U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 close



Research
                Research Home
                            National Programs
                            Research Projects
                            Scientific Manuscripts
                            International Engagement
                            Scientific Software/Models
                            Databases and Datasets
                            Office of Scientific Quality Review
            Media
                News & Features
                            Multimedia
                            Briefing Room
                            Down on the Farm
                            Press Room
                            Science in Your Shopping Cart
                            Scientific Discoveries
                            Tellus
                            Under the Microscope
            About ARS
                About ARS Home
                            Staff Directory
                            Labs and Research Centers (Map)
                            Headquarter Offices
                            Organizational Chart
                            Employee Services (REE Employees Only)
                            Office of Outreach, Diversity, and Equal Opportunity
            Work With Us
                Work With Us Home
                            ARS Vacancies at USAJOBS
                            Careers at ARS Information
                            Scientific Collaborations
                            Extramural Agreements
                            1890 Faculty Research Sabbatical ProgramSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Title:   Author  item
                                            Rasooly, Reuvenitem
                                            Do, Paulaitem
                                            GRIFFEY, STEPHEN - University Of Californiaitem
                                            VILCHES-MOURE, JOSE - University Of Californiaitem
                                            Friedman, Mendel
  Submitted to: Journal of Agricultural and Food Chemistry
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 7/19/2010
                                    Publication  Date: 7/27/2010
                                    Citation: Rasooly, R., Do, P.M., Griffey, S.M., Vilches-Moure, J.G., Friedman, M. 2010. Ingested Shiga Toxin 2 (Stx2) Causes Histopathological Changes in Kidney, Spleen and Thymus Tissues and Mortality in Mice. Journal of Agricultural and Food Chemistry. (58):9821-9286Interpretive Summary: E. coli serotype O157:H7 produces a family of two major related toxins: Shiga toxin 1 (Stx1) and Shiga toxin 2. Human exposure to these toxins is generally through the consumption of bacterially contaminated red meats, milk and their products. The main objective of this study was to find out whether orally ingested Stx2 can survive the gastrointestinal tract environments of mice, and whether it can be absorbed into the blood circulation, reach and damage the kidney and other tissues, and cause lethality. The results of this study suggest that this may be the case. Our study also implies that there is a need to prevent early contamination of food, as it may be impractical to eliminate the heat-stable toxin from the food by thermal treatment once it has formed.
                                Technical Abstract: The Shiga toxin (Stxs) producing bacterial strain, Escherichia coli O157:H7, colonizes the distal small intestine and the colon, initiating a very broad spectrum of illnesses such as hemolytic-uremic syndrome (HUS) characterized by microangiopathic hemolytic anemia, thrombocytopenia and acute renal failure. It has not been conclusively established as to whether ingestion of Stxs alone without the bacterium poses a potential health risk. To help answer this question, in this study, we fed Shiga toxin 2 (Stx2) directly into the stomachs of mice via gavage. Our data show that in mice, ingestion of Stx2 at a concentration of 50 ug/mouse induces weight loss and kills the mice during 3 to 5 days post-gavage. Additional studies revealed that the toxin retains activity at low pH and that about 1% of the fed toxin is absorbed into the blood circulation, thus lethality by intraperitoneal (IP) injection of Stx2 occurred at much lower doses than by ingestion. Although after 3 days the toxin in blood was not active in a Vero cell assay, detailed histopathological evaluation of stained tissues by light microscopy revealed severe histopathological changes in kidneys, spleen, and thymus, but apparently not in the pancreas, lymph nodes, heart, lungs, trachea, thymus, esophagus, stomach, duodenum, jejunum, ileum, cecum, and colon. The pathological changes in the kidney appeared similar to those seen in humans with HUS. The cited data suggest that (a) most, but not all, of the toxin is inactivated in the digestive tract; (b) part of the oral ingested toxin is absorbed from digestive tract into the circulation; (c), enough active toxin reached susceptible organs to induce lethality; (d) lethality by IP injection of Stx2 occurred at much lower doses than by ingestion; and (e) Stx2 in the absence of toxin-producing bacteria can be harmful to mice. The results may be clinically relevant for food safety because we also found that heat treatments (pasteurization) that destroy bacteria did not inactivate the heat resistant toxin produced and secreted by the bacteria. The possible harmful role of Shiga toxin in the human diet is discussed.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov