the heavy chain constant regions of IgG, IgA, IgM, IgE, and IgD, or a combination of multiple constant region segments.

[0077] In an alternative embodiment, the heavy chain constant region includes CH1 of IgG, a hinge region of IgG, CH2 of IgM, CH3 of IgM and / or CH4 of IgM.

[0078] In an alternative embodiment, the IgG is selected from IgG1, IgG2, IgG3 or IgG4.

[0079] In an alternative embodiment, the light chain constant region is selected from a kappa-type or lambda-type light chain constant region.

[0080] In an alternative embodiment, the species origin of the constant region is cow, horse, dairy cow, pig, sheep, rat, mouse, dog, cat, rabbit, donkey, deer, mink, chicken, duck, goose, turkey, fighting cock or human.

[0081] In an alternative embodiment, the species origin of the constant region is mouse.

[0082] In an optional embodiment, the heavy chain constant region sequence (CH) is shown as SEQ ID NO:15, and the light chain constant region (CL) sequence is shown as SEQ ID NO:16.

[0083] It should be noted that, in other embodiments, the constant region sequence may be at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the above-mentioned constant region (SEQ ID NO: 15 or 16).

[0084] In an optional embodiment, the functional fragment is selected from any one of F(ab')2, Fab', Fab, Fv and scFv of the antibody.

[0085] The functional fragments of the above-mentioned antibodies generally have the same binding specificity as the antibody from which they are derived. Based on the disclosure herein, those skilled in the art will readily appreciate that the functional fragments of the above-mentioned antibodies can be obtained by, for example, enzymatic digestion (including pepsin or papain) and / or by chemical reduction cleavage of disulfide bonds. Based on the structure of the intact antibody disclosed herein, those skilled in the art can readily obtain the above-mentioned functional fragments.

[0086] Functional fragments of the above antibodies can also be synthesized by recombinant genetic techniques known to those skilled in the art or by, for example, an automatic peptide synthesizer, such as those sold by Applied BioSystems.

[0087] In a fourth aspect, the present invention provides an antibody or a functional fragment thereof, comprising a heavy chain and / or a light chain, wherein the amino acid sequence of the heavy chain is shown in SEQ ID NO: 21, and the amino acid sequence of the light chain is shown in any one of SEQ ID NOs: 22, 23, and 24.

[0088] In a fifth aspect, the present invention provides an antibody conjugate comprising the above-mentioned antibody or a functional fragment thereof.

[0089] In an optional embodiment, the above-mentioned antibody conjugate further comprises biotin or a biotin derivative coupled to the antibody or a functional fragment thereof.

[0090] In an optional embodiment, the antibody conjugate further comprises a label coupled to the antibody or a functional fragment thereof.

[0091] In an optional embodiment, the above-mentioned marker refers to a class of substances with properties that can be directly observed by the naked eye or detected or detected by an instrument, such as luminescence, color development, radioactivity, etc., through which qualitative or quantitative detection of the corresponding target can be achieved.

[0092] In an alternative embodiment, the label includes but is not limited to fluorescent dyes, enzymes, radioisotopes, chemiluminescent reagents and nanoparticle labels.

[0093] In actual use, those skilled in the art can select a suitable marker according to the detection conditions or actual needs. No matter which marker is used, it falls within the scope of protection of the present invention.

[0094] In an optional embodiment, the fluorescent dyes include but are not limited to fluorescein dyes and their derivatives (for example, including but not limited to fluorescein isothiocyanate (FITC), hydroxyfluorescein (FAM), tetrachlorofluorescein (TET), etc. or their analogs), rhodamine dyes and their derivatives (for example, including but not limited to red rhodamine (RBITC), tetramethylrhodamine (TAMRA), rhodamine B (TRITC), etc. or their analogs), Cy series dyes and their derivatives (for example, including but not limited to Cy2, Cy3, Cy3B, Cy3.5, C y5, Cy5.5, Cy3, etc. or their analogs), Alexa series dyes and their derivatives (for example, including but not limited to AlexaFluor350, 405, 430, 488, 532, 546, 555, 568, 594, 610, 33, 647, 680, 700, 750, etc. or their analogs) and protein dyes and their derivatives (for example, including but not limited to phycoerythrin (PE), phycocyanin (PC), allophycocyanin (APC), peridinin-chlorophyll protein (preCP), etc.).

[0095] In alternative embodiments, the enzyme includes, but is not limited to, horseradish peroxidase, alkaline phosphatase, β-galactosidase, glucose oxidase, carbonic anhydrase, acetylcholinesterase, and glucose-6-phosphate deoxidase.

