A bacteriophage encodes its own CRISPR/Cas adaptive response to evade host innate immunity.

CRISPR/Cas systems are bacterial adaptive immune systems that provide sequence-specific protection from invading nucleic acids, including from bacteriophages; in a notable reverse a vibriophage-encoded CRISPR/Cas system, used to disable a bacteriophage inhibitory chromosomal island in Vibrio cholerae, is identified.