"Bacteria have developed a formidable arsenal of sophisticated strategies to neutralize viruses, but phages always seem to find a way to evolve, persist and abound. Studies of the complex evolutionary dynamics between phages and bacteria led to the discovery of a widespread bacterial defence system called CRISPR/Cas. On page 489 of this issue, Seed et al. report the remarkable finding that some phages that infect the bacterial pathogen Vibrio cholerae have also acquired a functional CRISPR/Cas system in their own genome which allows them to neutralize an unrelated antivirus system in their bacterial host"
Bacteriophage graphic courtesy of Russell Kightley Media