School of Infection & Immunity

Dr Rhiannon Lyon 

Title: Discovery and characterisation of novel phage defence systems in Pseudomonas aeruginosa

Synopsis:

Bacteria use a wide range of anti-phage defence mechanisms to protect against phage infection. In recent years, the number of identified systems has expanded rapidly, with over 200 novel defences discovered since 2018. This accelerated rate of discovery has been driven by bioinformatic analyses based on the clustering of these systems in ‘defence islands’ and ‘guilt by association’. Around 160 of these novel defence systems are seen in Pseudomonas aeruginosa, an important opportunistic pathogen and a target for the development of phage therapy. In this work, we identify and experimentally validate novel candidate anti-phage systems in P. aeruginosa. These systems were discovered within novel defence hotspots recently characterised by our lab in Pseudomonas pathogenicity island 1. Using knock-in mutants and a diverse phage panel, we assess their contribution to phage resistance and begin to define their modes of action. Our findings indicate that these systems encompass distinct mechanistic classes, including responses consistent with abortive infection, and illustrate a trend of known anti-phage domains being repurposed in new genetic contexts to generate novel defence strategies. Together, this work expands the known repertoire of anti-phage systems in P. aeruginosa and highlights the modularity and evolutionary flexibility of bacterial defence.

Bio:

Rhiannon completed her undergraduate and integrated master's degree in biochemistry and molecular biology at the University of Sheffield. She completed her PhD at the University of Warwick in the Chen group looking at the impact of membrane lipid remodelling on phage therapy in Pseudomonas aeruginosa. Between 2024-2025 she completed a short post doc looking for phages targeting methanotrophs at the University of Birmingham. In September 2025 she joined the Mariano lab as a post doc investigating anti-phage systems in Pseudomonas aeruginosa.

First published: 16 September 2026

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