• Journal of Veterinary Science
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• v.23 no.3
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• pp.41.1-41.15
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• 2022

Background: Proliferative enteritis caused by Lawsonia intracellularis undermines the economic stability of the swine industry worldwide. The development of cost-effective animal models to study the pathophysiology of the disease will help develop strategies to counter this bacterium. Objectives: This study focused on establishing a model of gastrointestinal (GI) infection of L. intracellularis in C57BL/6 mice to evaluate the disease progression and lesions of proliferative enteropathy (PE) in murine GI tissue. Methods: We assessed the murine mucosal and cell-mediated immune responses generated in response to inoculation with L. intracellularis. Results: The mice developed characteristic lesions of the disease and shed L. intracellularis in the feces following oral inoculation with 5 × 10⁷ bacteria. An increase in L. intracellularis 16s rRNA and groEL copies in the intestine of infected mice indicated intestinal dissemination of the bacteria. The C57BL/6 mice appeared capable of modulating humoral and cell-mediated immune responses to L. intracellularis infection. Notably, the expression of genes for the vitamin B12 receptor and for secreted and membrane-bound mucins were downregulated in L. intracellularis -infected mice. Furthermore, L. intracellularis colonization of the mouse intestine was confirmed by the immunohistochemistry and western blot analyses. Conclusions: This is the first study demonstrating the contributions of bacterial chaperonin and host nutrient genes to PE using an immunocompetent mouse model. This mouse infection model may serve as a platform from which to study L. intracellularis infection and develop potential vaccination and therapeutic strategies to treat PE.

• Korean Journal of Veterinary Service
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• v.33 no.3
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• pp.223-231
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• 2010

A total of 191 samples collected from the commercial swine farms located in Chungnam province were investigated by PCR to estimate the prevalence of Lawsonia (L.) intracellularis infection. In the group of the pigs with proliferative enteritis, 14 (93.3%) of 15 intestinal samples and 12 (80.0%) of 15 feces were positive in PCR. In contrast, a relatively low positive rate (18.0%, 29 of 161 samples) was determined in the group of normal healthy pigs. The group of pigs over 120 days showed the highest positive rates (26.8%, 15 of 56 samples). In the comparison of the sequences of 210bp for species specific fragments and 301bp for outer membrane protein, the isolates (L1. L2) showed almost 100% identity with the reference L. intracellularis (L08049, USA). For the sequences of partial 16s rDNA, the homologies among the 5 isolates (L1-L5) were 97.4% to 99.3%, and those of 5 sequences (L1-L5) versus 5 overseas reference strains of L. intracellularis ranged from 98.6% to 99.8%. In the comparison of the nucleotide sequences among 5 isolates and other species in Desulfovibrionales showed 82.4 to 99.5% identities. The 5 isolates shared relatively low identities (76.9% to 84.4%) with the species of alpha-proteobacteria. In phylogenetic analysis based on the 16s rDNA sequences, all of the 5 isolates (L1-L5) were located in the same branch with the strains of L. intracellularis that were previously isolated from the pigs in USA and China. Seven strains of Desulfovibrio sp. were clustered in the neighboring branches, whereas alpha and gamma Proteobacteria showed distant relationship with L. intracellularis strains. The present findings suggest that L. intracellularis infection is endemic in the swine farms in the regions, and that the domestic isolates maintained very limited genetic variation.

• Korean Journal of Veterinary Service
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• v.24 no.1
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• pp.43-50
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• 2001

Swine proliferative enteritis(SPE) caused by inかsoma intracellularis is a common enteric disaese of grower and finisher pig. Swine affected with SPE show variable clinical signs including diarrhea, weight loss, aberrant growth and death. The characteristic lesion of ileitis at necropsy is marked thickening of the last section of the small intestine. The inner lining of the thickened intestine proliferates almost like a cancer and curved rod bacteria(L intracellularis) are always seen inside the intestinal wall. Infected swine shed the organism in the feces. Isolation and growth of pure L intracellularis in vitro requires a suitable cell culture. This procedure is difficult and not a practical means of diagnosis, thus the polymerase chain reaction(PCR) test of feces can be used to determine whether a pig is shedding the infective organism. A sensitive assay based on amplification of a 319bp DffA fragment of the L intracellularis of Swine proliferative enteritis was attempted for the detection of the organism in the 62 feces of swine. L intracellularis was identified on three herds and detected in 6 fecal samples, representing a infection rate of 9.7%. The PCR was very sensitive and specific on the individual level. The PCR technique could be very useful for the diagnosis of this disease.

