Disclosure of Invention
The invention aims to solve the technical problem that a specific antibody for resisting norovirus GII.4 genotype VP1 protein is lacked in the prior art, and provides an antibody specifically binding norovirus GII.4 genotype VP1 protein or VLP, and a preparation method and application thereof.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
an antibody which specifically binds to norovirus gii.4 genotype VP1 protein or VLP, comprising the CDR1, CDR2 and CDR3 regions of the heavy chain variable region shown in SEQ ID nos. 1-3 and/or the CDR1, CDR2 and CDR3 regions of the light chain variable region shown in SEQ ID nos. 4-6.
Another aspect of the invention provides an antibody that specifically binds to norovirus GII.4 genotype VP1 protein or VLP, comprising the heavy chain variable region amino acid sequence as set forth in SEQ ID No.10 and/or the light chain variable region amino acid sequence as set forth in SEQ ID No. 11.
Another aspect of the invention provides an antigen-binding portion which specifically binds to norovirus GII.4 genotype VP1 protein or VLP, comprising the CDR1, CDR2 and CDR3 regions of the heavy chain variable region shown in SEQ ID nos. 1-3 and/or the CDR1, CDR2 and CDR3 regions of the light chain variable region shown in SEQ ID nos. 4-6;
wherein said antigen binding portion is selected from the group consisting of Fab, Fab ', F (ab')2Fd, dAb, a complementarity determining region fragment, a single chain antibody, a humanized antibody, a chimeric antibody or a diabody.
The antigen-binding portion that specifically binds to norovirus gii.4 genotype VP1 protein or VLP can be obtained using methods well known to those skilled in the art, such as treatment with a chemical agent, or digestion with a protease, such as papain, pepsin, and the like.
In the present invention, sequences having 90% or more homology (preferably 95% or more) with the above-mentioned CDR amino acid sequences are also considered to be included in the scope of the present invention. Likewise, other variations of the above-described CDR amino acid sequences, such as deletion, insertion and/or substitution of one or more amino acids, addition of one or more amino acids at the C-terminus and/or N-terminus, and the like, are considered to be included within the scope of the present invention as long as they do not alter the biological function of the above-described CDR amino acid sequences.
The antibody of the present invention may be a polyclonal antibody or a monoclonal antibody. Preferably, however, in one embodiment of the present invention, the antibody of the present invention is a monoclonal antibody.
Preferably, in one embodiment of the present invention, the antibody is a monoclonal antibody produced by a cell having a accession number of CGMCC NO. 15696. The cell is a hybridoma obtained by fusing immunized host spleen cells and myeloma cells, is preserved in China general microbiological culture Collection center (CGMCC), has a preservation number of CGMCC NO.15696 and a preservation date of 2018, 04 months and 27 days.
The antibody provided by the invention is a type-specific antibody, can only be specifically combined with norovirus GII.4 genotype VP1 protein or VLP, and has no cross reaction to GI.1 genotype.
In the present invention, the antibody has a neutralizing activity, and is capable of blocking binding of VLPs to HBGA.
Preferably, in one embodiment of the invention, the antibody is a monovalent or bivalent antibody.
In the present invention, the monoclonal antibody can be prepared by a hybridoma preparation method as reported by Kohler et al, Nature 256:495 (1975). Mice or other suitable host animals are first immunized with the immunogen (with adjuvant added if necessary). In the invention, the immunogen is a virus-like particle (VLP) formed by the norovirus GII.4 genotype VP1 protein obtained after chromatography purification and generated by Hansenula polymorpha cell expression and/or the norovirus GII.4 genotype VP1 protein automatically assembled in vitro. The amino acid sequence of the antigen is shown in SEQ ID NO. 16.
The mode of injection of the immunogen or adjuvant is usually subcutaneous multi-site injection or intraperitoneal injection. Freund's adjuvant (Freund's complete adjuvant or Freund's incomplete adjuvant) or MPL-TDM, etc. can be used as the adjuvant. After an animal is immunized, lymphocytes that secrete antibodies that specifically bind the immunogen are produced in vivo. The lymphocytes of interest are harvested and fused with myeloma cells using a suitable fusing agent (e.g., PEG4000) to obtain hybridoma cells (Goding, Monoclonal Antibodies: Principles and Practice, pp.59-103, Academic Press, 1996).
The hybridoma cells prepared as described above are inoculated into a suitable medium containing one or more substances capable of inhibiting the growth of unfused, maternal myeloma cells. For example, for parental myeloma cells that lack hypoxanthine guanine phosphotransferase (HGPRT or HPRT), the addition of hypoxanthine, aminopterin, and thymidine (HAT medium) to the culture medium will inhibit the growth of HGPRT-deficient cells.
Preferred myeloma cells should have high fusion rate, stable antibody secretion ability, sensitivity to HAT medium, and the like. Among them, THE myeloma cells are preferably derived from murine myelomas such as MOP-21 and MC-11 mouse tumor-derived strains (THE salt Institute Cell Distribution Center, San Diego, Calif. USA), and SP-2/0 or X63-Ag8-653 Cell strain (American Type C. mu. culture Collection, Rockville, Md. USA). In addition, human Monoclonal antibodies can also be prepared using human myeloma and human murine allogeneic myeloma cell lines (Kozbor, J.Immunol., 133:3001 (1984); Brodeur et al, Monoclonal Antibody Production Techniques and Applications, pp.51-63, Marcel Dekker, Inc., New York, 1987).
The culture medium in which the hybridoma cells are grown is used to detect the production of monoclonal antibodies directed against specific antigens. The binding specificity of the monoclonal antibodies produced by the hybridoma cells can be determined using the following methods: immunoprecipitation or in vitro binding assays, such as Radioimmunoassay (RIA), enzyme-linked immunosorbent assay (ELISA). For example, the affinity of a mAb can be determined using the Scatchard assay described by Munson et al, anal. biochem.107:220 (1980).
After determining the specificity, affinity and reactivity of the Antibodies produced by the hybridomas, the cell lines of interest can be identified by Goding, Monoclonal Antibodies: subcloning was performed by limiting dilution as described by Principles and Practice, pp.59-103, Academic Press, 1996. Suitable media may be DMEM or RPMI-1640 or the like. In addition, hybridoma cells can also be grown in animals as ascites tumors.
The monoclonal antibody secreted by the subcloned cells can be separated from cell culture fluid, ascites fluid or serum by using a traditional immunoglobulin purification method, such as protein A agarose gel, hydroxyapatite chromatography, gel electrophoresis, dialysis or affinity chromatography, and the monoclonal antibody can be obtained.
Preferably, in one embodiment of the present invention, the obtained monoclonal antibody is numbered 302.
Another aspect of the present invention provides a polynucleotide encoding the above heavy chain variable region amino acid sequence or light chain variable region amino acid sequence.
Preferably, in one embodiment of the present invention, the polynucleotide sequence encoding the amino acid sequence of the heavy chain variable region is represented by SEQ ID NO.12, and the polynucleotide sequence encoding the amino acid sequence of the light chain variable region is represented by SEQ ID NO. 13.
Another aspect of the present invention provides a vector comprising the polynucleotide as described above.
Another aspect of the invention provides a kit comprising an antibody or antigen-binding portion thereof of the invention that specifically binds to norovirus gii.4 genotype VP1 protein or VLP.
Preferably, in one embodiment of the invention, the kit further comprises a second antibody that specifically binds to norovirus gii.4 genotype VP1 protein or VLP.
In the above kit, the second antibody may be any antibody known in the art against the gii.4 genotype VP1 protein or VLP, so that the sample is detected using a double sandwich method.
More preferably, the second antibody comprises the CDR1, CDR2 and CDR3 regions of the heavy chain variable region shown in SEQ ID Nos. 7-9.
Preferably, in one embodiment of the present invention, the second antibody comprises the heavy chain variable region amino acid sequence shown as SEQ ID No. 14.
Preferably, in one embodiment of the invention, the second antibody comprises an amino acid sequence encoded by the heavy chain variable region nucleotide sequence set forth in SEQ ID No. 15.
More preferably, the second antibody is a monoclonal antibody produced by a cell with the collection number of CGMCC NO.15695, which is collected in China general microbiological culture Collection center (CGMCC) with the collection date of 2018, 04 and 27 days.
Preferably, in one embodiment of the present invention, the second monoclonal antibody is obtained under the reference numeral 202.
Preferably, in one embodiment of the present invention, the second antibody is prepared using the same method as the antibody of the present invention which specifically binds to norovirus gii.4 genotype VP1 protein or VLP.
Another aspect of the invention is to provide the use of an antibody, antigen-binding portion, polynucleotide, vector or kit as described above for detecting the presence or level of norovirus gii.4 genotype VP1 protein or VLP in a sample.
The invention has the beneficial effects that:
the antibody or antigen binding part specifically binding to the norovirus GII.4 genotype VP1 protein or VLP provided by the invention has no cross reaction with the GI.1 genotype, has high specificity, has the characteristic of blocking the binding of the norovirus GII.4 genotype VP1 protein or VLP and HBGA, and has high affinity. Can be used for detecting the existence or the development of a kit for detecting the norovirus GII.4 genotype VP1 protein or VLP in a sample, treating patients and carrying out passive immunization on susceptible people, and has good application prospect.
Biological preservation information:
the preservation number is: CGMCC NO.15696
The preservation date is as follows: 04 month and 27 days 2018
The preservation unit: china general microbiological culture Collection center (CGMCC) for short, the address: microbial research institute of western road 1 institute No. 3 of China academy of sciences, Beijing, Chaoyang
The preservation number is: CGMCC NO.15695
The preservation date is as follows: 04 month and 27 days 2018
The preservation unit: china general microbiological culture Collection center (CGMCC) for short, the address: microbial research institute of western road 1 institute No. 3 of China academy of sciences, Beijing, Chaoyang
Detailed Description
The invention discloses an antibody specifically binding norovirus GII.4 genotype VP1 protein or VLP, and a preparation method and application thereof, and can be realized by appropriately improving process parameters by referring to the content. It is expressly intended that all such alterations and modifications which are obvious to those skilled in the art are deemed to be incorporated herein by reference, and that the techniques of the invention may be practiced and applied by those skilled in the art without departing from the spirit, scope and range of equivalents of the invention.
