Abstract
<jats:p> With the rise of antimicrobial resistance, anti-virulence therapeutics are a viable alternative to circumvent resistance pressures. Hypothetical genes and proteins are an under-studied source of potential virulence factor targets. We performed bioinformatic analyses to identify conserved hypothetical genes enriched in pathogenic <jats:italic>Pseudomonas aeruginosa</jats:italic> but not in non-pathogenic strains. This analysis identified an atypical BlaIR system, which we named <jats:italic>pvmSR</jats:italic> , that regulated <jats:italic>P. aeruginosa</jats:italic> virulence in a <jats:italic>Caenorhabditis elegans</jats:italic> infection model. This is in contrast with the typical BlaIR system from <jats:italic>Staphylococcus aureus</jats:italic> , which regulates resistance to β-lactam antibiotics. The <jats:italic>ΔpvmSR</jats:italic> mutant showed reduced virulence in a <jats:italic>C. elegans</jats:italic> slow-killing assay. To understand how PvmSR regulated virulence <jats:italic>in vivo</jats:italic> , we performed dual RNA-seq to analyze transcriptomic changes in both <jats:italic>C. elegans</jats:italic> and <jats:italic>P. aeruginosa</jats:italic> . We found that <jats:italic>C. elegans</jats:italic> responded to <jats:italic>P. aeruginosa ΔpvmSR</jats:italic> infection by decreasing expression of lysosome and phagocytosis pathways. In <jats:italic>P. aeruginosa ΔpvmSR,</jats:italic> we observed decreased gene expression of several known virulence factors including the hydrogen cyanide synthase, <jats:italic>hcnC</jats:italic> , and heparinase, <jats:italic>hepP</jats:italic> . Additionally, we observed dysregulation in genes important for quorum sensing and biofilm formation. Collectively, our findings indicated that PvmSR contributed to virulence regulation and may serve as a potential anti-virulence target. </jats:p>