The Distribution and Density of Clostridium difficile Toxin Receptors on the Intestinal Mucosa of Neonatal Pigs

Abstract

Abstract. Clostridium difficile is an enteric pathogen affecting a variety of mammals, but it has only recently been diagnosed as a cause of neonatal typhlocolitis in pigs. The most important virulence factors of C. difficile are 2 large exotoxins, toxin A (TcdA) and toxin B (TcdB). TcdA is a potent enterotoxin with effects on host tissues that are dependent upon receptor-mediated endocytosis of the intact toxin. TcdB is an effective cytotoxin, but it apparently does not bind receptors on intact mucosal epithelium. TcdB is much less toxic in vivo unless there is underlying damage to the mucosa, and it is not essential for the virulence of C. difficile. One hypothesis to explain the resistance of most species as neonates (e.g., humans and hamsters) is that they may lack significant numbers of TcdA receptors. The susceptibility of neonatal pigs suggests cells of the gastrointestinal mucosa express sufficient numbers of toxin receptors for lesion development. Immunohistochemical (IHC) assays documented specific binding of TcdA, but not TcdB, to the epithelium of the small and large intestine. The carbohydrate Gala1-3b1-4GlcNAc-R has been described as an important receptor for TcdA. However, IHC indicated a distribution on cell surfaces much different from that of TcdA binding, suggesting a specific interaction of toxin with an alternative receptor.

Fulminant Clostridium difficile Enteritis Causing Abdominal Compartment Syndrome

“…In human beings, the colon is the main site of C. difficile infection, but receptors for CD toxins have been isolated from the human small bowel, with substantial variability in small bowel toxin binding among individuals [1]. Animal studies have demonstrated C. difficile induced enteritis because of binding of toxin A to receptors in the small bowel [11][12][13]. In addition, as was demonstrated previously in transplanted human intestinal xenografts [14], C. difficile toxin B is a potent inflammatory enterotoxin and may contribute to intestinal damage in CDE.…”

Neutralization of Clostridium difficile Toxin A with Single-domain Antibodies Targeting the Cell Receptor Binding Domain

“…Purification of Toxins and Recombinant Fragments-TcdA and TcdB were isolated from C. difficile strain 10463 (ATCC, Manassas, VA) as described previously (65) and were stored in 50 mM Tris-HCl buffer, pH 7.5, at 4°C. Recombinant fragments of TcdA (amino acid residues 2304 -2710) and TcdB (amino acid residues 2286 -2366), which are fragments of the RBD, were cloned (as a BamHI-HindIII fragment for tcdA and a BamHI-EcoRI fragment for tcdB) into pTrcHisB (Invitrogen), transforming E. coli DH5␣MCR.…”

Antimicrobial Resistance, Toxinotype, and Genotypic Profiling of Clostridium difficile Isolates of Swine Origin

“…difficile is also associated with disease in animal species, including swine, calves, and horses (11,23,30). Extensive work has been conducted to describe C. difficile disease in swine; however, published data on the epidemiology and molecular characterization of C. difficile from swine herds is limited (9,30,33,35,37).…”