CN109824775B - Foot-and-mouth disease A type Wuhan strain monoclonal antibody, composition and application thereof - Google Patents

Abstract

The invention discloses a monoclonal antibody for specifically detecting a foot-and-mouth disease type A Wuhan strain and application thereof. The monoclonal antibody is 1) a monoclonal antibody containing a heavy chain variable region 5G11-VH and a light chain variable region 5G 11-VL; the amino acid sequence of the 5G11-VH is shown as the 1 st to 128 th sites of SEQ ID No.1 in the sequence table; the amino acid sequence of 5G11-VL is shown as 1 st to 115 th sites of SEQ ID No.2 in a sequence table; or 2) comprises the heavy chain variable region 1C10-VH and the light chain variable region 1C 10-VL. Can be used as a capture antibody or a detection antibody to be prepared into an enzyme linked immunosorbent assay kit, and does not have cross reaction with other strains of the current foot-and-mouth disease when being detected. The enzyme linked immunosorbent assay kit prepared from the monoclonal antibody and the composition thereof has high sensitivity, good specificity and convenient operation, and can stably detect the antigen content and specificity of the foot-and-mouth disease A type Wuhan strain and distinguish the foot-and-mouth disease A type Wuhan strain from other strains.

Description

Foot-and-mouth disease A type Wuhan strain monoclonal antibody, composition and application thereof

Technical Field

The invention belongs to the technical field of biological detection, and particularly relates to a monoclonal antibody for specifically and quantitatively detecting a foot-and-mouth disease type A Wuhan strain and application thereof, which are suitable for specific, rapid and accurate detection of a foot-and-mouth disease type A Wuhan strain antigen.

Background

Foot-and-mouth disease (FMD) is a virulent infectious disease of artiodactyl animals caused by FMDV (foot-and-mouth disease virus) infection. Foot and mouth disease has a low mortality rate, but the infection rate is high. The main symptoms of the onset are: blisters occur on the oral mucosa, tongue, lip, nasoscope, hoof fork, nipple, etc., which are broken to form spots, and the edge of the hoof shell of the sick livestock is cracked or peeled off in the lying place and in the severe place. Different animals have slightly different symptoms, and pregnant cows can be aborted and then have reduced fecundity; the pig has broken hoof as the main symptom; goat and sheep are generally milder symptomatic than cattle. Foot and mouth disease infectivity is high, spread rapidly, infect pig, ox, sheep etc. livestock often lead to the death of young animal, adult animal's productivity drops sharply, seriously jeopardize the development of animal husbandry and the production supply of animal products. The animal disease is widely distributed in the world, can infect more than 70 kinds of domestic and wild animals, has extremely high incidence (about 100 percent) and seriously affects the animal husbandry production and International trade, so the animal disease is highly valued by various countries and is listed as a legal report animal disease by the world animal health organization (Office International Des epidemiology, OIE).

Foot and Mouth Disease Virus (FMDV) is a member of the picornaviridae (picornavi-ridae), the foot and mouth disease virus (aphthvirus) family, and consists of a single-stranded, plus-stranded RNA of about 8500 nucleotides in length and a capsid protein. The viral capsid is composed of 60 copies each of 4 structural proteins, VP1, VP2, VP3 and VP4, of which VP1 and VP3 are the major immunizing antigens. Foot-and-mouth disease virus (FMDV) has the characteristics of polymorphism, changeability and the like, has 7 serotypes, namely A, O, C, SATI, SATII, SATIII and AsiaI types, and has no cross protection reaction among the types. Currently, the main popular types in China are O type, A type (A/WH/09 strain) and Asia type 1 (JSL/06 strain).

At present, sucrose density gradient centrifugation is mainly used as a method for measuring the foot-and-mouth disease 146S antigen, but the method is complex to operate, needs 3 days to complete, is long in time consumption, cannot distinguish serotypes, and cannot distinguish different strains of the same serotype, so that a more specific, sensitive, accurate and reliable detection method needs to be developed to distinguish different serotypes and strains of the foot-and-mouth disease.

At present, Enzyme-Linked immunosorbent assays (ELISA) are the mainstream immunoassay technology in the market, are widely applied to clinical detection, are rapid and convenient, have high sensitivity, do not need special instruments and equipment, and can be used for detecting the foot-and-mouth disease 146S antigen. In the current market, most of ELISA kits for detecting foot-and-mouth disease antigens adopt polyclonal antibodies, for example, "A type foot-and-mouth disease 146S antigen quantitative ELISA detection method and kit and application thereof" developed by Lanzhou veterinary research institute of Chinese academy of agricultural sciences, the kit patent (application No. CN201310017209.4) shows that A type foot-and-mouth disease rabbit antiserum is adopted as a capture antibody, horse radish peroxidase-labeled guinea pig antiserum is adopted as a detection antibody, the A type can be distinguished from the O type and Asia 1 type, but different strains of the A type cannot be distinguished, so that the foot-and-mouth disease 146S antigen of each strain in a multivalent vaccine cannot be singly quantitatively detected, the main reason is that the polyclonal antibodies aim at multiple antigen epitopes, the homology among different serotypes, particularly different strains of the same serotype is very high, can exceed 85%, and only a few dozens or even a few amino acid sequences can be different, the same epitope may exist, so that the double-antibody sandwich ELISA antigen detection kit established according to the polyclonal antibody cannot distinguish and quantitatively detect the foot-and-mouth disease viruses of different strains of the same serotype. The monoclonal antibody is an antibody prepared by screening aiming at a single epitope on an antigen, can identify foot-and-mouth disease viruses of different strains in a homologous manner, and is a basis for establishing a foot-and-mouth disease 146S antigen quantitative ELISA kit for distinguishing different strains of the same serotype.

Disclosure of Invention

The invention aims to provide a monoclonal antibody capable of specifically detecting an antigen of a foot-and-mouth disease type A Wuhan strain.

The invention also claims a monoclonal antibody which can be specifically combined with the Wuhan strain 146S antigen of the foot-and-mouth disease A type and is any one of the following monoclonal antibodies:

1) containing heavy chain variable region 5G11-V_HAnd light chain variable region 5G11-V_L(ii) a The 5G11-V_HAnd 5G11-V_LBoth consist of a determinant complementary region and a framework region; the 5G11-V_HAnd said 5G11-V_LEach of the determinant complementary regions of (a) consists of a CDR1, a CDR2 and a CDR 3; the 5G11-V_HThe amino acid sequence of the CDR1 is shown as amino acids 25 to 34 of SEQ ID No. 1; the 5G11-V_HThe amino acid sequence of the CDR2 is shown as amino acids 51-58 of SEQ ID No. 1; the 5G11-V_HThe amino acid sequence of the CDR3 is shown as amino acids 98-114 of SEQ ID No. 1; the 5G11-V_LThe amino acid sequence of CDR1 is as shown in SEQ ID No.2Amino acids at positions 24-35; the 5G11-V_LThe amino acid sequence of the CDR2 is shown as amino acids 49-58 of SEQ ID No. 2; the 5G11-V_LThe amino acid sequence of the CDR3 is shown as amino acids 95-98 of SEQ ID No. 2;

2) containing the heavy chain variable region 1C10-V_HAnd light chain variable region 1C10-V_L1C10-V as described_HAnd 1C10-V_LBoth consist of a determinant complementary region and a framework region; the 1C10-V_HAnd said 1C10-V_LEach of the determinant complementary regions of (a) consists of a CDR1, a CDR2 and a CDR 3; the 1C10-V_HThe amino acid sequence of the CDR1 is shown as amino acids 26-36 of SEQ ID No. 3; the 1C10-V_HThe amino acid sequence of the CDR2 is shown as amino acids 54-61 of SEQ ID No. 3; the 1C10-V_HThe amino acid sequence of the CDR3 is shown as amino acids 98-111 of SEQ ID No. 3; the 1C10-V_LThe amino acid sequence of the CDR1 is shown as amino acids 24-36 of SEQ ID No. 4; the 1C10-V_LThe amino acid sequence of the CDR2 is shown as amino acids 50-59 of SEQ ID No. 4; the 1C10-V_LThe amino acid sequence of CDR3 is shown as amino acids 94-99 of SEQ ID No. 4.

