1. A cell line for the sustained and stable production of bovine viral diarrhea virus antigen, wherein said cell line is prepared according to the following method: inoculating bovine viral diarrhea virus to sensitive cell line, screening persistent infected cells by limiting dilution method, cloning, purifying, and determining virus titer to be higher than 10^7.0TCID₅₀Establishing a cell line to obtain a cell line continuously infecting the bovine viral diarrhea virus;

the sensitive cell line is one of MDBK cell line, BT cell line, PT cell line, ST cell line, PK cell line, CRFK cell line, F81 cell line and MDCK cell line.

2. The cell line of claim 1, wherein the clones are purified 3 or more times.

3. The cell line of claim 1, wherein persistence of the virus is determined by immunofluorescence after each clonal purification.

4. The cell line of claim 1, wherein the bovine viral diarrhea virus is ncp-type bovine viral diarrhea virus and the virus droplets areDegree higher than 10^7.0TCID₅₀。

5. The cell line according to any one of claims 1 to 4, wherein the preservation number of the cell line persistently infected with bovine viral diarrhea virus is CGMCCNo.22351.

6. A preparation method of a colloidal gold test strip for detecting bovine viral diarrhea virus antibodies is characterized by comprising the following steps:

A) performing amplification culture on the cell line of any one of claims 1 to 5, harvesting cell culture supernatant and cells, performing freeze thawing for 2-3 times repeatedly, and performing differential centrifugation and PEG precipitation to obtain a purified bovine viral diarrhea virus antigen;

B) performing first coupling on the bovine viral diarrhea virus antigen and the colloidal gold to obtain a bovine viral diarrhea virus antigen-colloidal gold coupling marker;

performing second coupling on the IgG and the colloidal gold to obtain an IgG-colloidal gold coupled marker;

C) respectively spraying the bovine viral diarrhea virus antigen-colloidal gold conjugate marker and the IgG-colloidal gold conjugate marker on a glass cellulose membrane, and drying to obtain a gold-labeled binding pad;

respectively scratching bovine viral diarrhea virus antigen and IgG on a detection line and a quality control line on a nitrocellulose membrane;

D) and (3) sequentially sticking the sample pad, the gold-labeled binding pad, the nitrocellulose membrane and the absorption pad on the bottom plate, cutting, assembling and sealing to obtain the colloidal gold test strip for the bovine viral diarrhea virus antibody.

7. The method according to claim 6, wherein the colloidal gold has a particle size of 40 to 60 nm.

8. The preparation method of claim 6, wherein the ratio of the bovine viral diarrhea virus antigen to the colloidal gold solution is 30-40 μ g:1mL in the first coupling.

9. The method of claim 6, wherein the ratio of IgG to colloidal gold solution used in the second coupling is 3.5-4.5 μ g/1 mL.

10. The method of any one of claims 6 to 9, wherein the IgG of step B) is mouse IgG and the IgG of step C) is goat anti-mouse IgG.

Background

Bovine Viral Diarrhea Virus (BVDV), also known as Bovine Viral Diarrhea/mucosal Virus, is an important member of the genus pestivirus of the family flaviviridae, and has cross-reactivity with border viruses of swine fever Virus and sheep in serological tests. BVDV is an important pathogen widely popularized and seriously harming the breeding industry in the world, and viruses can infect various animals such as cattle, sheep, pigs and the like. BVDV infection causes a huge economic loss to the breeding industry, ranging from $ 2000 to $ 5700 million in the united states per 100 million calves. In China, the first BVDV was isolated and identified in 1983 by Li Yongmin. Since this time, more than 20 provinces, cities and autonomous regions in Xinjiang, Nemeng, Jilin, Heilongjiang, Henan, Shandong, Liaoning, etc. of China all detected the disease, and the positive rate of individual regions is more than 85%. Because no good immune protection measures exist, the disease is in an ascending trend, the influence on fattening, milk production and reproduction of cattle is great, and serious harm is caused to the cattle industry. Infection with BVDV can cause a variety of clinical conditions, including respiratory, reproductive, and immunosuppression. Can also create conditions for other pathogens to infect animals to cause secondary infection, so that the harm to the cattle group is not negligible.

