Electrical stimulation (ES) is known to guide the development and regeneration of many tissues. Use of low-frequency ES for therapeutic purposes has been increasing during the last decades. Mesenchymal stem cells (MSCs) represent an appealing alternative cell source for cartilage repair. There are studies that induce differentiation into cartilage cells by treating the growth factors in stem cells or altering the properties of stem cells by genetic modification. In this study, we exposed equine adipose tissue-derived MSCs (eAD-MSCs) to ES and assessed changes in the chondrogenic differentiation potential. The cells obtained from equine adipose tissue attached to culture plates and expanded in vitro. Flow cytometric analysis at third passage indicated that the cells were strongly positive for CD44, CD90, and CD105, but negative for CD13, CD34, and CD45. Next, ES was applied to eAD-MSCs cultured under condition of high-density micromass under ES of 10 V/cm, with duration of 10 ms and a frequency of 2.0 Hz for three days. Gene expression of chondrogenic markers such as collagen type II, Aggrecan, and Sox9 was analyzed at three days of ES. As a result, we observed the differentiation potential of eAD-MSCs into chondrocytes by specific ES in absence of exogenous growth factors. We also found that ES upregulated the expression of heat shock protein 70, which affects cartilage formation. This study may contribute to the differentiation of MSCs into chondrogenic lineage under specific ES condition.

Mesenchymal stem cells (MSCs) are capable of differentiating into mesenchymal tissue such as bone, cartilage, muscle, and adipose, and have been isolated and characterized from various species. Deer adipose tissue-derived MSCs (dAD-MSCs) have not been studied and deer bone marrow-derived MSCs (dBM-MSCs) have not been fully characterized. In this study, we firstly isolated MSCs from deer tissues and then compared characteristics of dAD-MSCs and dBM-MSCs. dAD-MSCs and dBM-MSCs exhibited significant increase in proliferation under low-glucose DMEM culture condition during 20 and 10 passages consecutive passages, respectively. Both cells expressed cell surface markers such as CD73, CD90, and CD105, but did not express CD34 and CD45. Two types of cells expressed stemness markers (Oct4, Sox2, and Nanog) and exhibited differentiation potential into mesodermal lineages. Both cells exhibited osteogenic and chondrogenic differentiation potential, but poor adipogenic differentiation potential. Specifically, dAD-MSCs have a greater capacity for chondrogenic differentiation potential compared to dBM-MSCs. Collectively, we successfully isolated dAD-MSCs from deer for the first time. This study suggests that adipose tissue of deer could be used as a source of deer MSCs.

Mesenchymal stem cells (MSCs) are multipotent cells capable of replicating as undifferentiated cells, and have the potential of differentiating into mesodermal lineages. Goats are commonly used as animal models for bone tissue engineering to test the potential of stem cells for bone regeneration. Goat MSCs isolated from bone marrow (BM) or adipose tissue (AD) should be evaluated using in vitro assays, prior to their application in a tissue engineering project. In this study, we compared the stem cell properties of MSCs derived from goat AD, BM and ear skin tissue (ESK). As results, BM and ESK-MSCs exhibited a spindle-shaped morphology comparable to that of AD-MSCs. Especially, BM-MSCs could be cultured for significantly longer periods and exhibited the greatest expansion capacity, whereas AD-MSCs had the shortest culture time and lowest growth rate. Also, we compared differentiation potentials of AD, BM and ESK-MSCs into adipogenic, chondrogenic, and osteogenic lineages through specific staining and quantitative real-time RT-PCR. Collectively, we successfully isolated ESK-MSCs from goat for the first time. This study suggests that adult skin tissue of goat could be used as a source of goat MSCs. Further studies are needed to show the more information for establishment and fully characterization of goat ESK-MSCs.

The objective of this study was to report the group mating of Asian Keelback snake, Hebius vibakari, in South Korea. On May 20, 2009, the group mating of H. vibakari was observed in the Maeng-gol do, Jindo-gun, Jeollanam-do, in the rocky area (107 m above sea level) on the ridge of the island. Six female and five male snakes made a form of mating behavior called “mating ball”. Two couples showed “tail-wrestling” which is the copulation behavior in snake species. During the mating, the temperature and humidity were 25.7°C and 59%, respectively. The result of this study was the first case report of the group mating in H. vibakari, a rare reptile.

