The RNA Chaperone Hfq Is Required for Virulence of Bordetella pertussis

Abstract

ABSTRACTBordetella pertussisis a Gram-negative pathogen causing the human respiratory disease called pertussis or whooping cough. Here we examined the role of the RNA chaperone Hfq inB. pertussisvirulence. Hfq mediates interactions between small regulatory RNAs and their mRNA targets and thus plays an important role in posttranscriptional regulation of many cellular processes in bacteria, including production of virulence factors. We characterized anhfqdeletion mutant (Δhfq) ofB. pertussis18323 and show that the Δhfqstrain produces decreased amounts of the adenylate cyclase toxin that plays a central role inB. pertussisvirulence. Production of pertussis toxin and filamentous hemagglutinin was affected to a lesser extent.In vitro, the ability of the Δhfqstrain to survive within macrophages was significantly reduced compared to that of the wild-type (wt) strain. The virulence of the Δhfqstrain in the mouse respiratory model of infection was attenuated, with its capacity to colonize mouse lungs being strongly reduced and its 50% lethal dose value being increased by one order of magnitude over that of the wt strain. In mixed-infection experiments, the Δhfqstrain was then clearly outcompeted by the wt strain. This requirement for Hfq suggests involvement of small noncoding RNA regulation inB. pertussisvirulence.