• Korean Journal of Veterinary Research
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• v.44 no.4
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• pp.571-579
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• 2004

In order to obtain the genetic informations of the Korean isolates of porcine circovirus 2 (PCV2), nucleotide sequences of total genome of three isolates and open reading frame 2 (ORF2) of four isolates were determined and compared with those of other reference PCV2 isolates. Nucleotide sequences of 3 isolates showed over 99% homology with those of reference strain (GenBank accession no. AF027217). Point mutations were mainly determined on ORF2 regions but little on ORF1 regions. The patterns of pointmutated sites and nucleotide substitution on ORF2 regions were generally consistent between Korean isolates, and these mutated sites observed in Korean isolates were also relatively similar to those of foreign isolates. Phylogenetic analysis of nucleotide or amino acid sequences showed that there were minor branches consisting of three clusters; cluster of Korea, Canada and America, cluster of Spain and Taiwan, and the last cluster of French and China isolates. These results suggested that Korean PCV2s were probably originated from North America such as Canada or USA. The genetic informations obtained from this study could be useful for the research of diagnosis and pathogenecity of PCV2.

• Korean Journal of Veterinary Research
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• v.44 no.4
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• pp.561-569
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• 2004

To detect viral agents and isolate porcine circovirus 2 (PCV2), 60 samples of lung and lymph node were collected from 5 to 12 week-old pigs that had showed clinical signs of postweaning multisystemic wasting syndrome (PMWS). Polymerase chain reactions (PCRs) were conducted to identify the viral pathogens including PCV1, PCV2, porcine parvovirus (PPV) and porcine reproductive and respiratory syndrome virus (PRRSV) that have been considered to be the causal agents of PMWS. Among 60 samples, PCV 2 was detected from 57 samples but no PCV 1 was detected. PRRSV and/or PPV were also detected from 27 (47.4%) samples and 1 (1.8%) sample of these 57 PCV 2-positive samples, respectively. Tissue homogenates were inoculated onto PCV-free PK-15 cell monolayers. Seven isolates were confirmed as PCV 2 by multiplex PCR, indirect immunofluorescence assay, and transmissible electron microscopy. These date suggest that PRRSV is a major cofactors causing PMWS in pigs that were infected with PCV2 in Korea.

• Korean Journal of Veterinary Research
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• v.58 no.3
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• pp.143-146
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• 2018

The capsid protein of porcine circovirus type 2 (PCV2) encoded by open reading frame 2 (ORF2) is important for neutralizing activity against PCV2 infection. This study investigated the heterogeneity of the ORF2 gene of PCV2 isolated in Korea during 2016-2017. The results revealed that PCV2d is currently the predominant genotype. Moreover, comparison of ORF2 from 17 PCV2 isolates revealed 88.3-100% homology at the nucleotide (deduced amino acid 86.3-100%) level. Interestingly, 61.5% (8/13) of the PCV2d isolates had glycine at position 210. These data provide a useful information for PCV2 epidemiology in Korea.

• Korean Journal of Veterinary Service
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• v.39 no.1
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• pp.59-63
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• 2016

Duck circovirus (DuCV) has been recognized as a contagious immunosuppressive virus affecting many duck species worldwide. To determine the prevalence of DuCV infection in ducks, we investigated 104 samples collected from 50 duck farms in Jeonbuk province with the polymerase chain reaction (PCR). Among collected samples, 40 (38.5%) were positive for DuCV. The prevalence of DuCV PCR-positive samples increased with age. Genomic sequences of 15 DuCV strains were determined and compared with previously available DuCV sequences in public databases. Phylogenetic analysis revealed that all strains were clustered into DuCV-1 group.

