• BMB Reports
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• v.33 no.6
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• pp.440-447
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• 2000

In this study HepG2 cells were used to express and purify HBV pol proteins. In order to facilitate purification of HBV pol proteins, HBV pol and its deletion mutants were fused to MBP (Maltose Binding Protein). As a result we successfully expressed and partially purified both wild type and mutant recombinant HBV pol proteins by using an amylose resin and anti-MBP antibody. In the case of wild type, the anti-MBP antibody detected three bands. One was full-length and the others were generated by proteolysis of the terminal domain region. The expressed MBP/POL proteins were localized both in the cytoplasm and in the perinuclear region. The purified proteins had polymerase activity toward an exogenous homo-polymer template. The MBP/POL protein also had DNA synthesis activity in vivo, since the MBP/POL expression construct was able to complement a HBV polymerase mutant in trans.

• BMB Reports
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• v.42 no.11
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• pp.731-736
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• 2009

The generation of functional recombinant antibodies from hybridomas is necessary for antibody engineering. However, this is not easily accomplished due to high levels of aberrant heavy and light chain mRNAs, which require a highly selective technology that has proven complicated and difficult to operate. Herein, we attempt to use an alkaline phosphate (AP)-fused form of single-chain variable fragment (scFv) for the simple identification of a hybridoma-derived, functional recombinant antibody. As a representative example, we cloned the scFv gene from a hybridoma-producing mouse IgG against branched-chain keto acid dehydrogenase complex-E2 (BCKD-E2) into an expression vector containing an in-frame phoA gene. Functional recombinant antibodies were easily identified by conventional enzyme-linked immunosorbent assay (ELISA) by employing scFv-AP fusion protein, which also readily serves as a valuable immuno-detective reagent.

• Korean Journal of Veterinary Research
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• v.37 no.3
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• pp.547-554
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• 1997

Galectin-3 is known as an animal ${\beta}$-galactoside-binding lectin charicterized with S-type carbohydrate recognition domain. It plays a role in growth, adherence and movement of cells. It is, also, related to the cell transformation and metastasis of tumor cells. In this study, we have expressed and purified recombinant human galectin-3 (rHgalectin-3) using E coli system and asialofetuin affinity chromatography for the future development of monoclonal antibody to Hgalectin-3, which is suggested as the tumor marker for the gastric and thyroid gland cancers. Expressed protein was confirmed as the Hgalectin-3 by immunoblot with cross-reactive murine monoclonal antibody. Lectin activity and specificity of purified protein were, also, confirmed by the competitive inhibition with galectin-3 specific carbohydrate, lactose. Like physiological galectin-3, lectin activity of the molecule was not changed in nonreduced condition. Dimer formation, furthermore, was observed at high concentration of the protein even in the reduced condition, which is well known in physiological galectin-3. These results showed purified rHgalectin-3 has the same activity and molecular nature compared to the physiological galectin-3.

• YAKHAK HOEJI
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• v.55 no.1
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• pp.16-21
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• 2011

HER-2 (Human Epidermal Growth Factor Receptor-2) is a protein giving higher aggressiveness in human breast cancers. Trastuzumab is a monoclonal antibody that targets HER-2 and is known to extend survival across all stages of HER2-positive breast cancer. In this study, we attempted to development of a quantitative ELISA (Enzyme-Linked ImmunoSorbent Assay) for evaluating anti HER-2 antibodies using human HER-2 recombinant proteins to support antibody producing processes and pharmacokinetic studies. We established direct or indirect ELISA method for the trastuzumab-like protein combined human recombinant HER-2. The ELISA method will prove to be great value in quantitating anti-HER-2 antibodies levels for developing anticancer antibodies.

• KSBB Journal
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• v.31 no.1
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• pp.33-39
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• 2016

Developing the method for the selection of animal cell line producing therapeutic monoclonal antibody (mAb) is invaluable as its market is rapidly growing. Although the quality of produced mAb is as important as quantity, however there is no method developed for the selective screening of cell lines on the basis of both quantity and quality. From recent reports, the ratio of light and heavy chain mRNAs of mAb in the cell is a key parameter for the indication of product quality. Therefore, it is obvious that developing the novel method that can detect both light and heavy chain mRNAs in single live cell will provide unprecedented opportunities in bio-industry. Here, we have constructed oligonucleotide probes, molecular beacons for the detection of light or heavy chain mRNAs, respectively, in the live cells producing mAbs. Both beacons showed increased fluorescent intensity after transient transfection of plasmid expressing mAbs analyzed by fluorometer. Flow cytometric analysis clearly demonstrated that both molecular beacons can simultaneously detect the expression of light and heavy chain mRNAs of mAb in the same cell. The technique described in the thesis provides the new direction and concept for developing the method for the smart selection of cell lines producing recombinant proteins including therapeutic mAbs.

• The Plant Pathology Journal
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• v.32 no.5
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• pp.452-459
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• 2016

The genomic region of Grapevine fanleaf virus (GFLV) encoding the movement protein (MP) was cloned into pET21a and transformed into Escherichia coli strain BL21 (DE3) to express the protein. Induction was made with a wide range of isopropyl-${\beta}$-D-thiogalactopyranoside (IPTG) concentrations (1, 1.5, and 2 mM) each for duration of 4, 6, or 16 h. However, the highest expression level was achieved with 1 mM IPTG for 4 h. Identity of the expressed protein was confirmed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) followed by Western blotting. The expressed 41 kDa protein was purified under denaturing condition by affinity chromatography, reconfirmed by Western blotting and plate-trapped antigen enzyme-linked immunosorbent assay (PTA-ELISA) before being used as a recombinant antigen to raise polyclonal antibodies in rabbits. Purified anti-GFLV MP immunoglobulines (IgGs) and conjugated IgGs detected the expressed MP and GFLV virions in infected grapevines when used in PTA-ELISA, double antibody sandwich-ELISA, and Western blotting. This is the first report on the production of anti-GFLV MP polyclonal antibodies and application for the virus detection.

