• 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.41 no.3
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• pp.133-139
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• 2018

Porcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV) are known as significant immunosuppressive viruses in pigs. In this study, we investigated the correlation of PCV2 and PRRSV in enteric lesions of porcine salmonellosis. A total of 64 cases were classified into four pig groups as group A (24 cases, S. Typhimurium), group B (11 cases, S. Typhimurium+PCV2), group C (16 cases, S. Typhimurium+PRRSV) and group D (13 cases, S. Typhimurium+PCV2+PRRSV). Comparing with group A, ulcerative enteritis in large intestine was little more prevalent in the PCV2 infected pigs in group B and D. And lymphoid depletion in gut-associated lymphatic tissue (GALT) of large intestine was also detected in PCV2 positive group B (36.4%) and D (30.8%). According to the results of immunohistochemistry (IHC), PCV2 antigens (83.3%) were more prevalently distributed in the intestinal lesions of porcine salmonellosis than PRRSV antigens (10.3%). PCV2 were also detected in the lymphoid depleted GALT of the large intestine from 7 of the 8 pigs (87.5%), but PRRSV were not found in all cases. It may explain that PCV2 can play a certain immunological role to enhance secondary bacterial infection in porcine alimentary tracts.

• Korean Journal of Veterinary Research
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• v.53 no.4
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• pp.245-251
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• 2013

Porcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV) have been suspected to have immunosuppressive effects on pigs. To investigate the correlation between these virus infection and the lesions of lymph nodes including sub-mandibular and inguinal lymph node, 44 pigs (PCV2 single, n = 14; PRRSV single, n = 10; PCV2/PRRSV, n = 14; negative control, n = 6) were examined by histopathology and immunohistochemistry. Histopathologically, granulomatous lymphadenitis characterized by lymphoid depletion with histiocytic cells infiltration was observed in PCV-2 single and PCV-2/PRRSV group. Immunohistochemically, there were significant reduction of B and T lymphocytes in lymph nodes of these groups, while the number of macrophages was increased. In only PRRSV infected group, germinal center hypertrophy and lymphoid necrosis were observed. Immunohistochemically, the number of CD3+ T lymphocytes was slightly increased. Severe lymphocytic depletion in PCV-2 infection-related lymph nodes might be associated with producing immunocompromised state in pig. Comparing with PCV-2 infected group, PRRSV produced minor effects on the changes in immune cell population in the lymph nodes of pigs. PRRSV may increase susceptibility of the disease in pigs by disruption of the first defense lines in target organs, such as the alveolar macrophages in lungs.

• 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.

• Korean Journal of Veterinary Research
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• v.60 no.3
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• pp.155-161
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• 2020

From 2006 to 2009, 50 pigs suspected of enteritis associated with porcine circovirus type 2 (PCV-2) (EAPC) were collected. Gross and histopathologic examinations and immunohistochemistry (IHC) were performed on the small intestine of 50 pigs. The pigs with EAPC were concentrated in grower pigs (68%), and diarrhea (84%) was the most common clinical sign. Grossly, the walls of the small intestine were thickened, and mesenteric lymph nodes were enlarged. The histopathologic features in the small intestine with EAPC were characterized by lymphoid depletion, histiocytic infiltration, and formation of basophilic grape-like inclusion bodies and multinucleated giant cells in gut-associated lymphatic tissue (GALT) and lamina propria. According to IHC, PCV-2 antigens were more intense and distributed widely in GALT (98%) than lamina propria (82%) of the small intestine. Co-infection with other enteric pathogens was detected in 26 pigs (52%). Twenty-four pigs (48%) were confirmed to be a PCV-2 single infection. Collectively, infected PCV-2 in the small intestine may induce an immunosuppressive status of individuals and then allow secondary co-infections in the digestive system. This study shows that PCV-2 can induce diarrhea and enteric lesions in pigs without a co-infection of other enteric pathogens.

• Journal of Preventive Veterinary Medicine
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• v.41 no.3
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• pp.129-132
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• 2017

The current study identified risk factors associated with porcine circovirus type 2 (PCV2) infection on pig farms in the Republic of Korea using a multinomial logistic regression model to evaluate the PCV2 infection status of pigs at different growth stages. Compulsory disinfection of visitors (odds ratio [OR]: 0.019, 95% confidence interval [CI]: <0.001-0.378, p=0.0095), compulsory registration of visitors (OR: 0.002, 95% CI: <0.001-0.184, p=0.0070), regular blood testing (OR: 0.012, 95% CI: <0.001-0.157, p=0.0007), and running on-farm biosecurity learning programs for workers (OR: 0.156, 95% CI: 0.040-0.604, p=0.0072 and OR: 0.201, 95% CI: 0.055-0.737, p=0.0155, respectively) were identified as factors which could reduce the risk of PCV2 infection. However, visitation by a regular veterinarian (OR: 32.733, 95% CI: 3.768-284.327, p=0.0016) was associated with PCV2 infection.

