• BMB Reports
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• v.28 no.6
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• pp.504-508
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• 1995

The electrophoretic patterns of plasma membrane surface proteins of normal rat liver cells and rat hepatomas were compared in 10% non-denaturing and 7-15% gradient non-denaturing gel. Chemical carcinogens, 2-Me DAB (2-methyl-4-dimethylaminoazobenzene) and DENA (diethylnitrosamine), were used to induce hepatoma in rats. One protein which disappeared in hepatoma was identified in normal rat liver by non-denaturing gel electrophoresis. Rabbit antisera were raised against this specific protein, and the protein was purified by Sephacryl S-200 column and immunoaffinity chromatography using the purified antibody. The purified protein showed two bands of molecular weights approximately 50 $kD_{\alpha}$ and 52 $kD_{\alpha}$ by SDS-polyacrylamide gel electrophoresis, which reacted specifically with the antibody. However only one band was observed in non-denaturing gel and also in isoelectric focusing with a pI value of 6.6. This study showed the existence of an unique protein on the plasma membrane surface of normal rat liver cells which disappeared in rat hepatomas induced by chemical carcinogens.

• Journal of Veterinary Science
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• v.19 no.6
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• pp.817-826
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• 2018

The bursa of Fabricius (BF) is a central humoral immune organ unique to birds. Four bursal peptides (BP-I, BP-II, BP-III, and BP-IV) have been isolated and identified from the BF. In this study, the immunoadjuvant activities of BPs I to IV were examined in mice immunized with H9N2 avian influenza virus (AIV) vaccine. The results suggested that BP-I effectively enhanced cell-mediated immune responses, increased the secretion of Th1 (interferon gamma)- and Th2 (interleukin-4)-type cytokines, and induced an improved cytotoxic T-lymphocyte (CTL) response to the H9N2 virus. BP-II mainly elevated specific antibody production, especially neutralizing antibodies, and increased Th1- and Th2-type cytokine secretion. BP-III had no significant effect on antibody production or cell-mediated immune responses compared to those in the control group. A strong immune response at both the humoral and cellular levels was induced by BP-IV. Furthermore, a virus challenge experiment followed by H&E staining revealed that BP-I and BP-II promoted removal of the virus and conferred protection in mouse lungs. BP-IV significantly reduced viral titers and histopathological changes and contributed to protection against H9N2 AIV challenge in mouse lungs. This study further elucidated the immunoadjuvant activities of BPs I to IV, providing a novel insight into immunoadjuvants for use in vaccine design.

• Journal of Microbiology and Biotechnology
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• v.23 no.9
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• pp.1308-1321
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• 2013

The emergence of microcarrier technology has brought a renewed interest in anchorage-dependent cell culture for high-yield processes. Well-known in vaccine production, microcarrier culture also has potential for application in other fields. In this work, two types of microcarriers were evaluated for small-scale monoclonal antibody (mAb) production by CHO-K1 cells. Cultures (5 ml) of microporous Cytodex 3 and macroporous CultiSpher-S carriers were performed in vented conical tubes and subsequently scaled-up (20 ml) to shake-flasks, testing combinations of different culture conditions (cell concentration, microcarrier concentration, rocking methodology, rocking speed, and initial culture volume). Culture performance was evaluated by considering the mAb production and cell growth at the phases of initial adhesion and proliferation. The best culture performances were obtained with Cytodex 3, regarding cell proliferation (average $1.85{\pm}0.11{\times}10^6$ cells/ml against $0.60{\pm}0.08{\times}10^6$ cells/ml for CultiSpher-S), mAb production ($2.04{\pm}0.41{\mu}g/ml$ against $0.99{\pm}0.35{\mu}g/ml$ for CultiSpher-S), and culture longevity (30 days against 10-15 days for CultiSpher-S), probably due to the collagen-coated dextran matrix that potentiates adhesion and prevents detachment. The culture conditions of greater influence were rocking mechanism (Cytodex 3, pulse followed by continuous) and initial cell concentration (CultiSpher-S, $4{\times}10^5$ cells/ml). Microcarriers proved to be a viable and favorable alternative to standard adherent and suspended cultures for mAb production by CHO-K1 cells, with simple operation, easy scale-up, and significantly higher levels of mAb production. However, variations of microcarrier culture performance in different vessels reiterate the need for optimization at each step of the scale-up process.

