RT Journal Article
SR Electronic
T1 Immune Loss as a Driver of Coexistence During Host-Phage Coevolution
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 105908
DO 10.1101/105908
A1 Jake L Weissman
A1 Rayshawn Holmes
A1 Rodolphe Barrangou
A1 Sylvain Moineau
A1 William F Fagan
A1 Bruce Levin
A1 Philip LF Johnson
YR 2017
UL http://biorxiv.org/content/early/2017/02/03/105908.abstract
AB Bacteria and their viral predators face a constant pressure for augmented immune and infective capabilities respectively. Under this reciprocally imposed selective regime we expect to see a runaway arms race dynamic leading to rapid extinction of one species or the other. Despite this prediction, in many systems host and phage coexist with minimal coevolution. Previous work explained this puzzling phenomenon by invoking spatial structure or fitness tradeoffs, which can drive coexistence and the diminishment of an arms race dynamic. Unfortunately, these explanatory mechanisms do not apply to all systems. Here we propose a new hypothesis, that the regular loss of immunity by the bacterial host can also produce robust host-phage coexistence. We pair a general model of immunity with an experimental and theoretical case study of the CRISPR immune system to characterize and contrast the behavior of tradeoff and loss mechanisms in well-mixed systems. We find that, while both a cost of immunity and the loss of immunity can lead to stable coexistence, only a loss mechanism can do so robustly within a realistic region of parameter space.