[0096] In an optional embodiment, the radioactive isotopes include but are not limited to 212Bi, 131I, 111In, 90Y, 186Re, 211At, 125I, 188Re, 153Sm, 213Bi, 32P, 94mTc, 99mTc, 203Pb, 67Ga, 68Ga, 43Sc, 47Sc, 110mIn, 97Ru, 62Cu, 64Cu, 67Cu, 68Cu, 86Y, 88Y, 121Sn, 161Tb, 166Ho, 105Rh, 177Lu, 172Lu and 18F.

[0097] In an optional embodiment, the chemiluminescent reagent includes but is not limited to luminol and its derivatives, lucigenin, crustacean fluorescein and its derivatives, ruthenium bipyridine and its derivatives, acridinium esters and their derivatives, dioxetanes and their derivatives, lophanes and their derivatives, and peroxalates and their derivatives.

[0098] In an optional embodiment, the nanoparticle markers include but are not limited to nanoparticles, colloids, organic nanoparticles, magnetic nanoparticles, quantum dot nanoparticles and rare earth complex nanoparticles.

[0099] In alternative embodiments, the colloid includes, but is not limited to, colloidal metals, disperse dyes, dye-labeled microspheres, and latex.

[0100] In an alternative embodiment, the colloidal metal includes, but is not limited to, colloidal gold, colloidal silver, and colloidal selenium.

[0101] In an optional embodiment, the above-mentioned antibody conjugate further comprises a solid phase carrier coupled to the antibody or its functional fragment.

[0102] In an alternative embodiment, the solid support is selected from microspheres, plates, and membranes.

[0103] In an optional embodiment, the solid phase carrier includes but is not limited to magnetic microspheres, plastic microspheres, plastic particles, microplates, glass, capillaries, nylon and nitrocellulose membranes.

[0104] In a sixth aspect, the present invention provides a reagent or a kit, which comprises the above-mentioned antibody or a functional fragment thereof or the above-mentioned antibody conjugate.

[0105] As previously mentioned, the antibodies or functional fragments thereof in some embodiments or examples of the present invention can effectively bind to SAA. Therefore, reagents or kits containing such SAA antibodies or functional fragments can effectively detect SAA qualitatively or quantitatively. The reagents or kits provided by the present invention can be used, for example, in immunoblotting, immunoprecipitation, and other assays that utilize the specific binding properties of SAA and its antibodies. As previously mentioned, the antibodies or functional fragments thereof in some embodiments or examples of the present invention have higher binding activity to SAA. Therefore, reagents or kits containing such antibodies or functional fragments have higher detection sensitivity or specificity.

[0106] In a seventh aspect, the present invention provides a method for detecting SAA, comprising: a) contacting the above-mentioned antibody or functional fragment thereof, antibody conjugate, reagent or kit with SAA in a sample to be tested under conditions sufficient for an antibody / antigen binding reaction to occur to form an immune complex; and b) detecting the presence of the immune complex, wherein the presence of the complex indicates the presence of the antigen in the test sample;

[0107] In an optional embodiment, the immune complex further comprises a second antibody, which binds to the antibody or a functional fragment thereof.

[0108] In an alternative embodiment, the immune complex further comprises a second antibody, which binds to SAA.

[0109] In an eighth aspect, the present invention provides a nucleic acid molecule encoding the above-mentioned antibody or a functional fragment thereof.

[0110] In a ninth aspect, the present invention provides a vector containing the above-mentioned nucleic acid molecule.

[0111] In a tenth aspect, the present invention provides a cell containing the above-mentioned vector.

[0112] In an eleventh aspect, the present invention provides a method for preparing an antibody or a functional fragment thereof, comprising: culturing the cell as described above.

[0113] In a twelfth aspect, the present invention provides use of the above-mentioned antibody or functional fragment thereof, antibody conjugate, or the above-mentioned reagent or kit in detecting SAA or preparing a product for detecting SAA.

[0114] Based on the amino acid sequence of the antibody or its functional fragment disclosed in the present invention, those skilled in the art can easily conceive of using genetic engineering technology or other technologies (chemical synthesis, recombinant expression) to prepare the antibody or its functional fragment. For example, the antibody or its functional fragment can be isolated and purified from the culture product of a recombinant cell that can recombinantly express the antibody or its functional fragment as described in any of the above items. This is easy to achieve for those skilled in the art. Based on this, no matter what technology is used to prepare the antibody or its functional fragment of the present invention, it falls within the scope of protection of the present invention.