In the present invention, unless otherwise specified, scientific and technical terms used herein have the meanings that are commonly understood by those skilled in the art. Also, cell culture, molecular genetics, nucleic acid chemistry, immunology laboratory procedures, as used herein, are conventional procedures that are widely used in the relevant art. Meanwhile, in order to better understand the present invention, the definitions and explanations of related terms are provided below.
The term "antibody", as used herein, refers to an immunoglobulin molecule typically composed of two pairs of polypeptide chains, each pair having one "light" (L) chain and one "heavy" (H) chain. Antibody light chains can be classified as kappa and lambda light chains. Heavy chains can be classified as μ, δ, γ, α or ε, and the antibody isotypes are defined as IgM, IgD, IgG, IgA, and IgE, respectively. Within the light and heavy chains, the variable and constant regions are connected by a "J" region of about 12 or more amino acids, and the heavy chain also contains a "D" region of about 3 or more amino acids. Each heavy chain consists of a heavy chain variable region (VH) and a heavy chain constant region (CH). The heavy chain constant region consists of 3 domains (CH1, CH2, and CH 3). Each light chain consists of a light chain variable region (VL) and a light chain constant region (CL). The light chain constant region consists of one domain CL. The constant region of the antibody may mediate the binding of the immunoglobulin to host tissues or factors, including various cells of the immune system (e.g., effector cells) and the first component of the classical complement system (C1 q). The VH and VL regions can also be subdivided into regions of high denaturation, called Complementarity Determining Regions (CDRs), interspersed with regions that are more conserved, called Framework Regions (FRs). Each VH and VL are composed of, in the following order: FR1, CDR1, FR2, CDR2, FR3, CDR3, FR4 are composed of 3 CDRs and 4 FRs arranged from amino terminus to carboxy terminus. The variable regions (VH and VL) of each heavy/light chain pair form the antibody binding sites, respectively. The term "antibody" is not limited by any particular method of producing an antibody. For example, it includes, in particular, recombinant antibodies, monoclonal antibodies and polyclonal antibodies. The antibody may be of a different isotype, for example, an IgG (e.g., IgG1, IgG2, IgG3, or IgG4 subtype), IgA1, IgA2, IgD, IgE, or IgM antibody.
The term "antigen-binding portion" as used herein refers to a polypeptide comprising a fragment of a full-length antibody that retains the ability to specifically bind to the same antigen to which the full-length antibody binds, and/or bindsFull-length antibodies compete for specific binding to the antigen, which is also referred to as "antigen-binding fragments. See generally, Fundamental Immunology, Ch.7(Paul, W., ed., 2 nd edition, Raven Press, N.Y. (1989), which is incorporated herein by reference in its entirety for all purposes2Fd, Fv, etc.
Wherein, the term "Fab fragment" means an antibody fragment consisting of the VL, VH, CL and CH1 domains; the term "F (ab')2By fragment "is meant an antibody fragment comprising two Fab fragments connected by a disulfide bridge at the hinge region. The term "Fd fragment" means an antibody fragment consisting of the VH and CH1 domains; the term "Fv fragment" means an antibody fragment consisting of the VL and VH domains of a single arm of an antibody.
Herein, when the term "antibody" is referred to, it includes not only intact antibodies, but also antigen-binding fragments of antibodies, unless the context clearly indicates otherwise.
The term "monoclonal antibody" as used herein refers to an antibody or a fragment of an antibody from a population of highly homologous antibody molecules, i.e., a population of identical antibody molecules except for natural mutations that may occur spontaneously. Monoclonal antibodies have high specificity for a single epitope on the antigen. Polyclonal antibodies are relative to monoclonal antibodies, which typically comprise at least 2 or more different antibodies that typically recognize different epitopes on an antigen. Monoclonal antibodies are generally obtained using hybridoma technology first reported by Kohler et al (Nature,256:495,1975), but can also be obtained using recombinant DNA technology (see, e.g., U.S. P4, 816, 567).
The term "specific binding" as used herein refers to a non-random binding reaction between two molecules, such as between an antibody and the antigen against which it is directed.
The term "neutralizing antibody" as used herein refers to an antibody or antibody fragment that is capable of clearly or significantly reducing the virulence of a target virus or pseudovirus.
The term "epitope" as used herein refers to a linear epitope or a conformational epitope on an antigen at a site to which an immunoglobulin or antibody specifically binds.
"monoclonal antibody" and "monoclonal antibody" as used herein have the same meaning and are used interchangeably.
In the present invention, amino acids are generally represented by the single and three letter abbreviations known in the art, such as: alanine can be represented by A or Ala.
In the present invention, the term "adjuvant" refers to a non-specific immunopotentiator which, when mixed with an antigen, can enhance the immune response of the body to the antigen or change the type of immune response, and includes, but is not limited to, aluminum adjuvants such as aluminum hydroxide, Freund's complete adjuvant, Freund's incomplete adjuvant, etc.
In the invention: the term "norovirus VLPs" refers to virus-like particles assembled from norovirus VP1 proteins expressed in vitro, e.g., norovirus gii.4VP 1-VLPs refer to virus-like particles assembled from norovirus gii.4VP1 proteins expressed in vitro.
In order to make those skilled in the art better understand the technical solution of the present invention, the following detailed description of the present invention is provided with reference to specific embodiments.