• Journal of Veterinary Clinics
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• v.27 no.6
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• pp.704-712
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• 2010

Porcine circovirus-2 (PCV2) has been implicated in many clinical diseases/syndromes that are now referred to as PCV-associated diseases (PCVAD). Due to significant economic losses caused by PCVAD, many swine operations have launched extensive monitoring programs for PCV2. Traditional serum sampling is, however, rather expensive and laborious, hampering effective large scale pathogen surveillance. A field-based longitudinal study was conducted to assess the utility of pen-based oral fluid sample as an alternative to serum for herd PCV2 testing. Six pens (25 pigs/pen) at each of 3 different sites were used in the study. One oral fluid and 5 random serum samples per pen were collected at 3, 5, 8, 12, and 16 weeks of age, and the sera were pooled by pen for testing. All samples were tested for PCV2 by real-time PCR and for antibodies by indirect fluorescent antibody test (for both anti-PCV2 IgG and IgA) and 3 ELISA assays (blocking ELISA, indirect ELISA, and IgG/IgM sandwich ELISA). PCV2 DNA was detected in oral fluid samples sporadically until 8 weeks and in all pens at 16 weeks. PCV2-specific IgG was detected in oral fluid samples at 3 weeks and persisted until 5 to 8 weeks in all sites. Anti-PCV2 IgG and IgA were detectable in oral fluid samples collected at 16 weeks from all of the pens at 1 site. The detection of PCV2 and anti-PCV2 antibody in oral fluid samples correlated positively with results on pooled sera, suggesting that oral fluids can be a cost-effective alternative to serum for herd monitoring of PCV2 infection.

• Journal of Animal Science and Technology
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• v.63 no.6
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• pp.1223-1231
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• 2021

Regulator of G protein signaling 16 (RGS16) is known to be associated with porcine circovirus type 2 (PCV2). PCV2 associated disease (PCVAD) is a serious problem in the swine industry. The representative symptoms of PCVAD are high viral titer proliferation and decreased average daily gain. In this study, we identified single nucleotide polymorphisms (SNPs) in the RGS16 region, including the upstream region. Of the 22 identified SNPs, rs332913874, rs326071195, and rs318298586 were genotyped in 142 Yorkshire pigs. These SNPs were significantly associated with the PCV2 viral load. Moreover, the haplotype combination was also related to the PCV2 viral load. The haplotype and diplotype analysis also had a significant difference with the PCV2 viral load. Taken together, our results suggest that RGS16 SNPs considerably affect the PCV2 viral load.

• International Journal of Industrial Entomology and Biomaterials
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• v.30 no.2
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• pp.50-57
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• 2015

Porcine circovirus type 2 (PCV2) is an important infectious swine virus causing postweaning multisystemic wasting syndrome (PMWS). PCV2 capsid protein, encoded by ORF2 has type-specific epitopes, is very immunogenic, and is associated with the induction of neutralizing antibodies. For the efficient production of capsid protein, recombinant Autographa californica nucleopolyhedroviruses were generated to express ORF2 fused with two forms of a partial polyhedrin. Recombinant capsid protein was produced successfully with the partial polyhedrin fusion form and the yield was high, as was shown by SDS-PAGE. Production of recombinant capsid proteins in insect cells was confirmed by Western blot analysis using anti-His monoclonal antibody, anti-ORF2 monoclonal antibody, and anti-PCV2 porcine serum. Fusion expression with amino acids 19 to 110 of the polyhedrin increased the production of recombinant capsid protein, but fusion with amino acids 32 to 85 did not. Additionally, PCV2 capsid protein is a glycoprotein; however, the glycosylation of recombinant protein was not observed. The results of an Enzyme-linked immunosorbent assay (ELISA) showed that recombinant capsid proteins could be utilized as antigens for fast, large-scale diagnosis of PCV2-infected pigs. Our results suggest that the fusion expression of partial polyhedrin is able to increase the production of recombinant PCV2 capsid protein in insect cells.

• Korean Journal of Veterinary Service
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• v.29 no.3
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• pp.249-256
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• 2006

Porcine circovius type 2 (PCV 2) is a novel virus of Circoviridae familiy which is considering the cause of postweaning multisystemic wasting syndrome (PMWS). This study was carried out to investigate the prevalence of PCV 2 infection of swine in eastern areas of Gangwon province from February to June in 2005. Polymerase chain reaction (PCR) were conducted to identify the PCV 2 genome against 80 pigs. The number of infection and its rate of 4 areas, 8 farms and 80 pigs were 3 (75.0%), 7 (88.0%) and 44 (55.0%), respectively.