[0115] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0116] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the preparations or unit doses herein, some methods and materials are now described. Unless otherwise indicated, the techniques employed or contemplated herein are standard methods. Materials, methods, and examples are illustrative and non-limiting only.

[0117] The practice of the present invention will employ, unless otherwise indicated, conventional techniques of cell biology, molecular biology (including recombinant techniques), microbiology, biochemistry, and immunology, which are within the capabilities of a person skilled in the art. The technique is fully explained in the literature, for example, in Molecular Cloning: A Laboratory Manual, 2nd ed. (Sambrook et al., 1989); Oligonucleotide Synthesis (MJ Gait, ed., 1984); Animal Cell Culture (RI Freshney, ed., 1987); Methods in Enzymology (Academic Press, Inc.); Handbook of Experimental Immunology (DM Weir and CC Blackwell, eds.); Gene Transfer Vectors for Mammalian Cells (JM Miller and MP Calos, eds., 1987); Current Protocols in Molecular Biology (FM Ausubel et al., eds., 1987); and PCR: The Polymerase Chain Reaction. Reaction" (Mullis et al., eds., 1994); and Current Protocols in Immunology (JE Coligan et al., eds., 1991), each of which is expressly incorporated herein by reference.

[0118] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0119] Example 1 Preparation of Anti-SAA 9C3 Monoclonal Antibody

[0120] In this example, restriction endonucleases and Prime Star DNA polymerase were purchased from Takara. MagExtractor-RNA extraction kit was purchased from TOYOBO. BD SMART TMThe RACE cDNA Amplification Kit was purchased from Takara. The pMD-18T vector was also purchased from Takara. The plasmid extraction kit was purchased from Tiangen. Primer synthesis and gene sequencing were performed by Invitrogen. The hybridoma cell line secreting the anti-SAA 9C3 monoclonal antibody was generated in our laboratory and revived for future use.

[0121] (1) Antibody gene preparation

[0122] mRNA was extracted from a hybridoma cell line secreting the Anti-SAA 9C3 monoclonal antibody. DNA products were obtained by RT-PCR. This product was PCR-polymerized with rTaq DNA polymerase and inserted into the pMD-18T vector. The cells were then transformed into DH5α competent cells. After colonies grew, the Heavy Chain and Light Chain gene clones were obtained, and four clones each were sent to a gene sequencing company for sequencing.

[0123] (2) Sequence analysis of the variable region gene of the Anti-SAA9C3 antibody

[0124] The gene sequences obtained by the above sequencing were placed in the Kabat antibody database for analysis, and VNTI11.5 software was used for analysis to determine that the genes amplified by the heavy chain and light chain primer pairs were correct. Among them, in the gene fragment amplified by the Light Chain, the VL gene sequence was 321 bp, preceded by a 57 bp leader peptide sequence; in the gene fragment amplified by the Heavy Chain primer pair, the VH gene sequence was 354 bp, belonging to the VH1 gene family, and preceded by a 57 bp leader peptide sequence.

[0125] (3) Construction of recombinant antibody expression plasmid

[0126] pcDNA TM 3.4 The vector is a recombinant antibody eukaryotic expression vector constructed by using the pMD-18T vector. Multiple cloning restriction sites such as HindIII, BamHI, and EcoRI have been introduced into the vector, and the vector is named pcDNA3.4A expression vector, hereinafter referred to as 3.4A expression vector. Based on the sequencing results of the antibody variable region genes in the pMD-18T vector, specific primers for the VL and VH genes of the antibody were designed, with HindIII and EcoRI restriction sites and protective bases at both ends, respectively. PCR amplification was used to amplify a 0.70 kb Light Chain gene fragment and a 1.38 kb Heavy Chain gene fragment.

[0127] The Heavy Chain and Light Chain gene fragments were digested with HindIII / EcoRI, and the 3.4A vector was digested with HindIII / EcoRI. After the fragments and vectors were purified and recovered, the Heavy Chain gene and Light Chain gene were respectively connected to the 3.4A expression vector to obtain the recombinant expression plasmids of Heavy Chain and Light Chain, respectively.