The main instruments and reagents used in this embodiment:
1. main reagent, kit and consumable
Freund's complete adjuvant (CFA), Freund's incomplete adjuvant (IFA) and PEG4000 were purchased from Sigma.
DMEM medium (containing 2% HAT) and Fetal Bovine Serum (FBS) were purchased from HyClone, USA.
HRP-conjugated goat anti-mouse IgG Fc was purchased from Jackson Immun, usa.
HRP substrate A and B were purchased from Beijing DuPont Biotechnology Ltd.
Protein G affinity column materials were purchased from general electric (china) medical group.
Sepharose CL-4B gel filtration was from general electric (China) medical group.
10% dimethyl sulfoxide protective solution: contains 10% of dimethyl sulfoxide, 20% of inactivated fetal calf serum and 70% of RPMI-1640 liquid.
20% FCS-1640 medium: contains 100U/ml of penicillin and 100 mu g/ml of streptomycin.
HBGA is available from GlycoTech.
The other reagents are all domestic analytical pure products.
2. Main instrument
CO2Incubators were purchased from SANYO corporation.
Biosafety cabinets were purchased from Baker corporation.
Inverted fluorescence microscope was purchased from Olympus corporation.
Flow cytometry was purchased from BD.
The microplate reader was purchased from berle life medicine products (shanghai) ltd.
IMMAGE 800 is available from Beckmann Kulter, Inc., USA.
The UV spectrophotometer was purchased from Leiberttaceae, Inc.
3. Laboratory animals and cell lines
The experimental animal is an SPF-grade Balb/c female mouse, is 8-12 weeks old and has the weight of about 28g, and is purchased from Beijing Wintonlifa experimental animals technology Limited company and is bred under the barrier condition.
SP 2/0 cells were purchased from biotechnology limited, tokyo banko.
Example 1 preparation and selection of hybridoma cells
1. Preparation of immunogens
The immunogen used for preparing the monoclonal antibody of the norovirus GII.4VP1 protein is the norovirus GII.4VP1-VLP protein, the amino acid shown as SEQ ID NO.16 is expressed by hansenula polymorpha cells through in vitro recombination, the amino acid can be automatically assembled into VLP, and the VLP can be observed by a transmission electron microscope to be shown as a virus-like particle shown in figure 1, and the diameter of the particle is between 20 and 40nm, and the particle is spherical. Norovirus GII.4VP1-VLP protein was mixed with equal volume of Freund's complete adjuvant (CFA) or Freund's incomplete adjuvant (IFA), and fully emulsified by sonication to prepare the corresponding immunogen.
2. Animal immunization
On day 0, the immunogen mixed with CFA is injected into mice at multiple points through subcutaneous back injection, 3 mice are immunized for 0.2mg times/mouse, 4 times of immunization are carried out, the interval of each time is 1 week, the serum of the mice is collected after 3 times of immunization, the antibody titer is detected by the indirect ELISA method shown below, the antibody titer of the serum of the mice is more than 1 ten thousand times, and the antibody titer can be used for cell fusion.
3. Indirect ELISA method
GII.4VP1 protein was coated on 96-well plates at 100 ng/well. Adding 100 μ l of PBS solution containing 5% skimmed milk powder into Negative Control (NC) wells, and standing overnight at 4 ℃; discarding the liquid in the hole, washing the plate with PBS for 3 times, adding PBS solution containing 5% skimmed milk powder, sealing at 200 μ l/hole for 1 hr at room temperature; discarding the liquid in the wells, washing the plate for 1 time by PBST, adding primary antibody (tail blood is diluted according to the proportion of 1: 10000; hybridoma cell culture supernatant is diluted according to the proportion of 1:10 and the gradient of 2 times; mouse ascites is diluted according to the gradient of 3 times from the proportion of 1: 10000) and incubating for 1 hour at room temperature; discarding the liquid in the hole, washing the plate for 3 times by PBST, adding goat anti-mouse IgG Fc coupled with HRP (diluted in a ratio of 1: 10000), and incubating for 1 hour at room temperature; washing the PBST for 3 times, adding the substrate A and the substrate B, reacting at 50 mu l/hole in a dark place at room temperature for 15 min; the reaction was stopped by adding 1mol/L sulfuric acid, and the A450/630 value was measured by a microplate reader, using A450/630 (positive) >2 times A450/630(NC) as a standard.
4. Preparation and screening of hybridoma cells
The mouse with the highest antibody titer was taken for fusion. 3 days before the fusion, the cells were fused by boosting with the immunogen mixed with IFA at a concentration of 0.08 ml/cell and spleen cells were isolated from the spleen. Firstly, separating single splenocytes, fusing the splenocytes with mouse myeloma SP 2/0 cells by PEG4000(500g/L) according to the proportion of 4:1, and culturing the cells in a 96-well plate at the constant temperature of 37 ℃ for 14 days by using a DMEM medium containing 20% FBS and 2% HAT; collecting supernatant, screening positive clone cells, further performing expanded culture by using a DMEM medium containing 20% FBS, collecting supernatant, performing re-screening, performing expanded culture on the re-screened positive clone cells, collecting supernatant, performing cryopreservation and resuscitation to obtain positive clones, and collecting supernatant. The culture supernatant was detected by indirect ELISA and positive cell lines were selected. The results are shown in Table 1. 30 positive cell lines were selected from 400 cell lines, and 13 cell lines in total, in which antibodies against GII.4VP1 protein were stably secreted, were finally selected, with NC as a negative control.
