• 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.

• 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.