• Korean Journal of Veterinary Service
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• v.39 no.2
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• pp.117-124
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• 2016

In this study, the virucidal efficacy of a fumigant containing 20% ortho-phenylphenol against classical swine fever virus (CSFV) and porcine reproductive and respiratory syndrome virus (PRRSV) was examined. After each carrier deposited with CSFV and PRRSV suspensions was exposed to the fumigant in a $25-m^3$ test room for 15 h, all carriers were neutralized and diluted, and each diluted suspension was inoculated into each proper cell line. After incubation, CSFV and PRRSV viability in each cell line was examined and 50% tissue culture infectious dose $(TCID_{50})/mL$ was calculated. In the results, the concentration of viable virus in all of pathogen control-carriers was more than $2{\times}10^5TCID_{50}/mL$, and there were no cytotoxicity in all of toxicity control-carriers. In addition, the fumigant inactivated ${\geq}4.8{\log}_{10}(TCID_{50}/mL)$ of both CSFV and PRRSV. These findings will be useful for preventing the spread of CSFV and PRRSV infection.

• Proceedings of the Korean Society of Veterinary Pathology Conference
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• 2003.10a
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• pp.12-12
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• 2003

Several cases of classical swine fever (CSF) were reoccurred in Cheolwon province and Incheon city in 2002. Two isolates (Cheolwon and Incheon) of classical swine fever viruses (CSFV) were successfully isolated and classified into genotype-2 with a phylogenetic analysis [l, 2]. (omitted)

• BMB Reports
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• v.40 no.5
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• pp.611-616
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• 2007

$E^{rns}$ is an envelope glycoprotein of classical swine fever virus (CSFV) and has an unusual feature of RNase activity. In the present study, we demonstrate that $E^{rns}$ counteracts Newcastle disease virus (NDV)-mediated induction of IFN-$\beta$. For this purpose, $E^{rns}$ fused to the enhanced green fluorescent protein (EGFP) was transiently expressed in porcine kidney 15 (PK15) cells. In luciferase activity assay, $E^{rns}$-EGFP was found to prevent IFN-$\beta$ promoter-driven luciferase expression and block the induction of IFN-$\beta$ promoter mediated by NDV in a dose-dependent manner. Through IFN-specific semi-quantitative RT-PCR detection, obvious decrease of IFN-$\beta$ mRNA in NDV-infected PK15 cells was observed in the presence of $E^{rns}$-EGFP. In contrast, EGFP alone showed none of this block capacity. In addition, $E^{rns}$-EGFP mutations with RNase inactivation were also found to block NDV-mediated induction of IFN-$\beta$. These evidences establish a novel function for CSFV $E^{rns}$ glycoprotein in counteraction of the IFN-$\beta$ induction pathway.

• Proceedings of the Korean Society of Veterinary Pathology Conference
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• 2003.10a
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• pp.34-34
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• 2003

Classical swine fever (CSF) is a contagious disease of swine with serious economic losses in pig industry [1]. The disease is caused by CSFV which belongs to the viruses of bovine viral diarrhea (BVDV) and border disease virus (BDV) make up the Pestivirus genus within the family Flaviviridae [2]. Attenuated Korean LOM strains were used in Korea. For these reasons a practical approach for discrimination between vaccine and field strains is needed. Here, we described the deveopment of real-time RT-PCR to discriminate between vaccine strains and Korean field viruses of CSFV. (omitted)

• Journal of Veterinary Science
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• v.23 no.5
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• pp.32.1-32.11
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• 2022

