Periodic vs. intermittent adaptive cycles in quasispecies co-evolution

TL;DR

This paper models the co-evolution of viruses and immune systems, revealing how their interactions lead to different dynamic regimes like periodic or intermittent cycles influenced by mutation rates and population factors.

Contribution

It introduces a novel abstract model showing the interdependence of error thresholds and immune response in virus-immune co-evolution, highlighting dynamic regime transitions.

Findings

Transition between periodic and intermittent cycles depends on mutation rate.

Stochastic fluctuations induce an evolutionary chase in the model.

Simulation results demonstrate the influence of population size and immune response.

Abstract

We study an abstract model for the co-evolution between mutating viruses and the adaptive immune system. In sequence space, these two populations are localized around transiently dominant strains. Delocalization or error thresholds exhibit a novel interdependence because immune response is conditional on the viral attack. An evolutionary chase is induced by stochastic fluctuations and can occur via periodic or intermittent cycles. Using simulations and stochastic analysis, we show how the transition between these two dynamic regimes depends on mutation rate, immune response, and population size.