Virulence regulation in Bordetella pertussis

Abstract

For several years, Bordetella pertussis, the etiological agent of whooping cough, has been the subject of intensive investigations with the aim of developing new vaccines. These studies have revealed much about the complex interactions between the invading pathogen and its eukaryotic host. The different stages of infection with B. pertussis include the adherence to host cells, the colonization of the host tissue and possibly invasion of epithelial cells. Frequently, pathogenic bacteria have to encounter variable environmental conditions, each of them requiring the expression of specific factors at the right time. The coordination of the expression of the relevant factors according to changes in the environment is guaranteed by the unification of most of the virulence related genes into regulons. In the case of B. pertussis, the control of the virulence regulon is mediated by the bvg locus, which codes for a two-component regulatory system. Recent results demonstrate that regulatory factor(s) in addition to the the two-component system are required for expression of some of the virulence factors such as pertussis toxin and adenylate cyclase toxin. This suggests that the virulence associated factors may be expressed differentially during infection, although they are regulated coordinately on the top level of control.