환경부 지정 멸종위기 II급 종인 남생이의 복원을 위하여 개체증식 프로그램들을 개발해왔지만, 남생이의 번식생리에 대한 이해는 여전히 부족한 상태이다. 본 연구에서는 2014년 11월부터 2015년 10월 사이에 동면을 한 개체와 동면을 하지 않은 개체를 이용하여 성호르몬, 여포와 알의 수와 크기, 암ž수간의 행동상호작용의 계절적 변화를 연구하였다. 비록 동면 여부에 따라 다소의 편차는 있었지만, 암컷의 혈청 에스트라디올 농도는 7월부터 증가하기 시작하여 8월-10 월에 최고 농도를 보였으며, 수컷의 테스토스테론의 농도는 8-9월에 최고 농도를 보였으며, 3월에 가장 낮았다. 동면을 한 암컷들은 5월초에서 7월 중순 사이에 완전히 발달한 알을 가지고 있었으며, 산란은 6월 초순부터 7월 하순 사이에 이루어졌다. 반면, 동면을 하지 않은 암컷들은 이른 4월부터 이른 6월 사이와 8월 중순에서 11월 하순 사이에 알을 가지고 있었으며, 산란은 6월초, 10월 중순, 2월 초에 이루어졌다. 이러한 결과는 동면이 여포와 알의 정상적인 발달에 매우 중요한 역할을 함을 보여준다. 행동연구에서 암ž수간의 구애행동을 포함하는 행동상호작용은 8월 하순부터 증가되 어 10-11월에 최대를 보였다. 연구결과는 남생이의 짝짓기 기간이 성호르몬의 증가와 직접 연계되어 있지만, 여포와 알의 발달은 그렇지 않다는 것을 보여준다. 이러한 연구결과는 멸종위기종인 남생이의 성공적인 번식프로그램을 운영 하는데 매우 중요하게 사용될 것으로 판단된다.