BVDV is classified into two biotypes, cytopathic (cp) and non-cytopathic (ncp), depending on whether the inoculated cells produce cytopathic effects (CPE). Clinically isolated strains are mostly non-cytopathic variants. The ncpBVDV often infects cells with contaminating bovine serum, resulting in persistent bovine viral diarrhea virus infection of the cells.

Bovine serum is an important raw material for research and development of biological products and medical research, and the bovine serum containing bovine viral diarrhea virus antibodies can affect the production of other virus vaccines of the same family, such as classical swine fever virus. Serum containing antibodies to bovine viral diarrhea virus severely reduced the titer of swine fever vaccine. Therefore, serum is collected from cow to cow. At present, the conventional serum neutralization experimental method has complex and time-consuming detection steps, needs professional personnel for operation and mainly depends on a laboratory. The commercialized kit for detecting the virus antibody is mainly an imported kit, is expensive, needs professional operation and a precise instrument (enzyme-linked immunosorbent assay) and cannot meet the actual requirements of a basic level, and the popularization and the promotion of the detection of the bovine viral diarrhea are seriously hindered. Therefore, the research on a simple and quick bovine viral diarrhea virus antibody detection method has very important significance.

Disclosure of Invention

In view of this, the invention provides a cell line for stably producing bovine viral diarrhea virus antigen and a preparation method of an antibody colloidal gold test strip. The cell line does not need to inoculate virus seeds, and can save the use amount of the virus seeds according to the passage of normal cells, avoid the problems of complex operation, easy pollution and the like, and save manpower and material resources.

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

the invention provides a cell line for continuously and stably producing bovine viral diarrhea virus antigen, which is prepared according to the following method: inoculating bovine viral diarrhea virus to sensitive cell line, screening persistent infected cells by limiting dilution method, cloning, purifying, and determining virus titer to be higher than 10^7.0TCID₅₀Establishing a cell line to obtain a cell line which continuously and stably generates the bovine viral diarrhea virus antigen;

the sensitive cell line is one of MDBK cell line, BT cell line, PT cell line, ST cell line, PK cell line, CRFK cell line, F81 cell line and MDCK cell line.

Preferably, the number of cloning and purification is 3 or more.

In the specific example provided by the present invention, the number of cloning purifications was 3.

Preferably, the persistence of the virus is determined by immunofluorescence after each clonal purification.

Preferably, the bovine viral diarrhea virus is ncp type bovine viral diarrhea virus, and the virus titer is higher than 10^7.0TCID₅₀。

Preferably, the preservation number of the cell line continuously infected with the bovine viral diarrhea virus is CGMCC No. 22351.

The invention also provides a preparation method of the bovine viral diarrhea virus antibody colloidal gold test strip, which comprises the following steps:

A) carrying out amplification culture on the cell line, harvesting cell culture supernatant and cells, repeatedly freezing and thawing for 2-3 times, and then carrying out differential centrifugation and PEG precipitation to obtain a purified bovine viral diarrhea virus antigen;

B) performing first coupling on the bovine viral diarrhea virus antigen and the colloidal gold to obtain a bovine viral diarrhea virus antigen-colloidal gold coupling marker;

performing second coupling on the IgG and the colloidal gold to obtain an IgG-colloidal gold coupled marker;

C) respectively spraying the bovine viral diarrhea virus antigen-colloidal gold conjugate marker and the IgG-colloidal gold conjugate marker on a glass cellulose membrane, and drying to obtain a gold-labeled binding pad;

respectively scratching bovine viral diarrhea virus antigen and IgG on a detection line and a quality control line on a nitrocellulose membrane;

D) and (3) sequentially sticking the sample pad, the gold-labeled binding pad, the nitrocellulose membrane and the absorption pad on the bottom plate, cutting, assembling and sealing to obtain the colloidal gold test strip for the bovine viral diarrhea virus antibody.

The colloidal gold test strip prepared by the invention can be applied to the monitoring of the immune effect of the bovine viral diarrhea virus and can also be applied to the detection of bovine viral diarrhea virus antibodies in bovine serum in biological product factories.

Preferably, the particle size of the colloidal gold is 40 to 60 nm.

Preferably, in the first coupling, the ratio of the bovine viral diarrhea virus antigen to the colloidal gold solution is 30-40 mug to 1 mL.

Preferably, the ratio of the IgG to the colloidal gold solution in the second coupling is 3.5-4.5. mu.g: 1 mL.

