Several mechanisms have been established by which E. coli can cause diarrhea. Some strains are enterotoxigenic and induce fluid secretion by colonizing the small bowel and by producing heat-labile or heat-stable enterotoxins. Other strains are enteroinvasive and mimic shigellae by invading and damaging colonic epithelial cells. A third group of strains, designated enteropathogenic E. coli (EPEC), are incriminated as agents of epidemic and endemic diarrheal disease in infants but have not been classified as enterotoxigenic or enteroinvasive. Recent studies from this laboratory revealed that EPEC and other E. coli enteric isolates do make a cell-associated toxin that is indistinguishable from the toxin of Shigella dysenteriae 1 (Shiga toxin). Two lines of evidence suggest that this E. coli Shiga-like toxin could be a virulence determinant in EPEC strains. First, the purified Shiga-like toxin of E. coli is a potent cytotoxin (1 pg = 1 HeLa cell cytotoxic dose) and is also an enterotoxin that can elicit fluid secretion in a rabbit ligated ileal segment. Second, the destruction of gut epithelial cell microvilli that is observed on small bowel biopsy of human infants with EPEC diarrhea is confined to regions of dense E. coli adherence, suggesting that an E. coli cell-associated cytotoxin might mediate the damage. The long range goals of this project are to analyze molecular mechanisms of toxinogenesis in E. coli and to determine if E. coli Shiga-like toxin has an essential role in the pathogenesis of EPEC diarrhea. Our studies will characterize the relationships between structure, antigenicity, and function of Shiga-like toxin and analyze the genetic basis for control of toxinogenesis at a molecular level. The results of these experiments will be applied for development of isogenic strains of enteropathogenic E. coli which differ only with respect to Shiga-like toxin production, and these strains will be compared for virulence in experimental animals. Our studies will contribute to an improved understanding of the molecular biology of Shiga-like toxin and its role in pathogenesis in gastrointestinal infections by E. coli. Such information is essential for assessing the potential contribution of antitoxic immunity in developing a successful method for immunizing against EPEC diarrhea.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Unknown (R22)
Project #
5R22AI020148-05
Application #
3563734
Study Section
Bacteriology and Mycology Subcommittee 1 (BM)
Project Start
1983-08-01
Project End
1988-07-31
Budget Start
1987-08-01
Budget End
1988-07-31
Support Year
5
Fiscal Year
1987
Total Cost
Indirect Cost
Name
U.S. Uniformed Services University of Health Science
Department
Type
DUNS #
City
Bethesda
State
MD
Country
United States
Zip Code
20814
Bunger, Joshua C; Melton-Celsa, Angela R; Maynard, Ernest L et al. (2015) Reduced Toxicity of Shiga Toxin (Stx) Type 2c in Mice Compared to Stx2d Is Associated with Instability of Stx2c Holotoxin. Toxins (Basel) 7:2306-20
Boisen, Nadia; Hansen, Anne-Marie; Melton-Celsa, Angela R et al. (2014) The presence of the pAA plasmid in the German O104:H4 Shiga toxin type 2a (Stx2a)-producing enteroaggregative Escherichia coli strain promotes the translocation of Stx2a across an epithelial cell monolayer. J Infect Dis 210:1909-19
Gray, Miranda D; Lampel, Keith A; Strockbine, Nancy A et al. (2014) Clinical isolates of Shiga toxin 1a-producing Shigella flexneri with an epidemiological link to recent travel to HispaƱiola. Emerg Infect Dis 20:1669-77
Melton-Celsa, Angela; Mohawk, Krystle; Teel, Louise et al. (2012) Pathogenesis of Shiga-toxin producing escherichia coli. Curr Top Microbiol Immunol 357:67-103
Steyert, Susan R; Sahl, Jason W; Fraser, Claire M et al. (2012) Comparative genomics and stx phage characterization of LEE-negative Shiga toxin-producing Escherichia coli. Front Cell Infect Microbiol 2:133
Scheutz, Flemming; Teel, Louise D; Beutin, Lothar et al. (2012) Multicenter evaluation of a sequence-based protocol for subtyping Shiga toxins and standardizing Stx nomenclature. J Clin Microbiol 50:2951-63
Zumbrun, Steven D; Hanson, Leanne; Sinclair, James F et al. (2010) Human intestinal tissue and cultured colonic cells contain globotriaosylceramide synthase mRNA and the alternate Shiga toxin receptor globotetraosylceramide. Infect Immun 78:4488-99
Panda, Aruna; Tatarov, Ivan; Melton-Celsa, Angela R et al. (2010) Escherichia coli O157:H7 infection in Dutch belted and New Zealand white rabbits. Comp Med 60:31-7
Smith, Michael J; Melton-Celsa, Angela R; Sinclair, James F et al. (2009) Monoclonal antibody 11E10, which neutralizes shiga toxin type 2 (Stx2), recognizes three regions on the Stx2 A subunit, blocks the enzymatic action of the toxin in vitro, and alters the overall cellular distribution of the toxin. Infect Immun 77:2730-40
Smith, Michael J; Carvalho, Humberto M; Melton-Celsa, Angela R et al. (2006) The 13C4 monoclonal antibody that neutralizes Shiga toxin Type 1 (Stx1) recognizes three regions on the Stx1 B subunit and prevents Stx1 from binding to its eukaryotic receptor globotriaosylceramide. Infect Immun 74:6992-8

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