Demonstration of differential virulence gene promoter activation in vivo in Bordetella pertussis using RIVET

• Published in: Molecular microbiology 2005-02, Vol.55 (3), p.788-798
• Main Authors: Veal‐Carr, Wendy L., Stibitz, Scott
• Format: Article
• Language: English
• Subjects: Animals; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Biological and medical sciences; Bordetella pertussis; Bordetella pertussis - genetics; Bordetella pertussis - growth & development; Bordetella pertussis - metabolism; Bordetella pertussis - pathogenicity; Comparative analysis; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Regulation, Bacterial; Genes; Mice; Mice, Inbred BALB C; Microbiology; Miscellaneous; Promoter Regions, Genetic; Recombinases - metabolism; Signal Transduction; Transcription Factors - genetics; Transcription Factors - metabolism; Transcription, Genetic; Virulence - genetics; Virulence Factors, Bordetella - genetics; Virulence Factors, Bordetella - metabolism; Whooping cough; Whooping Cough - microbiology
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/j.1365-2958.2004.04418.x

Summary Bordetella pertussis, the etiologic agent of whooping cough, causes disease by employing an array of virulence factors controlled by the BvgA–BvgS two‐component signal transduction system. Regulation by this system has been extensively characterized in vitro, where bvg‐activated genes are repressed in a process known as phenotypic modulation. Differential regulation of these genes by the response regulator BvgA results in promoters that are activated early, middle, or late after being released from modulation. However, the in vivo environmental signal and regulation pattern has not been described. In order to investigate BvgAS‐mediated regulation of B. pertussis virulence factors in vivo using the mouse aerosol challenge model, we have adapted the recombinase‐based in vivo technology (RIVET) system for use in B. pertussis. We have demonstrated that these strains show resolution during in vitro growth under non‐modulating conditions. In addition, we have demonstrated that modulating strains by growth on media containing MgSO4 does not affect virulence in the mouse aerosol challenge model. We have therefore used the RIVET system to reveal the time‐course of gene expression in vivo for selected B. pertussis virulence factors (cya, fha, prn and ptx). Our data indicate that this method can be effectively used to monitor and compare in vivo and in vitro gene expression in B. pertussis, and that temporal regulation patterns previously observed in vitro are mirrored in vivo.