3) Containing heavy chain variable region 5G11-V_HAnd light chain variable region 5G11-V_L(ii) a The 5G11-V_HThe amino acid sequence of (A) is shown as 1 st to 128 th sites of SEQ ID No.1 in a sequence table; its 5G11-V_LThe amino acid sequence of (A) is shown as 1 st to 115 th sites of SEQ ID No.2 in a sequence table;

4) containing the heavy chain variable region 1C10-V_HAnd light chain variable region 1C10-V_L1C10-V as described_HThe amino acid sequence of (A) is shown as 1 st to 127 th sites of SEQ ID No.3 in a sequence table; 1C10-V thereof_LThe amino acid sequence of (A) is shown as 1 st to 116 th sites of SEQ ID No.4 in the sequence table.

The heavy chain variable region and the light chain variable region sequences can be connected with animal-derived constant regions (such as heavy chain and light chain constant regions of a mouse antibody) to prepare the monoclonal antibody which can be specifically combined with the 146S antigen of the foot-and-mouth disease A type Wuhan strain (A/WH/09 strain).

The invention also provides a monoclonal antibody composition, which comprises the monoclonal antibodies 1) and 2) described in the specification; 1) comprises a heavy chain variable region 5G11-VH and a light chain variable region 5G 11-VL; the 5G11-VH and 5G11-VL each consist of a determinant complementary region and a framework region; the determinant complementary regions of the 5G11-VH and the 5G11-VL each consist of a CDR1, a CDR2 and a CDR 3; the amino acid sequence of the CDR1 of the 5G11-VH is shown as amino acids 25-34 of SEQ ID No. 1; the amino acid sequence of the CDR2 of the 5G11-VH is shown as amino acids 51-58 of SEQ ID No. 1; the amino acid sequence of the CDR3 of 5G11-VH is shown as amino acids 98-114 of SEQ ID No. 1; the amino acid sequence of the CDR1 of 5G11-VL is shown as amino acids 24-35 of SEQ ID No. 2; the amino acid sequence of the CDR2 of 5G11-VL is shown as amino acids 49-58 of SEQ ID No. 2; the amino acid sequence of the CDR3 of 5G11-VL is shown as amino acids 95-98 of SEQ ID No. 2;

2) comprises a heavy chain variable region 1C10-VH and a light chain variable region 1C10-VL, wherein each of the 1C10-VH and 1C10-VL comprises a determinant complementary region and a framework region; the determinant complementarity regions of the 1C10-VH and the 1C10-VL each consist of CDR1, CDR2 and CDR 3; the amino acid sequence of the CDR1 of 1C10-VH is shown as amino acids 26-36 of SEQ ID No. 3; the amino acid sequence of the CDR2 of 1C10-VH is shown as amino acids 54-61 of SEQ ID No. 3; the amino acid sequence of the CDR3 of 1C10-VH is shown as amino acids 98-111 of SEQ ID No. 3; the amino acid sequence of the CDR1 of 1C10-VL is shown as amino acids 24-36 of SEQ ID No. 4; the amino acid sequence of the CDR2 of 1C10-VL is shown as amino acids 50-59 of SEQ ID No. 4; the amino acid sequence of the CDR3 of 1C10-VL is shown as amino acids 94-99 of SEQ ID No. 4.

Preferably, the monoclonal antibody composition consists of the monoclonal antibodies described in the following 1) and 2):

1) comprises a heavy chain variable region 5G11-VH and a light chain variable region 5G 11-VL; the amino acid sequence of the 5G11-VH is shown as the 1 st to 128 th sites of SEQ ID No.1 in the sequence table; the amino acid sequence of 5G11-VL is shown as 1 st to 115 th sites of SEQ ID No.2 in a sequence table;

2) the light chain variable region comprises a heavy chain variable region 1C10-VH and a light chain variable region 1C10-VL, wherein the amino acid sequence of the 1C10-VH is shown as the 1 st to 127 th sites of SEQ ID No.3 in a sequence table; the amino acid sequence of 1C10-VL is shown as 1 st to 116 th of SEQ ID No.4 in the sequence table.

The application of the monoclonal antibody and the monoclonal antibody composition which can be specifically combined with the Wuhan strain 146S antigen of the foot-and-mouth disease A type in preparing the kit for detecting the foot-and-mouth disease is also within the protection scope of the invention. In particular to the application in the preparation of a kit for detecting the foot-and-mouth disease A type Wuhan strain (A/WH/09 strain) antigen.

The method for obtaining the monoclonal antibody capable of being specifically combined with the A-type Wuhan strain 146S antigen of the foot-and-mouth disease is as follows: monoclonal antibodies specific to the type A Wuhan strain of foot-and-mouth disease (A/WH/09 strain) of the present invention were prepared according to conventional methods known in the art. Specifically, the specific monoclonal antibody of the A-type Wuhan strain of foot-and-mouth disease (A/WH/09 strain) of the present invention may comprise the following steps:

1) obtaining 146S antigen with purity not lower than 80% by sucrose density gradient method (45%, 35%, 25%, 15%), adjusting the antigen concentration to 10 μ g/ml, and using it as immunogen;

2) immunizing animals with foot-and-mouth disease type A Wuhan strain (A/WH/09 strain) 146S antigen as immunogen for 4 times, with interval of 14 days, multipoint subcutaneous immunization mode for the first 3 times, intraperitoneal injection immunization mode for the 4 th time, and 10 μ g/animal each time;

3) separating splenocytes from immune animals, fusing the splenocytes with myeloma cells, screening hybridoma cells by using HAT selective culture medium, and screening specific positive clones from the supernatant of the hybridoma cells by using an indirect ELISA method; when the serum antibody level of the immunized animal is detected by indirect ELISA with the titer exceeding 1:50000, spleen cells of the animal can be separated and prepared into a single cell suspension, and fused with myeloma cells (preferably mouse myeloma cells SP2/0) under the induction of a proper fusing agent (such as polyethylene glycol) to form hybridoma, and then cultured in HAT medium to screen the fused hybridoma cells, and further a desired specific monoclonal antibody cell strain can be identified by using indirect ELISA and the like, and a monoclonal cell strain secreting 5G11 and a monoclonal cell strain secreting 1C10 are preferably two monoclonal cell strains paired for detecting the antigen of the Han strain of foot-and-mouth disease type A through pairing experiments.

4) Extracting total RNA of the specific positive clone hybridoma cell strain: taking 250 ul of hybridoma cell suspension, adding 750 ul of Trizol, turning upside down and mixing, adding 200 ul of chloroform, mixing, and centrifuging at 12000rpm at 4 ℃ for 15 min. The supernatant was pipetted into a new 1.5ml EP tube, 600. mu.l of isopropanol was added, mixed well and centrifuged for 10 min. The isopropanol was discarded, washed with 75% DEPC ethanol and centrifuged. The ethanol was discarded, oven dried and the RNA was dissolved in 20. mu.l of RNase-free water.

5) Reverse transcription, PCR amplification and gene sequencing: reverse transcription was performed using the Invitrogen reverse transcription kit as per the instructions to obtain cDNA for hybridoma cells. For the heavy chain (V)_H-1：5’-GTGAATTCATGCAGGTGCAGCTGTTGGAGTCTGG-3’；V_H-2: 5'-ATGTCGACTGAGGAGACGGTGACCAGGGTGCC-3') and light chain (V)_L-1：5’-GTGAATTCATGGACATTGTGATGACCCAGTCTCC-3’；V_L-2: 5'-CAGTCGACTTACGTTTGATCTCCAGCTTGGTCCC-3') designing universal primer for variable region, amplifying target segment with amplification primer, recovering segment after amplification, and connecting with carrier for sequence determination to obtain sequence information of heavy chain and light chain variable region of monoclonal antibody.

