Browsing by Subject "Lawsonia intracellularis"

Now showing 1 - 6 of 6
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    A Cell Proliferation and Inflammatory Signature is Induced by Lawsonia intracellularis Infection in Swine
    (2018-07-24) Leite, Fernando, L; Abrahante, Juan, E; Vasquez, Erika; Vannucci, Fabio; Gebhart, Connie, J; Nathan, Winkelman; Mueller, Adam; Jerry, Torrinson; Rambo, Zachary; Isaacson, Richard, E; isaac015@umn.edu; Isaacson, Richard, E
    Lawsonia intracellularis causes porcine proliferative enteropathy. This is an enteric disease characterized by thickening of the wall of the ileum that leads to decreased growth and diarrhea of animals. In this study, we investigated the host response to L. intracellularis infection by performing transcriptomic and pathway analysis of intestinal tissue in groups of infected and non-infected animals at 14, 21 and 28 days post challenge. The data deposited here are BAM files.
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    Evaluation of swine intestinal epithelial responses to luminal stimuli
    (2023-01) Medida, Ramya Lekha
    Gastrointestinal (GI) tract health or ‘gut health’ is synonymous with the overall health and wellbeing of all animals. Gut health is the result of multiple factors, including proper diet, effective digestion and absorption, adequate immune status, and optimal microbiome. The epithelium of GI tract acts as a barrier for the luminal contents and plays an important role in gut health. Understanding the intestinal epithelial responses to various luminal stimuli can help improve overall animal health, by providing insights for better diet design and for the development of alternative disease treatment and prevention strategies. In this dissertation, the effects of micronutrient supplementation and bacterial infection on the intestine and intestinal epithelium responses have been evaluated with L. intracellularis as a case study for bacterial luminal stimuli and dietary zinc (Zn) as a case study for nutrient stimuli.
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    Lawsonia intracellularis disease control and epidemiology.
    (2009-09) Wattanaphansak, Suphot
    Proliferative enteropathy (PE) is an important enteric disease in grower and finisher pigs caused by an obligate intracellular bacterium, Lawsonia intracellularis. The overall aims of this thesis were to obtain more information about the in vitro activity of antimicrobials and disinfectants against L. intracellularis and to develop a new quantitative PCR assay. To determine the minimum inhibitory concentration (MIC) of antimicrobials against L. intracellularis, ten isolates obtained from North America and Europe were tested against 6 antimicrobials using a modified tissue culture assay. In vitro results found that carbadox, tiamulin, and valnemulin were the most active antimicrobials, chlortetracycline and tylosin were intermediately active, lincomycin was the least active against L. intracellularis, and the antimicrobial sensitivity patterns differed across isolates. We next evaluated the effectiveness of the modified tissue culture and direct count method with special fluorescence to determine in vitro disinfectant activity against L. intracellularis. The outcomes of both methods predicted similar in vitro bactericidal activities against L. intracellularis with a high degree of correspondence. This suggests that either assay would be appropriate in determining the bactericidal activity of disinfectants against L. intracellularis. Based on our in vitro results, we predict that a powder disinfectant (Stalosan® F), DC&R®, Roccal®-D, Synergize®, and Virkon®-S would perform well under field conditions, while Certi-Dine®, Nolvasan®-S, and Tek-Trol® would be less active against L. intracellularis. Finally, a new quantitative PCR assay was developed using a SYBR green system. The assay showed negative results when DNA from 16 other species of enteric bacteria as well as 20 negative control samples of pig feces was tested. Quantitative estimates from the assay were roughly 2-fold lower than the expected values across all dilutions of pure culture and spiked feces. Validation results indicated that this new qPCR is sensitive, specific, reliable, accurate, and precise for the detection and quantification of L. intracellularis in different types of samples. In conclusion, the results of these investigations update and expand upon existing information about the in vitro antimicrobial and disinfectant activities against L. intracellularis. Further, the development of a new, accurate, and precise qPCR assay will facilitate future epidemiology studies.
