• Korean Journal of Veterinary Research
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• v.58 no.1
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• pp.9-16
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• 2018

A preliminary study into the protective mechanisms of adaptive immunity against porcine reproductive and respiratory syndrome virus (PRRSV) in piglets (n = 9) born to a gilt challenged intranasally with a type-2 PRRSV. Immune parameters (neutralizing antibodies, $CD3^+CD4^+$, $CD3^+CD8^+$, $CD3^+CD4^+CD8^+$ T-lymphocytes, and PRRSV-specific interferon $(IFN)-{\gamma}$ secreting T-lymphocytes) were compared with infection parameters (macro- and microscopic lung lesion, and PRRSV-infected porcine alveolar macrophages ($CD172{\alpha}^+PRRSV-N^+\;PAM$) as well as with plasma and lymphoid tissue viral loads. Percentages of three T-lymphocyte phenotypes in 14-days post-birth (dpb) peripheral blood mononuclear cell (PBMC) had significant negative correlations with percentages of $CD172{\alpha}^+PRRSV-N^+\;PAM$ (p < 0.05) as well as with macroscopic lung lesion (p < 0.01). Plasma and tissue viral loads had significant (p < 0.05) negative correlations with $CD3^+CD4^+CD8^+$ T-lymphocyte percentage in PBMC. Frequencies of $CD3^+CD8^+$ and $CD3^+CD4^+$ T-lymphocytes in 14-dpb PBMC had significant negative correlations with of lymph node (p = 0.04) and lung (p = 0.002) viral loads. $IFN-{\gamma}$-secreting T-lymphocytes frequency had a significant negative correlation with gross lung lesion severity (p = 0.002). However, neutralizing antibody titers had no significant negative correlation (p > 0.1) with infection parameters. The results indicate that T-lymphocytes contribute to controlling PRRSV replication in young piglets born after in-utero infection.

• Korean Journal of Veterinary Service
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• v.34 no.2
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• pp.133-138
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• 2011

The prevention of porcine respiratory disease complex (PRDC) is very important because of its high infection-rates in the swine farms and the economic impact in swne industry in Korea. To control the prevalence of PRDC, it is important to know about infection patterns of it. Therefore, this study aimed to investigate the infection patterns of PRDC in the northern area of Gyeongsangnam-do. To this end, the infection of porcine reproductive and respiratory syndrome virus (PRRSV), porcine circovirus type 2 (PCV2), Actinobacillus pleuropneumoniae (APP), Mycoplasma hyopneumoniae (MH), and Swine influenza virus (SIV) were examined using 120 pig lung tissues by PCR analysis. As a result, single pathogen positive specimens were 25.0% and the others (75.0%) were turned out to be PRDC with at least two pathogens. Among PRDCs, 50 specimens (41.7%) was infected with PRRSV, PCV2, MH and SIV. Ten specimens (8.3%) showed triple infections of PRRSV, PCV2 and MH. Double infected specimens for PRRSV and PCV2 were 10 (8.3%), and for PCV2 and APP were 20 (16.7%).

• Korean Journal of Veterinary Research
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• v.57 no.2
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• pp.143-146
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• 2017

Porcine ear necrosis syndrome is characterized by erosive and ulcerative lesions at the margin or tip of the pinna. Three growing pigs of different ages exhibited retarded growth accompanied by reddening and necrosis of ear prior to death. Gross examination showed reddening, swelling, black discoloration, scaling, and variable-sized yellowish materials and edema in ear cross section. Microscopically, thrombosis, abscess, ulceration, epidermal hyperplasia, and dermal pyogranulomatous inflammation with an intralesional bacterial colony were observed. Staphylococcus hyicus was isolated in all pigs' ears and porcine reproductive and respiratory syndrome virus was detected by PCR and immunohistochemistry.

• Korean Journal of Veterinary Service
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• v.45 no.1
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• pp.63-69
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• 2022

