Model of bacterial toxin-dependent pathogenesis explains infective dose

Area of Science:

• Infectious Disease Dynamics
• Microbial Pathogenesis
• Theoretical Biology

Background:

• The infective dose, the minimum pathogen amount to initiate infection, varies significantly across species.
• Existing empirical data suggest a correlation between pathogen mechanism and infective dose, but a theoretical basis is lacking.

Purpose of the Study:

• To investigate the hypothesis that pathogen infective doses are determined by their mechanism of action.
• To provide a theoretical explanation for variations in infective dose based on local versus distant pathogenic mechanisms.

Main Methods:

• Development of simple analytical models to explore the relationship between pathogenesis mechanism and infective dose.
• Utilizing a stochastic, spatially explicit, mechanistic within-host model for bacterial infections dependent on toxin activity.

Main Results:

• The model demonstrates that pathogens employing locally acting toxins have smaller infective doses compared to those using diffusive toxins.
• Pathogens with local mechanisms require lower initial pathogen numbers for infection.
• Pathogens with distant mechanisms exhibit faster spread and potentially greater host damage.

Conclusions:

• The mode of action in pathogenesis significantly influences the infective dose.
• Local pathogenetic mechanisms are associated with smaller infective doses.
• Distantly acting toxins, while requiring larger infective doses, can lead to more rapid disease progression and increased host damage.