• Journal of Microbiology and Biotechnology
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• v.18 no.6
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• pp.1186-1190
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• 2008

Single-chain Fv (scFv) antibody against c-Met is expected to be employed in clinical treatment or imaging of cancer cells owing to the important biological roles of c-Met in the proliferation of malignancies. Here, we show that the productivity of scFv against c-Met in Escherichia coli is significantly influenced by the orientation of its variable domains. We generated anti-c-Met scFv antibodies with two different domain orders (i.e., $V_L$-linker-$V_H$ and $V_H$-linker-$V_L$), expressed them in the cytoplasm of E. coli trx/gor deleted mutant, and compared their specific activities as well as their productivities. Productivity of total and functional anti-c-Met scFv with $V_H/V_L$ orientation was more than five times higher than that with $V_L/V_H$ format. Coexpression of DsbC enhanced the yield of soluble amounts of anti-c-Met scFv protein for both constructs. The purified scFv antibodies of the two different formats exhibited almost the same antigen-binding activities. We also compared the productivities and specific activities of anti-c-Met diabodies with $V_H/V_L$ or $V_L/V_H$ formats and obtained similar results to the case of scFv antibodies.

• Journal of Sensor Science and Technology
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• v.16 no.6
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• pp.441-448
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• 2007

In this study, the fiber-optic fluoro-immunosensor was designed to detect foodborne pathogens. The fabricated system is composed of the multimode optical fiber on which antibodies are immobilized. Then, a sandwich immunoassay is applied to the fabricated the fiber-optic fluoro-immunosensor. In the "sandwich" binding format, a primary or "capture" antibody is immobilized on the core surface of the multimode optical fiber and a secondary or named as "tracer" antibody is added to the bulk solution. A tracer is labeled FITC (fluorescein isothiocyanate; ${\lambda}ex$=492 nm, ${\lambda}em$= 520 nm). Different concentrations of antigens are tested in different fibers. The detection limit of the fabricated system is 5.08×103 cfu/ml for Vibrio antigen and $0.1{\mu}g/ml$, $0.05{\mu}g/ml$ in non-labeled monolayer phosphate buffered saline (NMP), non-labeled monolayer carbonate bicarbonate buffer (NMC), respectively.

• Journal of Microbiology and Biotechnology
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• v.32 no.10
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• pp.1335-1343
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• 2022

COVID-19 is an emerging disease that poses a severe threat to global public health. As such, there is an urgent demand for vaccines against SARS-CoV-2, the virus that causes COVID-19. Here, we describe a virus-like nanoparticle candidate vaccine against SARS-CoV-2 produced by an E. coli expression system. The fusion protein of a truncated ORF2-encoded protein of aa 439~608 (p170) from hepatitis E virus CCJD-517 and the receptor-binding domain of the spike protein from SARS-CoV-2 were expressed, purified and characterized. The antigenicity and immunogenicity of p170-RBD were evaluated in vitro and in Kunming mice. Our investigation revealed that p170-RBD self-assembled into approximately 24 nm virus-like particles, which could bind to serum from vaccinated people (p < 0.001) and receptors on cells. Immunization with p170-RBD induced the titer of IgG antibody vaccine increased from 14 days post-immunization and was significantly enhanced after a booster immunization at 28 dpi, ultimately reaching a peak level on 42 dpi with a titer of 4.97 log₁₀. Pseudovirus neutralization tests showed that the candidate vaccine induced a strong neutralizing antibody response in mice. In this research, we demonstrated that p170-RBD possesses strong antigenicity and immunogenicity and could be a potential candidate for use in future SARS-CoV-2 vaccine development.

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.232-232
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• 2005

• BMB Reports
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• v.28 no.3
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• pp.232-237
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• 1995

Arginase was purified to homogeneity from Schizosaccharomyces pombe. The purified enzyme is a tetramer with a subunit molecular weight of 42,000. Activity is optimal at pH 10.0 and at $60^{\circ}C$ The enzyme migrated during isoelectric focusing showing a pl=5.4. The enzyme exhibited hyperbolic kinetics at pH 10.0 with an apparent $K_m$ for L-arginine of 18 mM. Arginase activity was strongly inhibited by L-glutamate.

• Bulletin of the Korean Chemical Society
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• v.24 no.1
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• pp.126-128
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• 2003

• 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.