Preferably, the IgG in step B) is mouse IgG and the IgG in step C) is goat anti-mouse IgG.

In the specific embodiment provided by the invention, the bottom plate is a PVC bottom plate.

The invention provides a cell line for stably producing bovine viral diarrhea virus antigen and a preparation method of an antibody colloidal gold test strip. The cell line was prepared as follows: inoculating bovine viral diarrhea virus to sensitive cell line, screening persistent infected cells by limiting dilution method, cloning, purifying, and determining virus titer to be higher than 10^7.0TCID₅₀Establishing a cell line to obtain a cell line continuously infecting the bovine viral diarrhea virus; the sensitive cell line is one of MDBK cell line, BT cell line, PT cell line, ST cell line, PK cell line, CRFK cell line, F81 cell line and MDCK cell line. The invention has the beneficial effects that:

according to the invention, the bovine viral diarrhea virus can continuously infect sensitive cells, and a cell line capable of continuously expressing the bovine viral diarrhea virus antigen is prepared according to the phenomenon. The colloidal gold test strip for detecting the bovine viral diarrhea virus antibody has the characteristics of strong specificity, high sensitivity, simple and quick operation and the like, is easy to popularize, is suitable for detection of basic farms, and has wide market prospect.

The invention combines the enzyme-linked immunosorbent assay principle and the colloidal gold chromatography technology, prepares the colloidal gold test strip for detecting the bovine viral diarrhea virus antibody, is intended to be applied to clinic, improves the prevention capability of the bovine viral diarrhea virus, and has the advantages of simple and quick operation, clear and easily-judged detection result, strong specificity, high sensitivity, no need of instruments and equipment and the like, thereby being very suitable for clinical sample detection in places with limited experimental conditions, such as sites, clinics and the like. The invention provides a preparation method of the test strip, which is suitable for industrial production.

Biological preservation Instructions

And (3) classification and naming: MDBK-BV (bovine kidney cell line stably producing bovine viral diarrhea virus) is preserved in China general microbiological culture Collection center (CGMCC) at 03.06.03.2021, wherein the preservation center is No. 3 of West Lu No. 1 of Beijing Korean district, and the preservation number is CGMCC No.22351 at the institute of microbiology of China academy of sciences.

Drawings

FIG. 1 shows the fluorescence detection results of cell lines producing bovine viral diarrhea virus continuously and stably;

FIG. 2 shows the result of the test strip for detecting the sensitivity of the colloidal gold test strip for bovine viral diarrhea virus antibody.

Detailed Description

The invention discloses a cell line for stably producing bovine viral diarrhea virus antigen and a preparation method of an antibody colloidal gold test strip. It is expressly intended that all such similar substitutes and modifications which would be obvious to one skilled in the art are deemed to be included in the invention. While the methods and applications of this invention have been described in terms of preferred embodiments, it will be apparent to those of ordinary skill in the art that variations and modifications in the methods and applications described herein, as well as other suitable variations and combinations, may be made to implement and use the techniques of this invention without departing from the spirit and scope of the invention.

The invention discloses a cell line capable of stably expressing a bovine viral diarrhea virus antigen and a rapid test strip for preparing a bovine viral diarrhea virus antibody based on the cell line. The specific scheme is as follows:

1. preparing a cell line for continuously and stably producing the bovine viral diarrhea virus antigen: inoculating ncp type bovine viral diarrhea virus to a sensitive cell line, screening continuously infected cells by a limiting dilution method, and carrying out cloning and purification for 3 times, wherein the continuous existence of the virus is determined by immunofluorescence in each cloning and purification. Cloning, purifying, performing amplification culture, and determining to continuously and stably generate the bovine viral diarrhea virus antigen cell line through immunofluorescence and virus titration experiments;

the sensitive cell line refers to cells capable of allowing bovine viral diarrhea virus to replicate, and comprises MDBK cell lines, BT cell lines, PT cell lines, ST cell lines, PK cell lines, CRFK cell lines, F81 cell lines and MDCK cell lines.