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    Microbiome and Immune Response to Salmonella enterica serovar Typhimurium and Lawsonia intracellularis Infection in Swine
    (2018-05) Leite, Fernando Lopes Leivas
    Salmonella enterica is a leading cause of foodborne illness world-wide. In the US alone Salmonella is responsible for over 1 million cases of disease a year in humans and causes an estimated loss of more than 3.5 billion dollars annually. Pork is frequently associated with food borne illnesses caused by S. enterica in humans, many of which are attributed to Salmonella enterica serovar Typhimurium. Efforts to reduce the incidence of salmonellosis due to meat consumption have mainly remained ineffective. This study extends previous findings that pigs are more susceptible to colonization by Salmonella enterica when co-infected with the pathogen Lawsonia intracellularis. We determined the composition of the porcine gut microbiome in response to co-infection to determine how potential disturbances caused by L. intracellularis could favor S. Typhimurium. This analysis revealed that L. intracellularis led to a decreased abundance of Clostridium species and Clostridium butyricum in addition to other changes that may favor S. Typhimurium. We also investigated if vaccination against L. intracellularis could have an effect on the shedding S. Typhimurium and found that vaccination significantly reduced S. Typhimurium shedding in animals co-infected with L. intracellularis. To better understand the host response to L. intracellularis, we performed transcriptome analysis of infected mucosal tissue and found that infection induced a signature of genes associated with inflammation and proliferation in the gut. We then tested zinc supplementation, which is known to impact immune function, and found that zinc amino acid supplementation led to a significant reduction of lesions caused by L. intracellularis. Finally, we investigated whether co-infection of enterocytes in vitro caused increases in certain inflammatory cytokines. We found that L. intracellularis up regulated expression of IL-8 and TNFα, two pro-inflammatory cytokines crucial to the pathogenesis of S. Typhimurium infection. This research suggests that increased inflammation mediated by L. intracellularis along with changes in microbiome composition are likely responsible for enhancement of S. Typhimurium infection in swine. We have also identified that L. intracellularis vaccination and zinc amino acid complex supplementation are two promising alternatives to the use of antimicrobials in swine.
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    Proliferative Enteropathy: Pathogenesis and Host Adaptation
    (2013-03) Vannucci, Fabio Augusto
    Proliferative enteropathy (PE) is an infectious disease caused by an obligate intracellular bacterium, Lawsonia intracellularis, and characterized by thickening of the intestinal epithelium due to enterocyte proliferation. The overall goals of this thesis were to improve the understanding of the pathogenesis of PE by evaluating phenotypic traits, genome variations and transcriptome patterns of L. intracellularis infection and to evaluate the adaptation of the bacterium to porcine and equine hosts. In the first section, the susceptibility of pigs to a homologous porcine L. intracellularis isolate continuously grown in vitro was assessed. A loss of virulence after 40 passages of the bacteria in culture was established. The comparative whole genome analysis of the pathogenic (low passage) and non-pathogenic (high passage) isolates identified the loss of a prophage-associated genomic island in the non-pathogenic variant. This chromosomal island proved not to be essential for the virulent phenotype, since it was not identified in horses clinically affected with PE. However, this genetic element was associated with host-adapted L. intracellularis variants. While pathogenic porcine isolates harbor this genetic element, it was absent in equine isolates and PE-affected horses. Gene expression profiling of a porcine pathogenic isolate showed a wider transcriptional landscape compared with the non-pathogenic variant. In addition, genes highly activated in vitro by the pathogenic variant also were significantly expressed in vivo. However, genes identified in the genomic island were not expressed by intracellular bacteria either in vitro or in vivo. The proliferative changes exhibited by the infected enterocytes in vivo were associated with deregulation of the G1 phase of the host cell cycle and repression of membrane transporters related to nutrient acquisition, characterizing a malabsorptive syndrome as the major mechanism involved in the poor performance and growth of affected animals. Finally, an alternative method for cultivation of L. intracellularis was developed in order to perform a cross-species experimental study evaluating the susceptibility of pigs and horses to a porcine and an equine L. intracellularis isolate. Evident clinical signs, longer periods of bacterial shedding and stronger serologic immune responses were observed in animals infected with species-specific isolates indicating that host susceptibility is driven by the origin of the L. intracellularis strain.
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    Vaccination Against Lawsonia intracellularis Decreases Shedding of Salmonella enterica serovar Typhimurium in Co-Infected Pigs and Alters the Gut Microbiome
    (2017-11-09) Leite, Fernando L L; Singer, Randall S; Ward, Tonya; Gebhart, Connie J; Isaacson, Richard E; isaac015@umn.edu; Isaacson, Richard
    Salmonella enterica is a leading cause of foodborne illness worldwide and pork can serve a source of infection. In this study, we investigated if vaccinating pigs against Lawsonia intracellularis, a common pathogen of swine that has previously been shown to favor Salmonella enterica infection, confers protection against Salmonella enterica serovar Typhimurium. We investigated the underlying changes in the gut microbiome mediated by single S. Typhiumurium infection compared to co-infection with L. intracellularis as well as the effect of vaccination on the microbiome. In this study, a total of five treatment groups were used: 1) challenged with S. Typhimurium alone (Sal), 2) challenged with both S. Typhimurium and L. intracellularis (Sal Law), 3) challenged with S. Typhimurium and vaccinated against L. intracellularis (Sal Vac), 4) challenged with both S. Typhimurium and L. intracellularis and vaccinated against L. intracellularis (Sal Law Vac), and 5) non-infected control (Control).