Proliferative and necrotizing pneumonia (PNP) is a form of interstitial pneumonia that occurs in post-weaning pigs. In this study, we investigated the presence of swine influenza virus (SIV), porcine reproductive and respiratory syndrome virus (PRRSV), porcine circovirus type 2 (PCV2) and Aujeszky's disease virus (ADV) in PNP lesions in Jeju pigs. Based on the histopathologic criteria for PNP, a total of 50 cases were selected in Jeju pigs between 2008 and 2010. Coupled with histopathological examinations, the presence of ADV and SIV by polymerase chain reaction (PCR) and reverse transcription PCR (RT-PCR) and PRRSV and PCV2 by immunohistochemical (IHC) methods were investigated. Based on the PCR and RT-PCR methods, ADV and SIV nucleic acids were not detected in all cases. According to IHC, PRRSV was detected in 38 of the 50 cases examined (76%) and PCV2 in 25 cases (50%). PRRSV or PCV2 were detected in 19 (38%) or 6 (12%) cases, respectively. Both PRRSV and PCV2 were identified in other 19 cases (38%). Antigens of PRRSV and PCV2 were commonly observed in the cytoplasm of macrophages and clusters of necrotic cells in alveolar cavities. The results of the present study demonstrate that PRRSV is predominantly associated with PNP in Jeju pigs. Co-infection with PRRSV and PCV2 may enhance the severity of PNP lesions in affected pigs.

• Korean Journal of Veterinary Service
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• v.24 no.2
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• pp.127-132
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• 2001

Porcine circoviruses(PCV) are the smallest nonenveloped DNA viruses containing a unique single-stranded circular genome. No recognized link was found between PCV infection of pig and disease. But the PCV consistently identified from postweaning multisystemic wasting syndrome(PMWS) and researches indicate that there are strong relationships between PCV and PMWS. Clinical signs were emaciation, dyspnea, high fever with normal appetite. Necropsy findings showed respiratory disease complex lesion and lymph node anomalities. An indirect-immunofluorescent antibody procedure was used to assay swine sera for the presence of PCV atibodies. Antibodies against PCV were found in an average of 20% of the samples tested. The PCV DNA was amplified from lymph nodes collected from pigs. PCV specific primers were successfully amplified PCV DNAs. Further studies are needed to determine the possible role this virus might have in disease.

• Microbiology and Biotechnology Letters
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• v.43 no.1
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• pp.1-8
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• 2015

In this study, a DNA-launched reverse genetics system was developed from a type 2 porcine reproductive and respiratory syndrome virus (PRRSV) strain, KNU-12. The complete genome of 15,412 nucleotides was assembled as a single cDNA clone and placed under the eukaryotic CMV promoter. Upon transfection of BHK-tailless pCD163 cells with a full-length cDNA clone, viable and infectious type 2 progeny PRRSV were rescued. The reconstituted virus was found to maintain growth properties similar to those of the parental virus in porcine alveolar macrophage (PAM) cells. With the availability of this type 2 PRRSV infectious clone, we first explored the biological relevance of ORF5a in the PRRSV replication cycle. Therefore, we used a PRRSV reverse genetics system to generate an ORF5a knockout mutant clone by changing the ORF5a translation start codon and introducing a stop codon at the 7^th codon of ORF5a. The ORF5a knockout mutant was found to exhibit a lack of infectivity in both BHK-tailless pCD163 and PAM-pCD163 cells, suggesting that inactivation of ORF5a expression is lethal for infectious virus production. In order to restore the ORF5a gene-deleted PRRSV, complementing cell lines were established to stably express the ORF5a protein of PRRSV. ORF5a-expressing cells were capable of supporting the production of the replicationdefective virus, indicating complementation of the impaired ORF5a gene function of PRRSV in trans.

• 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.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 Research
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• v.37 no.1
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• pp.177-183
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• 1997

One cytopathogenic virus was isolated in alveolar macrophages from pig without any apparent respiratory clinical signs. Biophysical properties and electron microscopy of the isolate showed the characteristics of adenovirus. Intracytoplasmic inclusion bodies were seen in virus-inoculated cells. The genetic analysis indicated the presence of DNA with the size of >20Kb. In a serological survey of 40 serum samples collected from two different farms in slaughter house, 9 sera were positive for neutralizing antibody against the isolate. The potential implications of the isolate as the causative agent in respiratory disorder were discussed.

• Journal of Veterinary Science
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• v.21 no.6
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• pp.85.1-85.6
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• 2020

A cold-adapted porcine reproductive and respiratory syndrome virus (CA-VR2332) was generated from the modified live virus strain VR2332. CA-VR2332 showed impaired growth when cultured at 37℃ with numerous mutations (^S731^F, ^E819^D, ^G975^E, and ^D1014^N) in the hypervariable region of the NSP2, in which the mutation ^S731^F might play a vital role in viral replication at 30℃. Conserved amino acid sequences of the GP5 protein suggests that CA-VR2332 is a promising candidate for producing an effective vaccine against PRRSV infection. Further studies on replication and immunogenicity in vivo are required to evaluate the properties of CA-VR2332.