CN113354734A

CN113354734A - Kit for rapidly detecting viruses and preparation method thereof

Info

Publication number: CN113354734A
Application number: CN202110793081.5A
Authority: CN
Inventors: 马红妙; 张玲
Original assignee: Beijing Baotu Biotechnology Co ltd
Current assignee: Beijing Xiansheng Xiangrui Biological Products Co.,Ltd.
Priority date: 2021-07-14
Filing date: 2021-07-14
Publication date: 2021-09-07
Anticipated expiration: 2041-07-14
Also published as: CN113354734B

Abstract

The invention discloses a kit for rapidly detecting viruses and a preparation method thereof. The method comprises the steps of screening and obtaining a monoclonal antibody for specifically recognizing respiratory syncytial virus F antigen, preparing a nitrocellulose membrane marked by quantum dots marked by the monoclonal antibody and other antibodies to obtain an antibody fluorescent quantum dot rapid detection test paper, analyzing a gene sequence of respiratory syncytial virus P protein, selecting a conserved region to design an RPA primer and a probe, and preparing the RPA primer and the probe into a corresponding detection test paper; the two detection methods are combined for use, so that the detection accuracy can be further improved, early diagnosis is realized, the patient can be treated as soon as possible, and the method is suitable for large-scale popularization and use.

Description

Kit for rapidly detecting viruses and preparation method thereof

Technical Field

The application relates to the field of biological detection, and more particularly relates to a kit for rapidly detecting viruses and a preparation method thereof.

Background

Respiratory Syncytial Virus (RSV), a mononegavirale RNA Virus of the pneumovirus genus belonging to the family paramyxoviridae, is considered to be the leading pathogen causing acute lower Respiratory infections in infants and young children, and is one of the leading causes of death in infants under the age of 1 year worldwide. The infant patients who need hospitalization due to RSV infection in different regions of the world each year have the disease fatality rate of 1-5% and 1-3%. RSV can be transmitted by a variety of routes, primarily by coughing or sneezing to release droplets containing viral particles or by wiping the eyes or nose after indirect contact with respiratory secretions from infected patients. The main clinical symptoms of people of different ages infected with RSV may be different, after the infants are infected with RSV, symptoms such as high fever, rhinitis, pharyngitis and laryngitis mostly appear, the infants may also be serious lower respiratory diseases such as bronchiolitis and pneumonia, more serious people may develop neurological diseases, and a few patients are accompanied with complications such as otitis media, pleuritis and myocarditis; after infection with RSV in older children and adults, symptoms of upper respiratory infection are predominant. Patients with basic diseases, such as heart and lung diseases (congenital heart disease or lung dysplasia), immunosuppression or deficiency, and the like, are more likely to be severe patients after being infected with RSV.

The genome of the RSV virus has 15191-15226 nucleotides (nt) and encodes 11 proteins. The G, F, SH protein is RSV transmembrane glucoprotein, wherein F and G proteins can mediate adhesion of virus to cells and penetrate membranes and enter cells. The F protein is relatively conserved, the G protein is highly variable, and RSV is mainly divided into two antigen subtypes of RSV-A, RSV-B according to the difference of G protein genes. M, M2-1 and M2-2 are matrix proteins, N, P and L interact to form nucleocapsid, and NS1 and NS2 are non-structural proteins.

Most of RSV infection cases show respiratory tract infection symptoms such as fever, cough, watery nasal discharge and the like, and are confused with other respiratory tract related viruses, so that the judgment of whether a patient is infected by RSV is unreliable in clinical symptoms, and the establishment of an efficient, rapid and accurate detection method is particularly important. Accurate early diagnosis of RSV is not only important for clinical management, but also serves to prevent and control RSV transmission.

At present, RSV (respiratory syncytial virus) detection methods mainly comprise virus isolation culture, immunological detection and etiological detection. The virus culture can be realized only by the existence of live virus, and the operation is complicated and the time consumption is long. The pathogeny detection accuracy is high, the detection time is short, but the equipment is expensive, the detection cost is high, and false positive is easy to appear. The immunological method has short detection time, but low sensitivity, and has unsatisfactory detection effect on low-concentration infection samples. Therefore, the clinical sensitivity of the existing methods is not very desirable.

Content of application

In order to better avoid the defects and provide an early and accurate diagnosis result for a patient, the detection kit is simple to prepare, low in cost, convenient to use, free of a high-precision instrument and more accurate and efficient. The kit detects the respiratory syncytial virus by a nucleic acid-antibody double detection method, can more effectively detect the respiratory syncytial virus and the genotyping thereof (namely whether the respiratory syncytial virus carries the toxin B gene), thereby diagnosing as soon as possible, being beneficial to the treatment of patients as soon as possible and avoiding over-treatment.

The application provides the following technical scheme:

the application provides a monoclonal antibody R17 specifically binding to respiratory syncytial virus F antigen, which comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises a CDR1 region, a CDR2 region and a CDR3 region, and the amino acid sequences of the heavy chain CDR1 region, the CDR2 region and the CDR3 region are respectively shown as

SEQ ID NO

1, 2 and 3; the light chain variable region comprises a CDR1 region, a CDR2 region and a CDR3 region, wherein the amino acid sequences of the light chain CDR1 region, the CDR2 region and the CDR3 region are shown in

SEQ ID NO

4, 5 and 6, respectively.

