Investigation of virulence genes upregulated in coinfection between P. aeruginosa and other species

Summary

Identify the set of genes diffrentially expressed when P. aeruginosa is grown in coculture with three other infecting species. Select genes with virulence/persistence characteristics and delete them. Test effects of gene loss in vitro and in vivo against wildtype.

Supervisor(s)

Dr Jim Manos

Research Location

Camperdown - Central Clinical School

Program Type

Masters/PHD

Synopsis

P. aeruginosa is an opportunistic bacterium that out-competes other species such as Haemophilus influenzae, Staphylococcus aureus and Burkholderia cenocepacia in CF lung, becoming dominant and difficult to eradicate.Little is known about the genetic characteristics that enable P. aeruginosa to out-compete other species and dominate the CF lung. How and why P. aeruginosa gains this dominance needs urgent investigation because i) increasing P. aeruginosa antibiotic resistance, leading to fewer antibiotic options for patient treatment ii) Identifying the gene effects of P. aeruginosa on other species will uncover novel gene targets for therapy. The student will initially have three target genes from previous studies to mutagenise. They will use coculture with either of Staphylococcus aureus, Haemophilus influenzae or Burkholderia cenocepacia to identify and characterise other genes/proteins differentially expressed (DE) by P. aeruginosa Australian Epidemic Strain-1 (AES-1). Data from co and monoculture will be used to generate a profile of gene and protein expression, and mutants in a further AES-1 genes will be made and used in in vitro and in vivo experiments to decide the deleted gene's significance to AES-1 growth.

Specific aims:

  1. Delete separately pelABCDE, pyrC and estA in P. aeruginosa PA14 and determine the in vitro and in vivo effects on the defined mutants.
  2. Conduct co-infection studies with S. aureus, B. cenocepacia or H. influenzae to identify genes/proteins with dominance or persistence functions that are significantly DE in common.
  3. Delete up to six candidate genes and determine the in vitro (cell line)and in vivo (C57Bl/6 mouse model) effects of the defined mutants. 
Outcomes:
Identification of genes facilitating P. aeruginosa dominance of mixed infections. These genes constitute therapeutic targets for future patient treatment through:
  • Identification and use of compounds inhibiting their expression.
  • As a diagnostic screening tool where patients are tested for P. aeruginosa strains expressing these genes and quickly treated.

Additional Information

Co-supervisor: Ian Paulsen

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Keywords

Coinfection of biofilms, Changes in gene expression, Synergistic effects, Dominant behaviour by P. aeruginosa

Opportunity ID

The opportunity ID for this research opportunity is: 233

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