남생이(Mauremys reecesii)는 파충강(Reptilia) 거북목 (Testudines) 남생이과(Geoemydidae)에 속하며, 오염되지 않은 일부 하천, 강이나 호수 등 유속이 느린 담수에 서식한 다. 국내에서는 제주도를 비롯한 도서지방을 제외한 한반도 전역에 서식하며, 국외에는 일본, 중국, 타이완에 분포한다. 경제개발 위주의 사회변화에 따른 극심한 환경오염, 인간에 의한 생태계 파괴, 남획, 기후변화에 따른 서식지 소실 등의 이유로 남생이의 개체수가 급격히 감소하고 있어 천연기념 물 제 453호와 환경부 멸종위기 야생생물 II급으로 지정되 어 보호되고 있다. 국제적으로는 IUCN (International Union for the Conservation of Nature)의 적색목록에 등재되었고, CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora)의 부속서 III에 포함되어 국제거래를 규제하고 있지만, 아직도 불법적으로 거래가 많 이 이루어지고 있는 실정이다. 지금까지 남생이의 분포현황 및 서식처 복원 등 남생이의 증식・복원을 위한 다양한 연구 들이 진행되었고, 교잡종, 종 식별, 계통진화학적 기원 등 분 자 수준의 연구가 이루어졌다. 그러나 아직까지 한국에 서식 하는 남생이 집단과 중국 남생이 집단과의 분자유전학적 연 관성에 대해 명확하게 밝혀진 예는 없는 실정이다. 본 연구는 남생이 미토콘드리아 DNA (mitochondrial DNA, mtDNA) cytochrome b(CYTB) 유전자를 이용하여 한국 남생이 집단 과 중국 남생이 집단의 mtDNA 다형성과 계통구조를 비교 하고, 동아시아 집단들과의 계통 유연관계를 밝히기 위하여 수행하였다. 남생이의 꼬리, 등갑, 혈액 등에서 genomic DNA를 추출하였고, CYTB 유전자 서열을 분석하였다. 남 생이 집단의 계통 유연관계를 확인하기 위해 기존에 해외에 서 보고된 남생이의 CYTB 서열도 분석에 이용하였다. 한국 남생이 집단(n=47)의 haplotype을 분석한 결과, 총 6가지 haplotype (Kor01-Kor06)으로 구분되었고, 대부분 Kor01 (n=19)과 Kor03 (n=23) haplotype에 포함되었다. 중국 남 생이 집단(n=40)도 6가지 haplotype (Chi01- Chi06)으로 나 뉘며, 30개체의 CYTB 서열이 Chi01에서 발견되었다. 한국 과 중국의 남생이들을 모두 함께 분석한 결과에서 CYTB 유전자 서열(n=87)은 7가지 haplotype (KChi01-KChi07) 으로 구분되었고, KChi01 (n=53)과 KChi03 (n=23)에서 많 은 개체들이 포함되었다. 동아시아 남생이의 CYTB 유전자 서열(n=226) 전체는 총 6가지 hapotype (Hap01-Hap06)으 로 구분되었다. 한국, 중국, 일본의 남생이 집단에서는 각각 4개의 haplotype이 있었으며, 대만 집단에서는 3개의 haplotype이 확인되었다. 중국 남생이 집단은 Hap01, Hap02, Hap04, Hap05에 포함되었고, Hap01이 85.0% (n=34)의 높은 빈도를 보였다. 한국 남생이 집단은 Hap01, Hap03, Hap04, Hap05에 포함되었고, Hap03에서 51.0% (n=24)로 높은 빈도를 보였다. 동아시아 남생이 집단의 CYTB 서열들 간의 유전적 거리지수는 0.0009-0.0212 사이 에 있는 것으로 나타났다. 동아시아 남생이 집단에서 발견 된 6가지 haplotype 중에서 한국 남생이의 CYTB 서열만으 로 구성된 haplotype은 확인되지 않았다. 반면, 한국의 남생 이가 다수 포함된 Hap03에서 중국 남생이의 CYTB 서열이 전혀 발견되지 않은 점은 한국 집단과 중국 집단이 지리적 으로 격리되어 진화한 결과로 추정되며, 현생 남생이에 대 한 한국 고유 집단과 중국 고유 집단을 나누는 기준이 될 수 있을 것으로 기대된다. 동아시아 남생이 집단에서 발견 된 mtDNA CYTB 서열의 haplotype들과 근연종의 CYTB 서열의 NJ tree 분지 양상에서, 동아시아 남생이 집단의 6개 의 haplotype들은 Hap04와 Hap05를 포함하는 하나의 cluster(A1)와 Hap01, Hap02, Hap03, Hap06을 포함하는 또 다른 cluster (A2)로 구분되었다. A2 cluster는 동아시아 남생이 집단의 대부분의 서열(n=215)을 포함하여 95.1%의 높은 빈도를 보였다. 동아시아 남생이 집단의 haplotype의 분포를 살펴보면, 전체적으로 국가별 남생이들이 서로 혼재 되는 경향을 보이지만, 각 국가별로 다수의 서열을 포함하 는 haplotype은 서로 구분되는 양상을 나타내었고, 남생이 집단의 6개의 haplotype들은 계통수 상에서 모두 단계통적 인 양상을 보이는 것으로 보아, 하나의 선조집단에서 진화 한 집단들로 판단되며, 추가적인 이동과 지리적인 격리 이 후 지역 내 진화과정을 거친 것으로 추정된다. 결과적으로 현재 한국의 남생이 집단은 우리나라 고유집단으로 추정되 는 것과 외부에서 유입된 것으로 추정되는 집단이 공존하고 있다고 판단된다. 한국을 비롯한 동아시아 남생이 집단의 mtDNA CYTB 유전자 서열을 토대로 유전적 다양성 및 계 통 유연관계를 분석한 결과 동아시아 남생이 집단은 진화과 정을 통해 유전적으로 모계가 다양한 개체가 서식하고 있다 고 판단된다. 비록 분석에 이용한 서열이 일부 지역에 편중 되어 있다는 한계가 있지만, 이번 연구에서 분석한 유전자 서열과 유전적 다양성 및 계통 유연관계는 향후 남생이의 보존 및 유전적 특성을 이용한 모계 분석 등에 유용한 정보 를 제공할 것이라 생각된다. 다양한 서식지에서 수집된 충 분한 수의 남생이를 대상으로 mtDNA의 다른 유전자 서열 이나 핵 DNA marker 등을 이용한 추가적인 분석이 이루어 진다면, 한국, 중국, 대만, 일본 등 동아시아 남생이의 모계 유전 및 계통 유연관계를 보다 명확히 해석할 수 있을 것으 로 기대된다.

Human hepatitis B virus (HBV) infection remains a serious public health problem worldwide, as it is one of the main risk factors for hepatocellular carcinoma (HCC). Cross-species transmission of HBV has been reported in non-human primates, and pigs may also be infected with HBV or an HBV-like agent. The purpose of this study was to demonstrate the presence of HBV antigens and anti-HBV antibodies in pig sera, providing further support for the existence of HBV or an HBV-like agent in pig populations. The HBV surface antigen (HBsAg) and HBV e antigen (HBeAg) in pig serum samples were detected using HBsAg and HBeAg ELISA Kits, respectively. Antibodies to HBsAg and the Hepatitis B core antigen (HBcAg) in serum samples were also detected using anti-HBsAg and anti-HBcAg antibody ELISA Kits, respectively. HBsAg and HBeAg were detected in 7 of 442 (1.6%) and 7 of 184 (3.8%) pig serum samples, respectively. Furthermore, antibodies specific to HBsAg and HBcAg were identified in 45 of 442 (10.2%) and 39 of 434 (9.0%) pig serum samples, respectively. However, neither HBV DNA nor antibodies to HBeAg were detected in 409 and 298 pig serum samples, respectively. HBV antigens and anti-HBV antibodies were both present in a considerable number of pig serum samples, suggesting that pigs could be infected with a variant HBV or an HBV-like agent. Further studies will be necessary to confirm cross-species infection of pigs with HBV.

The Korean National Residue Program (KNRP) use three plans for the sampling of domestic meats: monitoring, surveillance, and exploratory testing. We analyzed the results of monitoring and surveillance for residual veterinary drugs and pesticides in meat during 2012 and 2013. KNRP targets food-producing animals including cattle, pigs, chickens, ducks, sheep (goats), and horses. Sampling mainly focuses on veterinary drugs and pesticide residues found in tissues such as muscle, kidney, and liver. A total of 548 residue violations occurred between 2012 and 2013, mainly in pigs (427 violations) and cattle (113 violations). The most commonly found compounds were antimicrobials such as penicillins, fluoroquinolones, aminoglycosides, tetracyclines, sulfonamides, and macrolides. Pig residue violations were mainly for the presence of penicillins (34%) and fluoroquinolones (28%), while most residue violations in cattle were due to the presence of penicillins (32%) and aminoglycosides (27%). The overall rates of violations were 0.21% in 2012 and 0.10% in 2013. A major cause of violations was the failure to follow the appropriate withdrawal periods (68.8%). The results of the KNRP were analyzed to provide information on agricultural chemical residues that are of public health concern and to help control and prevent residue violations for ensuring food safety.

Mycotoxins, such as aflatoxin B1 (AFB1), deoxynivalenol (DON), fumonisin B1 (FMB1), ochratoxin A, T2 toxin, and zearalenone, are found in numerous vegetables. Mycotoxin accumulation in food and feed poses serious health risks to humans and animals because of carcinogenic, mutagenic, teratogenic, and toxic properties. In addition, mycotoxins cause large economic losses in commercial crop production, food and feed processing, and animal husbandry worldwide. In this study, an analytical method for the simultaneous analysis of the levels of AFB1, DON, and FMB1 in cow blood with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed and validated. AOZTM and Myco6in1TM multitoxin immunoaffinity columns and an OasisTM reversed-phase solid-phase extraction Hydrophilic-Lipophilic-Balanced columns were used to purify and concentrate the blood samples. Extracts that contained AFB1, DON, and FMB1 had average recovery of 64.0%, 98.0%, and 89.9%, respectively. In conclusion, we used LC-MS/MS to detect several important toxicological mycotoxins in cow blood. The multimycotoxin method, which detected and quantified the levels of AFB1, DON, and FMB1 can be used in animal pilot studies to monitor simultaneous exposure to major mycotoxins.

본 연구는 농업유전자원센터에 보존되어있는 불가리아 재래종 고추 유전자원 61 점을 대상으로 농업형질을 조사하고, 22개의 분자마커(SSR marker)를 이용하여 불가리아 재래종 고추 유전자원의 유전적 다양성 및 집단분석을 통하여, 자원보존 및 효율적인 작물 육종을 위한 기초정보를 제공하고자 본실험을 수행하였으며 결과는 다음과 같다. 1. 파종 후 발아까지 소요일수는 최소 11일에서 최대 26 일,평균 16.9 일이었고 개화 소요일수는 최소 48일, 최대 65일, 평균 56.9일이었으며 성숙까지의 소요일수는 최소 73일, 최대 98일, 평균 90.7일이었다. 2. 농업형질의 특성을 바탕으로 PCA 분석을 이용하여 불가리아 고추의 다양성을 분석한 결과, 파종 후 개화까지의 소요일수에 따라 조생종, 중생종, 만생종 3개의 그룹으로 나눌 수있었다. 3. 61점의 고추자원에 대하여 22개 SSR 마커에 의해 나타난 대립유전자 (allele)수는 총 82개였다. 마커당 평균 allele수는 3.7 개였고, allele 수의 범위는 2개에서 5개로 확인되었다. 유전적 다양성을 나타내는 PIC 값의 범위는 0.061-0.636이었으며 평균 PIC 값은 0.349로 확인되었다. 4. 분자마커(SSR)를 이용하여 UPGMA, PCoA, STUCTURE 분석을 통한 고추의 다양성 및 집단 구조를 분석한 결과, 3개의 그룹으로 나뉘어졌다. 결론적으로, 농업형질 특성을 바탕으로 한 불가리아 재래종고추의 다양성과 분자학적 특성을 이용한 다양성 결과와는 차이가 있었다.

