Effect of Active Prophage on the Virulence of Pseudomonas aeruginosa

SPARC 2022 Poster Number 8

The Liverpool epidemic strain (LES) of the bacterium Pseudomonas aeruginosa is a key opportunistic pathogen and major cause of death in Cystic Fibrosis (CF) patients. This is due to the bacterium becoming established in patient’s lungs and forming hard to remove communities called biofilms. These biofilms are incredibly hard to treat as the bacteria are surrounded by a protective polysaccharide matrix which enables tolerance and resistance development against antibiotics.

The success of the LES strain is thought to be influenced by several prophages present in its genome and have been associated with increased competitiveness in the CF lung. Prophages are the integrated genomes of a type of virus called bacteriophages that can infect and destroy their host bacteria by bursting out of them or, as in this case, become part of their hosts DNA and provide fitness advantages. Active phages are very common in the CF lung and infecting Pseudomonas aeruginosa strains commonly have many prophages integrated into their genome, but little is known about the co-operative interactions between the two. This project investigates the relationship between three active phages of LES and the model bacterial host strain PA01, hopefully aiding the development of CF treatments. Experiments revealed that the prophages affect the growth rate of their bacterial host differently depending on the conditions. Furthermore, infection model experiments indicated that prophage carriage reduces the severity of disease when challenging the wax moth larvae Galleria mellonella. These data suggest that the LES prophages may contribute to adaptation for longer survival.