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dc.contributor.authorScully, Lisa R.en_US
dc.date.accessioned2009-05-28T16:39:37Z
dc.date.available2009-05-28T16:39:37Z
dc.date.issued2007-05-28T16:39:37Z
dc.identifier.urihttp://hdl.handle.net/10464/1452
dc.description.abstractTo study emerging diseases, I employed a model pathogen-host system involving infections of insect larvae with the opportunistic fungus Aspergillus flavus, providing insight into three mechanisms ofpathogen evolution namely de novo mutation, genome decay, and virulence factoracquisition In Chapter 2 as a foundational experiment, A. flavus was serially propagated through insects to study the evolution of an opportunistic pathogen during repeated exposure to a single host. While A. flavus displayed de novo phenotypic alterations, namely decreased saprobic capacity, analysis of genotypic variation in Chapter 3 signified a host-imposed bottleneck on the pathogen population, emphasizing the host's role in shaping pathogen population structure. Described in Chapter 4, the serial passage scheme enabled the isolation of an A. flavus cysteine/methionine auxotroph with characteristics reminiscent of an obligate insect pathogen, suggesting that lost biosynthetic capacity may restrict host range based on nutrient availability and provide selection pressure for further evolution. As outlined in Chapter 6, cysteine/methionine auxotrophy had the pleiotrophic effect of increasing virulence factor production, affording the slow-growing auxotroph with a modified pathogenic strategy such that virulence was not reduced. Moreover in Chapter 7, transformation with a virulence factor from a facultative insect pathogen failed to increase virulence, demonstrating the necessity of an appropriate genetic background for virulence factor acquisition to instigate pathogen evolution.en_US
dc.language.isoengen_US
dc.publisherBrock Universityen_US
dc.subjectHost-parasite relationships.en_US
dc.subjectViruses--Evolution.en_US
dc.titleAspergillus flavus infections in Galleria mellonella : a pathogen-host model system for the study of emerging diseasesen_US
dc.typeElectronic Thesis or Dissertationen_US
dc.degree.namePh.D. Biological Sciencesen_US
dc.degree.levelDoctoralen_US
dc.contributor.departmentDepartment of Biological Sciencesen_US
dc.degree.disciplineFaculty of Mathematics and Scienceen_US


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