TABLE 1 ELISA test results of cell strain supernatants stably secreting anti-GII.4 VP1 protein antibody
5. Specific antibody detection of hybridoma cell secretory supernatant
The coating antigens were GII.4VP1 protein and GI.1 VP1 protein, 100 ng/well, respectively, using an indirect ELISA method. The results of the detection of the antibody secreted from the cell supernatant by the 13 hybridoma cells showed that the antibody secreted from the cell supernatant by the 13 hybridoma cells reacted positively only with the gii.4VP1 protein (as shown in table 1), and was negative to the gi.1 VP1 protein, and thus the 13 hybridoma cells were determined to be type-specific antibodies.
6. Detection of neutralizing antibody Activity (HBGA-VLP blocking assay)
The neutralizing activity of the antibody and its antibody titer were tested by Synthetic HBGA-VLPs blocking assay.
The specific method comprises the following steps:
1) HBGA is added into an avidin coated microporous plate, 2.5 mu g/ml and 100 mu l of HBGA is added into each hole, the avidin coated microporous plate is incubated at 25 ℃ for 1 hour, then the solution in the plate is discarded, and the plate is washed for 3 times by phosphate buffer for later use.
2) Diluting the serum or antibody to be detected by a dilution plate in a 2-fold gradient manner, fully mixing the diluted serum or antibody with norovirus GII.4VP1-VLP solution with the same volume (1.6 mu g/ml), simultaneously setting a quality control serum control, a positive control (serum-free maximum combined VLPs holes) and a blank control (diluent holes), incubating for 1 hour at 37 ℃,
3) pipette 100 μ l of VLP and serum, antibody or diluent mixture slowly into the blocked plate, incubate at 4 ℃ for 2 hours, wash the plate with phosphate buffer 3 times.
4) HRP-labeled gii.4VP1 rabbit polyclonal antibody was diluted to working concentration (1: 16000) The cells were added to a microplate in an amount of 100. mu.l/well, incubated at 4 ℃ for 1 hour, and washed 3 times with phosphate buffer.
5) Color development: and sequentially adding 50 mul of color developing agent A and 50 mul of color developing agent B into each hole, uniformly mixing, adding 50 mul of stop solution into each hole to stop reaction at room temperature for 5 minutes, and performing double-wavelength reading (A450nm/630nm) in an enzyme-linked immunosorbent assay.
6) And (4) calculating a result: with BT50The reaction neutralizes antibody titers. BT (BT)50I.e. the highest dilution of serum capable of blocking 50% of norovirus gii.4VP 1-VLPs from binding to the HBGA receptor.
TABLE 2 detection of neutralizing antibody Activity of hybridoma cell secretion supernatants
7. Detection of neutralizing antibody Activity (PGM-VLP blocking assay)
A96-well microplate was coated with 5. mu.g/ml of porcine gastric mucin III (PGM) (100. mu.l/well) of Yuanmu biosciences, Shanghai, Ltd. (100. mu.l/well) at room temperature (25 ℃ C.), and blocked with 5% skim milk-containing PBST at 4 ℃ overnight for use. A GII.4VLP-specific monoclonal antibody 10. mu.g/ml was started, diluted by 16 gradients in 2-fold proportion, incubated with an equal volume of 0.5. mu.g/ml of GII.4VLP at 37 ℃ for 1 hour, applied to a PGM-coated 96-well microplate, incubated at room temperature (25 ℃) for 1 hour, then HRP-labeled rabbit anti-GII.4 virus-like particle polyclonal antibody (1:1000 dilution) was added, incubated at room temperature (25 ℃) for 1 hour, and finally the absorbance OD450 was read.
8. Ascites preparation, antibody purification and antibody titer detection
Ascites was prepared from 12 selected hybridoma cells having neutralizing activity, 2 mice were inoculated with each positive clone, ascites was collected 10 to 14 days later, and ELISA was performed for antibodies in the ascites, the results of which are shown in Table 3. Then, ascites is purified by utilizing a Protein A affinity column to obtain a purified antibody, an A280 value is measured by an ultraviolet spectrophotometer, and the concentration of the antibody is calculated.
TABLE 3 mouse ascites antibody ELISA test results
9. Subculturing and preserving hybridoma cells
After the hybridoma cells were cultured and passaged in a DMEM medium containing 10% fetal calf serum until 10 passages, 2H7-C5(202) and 2E6-B3(302) stably secreted monoclonal antibodies against GII.4VP1 protein, and the cells grew well.