In another aspect, the present application provides a monoclonal antibody R17 that specifically binds to respiratory syncytial virus F antigen, comprising a heavy chain variable region comprising the amino acid sequence SEQ ID No. 7 and a light chain variable region comprising the amino acid sequence SEQ ID No. 8.

In some embodiments, the monoclonal antibody against respiratory syncytial virus F antigen described herein comprises or consists of two heavy chains and two light chains, wherein each heavy chain comprises a heavy chain constant region sequence, a heavy chain variable region sequence, or a CDR sequence described above, and each light chain comprises a light chain constant region sequence, a light chain variable region sequence, or a CDR sequence described above. The antibody of the present application may be a full-length antibody comprising a constant region, the full-length antibody light chain constant region further comprising murine kappa, lambda chain sequences. The full-length antibody heavy chain constant region further comprises murine IgG1, IgG2a, IgG2b, IgG3, IgA or IgM sequences.

In some embodiments, the monoclonal antibody against respiratory syncytial virus F antigen of the present application is a Fab fragment, Fab 'fragment, F (ab')2 fragment, Fv fragment, diabody, linear antibody, single chain antibody molecule, or multispecific antibody formed from the anti-respiratory syncytial virus antibody or antibody fragment described above.

The application also provides a respiratory syncytial virus fluorescent quantum dot rapid detection test paper, which is prepared by labeling the quantum dots with the R17 monoclonal antibody.

The application provides another test strip RPA (LFD RPA) detection kit for rapidly detecting a respiratory syncytial virus P protein gene, which comprises a lateral flow chromatography test strip, a pair of primers and a probe, wherein the sequence of the upstream primer is shown as SEQ ID NO. 9, the sequence of the downstream primer is shown as SEQ ID NO.10, and the sequence of the probe is shown as SEQ ID NO. 11.

Specifically, the upstream primer (SEQ ID NO: 9):

CAAGATTAGATAGGATTGATGAAAAATTAAG

downstream primer (SEQ ID NO: 10):

Biotin-CACTTTCCTCATTCCTGAGTCTTGCCATAGC

probe sequence (SEQ ID NO: 11):

FAM-GGCAAGTGCAGGACCTACATCTGCTCGGGATGGTATAAGAGATGCCATGAT

in some embodiments, the probes of the present application are modified with a dSpacer at a position 35bp from the middle to the 5' end, thymine (dT) at positions 34bp and 36bp from the 5' end on both sides of the dSpacer molecule are replaced with a fluorophore FAM and a quencher BHQ1, respectively, and modified at the 3' end of the probe with a blocking group C3 Spacer.

In some embodiments, the fluorescent group can be replaced by TAMARA and the quencher group can be replaced by BHQ 2; the dealkalized site can be replaced by tetrahydrofuran; the C3Spacer modification at the 3' end of the probe can be replaced by a phosphate group or other blocking groups.

The test strip is provided with a detection line, and a molecule A is fixed on the detection line;

the primer with the sequence as shown in SEQ ID NO.10 has molecule B capable of combining specifically with the molecule A. The molecule A is a biotin ligand and the molecule B is biotin.

In the test strip RPA detection kit described in the present application, preferably, the kit further includes a hydrolysis buffer solution, magnesium acetate and ddH₂O。

In the test strip method provided by the application, two thymine nucleotides in the middle position of an RPA probe are respectively marked with a fluorescent group and a fluorescence quenching group, an abasic site (dSpacer) is designed between the two thymine nucleotides, and the abasic site can be identified and cut by exonuclease III with 3'-5' exonuclease activity to free the fluorescent group, so that a fluorescent signal is emitted and then is detected by a fluorescence detector; meanwhile, the extensible 3' -OH is left, the DNA polymerase continues to extend and synthesize DNA by taking the probe as a ' forward primer ', and an amplification product with a double label (a fluorescent group label and an affinity label) is amplified together with a reverse primer (with an affinity label, such as biotin); the product is chromatographed on lateral flow test paper, and when encountering a test paper region (usually a line, i.e., "detection line", with streptavidin) that recognizes the affinity label, it is enriched, exhibiting a linear fluorescent signal. The test strip method does not depend on a fluorescent quantitative PCR instrument, so the cost and the application range are wider.

The application further provides a method for detecting the respiratory syncytial virus, which comprises the steps of amplifying a sample by using the primer and the probe, and detecting an amplification product by using a nucleic acid detection test strip. And (4) detecting a result: and (3) combining with a test strip for color development, sucking 5-25 mu L of the amplification product, diluting 10-50 times with a buffer solution of 1xPBST, and detecting with the test strip marked correspondingly. And (4) interpretation of results: the positive (+) of the T line and the C line occurs at the same time, the negative (-) of the C line occurs only, and the effectiveness of the test strip needs to be considered when the T line occurs only.