[0128] 2. Recombinant Antibody Production

[0129] Resuscitate HEK293 cells in advance and subculture them into 200 ml system to make the cell density reach 3-5×10 6 cells / ml cell density reaches the selected antibody concentration and cells, cell viability>95%; centrifuge and wash the cells, re-dissolve with culture medium, and adjust the cell density to 2.9×10 6 Cells were washed with 100 μg of culture medium and re-dissolved. This was also used as a cell diluent. Plasmid DNA and transfection reagent diluents were prepared separately using culture medium. The transfection reagent diluent was added to the plasmid DNA diluent, mixed, and allowed to stand at room temperature for 15 minutes. The mixture was slowly added to the cell diluent over 1 minute, mixed, and sampled. The viability of the cells after transfection was recorded and observed. The cells were cultured in a 35°C constant temperature incubator at 120 rpm and 8% CO2. After 13 days, the samples were collected by centrifugation. The supernatant was affinity purified using a protein A affinity chromatography column. 6 μg of the purified antibody was subjected to reducing SDS-PAGE. The electrophoresis pattern is shown in the figure. Two bands were shown after reducing SDS-PAGE, one with an Mr of 50 KD (heavy chain) and the other with an Mr of 28 KD (light chain).

[0130] The resulting antibody was named Anti-SAA9C3Rmb1. Anti-SAA9C3Rmb1 was mutated to obtain a mutant antibody. The sequences of the heavy chain (H) and light chain (L) of the above antibody are shown in the following table:

[0131] Table 2 Antibody sequences

[0132] Antibody name Heavy chain light chain Anti-SAA 9C3Rmb1 SEQ ID NO:21 SEQ ID NO:22 Anti-SAA 9C3Rmb2 SEQ ID NO:21 SEQ ID NO:23 Anti-SAA 9C3Rmb3 SEQ ID NO:21 SEQ ID NO:24

[0133] Example 2 Performance testing of antibodies

[0134] 1. Activity identification

[0135] SAA antigen (purchased from Yashraj Biotechnology Limited, catalog number FRSAA-61) was diluted to 3 μg / ml in coating buffer (main component: NaHCO₃) and 100 μL was added to each well at 4°C overnight. The next day, the wells were washed twice with wash buffer (main component: Na₂HPO₄ + NaCl) and patted dry. Blocking buffer (20% BSA + 80% PBS) was added at 120 μL per well and incubated at 37°C for 1 hour and patted dry. Diluted purified antibody and control antibody were added at 100 μL / well and incubated at 37°C for 30 minutes. The wells were washed five times with wash buffer and patted dry. Goat anti-mouse IgG-HRP was added at 100 μL per well and incubated at 37°C for 30 minutes. The wells were washed five times with wash buffer and patted dry. Chromogenic Buffer A (50 μL / well) and Chromogenic Buffer B (50 μL / well) were added for 10 minutes. Stop buffer (50 μL / well) was added and the OD values ​​were read on a microplate reader at 450 nm (reference: 630 nm).

[0136] Note: Solution A (main ingredients: citric acid + sodium acetate + acetanilide + urea peroxide); Solution B (main ingredients: citric acid + EDTA·2Na + TMB + concentrated HCL); Stop solution (EDTA·2Na + concentrated H2SO4)

[0137] Table 3 Activity data

[0138] Concentration (ng / ml) 500.00 250.00 125.00 62.50 31.25 0.00 comparison 1.502 0.971 0.578 0.332 0.113 0.018 Anti-SAA 9C3Rmb1 2.214 1.45 0.953 0.603 0.321 0.059 Anti-SAA 9C3Rmb2 2.219 1.394 0.961 0.584 0.345 0.088 Anti-SAA 9C3Rmb3 2.216 1.371 0.867 0.422 0.272 0.076

[0139] 2. Performance Evaluation

[0140] (1) Preparation of antibody latex microspheres

[0141] Add 100 μL of latex microspheres (JSR) to 390 μL of cross-linking solution (50 mM HEPES, pH 6.1) and mix thoroughly on a shaker to obtain a latex microsphere solution. Add 13 μL of EDAC solution to the latex microsphere solution and activate with shaking at 37°C for 1 hour. Add 50 μL of Anti-SAA 9C3RMb1, Anti-SAA 9C3RMb2, or Anti-SAA 9C3RMb3 to the latex microsphere solution to obtain antibody latex microsphere solution 1. By the same method, 50ul of another SAA antibody (from Feipeng Bio) was added to the latex microsphere liquid to prepare antibody latex microsphere liquid 2. The two antibody latex microsphere liquids were mixed and cross-linked at 37 degrees Celsius for 4 hours; 50ul of TW-20 solution was added and blocked at 37 degrees Celsius for 1 hour; the cross-linked liquid was added to a centrifuge tube, centrifuged, and the supernatant was discarded; 2ml of cleaning solution (50mM glycine + 0.1% NaN3, pH8.0) was added, vortexed, centrifuged again, and the supernatant was discarded; 5ml of latex microsphere suspension (50mM glycine + 0.1% BSA + 10% sucrose + 0.1% NaN3, pH8.0) was added and ultrasonically dispersed.

