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Bordetella pertussis tracheal cytotoxin
Abstract:
The most consistent pathological feature of pertussis is the selective colonization and subsequent destruction of ciliated cells in the respiratory epithelium. Phase I B. pertussis can reproduce the human respiratory tract cytopathology during in vitro infection of hamster tracheal organ cultures. However, most isolated biologically active components produced by B. pertussis (lymphocytosis-promoting factor, adenylate cyclase, dermonecrotic toxin, etc.) have no apparent cytopathic effect on the respiratory epithelium. We have purified a glycopeptide from the culture supernatant of virulent B. pertussis that mimics completely the ciliated cell pathology characteristic of pertussis (5). Tracheal cytotoxin (TCT) is released during log phase broth culture and consists of 15 amino acid residues as well as two amino sugars. The selective biological activity of TCT has been studied in tracheal organ cultures by light and electron microscopy. A series of pathological changes precedes the eventual extrusion of ciliated cells, while all other epithelial cell types appear ultrastructurally normal. TCT also causes a dose-dependent inhibition of DNA synthesis in cultured hamster trachea epithelial cells, providing a quantitative bioassay to monitor TCT activity during purification steps. Previously, TCT could be completely purified from oxidized glutathione (a major contaminant from the culture medium) only by high-voltage paper electrophoresis, a procedure not well suited for large scale work. We have now substituted a final column chromatography step that separates TCT from oxidized glutathione and other contaminating peptides. This change and other preparative scale adaptations now allow us to purify 150-250 nmol of biologically active TCT from one liter of culture supernatant (3-4 X 10(13) bacteria), a ten-fold increase over our previous batch size with no increase in processing time.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Researchers identified Tracheal Cytotoxin (TCT) from Bordetella pertussis, which selectively destroys ciliated respiratory cells. This finding explains pertussis pathology and offers a new target for therapies.
Area of Science:
- Microbiology
- Cell Biology
- Pathology
Background:
- Pertussis (whooping cough) is characterized by damage to respiratory ciliated cells.
- Virulent *Bordetella pertussis* replicates this damage in hamster tracheal cultures.
- Known toxins from *B. pertussis* do not cause this specific cytopathology.
Purpose of the Study:
- To identify and purify the component responsible for *B. pertussis*-induced ciliated cell destruction.
- To characterize the biological activity and purification of this toxin.
Main Methods:
- Purification of a glycopeptide from *B. pertussis* culture supernatant.
- Infection of hamster tracheal organ cultures with purified toxin.
- Light and electron microscopy to assess cellular damage.
- Quantitative bioassay measuring inhibition of DNA synthesis in epithelial cells.
Main Results:
- A purified glycopeptide, Tracheal Cytotoxin (TCT), selectively destroys ciliated respiratory epithelial cells.
- TCT causes dose-dependent inhibition of DNA synthesis in hamster tracheal cells.
- A new purification method using column chromatography significantly increases TCT yield.
Conclusions:
- Tracheal Cytotoxin (TCT) is the primary agent responsible for the ciliated cell pathology in pertussis.
- TCT's selective activity provides a target for understanding and potentially treating pertussis.
- Improved purification methods enable larger-scale production of active TCT for further research.