# Experimental Evolution Studies in Φ6 Cystovirus

## TL;DR

This paper reviews decades of research using Φ6 cystovirus to study how viruses evolve in controlled lab settings, offering insights into mutation, adaptation, and potential applications to human viruses.

## Contribution

The paper provides a comprehensive review of experimental evolution studies with Φ6, highlighting its utility as a model for understanding RNA virus evolution.

## Key findings

- Φ6's high mutation rate and lab-friendly traits make it ideal for studying viral evolution.
- Experiments with Φ6 have explored mutation fitness, co-infection effects, host range evolution, and thermostability.
- Φ6's non-pathogenic nature and RNA genome make it a relevant model for human-infecting RNA viruses.

## Abstract

Experimental evolution studies, in which biological populations are evolved in a specific environment over time, can address questions about the nature of spontaneous mutations, responses to selection, and the origins and maintenance of novel traits. Here, we review more than 30 years of experimental evolution studies using the bacteriophage (phage) Φ6 cystovirus. Similar to many lab-studied bacteriophages, Φ6 has a high mutation rate, large population size, fast generation time, and can be genetically engineered or cryogenically frozen, which facilitates its rapid evolution in the laboratory and the subsequent characterization of the effects of its mutations. Moreover, its segmented RNA genome, outer membrane, and capacity for multiple phages to coinfect a single host cell make Φ6 a good non-pathogenic model for investigating the evolution of RNA viruses that infect humans. We describe experiments that used Φ6 to address the fitness effects of spontaneous mutations, the consequences of evolution in the presence of coinfection, the evolution of host ranges, and mechanisms and consequences of the evolution of thermostability. We highlight open areas of inquiry where further experimentation on Φ6 could inform predictions for pathogenic viruses.