Accession Number : ADA434793


Title :   Toward Development of an Oral, Plant-Based Vaccine Against Escherichia coli O157:H7


Descriptive Note : Doctoral thesis


Corporate Author : UNIFORMED SERVICES UNIV OF THE HEALTH SCIENCES BETHESDA MD DEPT OF MICROBIOLOGY AND IMMUNOLOGY


Personal Author(s) : Judge, Nicole A


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a434793.pdf


Report Date : Jan 2004


Pagination or Media Count : 179


Abstract : Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is the most common infectious cause of bloody diarrhea in the United States, and a sequela of this infection, the hemolytic uremic syndrome (HUS), is the primary cause of acute renal failure in children in the U.S. The majority of U.S. cases of EHEC O157:H7 have occurred as a consequence of ingestion of undercooked, contaminated hamburger or produce and/or water contaminated with bovine manure. Intimin is the primary adhesin of EHEC O157:H7, and is required for colonization of neonatal calves. I hypothesized that an intimin-based vaccination strategy in calves might reduce colonization of cattle with EHEC O157:H7. To test this concept in a small animal model, I developed transgenic tobacco plant cells that expressed the full length or carboxy-terminal portion (Int261) of EHEC O157:H7 intimin and then immunized mice parenterally with intimin expressed from the plant cells, or fed mice the transgenic plant cells, or both. I was able to show that these mice not only generated an intimin-specific mucosal immune response when primed parenterally and boosted orally but also exhibited a reduced duration of EHEC O157:H7 fecal shedding after challenge. These results suggest that transgenic plants are attractive and feasible production and delivery systems for an intimin-based vaccine for cattle, and such a vaccine can reduce the duration of EHEC O157:H7 shedding in a small animal model. In addition, Shiga toxin type 2 (Stx2) is another important EHEC O157:H7 virulence factor that plays a critical role in the development of potentially fatal HUS in humans. I developed a toxoid of Stx2 by making site-directed changes to the nucleotide sequence of the Stx2 A subunit gene that abrogated cytotoxcity in vitro and in vivo. The Stx2 toxoid elicited toxin-neutralizing antibody when parenterally injected in mice.


Descriptors :   *ESCHERICHIA COLI , *DIARRHEA , *VACCINES , UNITED STATES , BACTERIA , THESES , BOVINES , COLONIES(BIOLOGY) , TOXINS AND ANTITOXINS , CHILDREN , TRANSCRIPTION(GENETICS)


Subject Categories : Genetic Engineering and Molecular Biology
      Microbiology
      Pharmacology


Distribution Statement : APPROVED FOR PUBLIC RELEASE