• Korean Journal of Veterinary Service
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• v.38 no.2
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• pp.89-94
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• 2015

Respiratory disease in pigs is common in modern pork production worldwide and is often referred to as porcine respiratory disease complex (PRDC). PRDC is polymicrobial in nature, and results from infection with various combinations of primary and secondary respiratory pathogens. The control of swine respiratory disease requires an understanding of the interactions between the organisms that can cause this illness, the pig and management of the environment. This study was carried out to investigate the lesion of red internal organs in slaughtered pigs and provided assistant data for pig farms. A total of 900 lung samples, 45 farms were collected randomly from slaughtered pigs in Jeonbuk province from April to December in 2014. Gross lesions such as swine enzootic pneumonia (SEP), pleuritis, pleuropneumonia, pericarditis, liver white spots were examined for the pigs. Overall prevalence of SEP was 70.8%. According to season, the incidence occurred higher in summer than winter, fall and spring. The mean SEP score was 1.4, the highest incidence occurred in fall. The prevalence of pleuropneumonia, pleuritis, pericarditis, and milk spot was 26.1%, 71.4%, 2.8%, 21.6%, respectively. In the detection of pathogens, PRRS was not detected, PCV2 was positive in 87.6%.

• Journal of Veterinary Clinics
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• v.22 no.4
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• pp.365-370
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• 2005

Enzootic pneumonia caused by Mycoplasma hyopneumoniae is responsible for major economic losses in pig herds of world wide. Mycoplasma hyopneumoniae can also act as a primary pathogen of porcine respiratory disease complex followed by bacterial or viral infection. This study was carried out to investigate the prevalence of mycoplasmal pneumonia of slaughtered pigs in Jeju for two years. The lungs and sera of 214 cases were examined for gross and microscopic lesions of the lungs, immunohistichemistry test for Mycoplasma hyopneumoniae antigen and enzyme-linked immunohistichemistry assay (ELISA) for serum antibody titer. Pulmonary consolidation was observed in the lungs of 163 pigs $(76.1\%)$ with average gross lesion score of $6.0\%$., Bronchointerstitial pneumonia was most frequently observed $(78.5\%)$. The incidence of pulmonary consolidation was decreased in vaccinated pigs compared to that of non-vaccinated pigs. The rate of consolidation in the lungs was significantly decreased in the vaccinated pigs (P<0.05). Antigen of Mycoplasma hyopneumoniae was identified by immunohistichemistry test in the lungs of 174 pigs $(81.3\%)$. ELISh antibodies to Mycoplasma hyopneumoniae were detected in 154 pigs $(72.0\%)$. These results showed the prevalence of swine pneumonia and the incidence of Mycoplasma hyopneumoniae in slaughtered pigs of Jeiu province. We expect that these results would be helpful for the control of swine mycoplasmal pneumonia and porcine respiratory disease complex in Jeju.

• Korean Journal of Veterinary Service
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• v.34 no.4
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• pp.389-395
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• 2011

The aims of this study were to assess the lung lesions and to compare gross observations with histopathological findings in the lungs of slaughter pigs. During August of 2010 through July of 2011, the 1,200 lung samples were randomly collected from slaughtered pigs in Korea. We examined prevalence of lung lesions and classified the lung lesion according to the severity of lung lesions. For the comparison of gross lesions with histopathological findings, BALT hyperplasia was also examined. Among the tested samples, 1,100 (91.7%) had pneumonic lung lesions. In the seasonal prevalence of pneumonic lung lesions, spring was the highest followed by winter, summer and autumn, respectively. The mean pneumonic score ($mean{\pm}SD$) was $21.37{\pm}17.87$ and the highest gross lesion according to stages was 11~20% (27.2%, 326/1,200). The prevalence of pleuritis was 7.0% and the highest prevalence was determined in summer. In severity, the lungs collected in this study were frequently in chronic stage (36.4%, 437/1,200), and it was shown that BALT hyperplasia was more extensive in chronic lesion. In this study, the prevalence of pneumonic lung lesions showed a high side and appeared particularly high in the spring. Severity of lung lesion was the most prevalent chronic lesions which were consistent with histopathologic findings.

• Journal of Veterinary Science
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• v.22 no.3
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• pp.39.18-39.18
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• 2021