[0142] (2) Preparation of quality control products

[0143] The following quality control products with different concentrations were prepared using recombinant SAA antigen (purchased from Yashraj Biotechnology Limited, product number FRSAA-61): 10.0 mg / ml, 45.0 mg / ml, 90.0 mg / ml, 150.0 mg / ml, and 300 mg / ml.

[0144] The basic formula of diluent is: Tris buffer

[0145] (3) Computer test

[0146] Instrument: Fully automatic biochemical analyzer

[0147] Test procedure: Pipette 5µl of sample from the sample plate and 135µl of R1 into a cuvette, stir mechanically, and incubate at 37°C for 5 minutes. Add 15µl of R2 to the cuvette, stir mechanically, and incubate at 37°C for 8 minutes. Add 50µl of R3 to the cuvette, stir mechanically, and incubate at 37°C for 10 minutes. The instrument records the absorbance at 15 minutes and 30 seconds and 25 minutes and 30 seconds from the time the sample is added.

[0148] Table 4 Performance evaluation data

[0149]

[0150]

[0151] 3. Stability assessment

[0152] The above-mentioned antibody was placed at 4°C (refrigerator), -80°C (freezer), and 37°C (incubator) for 21 days. Samples were collected at 7, 14, and 21 days for observation, and the 21-day sample was tested for activity. The results showed that no significant changes in protein status were observed under all three test conditions for 21 days, and the activity did not decrease with increasing test temperature, indicating that the above-mentioned antibody is stable. Table 5 below shows the OD results of the enzyme immunoassay activity assay of the antibody Anti-SAA 9C3Rmb3 after 21 days of testing.

[0153] Table 5 Stability data

[0154] Sample concentration (ng / ml) 250.00 125.00 0.00 4℃, 21-day samples 1.081 0.681 0.048 -80℃, 21-day sample 1.028 0.532 0.099 37℃, 21-day samples 1.014 0.581 0.097

[0155] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

[0156] Some of the amino acid sequences involved in this application are shown in Table 6:

[0157]

[0158]

Claims

1. An anti-SAA antibody or a functional fragment thereof, characterized in that: The antibody or its functional fragment has three complementarity determining regions of the heavy chain variable region having the amino acid sequence of SEQ ID NO: 17 and three complementarity determining regions of the light chain variable region having the amino acid sequence of any one of SEQ ID NOs: 18, 19, and 20, and the complementarity determining regions of the variable regions are defined by any one of the Kabat, Chothia, IMGT or AbM systems.

2. An anti-SAA antibody or a functional fragment thereof, characterized in that: The antibody or its functional fragment comprises the following complementarity determining regions: The amino acid sequence of HCDR1 is shown in SEQ ID NO: 1; The amino acid sequence of HCDR2 is shown in SEQ ID NO: 2; The amino acid sequence of HCDR3 is shown in SEQ ID NO: 3; The amino acid sequence of LCDR1 is shown in SEQ ID NO:4; The amino acid sequence of LCDR2 is shown in SEQ ID NO:5; The amino acid sequence of LCDR3 is shown in SEQ ID NO:

6.

3. The antibody or functional fragment thereof according to claim 1 or 2, characterized in that The antibody or a functional fragment thereof further comprises HFR1, HFR2, HFR3, HFR4, LFR1, LFR2, LFR3 and LFR4.

4. The antibody or functional fragment thereof according to claim 3, characterized in that The HFR1 comprises SEQ ID NO: 7 or an amino acid sequence having at least 80% identity thereto; The HFR2 comprises SEQ ID NO: 8 or an amino acid sequence having at least 80% identity thereto; The HFR3 comprises SEQ ID NO: 9 or an amino acid sequence having at least 80% identity thereto; The HFR4 comprises SEQ ID NO: 10 or an amino acid sequence having at least 80% identity thereto; The LFR1 comprises SEQ ID NO: 11 or an amino acid sequence having at least 80% identity thereto; The LFR2 comprises SEQ ID NO: 12 or an amino acid sequence having at least 80% identity thereto; The LFR3 comprises SEQ ID NO: 13 or an amino acid sequence having at least 80% identity thereto; The LFR4 comprises SEQ ID NO: 14 or an amino acid sequence having at least 80% identity thereto.

