• Macromolecular Research
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• v.15 no.2
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• pp.100-108
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• 2007

Gene therapy has become a promising strategy for the treatment of genetically based diseases, such as cancer, which are currently considered incurable. A major obstacle in the field of cancer gene therapy is the development of a safe and efficient delivery system for therapeutic gene transfer. Non-viral vectors have attracted great interest, as they are simple to prepare, stable, easy to modify and relatively safe compared to viral vectors. In this review, an insight into the strategies developed for polyethylenimine (PEI)-based non-viral vectors has been provide, including improvement of the polyplex properties by incorporating hydrophilic spacer, poly(ethylene glycol) (PEG). Moreover, this review will summarize the strategies for the tumor targeting. Specifically, a targeted polymeric gene delivery system, PEI-g-PEG-RGD, will be introduced as an efficient gene delivery vector for tumor therapy, including its functional analysis both in vitro and in vivo.

• Macromolecular Research
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• v.15 no.3
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• pp.195-201
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• 2007

Non-viral vectors, including lipid- or polymer-based systems, have attracted much attention to date as a gene delivery vehicle, due to safety issues with viral vectors. Chitosan, a naturally existing cationic polymer, has shown great potential as a gene delivery carrier, as it has low immunogenicity and toxicity, excellent transcellular transport ability, and is relatively easy to chemically modify. This review summarizes and discusses the general features of chitosan and its applications as a delivery carrier of DNA and RNA.

• IMMUNE NETWORK
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• v.4 no.3
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• pp.190-197
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• 2004

Background: Rheumatoid arthritis (RA) is an autoimmune disorder characterized by chronic synovial inflammation which leads to joint destruction. Gene therapy of RA targets the players of inflammation or articular destruction. However, viral vectors have safety problems and side effects, while non-viral vectors suffer from inefficient gene transfer and fast loss of gene expression. To overcome the limits of non-vial vectors, an EBV-based plasmid which is known to exert prolonged high level gene expression can be used. Methods: pEBVGFP, pEBVIL-10, and pEBVvIL-10 were constructed by cloning GFP, IL-10, and vIL-10 genes into an EBV-based plasmid, respectively. The pGFP was used as a control plasmid. Each constructs were lipofected into HIG-82 rabbit synoviocytes. The expression of GFP was monitored by FACS and confocal microscopy. IL-10 and vIL-10 expressions were measured by ELISA. Results: GFP expression 2 days after transfection was achieved in 33.2% of cells. GFP-expressing cells transfected with pGFP decreased rapidly from 4 days after transfection and disappeared completely by 11 days. Cells transfected with pEBVGFP began to decrease slowly from 4 days. But GFP expression was detected for over 35 days. In addition, HIG-82 cells transfected with pEBVIL-10 ($44.6{\pm}1.5ng/ml$) or pEBVvIL-10 ($51.0{\pm}5.7ng/ml$) secreted these cytokines at high levels. High level cytokine production by hygromycin selection was maintained at least for up to 26 days after transfection. Conclusion: These results suggest that the EBV-based plasmid has a potential to improve non-viral gene transfer system and may be applicable to treat RA without the drawbacks of viral vectors.

• BMB Reports
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• v.30 no.4
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• pp.269-273
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• 1997

Heptocvte-specific expression induced by Hepatitis B virus (HBV) enhancer 2-core gene promoter was examined in various hepatocyte and non-hepatocyte cell lines. using non-viral and retroviral vector systems in which chloramphenicol acetyltransferase (CAT) is used as a reporter. The non-viral plasmid containing the HBV enhancer 2-core promoter exhibited 22 and 66% of CAT activities in hepatoma cell lines. HepG2 and Hep3B, respectively when compared with CAT activity expressed by CMV promoter. The CAT activities, however. were found to be marginal in other tested hepatoma cell lines as well as mouse primary hepatocytes and non-hepatocytes. The HBV enhancer 2 located upstream the CMV promoter did not affect the CMV promoter activity nor provided hepatocyte-specific expression. Transfection of retroviral plasmid DNA containing the HBV enhancer 2-core promoter as an internal promoter exhibited high and specific CAT expression in HepG2 and Hep3B cell lines but the activity value was 5 to 10 fold lower than the non-viral plasmid with identical promoter. These results suggest that the usage of HBV enhancer 2-core promoter for liver specific expression is limited to certain vectors and hepatocyte cell lines.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.292.2-293
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• 2003

In the gene therapy. viral gene delivery systems are limited in use because of several drawbacks like host immune reactions. Hence, non-viral gene delivery systems such as cationic polymers or synthetic gene carriers are being widely investigated to overcome the problems in the use of viral vectors. We synthesized a new conjugate of polyethyleniminet carrying galactose moieties as a targeting ligand for asialoglycoprotein (ASGP) receptors of hepatocytes. (omitted)

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.4
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• pp.489-498
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• 2018

