Micobial Pathogenesis and Immunity Group

Lab head: A/Prof Jamie Triccas
Location: Blackburn Building The University of Sydney, Camperdown Campus

Defining the interaction of Pseudomonas aeruginosa with components of the host immune response

Primary supervisor: James Triccas

Infection with Pseudomonas aeruginosa is the major cause of mortality in people living with the genetic disorder cystic fibrosis (CF). CF occurs in 1 out of 2500 Caucasians, and is characterised by the production of thick, static lung mucus. Unlike other bacterial pathogens that can be easily cleared from the CF lung by antibiotic therapy, P. aeruginosa persists in the mucus and is likely to exacerbate lung inflammation during chronic infection. Further, P. aeruginosa is a major cause of hospital-acquired infection, in particular burns and wounds.

Despite the importance of his pathogen in CF and other infections, the immune response against clinical PP. aeruginosa isolates has been poorly studied. We have access to clinical strains of P. aeruginosa isolated from patients with CF, including ‘persistent’ strains that chronically infect patients. How these strains interact with the host immune response and potentially modify immunity to promote persistence is unknown.

In this project we will examine in detail the immunity generated by P. aeruginosa in a mouse model of infection. By using both persistent and non-persistent P. aeruginosa clones we will determine which immune parameters are associated with chronic infection. To do this, recombinant P. aeruginosa strains will be developed that express fluorescent markers (e.g. mCherry) as well as the model ovalbumin protein (OVA) and a well characterized CD4 T cell antigen (Ag85B). Both CD4⁺ and CD8⁺ transgenic T cell receptor mice that recognise either the OVA or Ag85B proteins are available in the laboratory. By using multi-parameter flow cytometry and adoptive T cell transfer systems, we will examine the kinetics of T cell activation, migratory patterns of activated T cells and generation of T cell memory after P. aeruginosa infection. We will also determine the influence of infection on the expansion and activation of innate cells (e.g. macrophages, dendritic cells, neutrophils) as well as the release of inflammatory cytokines. We will be particularly interested in comparing responses after infection with persistent and non-persistent strains, to determine if certain immune parameters correlate with strain persistence and virulence. In parallel will also use advanced miscopy techniques to examine the early interaction of the strains with host cells. This will allow us to determine how the interaction of P. aeruginosa with host cells impacts on the subsequent generation of T cell immunity.

This project will give the student experience in molecular biology techniques, animal handling, infection strategies and various immunological techniques (tissue culture, assays of T cell activation including ELISPOT, multi-parameter flow cytometry).

Discipline: Infectious diseases and Immunology
Co-supervisors: Jim Manos
Keywords: Infection and immunity, Cystic fibrosis, Pseudomonas aeruginosa
Contact: Email James Triccas