2. Virus purification using differential centrifugation and PEG precipitation: carrying out passage and enlarged culture on the obtained sensitive cell line capable of continuously infecting the bovine viral diarrhea virus according to normal cells, harvesting cell culture supernatant and cells, repeatedly freezing and thawing for 3 times, and obtaining a purified bovine viral diarrhea virus antigen through differential centrifugation and PEG precipitation;

3. preparing a conjugate marker of the bovine viral diarrhea virus antigen and the colloidal gold: uniformly mixing 40-60nm colloidal gold placed at normal temperature with a purified bovine viral diarrhea virus antigen, wherein the dosage ratio of the antigen to a colloidal gold solution is 30-40 mug: 1mL, dropwise adding the purified bovine viral diarrhea virus antigen according to the dosage ratio, then adding bovine serum albumin with the final concentration of 1%, stirring to obtain a coupling marker of the bovine viral diarrhea virus antigen and the colloidal gold, and purifying the coupling marker by adopting a low-temperature ultracentrifugation method;

4. preparation of conjugate marker of mouse IgG and colloidal gold: preparing a coupling marker of the mouse IgG and the colloidal gold according to the dosage ratio of 3.5-4.5 mug of the mouse IgG to the colloidal gold solution of 1mL, adding bovine serum albumin with the final concentration of 1%, stirring to obtain the coupling marker of the mouse IgG and the colloidal gold, and purifying the coupling marker by adopting a low-temperature ultracentrifugation method;

5. assembling the test strip: respectively spraying the conjugate marker of the bovine viral diarrhea virus antigen and the colloidal gold and the conjugate marker of the mouse IgG and the colloidal gold on a glass cellulose membrane by using a gold spraying instrument, naturally drying at room temperature, and sealing to obtain a gold-labeled conjugate pad; respectively scratching the purified bovine viral diarrhea virus antigen and goat anti-mouse IgG on a detection line and a quality control line on a nitrocellulose membrane by using a scratching instrument; and (3) sequentially adhering the treated sample pad, the gold-labeled binding pad and the nitrocellulose membrane on a PVC (polyvinyl chloride) base plate, cutting, assembling and sealing to obtain the colloidal gold test strip for the bovine viral diarrhea virus antibody, and storing at room temperature.

The test paper strip comprises a PVC base plate, a sample pad, a gold-labeled combination pad, a nitrocellulose membrane with a detection line and a quality control line and an absorption pad, wherein the materials are sequentially adhered to the PVC base plate, the gold-labeled combination pad is coated with a coupling marker of a purified bovine viral diarrhea virus antigen and colloidal gold and a coupling marker of mouse IgG and colloidal gold, the detection line on the nitrocellulose membrane is coated with the purified bovine viral diarrhea virus antigen, and the quality control line on the nitrocellulose membrane is coated with goat anti-mouse IgG.

The invention is used for cell lines which can continuously and stably produce the bovine viral diarrhea virus antigen and preparing the rapid detection test strip of the bovine viral diarrhea virus antibody based on the cell lines. The method mainly utilizes a non-cytopathic type bovine viral diarrhea virus strain to continuously infect bovine cells, inoculates the non-cytopathic type bovine viral diarrhea virus into sensitive cells, and determines the virus titer to be higher than 10 by cloning, purifying and immunofluorescence technology^7.0TCID₅₀The cell line at/mL is a cell line that stably infects bovine viral diarrhea virus. The virus prepared by the cell line is used as an antigen and is purified to be used in a test strip for quickly detecting BVDV antibody colloidal gold. The test strip has convenient and fast operation, does not need special instruments and equipment, and can be used for detecting the bovine viral diarrhea virus antibody in serum.

The use method of the colloidal gold test strip for detecting the bovine viral diarrhea virus antibody comprises the following steps:

1. and (3) collecting bovine serum, and taking 5 mu L of sample for detection by using a pipette after the serum is naturally separated out.

2. And adding the sucked 5 mu L of sample to the front end of the sample hole of the test strip, then dripping two drops of diluent into the sample hole, displaying the result after 3-10 minutes, and reading the result after 10 minutes.

And (5) judging a result:

1. positive: a red strip appears at each of the detection line and the quality control line, and the detection line and the quality control line are judged to be positive; the color depth of the 5 strips in the detection line changes according to the titer of the bovine viral diarrhea virus antibody in the detection sample, and the color strip is darker when the titer is higher, and is lighter when the titer is higher.

2. Negative: and a red strip appears on the quality control line, and no red strip appears on the detection line, which indicates that no bovine viral diarrhea virus antibody exists in the detection sample.

