The Shiga toxin (Stx)-producing Escherichia coli (STEC) serotype 0157:H7 is the most common infectious cause of bloody diarrhea, or hemorrhagic colitis (HC), in the U.S. with an estimated incidence of 63,153 cases per annum. Moreover, the hemolytic uremic syndrome (HUS), a sequela of STEC infection, is the most frequent basis for acute kidney failure in U.S. children. In addition, 0157;H7 infection is the leading cause of death in children aged 0-4 years from bacterial infections acquired through food. STEC may produce Stx1 and/or Stx2 and/or a variant of Stx2 (Stx2c and Stx2dact are the most important subtypes associated with human disease). Due to the potential severity of STEC infection, the very low 50% infectious dose, and the easy transmissibility from person to person, 0157:H7 is considered a category B biological threat by the CDC. Eariier this year, a large outbreak with more than 4000 illnesses and 800 cases of HUS occurred in Germany;the outbreak was caused by a ?. coli O104:H4 strain that makes Stx2. The O104:H4 isolate from the outbreak is an enteroaggregative E. coli (EAEC) strain that acquired the phage that carries sfx2, and, as such, can also be considered an STEC. The long-term goals of this project are to define at the molecular, cellular, and whole animal levels the pathogenic mechanisms by which STEC cause disease and to test strategies to prevent and treat these illnesses.
The specific aims are to: 1) examine the relative role(s) of Stx2 and Stx2c in 0157:H7 colonization and in toxicity for mice;2) investigate the mechanisms of enhanced toxicity of elastase-treated (ET)-Stx2dact;3) evaluate the role of diet in host (mouse) response to STEC;and 4) determine the transmissibility of the phage that carries stX2 in O104:H4 with or without ciprofloxacin (cpx) and the impact of cpx treatment on O104:H4 disease.
STEC has a very low 50% infectious dose, can spread easily from person to person, and causes potentially lifethreatening sequelae after infection. As an outcome of this project, we will further delineate the steps by which this pathogen causes disease, which, in turn, may facilitate the creation of more targeted strategies to interfere with the infectious and intoxication processes.
|Russo, Lisa M; Melton-Celsa, Angela R; Smith, Michael J et al. (2014) Comparisons of native Shiga toxins (Stxs) type 1 and 2 with chimeric toxins indicate that the source of the binding subunit dictates degree of toxicity. PLoS One 9:e93463|
|Russo, L M; Melton-Celsa, A R; Smith, M A et al. (2014) Oral intoxication of mice with Shiga toxin type 2a (Stx2a) and protection by anti-Stx2a monoclonal antibody 11E10. Infect Immun 82:1213-21|
|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 Hispañiola. Emerg Infect Dis 20:1669-77|
|Zangari, T; Melton-Celsa, A R; Panda, A et al. (2014) Enhanced virulence of the Escherichia coli O157:H7 spinach-associated outbreak strain in two animal models is associated with higher levels of Stx2 production after induction with ciprofloxacin. Infect Immun 82:4968-77|
|Bunger, Joshua C; Melton-Celsa, Angela R; O'Brien, Alison D (2013) Shiga toxin type 2dact displays increased binding to globotriaosylceramide in vitro and increased lethality in mice after activation by elastase. Toxins (Basel) 5:2074-92|
|Zumbrun, Steven D; Melton-Celsa, Angela R; Smith, Mark A et al. (2013) Dietary choice affects Shiga toxin-producing Escherichia coli (STEC) O157:H7 colonization and disease. Proc Natl Acad Sci U S A 110:E2126-33|
|Zangari, Tonia; Melton-Celsa, Angela R; Panda, Aruna et al. (2013) Virulence of the Shiga toxin type 2-expressing Escherichia coli O104:H4 German outbreak isolate in two animal models. Infect Immun 81:1562-74|
|Mohawk, Krystle L; O'Brien, Alison D (2011) Mouse models of Escherichia coli O157:H7 infection and shiga toxin injection. J Biomed Biotechnol 2011:258185|
|Mohawk, Krystle L; Melton-Celsa, Angela R; Robinson, Cory M et al. (2010) Neutralizing antibodies to Shiga toxin type 2 (Stx2) reduce colonization of mice by Stx2-expressing Escherichia coli O157:H7. Vaccine 28:4777-85|
|Mohawk, Krystle L; Melton-Celsa, Angela R; Zangari, Tonia et al. (2010) Pathogenesis of Escherichia coli O157:H7 strain 86-24 following oral infection of BALB/c mice with an intact commensal flora. Microb Pathog 48:131-42|
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