6) Synthesis of gene sequence of specific monoclonal antibody, construction of shuttle vector, screening and extraction of recombinant Bacmid, and rescue of recombinant baculovirus: synthesis of gene sequence: according to the sequences of the heavy and light chain variable regions that have been determined for mAbs 1E10 and 7G2, the sequences of the murine antibody heavy and light chain constant regions were complemented in the variable region part and then sent to Mimetai and Inc., Beijing, for gene sequence synthesis and insect cell codon optimization. Constructing a shuttle vector: according to the sequence information of the heavy chain and the light chain and the sequence information of a pFastBacdual carrier, corresponding primers are designed, the full-length fragments of the heavy chain and the light chain are amplified, the recovered gel is connected into the pFastBacdual carrier through a homologous recombination method, wherein the pFastBacdual carrier contains two promoters, namely a PH promoter and a P10 promoter, and the sequence determination is carried out after the gel is connected into the carrier to ensure the accuracy of the sequence. Screening and extracting recombined Bacmid: the constructed punctureTransforming DH10Bac competence by using a shuttle vector, coating a three-antibody plate (kanamycin, gentamicin and tetracycline), culturing for 48h in an incubator at 37 ℃, picking out white spots, identifying by using a 1E103 primer, selecting clone shake bacteria completely without 300bp bands, extracting Bacmid by using an isopropanol precipitation method after 12h, and then determining the concentration by using Nanodrop. Rescue of recombinant baculovirus: density was 2X 10 before transfection⁶And (2) spreading SF9 cells on a six-hole plate, transfecting recombinant Bacmid according to the amount of 5 mu g and 2.5 mu g, wherein the using amount of a transfection reagent is 8 mu l, changing the liquid after 4-6 h of transfection, culturing at 28 ℃, harvesting and amplifying P2 generation virus after 72h, and amplifying the P3 generation virus by adopting the same method. The amplification of the P4 generation virus adopts shake flask amplification, and the inoculation ratio of the virus is 1: 100.

7) expression and purification of specific monoclonal antibodies: inoculating the P4 generation virus at a ratio of 1:5 with a density of 2 × 10⁶Hi5 cells, cultured at 28 ℃, harvested after 48h, centrifuged at 8000r/min for 1h to obtain the supernatant, and then filtered through a 0.22 μm filter for later use. With Na₃PO₄And (3) balancing the ProteinA prepacked column by using a solution with the pH value of 7.0, balancing the volume of 3-5 columns, then combining the cell supernatant with the ProteinA prepacked column, and eluting with an eluent with the pH value of 3.0 of Glycine-HCL after the sample is combined, thereby obtaining the purified specific monoclonal antibodies 5G11 and 1C10 of the foot-and-mouth disease type A (A/WH/09 strain).

Based on the monoclonal antibody, the enzyme linked immunosorbent assay kit for specifically and quantitatively detecting the foot-and-mouth disease A type Wuhan strain antigen can be prepared, the kit utilizes a monoclonal antibody 5G11 which can be specifically combined with the antigen of the foot-and-mouth disease A type Wuhan strain (A/WH/09 strain) 146S as a capture antibody, in addition, an enzyme-labeled antibody prepared from the monoclonal antibody 1C10 which can be specifically combined with the foot-and-mouth disease A type Wuhan strain (A/WH/09 strain) 146S antigen is used as a detection antibody, so that the method for detecting the foot-and-mouth disease A type Wuhan strain (A/WH/09 strain) 146S antigen with good specificity, sensitivity and repeatability is established, the kit is used for detecting the 146S antigen content of the foot-and-mouth disease A type Wuhan strain (A/WH/09 strain) in culture solution, inactivated solution, purified solution, concentrated solution, demulsified finished vaccine and the like in the vaccine production process.

Based on the purposes, the enzyme-linked immunosorbent assay kit for specifically and quantitatively detecting the antigen of the foot-and-mouth disease type A Wuhan strain comprises an enzyme-linked reaction plate prepared by taking a monoclonal antibody 5G11 capable of being specifically combined with the antigen 146S of the foot-and-mouth disease type A Wuhan strain (A/WH/09 strain) as a capture antibody, and an enzyme-labeled antibody prepared by taking a monoclonal antibody 1C10 capable of being specifically combined with the antigen 146S of the foot-and-mouth disease type A Wuhan strain (A/WH/09 strain) as a detection antibody. The enzyme-labeled antibody is preferably an antibody labeled by a horseradish-labeled enzyme, and the horseradish peroxidase can be crosslinked on the antibody by a glutaraldehyde method or a periodic acid method.

Preferably, the type A Wuhan strain of the foot-and-mouth disease is a type A Wuhan strain A/WH/09 strain of the foot-and-mouth disease.

The capture antibody (monoclonal antibody 5G11) contains the heavy chain variable region 5G11-V_HAnd light chain variable region 5G11-V_L(ii) a The 5G11-V_HAnd 5G11-V_LBoth consist of a determinant complementary region and a framework region; the 5G11-V_HAnd said 5G11-V_LEach of the determinant complementary regions of (a) consists of a CDR1, a CDR2 and a CDR 3; the 5G11-V_HThe amino acid sequence of the CDR1 is shown as amino acids 25 to 34 of SEQ ID No. 1; the 5G11-V_HThe amino acid sequence of the CDR2 is shown as amino acids 51-58 of SEQ ID No. 1; the 5G11-V_HThe amino acid sequence of the CDR3 is shown as amino acids 98-114 of SEQ ID No. 1; the 5G11-V_LThe amino acid sequence of the CDR1 is shown as amino acids 24-35 of SEQ ID No. 2; the 5G11-V_LThe amino acid sequence of the CDR2 is shown as amino acids 49-58 of SEQ ID No. 2; the 5G11-V_LThe amino acid sequence of the CDR3 is shown as amino acids 95-98 of SEQ ID No. 2;

the detection antibody (monoclonal antibody 1C10) contains a heavy chain variable region 1C10-V_HAnd light chain variable region 1C10-V_L1C10-V as described_HAnd 1C10-V_LBoth consist of a determinant complementary region and a framework region; the 1C10-V_HAnd said 1C10-V_LEach of the determinant complementary regions of (a) consists of a CDR1, a CDR2 and a CDR 3; the 1C10-V_HThe amino acid sequence of the CDR1 is shown as the amino acids at the 26 th to 36 th positions of SEQ ID No.3(ii) a The 1C10-V_HThe amino acid sequence of the CDR2 is shown as amino acids 54-61 of SEQ ID No. 3; the 1C10-V_HThe amino acid sequence of the CDR3 is shown as amino acids 98-111 of SEQ ID No. 3; the 1C10-V_LThe amino acid sequence of the CDR1 is shown as amino acids 24-36 of SEQ ID No. 4; the 1C10-V_LThe amino acid sequence of the CDR2 is shown as amino acids 50-59 of SEQ ID No. 4; the 1C10-V_LThe amino acid sequence of CDR3 is shown as amino acids 94-99 of SEQ ID No. 4.

Preferably, the 5G11-V_HThe amino acid sequence of (A) is shown as 1 st to 128 th sites of SEQ ID No.1 in a sequence table; its 5G11-V_LThe amino acid sequence of (A) is shown as 1 st to 115 th sites of SEQ ID No.2 in a sequence table;

preferably, the 1C10-V_HThe amino acid sequence of (A) is shown as 1 st to 127 th sites of SEQ ID No.3 in a sequence table; 1C10-V thereof_LThe amino acid sequence of (A) is shown as 1 st to 116 th sites of SEQ ID No.4 in the sequence table.

The optimal coating preparation method and conditions of the enzyme-linked reaction plate are that a specific monoclonal antibody 5G11 of the foot-and-mouth disease type A Wuhan strain (A/WH/09 strain) is diluted into 1-10 mu G/ml coating working solution by using a carbonate solution with pH of 9.6, then the coating working solution is added into a 96-hole polystyrene enzyme-linked reaction plate, 100 mu l/hole is placed for 8-12 hours at 2-8 ℃, so that the specific monoclonal antibody 5G11 is fully combined with the enzyme-linked reaction plate, then PBS buffer solution containing 10mg/ml bovine serum albumin pH7.4 is added into the 96-hole polystyrene enzyme-linked reaction plate according to 300 mu l/hole, the mixture is subjected to sealing treatment at 37 ℃ for 2-3 hours, and after the spin-drying, the enzyme-linked reaction plate is dried and is sealed and stored at 2-8 ℃.