• Korean Journal of Veterinary Research
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• v.43 no.3
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• pp.463-469
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• 2003

Eight nursery to grower pigs exhibiting weight loss and sudden death were diagnosed as postweaning multisystemic wasting syndrome (PMWS) based on the results of gross findings, histopathology, immunohistochemistry, fluorescent antibody test, virus isolation, PCR, serology, and electron microscopy. Groosly, the pigs had a rough hair coats and were severely emaciated. And moot lymph nodes were pale and enlarged. Lungs were not fully collapsed and exhibited 10 to 40% pale red cranioventral consolidation. Histopathologically, typical lymphohistiocytic interstitial to bronchointerstitial pneumonia, chronic lymphadenitis, severe lymphoid depletion, and basophilic intracytoplasmic inclusions were noted in the most lymphoid tissues. Porcine circovirus panicles were observed in the inguinal lymph node of the pigs by electron microscopy. Porcine circovirus type 2 (PCV2) antigens or viral DNAs were detected in the lesions of all pigs using immunohistochemistry or PCR. Two PCV2 were isolated from a homogenate of pooled lung and lymph node in 2 of the 5 pigs. Additionally, antigens of porcine reproductive and respiratory syndrome virus (PRRSV) and Hemophilus (H.) parasuis were also detected by immunofluorescent antibody test. Serologically, 55% of randomly selected sows and fattening pigs was serum antibody positive to PCV2 by an indirect fluorescent antibody (IFA) test and approximately 18 % of animals in the herd were serologically pooitive by the ELISA kit for PRRSV. To our knowledge, this is the first report of PMWS co-infected with PCV-2, PRRS, and H. parasuis in Korea.

• Journal of Veterinary Science
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• v.22 no.1
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• pp.8.1-8.11
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• 2021

Background: Porcine circovirus type 2 (PCV2) is an important infectious pathogen implicated in porcine circovirus-associated diseases (PCVAD), which has caused significant economic losses in the pig industry worldwide. Objectives: A suitable viral vector-mediated gene transfer platform for the expression of the capsid protein (Cap) is an attractive strategy. Methods: In the present study, a recombinant adeno-associated virus 8 (rAAV8) vector was constructed to encode Cap (Cap-rAAV) in vitro and in vivo after gene transfer. Results: The obtained results showed that Cap could be expressed in HEK293T cells and BABL/c mice. The results of lymphocytes proliferative, as well as immunoglobulin G (IgG) 2a and interferon-γ showed strong cellular immune responses induced by Cap-rAAV. The enzyme-linked immunosorbent assay titers obtained and the IgG1 and interleukin-4 levels showed that humoral immune responses were also induced by Cap-rAAV. Altogether, these results demonstrated that the rAAV8 vaccine Cap-rAAV can induce strong cellular and humoral immune responses, indicating a potential rAAV8 vaccine against PCV2. Conclusions: The injection of rAAV8 encoding PCV2 Cap genes into muscle tissue can ensure long-term, continuous, and systemic expression.

• Journal of Veterinary Science
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• v.23 no.3
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• pp.49.1-49.13
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• 2022

Background: Porcine circovirus type 2 (PCV2) and Mycoplasma hyopneumoniae (MHP) are economically significant pathogens in the pig industry. The use of combined vaccines against PCV2 and MHP is one of the most effective ways of protecting pigs from both diseases, and it has become a part of general management. Objectives: This study evaluated the efficacy of two new bivalent vaccines of PCV2 and MHP (Myco-X and Myco-XD) in SPF pigs. Myco-X and Myco-XD are a combined vaccine of MHP with PCV2b and PCV2d, respectively. Methods: Sixteen pigs were divided into four groups: Myco-X-vaccinated challenged, Myco-XD-vaccinated challenged, unvaccinated challenged, and unvaccinated unchallenged. Two milliliters of Myco-X were administered intramuscularly, and 0.5 mL of Myco-XD was injected intradermally at 3 wk of age. The pigs were challenged with virulent PCV2d via the intramuscular and intranasal route 4 wk post-vaccination. Results: All vaccinated pigs showed effective reduction of the clinical signs, the PCV2d load in the blood and nasal swab samples, as well as lung and lymphoid tissue lesions in the challenge test. Compared to unvaccinated challenged animals, the vaccinated challenged animals showed significantly higher (p < 0.05) levels of anti-PCV2 IgG, PCV2d-specific interferon-γ (IFN-γ), and anti-MHP IgG. Conclusions: Based on clinical, microbiological, serological, and pathological assessments, this study confirmed that both combined vaccines could protect pigs against PCV2 infection caused by PCV2d. On the other hand, further research on the efficacy evaluation of these new vaccines against the MHP challenge and PCV2d/MHP co-challenge is needed.