In some embodiments, the present application provides a nucleic acid-antibody dual detection kit for respiratory syncytial virus, the kit comprising an RPA kit for specifically detecting respiratory syncytial virus nucleic acid and a test strip comprising an anti-RSV F antigen monoclonal antibody for specifically detecting respiratory syncytial virus; the RPA kit contains primers of SEQ ID NO 9 and 10 and a probe of SEQ ID NO 11; the test strip containing the monoclonal antibody is a fluorescent quantum dot rapid detection test strip prepared by labeling quantum dots with an anti-respiratory syncytial virus monoclonal antibody R17; wherein, the anti-respiratory syncytial virus monoclonal antibody R17 comprises a heavy chain variable region comprising the CDR1 shown in SEQ ID NO.1, the CDR2 shown in SEQ ID NO. 2 and the CDR3 shown in SEQ ID NO. 3, and a light chain variable region comprising the CDR1 shown in SEQ ID NO. 4, the CDR2 shown in SEQ ID NO. 5 and the CDR3 shown in SEQ ID NO. 6.

In some embodiments, the present application provides a nucleic acid-antibody dual detection respiratory syncytial virus kit comprising an RPA kit for specifically detecting a respiratory syncytial virus nucleic acid and a test strip comprising an anti-respiratory syncytial virus monoclonal antibody for specifically detecting a respiratory syncytial virus; the RPA kit contains primers of SEQ ID NO 9 and 10 and a probe of SEQ ID NO 11; the test strip of the monoclonal antibody is a fluorescent quantum dot rapid detection test strip prepared by labeling quantum dots with the monoclonal antibody R17 for resisting respiratory syncytial virus; wherein, the heavy chain variable region sequence of the monoclonal antibody of the anti-respiratory syncytial virus R17 is shown as SEQ ID NO. 7, and the light chain variable region sequence is shown as SEQ ID NO. 8.

Use of a kit for the detection of respiratory syncytial virus by determining in vitro the presence and amount of respiratory syncytial virus in a biological sample from a subject.

In some embodiments, the biological sample described herein is a nasopharyngeal secretion, such as a nasopharyngeal swab or a nasal wash sample.

Advantageous effects

The application analyzes the RNA sequence of the respiratory syncytial virus to obtain the specific RPA primer and the specific probe aiming at the respiratory syncytial virus, and prepares a respiratory syncytial virus detection reagent; the test paper is used for diagnosing respiratory syncytial virus patients, can further improve the accuracy of detection, is early diagnosed, is beneficial to the patients to be treated as soon as possible, and is suitable for large-scale popularization and use.

Drawings

The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiment(s) of the application and together with the description serve to explain the application and not limit the application.

FIG. 1 shows the detection of antibody reactivity against respiratory syncytial virus.

FIG. 2 shows the result of subtype identification of anti-respiratory syncytial virus antibody.

Figure 3 shows an anti-respiratory syncytial virus antibody neutralization assay.

FIG. 4 shows the result of the sensitivity of the RPA reaction of respiratory syncytial virus. Wherein FIG. 4A shows the results of sensitive detection of the RPA response of RSV type A antigen; FIG. 4B shows the results of the sensitivity of the RPA response to RSV type B antigen.

Detailed Description

The preferred embodiments of the present application will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein only to illustrate and explain the present application and not to limit the present application.

Example 1 preparation of recombinant RSV F antigen and RSV infected cells

Preparation of recombinant RSV F antigen: the RSV F antigen extracellular domain (synthesized by Shanghai Czeri bioengineering, Inc.) was cloned into the eukaryotic expression vector pcDNA3.1 by subcloning, and a 6X-His tag or other tags commonly used by those skilled in the art were added to the F antigen. A leader sequence corresponding to the human vkappa I signal peptide was introduced at the amino terminus to facilitate secretion. Constructing expression vector pcDNA3.1-F ECD. Recombinant RSV F protein extracellular domain was expressed and purified according to the manufacturer's instructions. Briefly, expression vectors were transfected into 293F cells for expression. Culture supernatants were collected after 72h and protein purified. A5 mL size Ni column (pre-packed column) was attached to the purifier path and the column was equilibrated with a 30mL volume Binding buffer at a flow rate of 1mL/min while the collection tray collection volume was set to 2 mL/tube. And (3) loading 5mL of culture solution supernatant from an instrument loading hole at the flow rate of 0.5mL/min, after the sample flows through the column, respectively Washing and eluting by using 30mL of Washing buffer and Elution buffer, collecting eluent, desalting and concentrating through an ultrafiltration tube, measuring the concentration, and subpackaging and storing at-80 ℃ for later use.

Preparation of RSV-infected cells: studies have shown that RSV infected cells have a large amount of F protein on their surface, and thus RSV infected cells are prepared as antigens. HEp-2 cells were infected with RSV, cultured for 48h, and then harvested using a cell scraper, and the MEM medium was removed by centrifugation. The cell pellet was resuspended with 500. mu.L of 1XPBS and ready for preparation.

