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CN-121991207-A - Antibody or antigen binding fragment thereof for Nsp7 protein of porcine reproductive and respiratory syndrome virus and application thereof

CN121991207ACN 121991207 ACN121991207 ACN 121991207ACN-121991207-A

Abstract

The application discloses an antibody or antigen binding fragment thereof for Nsp7 protein of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), which comprises a heavy chain and a light chain, is capable of specifically recognizing the Nsp7 protein and is used for detection thereof. Since Nsp7 is only expressed at the time of viral infection and vaccine immunization does not induce antibody production, infection and immune Differentiation (DIVA) can be achieved by detecting anti-Nsp 7 antibodies. Meanwhile, NSp7 is highly conserved among different PRRSV strains, so that the broad spectrum and stability of detection can be improved, and the method is suitable for the application of infection monitoring and immune identification of PRRSV.

Inventors

  • SHAO MIN
  • ZHOU HEFENG
  • YANG CHANGYAN

Assignees

  • 遵义医科大学珠海校区

Dates

Publication Date
20260508
Application Date
20260129

Claims (10)

  1. 1. An antibody for Nsp7 protein of porcine reproductive and respiratory syndrome virus is characterized in that the amino acid sequence of a heavy chain variable region of the antibody is shown as SEQ ID NO. 1, and the amino acid sequence of a light chain variable region of the antibody is shown as SEQ ID NO. 2.
  2. 2. The antibody of claim 1, wherein the antibody type is IgG1 and the light chain is a kappa light chain.
  3. 3. An antigen binding fragment that specifically binds to the antibody of claim 1 or 2.
  4. 4. A nucleic acid molecule encoding the antibody of claim 1 or 2, wherein said nucleic acid molecule comprises a nucleotide sequence encoding a heavy chain variable region as set forth in SEQ ID No. 3 and a nucleotide sequence encoding a light chain variable region as set forth in SEQ ID No. 4.
  5. 5. A recombinant expression vector comprising the nucleic acid molecule of claim 4.
  6. 6. The recombinant expression vector of claim 5, wherein the vector is a pGEX-4T-1 expression vector.
  7. 7. A host cell comprising the recombinant expression vector of claim 5 or 6.
  8. 8. A GST-Nsp7 fusion protein obtained from the recombinant expression vector of claim 5 or 6 after induced expression in the host cell of claim 7.
  9. 9. The use of the fusion protein according to claim 8 for immunization against Nsp7 protein antibodies of porcine reproductive and respiratory syndrome virus.
  10. 10. Use of an antibody or antigen-binding fragment thereof according to any one of claims 1-3 in the preparation of a reagent or kit for detecting Nsp7 protein of porcine reproductive and respiratory syndrome virus.

Description

Antibody or antigen binding fragment thereof for Nsp7 protein of porcine reproductive and respiratory syndrome virus and application thereof Technical Field The invention relates to the technical field of antibodies, in particular to an antibody or an antigen binding fragment thereof aiming at porcine reproductive and respiratory syndrome virus Nsp7 protein and application thereof. Background Porcine reproductive and respiratory syndrome (Porcine Reproductiveand Respiratory Syndrome, PRRS), commonly known as porcine reproductive and respiratory syndrome, is a highly contagious disease caused by PRRS virus (PRRSV). The virus can infect pigs of all ages through various ways such as contact, air transmission and the like, has obvious harm to pregnant sows and piglets, has clinical manifestations mainly including sow reproductive disorders (such as abortion, stillbirth, mummy, weaning and the like) and piglet respiratory symptoms, and can cause obvious increase of piglet mortality. PRRSV has obvious immunosuppressive properties, can target to destroy alveolar macrophages, causes the body resistance to be reduced, is easy to be infected by secondary bacteria or viruses, forms malignant circulation of 'immunosuppression-multiple infection', causes great economic loss to the global pig industry, and severely restricts the sustainable development of intensive culture. At present, prevention and control of PRRS mainly depend on comprehensive measures taking vaccine immunity and monitoring purification as cores, wherein an accurate and rapid diagnosis technology is a key for realizing effective monitoring and epidemic situation tracing. Existing diagnostic methods for Porcine Reproductive and Respiratory Syndrome (PRRS) are diverse, but each has limitations. The method has the advantages that the method is definite in result, but complicated in process, long in time consumption and difficult to meet the requirement of rapid screening of a basic layer, the technology such as RT-PCR, real-time fluorescence quantitative PCR, loop-mediated isothermal amplification (LAMP) and the like has high sensitivity and specificity in the aspect of molecular biological detection, but depends on precise instruments and professional operation, and is not suitable for field application of pig farms, and in serological detection, an indirect immunofluorescence test and a virus neutralization test have specificity, but are low in flux and strong in subjectivity, or early diagnosis cannot be realized due to lag of neutralizing antibodies (1-2 months after infection). In contrast, enzyme-linked immunosorbent assay (ELISA) becomes the mainstream technology of PRRSV serological detection by virtue of the advantages of high throughput, low cost, simple operation and the like, but the current ELISA kit still faces the problems of single target point, difficulty in distinguishing wild virus infection from vaccine immunity, dependence of part of core reagents on import and the like, and the accurate application of the ELISA kit in a basic layer is restricted. Therefore, developing PRRSV monoclonal antibodies with independent intellectual property rights not only can provide core raw materials for establishing high-sensitivity and high-specificity sandwich ELISA, blocking ELISA and other detection methods, but also can break through the bottleneck of the prior art in the aspects of distinguishing wild viruses from vaccine strains and covering polygenic strains, and provides key support for developing domestic and accurate PRRSV on-site rapid detection technologies. PRRSV belongs to the genus arterivirus of the family arterividae, is a single-stranded positive strand RNA virus, has a genome length of about 15kb, and is largely divided into two genotypes, PRRSV-1 (European type) and PRRSV-2 (American type). The current epidemic strain in China is mainly PRRSV-2, wherein NADC30-like strain of pedigree 1 becomes dominant epidemic strain. The Nsp7 protein is encoded by ORF1b and has a molecular weight of about 28.65kDa, which is a key component in the PRRSV nonstructural protein family, and is involved in the formation of viral RNA polymerase complex, playing a central role in the viral genome replication process. Unlike GP5, N, etc., structural proteins, nsp7 is expressed in cells only after virus infection of host cells, but none of the existing commercial PRRS vaccines (including inactivated and attenuated vaccines) contain the complete ORF1b encoding region, and cannot induce the body to produce specific antibodies against Nsp 7. Therefore, the Nsp7 can be used as an ideal target for infection and immune Discrimination (DIVA), wherein naturally infected pigs produce anti-Nsp 7 antibodies and antibodies aiming at structural proteins, vaccine immunized pigs only produce antibodies aiming at the structural proteins, and accurate discrimination between the anti-Nsp 7 antibodies can be realized by detecting the anti-Nsp 7 antibodies, so that the techni