CASE BASED REVIEW OF MEDICAL MICROBIOLOGY
Bordetella pertussis
Dr Tadayo Hashimoto M.D.
Professor
Department of Microbiology & Immunology
Why does B. pertussis produce various toxins or virulence factors only when it enters the human host?
- The expression of virulence-related genes is temperature dependent. B. pertussis produces toxins or virulent factors when the environmental temperature is raised to 37°C.
- At 25°C, the membrane associated regulatory protein (BvgS) is inactive as are other genes that encode for virulence factors (Fha, PT, adenyl cyclase).
- At 37°C, BvgS autophosphorylates and activate a cytoplasmic regulatory protein called BvgA by phosphorylation. This activate, directly or indirectly, transcription of BvgS, BgvA, Fha, pili and Act.
- The first step in shifting a culture from 25° to 37°C involves the transcriptional activation of Fha and pilin genes.
- ACT, then, activates pertussis toxin (PT) and adenyl cyclase (Acase) genes.
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