After obtaining hybridoma cells producing the desired monoclonal antibody, a portion of the hybridoma cells are preserved, otherwise, during serial passages, mutations or chromosomal shifts may occur such that the intrinsic properties are lost or antibody-producing properties are lost; in addition, in the long-term culture process, pollution and destruction cannot occur inevitably, so that the cell strain is necessary to be preserved. The preservation method comprises the following steps: the old culture medium in the cell culture flask was removed, and 10% FCS-1640 solution was added to suspend the cells. Centrifuging at 1000rpm/min for 10min, and removing supernatant. The cell sediment is made into suspension by using 10% dimethyl sulfoxide protective solution, so that the suspension is 1.0 multiplied by 107Cells/ml. Sampling, staining with trypan blue, and counting the number of living cells to be more than 95%. Finally, the cells were dispensed into ampoules, 0.5-1.0 ml per vial, using sterile syringes, and the ampoules were sealed by fusion. Standing at 4 deg.C for 2 hr, transferring into refrigerator at-70 deg.C for 15 hr, and freezing in liquid nitrogen.
Example 22 identification of E6-B3(302) antibodies
1. Obtaining antibodies
Adult BALB/c mice were selected and intraperitoneally inoculated with 0.5ml of pristane per mouse. The 16 th generation of 2E6-B3(302) hybridoma cells were intraperitoneally inoculated 7-10 days later, at 1X 10/mouse6-2×106And (4) respectively. After 5 days, when the abdomen is obviously enlarged and the hand touches the abdomen, the skin is tense, and the ascites is collected by using a 9-gauge needle.
2. Purification of antibodies
Ascites was centrifuged at 13000rpm for 30 minutes, the cell fraction and other precipitates were removed, and the supernatant was collected. The monoclonal antibody 2E6-B3(302) of the GII.4VP1 Protein was finally obtained by purification using Protein A affinity chromatography at a concentration of 5mg/ml or more.
3. Antibody purity detection
The purified antibody was subjected to 12% SDS-PAGE, and the purity was found to be 95% or more.
4. Determination of antibody light chain and heavy chain variable region gene sequence
Extracting mRNA of 2E6-B3(302) hybridoma cells, performing reverse transcription to cDNA, performing high fidelity PCR amplification by using variable region universal primers, inserting PCR product fragments into a T vector for DNA sequence determination, and performing DNA sequence determination on the variable region gene sequence of 2E6-B3 (302): the heavy chain is shown as SEQ ID NO.12, and the light chain is shown as SEQ ID NO. 13. The obtained nucleotide sequence is translated into an amino acid sequence. 2E6-B3(302) variable region amino acid sequence: the heavy chain is shown as SEQ ID NO.10, and the light chain is shown as SEQ ID NO. 11.
5. Detection of antibody type specificity
As shown by the specific antibody detection results in the supernatant secreted by the hybridoma cells 5 in example 1,
the 2E6-B3(302) antibody only reacted positively to the GII.4VP1 protein, and the detection result was negative to the GI.1 VP1 protein, which proved that the 2E6-B3(302) antibody was a type-specific monoclonal antibody.
6. Identification of neutralizing Activity of antibodies (HBGA-VLP blocking assay)
As shown by the result of the detection of the neutralizing activity of the antibody 6 in example 1, the 2E6-B3(302) antibody was a monoclonal antibody having a neutralizing activity. The purified 2E6-B3(302) antibody was diluted to 25. mu.g/ml, and then serially diluted in 2-fold gradient, and the antibody neutralization activity assay was performed according to 6. method for detecting the neutralizing antibody activity in example 1, and 2E6-B3(302) antibody was used for detecting BT bound to GII.4 and HBGA50The corresponding antibody concentration was 0.1953125. mu.g/ml.
7. Detection of neutralizing antibody Activity (PGM-VLP blocking assay)
As shown by the results of the detection of the neutralizing activity of the antibody of 7 in example 1, the 2E6-B3(302) antibody was a monoclonal antibody having a neutralizing activity. The purified 2E6-B3(302) antibody was diluted to 10. mu.g/ml, and then serially diluted in 2-fold gradient, and the antibody neutralization activity assay was carried out according to example 1, 7. neutralization antibody activity assay method, wherein the antibody concentration of 2E6-B3(302) antibody against GII.4 and PGM-bound BT50 was 0.0098. mu.g/ml.
Example 32 identification of H7-C5(202) antibodies
1. Obtaining antibodies
The same procedure as in example 2-1 was conducted, except that hybridoma cells 2H7-C5(202) were inoculated.
2. Purification of antibodies
The same procedures as in example 2-1 were carried out to finally obtain monoclonal antibody 2H7-C5(202) of GII.4VP1 protein at a concentration of 5mg/ml or more.
3. Detection of antibody purity
The same procedure as in example 2-1 was carried out, and as a result, the purity was found to be 95% or more.
4. Determination of antibody light chain and heavy chain variable region gene sequence
Extracting mRNA of 2H7-C5(202) hybridoma cells, performing reverse transcription to cDNA, performing high fidelity PCR amplification by using variable region universal primers, inserting PCR product fragments into a T vector for DNA sequence determination, and determining the variable region gene sequence of 2H7-C5 (202): the heavy chain is shown as SEQ ID NO. 15. The obtained nucleotide sequence is translated into an amino acid sequence. 2H7-C5 (202): the heavy chain is shown as SEQ ID NO. 14.
5. Detection of antibody type specificity
As shown in example 1, 5. the detection result of specific antibody in the supernatant secreted from hybridoma cell showed that 2H7-C5(202) antibody reacted positively only to GII.4VP1 protein and was negative to GI.1 VP1 protein, demonstrating that 2H7-C5(202) antibody is a type-specific monoclonal antibody.
