The phage-host arms race: Elucidating defence and anti-defence strategies

The continuous evolutionary arms race between bacteria and their viral predators—bacteriophages—has driven the emergence of a vast repertoire of molecular defence and counterdefence systems. Among these are CRISPR-Cas systems, the adaptive immune systems of bacteria that record genetic information from past phage encounters to recognise and neutralise future infections. In response, phages have evolved a variety of anti-CRISPR (Acr) proteins that inhibit these host immune pathways, enabling successful infection.

During my PhD research, I contributed to this expanding field by identifying and characterising AcrVIB1, an anti-CRISPR protein that inhibits the RNA-targeting CRISPR-Cas13b system. This discovery not only revealed a new layer of phage counterdefence but also offered insights into mechanisms that could be repurposed for biotechnology and RNA-targeting therapeutics.

Expanding on this work in my postdoctoral research, I now explore the defence capabilities encoded by phages themselves, with a particular focus on jumbo phages—viruses with exceptionally large genomes. Using randomised, targeted, and bioinformatic approaches, I investigate how jumbo phages evade or neutralise bacterial defence mechanisms, revealing previously unknown viral strategies that further illuminate the complexity of the phage-host conflict.