3. And (4) invalidation: and (3) only a strip is present in the detection line or no obvious strip appears in both the detection line and the quality control line, and the test strip is regarded as invalid.

The reagents or apparatus used in the present invention are commercially available.

The invention is further illustrated by the following examples:

EXAMPLE 1 preparation of a cell line for the sustained Stable production of bovine viral diarrhea Virus antigen

1) Virus inoculation: inoculating a continuous cell line MDBK cell line which is not polluted by exogenous viruses and is sensitive to bovine viral diarrhea viruses into a 6-hole cell culture plate, discarding original culture solution when the cell fusion rate reaches 70%, inoculating the bovine viral diarrhea viruses without cell pathosis with the MOI value of 0.1-0.5, adding a cell culture solution containing 2% of serum after 1h of induction to 37 ℃, and adding 5% CO₂Culturing for 2-3 days.

2) Persistent infectious cell cloning: the above-mentioned inoculated cells cultured in 6-well plates were discarded from the culture medium, washed 1-2 times with PBS, dispersed by trypsinization, diluted with DMEM medium containing 8% serum and passaged to 96-well cell culture plates, observed under a microscope, and wells with only one cell in the well were selected and labeled.

3) Fluorescence identification: after the number of cells in 2) is increased, digesting the marked cells in the well into two parts, adding one part into a 96-well plate for immunofluorescence detection, and carrying out expanded culture on the rest part to a 48-well plate. After the cells in the 96-well plate adhere to the wall, culture solution is discarded, the cells are fixed for 20min by using precooled fixing solution (methanol: acetone ═ 1: 3), the fixing solution is discarded, the cells are washed once by PBS, FITC-labeled anti-BVDV antibody is added, the cells are incubated for 30min at 37 ℃, fluorescent antibody is discarded, the cells are washed three times by PBS and then are observed under a fluorescent microscope. All cells showed specific yellow-green fluorescence.

4) Expansion culture of cloned persistent infected cells: and continuously culturing and subculturing the cells which are subjected to the amplification culture to 48-hole plate, and detecting whether continuous virus infection exists in the cloned cells by applying an immunofluorescence method at the same time of each subculturing.

5) Titer of bovine viral diarrhea virus titer in cloned cells: harvesting the cloned cell strain infected by the virus, freezing and thawing for 3 times, titrating the virus, and measuring the virus content (TCID) by immunofluorescence₅₀) See fig. 1. Finally determining that the virus content is higher than 10^7.0TCID₅₀the/mL cells are cell lines which produce BVDV stably and persistently.

EXAMPLE 2 purification of Virus

Performing amplification culture on a cell line which is applied to continuously and stably produce the bovine viral diarrhea virus antigen, crushing cells to release virus by using an ultrasonic wave or freeze thawing method to obtain the virus antigen, adjusting the pH value of a solution to 7.2-7.5, adding PEG6000 to a final concentration of 8% (w/v), standing overnight at 4 ℃, centrifuging for 2 hours at 10000g, and dissolving a precipitate in PBS to obtain the concentrated and purified virus antigen.

Example 3 preparation of colloidal gold solution

Preparing a colloidal gold solution by adopting a trisodium citrate reduction method: taking 1mL of 1% chloroauric acid solution, adding 99mL of ultrapure water to prepare a chloroauric acid solution with the final concentration of 0.01%, heating to boiling, adding 1mL of 1% trisodium citrate, continuing to heat, changing the solution from light yellow to blue black to wine red, continuing to heat for 5 minutes after the color is stable, cooling at room temperature, and storing at 4 ℃ for later use to obtain a colloidal gold solution. The absorbance of the colloidal gold solution is determined to be 524-536nm by a spectrophotometer, the colloidal gold particles are basically consistent in size and uniform in distribution by transmission electron microscope observation, and the diameter is qualified when the diameter is between 40 and 60 nm.

