RT Journal Article SR Electronic(1) A1 Harmer, Christopher A1 Alnassafi, Khaled A1 Hu, Honghuah A1 Elkins, Mark A1 Bye, Peter A1 Rose, Barbara A1 Cordwell, Stuart A1 Triccas, James A. A1 Harbour, Colin A1 Manos, JimYR 2013 T1 Modulation of gene expression by Pseudomonas aeruginosa during chronic infection in the adult cystic fibrosis lung JF Microbiology, VO 159 IS Pt_11 SP 2354 OP 2363 DO https://doi.org/10.1099/mic.0.066985-0 PB Microbiology Society, SN 1465-2080, AB Chronic Pseudomonas aeruginosa infection is the leading cause of morbidity and mortality in cystic fibrosis (CF) patients. P. aeruginosa isolates undergo significant transcriptomic and proteomic modulation as they adapt to the niche environment of the CF lung and the host defences. This study characterized the in vitro virulence of isogenic strain pairs of P. aeruginosa epidemic or frequent clonal complexes (FCCs) and non-epidemic or infrequent clonal complexes (IFCCs) that were collected 5–8 years apart from five chronically infected adult CF patients. Strains showed a significant decrease in virulence over the course of chronic infection using a Caenorhabditis elegans slow-killing assay and in phenotypic tests for important virulence factors. This decrease in virulence correlated with numerous differentially expressed genes such as oprG, lasB, rsaL and lecB. Microarray analysis identified a large genomic island deletion in the IFCC strain pair that included type three secretion system effector and fimbrial subunit genes. This study presents novel in vitro data to examine the transcriptomic profiles of sequentially collected P. aeruginosa from CF adults. The genes with virulence-related functions identified here present potential targets for new therapies and vaccines against FCCs and IFCCs., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.066985-0