Example 2 in situ ELISA detection

Culturing Hep2 cells, and when the cells grow to be full of 90% culture dishes, replacing the culture medium, and reserving 2mL of culture medium for each 10cm culture dish; taking out virus strain from-80 deg.C, rapidly melting in 37 deg.C water bath, adding 200 μ L virus into each dish, and shaking cell culture dish to make virus and cell fully contact; placing on a cell shaking table for incubation for 1 h; add 10Ml MEM complete medium, 5% CO per dish of cells₂And culturing at 37 ℃ for 24 h. Infected Hep2 cells were digested with pancreatin and harvested by centrifugation. After resuspending and blowing the cells into single cells, counting and adjusting the cell concentration to 5X10⁵one/mL, which was added to a 96-well plate at 100 μ L per well. 5% CO₂Culturing at 37 deg.C for 24 hr until the cells are completely attached to the wall; discard the culture medium, add 50 μ L of the fixative to each well, and fix for 10min in dark. Discarding the fixative, and adding 200 μ L PBS per well for washing; add 180. mu.L of blocking solution to each well and block for 2h at 37 ℃. Discarding the confining liquid, after patting dry, adding the antibody to be detected and the corresponding secondary antibody for incubation, then adding the developing solution and the stop solution to complete the developing process, reading the plate by using an enzyme-linked immunosorbent assay, processing the experimental data and drawing the image.

Example 3 preparation of anti-respiratory syncytial virus F antigen antibodies

Immunization with recombinant RSV F protein purified in example 1 as antigenBALB/c female mice. The recombinant protein is mixed with the Freund's adjuvant with the same volume (1 mL: 1mL), and is fully emulsified by a syringe method, and a mouse is immunized by tail vein injection, wherein the immunization dose is 100 mu g/mouse, and the immunization lasts for 3 weeks. After 3 weeks, RSV-infected cells prepared in example 1 were taken and boosted. That is, 50. mu.L of RSV-infected cell suspension prepared in example 1 was immunized into the spleen. After 3 days, spleens of immunized BALB/c mice were ground and splenocytes were isolated, fused with myeloma Sp2/0 cell line by the PEG method, and the fused cells were resuspended in 20% 1640HT medium, 1% aminopterin was added, and then spread uniformly in 96-well plates at 37 ℃ and 5% CO₂And (5) culturing. After half of the fused cells were cultured for about one week, the culture supernatant was collected 3 days after the half of the culture, and the positive clones were detected by the in situ ELISA method described in example 2. And (4) carrying out cloning culture on the screened positive clones by adopting a limiting dilution method. And (3) screening by using an in-situ ELISA method to finally obtain a positive hybridoma cell strain which is named as R17. After expansion culture, the hybridoma cells were cryopreserved.

EXAMPLE 4 purification of monoclonal antibodies

BALB/c mice were injected intraperitoneally with 0.5 ml/mouse, 1 week before hybridoma inoculation. After 1 week, each mouse was inoculated intraperitoneally at about 1X10⁶(ii) individual hybridoma cells; and after 7-10 days, collecting ascites. Centrifuging ascites at 10000 Xg for 30min, removing precipitate, salting out with 50% ammonium sulfate, coarse extracting, dissolving with PBS, and dialyzing with flowing water for 5 hr; dialyzing and equilibrating with 0.1mol/L phosphate buffer (pH8.0) overnight; and (3) loading, eluting the hybrid protein by using 0.1mol/L phosphate buffer solution (pH8.0), eluting by using citrate eluents with different pH values, collecting elution peaks in sections, and concentrating to obtain the purified anti-respiratory syncytial virus antibody R17.

Example 5 detection of antibody reactivity against respiratory syncytial Virus

The binding activity of the monoclonal antibody against RSV F protein to F protein on the cell surface was preliminarily measured by an in situ ELISA method using Hep2 after RSV infection as an antigen and treated with a fixative. anti-RSV monoclonal antibodies at an initial concentration of 10. mu.g/mL were expressed as 1: 10 fold proportional dilutions, 6 gradients were diluted. The results are shown in figure 1, where the R17 antibody binds RSV F protein in a dose-dependent manner.

Example 6 anti-respiratory syncytial virus antibody subtype identification

The positive mouse monoclonal cell line selected by indirect ELISA was subjected to subclass measurement using a subclass measuring reagent (Sigma). The elisa plates provided in the kit had been pre-coated with specific antibodies against mouse IgG1, IgG2a, IgG2b, IgG3, IgA, IgM, kappa light chain, lambda light chain, and the anti-respiratory syncytial virus antibody R17 sample purified in example 4 was added to the sample wells at 50 μ L per well without incubation. Adding 1X goat anti-mouse IgA + IgM + IgG-HRP into sample wells, mixing the sample wells with 50 mu L each, and incubating for 1 h. And (4) deducting liquid in the holes, adding 1XPBST to wash the holes for 3 times, and absorbing the excessive moisture by absorbent paper. Adding color development solution, each well is 100 μ L, and developing at room temperature in dark for 15 min. 100. mu.L of stop solution was added to terminate the color reaction. As shown in FIG. 2, the monoclonal antibody of the present invention is an IgG1 subtype.

