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Updated: Jul 8, 2026

Using a Bacterial Pathogen to Probe for Cellular and Organismic-level Host Responses
Published on: February 22, 2019
Pathogen interactions, population cycles, and phase shifts
Joanne Lello1, Rachel A Norman, Brian Boag
1School of Biosciences, Cardiff University, Cardiff CF10 3TL, Wales, UK. lelloj@cardiff.ac.uk
Abstract:
Interspecific pathogen interactions can profoundly affect pathogen population dynamics and the efficacy of control strategies. However, many pathogens exhibit cyclic abundance patterns (e.g., seasonality), and temporal asynchrony between interacting pathogens could reduce the impact of those interactions. Here we use an extension of our previously published model to investigate the effects of cycles on pathogen interaction. We demonstrate that host immune memory can maintain the impact of an interaction, even when the effector pathogen abundance is low or the pathogen is absent. Paradoxically, immune memory can result in pathogens interacting more strongly when temporally out of phase. We find that interactions between species can result in changes to the temporal pattern of the affected species. We further demonstrate that this may be observed in a natural host-pathogen system. Given the continuing debate regarding the relevance of pathogen interactions in natural systems and increasing concern about treatment strategies for coinfections, both the discovery of a shift in cycle in empirical data and the mechanism by which we identified it are important. Finally, because the model structure used here is analogous to models of a simple predator-prey system, we also consider the consequences of these findings in the context of that system.
Insights
Host immune memory can sustain pathogen interactions, even when pathogen levels are low. This immune memory can paradoxically strengthen interactions between out-of-phase pathogens, altering disease cycles.
Area of Science:
- Ecology
- Epidemiology
- Immunology
Background:
- Interspecific pathogen interactions significantly influence pathogen dynamics and control strategies.
- Cyclic pathogen abundance patterns (e.g., seasonality) can lead to temporal asynchrony, potentially reducing interaction impacts.
Purpose of the Study:
- To investigate the effects of cyclic abundance patterns on interspecific pathogen interactions using an extended mathematical model.
- To explore the role of host immune memory in modulating these interactions.
Main Methods:
- Extension of a previously published mathematical model to incorporate cyclic pathogen dynamics.
- Analysis of model outputs to identify conditions under which interactions are maintained or altered.
- Consideration of analogous predator-prey system dynamics.
Main Results:
- Host immune memory can maintain the impact of pathogen interactions, irrespective of effector pathogen abundance.
- Immune memory can paradoxically intensify interactions between temporally asynchronous pathogens.
- Interspecific interactions can alter the temporal patterns of the affected pathogen species.
Conclusions:
- Host immune memory is a critical factor in sustaining interspecific pathogen interactions, even under asynchronous conditions.
- The findings have implications for understanding disease dynamics in natural systems and managing coinfections.
- The model provides a framework for investigating ecological interactions analogous to predator-prey systems.
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