• International Journal of Industrial Entomology and Biomaterials
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• v.32 no.2
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• pp.90-97
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• 2016

The major structural proteins of porcine reproductive and respiratory syndrome virus (PRRSV) are derived from ORFs 4, 5, and 6. They have been considered very important to arouse the humoral and cellular immune responses against PRRSV infection and proposed to be the excellent candidate proteins in the design of PRRS bioengineering vaccine. However, the PRRSV structural proteins are produced in low levels in the infected cells because it forms insoluble protein and possesses several transmembrane regions. To overcome this problem, we fused the ORF4, ORF5, and ORF6 with SUMO (small ubiquitin-related modifier). The resulting fusion protein SUMO-ORF4, -ORF5, and -ORF6 were highly expressed in Bm5 cells. The level of protein expression using the Bombyx mori larvae was higher than that using Bm5 cells. In addition, fusion to SUMOstar, which is not processed by native SUMO proteases, significantly enhanced protein expression levels compared to SUMO fusion. This study demonstrated that SUMO or SUMOstar, when fused with PRRSV structural proteins, was able to promote its soluble expression. This may be a better method to produce PRRSV structural proteins for vaccine development.

• Korean Journal of Veterinary Service
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• v.30 no.2
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• pp.197-203
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• 2007

A total of 501 serum samples were selected from blood samples that were submitted to Department of Veterinary Pathology, Kangwon National University from all provinces in Korea from September 2001 to August 2002. Their sera were examined for antibodies to swine influenza virus subtype H1N1 (SlV H1N1) and porcine repro-ductive and respiratory syndrome virus (PRRSV) according to the age of pig, season, and herd size using enzyme-linked immunosorbent assay. The seroprevalence of SIV H1N1, PRRSV, and dual infection were 39.12%, 61.48%, and 25.95%, respectively. The seroprevalence of SIV H1N1 according to herd size was not significant differences (p>0.05). The results showed that the PRRSV infection spread widely in swine herds throughout the country.

• Korean Journal of Veterinary Service
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• v.34 no.2
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• pp.111-116
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• 2011

Artificial insemination (AI) of swine is a very useful reproductive tool and that offers convenience in the Korean swine industry. Since many viruses have been reported to be excreted through boar semen, we investigated the presence of antibodies and antigens against viruses causing reproductive failure in semen of boar in 349 semen samples collected from six Korean AI centers. Viral antigens were detected by polymerase chain reaction (PCR) or reverse transcription-PCR predominantly. The results was as follows. The major reproductive failure causing factor was porcine circovirus type 2 (PCV2), followed by porcine reproductive and respiratory syndrome virus (PRRSV) ($X^2$=166.64, P<0.001). PCV2 and PRRSV, Japanese encephalitis virus (JEV), encephalomyocarditis virus (EMCV) was detected in 73 samples (20.9%), 44 samples (12.6%), 4 samples (1.1%), 3 samples (0.9%), respectively and porcine parvovirus in one sample (0.3%) Classical swine fever virus (CSFV), bovine viral diarrhea virus and Aujeszky's disease virus (ADV) were not detected. Enzyme-linked immunosorbent assay was carried out in 111 serum samples from three AI centers. In most pigs, antibodies response was showed prominently in CSFV (105 sera, 94.6%) ($X^2$=82.580, P<0.001), followed by, in PRRSV (100 sera, 90.1%), PCV2 (92 sera, 90.1%), and PPV (8 sera, 82.9%). ADV antibody was not detected. Thus, the experimental results will be used for the base data, with respect to the state of viral stillbirth in general pig farms, as well as AI centers and breeding farms in Korea.

• Journal of Veterinary Clinics
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• v.30 no.4
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• pp.236-240
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• 2013

A total of 170 litters (575 samples) of aborted and stillbirth fetuses submitted to the Gyeongsangbuk-Do Veterinary Service Laboratory (GVSL) between January 2006 and December 2010 from pig farms in Gyeongbuk province were studied to identify porcine abortion- and stillbirth-associated viruses such as Porcine parvovirus (PPV), Encephalomyocarditis Virus (EMCV), Japanese Encephalitis Virus (JEV), Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), and Aujeszky's Disease Virus (ADV). Virus was not detected by PCR in 36 litters, but viral antibody was detected by HI and ELISA in 93 litters. The majority of etiological viruses were PPV (67 litters, 39.4%), EMCV (50 litters, 29.4%), PRRSV (15 litters, 8.8%), and JEV (11 litters, 6.5%); ADV was not detected by either PCR or ELISA. Single infection occurred in 52 litters (30.6%), co-infection occurred in 41 litters (24.1%), and unknown cases with no detection of any of the five viruses occurred in 77 litters (45.3%).

• Korean Journal of Veterinary Service
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• v.41 no.4
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• pp.263-269
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• 2018

Developing drugs targeting respiratory pathogen is essential to control respiratory diseases. Many experiments have been performed under in vivo situation. However, in vivo experiments have economical and ethical issues. The objective of this study was to determine the possibility of developing an ex vivo lung culture system with possible application for respiratory infection studies. After isolating lungs from naïve pigs, agarose-inflated lung tissues were prepared and sliced manually. These sliced lung tissues were then subsequently placed on 24-well plates. Eight different combinations of media were used to determine the optimum ex vivo lung culture condition. In addition, lung tissues were infected with porcine reproductive and respiratory syndrome (PRRS) virus at a titer of $1{\times}10^4\;TCID_{50}/mL$. Virus growth was confirmed by titration in MARC-145 cells at 2, 4, 6 days post infection (dpi). We found that ex vivo lung culture in physiological environment was not media specific based on histopathology and cytotoxicity. However, under virus-infected condition, thickened alveolar walls in the lung tissues and stable virus titers at 2, 4, 6 dpi were shown in F12K medium suggesting that it was useful for tissue maintenance and virus infection using PRRS virus infected lung tissues. The present study shows the possibility of using porcine ex vivo lung model for respiratory infection studies.

