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
 Food Safety and Intervention Technologies Research: Wyndmoor, PA
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                People

                    Staff Listing
                                    Careers


        


                    About ERRC
                        Greetings from the Director
                                    Directions/Lodging
                                    History and Accomplishments
                    Our Work
                        Biomass Pyrolysis Research
                                    IPMP 2013
                                    IPMP Dynamic Prediction
                                    IPMP Global Fit
                                    Pathogen Modeling Program (PMP)
                                    Predictive Microbiology Information Portal (PMIP)
                                    PoultryFARMSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Northeast Area Wyndmoor, Pennsylvania Eastern Regional Research Center Food Safety and Intervention Technologies Research 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
                                            WHITAKER, BRIAN - University Of Delawareitem
                                            PARENT, MICHELLE - University Of Delawareitem
                                            AOIFE, BOYD - National University Of Irelanditem
                                            Richards, Garyitem
                                            BOYD, FIDELMA - University Of Delaware
  Submitted to: Infection and Immunity
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 3/15/2012
                                    Publication  Date: 5/21/2012
                                    Citation: Whitaker, B.W., Parent, M.A., Aoife, B., Richards, G.P., Boyd, F.E. 2012. Vibrio parahaemolyticus ToxRS regulator is required for stress tolerance and colonization in a novel orogastric streptomycin-induced adult murine model. Infection and Immunity. 80:1834-1845.Interpretive Summary: The leading cause of seafood-related bacterial illness in the United States is a naturally occurring marine bacterium known as Vibrio parahaemolyticus.  The infectivity of V. parahaemolyticus is related to specific genes, such as the toxRS gene, which produce proteins known as ToxR and ToxS.  We evaluated the influence of the toxRS gene on the ability of V. parahaemolyticus to survive stresses, like acid, bile salts, and chemical stress, as would be encountered within the stomach of an infected individual.  To accomplish this, a mutant strain of V. parahaemolyticus lacking the toxRS gene was designed and compared with the normal strain containing the toxRS gene.  We determined that the ToxR and ToxS proteins regulate an outer membrane protein referred to as OmpU, making the vibrios more tolerant of stresses, whereas mutants lacking the toxRS gene were less tolerant of a stressful environment.  All V. parahemolyticus used in this study were resistant to the antibiotic streptomycin.  Streptomycin resistance allowed us to develop a new model of infection using streptomycin-treated, adult mice.  Antibiotic-treated mice experienced a persistent colonization of their intestinal tract by V. parahaemolyticus which contained the toxRS gene, but not when the toxRS gene was missing. This study demonstrated the usefulness of this adult, mouse model in monitoring the effects of the toxRS gene on bacterial invasiveness and will facilitate an evaluation of other genes that may be associated with vibrio invasiveness. Overall, we demonstrated that the toxRS gene is an important regulator of the stress response of V. parahaemolyticus and that the adult mouse model is a valuable new tool for studies to understand bacterial and host factors crucial for bacterial colonization of the gastrointestinal tract.
                                Technical Abstract: Vibrio parahaemolyticus, a marine bacterium, is the causative agent of gastroenteritis associated with the consumption of seafood.  It contains a homologue of the toxRS operon that in V. cholerae is the key regulator of virulence gene expression.  We examined a non-polar mutation in toxRS to determine the role of these genes in V. parahaemolyticus RIMD2210633, a O3:K6 isolate, and showed that the toxRS deletion mutant compared to the wild-type was significantly more sensitive to acid, bile salts and sodium dodecyl sulfate stresses.  We demonstrated that ToxRS is a positive regulator of ompU expression and that complementation of the toxRS deletion mutant with ompU restored stress tolerance.  Furthermore, we showed that ToxRS regulated type III secretion system genes in chromosome I independent of OmpU regulation.  We examined the effect of the toxRS deletion mutant in vivo using a new orogastric adult murine model of colonization.  We demonstrated that streptomycin-treated C57BL/6 adult mice experienced prolonged intestinal colonization along the entire intestinal tract by the streptomycin-resistant V. parahaemolyticus.  In contrast, no colonization occurred in non-streptomycin-treated mice.  A competition assay between the toxRS mutant and wild-type V. parahaemolyticus marked with the beta-galactosidase gene lacZ demonstrated that the toxRS deletion mutant was defective in colonization compared to wild-type. This defect was rescued by ectopically expressing ompU.  Thus, the defect in stress tolerance and colonization in the toxRS mutant was solely due to OmpU.  To our knowledge, the orogastric adult murine model reported here is the first showing sustained intestinal colonization by V. parahaemolyticus.


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