Korean freshwater turtles are divided into native turtles, Chinemys reevesii in Geoemydidae, Pelodiscus sinensis in Trionychidae, and imported turtles, Trachemys scripta elegans, T. s. scripta, Pseudemys rubriventris and Ocadia sinensis. In this study, we determined the distribution of Korean freshwater turtles based on a field study and literature study, and considered the taxonomic position of unidentified native turtles. The study was carried out between May 2010 and November 2011 during the day time, and the capturing tool used to collect turtles consisted of net and metal frame. C. reevesii and P. sinensis were found in 16 and 11 places, respectively. C. reevesii, which inhabits the Korean peninsula, is a taxonomically controversial species, but it is presumed that the turtle belongs to Mauremys. Moreover recent taxonomic studies of the soft-shell turtle have shown that the Korean native species is P. maackii, and P. sinensis was imported from abroad and has been in the natural habitats of Korea since 1970s. The exterior shape and skeletal form of P. maackii and P. sinensis are nearly similar. However, the skin color and yellow spots on the shell could be used to distinguish the two species.

Porcine has been known to have a great impact on the studies of organ transplantation, biomaterial production and specific biomodel development such as transgenic animals. To achieve such therapeutic purposes, establishment of porcine embryonic stem cells (pESCs) will be needed. Especially, in vitro differentiation toward neural cells from pESCs can be a useful tool for the study of early neural development and neurodegenerative disorders. In addition, these cells can also be used in cell replacement therapies and drug development for neuroprotective and/or neurotoxic reagents. Although several studies reported the successful isolation of pES-like cells, it has been a big challenge to determine optimal conditions to generate pESCs without loss of pluripotency for a long time. The present study was performed for generation and characterization of putative pESCs, and differentiation into neurons and astrocytes. In this study, porcine blastocysts were produced by parthenogenetically activated oocytes. The putative pESCs were cultured in pESC growth media supplemented with a growth factor and cytokines (bFGF, LIF and SCF). Subculture of pESCs was conducted by mechanical dissociation using syringe needles after 4-5 days of incubation. As results, six putative pESC lines were maintained over thirty passages. The putative pESCs were compact, round, flat, and single layered, which were similar to human embryonic stem cell morphologically. Six pES-like cells were positive for alkaline phosphatase activity at every three passages. Furthermore, Oct-3/4, Sox-2, Nanog and SSEA-4 were shown to be expressed in those cells. Also, normal karyotypes of pESCs were observed by Giemsa-staining. Differentiation potential into the three germ layers of the putative pESCs was demonstrated by the formation of embryoid bodies (EB). Besides, the study of ESC is very important in aspect of its application to not only the cell-based replacement therapies but also cellular differentiation research. Our results also showed that RA and N2 supplements activated the neural differentiation in pESC5. Neurofilament-l60 were expressed in neural precursor cells. The expression of markers for specific neural lineages, such as Microtubule-associated protein-2 expressed in matured neuron, was also induced from embryonic neural progenitors. In summary, the pESCs were generated from the parthenogenetically activated blastocysts and the typical characteristics of the cells were maintained for the long term culture. Furthermore, it was successful to differentiate the pESCs into various neural lineages through in vitro neurogenesis system. Eventually, pESCs will be excellent biomedicine in incurable and/or zoonotic diseases by regenerating the damaged tissue.

Rabies is one of the most dreadful diseases known to human. Annually, more than 55,000 human deaths occur throughout the world. The main transmitters are dogs. In South Korea, urban rabies is eliminated after massive national vaccine programme but rabies is still present in wildlife around northern part of the country near the border. Occasionally, rabies cases are still reported and there are spill over cases from racoon dogs. No human case was reported since 2005. Therefore, risk of rabies from exporting domestic dogs and cats from South Korea is very low. Hence, foreign rabies can be introduced by importing wild carnivores and unvaccinated dogs and cats under the age of three months since the South Korean legislation does not cover them. Therefore, it is essential to update current import regulation to minimise the risk of rabies.

