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Rapidity of antigenic modulation of Bordetella pertussis in modified Hornibrook medium
Abstract:
Modulation of Bordetella pertussis was induced by growth in Hornibrook medium with a high content of magnesium sulphate (C-medium); four pathophysiological activities in the cells or in the whole culture were measured at intervals. Modulation, shown by the extensive loss of protective antigen, histamine-sensitising factor, leuko-cytosis-promoting factor, heat-labile toxin and X-mode specific envelope proteins, occurred during the first 10 h of incubation of X-mode cells in C-medium at 35 degrees C and before the onset of the logarithmic phase of growth. The rapidity of these losses was greater than could be explained by a simple growth-dilution effect and did not appear to be due to release of activity into the culture fluid. It seemed, therefore, that there was selective destruction of pathophysiological activities as well as cessation of synthesis. The activities appeared to be lost at different rates. Mouse-protective activity was lost more rapidly than histamine-sensitising and leukocytosis-promoting activities; heat-labile toxicity was lost more slowly or less completely. Modulation was shown to be easily reversed.
Insights
Bordetella pertussis rapidly loses key virulence factors when grown in a specific medium, a process termed modulation. This modulation is reversible and occurs before significant bacterial growth.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Immunology
Background:
- Bordetella pertussis is the causative agent of whooping cough.
- Virulence factors are crucial for bacterial pathogenesis and immune evasion.
- Understanding the regulation of virulence factors is key to developing effective vaccines and treatments.
Purpose of the Study:
- To investigate the phenomenon of modulation in Bordetella pertussis.
- To characterize the changes in pathophysiological activities during modulation.
- To determine the conditions and kinetics of modulation.
Main Methods:
- Culturing Bordetella pertussis in Hornibrook medium with high magnesium sulfate (C-medium).
- Measuring key virulence factors including protective antigen, histamine-sensitizing factor, leukocytosis-promoting factor, heat-labile toxin, and X-mode specific envelope proteins.
- Assessing changes over time during the initial incubation period.
Main Results:
- Modulation, characterized by significant loss of multiple virulence factors, occurred within 10 hours of incubation in C-medium at 35°C, prior to the logarithmic growth phase.
- The loss of activities was faster than expected from growth dilution and not due to release into the medium, suggesting selective destruction and cessation of synthesis.
- Different activities were lost at varying rates; mouse-protective activity decreased most rapidly, while heat-labile toxicity was lost more slowly.
Conclusions:
- Bordetella pertussis undergoes rapid modulation of virulence factors under specific growth conditions.
- Modulation involves selective destruction and inhibited synthesis of pathophysiological activities.
- The observed modulation is easily reversible, offering potential avenues for therapeutic intervention.