• Korean Journal of Veterinary Service
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• v.41 no.4
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• pp.245-250
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• 2018

Lawsonia intracellularis is the pathogenic agent of porcine proliferative enteritis (PPE). The bacterial pathogen infects the intestinal crypt cells which causes hyperplasia of the infected cells and leads to the process of intestinal pathogenesis. PPE includes some clinical maninfestations, including acute hemorrhagic diarrhea with sudden death in growing pigs and porcine intestinal adenomatosis, to a chronic diarrhea with reduced productivity of the infected pigs. The purpose of the present studies were carried out to determine L. intracellularis in livestock transport car of slaughterhouse. Distribution of L. intracellularis in livestock transport car were conducted using real-time polymerase chain reaction (real-time PCR) testing method, total 300 samples. Of 300 samples, 119 (39.7%) were detected as positive to L. intracellularis in livestock transport car. In seasonal analysis, 42 (28.0%) out of 150 samples in spring and summer season. 77 (51.3%) out of 150 sample in autumn and winter season. In regional analysis, 53 (88.3%) out of 60 cars and the detection ratio showed that regional variation in livestock transport car.

• Korean Journal of Veterinary Research
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• v.55 no.1
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• pp.61-63
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• 2015

Proliferative enteropathy caused by Lawsonia intracellularis is one of the most common enteric diseases in pigs. The objective of this study was to determine the prevalence of serum antibodies against L. intracellularis in the general swine population of Korea from 2005 to 2008. In total, 8,008 swine serum samples obtained from 1,001 herds were tested. The samples were analyzed with an immunoperoxidase monolayer assay to detect anti-L. intracellularis antibodies. The overall 4-year average true prevalence was 40.0% (CI: 39.4 - 40.6%) at the individual animal level and 71.9% (CI: 70.3-73.4%) at the herd level.

• Korean Journal of Veterinary Service
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• v.42 no.4
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• pp.301-304
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• 2019

The objective of this study was to determine the in vitro intracellular and extracellular minimum inhibitory concentrations (MICs) of 13 antimicrobials against one recently isolate Lawsonia intracellularis, the etiological agent of proliferative enteropathy (PE). The final MICs were assessed by counting the number of heavily infected cells (HICs;>30 bacteria per cell) using an immunoperoxidase monolayer assay. Enrofloxacin (InMIC; 1~2 ㎍/mL and ExMIC; 16 ㎍/mL) still presented the most notable antimicrobial susceptibility, and marbofloxacin (2 ㎍/mL and 8 ㎍/mL) was followed. Colistin (0.25 ㎍/mL and 2 ㎍/mL) presented a susceptibility followed by tylvalosin (1 ㎍/mL and 2 ㎍/mL). Florfenicol and lincomycin had the weakest susceptibility and amoxicillin, penicillin G, chlortetracycline, oxytetracycline, tiamulin, tilmicosin, and tylosin displayed weak susceptibility. Although some antibiotics showed decreased susceptibility patterns, they showed similar patterns to recent antibiotic susceptibility patterns in Korea. In addition, these results could be one of contributions in clinical fields.

• Korean Journal of Veterinary Research
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• v.39 no.1
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• pp.118-125
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• 1999

Porcine Proliferative Enteropathy(PPE) is an infectious enteric disease and a major cause of economic loss in swine industry due to weight loss, poor growth and sudden death in growing and finishing pigs at 6 to 20 weeks of age. PPE has been diagnosed by clinical signs, syndrom and lesions in the intestine in Korea. However, the diagnostic method had several problems in the detection of infected or carrier pigs. Therefore, in this study, we established the polymerase chain reaction(PCR) which was a fast, specific and sensitive method for identification of Lawsonia intracellularis (L intracellularis). We designed and synthesized primer on the 16S rDNA and p78 gene encoding L intracellularis. Specificity of the method was confirmed by comparison of the PCR results using other enteric bacteria and the study has shown that PCR method was sensitive to detect 1ng of genomic DNA as a template. Identity of the PCR products was confirmed by comparison of pattern of restriction endonuclease analysis with restriction enzyme Hae III and Pst I. Also, the PCR method was applicable to the naturally affected pigs with PPE. Based on the results from this study, the PCR method could be used as a fast and specific diagnostic tool for PPE.

