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【Objective】 To construct the secretory expression system of insect cells to express the secretory TSHR A subunit protein in the ovarian cells of Spotoma oryzae (sf9). 【Methods】 A recombinant plasmid containing the target protein was constructed, and then the positive bacmid was screened out by the blue and white spots experiment. The verified bacmid was transfected into SF9 insect cells to obtain recombinant baculovirus. The virus was amplified, and the titer level was detected by virus plaque assay. Finally, Western blotting was used to identify the expression of the recombinant protein and optimize the expression conditions. 【Results】 During the construction of the protein expression system, PCR identification and sequencing results confirmed the correctness of the sequences of the recombinant plasmid and the recombinant bacmid. After the transfection of the bacmid, the signs of virus budding were observed in sf9 cells. The virus was collected and amplified. The titer of P1 generation virus was 2×107 pfu/m according to the plaque assay. The recombinant protein was identified by Western blotting and confirmed to be exogenous into the culture medium. The optimal condition for virus infection and protein expression was 72 h after the infection when the multiplicity of infection (MOI) was 1. 【Conclusion】 We constructed an insect cell expression system secreting TSHR 22-289 (55 ku), and the protein could be successfully glycolyzed. This system provides a preliminary basis for the construction and production of its industrial platform and also provides a useful tool for studies on TSHR protein and prevention of GO in the future.
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Objective Production of autotoxin protein in sf9 insect cells with biological activity. Methods Autotaxin cDNA was cloned into pFastBacTMHTA from melanoma cell by extraction of total RNA using TRIzol method and RT-PCR. Bacmid-ATX is isolated from transformed competent bacterial DH10 which carries Bac genomic sequences and transfected into sf9 using lipofectamine 2000. Recombinant ATX virus was amplified in sf9 and further used for infection and expression of ATX protein. Two step purification product using HistrapTMHP and Hiload 16/600 Suerdex 200pg was determined for lysophospholipase D (lysoPLD) activity. Results Correct insertion of PCR fragment is confirmed by BamH I/Xho I digestion and sequencing. ATX virus can infect sf9 and induced enzymatic activity. Column purification and SDS-PAGE resulted 95% in purity and 6mg/liter in yield with significant lysoPLD activity. Conclusion ATX Baculovirus was successfully constructed that can infect sf9 cells and express active lysoPLD. Production of active ATX can be used for crystalography studies and screening for small pharmaceutical inhibitors.
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Objective@#To express envelope protein of ZIKA virus in baculovirus expression system.@*Methods@#Full-length E gene of ZIKA virus was obtained by DNA synthesis and inserted into vector pFastBac1. The constructed recombinant baculovirus transfer vector pFB1-E was transformed to competent DH10Bac cells. The obtained skeleton plasmid rBacmid-E was transfected to sf9 cells, and the constructed recombinant baculovirus rBac-E was determined for titer, for insertion of E gene by PCR, and for expression of E protein by IFA and Western blotting.@*Results@#PCR proved that skeleton plasmid rBacmid-E was constructed correctly. The titer of rBac-E of passage 3 was 2.58×105pfu/ml. The genome of infected cells virus was extracted, the gene band at length of 3 830 bp was observed after PCR amplification. Indirect immunofluorescence of the infected cells showed the specific green fluorescence, 55×103specific band was determined by Western blotting identification in the cell pellet of the infected recombinant baculovirus rBac-E.@*Conclusions@#The recombinant baculovirus with E gene of ZIKA virus was successfully constructed, which laid a foundation of further study on the function of E protein and the vaccine of ZIKA virus.
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Hepcidin is the primary regulatory hormone responsible for lowering the iron content in the blood circulation. Due to its biodegradability and low cytotoxicity, hepcidin is considered as an alternative for iron chelators. The baculovirus expression system may be suitable for human hepcidin production because the expressed proteins generally exhibit proper folding, post-translational modifications, and oligomerization. Using data from two vector maps, pFastBac1 and pFastBac HTB, a unique vector was designed encoding human hepcidin-25 as fusion recombinant peptide. Expression analysis showed that it was expressed as a peptide with a molecular weight near to 5 kDa. After purification and TEV treatment, findings revealed that recombinant human hepcidin-25 was functional and its effect was dose dependent (P=0.001). It was concluded that baculovirus expression was a suitable expression system for production of functional recombinant human hepcidin-25.
