Distinct virulence ranges for infection of mice by Bordetella pertussis revealed by engineering of the sensor-kinase BvgS

Abstract

The whooping cough agent Bordetella pertussis coordinately regulates the expression of its virulence factors with the two-component system BvgAS. In laboratory conditions, specific chemical modulators are used to trigger phenotypic modulation of B. pertussis from its default virulent Bvg+ phase to avirulent Bvg- or intermediate Bvgi phases, in which no virulence factors or only a subset of them are produced, respectively. Whether phenotypic modulation occurs in the host remains unknown. In this work, recombinant B. pertussis strains harboring BvgS variants were tested in a mouse model of infection and analyzed using transcriptomic approaches. Recombinant BP-BvgΔ65, which is in the Bvgi phase by default and can be up-modulated to the Bvg+ phase in vitro, could colonize the mouse nose but was rapidly cleared from the lungs, while Bvg+-phase strains colonized both organs for up to four weeks. These results indicated that phenotypic modulation, which might have restored the full virulence capability of BP-BvgΔ65, does not occur in mice or is temporally or spatially restricted and has no effect in those conditions. Transcriptomic analyses of this and other recombinant Bvgi and Bvg+-phase strains revealed that two distinct ranges of virulence gene expression allow colonization of the mouse nose and lungs, respectively. We also showed that a recombinant strain expressing moderately lower levels of the virulence genes than its wild type parent was as efficient at colonizing both organs. Altogether, genetic modifications of BvgS generate a range of phenotypic phases, which are useful tools to decipher host-pathogen interactions.

Streamlined copper defenses make Bordetella pertussis reliant on custom-made operon

“…For RNA extractions, the cultures were stopped by adding 2 mL of a mixture of phenol:ethanol (5:95) to 8 mL of bacterial suspensions. Bacteria were pelleted, and total RNA was extracted with TriReagent (InVitrogen) 55 . Genomic DNA was removed by a DNAse I treatment (Sigma Aldrich).…”

Analysis of the In Vivo Transcriptome of Bordetella pertussis during Infection of Mice

“…Furthermore, Lesne et al teased out the distinct virulence ranges of B. pertussis governed by this system during murine respiratory tract infection using bvgS mutants (27). After identifying the unique infection profiles of each strain, they performed in vitro RNA-seq to characterize the effects of the mutations in bvgS and how they affect downstream gene expression (27).…”

“…pertussis governed by this system during murine respiratory tract infection using bvgS mutants (27). After identifying the unique infection profiles of each strain, they performed in vitro RNA-seq to characterize the effects of the mutations in bvgS and how they affect downstream gene expression (27). While in vitro RNA-seq analysis provides important insights about regulation of virulence, only one study has been performed to determine what B.…”

Production of Highly Active Recombinant Dermonecrotic Toxin of Bordetella Pertussis

“…However, B. pertussis is an exclusively human pathogen and a subtle phenotype of a dnt mutant would likely not be revealed in the widely used mouse model of transient lung colonization by B. pertussis, which does not adequately reproduce the pathophysiology of human nasopharynx infection. Therefore, the role of DNT in the capacity of B. pertussis to colonize the nasal cavity of mice and primates needs to be addressed [33,34].…”