Example 4 preparation of conjugate marker of bovine viral diarrhea Virus antigen and colloidal gold (gold-labeled bovine viral diarrhea Virus antigen)

Taking a colloidal gold solution with the particle size of 40-60nm and placed at normal temperature, adding 0.1M potassium carbonate solution to adjust the pH value of the colloidal gold solution to 8.2, dropwise adding the purified bovine viral diarrhea virus antigen into the colloidal gold solution under magnetic stirring according to the dosage ratio (30-40 mug: 1mL) of the purified bovine viral diarrhea virus antigen to the colloidal gold solution, continuing stirring for 20 minutes, adding Bovine Serum Albumin (BSA) with the final concentration of 1%, stirring for 15 minutes again to obtain a coupling marker of the bovine viral diarrhea virus antigen and the colloidal gold, namely the gold-labeled bovine viral diarrhea virus antigen, purifying the gold-labeled bovine viral diarrhea virus antigen by adopting a low-temperature ultracentrifugation method to remove the unlabeled bovine viral diarrhea virus antigen in the solution, the colloidal gold which is not fully labeled and various polymers which may be formed in the labeling.

Example 5 preparation of conjugate labels of mouse IgG and colloidal gold

Adjusting the pH value of the colloidal gold solution to 8.2 by using 0.1M potassium carbonate solution, dropwise adding mouse IgG according to the dosage ratio (3.5-4.5 mu g:1mL) of the mouse IgG to the colloidal gold solution under magnetic stirring, continuously stirring for 20 minutes, adding Bovine Serum Albumin (BSA) with the final concentration of 1%, stirring for 15 minutes to obtain a coupling marker of the mouse IgG and the colloidal gold, and purifying the coupling marker of the mouse IgG and the colloidal gold by a low-temperature ultracentrifugation method to remove the unmarked mouse IgG, the incompletely marked colloidal gold and various polymers possibly formed in marking in the solution.

EXAMPLE 6 Assembly of the test strips

(1) Respectively spraying a coupling marker of a bovine viral diarrhea virus antigen and colloidal gold and a coupling marker of mouse IgG and colloidal gold on a glass cellulose membrane by using a gold spraying instrument, wherein the labeling amounts of the coupling marker of the bovine viral diarrhea virus antigen and colloidal gold and the coupling marker of the mouse IgG and colloidal gold are respectively 30-40 mu g:1mL and 3.5-4.5 mu g:1mL, naturally drying and sealing at room temperature to obtain a gold-labeled binding pad 3, and storing at 4 ℃ for later use;

(2) respectively scratching a bovine viral diarrhea virus antigen and a goat anti-mouse IgG on a detection line and a quality control line on a nitrocellulose membrane by using a scratching instrument, wherein the labeling amounts of the bovine viral diarrhea virus antigen and the goat anti-mouse IgG are respectively 2 mug/cm and 4 mug/cm, naturally drying and sealing are carried out at room temperature, so as to obtain the nitrocellulose membrane with the detection line (coated with the purified bovine viral diarrhea virus antigen) and the quality control line 6 (coated with the goat anti-mouse IgG), and storing for later use at 4 ℃;

(3) and (3) sequentially sticking the processed sample pad, the gold-labeled binding pad, the nitrocellulose membrane with the detection line and the quality control line, the absorption pad and the like on a PVC (polyvinyl chloride) bottom plate, cutting, assembling and sealing to obtain the colloidal gold test strip for the bovine viral diarrhea virus antibody, and storing at room temperature for later use.

Example 7 specificity test

The test strip is used for detecting Bovine Viral Diarrhea Virus (BVDV) positive serum, bovine infectious rhinotracheitis virus (IBRV) positive serum, bovine parainfluenza virus III type (BPIV3) positive serum and normal bovine serum.

The results show that: only positive serum of the bovine viral diarrhea virus has an obvious detection line and a control line, and the detection of the rest serum is negative, which shows that the test strip of the invention has good specificity.

Example 8 sensitivity test

The bovine viral diarrhea virus antibody standard substance is diluted by 2 times by using a sample diluent, and then the serum neutralization experiment and the test strip are respectively adopted for detection.

Figure 2 results show that: the highest dilution times detected by a serum neutralization experiment of the same bovine viral diarrhea virus positive serum are 64 times, and the highest dilution times detected by the test strip are 64 times, so that the sensitivity of the test strip is consistent with that of the serum neutralization experiment.

Example 9 compliance testing

100 clinical bovine viral diarrhea virus serum samples stored in the research room are subjected to parallel detection by using the test strip and the serum neutralization experiment respectively, and the results are shown in table 1, wherein the coincidence rate of the test strip relative to the serum neutralization experiment is 97%.

Table 1: test paper strip and coincidence rate detection result of serum neutralization experiment

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.