Background: Interferon lambda receptor 1 (IFNLR1) is a type II cytokine receptor that clings to interleukins IL-28A, IL29B, and IL-29 referred to as type III IFNs (IFN-λs). IFN-λs act through the JAK-STAT signaling pathway to exert antiviral effects related to preventing and curing an infection. Although the immune function of IFN-λs in virus invasion has been described, the molecular mechanism of IFNLR1 in that process is unclear. Objectives: The purpose of this study was to elucidate the role of IFNLR1 in the pathogenesis and treatment of porcine reproductive and respiratory syndrome virus (PRRSV). Methods: The effects of IFNLR1 on the proliferation of porcine alveolar macrophages (PAMs) during PRRSV infection were investigated using interference and overexpression methods. Results: In this study, the expressions of the IFNLR1 gene in the liver, large intestine, small intestine, kidney, and lung tissues of Dapulian pigs were significantly higher than those in Landrace pigs. It was determined that porcine IFNLR1 overexpression suppresses PRRSV replication. The qRT-PCR results revealed that overexpression of IFNLR1 upregulated antiviral and IFN-stimulated genes. IFNLR1 overexpression inhibits the proliferation of PAMs and upregulation of p-STAT1. By contrast, knockdown of IFNLR1 expression promotes PAMs proliferation. The G0/G1 phase proportion in IFNLR1-overexpressing cells increased, and the opposite change was observed in IFNLR1-underexpressing cells. After inhibition of the JAK/STAT signaling pathway, the G2/M phase proportion in the IFNLR1-overexpressing cells showed a significant increasing trend. In conclusion, overexpression of IFNLR1 induces activation of the JAK/STAT pathway, thereby inhibiting the proliferation of PAMs infected with PRRSV. Conclusion: Expression of the IFNLR1 gene has an important regulatory role in PRRSV-infected PAMs, indicating it has potential as a molecular target in developing a new strategy for the treatment of PRRSV.

• 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 The Korean Society of Agricultural Engineers
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• v.56 no.1
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• pp.41-49
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• 2014

Pig chronic wasting disease, including porcine reproductive and respiratory syndrome (PRRS) and postweaning multisystemic wasting syndrome (PMWS), have made a continuous economic damage in pig farms. Airborne spread of livestock viruses are an important spread factor which is difficult to analyze due to invisible airflow and limitation of measurement. The objective of this study is to analyze airborne disease spread between buildings in the experimental pig farm by means of field experiment and computational fluid dynamics (CFD). The field experiments were conducted to capture airborne virus using air sampler and teflon filter along multi points in the experimental pig farm. The samples were tested in terms of virus detection resulting in positive reaction for PRRS and PCV-2 viruses, which can be a firm evidence of airborne virus spread. The CFD simulation model was developed by considering complex topography, wind conditions, building arrangement, and ventilation systems and was used to analyze airborne virus spread according to different wind conditions. The CFD computed result showed a possibility of airborne virus spread via livestock aerosol from infected pig house to neighboring pig houses according to wind directions. The CFD simulation technique is expected to provide significant data for estimating and making a counterplan against airborne disease spread.

• Korean Journal of Veterinary Research
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• v.40 no.1
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• pp.173-186
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• 2000

This experiment was carried out to investigate the tendency of incident diseases in pre- and post- weaning piglets which ages were 1 to 7 weeks old by laboratory diagnosis and in order to minimize death in preweaning piglets and of stunted growth in postweaning piglets. The result of this experiment used as the basic data for the preventive programs in pre- and post- weaning piglets and were as follows: 23 different diseases diagnosed in 331 cases were studied in relation to age, season, and etiology. The most prevelent diseases of pre- and post- weaning piglet were Colibacillosis(79 case, 23.9%) and the major diseases were Salmonellosis(44 cases, 13.3%), Anemia(37 cases, 11.2%). Unknown viral disease(20 case, 6.1%), Rota viral infection(19 case, 5.8%), Porcine reproductive & respiratory syndrome(PRRS; 15 case 4.5%), Transmissible gastroenteritis(TGE; 12 case, 3.6%). The gastrointestinal disease, such as Colibacillosis, Salmonellosis, Swine dysentery, Clostridial infection, Rotaviral infection, TGE, Porcine epidemic diarrhea(PED) and Ballantidiosis occured pro- dominently in the period of pre- and post- weaning, which were 178 cases(53.8%) and not related to occurrence according to age and season. The respiratory diseases were Atrophic rhinitis(AR), Swine enzootic pneumonia, Pneumonic pasteurellosis, Pleuropneumonia, Branchopneumonia, PRRS and which were 48 cases(14.5%) and higher prevalent in spring and summer. The viral diseases was 73 cases(22.1%) that occurred in the period of 5 weeks piglet and prevalent mainly in spring. The bacterial diseases were 188 cases(56.8%) that were not related to occurrence according to age and season. Salmonellosis was prevalent in 3 to 5 weeks piglet and mainly occurred in summer. Viral septicemia and rotaviral infection occurred after 5 weeks piglets intensively and 3 to 5 weeks, respectively. And the both occurred without relation with season. PRRS occurred after 4 weeks piglet and prevalent in summer. TGE occurred 1 to 7 days old piglets and prevalent in spring and winter. Hematologic values of anemia was decrease in number of Red Blood Cell, concentration of Hemoglobin and Hematocrit. Amikacin, cephalothin, colistin, norfloxacin were effective to E coli, and amikacin, cephalothin, nortloxacin, neomycin were effective to Salmonellra spp. but clindamycin, erythromycin, penicillin, sulfonamides were resistant to E coli and Salmonella spp.