Background: Classical swine fever (CSF) is a severe infectious disease of pigs that causes significant economic losses to the swine industry. Objectives: This study developed a solid-phase blocking enzyme-linked immunosorbent assay (spbELISA) method for the specific detection of antibodies against the CSF virus (CSFV) in porcine serum samples. Methods: A spbELISA method was developed based on the recombinant E2 expressed in Escherichia coli. The specificity of this established spbELISA method was evaluated using reference serum samples positive for antibodies against other common infectious diseases. The stability and sensitivity were evaluated using an accelerated thermostability test. Results: The spbELISA successfully detected the antibody levels in swine vaccinated with the C-strain of CSFV. In addition, the detection ability of spbELISA for CSFV antibodies was compared with that of other commercial ELISA kits and validated using an indirect immunofluorescence assay. The results suggested that the spbELISA provides an alternative, stable, and rapid serological detection method suitable for the large-scale screening of CSFV serum antibodies. Conclusions: The spbELISA has practical applications in assessing the vaccination status of large pig herds.

• Korean Journal of Veterinary Research
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• v.46 no.3
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• pp.197-206
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• 2006

In March 2003, classical swine fever (CSF) infection was reported in a piggery located at Iksan city, Jeollabuk-do in Korea. Subsequently, a total of 72 infected farms were confirmed between March and December, 2003. Based on epidemiological investigation of the earlier confirmed infected farms, the source of infection was shown to be from a breeding farm. Targeted surveillance of 82 piggeries that had acquired pigs from this breeding farm showed 44 piggeries were infected with CSF virus. CSF virus was introduced into this breeding farm by movement of selected breeder pigs from its 12 contracted farms which were located in areas that had been affected by CSF epidemic in late 2002. CSF had then spread through out the country mainly by direct transmission through the sale and movement of pigs from this breeding farm. Consequently, 47 (62%) among 72 CSF affected farms were associated, directly and indirectly, with this breeding farm. This study showed that inadequate control for breeding farms and transport restriction in CSF outbreak areas resulted in the nationwide spread of CSF and the failure of the eradication campaign that has been underway for several years by the Korean animal hygiene authority as well as the fanners. Improvements of control policy through further research of the 2003 CSF epidemic will be needed to reestablish the Korean CSF eradication program in the future.

• Journal of Microbiology and Biotechnology
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• v.25 no.4
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• pp.537-546
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• 2015

Classical swine fever (CSF) is a highly contagious disease of pigs caused by CSF virus (CSFV). E2 is the major viral envelope protein of immune dominance that induces neutralizing antibodies and confers protection against CSFV infection. The B/C domains of E2 are variable among CSFV isolates, which could affect immunogenicity and binding to antibodies. We attempted to characterize the epitope recognized by a monoclonal antibody 2B6 (mAb-2B6) raised against the E2 B/C domains of the vaccine C-strain and to examine if mutations in the epitope region would affect antibody binding and viral neutralization. The epitope specific for mAb-2B6 recognition is linear, spanning five residues ⁷⁷⁴DGXNP⁷⁷⁸ in the B/C domains. The residue N777 is indispensable for the specificity. The epitope exists only in group 1 strains, but not in those of group 2. The recombinant viruses containing individual mutations on the epitope region lost the reactivity to mAb-2B6. The mutant virus RecC-N777S had low replication potential, about 10-fold decrease in the yield of progeny virus particles, whereas the mutant virus RecC-P778A reverted to proline upon continuous passaging. The mutations on the mAb-2B6 epitope region did not affect neutralization by anti-C-strain polyclonal sera from pigs. Deletion from aa774 covering the mAb-2B6 epitope, but not that from aa781, also affected binding with the polyclonal antibodies from vaccinated pigs, although the major binding region for the vaccinated antibodies is aa690-773.

