Identification and characterization of infection-associated plasmids in Borrelia burgdorferi B31 /
Bacterial extrachromosomal elements or plasmids usually encode virulence determinants that give bacteria an advantage during host-pathogen interactions. Borrelia burgdorferi carries several plasmids in its genome, and although previous reports suggested a potential role for these plasmids in infect...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2002.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=765069821&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Bacterial extrachromosomal elements or plasmids usually encode virulence determinants that give bacteria an advantage during host-pathogen interactions. Borrelia burgdorferi carries several plasmids in its genome, and although previous reports suggested a potential role for these plasmids in infectivity, no clear correlation between specific plasmids and infectivity had been established. In order to determine which specific B. burgdorferi plasmids were associated with an infectious phenotype, I used the information provided by the B. burgdorferi genome project coupled with PCR to assess the specific genetic composition of several B. burgdorferi clones. Using this approach I was able to find clones missing one or more plasmids that were subsequently used in infectivity studies. Based on the genetic composition of these clones and their corresponding infectivity phenotype, I was able to establish a correlation between plasmid content with an infectious phenotype. I identified two plasmids, linear plasmid 25 (lp25) and linear plasmid 28-1 (lp28-1) that are required for infectivity in the mouse model of infection. I have further determined that lp25 encodes an essential element that is required for in vivo survival, but the exact identity of this factor is yet to be determined. I also show that lp28-1 is required for persistence but not for dissemination in tissues, as mutants are able to disseminate but are eventually cleared by the adaptive immune response perhaps due to the absence of the antigenic variant, VlsE, encoded in the missing plasmid. My results demonstrate a correlation between the loss of specific plasmids and infectivity in B. burgdorferi strain B31 and that this spirochete, like other pathogenic organisms, carries pathogenic determinants in its plasmid collection that give the bacteria an advantage during the infection process. |
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| Item Description: | Vita. "Major Subject: Medical Sciences". |
| Physical Description: | x, 93 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 81-92). |