• 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.

• Korean Journal of Veterinary Service
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• v.42 no.1
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• pp.1-7
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• 2019

Porcine reproductive and respiratory syndrome (PRRS) is economically the most important and challenging disease in swine industries worldwide and caused by PRRS virus (PRRSV). Previous studies reported that pigs with heterozygous genotypes in the guanylate-binding proteins (GBP1 and GBP5) exhibited increased resistance against PRRSV infection. The present study was conducted to produce higher numbers of the heterozygous pigs based on the PRRS resistant polymorphisms found in GBP1 (GBP1E2 and WUR) and GBP5, and evaluate the resistance of heterozygous pigs against challenge with a type 2 PRRSV (JA142) in comparison with homozygous pigs. In the challenge study, 12, 4 week-old PRRSV-negative piglets were selected based on the genotypes of the 3 polymorphisms (GBP1E2, WUR and GBP5). Among them, 8 piglets [homozygous (n=4) and heterozygous (n=4)] were challenged with JA142 and kept in the same room, and the remaining 4 piglets were kept separately as a negative control. In results, the sperms collected from the boars of GBP1E2-GG genotype produced approximately 28~41% higher numbers of heterozygous piglets as compared with those from the boars of GBP1E2-AG genotype. In the challenge study, we found that heterozygous piglets showed the significantly lower levels of viremia than homozygous piglets at 14, 21 and 28 dpc. Consistently, these heterozygous piglets also exhibited significantly higher ADWG than homozygous piglets. Therefore, in the current study, selection of boars based on SNP markers could increase the production of PRRS resistant piglets and the PRRS resistant pigs were found to be more resistant to PRRSV infection.

• Korean Journal of Veterinary Research
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• v.38 no.1
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• pp.77-83
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• 1998

돼지 생식기호흡기증후군(porcine reproductive and respiratory syndrome, PRRS) 바이러스가 웅돈에 감염되었을 경우에는 정충의 기형 등 정액의 질 저하와 더불어 정액에 바이러스가 함유되어 있어 종부시 모돈에 바이러스를 전파하는 것으로 알려져 있다. 감염된 웅돈의 정액으로 인공수정을 실시할 경우 농장의 모돈 전체에 순식간에 바이러스를 전파하여 막대한 피해를 유발할 가능성이 높다. 따라서 감염웅돈을 신속히 검색하여 격리함으로써 피해를 사전에 방지해야 하며, 이를 위해서 웅돈의 감염여부를 신속히 확진하는 진단법의 개발이 필요한 실정이다. PRRS의 진단을 위해서는 바이러스학적인 진단법으로는 바이러스 분리동정, 혈청학적인 방법으로 바이러스 분리동정이 필수적이나 검사시간이 많이 소요되고, 분리동정 자체가 까다로운 단점이 있다. 본 연구에서는 웅돈의 정액내에서 PRRSV 바이러스에 대한 유전자를 RT-PCR법으로 증폭하는 방법을 개발하였으며, 진단의 민감도를 높이기 위하여 Nested PCR법으로 재확인 할 경우, 바이러스의 역가가 $1TCID_{50}$만 함유되어 있어도 진단이 가능한 조건을 확립하였다. 이 방법을 이용할 경우 웅돈의 정액시료에 대한 PRRS 바이러스 감염여부를 신속, 정확하게 검색하여 감염웅돈을 통한 PRRS바이러스의 전파를 미리 차단할 수 있으므로 PRRS방제에 효과적으로 이용될 것으로 사료된다.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.8
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• pp.1096-1104
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• 2010

This bio-acoustic study was aimed at classifying the different porcine wasting diseases through sound analysis with emphasis given to differences in the acoustic footprints of coughs in porcine circo virus type 2 (PCV2), porcine reproductive and respiratory syndrome (PRRS) virus and Mycoplasma hyopneumoniae (MH) - infected pigs from a normal cough. A total of 36 pigs (Yorkshire${\times}$Landrace${\times}$Duroc) with average weight ranging between 25-30 kg were studied, and blood samples of the suspected infected pigs were collected and subjected to serological analysis to determine PCV2, PRRS and MH. Sounds emitted by coughing pigs were recorded individually for 30 minutes depending on cough attacks by a digital camcorder placed within a meter distance from the animal. Recorded signals were digitalized in a PC using the Cool Edit Program, classified through labeling method, and analyzed by one-way analysis of variance and discriminant analysis. Input features after classification showed that normal cough had the highest pitch level compared to other infectious diseases (p<0.002) but not statistically different from PRRS and MH. PCV2 differed statistically (p<0.002) from the normal cough and PRRS but not from MH. MH had the highest intensity and all coughs differed statistically from each other (p<0.0001). PCV2 was statistically different from others (p<0.0001) in formants 1, 2, 3 and 4. There was no statistical difference in duration between different porcine diseases and the normal cough (p>0.6863). Mechanisms of cough sound creation in the airway could be used to explain these observed acoustic differences and these findings indicated that the existence of acoustically different cough patterns depend on causes or the animals' respiratory system conditions. Conclusively, differences in the status of lungs results in different cough sounds. Finally, this study could be useful in supporting an early detection method based on the on-line cough counter algorithm for the initial diagnosis of sick animals in breeding farms.