Preferably, the kit also comprises an antigen standard substance, wherein the antigen standard substance is a foot-and-mouth disease type A Wuhan strain (A/WH/09 strain) 146S antigen, the purity is not lower than 80%, the antigen content is 4 mu g/ml, and the antigen standard substance is diluted to (3.1 ng/ml-200 ng/ml) by using a sample diluent when in use. The antigen content is 4 μ g/ml, and the antigen is diluted by sample diluent (1: 20-1: 1280) times when in use, and the measured OD_450nmValues were used to plot a standard curve.

The kit is a double-antibody sandwich enzyme-linked immunosorbent quantitative detection kit prepared by adopting a foot-and-mouth disease A/WH/09 strain specific monoclonal antibody, and the antigen content of the foot-and-mouth disease A/WH/09 strain in a sample is quantitatively detected by detecting the signal change generated by an enzyme catalytic substrate.

Furthermore, the kit also comprises a sample diluent, a 20-time concentrated washing solution, a substrate solution A, a substrate solution B and a stop solution. The enzyme-linked reaction plate is a detachable 96-hole enzyme label plate. The sample diluent was a phosphate buffer solution containing 5mg/ml casein and having a value of 0.01M, pH of 7.4. The 20-time concentrated washing solution is 0.01M phosphate buffer solution with the pH value of 7.4 and contains 0.8-1.2% (ml/ml) of Tween-20. The substrate solution A is a citrate phosphate buffer solution containing 0.06% (g/ml) of urea hydrogen peroxide, and the substrate solution B is a tetramethylbenzidine solution of 0.2mg/ml, and the two are mixed in a ratio of 1:1 when in use. The stop solution is a 2mol/L sulfuric acid solution.

The application of the enzyme linked immunosorbent assay kit in the specific quantitative detection of the foot-and-mouth disease A type Wuhan strain antigen also belongs to the protection scope of the invention.

The invention has the positive effects that: the invention provides a specific monoclonal antibody for quantitatively detecting a foot-and-mouth disease type A Wuhan strain (A/WH/09 strain). The monoclonal antibody can be prepared into an enzyme linked immunosorbent assay kit, has high sensitivity and good specificity, is convenient to operate, and can stably detect the antigen content and specificity of the foot-and-mouth disease A type Wuhan strain (A/WH/09 strain) to distinguish the foot-and-mouth disease A type Wuhan strain from other strains. The kit is a double-antibody sandwich enzyme-linked immunosorbent assay quantitative detection kit prepared by two specific monoclonal antibodies of a foot-and-mouth disease A type Wuhan strain (A/WH/09 strain), can quantitatively detect the content of the antigen of the foot-and-mouth disease A type Wuhan strain (A/WH/09 strain) in a sample by detecting the signal change generated by an enzyme catalytic substrate, and does not have cross reaction with other strains of the current foot-and-mouth disease such as A type AF/72, O/Mya98/XJ/2010 strain, OS/99 strain, OZK/93 strain and Asia 1 type JSL/06 strain.

In conclusion, the double-antibody sandwich enzyme-linked immunosorbent assay quantitative detection kit prepared by two specific monoclonal antibodies of the foot-and-mouth disease A type Wuhan strain (A/WH/09 strain) has high sensitivity and strong specificity, and can effectively distinguish and detect the content of the foot-and-mouth disease A type Wuhan strain (A/WH/09 strain) antigen in a sample. Meanwhile, the operation method can complete detection of 88 samples except for the antigen standard and the negative quality control hole within 1.5 hours at most, greatly shortens the detection period, generally can complete detection of about 5 samples by a sucrose density gradient method for 3 days, does not need an expensive ultracentrifuge, provides a more convenient and effective method for identification of infection of the foot-and-mouth disease type A Wuhan strain (A/WH/09 strain) and determination of antigen content, and has wide market prospect and good economic and social benefits.

Drawings

FIG. 1 is a schematic view of the loading of an enzyme-linked immunosorbent assay plate of the kit of the invention.

Detailed Description

The methods in the following examples are conventional methods unless otherwise specified.

The various biological materials described in the examples are obtained by way of experimental acquisition for the purposes of this disclosure and should not be construed as limiting the source of the biological material of the invention. In fact, the sources of the biomaterials used are wide and any biomaterials available without violating laws and ethical ethics can be used instead as suggested in the examples.

The embodiments are provided in order to provide detailed embodiments and specific procedures, which will help understanding of the present invention, but the scope of the present invention is not limited to the following embodiments.

Example 1 screening of hybridoma cell lines for A-type foot-and-mouth disease Wuhan Strain (A/WH/09 Strain) monoclonal antibody

The method comprises the following steps:

1) obtaining 146S antigen of a foot-and-mouth disease A type Wuhan strain (A/WH/09 strain) (provided by Zhongmu industries, Ltd.) by using a sucrose density gradient method, and adjusting the concentration of the antigen to 10 mu g/ml to be used as immunogen;

2) the immune animal is BALB/c mouse (purchased from Beijing Wittingle laboratory animal technology Co., Ltd.), the continuous immunization is carried out for 4 times, each time is 14 days, the multipoint subcutaneous immunization mode is adopted for the first 3 times, the intraperitoneal injection immunization mode is adopted for the 4 th time, and each mouse is injected with 10 mu g of 146S antigen;

3) 7 days after the last immunization, separating serum from tail blood of the mouse, detecting by indirect ELISA (enzyme-linked immunosorbent assay), when the titer is more than 1:50000, separating splenocytes of the immunized animal, fusing the splenocytes with myeloma cells SP2/0 with good growth state, and screening by using HAT selective culture medium to obtain hybridoma cells;

4) screening specific positive clones from the hybridoma cell supernatant by an indirect ELISA method to finally obtain 3 specific positive clones; the method comprises the following specific operation steps: dissolving 146S purified antigens (provided by Zhongmu Ming corporation) such as foot-and-mouth disease A type Wuhan strain (A/WH/09 strain), A type (AF/72 strain), O type Xinjiang strain (O/Mya98/XJ/2010 strain), O type OS/99 strain, O type OZK/93 strain, Asia type 1 (JSL/06 strain) and the like (146S purified antigens) in 100 mul of carbonate solution with pH of 9.6 to dilute the solution to 2 mul/ml, then adding the solution to a 96-hole polystyrene enzyme-linked reaction plate, placing the plate at 2-8 ℃ for 8-12 hours at 100 mul per hole to fully combine a specific monoclonal antibody with the enzyme-linked reaction plate, then adding PBS (phosphate buffer solution) containing 10mg/ml of bovine serum albumin (pH7.4) according to 300 mul/hole, sealing the plate at 37 ℃ for 2-3 hours, drying the plate, sealing the plate with aluminum foil paper after drying, and storing at 2-8 ℃ for later use.

Adding cell culture supernatant into an enzyme label plate coated with virus antigen, reacting for 30 minutes at 37 ℃, washing the plate for 4 times by using a washing solution (0.01M phosphate buffer solution with 0.8-1.2% (ml/ml) of Tween-20 and the pH value of 7.4, diluting 20 times by using double distilled water when in use), after drying, adding a rabbit anti-mouse IgG-HRP marker (purchased from Sigma company in America) diluted by 1:5000 into each hole, reacting for 30 minutes at 37 ℃, using the washing solution for 4 times, after drying, adding 50 mul of substrate working solution A (citrate phosphate buffer solution containing 0.6mg/ml of urea hydrogen peroxide) and substrate solution B (tetramethylbenzidine solution containing 0.2 mg/ml) into each hole, and reacting for 15 minutes at 37 ℃ in a dark place. Mu.l of stop solution (2mol/L sulfuric acid solution) was added to each well, and the reaction was terminated by shaking and mixing. OD per well was measured within 15 minutes_450nmThe value is obtained. Determining the special value of the cell culture supernatant by taking the absorbance value of more than negative control (namely plate washing culture solution) multiplied by 2.1 as a positive judgment standardThe titer of the specific monoclonal antibody is determined, whether the monoclonal antibody washing strain has cross reaction with other viruses is determined, and finally 3 specific cell clones are obtained, wherein the specific cell clones only have strong signal reaction with a hoof-and-mouth disease type A Wuhan strain (A/WH/09 strain) but do not react with strains such as type A (AF/72 strain), Xinjiang strain (O/Mya98/XJ/2010 strain), type O OS/99 strain, type O OZK/93 strain and Asia type 1 (JSL/06 strain), and the 3 strains are respectively numbered as 1C10, 3C6 and 5G 11. OD measurement with UV spectrophotometer_280nmValue using the OD_280nmThe value divided by an empirical factor of 1.48 is the concentration of the monoclonal antibody in mg/ml. The results showed that 1C10 secreted monoclonal antibody at a concentration of 1.1mg/ml, 3C6 secreted monoclonal antibody at a concentration of 0.9mg/ml, and 5G11 secreted monoclonal antibody at a concentration of 0.5 mg/ml.

