Expression of nucleoprotein of influenza A virus in Bac-to-Bac TOPO system and evaluation of its immunogenicity
10.13200/j.cnki.cjb.004441
- VernacularTitle:Bac-to-Bac TOPO系统表达甲型流感病毒核蛋白及其免疫原性评价
- Author:
SUN Kewei
- Publication Type:Journal Article
- Keywords:
Bac-to-Bac TOPO system;
Influenza virus;
Nucleoprotein(NP);
Immunogenicity;
Baculovirus;
Insect cells
- From:
Chinese Journal of Biologicals
2025;38(03):257-263
- CountryChina
- Language:Chinese
-
Abstract:
Objective To express nucleoprotein(NP) of influenza A virus in Bac-to-Bac TOPO system and evaluate its immunogenicity,so as to lay a foundation for the research of influenza virus NP protein vaccine.Methods The NP gene of influenza A H1N1(A/Guangdong-Maonan/SWL1536/2019_CNIC-1909) was amplified by PCR and connected to the vector pFastBac~(TM)/CT-TOPO~(TM),which was transformed into competent E.coli One Shot~(TM) Mach1~(TM) T1~R to prepare donor plasmid,and identified by PCR and sequencing.The donor plasmid was transformed into competent E.coli MAX Efficiency~(TM) DH10Bac~(TM),the positive monoclone was screened by blue-white spot screening,and the recombinant bacmid was extracted and identified by PCR.The recombinant bacmid was transfected into Sf9 insect cells to prepare the recombinant baculovirus,and the virus titer was detected by flow cytometry.After multiple rounds of amplification,the recombinant baculovirus infected Sf9 insect cells for the expression of the target protein NP,and the recombinant protein was purified by nickel ion affinity chromatography.Female BALB/c mice were subcutaneously inoculated with recombinant NP protein and PBS respectively,with six mice in each group.The serum specific antibody levels of mice were detected by ELISA,the IFN-γ secreted by spleen cells were detected by flow cytometry,and the CD4~+ and CD8~+ lymphocytes produced by spleen cells were detected by ELISpot.Two weeks after the last immunization,the mice were challenged with A/Guangdong Maonan/SWL 1536/2019_CNIC-1909 influenza virus through nasal cavity,and the body mass changes and survival rate of mice within 14 days after challenge were monitored.Results The results of PCR and sequencing showed that the donor plasmid was constructed correctly.PCR identification results confirmed that the recombinant bacmid was successfully constructed.The titer of recombinant baculovirus was 2.875 × 10~8ivp/mL.The recombinant NP protein showed specific binding to mouse anti-influenza A virus NP monoclonal antibody,with the purity of 91.3% after purification.Two weeks after the last immunization,compared with the PBS group,the serum specific antibody titer(t=0.288,P <0.000 1),the average number of IFNγ spots produced by spleen cells(t=9.235,P <0.000 1),and the number of CD4~+ and CD8~+T lymphocytes produced(t=10.870 and 6.200,P=0.008 4and 0.025 0,respectively) in mice of NA group increased significantly.The mice in PBS group all died within 5 days after infection,while in NP group,one mouse died 5 days after infection,and the other five mice survived.Conclusion The NP protein of influenza A virus expressed by Bac-to-Bac TOPO system has high immunogenicity and can produce strong humoral and cellular immune responses,which can provide certain protection for mice against influenza virus infection.