• International Journal of Industrial Entomology and Biomaterials
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• v.29 no.2
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• pp.207-213
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• 2014

The structural proteins of classical swine fever virus (CSFV) consist of nucleocapsid protein C and envelope glycoprotein $E^{rns}$ (E0), E1 and E2. Among them, E2, the most immunogenic of the CSFV glycoproteins, induces a protective immune response in swine. In this study, to determine the optimal expression conditions of glycoprotein E2 using baculovirus system, we investigated the influence of insect cells and media to the expression of recombinant E2. Recombinant virus containing glycoprotein E2 coding gene was constructed with bApGOZA DNA. Expression of the glycoprotein E2 was analyzed by SDS-PAGE and Western blot analysis using anti-CSFV E2 monoclonal antibodies. Expression of glycoprotein E2 in Sf21 cells was first observed after 3 days and reached a maximum on the 5th day after infection. Furthermore, the highest levels of glycoprotein E2 expression were observed at multiplicity of infection (MOI) of 5. When three different insect cell lines (Sf21, High-Five and Se301) were tested, High-Five cells showed the highest production. In addition, four different serum-free and serum-supplemented media, respectively, were tested for the expression of glycoprotein E2 and the budded virus (BV) titers. As a result, serum-supplemented medium provided the best conditions for protein production and the BV yield.

• Microbiology and Biotechnology Letters
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• v.43 no.1
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• pp.22-30
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• 2015

CSF is a major concern for the swine industry, representing currently the most epizootically dangerous disease to the species. Numerous CSFV isolates with various degrees of virulence have already been isolated worldwide, ranging from low virulent strains that do not result in any apparent clinical signs to highly virulent strains that cause a severe per acute hemorrhagic fever with very high mortality. The molecular epidemiology of CSFVs has proven to be an essential tool for effective disease control and the development of safe and effective vaccines. Therefore, this study cloned and sequenced local CSFV isolates, and conducted a phylogenetic analysis based on the E2 glycoprotein encoding sequences.The RNA was extracted from PK15 cell culture passaged CSFV isolates, the cDNA prepared, and the complete E2 gene amplified with a product size of 1186 bp. The gelpurified PCR product was cloned into a pGEMT easy vector and the positive clone commercially sequenced. Aligning the nucleotide (1119 bp) and amino acid (373) sequences with 29 reference strains revealed nucleotide and amino acid sequence identities of 82.60-97.80% and 88.70-98.70%, respectively, indicating a higher mutation rate of the field CSFV strains. The phylogenetic analysis based on the complete E2 amino acid sequences also revealed a reliable differentiation of all the analyzed strains into specific genetic groups and subgroups, plus the local isolate (CSFV-E2) was found to cluster with the CSFV subgroup 2.2. Thus, the full-length E2 cds proved to be most suitable for a reliable and statistically significant phylogenetic analysis of CSFV isolates.

• Korean Journal of Veterinary Service
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• v.26 no.2
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• pp.163-184
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• 2003

This study was conducted to survey the farm which suffered from disease similar to classical swine fever(CSF) in Gyeongbuk province. Clinical signs appeared first in a few number of growing pigs which showed specific signs of diarrhea, depression, sleepiness, and reluctance to get up or to eat. Younger piglets may have appeared chilled, shiver and huddle together. As the disease progresses the affected pig's skin went red and purple. In histopathological signs, there were many haemorrhages throughout the body and larger haemorrhages in some organs such as lymph nodes. And there is a precipitous fall in the number of circulating leukocytes in the blood. In spite of insisting of farmer which did not vaccinate to classical swine fever, significant antibody production was detected in these affected pigs at enzyme-linked immuonsorbent assay. According to the above results at first glance, these affected pig suspected with CSF in clinical signs and histopathological lesions only. Because the symptoms and post-mortem picture were very similar to CSF, these false positive results would have been dangerous to diagnostician. But by reverse transcriptase polymerase chain reaction(RT-PCR) and comparative nucleotide sequence analysis, the disease was correctly diagnosed with post-weaning multisystemic wasting syndrome(PMWS) and porcine reproductive and respiratory syndrome(PRRS) compoundly. And the antigen which were detected the lesion similar to CSF virus, was confirmed with LOM vaccine strain of CSF. In most national CSF eradication program and in countries which are free of the CSF virus, vaccination against CSF is not practiced and generally is not allowed. But now in Korea, routine vaccination is practiced because of outbreaking the CSF repeatedly. When CSF is diagnosed the whole herd and other in contact animal are slaughtered continuously.