5. An anti-SAA antibody or a functional fragment thereof, comprising a heavy chain variable region and a light chain variable region, characterized in that: The amino acid sequence of the heavy chain variable region is shown in SEQ ID NO: 17; the amino acid sequence of the light chain variable region is shown in any one of SEQ ID NOs: 18, 19, and 20.

6. The antibody or functional fragment thereof according to any one of claims 1 to 2, 4 to 5, wherein: The antibody or functional fragment thereof further comprises a constant region.

7. The antibody or functional fragment thereof according to claim 6, characterized in that The constant region includes a heavy chain constant region and a light chain constant region.

8. The antibody or functional fragment thereof according to claim 7, characterized in that The heavy chain constant region is selected from any one of the heavy chain constant regions of IgG, IgA, IgM, IgE, and IgD.

9. The antibody or functional fragment thereof according to claim 7, wherein The heavy chain constant region includes CH1 of IgG, a hinge region of IgG, CH2 of IgM, CH3 of IgM and / or CH4 of IgM.

10. The antibody or functional fragment thereof according to claim 6, characterized in that The species origin of the constant region is cow, horse, pig, sheep, goat, rat, mouse, dog, cat, rabbit, donkey, deer, mink, chicken, duck, goose or human.

11. The antibody or functional fragment thereof according to claim 6, characterized in that: The species origin of the constant region is mouse.

12. The antibody or functional fragment thereof according to claim 7, wherein The heavy chain constant region sequence is shown in SEQ ID NO: 15 or has at least 80% identity thereto; the light chain constant region sequence is shown in SEQ ID NO: 16 or has at least 80% identity thereto.

13. The antibody or functional fragment thereof according to any one of claims 1 to 2, 4 to 5, wherein: The functional fragment is selected from any one of F(ab')2, Fab', Fab, Fv and scFv of the antibody.

14. An anti-SAA antibody comprising a heavy chain and a light chain, characterized in that: The amino acid sequence of the heavy chain is shown in SEQ ID NO: 21; the amino acid sequence of the light chain is shown in any one of SEQ ID NOs: 22, 23, and 24.

15. An antibody conjugate, characterized in that The antibody conjugate consists of the antibody or functional fragment thereof according to any one of claims 1 to 13 or the antibody according to claim 14 and a biotin, fluorescent dye, enzyme, chemiluminescent reagent or nanoparticle marker coupled to the antibody or functional fragment thereof.

16. An antibody conjugate, characterized in that The antibody conjugate consists of the antibody or functional fragment thereof according to any one of claims 1 to 13 or the antibody according to claim 14 and a solid phase carrier coupled to the antibody or functional fragment thereof.

17. The conjugate according to claim 16, characterized in that The solid support is selected from microspheres, plates and membranes.

18. A reagent or kit, characterized in that The reagent or kit comprises the antibody or functional fragment thereof according to any one of claims 1 to 13, the antibody according to claim 14, or the antibody conjugate according to any one of claims 15 to 17.

19. Use of the antibody or functional fragment thereof according to any one of claims 1 to 13, the antibody according to claim 14, the antibody conjugate according to any one of claims 15 to 17, or the reagent or kit according to claim 18 in the preparation of a product for detecting SAA, characterized in that: include: a) contacting the antibody or functional fragment thereof according to any one of claims 1 to 13, the antibody according to claim 14, the antibody conjugate according to any one of claims 15 to 17, or the reagent or kit according to claim 18 with SAA in a sample to be detected under conditions sufficient for an antibody / antigen binding reaction to occur, to form an immune complex; and b) detecting the presence of the immune complex, wherein the presence of the complex indicates the presence of the antigen in the test sample.

20. The use according to claim 19, characterized in that The immune complex further comprises a second antibody that binds to the antibody or a functional fragment thereof.

21. The use according to claim 19, characterized in that The immune complex also includes a second antibody that binds to SAA.

22. A nucleic acid, characterized in that It encodes the antibody or functional fragment thereof according to any one of claims 1 to 13 or the antibody according to claim 14.

23. A carrier, characterized in that It contains the nucleic acid according to claim 22.

24. A cell, characterized in that It contains the nucleic acid according to claim 22 or the vector according to claim 23.

25. A method for preparing the antibody or functional fragment thereof according to any one of claims 1 to 13 or the antibody according to claim 14, characterized in that: It includes: Cultivate the cell of claim 24.

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