Collective decisions among bacterial viruses

Authors

Richard I. Joh, Eberhard O. Voit, Joshua S. Weitz, Georgia Institute of Technonology

Yuriy Mileyko, Duke University

Abstract

For many temperate bacteriophages, the decision of whether to kill hosts (lytic pathway) or enter a latent state (lysogenic pathway) depends on the multiplicity of infection. In this talk, I present a quantitative model of gene regulatory dynamics to describe how phages make collective decisions within host cells. Unlike most previous studies, the copy number of viral genomes (viral genome concentration) is treated as a variable. In the absence of feedback loops, viral mRNA transcription is expected to be proportional to the viral copy number. However, when there are nonlinear feedback loops in viral gene regulation, small changes in viral copy number can lead to dramatic changes in steady state viral gene expression. Our model shows that gene expression patterns are sensitive to changes in viral copy number and there can be a domain of copy number where the system becomes bistable. Hence, the viral copy number is a key control parameter determining host cell fates. This suggests that bacterial viruses can respond adaptively to changes in population dynamics, and can make alternative decisions in uncertain environments as a bet-hedging strategy. Finally, I present a stochastic version of viral gene regulation and discuss speed-accuracy trade-offs in the context of cell fate determination by viruses.

Back to APS March Meeting 2010 Focus Session on Physics of Behavior -- From Molecules to Organisms.