Applying predator-prey theory to modelling immune-mediated, within-host interspecific parasite interactions

Predator-prey models are often applied to the interactions between host immunity and parasite growth A key component of these models is the immune system's functional response, the relationship between immune activity and parasite load Typically, models assume a simple, linear functional response However, based on the mechanistic interactions between parasites and immunity we argue that alternative forms are more likely, resulting in very different predictions, ranging from parasite exclusion to chronic infection By extending this framework to consider multiple infections we show that combinations of parasites eliciting different functional responses greatly affect community stability Indeed, some parasites may stabilize other species that would be unstable if infecting alone Therefore hosts' immune systems may have adapted to tolerate certain parasites, rather than clear them and risk erratic parasite dynamics We urge for mole detailed empirical information relating immune activity to parasite load to enable better predictions of the dynamic consequences of immune-mediated interspecific interactions within parasite communities