Title When be Temperate: On the Fitness Benefits of Lysis vs. Lysogeny
Publication Type Journal Article
Year of Publication 2019
Authors Li G, Cortez MH, Weitz JS
Journal Environmental Microbiology

Bacterial viruses, i.e., ‘bacteriophage’, can infect and lyse their bacterial hosts, releasing new viral progeny. Yet temperate bacteriophage can also initiate lysogeny, i.e., a latent mode of infection, in which the viral genome is integrated into and replicated with the bacterial chromosome. Subsequently, the integrated viral genome, i..e, the ‘prophage’, can induce and restart the lytic pathway. The deferral of lysis has led to a long-standing question: why be temperate? Here, we explore the dependency of viral fitness on infection mode and ecological context. First, we use network loop analysis to show how a cell-centric metric of fitness (the basic reproduction number) decomposes into contributions to viral fitness from all possible infectious transmissions paths that start and end with infected cells. This analysis suggests that lysogeny should be favored at low host abundances and that induction should occur rarely when integration is favored – a finding that applies to a spectrum of mechanistic models of phage-bacteria dynamics spanning both explicit and implicit representations of intracellular infection dynamics. Second, we use invasion analyses to show when phage-bacteria communities with purely lytic and purely lysogenic endemic infections can and cannot be invaded by the other strategy. Our analysis reveals that lytic phage can, counter-intuitively, facilitate the subsequent invasion of latent strategies. Altogether, our results provide a framework for understanding the costs and benefits of being temperate.

URL https://www.biorxiv.org/content/10.1101/709758v1.abstract
DOI 10.1101/709758