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Objective:To express mycobacterium tuberculosis protein MPB 64 in baculovirus insect cell expression system ,and identify its immunogenicity.Methods:The target gene MPB64 was connected to pFastBac vector ,then the pFastBac-MPB64 plasmid which was harvested would transformed to DH10Bac competent,and the target gene was transposition into Bacmid by Tn7 transposase fragment,therefore Bacmid-MPB64 Shuttle vector was obtained.The shuttle vector was packaged by liposomes and transfected Sf 9 cells to harvest P1-generation virus ,then high titers of P4 generation virus was harvested by repeat transfected Sf 9 cells three times.The target protein MPB64 was purified from the supernatant by Q Sepharose FF and Ni affine chromatography ,which were used to immunize BALB/c mice.Antibody changes in serum would be detected ,and the proliferation of immunized mice spleen cells would be detected by MTT,detected the IFN-γsecretion by MPB64 stimulated spleen cells by ELISA method.Results: MPB64 successfully expressed in insect cells.The purity of target protein was over 90% and yield up to 35 mg/L after purification.Purified protein can effectively stimulate BALB/c mice to produce antibodies , increase the content of IFN-γmedium in mice spleen cells ,and significantly promoting proliferation in spleen cells between 0.2-100 μg/ml.Conclusion: MPB64 which has immunogenicity was successfully expressed in baculovirus insect cell expression system ,that open a new avenue for tuberculosis vaccine production.
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BmPLV-Z is the abbreviation for Bombyx mori parvo-like virus (China isolate). This is a novel virus with two single-stranded linear DNA molecules, viz., VD1 (6543 bp) and VD2 (6022 bp), which are encapsidated respectively into separate virions. Analysis of the deduced amino acid sequence of VD1-ORF4 indicated the existence of a putative DNA-polymerase with exonuclease activity, possibly involved in the replication of BmPLV-Z. In the present study, a recombinant baculovirus was constructed to express the full length of the protein encoded by the VD1-ORF4 gene (3318 bp). In addition, a 2163-bp fragment amplified from the very same gene was cloned into prokaryotic expression vector pET-30a and expressed in E.coli Rosetta 2 (DE3) pLysS. The expressed fusion protein was employed to immunize New Zealand white rabbits for the production of an antiserum, afterwards used for examining the expression of the protein encoded by VD1-ORF4 gene in Sf-9 cells infected with recombinant baculovirus. Western blot analysis of extracts from thus cells infected revealed a specific band of about 120 kDa, thereby indicating that the full length protein encoded by the VD1-ORF4 gene had been successfully and stably expressed in Sf-9 cells.
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To obtain the P8 protein of Rice gall dwarf virus (RGDV) with biological activity, its outer coat protein gene S8 was expressed in Spodoptera frugiperda (Sf9) insect cells using the baculovirus expression system. The S8 gene was subcloned into the pFastBacTM1 vector, to produce the recombinant baculovirus transfer vector pFB-S8. After transformation, pFB-S8 was introduced into the competent cells (E. coli DH10Bac) containing a shuttle vector, Bacmid, generating the recombinant bacmid rbpFB-S8. After being infected by recombinant baculovirus rvpFB-S8 at different multiplicities of infection, Sf9 cells were collected at different times and analyzed by SDS-PAGE, Western blotting and immunofluorescence microscopy. The expression level of the P8 protein was highest between 48-72 h after transfection of Sf9 cells. Immunofluorescence microscopy showed that P8 protein of RGDV formed punctate structures in the cytoplasm of Sf9 cells.
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Objective To establish stable insect cell line expressing mIL4 on the basis of construction of inset expression vector pIZT/V5-His.Methods Amplified mIL-4 and pIZT/V5-His were treated with EcoRI and XbaI,and mIL-4 were ligated into pIZT/V5-His vector using T4 DNA ligase.Sf9 cells were transfected with recombinant DNA and ELISA was employed to detect soluble mIL-4 production by transfected Sf9 cells.Results Transfected Sf9 cells could significantly produce mIL4(1 mg?L~(-1)) compared!with control group(0.003 mg?L~(-1)).Conclusion Inset expression vector pIZT/V5-His is an ideal expression vector for mIL-4 production in transfected cells.
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Objective To construct recombinant baculovirus expression vector containing hepatitis C virus(HCV) truncated core gene and EGFP gene,and to study the antigenicity of the fusion protein expressed in Sf 9 cells.Methods PCR-amplified HCV truncated core gene and EGFP gene were cloned into the transposed vector pFastBac1 to construct a recombinant plasmid pFastCt-EGFP,by which E.coli DH10Bac was transformed to get the recombinant BacmidCt-EGFP.Insect Sf 9 cells were transfected with BacmidCt-EGFP and the expression of fusion protein Ct-EGFP was screened by SDS-PAGE and Western blotting.Results SDS-PAGE and Western blot analysis showed that fusion protein Ct-EGFP was expressed with the molecular mass of 40 kD.ELISA results showed that the fusion protein reacted with 15 of 28(54%) anti-HCV positive sera.Conclusion The fusion protein Ct-EGFP was expressed in insect Sf9 cells and showed partial antigenicity.