Carbohydrate Mediated Regulation of Expression of Pathogenicity Determinants in Listeria Monocytogenes

  • E. J. McCulloch

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)


INTRODUCTION: Listeria monocytogenes is a Gram-positive, facultative intracellular pathogen which causes listeriosis, an important food-borne infection, with a high fatality rate. Temperature and growth media constituents have been previously shown to repress virulence factor expression in L. monocytogenes but the mechanisms of control surrounding this virulence factor repression are poorly understood.

METHODS: Using both functional and biochemical assays to measure virulence factors, particularly listeriolysin, and molecular techniques such as real-time PCR and Northern blot analysis to analyse the transcription of key virulence genes, particularly hlyA, in the presence or absence of carbohydrates it was hoped a better understanding of virulence factor control could elucidated.

RESULTS: The results showed that while virulence factors themselves were clearly repressed in the presence of certain carbohydrates substantial transcription of the genes was found under any growth condition.

CONCLUSIONS: These findings suggest that in addition to PrfA control there are subtle post-translational mechanisms in place regulating virulence factor expression in L. monocytogenes. The existence of these mechanisms is demonstrated here but they still remain largely undefined.
Date of Award2008
Original languageEnglish
Awarding Institution
  • Glasgow Caledonian University
SupervisorAlastair Sutherland (Supervisor)

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