6. Identification of neutralizing Activity of antibodies (HBGA-VLP blocking assay)
As shown by the results of the detection of the neutralizing activity of the antibody of 7 in example 1, the 2H7-C5(202) antibody was a monoclonal antibody having a neutralizing activity. The purified 2H7-C5(202) antibody was diluted to 25. mu.g/ml, and then serially diluted in 2-fold gradient, and the antibody neutralization activity assay was performed according to 6. method for detecting the neutralizing antibody activity in example 1, and the 2H7-C5(202) antibody was used to detect the BT bound to GII.4 and HBGA50Corresponding toThe antibody concentration was 3.125. mu.g/ml.
7. Detection of neutralizing antibody Activity (PGM-VLP blocking assay)
As shown by the result of the detection of the neutralizing activity of the antibody of 7 in example 1, the antibody 2H7-C5(202) is a monoclonal antibody having a neutralizing activity. The purified 2H7-C5(202) antibody was diluted to 10. mu.g/ml, and then serially diluted in 2-fold gradient, and the antibody neutralization activity assay was carried out according to example 1, 7. neutralization antibody activity assay method, wherein the antibody concentration of 2H7-C5(202) antibody against GII.4 and PGM-bound BT50 was 0.3125. mu.g/ml.
Example 4 GII.4VP1 antigen detection kit
The monoclonal antibodies 2H7-C5(202) and 2E6-B3(302) obtained in example 1 were used to develop a GII.4VP1 double antibody sandwich ELISA kit for detecting the antigen level of GII.4VP 1.
1. Establishment of double-antibody sandwich ELISA method
A. The principle of the kit is as follows:
both 2H7-C5(202) and 2E6-B3(302) were monoclonal antibodies specific for the GII.4VP1 type and having neutralizing activity. 2H7-C5(202) is used as a coating antibody, 2E6-B3(302) is used as an enzyme-labeled antibody, a double-antibody sandwich ELISA detection kit is established, when a sample solution to be detected or a standard solution is added into an enzyme-labeled plate which is pre-coated with the 2H7-C5(202) antibody, 2E6-B3(302) enzyme-labeled secondary antibody is added, color development is carried out by using a color development solution, the absorption value of the sample is positively correlated with the content of GII.4VP1 protein in the sample in a linear range, and the content of the GII.4VP1 protein in the sample can be obtained by comparing with a standard curve. Meanwhile, the concentration range of the GII.4VP1 protein in the sample can be roughly judged by comparing the color of the enzyme label plate with the color of the GII.4VP1 protein standard solution with a series of concentrations according to the color depth of the enzyme label plate.
B. The kit comprises the following components:
(1) elisa plate coated with coating antibody: the coating antibody is 2H7-C5(202) type specific monoclonal antibody, and is secreted and produced by hybridoma cell strain clone 2H7-C5(202) with the preservation number of CGMCC NO. 15695. The coated antibody is diluted to 3 mu g/ml by using a coating buffer solution, coated on a 96-well enzyme label plate, added with 100 mu l per well, and incubated for 8 hours at the temperature of 4 ℃. The coating solution was discarded, washed 3 times with washing solution and patted dry. Then, 100. mu.l of blocking solution was added to the microplate and incubated at 37 ℃ for 2 hours. Pouring out the liquid in the hole, drying, and storing in an aluminum film vacuum seal mode. Wherein the used coating buffer solution is a carbonate buffer solution with the pH value of 9.5 and 0.1 mol/L; the blocking solution used was a barbiturate sodium-hydrochloric acid buffer solution containing bovine serum albumin at a final concentration of 8% (mass percentage) in the blocking solution, having a pH of 8.6 and 0.1 mol/L.
(2) Enzyme-labeled antibody: the labeling enzyme is horseradish peroxidase, the labeling method is a sodium periodate method, the enzyme-labeled antibody is a 2E6-B3(302) type specific neutralizing monoclonal antibody, the enzyme-labeled antibody is secreted and generated by a hybridoma cell strain clone 2E6-B3(302) strain with the collection number of CGMCC NO.15696, and the working concentration of the enzyme-labeled antibody is 0.1 mu g/ml.
(3) Standard solution: GII.4VP1 protein standard solution, 7 bottles, at concentrations of 1. mu.g/ml, 0.5. mu.g/ml, 0.25. mu.g/ml, 0.125. mu.g/ml, 0.0625. mu.g/ml, 0.03125. mu.g/ml and 0.015625. mu.g/ml, respectively. The prepared standard solution is DMSO with a final concentration of 5-10% (mass percentage content) in the solution for preparing the standard, and phosphate buffer solution with a pH of 6.5-6.7 and a concentration of 0.1-0.2 mol/L.
(4) Substrate color developing solution: the color developing solution A is hydrogen peroxide, and the color developing solution B is o-phenylenediamine.
(5) The stop solution is 1-2mol/L sulfuric acid solution.
(6) Concentrating the washing solution: a phosphate buffer solution with a pH value of 8.5, a final concentration of 0.05% (mass percent) sodium azide in the concentrated washing solution, a final concentration of 2.0% (mass percent) tween-20 in the concentrated washing solution and 0.3 mol/L; 40 ml/bottle, 1 bottle.
