• Korean Journal of Veterinary Service
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• v.43 no.4
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• pp.251-256
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• 2020

Two suckling piglets, 4 days and 10 days of age, showed lethargy and dyspnea after birth and mortality had been increased after incoming gilts from breeding farm. At necropsy, the lungs showed diffuse fail to collapse with rubbery consistency, edematous dilatation of interlobular septa, and lobular consolidation with purple red color. Heart was diffuse pale in color and had several irregular linear-shaped macules or patches. Histopathologically, diffuse interstitial pneumonia with the proliferation of type II pneumocytes was present in the lungs of 2 piglets. Alveolar lumens contained necrotic cellular debris derived from neutrophils and macrophages. Multifocal hemorrhage and necrotizing pneumonia with protozoan tachyzoites were observed in the lungs. Severe multifocal to confluent necrotic myocarditis, necrotic encephalitis, and necrotic adrenalitis with intralesional protozoan tachyzoites were observed in piglets. According to immunohistochemical analysis (IHC), Toxoplasma (T.) gondii tachyzoites antigens were confirmed in lung, heart, brain, and adrenal gland. And porcine reproductive and respiratory syndrome virus (PRRSV) antigens were also detected in the cytoplasm of macrophages in lungs using IHC. Based on the gross, histopathologic and immunohistochemical features, two suckling piglets were diagnosed as co-infection of T. gondii and PRRSV.

• Journal of Veterinary Science
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• v.21 no.4
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• pp.68.1-68.8
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• 2020

A fluorescent microsphere-based immunochromatographic strip test (FICT) was developed for the rapid, sensitive, and quantitative detection of porcine reproductive and respiratory syndrome virus (PRRSV) antibodies at the pen-side. The assay was based on the formation of a sandwich immune-complex (anti-pig IgG-PRRSV antibodies-NSP7/N), which was validated by a comparison with IDEXX-ELISA using 3325 clinical specimens. The diagnostic specificity, sensitivity, and accuracy of FICT were 97.28, 93.41, and 94.95%, respectively. FICT showed a good correlation with the virus neutralization assay. Overall, a promising pen-side diagnostic tool was developed for the rapid and quantitative detection of PRRSV antibodies within 15 min.

• Korean Journal of Veterinary Research
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• v.39 no.4
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• pp.760-764
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• 1999

A totoal of 219 pigs, 109 necropsy-pigs at the diagnostic laboratory of Cheju National University and 110 slaughter-pigs in Cheju, were evaluated for the prevalence of tissue antigen and serum antibody for spontaneus porcine reproductive and respiratory syndrome(PRRS). Tissues from 219 pigs examined for PRRS viral antigen by immmunohistochemistry included lung(cranio-ventral lobes and dorso-caudal lobes), tonsil, tracheobronchial lymph node, mesenteric lymph node, heart, kidney, liver, spleen, testis, ovary, brain, and spinal cord. Sera from 180 pigs were tested for the presence of antibody to PRRS virus by the indirect fluorescent antibody assay (IFA). In the examination of serum antibody and tissue antigen for PRRS virus, serum antibody titers were considered as positive in 10%(18/180) of animals tested and PRRS viral antigen was detected in tissues of 4%(9/219) of the pigs. PRRS virus tissue antigen was most commonly detected by immunohistochemistry in the cranio-ventral lobe and tonsil. We also confirmed the distribution of tissue antigen and prevalence of serum antibody to PRRS virus in Cheju. The detection of viral antigen by immunohistochemistry in tonsils and cranio-ventral lobes proved to be a very useful method for PRRS diagnosis.

• Korean Journal of Veterinary Service
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• v.27 no.1
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• pp.89-94
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• 2004