Objective: Foot and mouth disease (FMD) and porcine reproductive and respiratory syndrome (PRRS) are major diseases that interrupt porcine production. Because they are viral diseases, vaccinations are of only limited effectiveness in preventing outbreaks. To establish an alternative multi-resistant strategy against FMD virus (FMDV) and PRRS virus (PRRSV), the present study introduced two genetic modification techniques to porcine cells. Methods: First, cluster of differentiation 163 (CD163), the PRRSV viral receptor, was edited with the clustered regularly interspaced short palindromic repeats-CRISPR-associated protein 9 technique. The CD163 gene sequences of edited cells and control cells differed. Second, short hairpin RNA (shRNAs) were integrated into the cells. The shRNAs, targeting the 3D gene of FMDV and the open reading frame 7 (ORF7) gene of PRRSV, were transferred into fibroblasts. We also developed an in vitro shRNA verification method with a target gene expression vector. Results: shRNA activity was confirmed in vitro with vectors that expressed the 3D and ORF7 genes in the cells. Cells containing shRNAs showed lower transcript levels than cells with only the expression vectors. The shRNAs were integrated into CD163-edited cells to combine the two techniques, and the viral genes were suppressed in these cells. Conclusion: We established a multi-resistant strategy against viral diseases and an in vitro shRNA verification method.

• Proceedings of the Microbiological Society of Korea Conference
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• 2002.10a
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• pp.109-115
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• 2002

Gene therapy is to treat and cure diseases by an introduction of therapeutic genes in defective cells or tissues of human body. Gene delivery system, gene expression system, and therapeutic gene are three core elements for gene therapy. The efficient delivery of therapeutic genes and appropriate gene expression are the crucial issues for therapeutic outcome of gene delivery. Because it can be used in common for the treatment and cure of various diseases, gene delivery system is the most important core element for a successful gene therapy. Viruses are naturally evolved to transfer their genomes into host cells efficiently. This ability has made vectorologists exploit viruses as attractive vehicles for the delivery of therapeutic genes. Viral vectors based on adenovirus (Ad) and adeno-associated virus (AAV) have been often used for gene delivery in laboratory. Ad and AAV vectors derived from human DNA viruses differ greatly in their life cycle, expression level and duration of transgenes, immunogenicity, and vector preparation. Both vectors can be used as effective tools for gene therapy and more recently in functional genomics. Here, the characteristics of Ad and AAV vectors are discussed.

• KSBB Journal
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• v.13 no.6
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• pp.649-655
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• 1998

Hantaviruses are rodent hosts-borne viruses belonging to the family Bunyaviridae, and are etiologic agents for two acute diseases, i.e., Haemorrhagic Fever with Renal Syndrome (HFRS) and Hantavirus Pulmonary Syndrome (HPS). There have been a lot of reports on prophylactic vaccines and diagnostics for the diseases, but most of viral antigens have been prepared by eukaryotic cell culture. Nucleocapsid proteins of Hantaviruses are known as the major viral antigens. Thereby, we prepared nucleocapsid genes of Hantaan virus and Seoul virus by RT-PCR and cloned into plasmid vectors, pET-3a and pKK223-3. Both genes were expressed in Escherichia coli with higher expression level of Seoul viral nucleocapsid protein compared to that of Hantaan in pET-3a. Hantaan viral gene was expressed much higher level in plasmid pET-3a that in pKK223-3. About 30% of expressed nucleocapsid protein was soluble and the rest was remained in insoluble fraction.

• Proceedings of the Korean Society of Toxicology Conference
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• 2003.10b
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• pp.86-86
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• 2003

Gene therapy is a medical intervention based on modification of the genetic material of living cells. Gene transfer usually conducted using bacterial plasmid DNA and/or virus vector to express a specific protein. Gene transfer medicinal products classified as naked nucleic acid, complexed nucleic acid or non-viral vectors, viral vector, and genetically modified cells according to biological origin.(omitted)

• Research in Plant Disease
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• v.9 no.1
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• pp.1-9
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• 2003

The occurrence of potato(Sotanum tuberosum) viral diseases caused by Potato virus X(PVX), Potato virus Y (PVY), Potato leafroll virus(PLRV), Potato vims S(PVS), Potato virus M(PVM), Potato virus A(PVA), Potato virus T(PVT), Alfalfa mosic virus(AIMV), Tobacco mosic virus(TMV), Potato mop top virus(PMTV) Tobacco rattle virus(TRV) and Potato spindle tuber viroid(PSTVd), potato witches' broom phytoplasma, have been identified so far in Korea. Major viral diseases such as PVX, PVY and PLRV had been studied more deeply, however, the others are just identified and only partially characterized since the first study on the relation between PVX nucleic acid and virus protein by Kim in 1961. The most studies on potato viral diseases are mainly focused on the problems of seed potato production. The National Alpine Agricultural Experiment Station(NAAES), since it began its activities in 1961, has given special attention to this problem by doing studies to identify, characterize and control potato virus diseases. This effort resulted in the development of new potato virus detection methods as a basis for elaborating new method of control, such as the production of seed potato free of virus and the selection of new virus-resistant transgenic potatoes. The further studies of potato viral diseases required would be fallowings: the continuous monitoring for the occurrence of identified or not identified potato viruses in Korea, the isolation of resistant viral genes, the development of control method for the non-persistently transmitted viruses like PVY, special vectors such as nematode and fungus transmitted viruses, TRV and PMTV and the development of control methods against potato viral diseases by viral cross protection, therapy, transgenic plant, and the use of the agents or molecules, such as virus inhibitors and antiviral proteins, etc., blocking viral replication.