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Prophage Provide a Safe Haven for Adaptive Exploration in Temperate Viruses
Lindi M Wahl1, Tyler Pattenden2
1Applied Mathematics, Western University, London, Ontario N6A 5B7, Canada lwahl@uwo.ca.
Genetics
|March 20, 2017
Summary
Temperate viruses benefit from mutations arising in the prophage state, which acts as a genetic refuge. This state shields beneficial mutations from genetic drift, aiding viral adaptation and evolution.
Area of Science:
- Virology
- Evolutionary Biology
- Genetics
Background:
- Prophage sequences are a significant part of the temperate virus gene pool.
- These sequences can undergo mutational decay but also serve as a source for adaptive mutations.
- Temperate viruses exhibit a dual life cycle, alternating between virulent (lytic) and temperate phases.
Purpose of the Study:
- To develop a life-history model for temperate viruses encompassing both lytic and temperate phases.
- To analyze the survival of beneficial mutations affecting different life cycle stages and transitions.
- To determine the impact of the prophage state on the evolutionary dynamics of beneficial mutations.
Main Methods:
- Development of a mathematical life-history model for temperate viruses.
- Simulation and analysis of mutation survival under varying fitness effects and life cycle phases.
- Comparison of mutation survival probabilities originating in the prophage versus lytic states.
Main Results:
- Beneficial mutations have a higher probability of long-term survival if they originate in the prophage state.
- This effect persists even for mutations expressed only during the lytic phase, due to reduced offspring variance in the temperate cycle.
- While the prophage state offers a refuge, the lytic phase generates a higher number of total mutations.
Conclusions:
- The prophage state acts as a crucial refuge, protecting beneficial mutations from genetic drift.
- Temperate viruses can explore adaptive evolutionary pathways within the shielded prophage environment.
- The interplay between the prophage refuge and lytic replication shapes the overall adaptive landscape for temperate viruses.
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