Evaluation of the infection-relevant role of small RNA-based regulatory systems in the opportunistic pathogen Pseudomonas aeruginosa

Pseudomonas aeruginosa is an important opportunistic pathogen in immune-compromised and cystic fibrosis patients. We have performed a comparative small RNA (sRNA) profiling via deep-sequencing of P. aeruginosa PAO1 and PA14 strains (1) which share the same host range but differ in pathogenicity. We now aim at identifying infection-relevant sRNA-based regulatory systems. To this end, we are focusing on a short list of 8 validated sRNAs which showed, at preliminary screenings, potential virulence hallmarks such as: specific expression in PA14 or PAO1; responsiveness to infection-relevant host stimuli (e.g. oxygen availability, temperature shift) or invasion signals (e.g. quorum sensing). Our approach is to generate sRNA deletion mutants and test them for i) canonical virulence phenotype(s); ii) ability to invade human respiratory epithelial cells and stimulate an immune response; iii) airways infection in both acute and chronic murine models. The above tests are accompanied by in silico, genetic and transcriptomics-based screenings for the genome-wide search of sRNAs target genes. 1. Ferrara S et al. (2012). PLoS One 7: e36553.