Event

Individual-level heterogeneity often drives ecological and evolutionary dynamics.  The effects of individual variation are especially clear in host-parasite interactions, and all the more so during a global pandemic: hosts exhibit remarkable heterogeneity in the strength, speed and specificity of their immune responses, which in turn generates varied susceptibility to infectious and autoimmune diseases and varied propensity to transmit disease.  Why do hosts vary so much?  One important catergory of explanation for host variation arises from cost-benefit analysis of defense.  I will illustrate how resource costs, immunopathological costs, and multiple-fronts costs of immune defense help to explain the maintenance of host heterogeneity in natural populations.  I will then focus on a particular example of a multiple-fronts cost of defense in mammals: when T-helper cells polarize into worm-clearing and germ-clearing factions.  Subtle differences in initial conditions can be amplified by the collective behavior of T-helper cells to generate radically different system-level responses in different hosts.  Divergent T-helper cell dynamics may therefore explain a good deal of between-host variation in the course of infection. I will also outline how adaptive systems analysis is beginning to shed light on the function of “agile swarms” of these cells during infection, including worm-germ co-infections.

Host: Dustin Brisson

Princeton University

https://algraham.princeton.edu/

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