Example 7 sequence determination of monoclonal antibodies

Taking out the R17 hybridoma cell freezing tube from liquid nitrogen, quickly thawing at 37 ℃, centrifuging at 1000rpm for 5min to remove the freezing solution, placing the tube in a 100mm pore plate, culturing until the tube accounts for about 80% of the culture plate, adding 1ml of Trizol reagent (Thermo company), and extracting the total RNA of the hybridoma cells according to the instruction. Mu.g of the above total RNA was taken, DECP water was added thereto to make the volume to 11. mu.L, 1.0. mu.L of oligo (dT) (10. mu.M) was added thereto, 1. mu.L of dNTPs (10mM) was added thereto, the mixture was mixed well, incubated at 65 ℃ for 5 minutes and then placed on ice for 1 minute, followed by addition of 4. mu.L of RT buffer (5X), 1.0. mu.L of DTT (100mM), 1. mu.L of Ribonucleae Inhibitor and 1. mu.L of reverse transcriptase (takara Co., Ltd.), and reacted at 50 ℃ for 10 minutes. The reaction was terminated by incubation at 80 ℃ for 10 minutes, and the obtained cDNA was stored at-20 ℃. Designing specific nested PCR primer, the primer sequence used in the amplification reaction is complementary with the first frame region and the constant region of the antibody variable region, and amplifying the target gene by adopting a conventional PCR method. The primer sequences were designed according to the literature (Bodo Brocks. Specifes-Cross active scFv Against the turbine Stroma Marker "fibrous Activation Protein" Selected by phase Display From an amplified FAP)^-/-Knock-Out Mouse).

Sequencing results show that the amino acid sequences of the heavy chain and light chain variable regions of the anti-respiratory syncytial virus antibody R17 are respectively shown as SEQ ID NO:7 and SEQ ID NO:8 is shown in the specification; the amino acid sequences of 3 CDRs in the heavy chain variable region of the antibody are respectively shown as SEQ ID NO 1, SEQ ID NO 2 and SEQ ID NO 3; the amino acid sequences of 3 CDRs in the light chain variable region are shown in SEQ ID NO. 4, SEQ ID NO. 5 and SEQ ID NO. 6, respectively.

Example 8 neutralization assay of anti-RSV antibodies

Will have a density of 5x10⁵Hep2 cells were added at 100. mu.L/well to 96-well plates per mL. 5% CO₂And cultured at 37 ℃. An anti-RSV monoclonal antibody at a concentration of 100 μ g/mL was administered at a rate of 1: 10 and mixed with an equal volume of RSV a-type virus or RSV B-type virus (MOI 2) and incubated for 1h at 37 ℃. After 1 hour, 100. mu.L of a mixture of the virus and the anti-RSV F protein antibody was added to a 96-well plate containing cells, and incubated at 37 ℃ for 24 hours. After 24h, the fluorescence intensity was read using a multifunctional microplate reader. Data were analyzed using GraphPad software and neutralization titers of samples were calculated, expressed as IC50 values. As a result, as shown in fig. 3, the anti-RSV F protein antibody R17 can neutralize both RSV a-type virus and RSV B-type virus, and is a broad-spectrum antibody; wherein the antibody R17 neutralizes RSV type A virus with an IC50 value of about 0.02512 μ g/mL and RSV type B virus with an IC50 value of about 0.05629 μ g/mL.

Example 9 preparation of polyclonal antibodies against respiratory syncytial Virus

Female rabbits were immunized with the purified recombinant RSV F protein of example 1 as antigen. The recombinant protein is mixed with Freund's adjuvant with the same volume (1 mL: 1mL), and the mixture is fully emulsified by a syringe method, and the rabbit is immunized by tail vein and back multipoint injection, and the immunization dose is 500 mu g/rabbit. Then mixing Freund's incomplete adjuvant and recombinant F antigen in equal volume, and immunizing with tail vein and back multipoint injection method at an immunizing dose of 500 μ g/mouse for 3 weeks. After 3 weeks, RSV-infected cells prepared in example 1 were taken and boosted. That is, 200. mu.L of RSV-infected cell suspension prepared in example 1 was immunized into the spleen. Blood is collected from the heart one week after the last immunization, the collected serum is firstly stood for 2 hours at room temperature, then is transferred to 4 ℃ for standing overnight, is centrifuged for 15min at 4000rpm, and the collected supernatant is respectively packed in a 5mL centrifuge tube and is reserved at-80 ℃ for later use. And taking part of serum to carry out serum titer detection. The residual serum was removed from-80 ℃ and thawed at room temperature, and 0.5m L serum was diluted to 10mL with 1:20 balance, filtered through a 0.45 μ L filter and placed in a new centrifuge tube. The Protein A pre-packed column was connected to the purifier path, and 10mL of the equilibration solution was taken to equilibrate the column at a flow rate of 1 mL/min. The treated serum was sampled at a flow rate of 0.5 mL/min. Click open the collection tray at the same time, set the collection volume to 1.5 mL/tube. The mixture was washed and eluted with 10mL of the equilibration and elution solutions, and 300. mu.L/tube of the neutralization solution was added to the collection tray, so as to prevent the purified antibody from being denatured and degraded in the acidic elution solution. After purification, collecting the eluates, ultrafiltering, desalting and concentrating by ultrafiltration tube to obtain polyclonal antibody against respiratory syncytial virus F protein, detecting antibody concentration, and subpackaging at-80 deg.C for use.

