The pathogenesis of Clostridium difficile-associated disease in neonatal pigs

Persistent Link:
http://hdl.handle.net/10150/280713
Title:
The pathogenesis of Clostridium difficile-associated disease in neonatal pigs
Author:
Keel, Michael Kevin
Issue Date:
2005
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Clostridium difficile-associated disease (CDAD) in neonatal pigs has emerged as a serious economic concern for swine producers throughout North America. The disease has been diagnosed clinically and reproduced in experimental inoculation trials in pigs, but little is known of the epidemiology or pathogenesis of the disease in pigs. Strain characteristics and distribution of C. difficile isolates from pigs, calves, dogs, horses, and humans were assessed by PCR-ribotyping. Porcine and bovine isolates were dominated by a single ribotype. This ribotype was uncommon among isolates from other host species; it was particularly uncommon from humans, suggesting there is little transfer of isolates between humans and calves or pigs. The reason for a single common ribotype circulating among distinct bovine and porcine populations is unknown. The intragastric inoculation of newborn pigs demonstrated their sensitivity to C. diffcile toxins. Toxin B (TcdB) surprisingly resulted in more severe lesions than Toxin A (TcdA). The two toxins together acted synergistically. Colon explants were sensitive to TcdA in a dose-dependent manner. However, TcdB did not cause significant lesions in the explants, nor was there any synergism with TcdA. Electron microscopy of colon explants treated with TcdA revealed severe, ultrastructural lesions that accrued in a dose-dependent manner by two h post infection. Direct immunohistochemistry assays demonstrated specific binding of biotinylated TcdA throughout the gastrointestinal tract of neonatal pigs. The density of bound toxin in different segments correlated with the severity of lesions in those segments from pigs gavaged with TcdA. TcdB did not bind any tissues, though it was fully active in cell-culture assays. A monoclonal antibody to Galalpha1-3beta1-4GlcNAc-R (alpha-Gal epitope), a putative receptor for TcdA in pigs, specifically bound the brush border of enterocytes, but the distribution of binding did not correlate with the distribution of TcdA binding. Specific TcdA binding to the plasmallema of microvilli was also confirmed by immunoelectron microscopy. By five min post inoculation some toxin was already visible in endosomes or free in the cytoplasm. TcdA localized to the mitochondria of epithelial cells and, less frequently, to the nuclei. Endothelial cells and leucocytes in the superficial lamina propria were similarly labeled by toxin.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Biology, Microbiology.; Agriculture, Animal Pathology.; Health Sciences, Pathology.; Biology, Veterinary Science.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Veterinary Science and Microbiology
Degree Grantor:
University of Arizona
Advisor:
Songer, J. Glenn

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleThe pathogenesis of Clostridium difficile-associated disease in neonatal pigsen_US
dc.creatorKeel, Michael Kevinen_US
dc.contributor.authorKeel, Michael Kevinen_US
dc.date.issued2005en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractClostridium difficile-associated disease (CDAD) in neonatal pigs has emerged as a serious economic concern for swine producers throughout North America. The disease has been diagnosed clinically and reproduced in experimental inoculation trials in pigs, but little is known of the epidemiology or pathogenesis of the disease in pigs. Strain characteristics and distribution of C. difficile isolates from pigs, calves, dogs, horses, and humans were assessed by PCR-ribotyping. Porcine and bovine isolates were dominated by a single ribotype. This ribotype was uncommon among isolates from other host species; it was particularly uncommon from humans, suggesting there is little transfer of isolates between humans and calves or pigs. The reason for a single common ribotype circulating among distinct bovine and porcine populations is unknown. The intragastric inoculation of newborn pigs demonstrated their sensitivity to C. diffcile toxins. Toxin B (TcdB) surprisingly resulted in more severe lesions than Toxin A (TcdA). The two toxins together acted synergistically. Colon explants were sensitive to TcdA in a dose-dependent manner. However, TcdB did not cause significant lesions in the explants, nor was there any synergism with TcdA. Electron microscopy of colon explants treated with TcdA revealed severe, ultrastructural lesions that accrued in a dose-dependent manner by two h post infection. Direct immunohistochemistry assays demonstrated specific binding of biotinylated TcdA throughout the gastrointestinal tract of neonatal pigs. The density of bound toxin in different segments correlated with the severity of lesions in those segments from pigs gavaged with TcdA. TcdB did not bind any tissues, though it was fully active in cell-culture assays. A monoclonal antibody to Galalpha1-3beta1-4GlcNAc-R (alpha-Gal epitope), a putative receptor for TcdA in pigs, specifically bound the brush border of enterocytes, but the distribution of binding did not correlate with the distribution of TcdA binding. Specific TcdA binding to the plasmallema of microvilli was also confirmed by immunoelectron microscopy. By five min post inoculation some toxin was already visible in endosomes or free in the cytoplasm. TcdA localized to the mitochondria of epithelial cells and, less frequently, to the nuclei. Endothelial cells and leucocytes in the superficial lamina propria were similarly labeled by toxin.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBiology, Microbiology.en_US
dc.subjectAgriculture, Animal Pathology.en_US
dc.subjectHealth Sciences, Pathology.en_US
dc.subjectBiology, Veterinary Science.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineVeterinary Science and Microbiologyen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorSonger, J. Glennen_US
dc.identifier.proquest3158111en_US
dc.identifier.bibrecord.b48137510en_US
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