• Journal of Veterinary Science
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• v.25 no.1
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• pp.4.1-4.14
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• 2024

Background: Lawsonia intracellularis is the causative agent of proliferative enteropathy and is associated with several outbreaks, causing substantial economic loss to the porcine industry. Objectives: In this study, we focused on demonstrating the protective effect in the mouse model through the immunological bases of two vaccine strains against porcine proliferative enteritis. Methods: We used live-attenuated Salmonella Typhimurium (ST) secreting two selected immunogenic LI antigens (Lawsonia autotransporter A epitopes and flagellin [FliC]-peptidoglycan-associated lipoprotein-FliC) as the vaccine carrier. The constructs were cloned into a Salmonella expression vector (pJHL65) and transformed into the ST strain (JOL912). The expression of immunogenic proteins within Salmonella was evaluated via immunoblotting. Results: Immunizing BALB/c mice orally and subcutaneously induced high levels of LI-specific systemic immunoglobulin G and mucosal secretory immunoglobulin A. In immunized mice, there was significant upregulation of interferon-γ and interleukin-4 cytokine mRNA and an increase in the subpopulations of cluster of differentiation (CD) 4⁺ and CD 8⁺ T lymphocytes upon splenocytes re-stimulation with LI antigens. We observed significant protection in C57BL/6 mice against challenge with 10^6.9 times the median tissue culture infectious dose of LI or 2 × 10⁹ colony-forming units of the virulent ST strain. Immunizing mice with either individual vaccine strains or co-mixture inhibited bacterial proliferation, with a marked reduction in the percentage of mice shedding Lawsonia in their feces. Conclusions: Salmonella-mediated LI gene delivery induces robust humoral and cellular immune reactions, leading to significant protection against LI and salmonellosis.

• 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.

• 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 Veterinary Service
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• v.44 no.4
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• pp.283-290
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• 2021

This is a study on the improvement of the chemical treatment method of the livestock carcass treatment newly introduced in the livestock infectious disease prevention method in order to improve the problems of the existing burial-centered carcass treatment method when a livestock infectious disease occurs. It was conducted to establish detailed treatment standards for the chemical treatment method of pig carcasses based on the results of proof of the absence of infectious diseases in pigs. After inoculating pig carcasses with 10 pathogens (6 viruses [FMDV, ASFV, CSFV, PCV2, PRRSV, PEDV] and 4 bacteria [Lawsonia intracellularis, Clostridium perfringens type C, E. coli, Salmonella Typhimurium]) It was treated at 90℃ for 5 hours in a potassium hydroxide (KOH) liquid solution corresponding to 15% of the body weight. This method liquefies all cadaveric components and inactivates all inoculated pathogens. Based on these results, it was possible to prove that chemical treatment of pig carcasses is effective in killing pathogens and is a safe method without the risk of disease transmission. Although there are problems to be solved in the processing and operation of the chemical treatment products of livestock carcasses, the chemical treatment method of livestock carcasses can be suggested as an alternative to the current domestic burial-centered livestock carcass treatment method, preventing environmental pollution, and contributing to public health.