EXAMPLE 10 preparation of test paper for rapid detection of respiratory syncytial virus fluorescent quantum dots

Taking 1mL of carboxyl modified fluorescent quantum dots, centrifuging at 18000rpm for 20min, re-suspending the precipitate with 0.1mol/L MES solution, centrifuging for 2 times, adding 5mmol/L EDC and 2mmol/L NHS for activation reaction for 30min, adding 0.5mg of the anti-RSV F protein monoclonal antibody R17 purified in the example 4 after activation, reacting for 3h in a constant temperature box at 37 ℃, adding 5% BSA (bovine serum albumin), sealing the rest of the activation sites and reacting for 30 min; the labeled antibody was purified by centrifugation and resuspended in 1% BSA in PBS and stored at 4 ℃. Goat anti-mouse IgG was prepared to 0.5mg/mL in PBS buffer, and the anti-RSV F protein polyclonal antibody purified in example 9 was prepared to 1mg/mL in PBS buffer and coated with nitrocellulose. Spraying goat anti-mouse IgG on the position of a quality control line (C line), spraying the coating antibody on the position of a detection line (T line), and drying at 37 ℃ for 4 h. And (3) assembling the dried nitrocellulose membrane with a glass fiber mat, absorbent paper and a PVC (polyvinyl chloride) back plate, and cutting to obtain the RSV rapid detection test paper for detection. During detection, the quantum dot labeled anti-RSV F protein antibody is diluted by 1: 100 times, 20uL and 40uL samples are mixed and then dripped to the sample adding end of the RSV rapid detection test paper, and the reaction is carried out for 15min and then the detection is carried out by a fluorescence immunochromatography detector. If fluorescence bands appear on both the T line and the C line, judging the line to be positive; if the C line has a fluorescent strip and the T line has no strip, judging the result as negative; if the line C has no strip, whether the line T has a strip or not is judged that the test strip is invalid.

Example 11 evaluation of specificity of respiratory syncytial virus fluorescent Quantum dot test strip

Negative reference adenovirus (HAdV), influenza a virus (IFVA), influenza B virus (IFVB), parainfluenza virus 1(PIV1), parainfluenza virus 2(PIV2), parainfluenza virus 3(PIV3), and positive reference RSV a and RSV B of different subtypes were detected using the test strips prepared in example 10, respectively. The specificity of the test strip was analyzed by observation.

The detection results are shown in table 1, and the results show that the results of the rapid detection test paper for the respiratory syncytial virus fluorescent quantum dots, HAdV, IFVA, IFVB, PIV1, PIV2 and PIV3 are negative, and the results of the rapid detection test paper for the respiratory syncytial virus fluorescent quantum dots and RSV A and RSV B are positive, so that the test paper prepared by the application has good specificity, can be used for simultaneously detecting the respiratory syncytial virus A and B, and has good broad spectrum.

TABLE 1

Sample name	T line	C line
			HAdV	-	+
IFVA	-	+
			IFVB	-	+
PIV1	-	+
			PIV2	-	+
PIV3	-	+
			RSV type A	+	+
RSV type B	+	+

Example 12 design of RPA-specific detection primers

And comparing the gene sequences of the respiratory syncytial viruses of various subtypes, and finally selecting the P gene with higher conservation type as a target gene amplification region. Manually designing primers in a P gene region according to an RPA primer design principle, carrying out preliminary evaluation by means of related biological software such as Oligo and the like, screening the primers by using an RPA gel reaction system, and finally determining the primers with high amplification efficiency and good specificity as the selected primers. In the designed primer amplified fragment sequence, an RPA probe is manually designed according to the RPA probe design principle, and is evaluated by using related molecular biology software such as Oligo, and the synthesis and HPLC purification of the primer and the probe are finished by the company of Biotechnology engineering (Shanghai).

The sequences of the RPA primer and the probe set for detecting the respiratory syncytial virus P gene are as follows:

upstream primer (SEQ ID NO: 9):

CAAGATTAGATAGGATTGATGAAAAATTAAG

downstream primer (SEQ ID NO: 10):

Biotin-CACTTTCCTCATTCCTGAGTCTTGCCATAGC

probe sequence (SEQ ID NO: 11):

FAM-GGCAAGTGCAGGACCTACATCTGCTCGGGATGGTATAAGAGATGCCATGAT

dSpacer modification is adopted at a position 35bp away from the 5' end in the probe, thymine (dT) at positions 34bp and 36bp away from the 5' end on both sides of dSpacer molecules are respectively replaced by a fluorescent group FAM and a quenching group BHQ1, and the 3' end of the probe is modified by a blocking group C3 Spacer.

