Unlike antibiotic resistance, for which most molecular mechanisms are well characterized, only a few prokaryote virus defense mechanisms were known until recently. Over the past several years, dozens more have been discovered including restriction-modification systems (R-M), toxin-antitoxin (TA) systems, CBASS5, BREX, DISARM, CRISPR-Cas, and many more, with new defense systems being discovered at a high rate. The striking diversity in both the mechanisms of action and the taxonomic range as well as the high rate of continued discovery provide clear evidence that an enormous number of defense systems remain unknown.
Like most forms of life, evolution of prokaryotes is driven in large part by the incessant arms race with viruses. With each new defense system uncovered, our window into prokaryote ecology and the selective pressures shaping genome evolution becomes clearer. Most bacteria, and likely most archaea, possess a wide variety of immune systems which may be virus or environment specific. Uncovering the factors that shape the evolution and horizontal exchange of defense genes is central to the pursuit of general theoretical models of host-pathogen coevolution. In a more practical vein, understanding the ecological and host range of defense systems is required to evaluate candidates for phage therapy.
For this Collection, we welcome articles covering all areas under the umbrella of prokaryote virus defense evolution. Topics of interest include but are not limited to:
- Defense system discovery
- Defense system phylogeny
- Horizontal exchange of defense systems
- Mathematical modelling of defense system evolution
- Antidefense systems.