Example 2 pairing test of monoclonal purified antibodies against the A-type foot-and-mouth disease Wuhan Strain (A/WH/09 Strain)

1) Preparation of coating plate with specific monoclonal antibody of A-type Wuhan strain of foot-and-mouth disease (A/WH/09 strain)

Diluting the purified specific monoclonal antibody into coating working solution of 0.5 mu g/ml, 1 mu g/ml, 2 mu g/ml and 4 mu g/ml by using carbonate solution with pH 9.6, then adding the coating working solution into a 96-hole polystyrene enzyme-linked reaction plate, placing the plate at 100 mu l/hole for 8-12 hours at 2-8 ℃ to ensure that the specific monoclonal antibody is fully combined with the enzyme-linked reaction plate, then adding PBS buffer solution containing 10mg/ml bovine serum albumin with pH7.4 into the plate according to 300 mu l/hole, sealing the plate at 37 ℃ for 2-3 hours, drying the plate, and sealing and storing the plate at 2-8 ℃ after the plate is dried.

2) Preparing horse radish peroxidase labeled Wuhan strain A type foot-and-mouth disease A (A/WH/09 strain) specific monoclonal antibody

Coupling a specific monoclonal antibody of a type A Wuhan strain (A/WH/09 strain) of foot-and-mouth disease with horseradish peroxidase (HRP) by glutaraldehyde oxidation, dialyzing thoroughly with PBS buffer solution of pH7.4, adding equal amount of high-quality glycerol, and storing at-20 deg.C or below. The method comprises the following specific steps:

dissolving 5mg of HRP in 0.2ml of PBS (phosphate buffer solution) containing 1.25% of glutaraldehyde and having the pH value of 6.8 of 0.1mol/L, placing the solution at room temperature for coupling for 18 hours, and fully dialyzing to remove redundant glutaraldehyde;

adding physiological saline to 1ml, adding 2.5mg of a specific monoclonal antibody of a purified foot-and-mouth disease A type Wuhan strain (A/WH/09 strain) and 0.1ml of 1mol/L carbonate buffer solution with the pH value of 9.6, and placing for 24 hours at the temperature of 2-8 ℃;

③ adding 0.1ml of 0.3mol/L lysine solution, and standing for 2 hours at room temperature;

and fourthly, fully dialyzing by using PBS buffer solution with the pH value of 7.4, and removing the precipitate through centrifugation to obtain the supernatant which is the enzyme conjugate. Diluting with enzyme marker diluent according to a certain proportion (1:1000, 1:2000 and 1:4000 times dilution) to obtain the working solution of the enzyme marker.

3) Pairing test between three specific antibodies a checkerboard titration was used to determine the pairing pattern between 3 monoclonal antibodies (1C10, 3C6, 5G 11).

Adding 146S antigen: diluting 146S antigen with a sample diluent, wherein one part of the antigen is 100ng/ml, the other part of the antigen is 10ng/ml, and the concentration of the antigen is 100 mu l/hole, and reacting for 30 minutes at 37 ℃;

adding enzyme labeled single antibody: after washing the plate for 4 times continuously, adding enzyme-labeled monoclonal antibody (1C10, 3C6, 5G11), and reacting for 30 minutes at 37 ℃;

③ developing color: continuously washing the plate for 4 times, adding 100 μ l of substrate working solution (substrate working solution is obtained by mixing substrate solution A and substrate solution B in equal amount, and is prepared in situ), shaking, mixing, placing in 37 deg.C incubator, and reacting in dark place for 15 min;

reading: 50. mu.l of chromogenic stop solution was added to each well, and the reaction was stopped by shaking and mixing. Determination of OD per well_450nmThe value is obtained. OD with 100ng/ml sample_450nmValue (A) divided by OD of 10ng/ml sample_450nmThe larger the value (B), the larger the A/B value, the higher the detection sensitivity of the conjugated monoclonal antibody, and the results are shown in Table 1-Table 3, therefore, 5G11 is preferred as the capture antibody, 1C10 is preferred as the detection antibody, wherein 5G11 can be selected as the capture antibody at 1. mu.g/ml, and 1C10 can be selected as the detection antibody at 1:2000 dilution.

TABLE 1 results of the pairing test with 1C10 as capture antibody (A/B values)

TABLE 2 results of the pairing test with 3C6 as capture antibody (A/B values)

TABLE 3 results of the pairing test with 5G11 as capture antibody (A/B values)

Example 3 Gene sequencing of specific hybridoma cell line of A-type foot-and-mouth disease Wuhan Strain A (A/WH/09 Strain) monoclonal antibody and establishment of monoclonal antibody recombinant expression System

The method comprises the following steps:

1) extracting total RNA of a specific positive clone hybridoma cell strain, performing reverse transcription, performing PCR (polymerase chain reaction) and performing sequence determination:

extracting total RNA: taking 250 ul of hybridoma cell suspension, adding 750 ul of Trizol, turning upside down and mixing, adding 200 ul of chloroform, mixing, and centrifuging at 12000rpm at 4 ℃ for 15 min. The supernatant was pipetted into a new 1.5ml EP tube, 600. mu.l of isopropanol was added, mixed well and centrifuged for 10 min. The isopropanol was discarded, washed with 75% DEPC ethanol and centrifuged. The ethanol was discarded, oven dried and the RNA was dissolved in 20. mu.l of RNase-free water.

Reverse transcription: reverse transcription was performed using the Invitrogen reverse transcription kit as per the instructions to obtain cDNA for hybridoma cells.

PCR reaction and cloning and sequencing of products thereof: universal primers were designed for the heavy and light chain variable regions with the following sequence information:

TABLE 4 Universal primers for heavy and light chain variable regions

And amplifying the target fragment by using an amplification primer, recovering the fragment after amplification, and then connecting a vector for sequence determination to obtain sequence information of heavy chain and light chain variable regions of the monoclonal antibody.

Monoclonal antibody 5G11 contains heavy chain variable region 5G11-V_HAnd light chain variable region 5G11-V_L(ii) a The 5G11-V_HAnd 5G11-V_LBoth consist of a determinant complementary region and a framework region; 5G11-V_HThe amino acid sequence of (A) is shown as 1 st to 128 th sites of SEQ ID No.1 in a sequence table; its 5G11-V_LThe amino acid sequence of (A) is shown as 1 st to 115 th sites of SEQ ID No.2 in a sequence table;

the 5G11-V_HAnd said 5G11-V_LEach of the determinant complementary regions of (a) consists of a CDR1, a CDR2 and a CDR 3; the 5G11-V_HThe amino acid sequence of the CDR1 is shown as amino acids 25 to 34 of SEQ ID No. 1; the 5G11-V_HThe amino acid sequence of the CDR2 is shown as amino acids 51-58 of SEQ ID No. 1; the 5G11-V_HThe amino acid sequence of the CDR3 is shown as amino acids 98-114 of SEQ ID No. 1; the 5G11-V_LThe amino acid sequence of the CDR1 is shown as amino acids 24-35 of SEQ ID No. 2; the 5G11-V_LThe amino acid sequence of the CDR2 is shown as amino acids 49-58 of SEQ ID No. 2; the 5G11-V_LThe amino acid sequence of the CDR3 is shown as amino acids 95-98 of SEQ ID No. 2;

monoclonal antibody 1C10 contains heavy chain variable region 1C10-V_HAnd light chain variable region 1C10-V_L1C10-V as described_HThe amino acid sequence of (A) is shown as 1 st to 127 th sites of SEQ ID No.3 in a sequence table; 1C10-V thereof_LThe amino acid sequence of (A) is shown as 1 st to 116 th sites of SEQ ID No.4 in the sequence table.