Total 2,451 sera collected from pig farms nationwide were tested for the detection of porcine reproductive and respiratory syndrome(PRRS) virus antibodies. The results were analyzed between different geographic regions, types of breeding pigs, and different years. The overall seroprevalence of PRRS virus antibodies for 3 years was 32.4%(705/2,451). The seroprevalence of PRRS virus antibodies in years 2000, 2001, 2002, and 2004 was 33.4% (284/850), 38.6%(291/754), 33.3%(155/466), and 17.1%(65/381), respectively. The seropevalence of PRRS virus antibody in sow in years 2000, 2001, 2002 and 2003 was 31.7%, 28.4%, 29.6%, and 13.4%, respectively. The seropevalence of PRRS virus antibody in gilts in years 2000, 2001, 2002 and 2003 was 36.6%, 67.4%, 54.7%, and 33.9%, respectively. The seropevalence of PRRS virus antibody in boars in years 2000, 2001 and 2003 was 45.7%, 36.4%, and 100%, respectively. No boar serum sample was submitted for the diagnosis of PRRS virus antibody in the year 2000. High seroprevalence of the PRRS virus antibody in sow, gilts and boars indicates that the infected breeding pigs are the major source of the PRRS virus infection, and also play an important role in spreading the PRRS virus between fan mates or herds.

• Korean Journal of Veterinary Service
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• v.22 no.4
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• pp.371-375
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• 1999

Total 1,434 sera collected from 72 pig farms were tested for the detection of porcine reproductive and respiratory syndrome (PRRS) virus antibodies. The overall seroprevalence of PRRS virus antibodies was 49.3% (707/727). Of 72 farms tested 59 (81.9%) farms had at least one or more than one pigs with PRRS virus antibodies. The seroprevalence of PRRS virus antibody varied with age. Seroprevalence of PRRS virus antibody in 1 to 30-day-old, 31 to 40-day-old, 41 to 50-day-old, 51 to 60-day-old, and over 61-day-old pig were 27.4%, 52.3%, 57.9%, 52.7%, and 68.2%, respectively. Gilt showed relatively higher seroprevalence (61.2%) than sow (29.2%) and boar (38.3%). In most farms, the infection of PRRS virus was chronic and confined to grower or finisher. This pattern of infection suggests that partial depopulation of the infected herds appears be one of the measures to eradicate the PRRS virus infection. High seroprevalence of the PRRS virus antibody in gilts and boars indicates that the infected gilts and boars in the breeding farms are the major source of the PRRS virus infection, and also play an important role in spreading the PRRS virus between fan mates or herds.

• 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 Research
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• v.46 no.4
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• pp.363-370
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• 2006

Porcine reproductive and respiratory syndrome (PRRS) is an economically important disease of swine that occurs all over the swine industry worldwide. It was first observed in the Unite States in 1987 then in Europe in 1990. It has been described in Japan and in Korea in 1993. PRRS virus is divided into two distinct types, North American and European, genetically. Based on our limited knowledge there has been no report on the existence of European PRRSV. But according to the government's Korea Customs Service there has been many importations of breeding pigs from Europe. These seem to make an estimate that European PRRSV could be introduced in Korea by inflow of European breeding pigs. We first detected the European PRRSV could be introduced in Korean pig farms by using polymerase chain reaction (PCR). Further, it is also identified that there are not only North American PRRSV antibody but also a European PRRSV antibody. According to the genetical and serological experiment results, the presence of established North American PRRSV in Korea is due to the use of live vaccines made of North American PRRSV strain as well field virus infection, and the European PRRSV is possibly introduced from imported breeding stock.

• Korean Journal of Veterinary Service
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• v.42 no.4
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• pp.201-216
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• 2019

Porcine reproductive and respiratory syndrome (PRRS) is characterized by reproductive failure in sows and respiratory distress in all age pigs. Porcine respiratory disease complex (PRDC) is a disease caused by opportunistic bacterial infection secondary to a weakened immune system by a preceding respiratory infection. In this study, we tried to compare the immune responses in PRRS and PRDC groups to clearly characterize the disease severity. Eighty-five pigs were infected with various Korean field PRRS virus strains. Infected animals were classified into PRRS (n=32) and PRDC (n=53) groups based on lung lesions such as interstitial pneumonia, suppurative pneumonia, and pleuropneumonia. The immune cell population of bronchoalveolar lavage cells (BALc) was evaluated on 14 and 28 days post infection (dpi) and PMBC cytokine expression was measured on 0, 3, 7, 14 dpi to investigate early inflammatory reactions. Pulmonary lesion severity was negatively correlated with alveolar macrophage (AM) in both PRRS and PRDC groups on 14 and 28 dpi. AM in BALc was less populated in PRDC group on 28 dpi compared to PRRS group. AM in BALc was significantly less populated in PRDC group on 28 dpi compared to 14 dpi. In addition, cytotoxic T lymphocyte (CTL) in BALc was higher populated in PRDC group on 14 dpi and 28 dpi compared to PRRS group. In the case of PBMC cytokine TNF-α, IFN-α, IL-1β, IFN-γ, FoxP3, and IL-2, the PRRS group showed higher expression than the PRDC group on 7 dpi, 14 dpi, 7 dpi, 14 dpi, 14 dpi, and 14 dpi, respectively. On the other hand, in the case of IFN-β, IL-6, IL-8, IL-4, and IL-17, the PRDC group showed higher PBMC cytokine expression at 14 dpi, 7 dpi, 14 dpi, 3 dpi, and 3 dpi, respectively, than the PRRS group. Based on these results, our study could characterize differential immune responses in pigs with PRRS or PRDC.