• Korean Journal of Veterinary Service
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• v.32 no.4
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• pp.361-368
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• 2009

Porcine proliferative enteritis (PPE) is a transmissible gastroenteric disease caused by Lawsonia intracellularis. Clinically, PPE causes hemorrhagic diarrhea and sometimes death in growing pigs, but when the disease progresses to a chronic phase, the infected pig no longer displays significant symptoms. The purpose of the present studies were carried out to determine L. intracellularis in the pig farms and slaughter house, in Gyeongnam area. A survey of proliferative enteritis in pig was conducted using polymerase chain reaction (PCR) testing method, total 1,495 samples. PCR products showed a specific band at the 210bp, 329bp in the specimens of feces and mucosal scraping. Of 420 fecal specimens, 113 (26.9%) were identified as positive to PPE. Of 1,075 mucosal scraping specimens, 109 (10.1%) were identified as positive to PPE. Of total 1,495 specimens, 222 (14.8%) were identified as positive to PPE.

• Journal of Veterinary Clinics
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• v.28 no.1
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• pp.81-86
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• 2011

In grower pigs, enteric diseases are major economic problem in swine industries. Enteric diseases are attributed to numerous bacterial agents, such as Lawsonia (L.) intracellularis, Brachyspira (B.) hyodysenteriae, B. pilosicoli and Salmonella spp. Therefore we investigated the prevalence of enteric pathogens and found out the correlation of infectious agents in enteric diseases of grower pigs in Jeju-do using polymerase chain reaction (PCR) method. A total of 509 fecal samples of grower pigs from 49 pig farms of Jeju-do were collected from May 2006 to June 2007. Diagnostic confirmation was performed based on the detection of bacterial DNA from fecal samples. Based on the PCR methods, B. pilosicoli, B. hyodysenteriae, L. intracellularis and Salmonella spp. were detected in 82 (16.1%), 38 (7.5%), 15 (2.9%), and 12 (2.4%) fecal samples from grower pigs in Jeju-do, respectively. Single infection of enteric pathogen and mixed infection with more than 2 pathogens were detected in 110 (86.6%) and 17 (13.4%) grower pigs, respectively. These results suggest that B. pilosicoli and B. hyodysenteriae are main pathogens of diarrheal disease among grower pigs in Jeju-do. Therefore, accurate control strategy for enteric pathogens should be warranted in Jeju-do.

• Korean Journal of Environmental Biology
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• v.27 no.1
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• pp.48-57
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• 2009

The characteristics of physico-chemical factors and the species compositions of phytoplankton were investigated to analyze the marine ecosystem at the depths during summer in the coast of Dokdo (stations DOK1$\sim$3). The mean values of conductivity (32 mS cm$^{-1}$), total dissolved solids (45 mg L$^{-1}$), salinity (35.5 psu), total suspended solids (39 mg L$^{-1}$) were the highest in DOK1. The biomass (chl-${\alpha}$) of phytoplankton was the highest in the surface of station DOK1 (3.1 ${\mu}g$ L$^{-1}$). By means of physico-chemical factors (salinity, turbidity, chl-${\alpha}$, T-N, T-P and Si), the coast of Dokdo was estimated to be more polluted than the previous results in 2000. A total of 72 species in Dokdo were composed of 54 species (76.1%) for Bacillariophyceae and 13 species (18.3%) for Dinophyceae, 3 species (4.2%) for Chrysophyceae and 1 species (1.4%) for Cyanophyceae. The standing crops of phytoplankton were the highest (8.5 $\times$ 10$^4$ cells L$^{-1}$) at 20 m of station DOK1, while they were the lowest (1.65 $\times$ 10$^4$ cells L$^{-1}$) at 30 m of station 1. The dominance index was maximum (0.73) at 10 m of station DOK1 and was minimum (0.4) at 30 m of station 1. The diversity index was the highest (2.92) in the surface of station 2, while it was the lowest at 20 m (1.58). The dominant species of phytoplankton were Chaetoceros affinis (3.3 $\times$ 10$^4$ cells L$^{-1}$) at 20 m, Climacosphenia moniligera (2.8 $\times$ 10$^4$ cells L$^{-1}$) at 40 m and Melosira juergensii (1.7 $\times$ 10$^4$ cells L$^{-1}$) at 10 m of station DOK1. At the surface of station DOK2, the dominant species were Bacillaria paxillifer and Richelia intracellularis (1.4 $\times$ 10$^4$ cells L$^{-1}$, respectively), while it was Paralia sulcata (1.6 $\times$ 10$^4$ cells L$^{-1}$) at the surface of station DOK3. The station DOKl, where affected by upwelling, turbulence and convection due to the East Korean Warm Current, was the most eutrophicated water body in three stations. The monitoring of marine ecosystem in the coast of Dokdo should be continued to show the alternatives for water and species conservation and to purify the eutrophicated water body due to artificial pollutants as well as physico-chemical factors by the global warming, the climatic change, CO$_2$ etc.