• Korean Journal of Veterinary Research
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• v.48 no.1
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• pp.67-73
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• 2008

Porcine reproductive and respiratory syndrome (PRRS) is the most economically important viral infectious disease in pig populations worldwide. This study was conducted to better understand the epidemic and dynamics of PRRS virus (PRRSV) on each farm and to evaluate the risk of PRRSV infection in Korea. Interviews with pig farmers were carried out to obtain PRRS vaccination programmes in 60 pig farms throughout Korea. Blood samples were also collected from the 59 pig farms to investigate outbreak patterns of each farm. Vaccination against PRRS was performed in 16.7% farms for breeding pigs and 8.3% of farms for nursery pigs. According to the seroepidemiological analysis, 56 (94.9%) out of 59 farms were considered to be affected by PRRSV infection. The results revealed that 68.9% of sows tested were seroconverted and interestingly, gilt herds had the highest seropositive rate (73%), suggesting that gilts may play a key role in PRRSV transmission in sow herds. Among the PRRS-affected piglet herds, 33 (55.9%), 14 (23.7%) and 6 (10.2%) farms were initially infected with PRRSV during the weaning, suckling and nursery period, respectively. It seems likely, therefore, that PRRSV infection predominantly occurs around the weaning period in piglet herds. Based on antibody seroprevalence levels in both sow and piglet groups, we were able to classify patterns of PRRSV infection per farm unit into 4 categories; category 1 (stable sow groups and non-infected piglet groups), category 2 (unstable sow groups and non-infected piglet groups), category 3 (stable sow groups and infected piglet groups), and category 4 (unstable sow groups and infected piglet groups). Our data suggested that 43 (72.9%) farms were analysed to belong to category 4, which is considered to be at high-risk for PRRS outbreak. Taken together, our information from this study will provide insight into the establishment of an effective control strategy for PRRS on the field.

• Journal of Veterinary Science
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• v.24 no.5
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• pp.54.1-54.13
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• 2023

Background: Porcine reproductive and respiratory syndrome virus (PRRSV) vaccines do not provide full cross-protection, mainly due to the virus genetic variability. Despite this, vaccines based on modified-live PRRSV (PRRSV-MLV) reduce the disease impact. Objectives: To assess the efficacy of two commercial vaccines-one based on PRRSV1 (PRRSV1-MLV) and another on PRRSV2 (PRRSV2-MLV)-against a Japanese PRRSV2 field strain. Methods: Two groups of three-week-old piglets were vaccinated (G1: PRRSV1-MLV; G2: PRRSV2-MLV) and two were kept as non-vaccinated (INF and CTRL). One month later, G1, G2, and INF were challenged with a PRRSV2 field strain. Results: After the challenge, clinical signs were only observed in INF. Moreover, the highest rectal temperatures and values for the area under the curve (AUC) were observed in INF. Regarding viral detection, both AUC and the proportion of positive samples in blood were higher in INF. In G1, viremic animals never reached 100%. At necropsy (21 d after the challenge), differences for titers among groups were only found in tonsils (G1 < G2 and INF). One animal (belonging to G1) was negative in all tissues. Regarding humoral responses, G1 and G2 seroconverted after vaccination, as detected in the corresponding enzyme-linked immunosorbent assay. Specific neutralizing antibodies (NA) against PRRSV1-MLV were already detected at 14 d after vaccination in G1, showing a significant booster after the challenge, while PRRSV2-MLV NA were detected in G2 at the end of the experiment. Conclusions: Despite genetic differences, PRRSV1-MLV has been demonstrated to confer partial protection against a Japanese PRRSV2 strain, at least as good as PRRSV2-MLV.

• Korean Journal of Veterinary Service
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• v.34 no.2
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• pp.117-123
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• 2011

This experiment was conducted to investigate the presence of recognized abortifacient viruses from aborted fetuses and stillborn piglets in cases of reproductive failure in sows by PCR. A total of 219 samples of aborted fetuses or stillborn piglets, submitted to the School of Veterinary Medicine of Kangwon National University between 2006 and 2009 May, were collected from 5 provinces in Korea. Abortifacient virus infections were detected in 82 (37.4%) out of 219 aborted fetuses or stillborn piglets as well as on 39 (40.2%) out of 97 pig farms. The major viral infections were porcine circovirus type 2 (PCV2), porcine reproductive and respiratory syndrome virus (PRRSV) and Aujesky's disease virus (ADV) for which 46 (21%), 19 (8.6%) and 16 (7.3%) were positive, respectively, with 9 fetuses had complicated infection of PCV2+PRRSV or ADV or both. And 8 (3.6%) for SIV, 3 (1.3%) for PPV and 1 (0.4%) for JEV were positive as minor viral infection. The results suggest that PCV2, PRRSV, ADV is apparently the most important viral infectious agents associated with fetal infection leading to abortion or stillbirth in Korea. SIV, PPV and JEV might have a minor impact on reproductive disease.