(7) Concentrating the compound solution: contains DMSO with a final concentration of 5-10% (mass percentage content) in a double solution, and phosphate buffer solution with pH of 6.5-6.7 and 0.1-0.2 mol/L; 200 ml/bottle, 1 bottle.
(8) Kit instructions.
2. Kit specificity verification
The GII.4VP1 and GI.1 VP1 proteins are prepared into a test sample of 50 mu g/ml, and are respectively diluted into a diluent of 2 mu g/ml, 1 mu g/ml, 0.5 mu g/ml, 0.25 mu g/ml, 0.125 mu g/ml, 0.0625 mu g/ml and 0.03125 mu g/ml, and the two proteins of GII.4VP1 and GII.1 VP1 are subjected to ELISA detection by using the GII.4VP1 antigen detection kit, and the results are shown in Table 4, and it can be seen that the GII.4VP1 antigen detection kit detects the GII.4VP1 positively and the GI.1 VP1 proteins negatively, and the kit specificity is good.
TABLE 4 kit specificity verification test results
Note: negative control (sample dilution) OD450 < 0.05
3. Kit sensitivity verification
The lowest antigen concentration detected by the kit is the key for determining the sensitivity of the kit. The GII.4VP1 protein was formulated as a 50. mu.g/ml sample for testing, diluted to 1. mu.g/ml, 0.5. mu.g/ml, 0.25. mu.g/ml, 0.125. mu.g/ml, 0.0625. mu.g/ml, 0.03125. mu.g/ml and 0.015625. mu.g/ml, respectively. And (3) repeatedly measuring the diluted sample by using the kit for 6 times, taking the average value of the lower detection limit of the 6 standard curves, and finally determining the sensitivity of the kit to be 15.63 ng/ml.
4. Kit precision verification
A. Precision verification-in-plate differences
The gii.4VP1 protein was diluted to 1 μ g/ml, 0.5 μ g/ml, 0.25 μ g/ml, 0.125 μ g/ml and 0.0625 μ g/ml for a total of 5 different antigen concentrations, with 5 replicates (n-6) per antigen concentration, with the sample dilutions serving as negative controls. The OD variation Coefficient (CV) between wells of the same concentration in the microplate was calculated, and the results are shown in table 5, in which the CV (%) values in the plate were less than 15%, indicating that the precision in the kit was good.
TABLE 5 in-board Difference verification results for reagent kit
B. Precision verification-inter-plate difference
The gii.4VP1 protein was diluted to 1 μ g/ml, 0.5 μ g/ml, 0.25 μ g/ml, 0.125 μ g/ml and 0.0625 μ g/ml for a total of 5 different antigen concentrations, with 5 replicates (n-6) per antigen concentration, with the sample dilutions serving as negative controls. The OD value variation Coefficient (CV) of each well of the same concentration between different elisa plates was calculated, and the results are shown in table 6, wherein the CV (%) between the plates was less than 15%, indicating that the precision between the elisa plates was good.
TABLE 6 verification results of inter-plate differences of kits
5. Kit accuracy verification
Diluting GII.4VP1 protein to 50ng/ml, 60ng/ml and 70ng/ml to serve as a standard solution, adding the standard solution into a test solution (240 mu g/ml), making a standard curve according to the content of VP1 protein and the absorbance value of the standard curve, calculating the concentration of GII.4VP1 protein in the test solution before and after adding the standard, calculating the sample recovery rate, and analyzing the accuracy of the kit. The results are shown in Table 7, and show that the recovery rate of the spiked standard (95% CI) is between 71.21 and 125.73%, and the recovery rate of the kit is good.
Table 7 kit accuracy verification results
6. Kit repeatability verification
Diluting GII.4VP1 protein to 7 concentrations of 1. mu.g/ml, 0.5. mu.g/ml, 0.25. mu.g/ml, 0.125. mu.g/ml, 0.0625. mu.g/ml, 0.03125. mu.g/ml and 0.015625. mu.g/ml, using the sample diluent as negative control, making standard curve corresponding to the absorbance value of GII.4VP1 protein in the sample, detecting 6 times for each type, and obtaining line of the standard curveCoefficient of correlation R2The results are shown in table 8, and the correlation coefficient R2 is not lower than 0.99, which indicates that the detection method has good linear correlation and repeatability.
TABLE 8 kit repeatability verification results
7. Shelf life test of kit
The storage condition of the kit is 2-8 ℃, and the maximum absorbance value (zero standard) of the kit and the actual measured value of the GII.4VP1 protein are within the normal range after 6 months of measurement. Considering that abnormal storage conditions occur in the transportation and use processes, the kit is placed for 6 days under the condition of being stored at 37 ℃ for accelerated aging experiments, and the results show that all indexes of the kit completely meet the requirements. And in consideration of the occurrence of the freezing condition of the kit, the kit is frozen for 5 days in a refrigerator at the temperature of-20 ℃, and the determination result also shows that all indexes of the kit are completely normal. From the above results, it was found that the kit could be stored at 2-8 ℃ for at least 6 months.
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> national institute of Biotechnology, Biotechnology limited; limited liability company of Beijing institute of biological products
<120> antibody specifically binding to norovirus GII.4 genotype VP1 protein and/or VLP, and preparation method and application thereof
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