Prokaryotic defense systems: Diversity and evolutionary adaptation

Abstract

Bacteriophages and archaeal viruses are the most abundant biological entities on Earth. Through a long-standing co-evolutionary arms race, they have driven the emergence of a diverse repertoire of prokaryotic defense systems. This review summarizes these systems, highlighting their diverse antiviral mechanisms across distinct stages of viral infection, from surface barriers and inducible innate responses to specific adaptive defenses, and the intricate interplay between these defense strategies. By examining host–virus counter defense dynamics, the trade-off between survival benefit and adaptive cost, the co-evolution of RNA and protein components, and the comparison with eukaryotic immune systems, we underscore the intrinsic complexity and evolutionary plasticity of prokaryotic antiviral immunity. A deeper understanding of these processes and mechanisms will not only shed light on the origins and evolution of the immune system but also provide valuable opportunities for the development of biotechnological tools.

Keywords

ancestral immunity / defense systems / diversity / evolutionary adaptation / prokaryotes

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2026 The Author(s). mLife published by John Wiley & Sons Australia, Ltd on behalf of Institute of Microbiology, Chinese Academy of Sciences.