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Physiological Basis for Predator Escape in Salmonella

Butela, Kristen A (2011) Physiological Basis for Predator Escape in Salmonella. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Salmonella enterica, a major causative agent of gastrointestinal illness, exhibits a host-specific pattern of infection, with certain serovars predominantly infecting particular hosts. Extensive variation is observed at the Salmonella rfb locus, which makes up serovar-defining O-antigen. Unlike other pathogens, this diversity cannot be explained by selective pressure from the host immune system. Here, I implicate the O-antigen to the physiological basis for escape from protozoan predators. These predators have differential feeding preferences on Salmonella and may be responsible for maintaining O-antigen diversity, controlling which serovars are able to survive predation to potentially cause disease. I demonstrated that the O-antigen plays a strong role in mediating predator escape and uncovered a trade-off that may exist between O-antigen identity and chain length regulation in response to the dual selective pressures of evading host intestinal predators and successful interaction with the host immune system. To complete these experiments, I developed two new techniques: a) genetic manipulation of non-Typhimurium Salmonella and b) multicolor flow cytometry for assessment of microbes in natural, complex environments. These results link variation at virulence loci to environmental selective pressures other than the host immune system and provide an explanation for the role of the rfb locus in the fragmented speciation process in Salmonella.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Butela, Kristen
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairLawrence, Jeffreyjlawrenc@pitt.eduJLAWRENC
Committee MemberHatfull, Grahamgfh@pitt.eduGFH
Committee MemberCarroll,
Committee MemberKalisz, Susankalisz@pitt.eduKALISZ
Committee MemberOke, Valerievoke@pitt.eduVOKE
Date: 16 September 2011
Date Type: Completion
Defense Date: 14 June 2011
Approval Date: 16 September 2011
Submission Date: 9 August 2011
Access Restriction: 5 year -- Restrict access to University of Pittsburgh for a period of 5 years.
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Biological Sciences
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: antigenic diversity; microbial genome evolution; protozoan predation; Salmonella enterica
Other ID:, etd-08092011-041207
Date Deposited: 10 Nov 2011 19:58
Last Modified: 15 Nov 2016 13:48


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