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Temperate phages both mediate and drive adaptive evolution in pathogen biofilms

Davies, E, James, C, Williams, D, O'Brien, S, Fothergill, J, Haldenby, S, Paterson, S, Winstanley, C and Brockhurst, M 2016, 'Temperate phages both mediate and drive adaptive evolution in pathogen biofilms' , Proceedings of the National Academy of Sciences of the United States of America (PNAS), 113 (29) , pp. 8266-8271.

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Abstract

Temperate phages drive genomic diversification in bacterial pathogens. Phage-derived sequences are more common in pathogenic than non-pathogenic taxa, and are associated with changes in pathogen virulence. High abundance and mobilisation of temperate phages within hosts suggests that temperate phages could promote within-host evolution of bacterial pathogens. However,their role in pathogen evolution has not been experimentally tested. We experimentally evolved replicate populations of Pseudomonas aeruginosa with or without a community of three temperate phages active in cystic fibrosis (CF) lung infections, including the transposable phage, ɸ4, which is closely related to phage D3112. Populations grew as free-floating biofilms in artificial sputum medium, mimicking sputum of CF lungs where P. aeruginosa is an important pathogen and undergoes evolutionary adaptation and diversification during chronic infection. While bacterial populations adapted to the biofilm environment in both treatments, population genomic analysis revealed that phages altered both the trajectory and mode of evolution. Populations evolving with phages exhibited a greater degree of parallel evolution and faster selective sweeps than populations without phages. Phage ɸ4, integrated randomly into the bacterial chromosome but integrations into motility-associated genes and regulators of quorum sensing systems essential for virulence were selected in parallel, strongly suggesting that these insertional inactivation mutations were adaptive. Temperate phages, and in particular transposable phages, are therefore likely to facilitate adaptive evolution of bacterial pathogens within hosts.

Item Type: Article
Schools: Schools > School of Environment and Life Sciences
Journal or Publication Title: Proceedings of the National Academy of Sciences of the United States of America (PNAS)
Publisher: National Academy of Sciences
ISSN: 1091-6490
Related URLs:
Funders: The Wellcome Trust, The Medical Research Council, Institute of Global Health, University of Liverpool
Depositing User: Dr Chloe James
Date Deposited: 02 Jun 2016 09:54
Last Modified: 20 Sep 2016 09:50
URI: http://usir.salford.ac.uk/id/eprint/39088

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