The 1C10-V_HAnd 1C10-V_LBoth consist of a determinant complementary region and a framework region; the 1C10-V_HAnd station1C10-V_LEach of the determinant complementary regions of (a) consists of a CDR1, a CDR2 and a CDR 3; the 1C10-V_HThe amino acid sequence of the CDR1 is shown as amino acids 26-36 of SEQ ID No. 3; the 1C10-V_HThe amino acid sequence of the CDR2 is shown as amino acids 54-61 of SEQ ID No. 3; the 1C10-V_HThe amino acid sequence of the CDR3 is shown as amino acids 98-111 of SEQ ID No. 3; the 1C10-V_LThe amino acid sequence of the CDR1 is shown as amino acids 24-36 of SEQ ID No. 4; the 1C10-V_LThe amino acid sequence of the CDR2 is shown as amino acids 50-59 of SEQ ID No. 4; the 1C10-V_LThe amino acid sequence of CDR3 is shown as amino acids 94-99 of SEQ ID No. 4.

2) Synthesis of gene sequence of specific monoclonal antibody and establishment of recombinant expression system

Synthesis of gene sequence: according to the determined sequences of the heavy chain and light chain variable regions of the monoclonal antibodies 5G11 and 1C10, sequences of the heavy chain and light chain constant regions of a mouse antibody are supplemented in a variable region part, then the variable region part is sent to Meitai company in Beijing to synthesize a gene sequence, and insect cell codon optimization is carried out, wherein the nucleotide sequence of the 5G11 heavy chain is shown as SEQ ID No.5 (the full-length sequence is the coding sequence) in a sequence table, and the nucleotide sequence of the 5G11 light chain is shown as SEQ ID No.6 (the full-length sequence is the coding sequence) in the sequence table; the nucleotide sequence of the 1C10 heavy chain is shown as SEQ ID No.7 (the full-length sequence is the coding sequence) in the sequence table, and the nucleotide sequence of the 1C10 light chain is shown as SEQ ID No.8 (the full-length sequence is the coding sequence) in the sequence table.

Constructing a shuttle vector: according to the sequence information of the heavy chain and the light chain and the sequence information of a pFastBacdual vector (purchased from Thermo Fisher company, Cat. 10712024), corresponding primers are designed (the sequences are shown in the following table 5), fragments of the full length of the heavy chain and the light chain are amplified, the fragments are connected into the pFastBacdual vector through a homologous recombination method after the gel is recovered, wherein the pFastBacdual vector contains two promoters, namely a PH promoter and a P10 promoter, and the sequence determination is carried out after the fragments are connected into the vector to ensure the accuracy of the sequences.

TABLE 5 expression vector construction primer sequence information

Screening and extracting recombined Bacmid: transforming DH10Bac competence by the constructed shuttle vector, coating a three-resistance plate (kanamycin, gentamicin and tetracycline), culturing for 48h at 37 ℃ in an incubator, picking out white spots, identifying by using an M13 primer, selecting clone shake bacteria completely without 300bp bands, extracting Bacmid by using an isopropanol precipitation method after 12h, and then determining the concentration by using Nanodrop.

Rescue of recombinant baculovirus: density was 2X 10 before transfection⁶And (2) spreading SF9 cells on a six-hole plate, transfecting recombinant Bacmid according to the amount of 5 mu g and 2.5 mu g, wherein the using amount of a transfection reagent is 8 mu l, changing the liquid after 4-6 h of transfection, culturing at 28 ℃, harvesting and amplifying P2 generation virus after 72h, and amplifying the P3 generation virus by adopting the same method. The amplification of the P4 generation virus adopts shake flask amplification, and the inoculation ratio of the virus is 1: 100.

6) expression and purification of specific monoclonal antibodies: inoculating the P4 generation virus at a ratio of 1:5 with a density of 2 × 10⁶Hi5 cells, cultured at 28 ℃, harvested after 48h, centrifuged at 8000r/min for 1h to obtain the supernatant, and then filtered through a 0.22 μm filter for later use. With Na₃PO₄And (3) balancing the ProteinA prepacked column by using a solution with the pH value of 7.0, balancing the volume of 3-5 columns, then combining the cell supernatant with the ProteinA prepacked column, and eluting with an eluent with the pH value of 3.0 of Glycine-HCL after the sample is combined, thereby obtaining the purified specific monoclonal antibodies 5G11, 3C6 and 1C10 of the foot-and-mouth disease A type Wuhan strain (A/WH/09 strain). OD measurement with UV spectrophotometer_280nmValue using the OD_280nmThe value divided by an empirical factor of 1.48 is the concentration of the monoclonal antibody in mg/ml. The results showed that the concentration of monoclonal antibody secreted by purified 1C10 was 4.2mg/ml, and that the monoclonal antibody secreted by 3C6 was monoThe concentration of the cloned antibody is 3.78mg/ml, and the concentration of the monoclonal antibody secreted by 5G11 is 1.78 mg/ml.

Example 4 preparation of foot-and-mouth disease type A Wuhan Strain (A/WH/09 Strain) antigen quantitative determination ELISA kit

1) Preparation of antigen coating plate by using specific monoclonal antibody of A-type Wuhan strain (A/WH/09 strain) of foot-and-mouth disease

Diluting the purified specific monoclonal antibody into coating working solution of 0.5 mu g/ml, 1 mu g/ml, 2 mu g/ml and 4 mu g/ml by using carbonate solution with pH 9.6, then adding the coating working solution into a 96-hole polystyrene enzyme-linked reaction plate, placing the plate at 100 mu l/hole for 8-12 hours at 2-8 ℃ to ensure that the specific monoclonal antibody is fully combined with the enzyme-linked reaction plate, then adding PBS buffer solution containing 10mg/ml bovine serum albumin with pH7.4 into the plate according to 300 mu l/hole, sealing the plate at 37 ℃ for 2-3 hours, drying the plate, and sealing and storing the plate at 2-8 ℃ after the plate is dried.

2) Preparing horse radish peroxidase labeled Wuhan strain A type foot-and-mouth disease A (A/WH/09 strain) specific monoclonal antibody

Coupling a specific monoclonal antibody of a type A Wuhan strain (A/WH/09 strain) of foot-and-mouth disease with horseradish peroxidase (HRP) by glutaraldehyde oxidation, dialyzing thoroughly with PBS buffer solution of pH7.4, adding equal amount of high-quality glycerol, and storing at-20 deg.C or below. The method comprises the following specific steps:

dissolving 5mg of HRP in 0.2ml of PBS (phosphate buffer solution) containing 1.25% of glutaraldehyde and having the pH value of 6.8 of 0.1mol/L, placing the solution at room temperature for coupling for 18 hours, and fully dialyzing to remove redundant glutaraldehyde;

adding physiological saline to 1ml, adding 2.5mg of a specific monoclonal antibody of a purified foot-and-mouth disease A type Wuhan strain (A/WH/09 strain) and 0.1ml of 1mol/L carbonate buffer solution with the pH value of 9.6, and placing for 24 hours at the temperature of 2-8 ℃;

③ adding 0.1ml of 0.3mol/L lysine solution, and standing for 2 hours at room temperature;

and fourthly, fully dialyzing by using PBS buffer solution with the pH value of 7.4, and removing the precipitate through centrifugation to obtain the supernatant which is the enzyme conjugate. Diluting the solution with an enzyme marker diluent according to a certain proportion to obtain the working solution of the enzyme marker.

3) Preparing foot-and-mouth disease type A Wuhan strain (A/WH/09 strain) antigen standard product

In order to facilitate result analysis, the kit further comprises an antigen standard of a foot-and-mouth disease type A Wuhan strain (A/WH/09 strain), specifically a 146S antigen purification solution of the foot-and-mouth disease type A Wuhan strain (A/WH/09 strain) produced by a foot-and-mouth disease vaccine factory, the purity of the antigen purification solution is not lower than 80%, the antigen content is 4 mug/ml, the antigen purification solution is subpackaged into 1.0 ml/tube, the sample dilution solution is diluted by a factor of (1: 20-1: 1280) when the kit is used, a label is pasted, and the kit is stored at the temperature of below-20 ℃ for later use.