• Korean Journal of Veterinary Service
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• v.36 no.3
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• pp.157-162
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• 2013

A good level of biosecurity practice is important for efficient porcine reproductive and respiratory syndrome (PRRS) control. In the current study, disinfecting ability of ozone against PRRS virus (PRRSV) was evaluated in comparison with ultraviolet (UV) and an organic acid-based disinfectant to assess the possible use of ozone for disinfecting farm vehicles, equipments, and materials to reduce the risk of new virus introduction. For in vitro evaluation, the levels of infectious virus and viral RNA were determined on the swabs collected from the floor surface of each room treated with either ozone, UV or the disinfectant up to 30 min after contamination with 100 mL of VR2332 ($10^5\;TCID_{50}/mL$). For in vivo evaluation, 3, 4-week old, PRRS-free pigs were housed into those rooms right after the last swab collection. Then the pigs in each room were injected intramuscularly with the corresponding swab samples collected at the last time point and pooled per each room. Although ozone, UV, and the disinfectant significantly reduced the levels of PRRSV RNA contamination, ozone was most effective in removing the viral RNA. In addition, the virus collected after at least 10 min exposure to ozone failed to replicate in pigs while the virus collected after treatment with UV and the disinfectant for 30 min still replicated in pigs. Based on the results, it was concluded that ozone is more effective in inactivating PRRSV as compared with UV and the organic acid-based disinfectant.

• 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.

• Korean Journal of Veterinary Research
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• v.39 no.1
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• pp.133-137
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• 1999

The 2,078 blood samples from 148 swine farms were collected and tested by IFA for porcine reproductive and respiratory syndrome(PRRS) virus antibody to know what type of PRRS prevails by the area. Clinically reproductive form of PRRS occurred in swine farms of 3/27, 3/87, and 2/34 in eastern, central and western areas, but the seroprevalence of those areas was different as 6.5%, 23.3%, and 17.6%, respectively. However, respiratory form of PRRS occurred more frequently, and the number of farms manifested with the respiratory form of PRRS in the eastern, central and western areas was 22/27, 71/87, and 30/34, respectively. The seroprevalence of that form of PRRS in the eastern, central and western areas was 52.2%, 67.1%, and 51.6%, respectively. Subsequently mixed form of PRRS occurred more frequently in the central area and the number of farms of eastern, central and western areas was 2/27, 13/87, and 2/34, respectively. The PRRS seroprevalence of the eastern, central and western areas was 58.6%, 54.0%, and 19.2%, respectively. Collectively the PRRS seroprevalence of eastern, central and western areas was 43.8%, 59.3%, and 38.2%, respectively. Overall seroprevalence of PRRS in Korea was 51.8%. In conclusion, the reproductive or the respiratory form of PRRS has been still in trouble in the Korean swine industry and PRRS control measures have to be taken in consideration.

• Korean Journal of Veterinary Service
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• v.22 no.4
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• pp.363-370
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• 1999

Isolation of PRRSV was attempted from 646 swine sera collected from swine farms. The MARC-145 cell, which is highly permissive to PRRSV, was used for virus isolation, propagation, IFA test, and VN test. Total 36 cytopathic viruses to MARC-145 cells were isolated. The virus isolates were identified as a PRRSV by the IFA test and VN test using the reference sera prepared by experimental infection of reference PRRSV CNV-1 into 30 day-old pig. In addition to serological conformation, ORF5 of genomic RNA of 6 selected cytopathic viruses were amplified by the RT-PCR. The resulting PCR products were examined by electrophoresis in 1.2% agarose gel. An appropriate bands of about 680bp including the flanking sequence of total 80bp were seen on agarose gel.

• Journal of Life Science
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• v.19 no.10
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• pp.1451-1455
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• 2009

Porcine cytomegalovirus (PCMV) is a betaherpesvirus which causes reproductive failure in breeding sows and generalized infection in newborn piglets. It has worldwide distribution including Korea. Serological survey on this virus has been reported in 76.3% of pigs, but virological survey and epidemiological analysis on PCMV distribution have been reported in only a few papers in Korea. In this study, we investigated the virological prevalence and infection status of PCMV on a farm level in selected swine farms with respiratory diseases. A total of 1,938 blood samples taken from groups of pigs of different ages were collected from 31 farms distributed nationwide in 2006 and 2007 and tested by PCR to detect the presence of PCMV. Virological prevalence at farm level and pig level were 96.8% and 17.5%, respectively, suggesting that PCMV has endemically infected Korean pig herds. The prevalence at farm level in gilts, sows and suckling piglet groups were 16.7%, 36.7% and 56.7%, indicating that vertical infections frequently occurred in conception or newborn stage. Thereafter, detection rates of PCMV were slightly increased in pig groups aged 40 and 70 days (70.0% and 73.3%), and then gradually decreased as they aged - 33.3% in 100, 26.7% in 130 and 16.7% in 160 day old pig groups. The prevalence at pig level has similar patterns to that at farm level. With the passage of time, the variation of infection patterns of PCMV was investigated in four PCMV-positive farms. Three blood samples were collected at intervals of 6 months in each farm, and examined for presence of PCMV using PCR. The results revealed that once PCMV was introduced to the pig farms, it continuously circulated between and within groups of sows and piglets in those farms. Taken together, it can be concluded that PCMV has endemically infected Korean pig farms and has the potential risk for emerging pathogen in combination with the known endemic pathogens including porcine reproductive, respiratory syndrome virus and porcine circovirus type 2. Therefore, more research is needed on diagnosis, epidemiology and control strategy for PCMV on the field.