• Login
    View Item 
    •   UMB Digital Archive
    • School, Graduate
    • Theses and Dissertations All Schools
    • View Item
    •   UMB Digital Archive
    • School, Graduate
    • Theses and Dissertations All Schools
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of UMB Digital ArchiveCommunitiesPublication DateAuthorsTitlesSubjectsThis CollectionPublication DateAuthorsTitlesSubjects

    My Account

    LoginRegister

    Statistics

    Display statistics

    Characterization of autotransporters of the Surface cell antigen (Sca) family in Rickettsia typhi

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    Sears_umaryland_0373D_10248.pdf
    Size:
    8.795Mb
    Format:
    PDF
    Download
    Author
    Sears, Khandra T.
    Advisor
    Azad, Abdu F.
    Date
    2011
    Type
    dissertation
    
    Metadata
    Show full item record
    Abstract
    Members of the genus Rickettsia, a group of obligate intracellular α-proteobacteria, include the causative agents of typhus and spotted fevers. Murine typhus is a reemerging infectious disease with endemic foci established worldwide and little is understood about how its agent, R. typhi, infects its mammalian and insect hosts. Due to the genetic intractability of rickettsiae, few factors have been identified as being required for their pathogenesis; however, it is well established that rickettsial outer membrane proteins A and B (OmpA and OmpB) are required for invasion of mammalian host cells. Both proteins are autotransporters (type V secretion system) that belong to the surface cell antigen (Sca) family in rickettsia. R. typhi, the agent of murine typhus, has five scas including OmpB (Sca5). Considering the importance of OmpB during infection of mammalian hosts, characterization of other Sca family members may yield some insight into the pathogenesis of murine typhus. Each Sca protein was expressed during in vitro infection in mouse fibroblasts and in vivo infections in spleens from infected Sprague-Dawley rats (a model reservoir) and Ctenocephalides felis cat fleas (a common vector). All Scas were detected on the bacterial surface by immunogold electron microscopy. Subsequent investigations focused on Sca2, which is predicted to mediate adhesion, invasion, bacterial aggregation and collagen binding. Heterologous expression of Sca2 mediated autoaggregation and biomass accumulation comparable to that of the Escherichia coli autotransporter involved in diffuse adherence-1. Treatment of rickettsiae with anti-Sca2 serum decreased rickettsial burden in primary human umbilical vein endothelial cells and invasion of mouse fibroblasts. Additionally, E. coli expressing Sca2, which contains a von Willebrand factor type A collagen binding domain, bound collagen types I, III, IV and VI. This finding has implications for subversion of the inflammatory response-associated vasculitis observed in rickettsial infections. Sca proteins may be crucial to the invasion process and/or dampening inflammation associated with rickettsial infection of endothelial cells. The work presented here is evidence that rickettsial surface proteins mediate rickettsial interactions lending credence towards efforts to characterize the remaining Scas of R. typhi.
    Description
    University of Maryland in Baltimore. Molecular Microbiology and Immunology. Ph.D. 2011
    Keyword
    von Willebrand factor type A domain
    Antigens, Surface
    Rickettsia typhi
    Identifier to cite or link to this item
    http://hdl.handle.net/10713/767
    Collections
    Theses and Dissertations All Schools
    Theses and Dissertations School of Medicine

    entitlement

     
    DSpace software (copyright © 2002 - 2023)  DuraSpace
    Quick Guide | Policies | Contact Us | UMB Health Sciences & Human Services Library
    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.