Example 13 respiratory syncytial Virus RNA extraction

Viral RNA extraction of clinical specimens was performed using a viral RNA extraction kit (Tiangen), and the whole nucleic acid extraction process was performed strictly according to the kit instructions by adding 560. mu.L of Carrier RNA working solution (which is a mixture of lysate RV + and Carrier RNA solution) to a clean 1.5ml centrifuge tube using a pipette. Add 140. mu.L of plasma/serum/lymph/cell-free body fluid/cell culture supernatant/urine to the centrifuge tube (the sample needs to be equilibrated to room temperature), vortex and mix well for 15s, incubate for 10min at room temperature. Adding 560. mu.L of absolute ethanol, covering the tube cap and vortexing for 15s, performing instantaneous centrifugation, carefully transferring 630. mu.L of the liquid in the centrifuge tube to RNase-Free adsorption column CR2 (the adsorption column is placed in a 2mL collection tube), covering the tube cap, centrifuging at 8000rpm for 1min, discarding the collection tube containing the waste liquid, placing the adsorption column in a new 2mL collection tube, and repeating for 2 times. The adsorption column cover was opened, 500. mu.L GD buffer was added, centrifugation was carried out at 8000rpm for 1min, the collection tube containing the waste liquid was discarded, and the adsorption column was placed in a new collection tube of 2 mL. Adding 500 μ LRW rinsing solution, centrifuging at 8000rpm for 1min, and discarding the collecting tube containing waste liquid. The adsorption column was placed in a new 2mL collection tube and centrifuged at 12000rpm for 3 min. Placing the adsorption column into an RNase-Free ultra-clean centrifugeTo a tube (1.5mL), 60. mu.L of RNase-Free ddH was added to the center of the membrane₂O, covering the cover, and standing at room temperature for 5 min. Centrifuge at 8000rpm for 1 min.

Example 14 detection of sensitivity of RPA reaction

Preparing RSV A and RSV B positive plasmid standard substance as template, and ten-fold gradient dilution to make final concentration after dilution be 10 respectively⁴-10⁰The RPA reaction was carried out using the primer and probe set selected in example 12, with no ribozyme water as a negative control.

The RPA reaction system is 50 mu L, wherein, 2 mu L of forward and reverse primers (10 mu M), 2 mu L of reverse primers (10 mu M), 0.6 mu L of probe, 25 mu L of buffer solution containing recombinase, reverse transcriptase, DNA polymerase, single-strand binding protein and endonuclease IV, 1 mu L of template and 17.9 mu L of ddH2O are fully shaken, mixed evenly and separated instantly, finally 2.5 mu L of 280mM magnesium acetate is added, and the reaction tube is placed in a real-time fluorescence PCR instrument for 30min at the constant temperature of 38 ℃; as a result, as shown in FIGS. 4A-4B, RSV A and RSV B showed the lowest detection of 10 copies of the recombinant plasmid containing the desired gene per reaction, respectively, by the real-time fluorescent RT-RPA method.

Embodiment 15 preparation of test strip for detecting respiratory syncytial virus RPA and specificity detection

Streptavidin-coated gold nanoparticles were prepared by adding 200mM borax solution to 1mL gold nanoparticle solution (0.15pmol/mL) and adjusting the pH to 9.5. At the same time, 2. mu.L of streptavidin (2mg/ml) was mixed with 398. mu.L of borax solution (2mM) in another tube; the diluted streptavidin was added to the aforementioned gold nanoparticle solution in an amount of 50. mu.L, and the solution was stirred while adding. The mixture was left at room temperature for 45 minutes, 155.6. mu.L of a 2mM borax solution containing 10% BSA was added, the solution was left at room temperature for another 10 minutes, 4500g was centrifuged for 15 minutes, the liquid was aspirated, the precipitate was resuspended in 1ml of a wash solution (2mM borax solution containing 10g/L BSA), 4500g was centrifuged for 15 minutes, the liquid was aspirated, and the red precipitate was resuspended in 250. mu.L of a buffer containing 5% BSA, 137mM NaCl and 0.025% Tween-200. A sufficient amount of streptavidin-coated gold nanoparticles was prepared in this ratio, 250. mu.L of the coated gold nanoparticles were dropped onto a 7mm by 300mm laser-cut glass fiber pad, allowed to spread uniformly, and dried overnight on a laboratory bench.

The test strip for colloidal gold lateral flow immunochromatography was prepared by diluting an anti-carboxyfluorescein antibody and biotinylated anti-mouse IgG to final concentrations of 0.5mg/ml and 1.0mg/ml, respectively, with 100mM sodium bicarbonate buffer containing 5% methanol, 2% sucrose. All antibodies were dispensed using a lateral flow reagent dispenser with a dispenser head speed set at 1-3 cm/min, preferably 2 cm/min, and a syringe pump flow rate set at 0.1-0.3 ml/min, preferably 0.1 ml/min. After completion of the spotting of both antibodies on the strip, the strip was dried at 37 ℃ for 1 hour. The test card was then assembled by first placing a 17mm x 300mm absorbent pad on the right hand downstream end of a plastic-supported nitrocellulose membrane, the two being superposed by 2 mm; a 7mm x 300mm glass fibre mat containing dried gold nanoparticles was then placed on the left hand upstream end of the nitrocellulose membrane, overlapping by 2 mm; finally, a 12mm by 300mm glass fiber sample pad was placed on the left hand end of the gold nanoparticle pad, with the two overlapping by 2 mm. After the assembly is completed, the test paper card is immediately cut into test paper strips with the width of 3mm, and the colloidal gold lateral flow immunochromatographic test paper strips are obtained, sealed, dried and stored.

In addition, the RPA kit for respiratory syncytial virus comprises the primers and probes designed in example 12, a hydrolysis buffer, an enzyme mixture, magnesium acetate (280mM), nuclease-free pure water, and a lateral chromatography strip with a detection line on which molecular streptavidin is immobilized, which is capable of specifically binding to biotin at the terminal end of primer SEQ ID NO: 10.

The test strip is used for detecting HAdV, IFVA, IFVB, PIV1, PIV2 and PIV3 genomes respectively so as to determine the specificity of the RPA detection method. The RPA reaction system was 50. mu.L, with 2. mu.L forward and reverse primers (10. mu.M), 2. mu.L reverse primer (10. mu.M), 0.6. mu.L probe, 25. mu.L containing recombinase, reverse transcriptase, DNA polymerase, single-stranded binding protein, endonuclease IV, 1. mu.L sample and 17.9. mu.L ddH2O, mixed well with shaking and flash-detached, and finally 2.5. mu.L of 280mM magnesium acetate was added. The reaction was carried out in a water bath at 38 ℃ for 30 min. The result shows that the respiratory syncytial virus RSV A and RSV B samples simultaneously show a T line and a C line, and the samples of other pathogens only show a C line, so that the RPA test strip kit can effectively detect the respiratory syncytial virus, and the results are shown in the following table 2.

TABLE 2

Sample (I)	LFD RPA T line	LFD RPA C line
			HAdV	-	+
IFVA	-	+
			IFVB	-	+
PIV1	-	+
			PIV2	-	+
PIV3	-	+
			RSV type A	+	+
RSV type B	+	+

EXAMPLE 16 actual sample testing

310 samples of nasopharyngeal secretion of children with RSV A and RSV B are taken, and 100 negative control samples are taken, wherein the samples are from Shandong university's Qilu hospital.

The samples are respectively detected by adopting fluorescent quantum dot rapid detection test paper and test paper strip RPA, and the detection results are shown in Table 3. The results in table 3 show that the antibody fluorescent quantum dot test strip and the RPA test strip can be used for detecting A, B positive respiratory syncytial virus patients well, the positive rate of the fluorescent quantum dot rapid detection test strip is 91.9%, the positive rate of the test strip RPA test strip is 93.8%, the positive rate of the fluorescent quantum dot rapid detection test strip and the test strip RPA combined detection respiratory syncytial virus reaches 100%, and the combined detection of the fluorescent quantum dot rapid detection test strip and the test strip RPA is higher than that of the single detection of the fluorescent quantum dot rapid detection test strip and the test strip RPA. Therefore, the combined application of the fluorescent quantum dot rapid detection test paper detection and the test paper RPA further improves the diagnosis accuracy. The combination of the detection of the respiratory syncytial virus F antigen and the detection of the protein P gene can achieve good supplementation and enhance the accuracy of the detection result.

TABLE 3

Sequence listing

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Claims

1. A monoclonal antibody specifically binding to respiratory syncytial virus, characterized in that the heavy chain variable region of the monoclonal antibody comprises CDR1 shown in SEQ ID NO.1, CDR2 shown in SEQ ID NO. 2 and CDR3 shown in SEQ ID NO. 3, and the light chain variable region thereof comprises CDR1 shown in SEQ ID NO. 4, CDR2 shown in SEQ ID NO. 5 and CDR3 shown in SEQ ID NO. 6.

2. An antibody specifically binding to a respiratory syncytial virus monoclonal antibody is characterized in that the heavy chain variable region sequence of the monoclonal antibody is shown as SEQ ID NO. 7, and the light chain variable region sequence thereof is shown as SEQ ID NO. 8.

3. A kit for detecting respiratory syncytial virus, which is characterized by comprising a fluorescent quantum dot rapid detection test strip prepared from the monoclonal antibody labeled quantum dot of claim 1 or 2.

4. A kit for detecting respiratory syncytial virus by nucleic acid-antibody dual detection comprises the kit of claim 3 and a test strip RPA detection kit, wherein the test strip RPA detection kit comprises a pair of primers and a probe, the sequences of the pair of primers are shown as SEQ ID NO. 9 and 10, and the sequence of the probe is shown as SEQ ID NO. 11.

5. The kit of claim 4, wherein the probe is labeled with a fluorophore, a fluorescence quencher, an abasic site, and a blocking group.

6. The kit according to claim 5, wherein the fluorescent group is FAM, the fluorescence quenching group is BHQ1, the abasic site is dSpacer modification and the blocking group is C3Spacer modification.

7. The kit according to claim 5, wherein the fluorescent group is TAMARA, the fluorescence quenching group is BHQ2, the abasic site is modified with tetrahydrofuran, and the blocking group is modified with C3 Spacer.

8. A kit as claimed in any one of claims 4 to 7, wherein the kit further comprises a hydrolysis buffer, magnesium acetate and ddH₂O。

9. The kit according to claim 8, wherein the RPA amplification reaction is carried out in a water bath set at 38 ℃ for 30 min.