4) The sample dilutions were prepared as 1 vial (24 ml/vial) of 0.01M, pH value 7.4 phosphate buffer containing 5mg/ml casein.

5) Substrate solution A was prepared as citrate phosphate buffer containing 0.6mg/ml urea hydrogen peroxide (1 vial, 12 ml/vial)

6) Substrate solution B was prepared as a 0.2mg/ml solution of Tetramethylbenzidine (TMB) (1 vial, 12 ml/vial).

7) The 20-fold concentrated washing solution was prepared as 0.01M phosphate buffer (50 ml/vial, 2 vials) containing Tween-20 at a concentration of 0.8% to 1.2% (ml/ml) and a pH of 7.4.

8) Preparation of stop solution A2 mol/L sulfuric acid solution (1 vial, 12 ml/vial) was prepared.

9) If necessary, the kit may also contain a sample dilution plate (2, 96 wells/block) for sample dilution.

Example 5 application method of enzyme-linked immunosorbent assay kit for quantitative detection of foot-and-mouth disease type A Wuhan strain (A/WH/09 strain) antigen

1) Balancing: taking out the kit from the refrigeration environment, and standing at room temperature for balancing for 30min for later use; the liquid reagents were mixed well before use.

2) Preparing liquid: diluting the concentrated washing solution by 20 times of distilled water or deionized water to obtain a washing buffer solution;

3) sample dilution: the antigen standard substance is serially diluted by 1: 20-1: 1280 times by using a sample diluent, the corresponding antigen concentrations are respectively 200ng/ml, 100ng/ml, 50ng/ml, 25ng/ml, 12.5ng/ml, 6.2ng/ml and 3.1ng/ml, and a sample to be detected is also subjected to 4-8 gradient dilution by using the sample diluent.

4) Sample adding: and taking out the required laths, filling the rest laths into an aluminum foil bag, sealing, and storing at 2-8 ℃ for later use. And adding the diluted sample to be detected and the serially diluted antigen standard into a coated plate, setting 1 hole as negative quality control at 100 mu l/hole, and only adding the sample diluent. The time span of the sample application process should be as short as possible. As shown in fig. 1, the sample application: S1-S7: diluting an antigen standard substance at a ratio of 1: 20-1: 1280, wherein N: indicating a negative quality control hole, and only adding a sample diluent; t1: indicating the addition of each sample to be tested.

5) And (3) incubation: shaking and mixing evenly, placing in an incubator at 37 ℃ and reacting for 30 min.

6) Washing the plate: discarding the reaction solution, adding 300 μ l of diluted washing buffer solution into each well, soaking for 15s, throwing away the washing solution, continuously washing the plate for 4 times, and then drying by beating.

7) Adding an enzyme: add 100. mu.l of enzyme-labeled antibody to each well.

8) And (3) incubation: the reaction mixture was placed in an incubator at 37 ℃ and reacted for 30 min.

9) Washing the plate: discarding the reaction solution, adding 300 mu l of diluted washing buffer solution into each hole, soaking for 15s, throwing away the washing solution, continuously washing the plate for 4 times, and then drying by beating.

10) Adding 100 μ l of substrate working solution (substrate working solution is obtained by mixing substrate solution A and substrate solution B in equal amount, and is prepared at present), shaking, mixing, placing in 37 deg.C incubator, and reacting for 15min in dark.

11) 50. mu.l of chromogenic stop solution was added to each well, and the reaction was stopped by shaking and mixing.

12) Determination of OD per well_450nmValue (reaction plate with stop solution should read OD within 15min_450nmValue).

13) And (4) analyzing results: antigen Standard (200ng/ml) well OD_450nmThe value should be more than or equal to 2.0, otherwise invalid; negative quality control hole OD_450nmThe value should be less than or equal to 0.15, otherwise invalid; and (3) calculating the concentration: OD of each well according to antigen standard_450nmDrawing a standard curve according to the value, and calculating the content of the foot-and-mouth disease type A Wuhan strain (A/WH/09 strain) in each sample to be detected.

In the above detection method, the sample to be detected may be selected variously, such as biopsy of animals infected by a type a hoof-and-mouth disease wuhan strain (a/WH/09 strain), virus solution obtained after cell culture, and the like, and culture solution, inactivated solution, purified solution, concentrated solution, and finished vaccine after emulsion breaking in the vaccine production process.

The result analysis method in step 13) may be: detecting each dilution OD of the well by using antigen standard_450nmValue and negative quality control well OD_450nmThe values were taken as the X-axis, the protein concentration was taken as the Y-axis, and an EXCEL program was used, → "insert" → "scatter plot", and "scatter plot with smooth line and data mark" → "trend line" → selection of "polynomial" → "display formula" and "display R square value". In general R²A value of 0.98 or more indicates that the standard curve is authentic (where points with too high or too low an OD should be discarded). Each 96-well plate should be set with a set of standards and plotted with the corresponding standard curve. Sample well OD according to polynomial equation_450nmAnd carrying out value substitution calculation to obtain the antigen concentration in the sample.

The detection process takes about 1.5 hours, and up to 88 samples can be detected in one experiment.

Example 6 repeatability test

1. In-batch repeatability test

The antigen standard of the foot-and-mouth disease type A Wuhan strain (A/WH/09 strain) 146S was diluted in a sample diluent in a double ratio (1: 20-1: 320) with 8-well repetition for each dilution, and OD was measured in the same experiment according to the kit of example 3 and the detection method of example 4_450nmValue, calculate the in-batch reproducibility of the kits of the invention.

The results are shown in Table 6, and it can be seen that the kit of the invention has an in-batch repeatability of between 6.0% and 13.6%, all of which are less than 15%, and the in-batch repeatability is good, and the detection result is stable and reliable.

TABLE 6 repeatability test in batches

2. Batch to batch repeatability test

With sample dilutionPerforming multiple dilution (1: 20-1: 320) on an antigen standard substance of a foot-and-mouth disease type A Wuhan strain (A/WH/09 strain) 146S, selecting 1 test strip of each of 3 different batches of kits, and determining OD (optical density) according to the kit of example 3 and the detection method of example 4_450nmValues, the batch-to-batch reproducibility of the kits of the invention was calculated.

The results show (Table 7), it can be seen that the kit of the invention has the repeatability within 5.1-14.3%, all less than 15%, the repeatability within batches is better, and the detection result is stable and reliable.

TABLE 7 repeatability tests between batches

Dilution factor	Theoretical concentration	Average value of detection	SD	Coefficient of variation CV
					1:20	200ng/ml	204.5	10.4	5.1
1:40	100ng/ml	106.4	6.9	6.5
					1:80	50ng/ml	51.7	3.9	7.5
1:160	25ng/ml	25.2	3.6	14.3
					1:320	12.5ng/ml	12.9	1.8	14.0

Example 7 sensitivity test

3 batches of the kit are selected, 100 mu l/hole of sample diluent is used, 8 holes are repeated, the kit of the embodiment 3 and the detection method of the embodiment 4 are used for detection, the average value (X) +3 multiplied by the Standard Deviation (SD) is calculated to be the detection sensitivity of the kit, and the maximum value is taken as the sensitivity of the kit.

TABLE 8 sensitivity test

Kit lot	Mean value (X)	Standard Deviation (SD)	X+3SD
				1	0.95	0.091	1.22
2	1.22	0.067	1.42
				3	1.15	0.119	1.50

The results of 3 replicates (labeled 8) showed that the sensitivity of the kit was 1.5ng/ml, but less than this sensitivity could be detected with the kit.