• International Journal of Oral Biology
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• v.33 no.3
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• pp.77-82
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• 2008

Innate immune response is initiated by the recognition of unique microbial molecular patterns through pattern recognition receptors (PRRs). The purpose of this study is to dissect the expression of various PRRs in gingival epithelial cells of differentiated versus undifferentiated states. Differentiation of immortalized human gingival epithelial HOK-16B cells was induced by culture in the presence of high $Ca^{2+}$ at increased cell density. The expression levels of various PRRs in HOK-16B cells were examined by realtime reverse transcription polymerase chain reaction (RTPCR) and flow cytometry. In addition, the expression of human beta defensins (HBDs) was examined by real time RT-PCR and the amounts of secreted cytokines were measured by enzyme linked immunosorbent assay. In undifferentiated HOK-16B cells, NACHT-LRR-PYDcontaining protein (NALP) 2 was expressed most abundantly, and toll like receptor (TLR) 2, TLR4, nucleotide-binding oligomerization domain (NOD) 1, and NOD2 were expressed in substantial levels. However, TLR3, TLR7, TLR8, TLR9, ICE protease-activating factor (IPAF), and NALP6 were hardly expressed. In differentiated cells, the levels of NOD2, NALP2, and TLR4 were different from those in undifferentiated cells at RNA but not at protein levels. Interestingly, differentiated cells expressed the increased levels of HBD-1 and -3 but secreted reduced amount of IL-8. In conclusion, the repertoire of PRRs expressed by gingival epithelial cells is limited, and undifferentiated and differentiated cells express similar levels of PRRs.

• Korean Journal of Veterinary Research
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• v.39 no.4
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• pp.751-759
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• 1999

Plaque characteristics of porcine reproductive and respiratory syndrome (PRRS) virus isolates were examined using MARC-145 line cells. The plaque morphology of PRRS virus isolates was variable in size and heterogenic in population. Upon serial passages of the PRRS virus isolates on MARC-145 tells, heterogeneity was maintained but numbers of the large plaque size virus were increased with certain isolates. A PRRS virus isolate with variable plaque sizes was subcloned into 2 populations : small plaque ($H_S$) and large plaque ($H_L$) viruses. Growth kinetics of the subclones were then determined in MARC-145 cells, and production of the structural polypeptides was analyzed by SDS-PAGE. In a comparison of the growth kinetics, the $H_S$ virus showed higher infectivity titers during the first 48 hours but slower to reach the peak titier than $H_L$ virus did. In a nucleotide sequence comparison, differences of 4 nucleotides in open reading frames 5-6 gene were found between $H_S$ and $H_L$ viruses. Both the $H_S$ and $H_L$ clones produced 5 polypeptide bands with molecular weights of 15, 19, 26, 36 and 42 kD. The 5 bands were detected at 48 hours postinoculation (PI) with antisera to $H_L$ and another large plaque virus ($W_L$) and at 72 hours PI with $H_S$ virus antiserum. The present results demonstrate differences of biologic and molecular characteristics between the two PRRS virus plaque clones.

• Journal of Veterinary Clinics
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• v.34 no.2
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• pp.140-145
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• 2017

The goal of this study was to investigate risk factors associated with porcine reproductive and respiratory syndrome (PRRS) in pig farms in the Republic of Korea using logistic regression and a multilevel model. A cross-sectional study was applied to 305 pig farms with a questionnaire-based interview by veterinarians between March 2014 and February 2015. The questionnaire comprised eight categories: proximity to neighbors, disinfection, visitors, vehicles, insecticides, wild animals, gilts, and feeding. In total, 61 questions in eight categories related to pig farm biosecurity were investigated. Farms were classified as PRRS stable or unstable based on the results of an antibody test and PCR. For univariate analysis, keeping production records with computers (OR = 0.283, 95% CI = 0.056 - 1.425), accredited farm with no use of antibiotics (OR = 0.412, 95% CI = 0.134 - 1.269), reviewing health record of semen prior to purchasing (OR = 0.492, 95% CI = 0.152 - 1.589), complete isolation of runt pigs (OR = 0.264, 95% CI = 0.084 - 0.829), compulsory registering for visitors (OR = 0.424, 95% CI = 0.111 - 1.612), keeping records of insecticide history (OR = 0.406, 95% CI = 0.089 - 1.846), routine on-farm monitoring by veterinarians (OR = 0.314, 95% CI = 0.069 - 1.423), and use of on-farm checklist for biosecurity monitoring (OR = 0.313, 95% CI = 0.063 - 1.553) were found to decrease the probability of PRRS infection. Multivariate and multilevel analysis revealed only two factors, complete isolation of runt pigs (OR = 0.165, 95% CI = 0.045 - 0.602 and OR = 0.208, 95% CI = 0.055 - 0.782) and compulsory registering for visitors (OR = 0.106, 95% CI = 0.017 - 0.655 and OR = 0.119, 95% CI = 0.017 - 0.809) were found to decrease the probability of PRRS infection. The intracluster correlation coefficient of a province for multilevel model was 0.05. The results of this study might facilitate biosecurity measures for individual farms to reduce the probability of PRRS infection.

• Journal of the korean veterinary medical association
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• v.46 no.3
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• pp.279-287
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• 2010

돼지 번식기 및 호흡기 증후군 ( PRRS ; Porcine Reproductive and Respiratory Syndrome )은 우리나라를 포함한 전세계적으로 양돈산업에 가장 심각한 경제적인 손실을 끼치고 있는 질병으로, 조사자료에 의하면 미국의 경우 년간 손실 금액이 약 6천5백억(미화 560백만 달러)에 이르는 것으로 추정된다. 최근 우리나라도 피해의 정도가 정확히 조사 된 바가 없으나 현장의 골칫거리로 아직도 인식되어 다양한 시도 (Depop, Multi-site, Stabilization, etc)를 통해 사안별로 조치들을 하지만 발생정도는 줄어들지 않고 있다. 따라서 최근 차단방역에 대한 미국의 자료를 소개하오니 양돈현장 수의사들에게 도움이 되었으면 한다.

• 종축개량
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• v.19 no.6 s.72
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• pp.98-104
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• 1997

• The Korea Swine Journal
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• v.25 no.11 s.291
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• pp.171-175
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• 2003