Differential regulation of Bordetella pertussis virulence factors.

Bordetella pertussis, the causative agent of whooping cough, regulates its virulence factors coordinately according to environmental parameters such as temperature and certain chemicals. A regulatory locus has been characterized which is essential for this regulation. This bvg locus codes for a two-component regulatory system composed of the sensor protein BvgS and the transcriptional activator protein BvgA. It has been shown that the BvgA and BvgS proteins are sufficient for the transcriptional regulation of some virulence factors such as the filamentous haemagglutinin (FHA) involved in adhesion. The recent identification of new regulatory mutants demonstrates that the regulation of some virulence factors such as the pertussis toxin (PTX) and the adenylate cyclase toxin (CYA) is more complex and involves additional regulatory factor(s). This finding suggests that the regulation of the various virulence factors is coordinated at the highest level of regulation, but there may be differences in the fine regulation of some of the factors such as the adhesins and the toxins.