title: Lytic activity by temperate phages of Pseudomonas aeruginosa in long-term cystic fibrosis chronic lung infections.
abstract: Pseudomonas aeruginosa is the most common bacterial pathogen infecting the lungs of cystic fibrosis (CF) patients. The transmissible Liverpool epidemic strain (LES) harbours multiple inducible prophages (LESϕ2; LESϕ3; LESϕ4; LESϕ5; and LESϕ6), some of which are known to confer a competitive advantage in an in vivo rat model of chronic lung infection. We used quantitative PCR (Q-PCR) to measure the density and dynamics of all five LES phages in the sputa of 10 LES-infected CF patients over a period of 2 years. In all patients, the densities of free-LES phages were positively correlated with the densities of P. aeruginosa, and total free-phage densities consistently exceeded bacterial host densities 10-100-fold. Further, we observed a negative correlation between the phage-to-bacterium ratio and bacterial density, suggesting a role for lysis by temperate phages in regulation of the bacterial population densities. In 9/10 patients, LESϕ2 and LESϕ4 were the most abundant free phages, which reflects the differential in vitro induction properties of the phages. These data indicate that temperate phages of P. aeruginosa retain lytic activity after prolonged periods of chronic infection in the CF lung, and suggest that temperate phage lysis may contribute to regulation of P. aeruginosa density in vivo.
authors.affiliation: 1] Institute of Infection and Global Health, University of Liverpool, Liverpool, UK [2] School of Environment and Life Sciences, University of Salford, Manchester, UK.
authors.forename: Chloe E
authors.initials: CE
authors.lastname: James
authors.affiliation: Institute of Infection and Global Health, University of Liverpool, Liverpool, UK.
authors.forename: Emily V
authors.initials: EV
authors.lastname: Davies
authors.affiliation: Institute of Infection and Global Health, University of Liverpool, Liverpool, UK.
authors.forename: Joanne L
authors.initials: JL
authors.lastname: Fothergill
authors.affiliation: Liverpool Heart and Chest Hospital, Liverpool, UK.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Walshaw
authors.affiliation: Department of Biology, University of York, York, UK.
authors.forename: Colin M
authors.initials: CM
authors.lastname: Beale
authors.affiliation: Department of Biology, University of York, York, UK.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Brockhurst
authors.affiliation: Institute of Infection and Global Health, University of Liverpool, Liverpool, UK.
authors.forename: Craig
authors.initials: C
authors.lastname: Winstanley
mesh_terms: D000818:Animals; D003165:Complement System Proteins; D003550:Cystic Fibrosis / Q000382:microbiology*; D004195:Disease Models, Animal; D006801:Humans; D008168:Lung / Q000382:microbiology; D016133:Polymerase Chain Reaction; D039002:Prophages; D011552:Pseudomonas Infections / Q000382:microbiology*; D017105:Pseudomonas Phages / Q000502:physiology*; D011550:Pseudomonas aeruginosa / Q000821:virology*; D012141:Respiratory Tract Infections / Q000382:microbiology*; D013183:Sputum / Q000382:microbiology
chemical_list: D003165:Complement System Proteins