ABSTRACT
Objective:To express the glycoprotein D of herpes simplex virus type 2 (gD2) in the insect cells,and to determine its immunogenicity.Methods:HSV-2 genome was used as the template for amplification of gD2 extracellular domain fragment gene by PCR.The PCR product was inserted into the vector Bacmind,and the constructed recombinant plasmid gD2-Bacmind was transfected into the sf9 cells to package the recombinant baculovirus.The Sf9 cells were infected by recombinant baculovirus seed derived from the forth passage(P4),the titer of P4 recombinant baculovirus was detected by a plaque assay and the expression of recombinant protein gD2 was determined by Western blotting method.The supernatant of infected cells was collected and purified by Ni-NTA affinity chromatography to obtain the target protein gD2,the purified gD2 protein was used to immunize the BALB/c mice in 0, 2, 4 weeks (gD2 group),and PBS was used as negative control(PBS group);the titers of gD2 specific IgG in serum were detected by ELISA assay.Results: The PCR analysis and sequencing results proved that gD2-Bacmind was constructed correctly.The titer of recombinant baculovirus was 2.0×109 pfu·mL-1,the purified gD2 was about 37 000 with expectation,the percentage of gD2 in total protein was 90%.The average value of Log10 of titer of gD2 specific IgG in serum detected by ELISA assay in gD2 group at the sixth week was 4.34,and there was significant difference compared with PBS group(P<0.01).Conclusion: The gD2 expressed by insect-baculovirus expression vector system has the immunogenicity and can be selected as candidate protein for HSV-2 vaccine.
ABSTRACT
Objective:To construct I-Ad/IgG2b Fc baculovirus expression vector and express I-Ad/IgG2b Fc dimer fusion protein in Sf9 insect cells.Methods:I-Ad α,I-Ad β and IgG2b Fc gene sequences were amplified from BALB/c mouse lymphocytes by RT-PCR.I-Ad α and I-Ad β were connected with the leucine zipper sequence Fos and Jun respectively by overlapping PCR to form I-Ad α-Fos and I-Ad β-Jun.I-Ad α-Fos and IgG2b Fc fragments were ligated by restriction sites Xba I to form I-Ad α-Fos-IgG2b Fc recombination sequence.I-Ad α-Fos-IgG2b Fc and I-Ad β-Jun fragments were inserted to PPH and PP10,which were the downstream of the promoters in the plasmid pFastBacTMDual,to form pFastBacTMDual+[I-Ad/IgG2b Fc] recombinant plasmids.The constructed vector was identified by PCR,restriction endonuclease and sequencing.The recombinant plasmids pFastBacTMDual+[I-Ad/IgG2b Fc] was transferred into the DH10Bac competent cell to form recombinant baculovirus Bacmid+[I-Ad/IgG2b Fc].The recombinant baculovirus was transfected into Sf9 insect cells by liposome transfection reagent.After infected with Sf9 insect cells,the supernatant was collected and concentrated by PEG20000 to obtain I-Ad/IgG2b Fc dimer fusion protein.The fusion protein was detected by double-antibody sandwich ELISA and Western blot.Results:PCR,restriction enzyme digestion and sequencing confirmed that the recombinant vector pFastBacTMDual+[I-Ad/IgG2b Fc] had the correct sequence.The double antibody sandwich ELISA and Western blot showed that recombinant bacmid could successfully infect Sf9 insect cells,and the expressed fusion protein had the correct conformation.Conclusion:The pFastBacTMDual+[I-Ad/IgG2b Fc] baculovirus expression vector was successfully constructed and expressed in Sf9 insect cells,laying a foundation for the study of I-Ad-restricted T cells.
ABSTRACT
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.
ABSTRACT
A baculovirus expression vector system (BEVS) is used routinely to produce recombinant proteins in the milligram scale. Dual Ig domain containing cell adhesion molecule (DICAM) belongs to the type I class of transmembrane proteins. It consists of a signal peptide, two V-type Ig domains in the extracellular region, and a short cytoplasmic tail of 442 amino acids. To purify the recombinant DICAM protein from cells overexpressing the mouse full-length DICAM gene, recombinant baculovirus is infected and recovered in the Sf9 cells. As a result, mouse DICAM protein was efficiently expressed and extracted from the insect cells using the BEVS. This recombinant protein can be used in further studies for functional test of DICAM protein in the cells.