Unveiling the Tactics: How Viruses Evade CRISPR Immunity with RNA-based Anti-CRISPRs

Bacteriophages, a type of virus that infects bacteria, have developed a mechanism to suppress the CRISPR-Cas immune system of bacteria using RNA-based anti-CRISPRs (Racrs). These Racrs mimic the repeat sequences in the CRISPR array and bind to Cas proteins, interfering with the formation of the CRISPR-Cas effector complexes. This immune evasion strategy allows phages and plasmids to infect a wide range of prokaryotic organisms. The discovery of Racrs presents new opportunities to control the activity of CRISPR-Cas technologies.