Rabies is a zoonotic disease that causes severe destruction to the central nerve system which is usually fatal. It is one of the most important disease around the world and particular in Asia because of the high costs of prevention and post-exposure treatment. After the recurrence of sylvatic rabies in 1993, the number of raccoon dog mediating rabies cases in Korea has maintained annually until 2011. To better understand the current rabies epidemics in Korea, Korean rabies isolate (SKRBV0601GY) from Gyeonggi province in 2006 was compared with previous isolates in Korea and with isolates originating from the North-East Asia, such as Japan, China and Russia, based on complete nucleoprotein (N) gene sequences. By comparison of the N genes among these viruses, SKRBV0601GY revealed that nucleotide similarity ranged from 97.7 to 99.7%, 96.4 to 97.5%, 91.4 to 96.3%, 89.2 to 90% and 86.1 to 88.1% with Korean isolates, "Arctic-like-2" viruses, "Arctic" viruses, Russian group C - E and Chinese isolates, respectively. Phylogenetic analyses of the isolates revealed that the Korean isolate in 2006 belonged to Korean group B. The topology of the phylogenetic tree of Korean isolates related not the species and year of isolation but the geological location of the virus isolates. All of the Korean isolates showed close relationship to the "Arctic-like-2" virus (Russian group B) more than the "Arctic" virus (Russian group A) and all of the Chinese isolates (Chinese group A, B and C). The "Arctic-like-2" virus group contains the Japanese isolate and Russian group B viruses, originating from the south of East Siberia and Far East in Russia. These molecular data demonstrated that the current rabies epizootic in Korea developed independently of Chinese groups and originated from the "arctic-like-2" viruses in detail.

Canine parvovirus (CPV) type 2a (CPV-2a) has recently been identified as the main genotype circulating in the dog population in South Korea. Although CPV vaccines protect domestic dogs from CPV-2 infection, the efficacy of commercial live or inactivated CPV vaccines against CPV-2a has not been reevaluated. In this study, dogs were immunized with one of 7 commercial CPV vaccines (4 modified live and 3 inactivated vaccines) followed by challenge with CPV-2a strain, KV0901 that had been isolated from naturally infected dog in 2009. All dogs vaccinated twice with 4 commercial modified live CPV vaccines were seroconverted (geometric mean HI titer > 190.2) and most of dogs were completely protected against virulent CPV-2a strain infection. The dogs inoculated with 3 commercial inactivated CPV vaccines were also seroconverted and showed a slight loss of appetite and light diarrhea for 4 days after challenge and returned to normal at 5 days post challenge. However, the non-vaccinated dogs revealed the typical clinical signs of CPV infection including haemorrhgic diarrhea. In conclusion, the 4 live CPV vaccines licensed in Korea cross-protected dogs against virulent challenge with CPV-2a and are applicalble to pet dogs for the prevention of CPV infection.

This study was performed to estimate the seroprevalence of PRRSV in breeding farms in Jeju 2008 using a commercial enzyme-linked immunosorbent assay (ELISA) kit. The tested sera were randomly collected from a total of 1,947 sera from 9 breeding farms unvaccinated in Jeju. As a result, all breeding farms were seropositive for PRRSV. Seven hundred-eighty six of 1,947 sera (40.4%) were positive for PRRSV. Seropositve rate of PRRSV infection in 9 farms showed various levels: 1%, 8.9%, 9.1%, 43%, 46.9%, 48.2%, 51.6%, 60.9%, 85.5%, respectively. The results confirmed that PRRSV infection has been prevailing in breeding farms in Jeju. Also, these results must be taken into a consideration in strategy establishment for the control and eradication of PRRS.

The lung and lymph node samples were collected from 786 pig farms associated with wasting and respiratory syndrome during 2005～2009. All samples were tested for the detection of porcine reproductive and respiratory syndrome virus (PRRSV) and the differentiation of its genotype using reverse transcriptase-polymerase chain reaction (RT-PCR). 643 farms (81.8%) of the pig farms examined were positive for PRRSV, of which 57.2% accounted for PRRSV type 1 and 70.2% accounted for PRRSV type 2. Furthermore, 37.5% of the farms positive for PRRSV, showed the coexistence of two genotypes. The results indicate that the PRRSV infections of single genotype or two genotypes are very common in Korean pig farms.