• Molecules and Cells
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• v.27 no.5
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• pp.577-582
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• 2009

The development of a high-throughput functional genomic screening provides a novel and expeditious approach in identifying critical genes involved in specific biological processes. Here we describe a cell-based cDNA screening system to identify the transcription activators of BiP, an endoplasmic reticulum (ER) chaperone protein. BiP promoter contains the ER stress element which is commonly present in the genes involved in unfolded protein response (UPR) that regulates protein secretion in cells. Therefore, the positive regulators of BiP may also be utilized to improve the recombinant protein production through modulation of UPR. Four BiP activators, including human UDP-glucose:glycoprotein glucosyltransferase 1 (HUGT1), are identified by the cDNA screening. Overexpression of HUGT1 leads to a significant increase in the production of recombinant erythropoietin, interferon ${\gamma}$, and monoclonal antibody in HEK293 cells. Our results demonstrate that the cDNA screening for BiP activators may be effective to identify the novel BiP regulators and HUGT1 may serve as an ideal target gene for improving the recombinant protein production in mammalian cells.

• The Journal of Korean Society of Virology
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• v.26 no.2
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• pp.163-171
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• 1996

The recombinant pseudorabies virus major capsid protein (rMCP) was produced by expression of the MCP gene in Sf-9 cell using baculovirus transfer vector system. Following evaluation of the immunochemical properties of the rMCP, the immunogenicity of the recombinant subunit protiens were investigated in guinea pig and swine to obtain the preliminary guide line for the subunit vaccine using rMCP and gP50. It was proved that ultrasonication and 30% ammonium sulfate was most efficient to concentrate and purify the protein. The rMCP was safe in mice, guinea pigs and piglets. In guinea pigs, rMCP mixed with various adjuvants induced substantial degree of serum neutralizing antibody titers, but revealed incomplete protectivity against challenge. In swine, the combination of rMCP and gP50 showed the higher serum neutralizing antibody titers and cellular immune responses than rMCP alone. However, the protectivity was lower in comparison with the commercial gI-deleted inactivated vaccine. We expect these results to contribute to characterization of MCP gene of Korean isolate of PRV and to ultilize as preliminary information for prodution and evaluation of PRV recombinant subunit vaccines.

• Journal of Microbiology and Biotechnology
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• v.25 no.2
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• pp.280-287
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• 2015

Current influenza vaccines are produced in embryonated chicken eggs. However, egg-based vaccines have various problems. To address these problems, recombinant protein vaccines have been developed as new vaccine candidates. Unfortunately, recombinant proteins frequently encounter aggregation and low stability during their biogenesis. It has been previously demonstrated that recombinantly expressed proteins can be greatly stabilized with high solubility by fusing stabilizing peptide (SP) derived from the C-terminal acidic tail of human synuclein (ATS). To investigate whether SP fusion proteins can induce protective immunity in mice, we produced influenza HA and SP fusion protein using a baculovirus expression system. In in vitro tests, SP-fused recombinant HA1 (SP-rHA1) was shown to be more stable than recombinant HA1 (rHA1). Mice were immunized intramuscularly with baculovirus-expressed rHA1 protein or SP-rHA1 protein ($2{\mu}g/mouse$) formulated with aluminum hydroxide. Antibody responses were determined by ELISA and hemagglutination inhibition assay. We observed that SP-rHA1 immunization elicited HA-specific antibody responses that were comparable to rHA1 immunization. These results indicate that fusion of SP to rHA1 does not negatively affect the immunogenicity of the vaccine candidate. Therefore, it is possible to apply SP fusion technology to develop stable recombinant protein vaccines with high solubility.

• Korean Journal of Environmental Agriculture
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• v.30 no.4
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• pp.390-394
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• 2011

BACKGROUND: Plant expression system for mass production of recombinant proteins has several advantages over other existing expression systems with economical and safety issues. Breast cancer is a cancer originating from breast tissue and comprises almost 25% of all cancers in women world widely. Lewis-Y antigen is difucosylated oligosaccharide and is carried by glycoconjugates at cancer cell surface. In this study, the anti-breast cancer mAb BR55, which recognizes the epitope Lewis-Y, was expressed in the plant expression system. METHODS AND RESULTS: We have developed plant system for production of mAb BR55 with or without KDEL (the ER retention signal). This ER retention signal was attached to C-terminus of protein to help retain the recombinant glycoprotein carrying oligomannose glycans and enhance glycoprotein accumulation. PCR analysis was performed and confirmed the presence of recombinant genes. Western blot validated that the recombinant proteins mAb BR55 with or without KDEL were expressed in transgenic plants, moreover, the expression level of the mAb BR55 with KDEL was higher compared to the mAb BR55 without KDEL. CONCLUSION: These results indicate that KDEL fusion is a good way to produce proteins and plant can be an ideal expression system to obtain proteins and enhance accumulation of proteins.