Biochemical characterization of the recombinant schistosome tegumental protein SmALDH_312 produced in E. coli and baculovirus expression vector system

BACKGROUND The heterologous expression of parasitic proteins is challenging because the sequence composition often differs significantly from host preferences. However, the production of such proteins is important because they are potential drug targets and can be screened for interactions with new lead compounds. Here we compared two expression systems for the production of an active recombinant aldehyde dehydrogenase (SmALDH_312) from Schistosoma mansoni, which causes the neglected tropical disease schistosomiasis. RESULTS We produced SmALDH_312 successfully in the bacterium Escherichia coli and in the baculovirus expression vector system (BEVS). Both versions of the recombinant protein were found to be active in vitro, but the BEVS-derived enzyme showed 3.7-fold higher specific activity and was selected for further characterization. We investigated the influence of Mg2+, Ca2+ and Mn2+, and found out that the specific activity of the enzyme increased 1.5-fold in the presence of 0.5 mM Mg2+. Finally, we characterized the kinetic properties of the enzyme using a design-of-experiment approach, revealing optimal activity at pH 7.6 and 41C. CONCLUSIONS Although, E. coli has many advantages, such as rapid expression, high yields and low costs, this system was outperformed by BEVS for the production of a schistosome ALDH. BEVS therefore rovides an opportunity for the expression and subsequent evaluation of schistosome enzymes as drug targets

Expression and immunization assessment of HSV-2 glycoprotein D in baculovirus expression vector system / 吉林大学学报(医学版)

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.

Expression, purification and immunogenicity analysis of recombinant MPB64 using baculovirus expression system / 中国免疫学杂志

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.

Mouse Dual Ig Domain Containing Cell Adhesion Molecule Protein Expression and Purification Using the Baculovirus Expression Vector System

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.