• Korean Journal of Veterinary Research
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• v.37 no.2
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• pp.417-423
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• 1997

돼지 생식기 호흡기 증후군 바이러스의 nucleocapsid와 반응을 하는 SDOW17 단크론항체를 이용하여 중성 포르말린에 고정시킨 자연감염된 포유자돈의 폐장에서 면역조직화학법을 이용하여 돼지 생식기 호흡기 증후군 바이러스 항원을 확인하였다. 서울대학교 수의과대학 병리학교실에 의뢰된 포유자돈들 중에서 병리조직학적으로 폐장에서 간질성 폐렴이 관찰된 포유자돈 7두를 임의로 선택하여 본 실험을 실시하였다. 간질성 폐렴의 병변으로 많은 수의 대식세포 침윤을 동반한 폐포벽 두께의 증가와 제II형 폐포세포의 비후가 관찰되었다. 검사한 7두 포유자돈중에서 6두에서 돼지 생식기 호흡기 증후군 바이러스에 대한 항체를 enzyme-linked immunosorbent assay에 의해 확인하였다. SDOW17 단크론항체를 이용한 면역조직화학염색과 간질성 폐렴의 대식세포에서 돼지 생식기 호흡기 증후군 바이러스의 항원을 검출하였고, 항원은 (주로)대식세포의 세포질에서만 진한 갈색의 양성반응이 관찰되었다. 이상 검사결과 돼지 생식기 호흡기 증후군 바이러스는 폐장의 간질과 폐포강에 분포되어 있는 대식세포에서 주로 증식하는 것으로 판명되었다. 본 실험에서 사용한 면역조직화학법은 돼지 생식기 호흡기 증후군 바이러스 감염여부를 바이러스 분리 또는 혈청검사 없이 진단하는데 사용할 수 있는 유용한 진단방법으로 판명되었다.

• Korean Journal of Veterinary Research
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• v.39 no.2
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• pp.318-326
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• 1999

Respiratory pathogenic effects of several porcine reproductive and respiratory syndrome virus(PRRSV) isolates were examined in swine tracheal ring(STR) cultures by examining their effect on ciliary activity. One high and one low pathogenic PRRSV isolates were then selected and their pathogenicity investigated in 3-week-old conventional PRRSV-seronegative pigs. Ten pigs each were inoculated intranasally with the high or low pathogenic PRRSV isolate and 6 pigs were sham inoculated as negative controls. Two pigs each from the inoculated group and one pig each from negative control group were killed on 4, 7, 14, 21 and 28 days postinoculation(pI). At necropsy, degrees of gross lung lesion was determined. Turbinate, tonsil, trachea and lung samples were collected for virus isolation or histopathology. Gross lung lesions were observed mainly on 14 days PI with high and low pathogenic isolates inducing moderate diffuse and mild gross lung lesions, respectively. Inoculation of either the high or low pathogenic virus resulted in loss of cilia in ciliated epithelium of turbinates and trachea between 7 and 28 days PI. High pathogenic virus caused increased number of Goblet cells in the tracheal epithelial layer between 4 and 21 days PI whereas the low pathogenic virus did it between 14 and 28 days PI and with a lesser degree. Although both viruses produced interstitial pneumonia, the lesion was less severe with the low pathogenic virus. The isolation of high pathogenic virus from tissues and sera was earlier and more consistent than that of the low pathogenic virus. The agreement between in vitro and in vivo tests indicates that STR cultures may be used as a routine method to determine the respiratory pathogenicity of PRRSV isolates.