• Journal of Veterinary Science
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• v.25 no.2
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• pp.28.1-28.11
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• 2024

Background: Porcine circovirus type 2 (PCV2) infection is ubiquitous around the world. Diagnosis of the porcine circovirus-associated disease requires clinic-pathological elements together with the quantification of viral loads. Furthermore, given pig farms in regions lacking access to sufficient laboratory equipment, developing diagnostic devices with high accuracy, accessibility, and affordability is a necessity. Objectives: This study aims to investigate two newly developed diagnostic tools that may satisfy these criteria. Methods: We collected 250 specimens, including 170 PCV2-positive and 80 PCV2-negative samples. The standard diagnosis and cycle threshold (Ct) values were determined by quantitative polymerase chain reaction (qPCR). Then, two point-of-care (POC) diagnostic platforms, convective polymerase chain reaction (cPCR, qualitative assay: positive or negative results are shown) and EZtargex (quantitative assay: Ct values are shown), were examined and analyzed. Results: The sensitivity and specificity of cPCR were 88.23% and 100%, respectively; the sensitivity and specificity of EZtargex were 87.65% and 100%, respectively. These assays also showed excellent concordance compared with the qPCR assay (κ = 0.828 for cPCR and κ = 0.820 for EZtargex). The statistical analysis showed a great diagnostic power of the EZtargex assay to discriminate between samples with different levels of positivity. Conclusions: The two point-of-care diagnostic platforms are accurate, rapid, convenient and require little training for PCV2 diagnosis. These POC platforms can discriminate viral loads to predict the clinical status of the animals. The current study provided evidence that these diagnostics were applicable with high sensitivity and specificity in the diagnosis of PCV2 infection in the field.

• Korean Journal of Veterinary Service
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• v.29 no.1
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• pp.1-8
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• 2006

Porcine circovirus (PCV) is a small, nonenveloped virus that contains a single-stranded circular DNA genome of about 1.76 kb and belongs to the family circoviridae. The PCV-2 has been incriminated as the cause of post-weaning multisystemic wasting syndrome (PMWS) , an emerging disease in pigs. In the present study, a PCR assay was applied to detect PCV-2 in tissue samples. The presence of PCV-2 antigen in the porcine tissues was confirmed by indirect immunofluorescence (IIF) with PCV-2 specific monoclonal antibodies. And then DNA extracted from PCV-2 positive tissues was used as a template. One oligonucleotide primer suitable for PCR was selected from a published PCV-2 sequence (Genbank). Amplified PCR product was detected the same fragment lengths of 416 bp as a control. Based on these results, it was suggested that the PCR is a simple and sensitive method for support diagnostic purposes.

• Korean Journal of Veterinary Service
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• v.34 no.1
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• pp.1-4
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• 2011

A surface plasmon resonance imaging (SPRI) assay was developed for measuring porcine circovirus type 2 (PCV2) antibody using a recombinant capsid protein as an antigen. The diagnostic potential of SPRI for detecting antibodies to the PCV2 capsid protein was compared with that of a conventional enzyme-linked immunosorbent assay (ELISA) using 70 pig serum samples taken from 6 pig farms. There was a strong positive correlation between the SPRI and ELISA (n = 70, r = 0.911, P<0.01). Therefore, this recombinant capsid protein can be used as an antigen for serological studies, and the SPRI, a label-free and high-throughput method, is expected to be a valuable tool in the serodiagnosis of PCV2 infection.