Example 8 specificity test

BHK21 cell host protein, A type (A/WH/09 strain) 146S antigen, A type (AF/72 strain) 146S antigen, foot-and-mouth disease O type Xinjiang strain (O/Mya98/XJ/2010 strain) 146S antigen, O type OS/99 strain 146S antigen, O type OZK/93 strain 146S antigen and Asia type 1 (JSL/06 strain) 146S antigen are selected, diluted to 2 mu g/ml by using sample diluent in the kit, the kit of the embodiment 3 and the detection method of the embodiment 4 are used for detection, meanwhile, negative quality control holes are arranged (only the sample diluent is added), the detection result shows that the antibody used by the kit has very high specificity and can be completely used for typing different serotypes of the foot-and-mouth disease, namely, the A type can be distinguished from the O type and the Asia type 1, and the A type can also be distinguished from different strains, the A/WH/09 strain can be distinguished from other strains of type A.

Example 8 comparison of the kit of the invention and its detection method with sucrose density gradient centrifugation method

In order to verify the accuracy and convenience of the detection result of the invention, a comparative test is carried out with a sucrose density gradient centrifugation method. The patent kit and sucrose density gradient centrifugation are used for simultaneously detecting 3 parts of A/WH/09 strain samples. As shown in table 9, the results of the two detection methods were high in coincidence rate, and the correlation coefficient R2 was 0.98 by fitting a trend line using EXCEL.

TABLE 9 comparative test results of the present kit and sucrose density gradient centrifugation method

Sample numbering	The kit (mu g/ml)	Sucrose density gradient centrifugation (μ g/ml)
			1	31.8	35.6
2	102.9	100.4
			3	19.6	20.1

Meanwhile, in the aspect of convenience in operation, the whole operation of the kit only needs 1.5 hours, 88 samples can be detected at most, expensive instruments and equipment are not needed, a sucrose density gradient centrifugation method needs 72 hours, each ultracentrifuge can only detect 5 samples, and the efficiency of quantitative detection of the foot-and-mouth disease 146S antigen is influenced.

Claims (6)

1. The monoclonal antibody can be specifically combined with the Wuhan strain 146S antigen of the foot-and-mouth disease A type and is any one of the following monoclonal antibodies:

1) comprises a heavy chain variable region 5G11-VH and a light chain variable region 5G 11-VL; the 5G11-VH and 5G11-VL each consist of a determinant complementary region and a framework region;

the determinant complementary regions of the 5G11-VH and the 5G11-VL each consist of a CDR1, a CDR2 and a CDR 3;

the amino acid sequence of the CDR1 of the 5G11-VH is shown as amino acids 25-34 of SEQ ID No. 1;

the amino acid sequence of the CDR2 of the 5G11-VH is shown as amino acids 51-58 of SEQ ID No. 1;

the amino acid sequence of the CDR3 of 5G11-VH is shown as amino acids 98-114 of SEQ ID No. 1;

the amino acid sequence of the CDR1 of 5G11-VL is shown as amino acids 24-35 of SEQ ID No. 2;

the amino acid sequence of the CDR2 of 5G11-VL is shown as amino acids 49-58 of SEQ ID No. 2;

the amino acid sequence of the CDR3 of 5G11-VL is shown as amino acids 95-98 of SEQ ID No. 2;

2) comprises a heavy chain variable region 1C10-VH and a light chain variable region 1C10-VL, wherein each of the 1C10-VH and 1C10-VL comprises a determinant complementary region and a framework region;

the determinant complementarity regions of the 1C10-VH and the 1C10-VL each consist of CDR1, CDR2 and CDR 3;

the amino acid sequence of the CDR1 of 1C10-VH is shown as amino acids 26-36 of SEQ ID No. 3;

the amino acid sequence of the CDR2 of 1C10-VH is shown as amino acids 54-61 of SEQ ID No. 3;

the amino acid sequence of the CDR3 of 1C10-VH is shown as amino acids 98-111 of SEQ ID No. 3;

the amino acid sequence of the CDR1 of 1C10-VL is shown as amino acids 24-36 of SEQ ID No. 4;

the amino acid sequence of the CDR2 of 1C10-VL is shown as amino acids 50-59 of SEQ ID No. 4;

the amino acid sequence of the CDR3 of 1C10-VL is shown as amino acids 94-99 of SEQ ID No. 4.

2. The monoclonal antibody of claim 1, wherein 1) the monoclonal antibody comprises the heavy chain variable region 5G11-VH and the light chain variable region 5G 11-VL; the amino acid sequence of the 5G11-VH is shown as the 1 st to 128 th sites of SEQ ID No.1 in the sequence table; the amino acid sequence of 5G11-VL is shown as 1 st to 115 th sites of SEQ ID No.2 in a sequence table;

2) the monoclonal antibody comprises a heavy chain variable region 1C10-VH and a light chain variable region 1C10-VL, wherein the amino acid sequence of the 1C10-VH is shown as the 1 st to 127 th sites of SEQ ID No.3 in a sequence table; the amino acid sequence of 1C10-VL is shown as 1 st to 116 th of SEQ ID No.4 in the sequence table.

3. A monoclonal antibody composition comprising the monoclonal antibodies of 1) and 2) below; 1) comprises a heavy chain variable region 5G11-VH and a light chain variable region 5G 11-VL; the 5G11-VH and 5G11-VL each consist of a determinant complementary region and a framework region; it can be specifically combined with the foot-and-mouth disease A type Wuhan strain 146S antigen;

the determinant complementary regions of the 5G11-VH and the 5G11-VL each consist of a CDR1, a CDR2 and a CDR 3;

the amino acid sequence of the CDR1 of the 5G11-VH is shown as amino acids 25-34 of SEQ ID No. 1;

the amino acid sequence of the CDR2 of the 5G11-VH is shown as amino acids 51-58 of SEQ ID No. 1;

the amino acid sequence of the CDR3 of 5G11-VH is shown as amino acids 98-114 of SEQ ID No. 1;

the amino acid sequence of the CDR1 of 5G11-VL is shown as amino acids 24-35 of SEQ ID No. 2;

the amino acid sequence of the CDR2 of 5G11-VL is shown as amino acids 49-58 of SEQ ID No. 2;

the amino acid sequence of the CDR3 of 5G11-VL is shown as amino acids 95-98 of SEQ ID No. 2;

2) comprises a heavy chain variable region 1C10-VH and a light chain variable region 1C10-VL, wherein each of the 1C10-VH and 1C10-VL comprises a determinant complementary region and a framework region; it can be specifically combined with the foot-and-mouth disease A type Wuhan strain 146S antigen;

the determinant complementarity regions of the 1C10-VH and the 1C10-VL each consist of CDR1, CDR2 and CDR 3;

the amino acid sequence of the CDR1 of 1C10-VH is shown as amino acids 26-36 of SEQ ID No. 3;

the amino acid sequence of the CDR2 of 1C10-VH is shown as amino acids 54-61 of SEQ ID No. 3;

the amino acid sequence of the CDR3 of 1C10-VH is shown as amino acids 98-111 of SEQ ID No. 3;

the amino acid sequence of the CDR1 of 1C10-VL is shown as amino acids 24-36 of SEQ ID No. 4;

the amino acid sequence of the CDR2 of 1C10-VL is shown as amino acids 50-59 of SEQ ID No. 4;

the amino acid sequence of the CDR3 of 1C10-VL is shown as amino acids 94-99 of SEQ ID No. 4.

4. The monoclonal antibody composition of claim 3, wherein said monoclonal antibody composition consists of the following monoclonal antibodies 1) and 2):

1) comprises a heavy chain variable region 5G11-VH and a light chain variable region 5G 11-VL; the amino acid sequence of the 5G11-VH is shown as the 1 st to 128 th sites of SEQ ID No.1 in the sequence table; the amino acid sequence of 5G11-VL is shown as 1 st to 115 th sites of SEQ ID No.2 in a sequence table;

2) the light chain variable region comprises a heavy chain variable region 1C10-VH and a light chain variable region 1C10-VL, wherein the amino acid sequence of the 1C10-VH is shown as the 1 st to 127 th sites of SEQ ID No.3 in a sequence table; the amino acid sequence of 1C10-VL is shown as 1 st to 116 th of SEQ ID No.4 in the sequence table.

5. Use of the monoclonal antibody of claim 1 or 2 for the preparation of a kit for the detection of foot-and-mouth disease antigens.

6. Use of the monoclonal antibody composition of claim 3 or 4 for the preparation of a kit for the detection of foot and mouth disease antigens.

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